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Psoriasis is a prevalent, inflammatory skin disease without cure. Further research is required to unravel dysregulated processes and develop new therapeutic interventions. The lack of suitable in vivo and in vitro preclinical models is an impediment in the psoriasis research. Recently, the development of 3D skin models has progressed including replicas with disease-like features. To investigate the use of in vitro models as preclinical test tools, the study focused on treatment responses of 3D skin replicas. Cytokine-priming of skin organoids induced psoriatic features like inflammation, antimicrobial peptides (AMP), hyperproliferation and impaired differentiation. Topical application of dexamethasone (DEX) or celastrol (CEL), a natural anti-inflammatory compound reduced the secretion of pro-inflammatory cytokines. DEX and CEL decreased the gene expression of inflammatory mediators. DEX barely affected the psoriatic AMP transcription but CEL downregulated psoriasis-driven AMP genes. Subcutaneous application of adalimumab (ADM) or bimekizumab (BMM) showed anti-psoriatic effects via protein induction of the differentiation marker keratin-10. Dual blockage of TNF-α and IL-17A repressed the inflammatory psoriasis phenotype. BMM inhibited the psoriatic expression of AMP genes and induced KRT10 and cell-cell contact genes. The present in vitro model provides a 3D environment with in vivo-like cutaneous responses and represents a promising tool for preclinical investigations., Competing Interests: Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: The liver-expressed antimicrobial peptide 2 (LEAP2) is a recently recognized anorectic and glucose-regulating hormone with an unknown role in lactation., Objectives: The objectives of this study were as follows: 1) to assess LEAP2 presence in human milk and putative associations with infant body weight and adiposity in the first year of life, 2) to evaluate the impact of maternal weight status on LEAP2 concentration, and 3) to explore the relationship between infant plasma LEAP2 concentration and body weight and adiposity., Methods: This prospective cohort observational study assessed LEAP2 concentration in plasma and milk from lactating women with normal weight (n = 26) or overweight or obesity (OW/OB, n = 26) at 6 mo postpartum and in 6-mo-old infant plasma, examining associations with metabolic and anthropometric variables at 6 mo and 1 y. Maternal plasma and milk leptin and insulin concentrations were also measured. LEAP2 expression in milk fat globules and single-cell-RNA-sequencing datasets was evaluated., Results: LEAP2 was detected in all milk samples assessed (2.08 ± 0.65 ng/mL) and was positively associated with infant triceps (P = 0.022, Cohen f 2 = 1.25) and subscapular (P = 0.008, f 2 = 0.68) skinfolds at 1 y old. Maternal LEAP2 was positively associated with insulin (P = 0.005, f 2 = 0.30) and prepregnancy body mass index (BMI) (P = 0.040, f 2 = 0.17) and negatively associated with gestational weight gain (P = 0.008, f 2 = 0.25) and postpartum weight retention (P = 0.036, f 2 = 0.15). Maternal LEAP2 was higher in plasma (P = 0.039), but not milk of lactating women with OW/OB. Infant plasma LEAP2 (1.98 ± 0.28 ng/mL) was positively associated with weight (P = 0.004, f 2 = 0.63), BMI (P = 0.049, f 2 = 0.37), and weight-for-length (P = 0.024, f 2 = 0.35) z-scores at 1 y old, predominantly in males. No evidence for LEAP2 mRNA expression was found in mammary cells., Conclusions: Milk LEAP2 is a bioactive component that plays a role in infant fat accretion in the first year of life. Although maternal LEAP2 responds to weight change in pregnancy and lactation, infant plasma LEAP2 might be involved in body weight regulation in early life. This trial was registered at clinicaltrials.gov as NCT05798676., Competing Interests: Conflict of interest The authors report no conflicts of interest., (Copyright © 2024 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

In humans and mice, the induction of interleukin (IL)-17 expression enhances epithelial barrier integrity through the secretion of antimicrobial peptides (AMP), thereby improving antibacterial defense. However, it is unclear whether IL-17 has similar antibacterial effects in chickens by modulating the expression of AMPs, such as avian beta-defensins (also known as gallinacins) and cathelicidins. This study evaluated the in vivo effects of inoculating 20-day-old broiler chickens with two doses of a plasmid encoding chicken IL-17 (pCDNA3.1/rchIL-17-V5-HIS TOPO plasmid [pCDNA3.1-IL-17]; 5 or 10 μg/bird). On day 23 of age, all broilers, except those in the negative control group, were orally challenged with a virulent Clostridium perfringens strain for three days. To investigate IL-17-mediated effects against C. perfringens infection, the expression of avian beta-defensin 1 (avBD1), avBD2, avBD4, avBD6, cathelicidins, and inducible nitric oxide synthase (iNOS) genes were quantified, and gross necrotic enteritis (NE) lesion scores were assessed in the small intestine. The results showed that broilers receiving the higher dose of pCDNA3.1-IL-17 (10 μg) had significantly lower NE lesion scores compared to those receiving the lower dose (5 μg), the vector control, and the positive control groups. Furthermore, the expression of all avian beta-defensins and cathelicidin genes was detectable across all groups, regardless of treatment and time points. IL-17 treatment led to significantly higher expression of avBD1, avBD2, avBD4, avBD6, cathelicidin, and iNOS in the duodenum, jejunum, and ileum compared to control chickens. In C. perfringens-infected chickens, the expression of avBD1, avBD2, avBD4, cathelicidin, and iNOS in the ileum was significantly higher than in control chickens. Pre-treatment with the higher dose of pCDNA3.1-IL-17 (10 μg) in infected chickens was associated with reduced NE lesion severity and increased expression of avBD1, avBD2, cathelicidin, and iNOS in the ileum, but not avBD4 and avBD6. These findings provide new insights into the potential effect of IL-17 and reduction in NE lesion severity by modulating AMP expression which may be involved in mediating protective immunity against intestinal infection with C. perfringens., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: In a gene expression analysis comparing sinus mucosa samples from allergic fungal rhinosinusitis (AFRS) patients with samples from non-AFRS chronic rhinosinusitis with nasal polyp (CRSwNP) patients, the antimicrobial peptide (AMP) histatin 1 (HTN1) was found to be the most differentially downregulated gene in AFRS., Objective: We sought to identify the molecular etiology of the downregulated expression of HTN1., Methods: We used RT-PCR to compare the expression of AMPs and a fungistasis assay to evaluate the antifungal activity of sinus secretions. Using flow cytometry, we characterized the presence of T H 17/T H 22 cells and signal transducer and activator of transcription (STAT) signaling from AFRS patients, non-AFRS CRSwNP patients, and healthy controls., Results: We confirmed decreased expression of AMPs in AFRS sinus mucosa with concordant decrease in antifungal activity in sinus secretions. IL-22 and IL-22-producing T cells were deficient within sinus mucosa of AFRS patients. In vitro studies demonstrated a defect in IL-6/STAT3 signaling critical for T H 17/T H 22 differentiation. Epithelial cells from AFRS patients could express AMPs when stimulated with exogenous IL-22/IL-17 and circulating T H 17 cell abundance was normal., Conclusions: Similar to other hyper-IgE syndromes, but distinct from CRSwNP, AFRS patients express a defect in STAT3 activation limited to IL-6-dependent STAT3 phosphorylation that is critical for T H 17/T H 22 differentiation. This defect leads to a local deficiency of IL-17/IL-22 cytokines and deficient AMP expression within diseased sinus mucosa of AFRS patients. Our findings support evaluation of therapeutic approaches that enhance airway AMP production in AFRS., Competing Interests: Disclosure statement This work was supported by National Institutes of Health grants R01HL117181 (D.B.C.), HL140398 (D.B.C.), R01AI135803 (D.B.C.), and R01AI135803 (D.B.C.) and Department of Veterans AffairsBiomedical Laboratory Research and Development Merit Review Award I01BX004828 (D.B.C.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health or the Veterans Administration Office of Research and Development. This project was further supported by the Cytometry and Cell Sorting Core at Baylor College of Medicine with funding from the CPRIT Core Facility Support Award (CPRIT-RP180672), and the National Institutes of Health (CA125123 and RR024574). Disclosure of potential conflict of interest: A. U. Luong owns stock in Aerin Medical (Mountain View, Calif) and serves as a consultant for GlaxoSmithKline (Brentford, United Kingdom), Lyra Therapeutics (Watertown, Mass), Maxwell Biosciences (Austin, Texas), Medtronic (Dublin, Ireland), NeuroENT (Galway, Ireland), Sanofi (Paris, France), SoundHealth (San Francisco, Calif), and Stryker (Kalamazoo, Mich). D. B. Corry owns stock options in Maxwell Biosciences (Austin, Texas). M. J. Citardi serves as a consultant for 3D Matrix (Newton, Mass), Acclarent (Irvine, Calif), LynxMD (Palo Alto, Calif), MicroGenDx (Lubbock, Texas), and NeuroENT (Galway, Ireland). W. C. Yao is a consultant for Acclarent (Irvine, Calif), Aerin Medical (Mountain View, Calif), and Medtronic (Minneapolis, Minn) and is on the Speaker’s Bureau for Optinose Inc (Yardley, Pa)., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Neutrophil cationic proteins (NCPs) are a group of granule antimicrobial and inflammatory proteins released by activated neutrophils. These proteins primarily function via their positively charged structure, which facilitates interactions with bacterial membranes and the formation of immunogenic DNA complexes, thereby contributing to the initiation of wound repair in injured skin. After analyzing the structural properties of secreted neutrophil granule proteins, we identified OLFM4 as the only negatively charged molecule that interferes with NCP oligomerization. Through this interference, OLFM4 can inhibit neutrophil-mediated bacterial killing and DNA complex-dependent activation of Toll-like receptor 9 (TLR9) in plasmacytoid dendritic cells (pDCs) and neutrophils. While addition of exogenous OLFM4 blocks these processes, OLFM4 inhibition enhances neutrophil-dependent bacterial killing and DNA complex formation, ultimately leading to accelerated closure of skin wounds., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Liver-expressed antimicrobial peptide 2 (LEAP2) is a peptide that counteracts the hunger hormone ghrelin-induced functions. Recently, we showed that vertical sleeve gastrectomy (VSG) did not alter the serum LEAP2 concentration in individuals with obesity. Here, we investigated the effects of VSG in both chow diet (CD)-fed and high-fat diet (HFD)-fed mice. In CD-fed mice, VSG increased plasma LEAP2 levels and hepatic Leap2 mRNA levels while decreasing body weight, blood glucose levels, and ghrelin levels. Intraperitoneal (ip) administration of ghrelin reversed these changes. These effects were found in both male and female mice. In contrast, VSG or weight loss in HFD-induced obese mice decreased LEAP2 levels. After fasting, the plasma LEAP2 concentration was in the following order: hepatic vein > abdominal aorta > portal vein. A high glucose concentration robustly increased the plasma LEAP2 concentration in the hepatic vein and abdominal aorta but not in the portal vein. In addition, corn oil or palmitate increased LEAP2 expression and secretion. The increase in LEAP2 levels after the meal tolerance test was delayed in the human subjects with diabetes. Our data suggest that various factors (metabolic, hormonal, and nutritional) regulate LEAP2, and the liver is the predominant site for the production and secretion of LEAP2. Furthermore, the interaction between ghrelin and LEAP2 is involved in the pathogenesis of obesity and diabetes., (© 2024. The Author(s).)

The antimicrobial resistance crisis along with challenges of antimicrobial discovery revealed the vital necessity to develop new antibiotics. Many of the animal proline-rich antimicrobial peptides (PrAMPs) inhibit the process of bacterial translation. Genome projects allowed to identify immune-related genes encoding animal host defense peptides. Here, using genome mining approach, we discovered a family of proline-rich cathelicidins, named rumicidins. The genes encoding these peptides are widespread among ruminant mammals. Biochemical studies indicated that rumicidins effectively inhibited the elongation stage of bacterial translation. The cryo-EM structure of the Escherichia coli 70S ribosome in complex with one of the representatives of the family revealed that the binding site of rumicidins span the ribosomal A-site cleft and the nascent peptide exit tunnel interacting with its constriction point by the conservative Trp23-Phe24 dyad. Bacterial resistance to rumicidins is mediated by knockout of the SbmA transporter or modification of the MacAB-TolC efflux pump. A wide spectrum of antibacterial activity, a high efficacy in the animal infection model, and lack of adverse effects towards human cells in vitro make rumicidins promising molecular scaffolds for development of ribosome-targeting antibiotics., (© 2024. The Author(s).)

S almonella enterica is comprised of over 2,500 serovars, in which non-typhoidal serovars (NTS), Enteritidis (SE), and Typhimurium (STM) are the most clinically associated with human infections. Although NTS have similar genetic elements to cause disease, phenotypic variation including differences in lipopolysaccharide (LPS) composition may control immune evasion. Here, we demonstrate that macrophage host defenses and LL-37 antimicrobial efficacy against SE and STM are substantially altered by LPS heterogeneity. We found that SE evades macrophage killing by inhibiting phagocytosis while STM survives better intracellularly post-phagocytosis. SE-infected macrophages failed to activate the inflammasomes and subsequently produced less interleukin-1β (IL-1β), IL-18, and interferon λ. Inactivation of LPS biosynthesis genes altered LPS composition, and the SE LPS-altered mutants could no longer inhibit phagocytosis, inflammasome activation, and type II interferon signaling. In addition, SE and STM showed differential susceptibility to the antimicrobials LL-37 and colistin, and alteration of LPS structure substantially increased susceptibility to these molecules. Collectively, our findings highlight that modification of LPS composition by Salmonella increases resistance to host defenses and antibiotics., Competing Interests: The authors declare no conflict of interest.

Research on antimicrobial peptides (AMPs) has been conducted as a solution to overcome antibiotic resistance. In particular, the synergistic effect that appears when two or more AMPs are used in combination has been observed. To find an effective synergistic combination, it is necessary to understand the underlying mechanism. However, a consistent explanation for this phenomenon has not yet been provided due to limitations in experimentally determining or predicting the structure of the heteroaggregates formed by the interactions between different AMPs and the interaction of the aggregate surface with the lipid membrane surface. In this study, we conducted molecular dynamics simulations for two heterogeneous aggregates of melittin-indolicidin and pexiganan-indolicidin to observe their structures in the solution phase and their interactions with the lipid membrane. We aimed to determine how the surfaces of these aggregates interact with the lipid membrane. Due to the different amino acid residue sequence characteristics of melittin and pexiganan, we found that when the two AMPs bind to indolicidin, they form aggregates with completely different structural characteristics. Accordingly, the sequence characteristics of pexiganan, which exhibits a relatively unstable structure compared to melittin in aqueous solution or on lipid membranes, allow for a more stable interaction with the lipid membrane when forming aggregates with indolicidin, effectively inhibiting the integrity of the lipid membranes. We also found that the amino acid residues forming the surface of the AMP aggregate show differential binding strengths to different lipid species forming the lipid membrane, thereby disrupting the membrane in a way that weakens its integrity. Through this, we provided insight into the basic principle of how the synergistic effect of AMPs occurs.

Pneumococcal surface protein A (PspA) is an important virulence factor in Streptococcus pneumoniae that binds to lactoferrin and protects the bacterium from the bactericidal action of lactoferricins-cationic peptides released upon lactoferrin proteolysis. The present study investigated if PspA can prevent killing by another cationic peptide, indolicidin. PspA-negative pneumococci were more sensitive to indolicidin-induced killing than bacteria expressing PspA, suggesting that PspA prevents the bactericidal action of indolicidin. Similarly, chemical removal of choline-binding proteins increased sensitivity to indolicidin. The absence of capsule and PspA had an additive effect on pneumococcal killing by the AMP. Furthermore, anti-PspA antibodies enhanced the bactericidal effect of indolicidin on pneumococci, while addition of soluble PspA fragments competitively inhibited indolicidin action. Previous in silico analysis suggests a possible interaction between PspA and indolicidin. Thus, we hypothesize that PspA acts by sequestering indolicidin and preventing it from reaching the bacterial membrane. A specific interaction between PspA and indolicidin was demonstrated by mass spectrometry, confirming that PspA can actively bind to the AMP. These results reinforce the vaccine potential of PspA and suggest a possible mechanism of innate immune evasion employed by pneumococci, which involves binding to cationic peptides and hindering their ability to damage the bacterial membranes., (© 2024. The Author(s).)

The collaboration between the microbiota, mucosa, and intestinal epithelium is crucial for defending against pathogens and external antigens. Dysbiosis disrupts this balance, allowing pathogens to thrive and potentially enter the bloodstream, triggering immune dysregulation and potentially leading to sepsis. Antimicrobial peptides like LL-37 and CRAMP are pivotal in innate immune defense. Their expression varies with infection severity, exhibiting a dual pro- and anti-inflammatory response. Understanding this dynamic is key to comprehending sepsis progression. In our study, we examined the inflammatory response in CRAMP knockout mice post-cecal ligation and puncture (CLP). We assessed its impact on brain tissue damage and the intestinal microbiota. Our findings revealed higher gene expression of S100A8 and S100A9 in the prefrontal cortex of wild-type mice versus CRAMP-knockout mice. This trend was consistent in the hippocampus and cerebellum, although protein concentrations remained constant. Notably, there was a notable increase in Escherichia coli, Lactobacillus spp., and Enterococcus faecalis populations in wild-type mice 24 h post-CLP compared to the CRAMP-deficient group. These results align with our previous data suggesting that the absence of CRAMP may confer protection in this sepsis model., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Representing severe morbidity and mortality globally, respiratory infections associated with chronic respiratory diseases, including complicated pneumonia, asthma, interstitial lung disease, and chronic obstructive pulmonary disease, are a major public health concern. Lung health and the prevention of pulmonary disease rely on the mechanisms of airway surface fluid secretion, mucociliary clearance, and adequate immune response to eradicate inhaled pathogens and particulate matter from the environment. The antimicrobial proteins and peptides contribute to maintaining an antimicrobial milieu in human lungs to eliminate pathogens and prevent them from causing pulmonary diseases. The predominant antimicrobial molecules of the lung environment include human α- and β-defensins and cathelicidins, among numerous other host defense molecules with antimicrobial and antibiofilm activity such as PLUNC (palate, lung, and nasal epithelium clone) family proteins, elafin, collectins, lactoferrin, lysozymes, mucins, secretory leukocyte proteinase inhibitor, surfactant proteins SP-A and SP-D, and RNases. It has been demonstrated that changes in antimicrobial molecule expression levels are associated with regulating inflammation, potentiating exacerbations, pathological changes, and modifications in chronic lung disease severity. Antimicrobial molecules also display roles in both anticancer and tumorigenic effects. Lung antimicrobial proteins and peptides are promising alternative therapeutics for treating and preventing multidrug-resistant bacterial infections and anticancer therapies.

Antimicrobial peptides (AMPs) are crucial in the humoral immunity aspect of invertebrates' innate immune systems. However, studies on AMP discovery in the Pacific white shrimp (Litopenaeus vannamei) using omics data have been limited. Addressing the growing concern of antibiotic resistance in aquaculture, this study focused on the identification and characterization of AMPs in L. vannamei using advanced genomic and transcriptomic techniques. The genome of L. vannamei was performed to predict and identify a total of 754 AMP-derived genes, distributed across most chromosomes and spanning 24 distinct AMP families, and further identified 236 AMP-derived genes at the mRNA level in hemocytes. A subset of 20 chemically synthesized peptides, derived from these genes, exhibited significant antimicrobial activity, with over 85% showing effectiveness against key bacterial strains such as Staphylococcus aureus and Vibrio parahaemolyticus. The expression patterns of these AMPs were also investigated in different shrimp tissues and at various infection stages, revealing dynamic responses to pathogenic challenges. These findings highlight the significant potential of AMPs in L. vannamei as novel, effective alternatives to traditional antibiotics in aquaculture, offering insights into their diverse structural properties and biological functions. Together, this comprehensive characterization of the AMP repertoire in L. vannamei demonstrates the efficacy of using omics data for AMP discovery and lays the groundwork for their potential applications., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The transplantation of periodontal ligament stem cells (PDLSCs) has been shown to enhance periodontal regeneration in animal models and clinical trials. However, it is not known whether PDLSCs are antibacterial and whether this affects oral microbiota and periodontal regeneration., Methods: We isolated human PDLSCs from periodontal ligament of extracted teeth. Rats' periodontal fenestration defects were prepared, and treated with PDLSC injections (Cell group), using saline injections (Saline group) as the control. The oral microbiota was explored by 16 S rDNA sequencing and compared with that before surgery (PRE group). The antibacterial property of PDLSCs and its underlying mechanism were tested in vitro., Results: Microbiome analyses reveal a decreased biodiversity, a changed community structure, and downregulated community functions of the oral microbiome in the Saline group. PDLSCs injections enhance periodontal regeneration, reverse the decrease in diversity, and increase the abundance of non-pathogenic bacterial Bifidobacterium sp. and Lactobacillus sp., making the oral microbiome similar to that of the PRE group. In vitro, PDLSCs inhibit the growth of Staphylococcus aureus, Escherichia coli, and Fusobacterium nucleatum. The main mechanism of action is postulated to involve production of the cationic antimicrobial peptide LL-37., Conclusions: Our findings reveal that PDLSC injections enhance periodontal regeneration and regulate the oral microbiome to foster an oral cavity microenvironment conducive to symbiotic microbiota associated with health., (© 2024. The Author(s).)

Rosacea is a chronic inflammatory skin disease that typically affects the central facial area. Its main clinical symptoms include paroxysmal flushing, telangiectasia, and non-temporary erythema. Cell-free adipose tissue extracts (ATEs) are liquid components extracted from human adipose tissue that contain large amounts of growth factors. Despite the scar-reducing, anti-aging, and wound-healing effects of ATEs, the efficacy of ATEs in rosacea remains unknown. Therefore, the anti-rosacea effects of ATEs were investigated in human cathelicidin peptide (LL-37) induced rosacea mice and capsaicin (CAP)-stimulated HaCaT keratinocytes. In vitro, ATEs significantly reduced TRPV1 expression, intracellular calcium ions influx and the release of inflammatory factors (such as KLK5, IL-6, IL-8 and TNF-α) after intervening in CAP-stimulated cells. The in vivo results revealed that ATEs alleviated rosacea symptoms, such as erythema score, erythema area, transepidermal water loss, abnormal epidermal thickness, mast cell infiltration and telangiectasia upon downregulating TRPV1 and CD31 expression. Moreover, the up-regulated TRPV1 protein expression was also recovered by ATEs administration in vivo and in vitro. Meanwhile, ATEs demonstrated good biocompatibility. In summary, ATEs could be a potential therapeutic agent for rosacea by regulating inflammation and alleviating telangiectasia., (© 2024. The Author(s).)

Background: Oxidative stress, a condition characterized by excessive production of reactive oxygen species (ROS), can cause significant damage to cellular macromolecules, leading to neurodegeneration. This underscores the need for effective antioxidant therapies that can mitigate oxidative stress and its associated neurodegenerative effects. KC14 peptide derived from liver-expressed antimicrobial peptide-2 A (LEAP 2 A) from Cyprinus carpio L. has been identified as a potential therapeutic agent. This study focuses on the antioxidant and neuroprotective properties of the KC14 peptide is to evaluate its effectiveness against oxidative stress and neurodegeneration., Methods: The antioxidant capabilities of KC14 were initially assessed through in silico docking studies, which predicted its potential to interact with oxidative stress-related targets. Subsequently, the peptide was tested at concentrations ranging from 5 to 45 µM in both in vitro and in vivo experiments. In vivo studies involved treating H 2 O 2 -induced zebrafish larvae with KC14 peptide to analyze its effects on oxidative stress and neuroprotection., Results: KC14 peptide showed a protective effect against the developmental malformations caused by H 2 O 2 stress, restored antioxidant enzyme activity, reduced neuronal damage, and lowered lipid peroxidation and nitric oxide levels in H 2 O 2 -induced larvae. It enhanced acetylcholinesterase activity and significantly reduced intracellular ROS levels (p < 0.05) dose-dependently. Gene expression studies showed up-regulation of antioxidant genes with KC14 treatment under H 2 O 2 stress., Conclusions: This study highlights the potent antioxidant activity of KC14 and its ability to confer neuroprotection against oxidative stress can provide a novel therapeutic agent for combating neurodegenerative diseases induced by oxidative stress., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Despite ongoing research on antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs), their precise translocation mechanism remains elusive. This includes Buforin 2 (BF2), a well-known AMP, for which spontaneous translocation across the membrane has been proposed but a high barrier has been calculated. Here, we used computer simulations to investigate the effect of a nonequilibrium situation where the peptides are adsorbed on one side of the lipid bilayer, mimicking experimental conditions. We demonstrated that the asymmetric membrane adsorption of BF2 enhances its translocation across the lipid bilayer by lowering the energy barrier by tens of kJ mol -1 . We showed that asymmetric membrane adsorption also reduced the free energy barrier of lipid flip-flop but remained unlikely even at BF2 surface saturation. These results provide insight into the driving forces behind membrane translocation of cell-penetrating peptides in nonequilibrium conditions, mimicking experiments.

Aims/hypothesis: Defensins play a crucial role in the innate immune system's first defense against microbial threats. However, little is known about the defensin system in the pancreas, especially in relation to Type 1 diabetes. We explore the expression of defensins in different disease stages of Type 1 diabetes and correlated obtained findings to the degree of inflammation, providing new insights into the disease and the innate immune system., Material and Methods: Pancreases from non-diabetic human organ donors of different age groups and donors with Type 1 diabetes with different disease duration were examined. Sections from head, body and tail of the pancreas were stained for eight different defensins and for immune cells; CD3+, CD45+, CD68+ and NES+ (granulocytes)., Results: In non-diabetic adult controls the level of expression for defensins Beta-1,Alpha-1, Cathelicidin and REG3A correlated with the level of inflammation. In contrast, individuals with Type  1 diabetes exhibit a reduction or absence of several central defensins regardless of the level of inflammation in their pancreas. The expression of Cathelicidin is present in neutrophils and macrophages but not in T-cells in subjects with Type 1 diabetes., Conclusions: Obtained findings suggest a pancreatic dysfunction in the innate immune system and the bridging to the adaptive system in Type 1 diabetes. Further studies on the role of the local innate immune system in Type 1 diabetes is needed., (© 2024. The Author(s).)

Investigating the principles of fish fat deposition and conducting related research are current focal points in fish nutrition. This study explores the endocrine regulation of LEAP2 and GHSR1a in zebrafish by constructing mutantmodels andexamining the effects of the endocrine factors LEAP2 and its receptor GHSR1a on zebrafish growth, feeding, and liver fat deposition. Compared to the wild type (WT), the mutation of LEAP2 results in increased feeding and decreased swimming in zebrafish. The impact is more pronounced in adult female zebrafish, characterized by increased weight, length, width, and accumulation of lipid droplets in the liver.Incontrast, deficiency in GHSR1a significantly reduces the growth of male zebrafish and markedly decreases liver fat deposition.These research findings indicate the crucial roles of LEAP2 and GHSR1a in zebrafish feeding, growth, and intracellular fat metabolism. This study, for the first time, investigated the endocrine metabolic regulation functions of LEAP2 and GHSR1a in the model organism zebrafish, providing initial insights into their effects and potential mechanisms on zebrafish fat metabolism., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Rosacea is a chronic inflammatory skin disorder characterized by immune response-dependent erythema and pustules. S100A9, a proinflammatory alarmin, has been associated with various inflammation-related diseases. However, the specific role of S100A9 in rosacea remains unexplored. Therefore, our objective was to unravel the role of S100A9 in the pathogenesis of rosacea and its underlying molecular mechanisms. In this study, we show that expression levels of S100A9 were elevated in both the lesions and serum of patients with papulopustular rosacea as well as in lesions of the LL37-induced rosacea-like mouse model. Moreover, the upregulation of S100A9 was correlated with clinical severity and levels of inflammatory cytokines. In addition, we demonstrated that S100A9 promoted the production of proinflammatory factors in HaCaT cells by activating toll-like receptor 4/MyD88/NF-κB signaling pathways. Notably, inhibition of S100A9 suppressed the progression of rosacea-like dermatitis and inflammatory responses in the LL37-induced rosacea-like mouse model through toll-like receptor 4/MyD88/NF-κB signaling pathways. In conclusion, this study illustrated that S100A9 participates in the pathogenesis of rosacea by upregulating toll-like receptor 4/MyD88/NF-κB signaling pathways, thereby promoting rosacea-associated skin inflammation. These results not only expand our understanding of the potential role of S100A9 in the development of rosacea but also offer greater insight toward targeted therapies., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Host antimicrobial peptides (AMPs) and extracellular vesicles (EVs) are known to play important roles as part of the immune system, from antimicrobial actions to immune regulation. Recent results also demonstrate that EVs could serve as carriers for AMPs. Related, it was shown that some AMPs can remove the protein corona (PC), the externally adsorbed layer of proteins, from EVs which can be exploited for subtractive proteomics strategies. The interaction of these compounds is thus interesting for multiple reasons from better insight to natural processes to direct applications in EV-based bioengineering. However, we have only limited information on the various ways these species may interact with each other. To reach a broader overview, here we selected twenty-six AMPs, including cell-penetrating peptides (CPPs), and investigated their interactions with red blood cell-derived vesicles (REVs). For this, we employed a complex lipid biophysics including linearly polarized light spectroscopy, flow cytometry, nanoparticle tracking analysis, electron microscopy and also zeta-potential measurements. This enabled the categorization of these peptides into distinct groups. At specific low concentrations, peptides such as LL-37 and lasioglossin-III were effective in PC elimination with minimal disruption of the membrane. In contrast, AMPs like KLA, bradykinin, histatin-5, and most of the tested CPPs (e.g. octa-arginine, penetratin, and buforin II), demonstrate cell-penetrating mechanisms as they could sustain large peptide concentrations with minimal membrane damage. The systematic overview presented here shows the potential mechanism of how AMPs and EVs could interact in vivo, and also how certain peptides may be employed to manipulate EVs for specific applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Bombyx mori cecropin A (Bmcecropin A) has antibacterial, antiviral, anti-filamentous fungal and tumour cell inhibition activities and is considered a potential succedaneum for antibiotics. We clarified the antibacterial mechanism and structure-activity relationships and then directed the structure-activity optimization of Bmcecropin A. Firstly, we found Bmcecropin A shows a strong binding force and permeability to cell membranes like a detergent; Bmcecropin A could competitively bind to the cell membrane with the cell membrane-specific dye DiI, then damaged the membrane for the access of DiI into the cytoplasm and leading to the leakage of electrolyte and proteins. Secondly, we found Bmcopropin A could also bind to and degrade DNA; furthermore, DNA library polymerase chain reaction (PCR) results indicated that Bmcecropin A inhibited DNA replication by non-specific binding. In addition, we have identified C-terminus amidation and serine-lysine- glycine (SLG) amino acids of Bmcecropin A played critical roles in the membrane damage and DNA degradation. Based on the above results, we designed a mutant of Bmcecropin A (E 9 to H, D 17 to K, K 33 to A), which showed higher antibacterial activity, thermostability and pH stability than ampicillin but no haemolytic activity. Finally, we speculated that Bmcecropin A damaged the cell membrane through a carpet model and drew the schematic diagram of its antibacterial mechanism, based on the antibacterial mechanism and the three-dimensional configuration. These findings yield insights into the mechanism of antimicrobial peptide-pathogen interaction and beneficial for the development of new antibiotics., (© 2024 Royal Entomological Society.)

Non-direct antimicrobial cationic peptides (NDACPs) are components of the animal innate immune system. But their functions and association with antimicrobial peptides (AMPs) are incompletely understood. Here, we reveal a synergistic interaction between the AMP AW1 and the NDACP AW2, which are co-expressed in the frog Amolops wuyiensis. AW2 enhances the antibacterial activity of AW1 both in vitro and in vivo, while mitigating the development of bacterial resistance and eradicating biofilms. AW1 and AW2 synergistically damage bacterial membranes, facilitating cellular uptake and interaction of AW2 with the intracellular target bacterial genomic DNA. Simultaneously, they trigger the generation of ROS in bacteria, contributing to cell death upon reaching a threshold level. Moreover, we demonstrate that this synergistic antibacterial effect between AMPs and NDACPs is prevalent across diverse animal species. These findings unveil a robust and previously unknown correlation between AMPs and NDACPs as a widespread antibacterial immune defense strategy in animals., (© 2024. The Author(s).)

Neonatal sepsis is a major global health challenge, leading to significant morbidity and mortality in newborns. The search for precise biomarkers for its early prediction in clinical settings has been ongoing, with heparin-binding protein (HBP) emerging as a promising candidate. Originating from granules in neutrophils, HBP is released into the bloodstream in response to infection and plays a pivotal role in the body's inflammatory response. Its significance extends beyond its inflammatory origins; research indicates dynamic changes in HBP levels are strongly linked to reduce in-hospital mortality, offering a prognostic advantage over existing biomarkers. Furthermore, HBP has demonstrated considerable clinical utility in the early diagnosis and stratification of neonatal sepsis, suggesting its potential as a reliable blood marker for early prediction of the disease and its severity. Its application may extend to guiding the judicious use of antibiotics in treating newborns, addressing a critical aspect of neonatal care. Despite these encouraging results, the precise clinical utility of HBP for diagnosing and treating sepsis in neonates still demands further clarification through extensive research. This review delves into the current scientific understanding of HBP's contribution to diagnosing, prognosticating, and treating neonatal sepsis, while considering its future clinical applications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chen, Li, Li, Liu, Chen, Chen, Yuan and Tao.)

Ghrelin has effects that range from the maturation of the central nervous system to the regulation of energy balance. The production of ghrelin increases significantly during the first weeks of life. Studies have addressed the metabolic effects of liver-expressed antimicrobial peptide 2 (LEAP2) in inhibiting the effects evoked by ghrelin, mainly in glucose homeostasis, insulin resistance, and lipid metabolism. Despite the known roles of ghrelin in the postnatal development, little is known about the long-term metabolic influences of modulation with the endogenous expressed growth hormone secretagogue receptor (GHSR) inverse agonist LEAP2. This study aimed to evaluate the contribution of GHSR signalling during perinatal phases, to neurodevelopment and energy metabolism in young animals, under inverse antagonism by LEAP2[1-14]. For this, two experimental models were used: (i) LEAP2[1-14] injections in female rats during the pregnancy. (ii) Postnatal modulation of GHSR with LEAP2[1-14] or MK677. Perinatal GHSR modulation by LEAP2[1-14] impacts glucose homeostasis in a sex and phase-dependent manner, despite no effects on body weight gain or food intake. Interestingly, liver PEPCK expression was remarkably impacted by LEAP2 injections. The observed results suggests that perinatal LEAP2 exposure can modulate liver metabolism and systemic glucose homeostasis. In addition, these results, although not expressive, may just be the beginning of the metabolic imbalance that will occur in adulthood.

Lipopolysaccharide (LPS) triggers an inflammatory response, causing impairment of cardiomyocyte Ca 2+ and Na  +  regulation. This study aimed to determine whether piscidin-1 (PCD-1), an antimicrobial peptide, improves intracellular Ca 2+ and Na  +  regulation in LPS-challenged atrial cardiomyocytes. Rabbit atrial cardiomyocytes were enzymatically isolated from the left atria. Patch-clamp ionic current recording, intracellular Ca 2+ monitoring using Fluo-3, and detection of cytosolic reactive oxygen species production were conducted in control, LPS-challenged, and LPS + PCD-1-treated atrial cardiomyocytes. LPS-challenged cardiomyocytes showed shortened durations of action potential at their 50% and 90% repolarizations, which was reversed by PCD-1 treatment. LPS-challenged cardiomyocytes showed decreased L-type Ca 2+ channel currents and larger Na + /Ca 2+ exchange currents compared to controls. While LPS did not affect the sodium current, an enhanced late sodium current with increased cytosolic Na + levels was observed in LPS-challenged cardiomyocytes. These LPS-induced alterations in the ionic current were ameliorated by PCD-1 treatment. LPS-challenged cardiomyocytes displayed lowered Ca 2+ transient amplitudes and decreased Ca 2+ stores and greater Ca 2+ leakage in the sarcoplasmic reticulum compared to the control. Exposure to PCD-1 attenuated LPS-induced alterations in Ca 2+ regulation. The elevated reactive oxygen species levels observed in LPS-challenged myocytes were suppressed after PCD-1 treatment. The protein levels of NF-κB and IL-6 increased following LPS treatment. Decreased sarcoplasmic/endoplasmic reticulum Ca 2+ ATPase 2a protein levels were observed in LPS-challenged cardiomyocytes. PCD-1 modulates LPS-induced alterations in inflammatory and Ca 2+ regulatory protein levels. Our results suggest that PCD-1 modulates LPS-induced alterations in intracellular Ca 2+ and Na  +  homeostasis, reactive oxygen species production, and the NF-κB inflammatory pathway in atrial cardiomyocytes., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Chih-Yuan Lin reports article publishing charges, equipment, drugs, or supplies, statistical analysis, and writing assistance were provided by Ministry of Science and Technology of Taiwan. Hsiang-Yu Yang reports article publishing charges, equipment, drugs, or supplies, statistical analysis, and writing assistance were provided by Ministry of National Defense Medical Affairs Bureau. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

LL37 alone and in complex with self-DNA triggers inflammatory responses in myeloid cells and plays a crucial role in the development of systemic autoimmune diseases, like psoriasis and systemic lupus erythematosus. We demonstrated that LL37/self-DNA complexes induce long-term metabolic and epigenetic changes in monocytes, enhancing their responsiveness to subsequent stimuli. Monocytes trained with LL37/self-DNA complexes and those derived from psoriatic patients exhibited heightened glycolytic and oxidative phosphorylation rates, elevated release of proinflammatory cytokines, and affected naïve CD4 + T cells. Additionally, KDM6A/B, a demethylase of lysine 27 on histone 3, was upregulated in psoriatic monocytes and monocytes treated with LL37/self-DNA complexes. Inhibition of KDM6A/B reversed the trained immune phenotype by reducing proinflammatory cytokine production, metabolic activity, and the induction of IL-17-producing T cells by LL37/self-DNA-treated monocytes. Our findings highlight the role of LL37/self-DNA-induced innate immune memory in psoriasis pathogenesis, uncovering its impact on monocyte and T cell dynamics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Liver-expressed antimicrobial peptide 2 (LEAP-2) has been recently identified as the endogenous non-competitive allosteric antagonist of the growth hormone secretagogue receptor 1a (GHSR1a). In rodents, LEAP-2 blunts ghrelin-induced feeding and its plasma levels are modulated in response to nutritional status, being decreased upon fasting and increased in high-fat diet (HFD) fed mice. Clinical data support the regulation of circulating LEAP-2 by nutrient availability in humans. In this work, our primary objective was to examine the chronic effects of ghrelin and LEAP-2 administration on food intake, adiposity, and energy expenditure in young mice subjected to standard and HFD at both room temperature and at thermoneutrality. Furthermore, we aimed to assess the impact of these two hormones on aging mice., Results: Our results indicate that LEAP-2 produces a significant decrease of body weight and adiposity, an increase in energy expenditure, and activation of the thermogenic program in white and brown adipose tissue depots. However, this effect is not maintained under HFD or under thermoneutral conditions and is only partially observed in aging mice., Conclusion: In summary our studies describe the central effects of LEAP-2 within distinct experimental contexts, and contribute to the comprehension of LEAP-2's role in energy metabolism., (© 2024. The Author(s).)

Concerns regarding toxicity and resistance of current drugs in visceral leishmaniasis have been reported. Antimicrobial peptides are considered to be promising candidates and among them human cathelicidin hCAP18/LL-37 showed significant parasite killing on drug-sensitive and resistant Leishmania promastigotes, in addition to its apoptosis-inducing role. Administration of hCAP18/LL-37 to infected macrophages also decreased parasite survival and increased the host favorable cytokine interleukin 12. However, 1,25-dihydroxyvitamin D3 (vitamin D3)-induced endogenous hCAP18/LL-37 production was hampered in infected THP-1 cells. Infection also suppressed the vitamin D3 receptor (VDR), transcription factor of hCAP18/LL-37. cAMP response element modulator (CREM), the repressor of VDR, was induced in infection, resulting in suppression of both VDR and cathelicidin expression. PGE2/cAMP/PKA axis was found to regulate CREM induction during infection and silencing CREM in infected cells and BALB/c mice led to decreased parasite survival. This study documents the antileishmanial potential of cathelicidin and further identifies CREM as a repressor of cathelicidin in Leishmania infection., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Psoriasis is a noncontagious auto-inflammatory chronic skin disease. So far, some of the inflammatory genes were upregulated in mouse model of psoriasis. This study examined changes in skin mRNA expression of L-kynureninase ( Kynu ), cathelicidin antimicrobial peptide ( Camp ), beta-defensin 2 ( Defb2 ), and proenkephalin ( Penk ) in a mouse model of imiquimod-induced psoriasis., Materials and Methods: Tree groups of C57BL/6 female mice were allocated. The imiquimod (IMQ) cream was administered to the mice dorsal skin of the two groups to induce psoriatic inflammation. In the treatment group, IMQ was administered 10 min after hydrogel-containing M7 anti-IL-17A aptamer treatment. Vaseline (Vas) was administered to the negative control group. The psoriatic skin lesions were evaluated based on the psoriasis area severity index (PASI) score, histopathology, and mRNA expression levels of Kynu , Camp , Defb2 , and Penk using real-time PCR. In order to assess the systemic response, the spleen and lymph node indexes were also evaluated., Results: The PASI and epidermal thickness scores were 6.01 and 1.96, respectively, in the IMQ group, and they significantly decreased after aptamer administration to 1.15 and 0.90, respectively ( P < 0.05). Spleen and lymph node indexes showed an increase in the IMQ group, followed by a slight decrease after aptamer treatment ( P > 0.05). Additionally, the mRNA expression levels of Kynu , Defb2 , Camp , and Penk genes in the IMQ-treated region showed a significant 2.70, 4.56, 3.29, and 2.61-fold increase relative to the Vas mice, respectively ( P < 0.05). The aptamer-treated region exhibited a significant decrease in these gene expression levels ( P < 0.05). A positive correlation was found between Kynu , Penk , and Camp expression levels and erythema, as well as Camp expression with PASI, scaling, and thickness ( P < 0.05)., Conclusion: According to our results, it seems that Kynu , Camp , and Penk can be considered appropriate markers for the evaluation of psoriasis in IMQ-induced psoriasis. Also, the anti-IL-17 aptamer downregulated these important genes in this mouse model., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this article., (Copyright © 2024 Zahra Emami et al.)

To reduce food spoilage and deterioration caused by microbial contamination, antimicrobial peptides (AMPs) have gradually gained attention as a biological preservative. Odorranain-C1 is an α-helical cationic antimicrobial peptide extracted from the skin of frogs with broad-spectrum antimicrobial activity. In this study, we achieved the expression of Odorranain-C1 in Pichia pastoris (P. pastoris) (also known as Komagataella phaffii) by employing DNA recombination technology. The recombinant Odorranain-C1 showed broad-spectrum antibacterial activity and displayed a minimum inhibitory concentration within the range of 8-12 μg.mL -1 . Meanwhile, Odorranain-C1 exhibited superior stability and lower hemolytic activity. Mechanistically, Odorranain-C1 disrupted the bacterial membrane's integrity, ultimately causing membrane rupture and subsequent cell death. In tilapia fillets preservation, Odorranain-C1 inhibited the total colony growth and pH variations, while also reducing the production of total volatile basic nitrogen (TVB-N) and thiobarbituric acid (TBA). In conclusion, these studies demonstrated the efficient recombinant expression of Odorranain-C1 in P. pastoris, highlighting its promising utilization in food preservation., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Chunming Dong reports financial support was provided by National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: To investigate the role of NEAT1 targeted regulation of miR-125/ADAM9 mediated NF-κB pathway in inflammatory response in rosacea., Method: HaCaT cell rosacea phenotype was induced by LL37. The connection targeted by NEAT1 and miR-125a-5p was confirmed by Double-Luciferase report analysis. qPCR was employed to assess the levels of expression for NEAT1, miR-125a-5p, and ADAM9 genes. The levels of expression for ADAM9/TLR2/NF-κB P65 pathway proteins in each batch of cells were determined by Western blotting. The levels of expression for inflammatory factors, including TNF-α, IL-1β, IL-6, and IL-18, were measured through ELISA experimentation., Results: LL37 could successfully induce HaCaT cells to exhibit rosacea phenotype. The luciferase report experiment confirmed that NEAT1 could target and bind miR-125a-5p and inhibit its expression. ADAM9 exhibited increased expression in LL37-induced HaCaT cells, showing a positive association with NEAT1 expression and inverse relationship with miR-125a-5p activation. LL37 treatment promoted the expression of ADAM9/TLR2/NF-κB P65 pathway proteins. Silencing ADAM9 can inhibit the inflammatory signaling pathway and reduce the level of TNF-α, IL-1β, IL-6, and IL-18 in HaCaT cells., Conclusion: NEAT1 can suppress the production of miR-125a-5p and activate the TLR2/NF-κB inflammatory pathway mediated by ADAM9, thereby promoting the inflammatory response in rosacea., (© 2024 The Author(s). Skin Research and Technology published by John Wiley & Sons Ltd.)

Liver-expressed antimicrobial peptide 2 (LEAP2) and ghrelin have reciprocal effects on their common receptor, the growth hormone secretagogue receptor (GHSR). Ghrelin is considered a gastric hormone and LEAP2 a liver-derived hormone and both have been proposed to be involved in the pathophysiology of obesity and type 2 diabetes (T2D). We investigated the mRNA expression of LEAP2, ghrelin and GHSR along the intestinal tract of individuals with and without TD2, and in the liver of men with and without obesity. Mucosal biopsies retrieved with 30-cm intervals throughout the small intestine and from 7 well-defined locations along the large intestine from 12 individuals with T2D and 12 healthy controls together with liver biopsies from 15 men with obesity and 15 lean men were subjected to bulk transcriptomics analysis. Both in individuals with and without T2D, mRNA expression of LEAP2 increased through the small intestine until dropping at the ileocecal valve, with little LEAP2 mRNA expression in the large intestine. Pronounced LEAP2 expression was observed in the liver of men with and without obesity. Robust ghrelin mRNA expression was observed in the duodenum of individuals with and without T2D, gradually decreasing along the small intestine with little expression in the large intestine. Ghrelin mRNA expression was not detected in the liver biopsies, and GHSR mRNA expression was not. In conclusion, we provide unique mRNA expression profiles of LEAP2, ghrelin and GHSR along the human intestinal tract showing no T2D-associated changes, and in the liver showing no differences between men with and without obesity., Competing Interests: Declaration of Competing Interest A.E has nothing to declare. H.G.V has received research support from Zealand Pharma. M.P.S and, L.S.G have nothing to declare. T.V. has served on scientific advisory panels or speakers’ bureaus or has served as a consultant to or received research support from Amgen, AstraZeneca, BMS, Boehringer Ingelheim, Eli Lilly, Gilead, Merck Sharp & Dohme, Mundipharma, Novo Nordisk, Sanofi, and SunPharma. F.K.K. is employed by Novo Nordisk A/S as of December 1st, 2023. Before joining Novo Nordisk A/S, F.K.K. has served on scientific advisory panels and/or been part of speaker’s bureaus for, served as a consultant to, and/or received research support from 89bio, Amgen, AstraZeneca, Boehringer Ingelheim, Carmot Therapeutics, Eli Lilly, Gubra, MedImmune, MSD/Merck, Mundipharma, Norgine, Novo Nordisk, Sanofi, Zealand Pharma and Zucara., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of end-stage liver disease associated with increased mortality and cardiovascular disease. Obesity and diabetes are the most important risk factors of MASLD. It is well-established that obesity-associated insulin resistance leads to a situation of tissue lipotoxicity characterized by an accumulation of excess fat in non-fat tissues such as the liver, promoting the development of MASLD, and its progression into metabolic dysfunction-associated steatohepatitis., Methods: Here, we aimed to review the impact of disrupted intestinal permeability, antimicrobial proteins and bacterial endotoxin in the development and progression of MASLD., Results and Conclusion: Recent studies demonstrated that obesity- and obesogenic diets-associated alterations of intestinal microbiota along with the disruption of intestinal barrier integrity, the alteration in antimicrobial proteins and, in consequence, an enhanced translocation of bacterial endotoxin into bloodstream might contribute to this pathological process through to impacting liver metabolism and inflammation., (© 2024 The Authors. European Journal of Clinical Investigation published by John Wiley & Sons Ltd on behalf of Stichting European Society for Clinical Investigation Journal Foundation.)

Lasioglossin-III (LL-III) is a potent broad-spectrum antimicrobial peptide used in diverse antimicrobial applications. In this work, coarse-grained and all-atom molecular dynamics simulation strategies were used in tandem to interpret the molecular mechanisms involved in the interfacial dynamics of LL-III and its recombinant variants during interactions with diverse cell membrane systems. Our results indicate that the membrane charges act as the driving force for initiating the membrane-peptide interactions, while the hydrophobic or van der Waals forces help to reinforce the membrane-peptide bindings. The optimized charge-hydrophobicity ratio of the LL-III peptides helps ensure their high specificity toward bacterial membranes compared to mammalian membrane systems, which also helps explain our experimental observations. Overall, we hope that our work gives new insight into the antimicrobial action of LL-III peptides and that the adopted simulation strategy will help other scientists and engineers extract maximal information from complex molecular simulations using minimal computational power.

The human cathelicidin LL-37 shows activity against microorganisms, but it is also cytotoxic to host cells. The CAMP gene codes for the LL-37 precursor hCAP18 which is processed extracellularly to active LL-37. It has previously been shown that vitamin D stimulates CAMP gene activity, but less information is available demonstrating that vitamin D also can increase hCAP18/LL-37 protein production. Here, we show with RT-qPCR that a physiological concentration of vitamin D (50 nM) enhances CAMP mRNA levels by about 170 times in human THP-1 monocyte cells. Stimulation with 50 nM vitamin D increases hCAP18/LL-37 protein contents 3-4 times in THP-1 cell lysates demonstrated by both dot blot analysis and ELISA applying two different hCAP18/LL-37 antibodies. Treatment with the proteasome inhibitor MG132 enhances hCAP18/LL-37 levels, suggesting that turnover of hCAP18/LL-37 protein is regulated by the proteasome. The hCAP18/LL-37 concentration in vitamin D-stimulated THP-1 cells corresponds to 1.04 μM LL-37. Interestingly, synthetic LL-37, at this concentration, reduces viability of human osteoblast-like MG63 cells, whereas the THP-1 cells are less sensitive as demonstrated by the MTT assay. In summary, we show that vitamin D enhances hCAP18/LL-37 production, and that this effect can be of physiological/pathophysiological relevance for LL-37-induced human osteoblast toxicity., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Bengt-Olof Nilsson reports financial support was provided by The Gyllenstiernska Krapperupsstiftelsen. Bengt-Olof Nilsson reports financial support was provided by The Alfred Österlund Foundation. Alexandra Aidoukovitch reports financial support was provided by The Swedish Dental Society. Elisabeth Bankell reports financial support was provided by The Royal Physiographic Society. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Innate immunity of invertebrates offers potent antimicrobial peptides (AMPs) against drug-resistant infections. To identify new worm β-hairpin AMPs, we explored the sequence diversity of proteins with a BRICHOS domain, which comprises worm AMP precursors. Strikingly, we discovered new BRICHOS AMPs not in worms, but in caecilians, the least studied clade of vertebrates. Two precursor proteins from Microcaecilia unicolor and Rhinatrema bivittatum resemble SP-C lung surfactants and bear worm AMP-like peptides at C-termini. The analysis of M. unicolor tissue transcriptomes shows that the AMP precursor is highly expressed in the lung along with regular SP-C, suggesting a different, protective function. The peptides form right-twisted β-hairpins, change conformation upon lipid binding, and rapidly disrupt bacterial membranes. Both peptides exhibit broad-spectrum activity against multidrug-resistant ESKAPE pathogens with 1-4 μM MICs and remarkably low toxicity, giving 40-70-fold selectivity towards bacteria. These BRICHOS AMPs, previously unseen in vertebrates, reveal a novel lung innate immunity mechanism and offer a promising antibiotics template., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ruslan Smetanin, Olga Shamova and Igor Eliseev have patent pending to Institute of Experimental Medicine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Diabetic retinopathy (DR) is characterized by chronic, low-grade inflammation. This state may be related to the heightened production of neutrophil extracellular traps (NETs) induced by high glucose (HG). Human cathelicidin antimicrobial peptide (LL37) is an endogenous ligand of G protein-coupled chemoattractant receptor formyl peptide receptor 2 (FPR2), expressed on neutrophils and facilitating the formation and stabilization of the structure of NETs. In this study, we detected neutrophils cultured under different conditions, the retinal tissue of diabetic mice, and fibrovascular epiretinal membranes (FVM) samples of patients with proliferative diabetic retinopathy (PDR) to explore the regulating effect of LL37/FPR2 on neutrophil in the development of NETs during the process of DR. Specifically, HG or NG with LL37 upregulates the expression of FPR2 in neutrophils, induces the opening of mitochondrial permeability transition pore (mPTP), promotes the increase of reactive oxygen species and mitochondrial ROS, and then leads to the rise of NET production, which is mainly manifested by the release of DNA reticular structure and the increased expression of NETs-related markers. The PI3K/AKT signaling pathway was activated in neutrophils, and the phosphorylation level was enhanced by FPR2 agonists in vitro. In vivo, increased expression of NETs markers was detected in the retina of diabetic mice and in FVM, vitreous fluid, and serum of PDR patients. Transgenic FPR2 deletion led to decreased NETs in the retina of diabetic mice. Furthermore, in vitro, inhibition of the LL37/FPR2/mPTP axis and PI3K/AKT signaling pathway decreased NET production induced by high glucose. These results suggested that FPR2 plays an essential role in regulating the production of NETs induced by HG, thus may be considered as one of the potential therapeutic targets., (© 2024 Federation of American Societies for Experimental Biology.)

Glioblastoma, the most aggressive form of brain cancer, poses a significant global health challenge with a considerable mortality rate. With the predicted increase in glioblastoma incidence, there is an urgent need for more effective treatment strategies. In this study, we explore the potential of caerin 1.1 and 1.9, host defence peptides derived from an Australian tree frog, in inhibiting glioblastoma U87 and U118 cell growth. Our findings demonstrate the inhibitory impact of caerin 1.1 and 1.9 on cell growth through CCK8 assays. Additionally, these peptides effectively curtail the migration of glioblastoma cells in a cell scratch assay, exhibiting varying inhibitory effects among different cell lines. Notably, the peptides hinder the G0/S phase replication in both U87 and U118 cells, pointing to their impact on the cell cycle. Furthermore, caerin 1.1 and 1.9 show the ability to enter the cytoplasm of glioblastoma cells, influencing the morphology of mitochondria. Proteomics experiments reveal intriguing insights, with a decrease in CHI3L1 expression and an increase in PZP and JUNB expression after peptide treatment. These proteins play roles in cell energy metabolism and inflammatory response, suggesting a multifaceted impact on glioblastoma cells. In conclusion, our study underscores the substantial anticancer potential of caerin 1.1 and 1.9 against glioblastoma cells. These findings propose the peptides as promising candidates for further exploration in the realm of glioblastoma management, offering new avenues for developing effective treatment strategies., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Wang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Monocytes are the primary targets of Zika virus (ZIKV) and are associated with ZIKV pathogenesis. Currently, there is no effective treatment for ZIKV infection. It is known that 1,25-dihydroxy vitamin D 3  (VitD3) has strong antiviral activity in dengue virus-infected macrophages, but it is unknown whether VitD3 inhibits ZIKV infection in monocytes. We investigated the relationship between ZIKV infection and the expression of genes of the VitD3 pathway, as well as the inflammatory response of infected monocytes in vitro. ZIKV replication was evaluated using a plaque assay, and VitD3 pathway gene expression was analyzed by RT-qPCR. Pro-inflammatory cytokines/chemokines were quantified using ELISA. We found that VitD3 did not suppress ZIKV replication. The results showed a significant decrease in the expression of vitamin D3 receptor (VDR), cytochrome P450 family 24 subfamily A member 1 (CYP24A1), and cathelicidin antimicrobial peptide (CAMP) genes upon ZIKV infection. Treatment with VitD3 was unable to down-modulate production of pro-inflammatory cytokines, except TNF-α, and chemokines. This suggests that ZIKV infection inhibits the expression of VitD3 pathway genes, thereby preventing VitD3-dependent inhibition of viral replication and the inflammatory response. This is the first study to examine the effects of VitD3 in the context of ZIKV infection, and it has important implications for the role of VitD3 in the control of viral replication and inflammatory responses during monocyte infection., (© 2024. The Author(s).)

The innate immune system provides a crucial first line of defense against invading pathogens attacking the body. As the only member of the human cathelicidin family, the antimicrobial peptide LL-37 has been shown to have antiviral, antifungal, and antibacterial properties. In complexation with nucleic acids, LL-37 is suggested to maintain its beneficial health effects while also acting as a condensation agent for the nucleic acid. Complexes formed by LL-37 and nucleic acids have been shown to be immunostimulatory with a positive impact on the human innate immune system. However, some studies also suggest that in some circumstances, LL-37/nucleic acid complexes may be a contributing factor to autoimmune disorders such as psoriasis and systemic lupus erythematosus. This review provides a comprehensive discussion of research highlighting the beneficial health effects of LL-37/nucleic acid complexes, as well as discussing observed detrimental effects. We will emphasize why it is important to investigate and elucidate structural characteristics, such as condensation patterns of nucleic acids within complexation, and their mechanisms of action, to shed light on the intricate physiological effects of LL-37 and the seemingly contradictory role of LL-37/nucleic acid complexes in the innate immune response., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Rosacea is a chronic facial inflammatory skin disease that occurs with dysfunction of the immune system. Colchicine was reported to have anti-inflammatory properties. However, the impact of colchicine on rosacea remains unclear. In the present study, the phenotype of rosacea lesions was evaluated by the redness score, inflammatory biomarkers were analyzed by reverse transcription PCR (RT‒PCR), and the infiltration of inflammatory cells was assessed by IHC analysis and immunofluorescence in a rosacea-like mouse model. In vitro, RT‒PCR was used to identify the inflammatory factors that Toll-like receptor 2 (TLR2) agonist caused neutrophils to produce, and immunofluorescence and coimmunoprecipitation were used to identify putative signalling pathways. We found that skin erythema and histopathological alterations, as well as elevated proinflammatory factors (IL-1β, IL-6, TNFα, CXCL2) and CAMP, were significantly ameliorated by colchicine treatment in LL37-induced rosacea-like mice. In addition, colchicine reduced the colocalization of TLR2 and neutrophils and the formation of neutrophil extracellular trap networks (NET) in mouse lesions. In neutrophils, colchicine markedly reduced TLR2 agonist-induced inflammatory biomarker expression, NET formation, and ROS production. Moreover, we found that LL37 could bind to TLR2 upon activation of TLR2 in neutrophils. Importantly, colchicine could repress the combination of TLR2 and LL37 in vivo. Finally, bioinformatics methods further validated the key molecules of neutrophil-related inflammation in rosacea, which is consistent with our experimental findings. Collectively, colchicine ameliorated rosacea-like dermatitis by regulating the neutrophil immune response activated by the TLR2 pathway, indicating that it could be an effective therapeutic option for patients with rosacea., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Macins are a family of antimicrobial peptides, which play multiple roles in the elimination of invading pathogens. In the present study, a macin was cloned and characterized from Pacific abalone Haliotis discus hannai (Designated as HdMac). Analysis of the conserved domain suggested that HdMac was a new member of the macin family. In non-stimulated abalones, HdMac transcripts were constitutively expressed in all five tested tissues, especially in hemocytes. After Vibrio harveyi stimulation, the expression of HdMac mRNA in hemocytes was significantly up-regulated at 12 hr (P < 0.01). RNAi-mediated knockdown of HdMac transcripts affected the survival rates of abalone against V. harveyi. Moreover, recombinant protein of HdMac (rHdMac) exhibited high antibacterial activities against invading bacteria, especially for Vibrio anguillarum. In addition, rHdMac possessed binding activities towards glucan, lipopolysaccharides (LPS), and peptidoglycan (PGN), but not chitin in vitro. Membrane integrity analysis revealed that rHdMac could increase the membrane permeability of bacteria. Meanwhile, both the phagocytosis and chemotaxis ability of hemocytes could be significantly enhanced by rHdMac. Overall, the results showed that HdMac could function as a versatile molecule involved in immune responses of H. discus hannai., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Rosacea is a chronic and psychologically ladened disease affecting 1%-3% of people worldwide. The identification and validation of biomarkers in rosacea patients has the potential to improve disease progression, support diagnosis, provide objective measures for clinical trials and aid in management. The objective of this review is to systematically identify all rosacea biomarkers, categorize them by type and identify trends to improve disease expression. Eligibility criteria for this review (PROSPERO CRD42023397510) include randomized controlled trials, case-control studies, cohort studies and other observational studies. No restrictions were placed on patient demographics (age, sex, ethnicity) or language of publication until February 2023. Quality of studies was assessed using the National Institute of Health quality assessment tool. The literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A total of 805 unique articles were screened based on the applied inclusion and exclusion criteria. After the articles were screened based on title/abstract and full-text, a total of 38 studies were included, reporting on a total of 119 unique biomarkers. The results of this review and current rosacea pathogenic mechanisms provide the greatest support for the innate cathelicidin and inflammasome, T h 1 and T h 17 pathways. The most commonly reported biomarkers include IL-1β, TNF-α, IL-37, IFN-γ and MMP-9. Biomarkers identified in this study support current theories of rosacea pathogenesis and provide direction for research to further our knowledge. However, more research is needed to identify biomarkers panels that can provide diagnostic utility. This may be difficult due to the heterogeneity of the disease and potential differences between rosacea subtypes., (© 2023 The Authors. Journal of the European Academy of Dermatology and Venereology published by John Wiley & Sons Ltd on behalf of European Academy of Dermatology and Venereology.)

The intestine defends against pathogenic microbial invasion via the secretion of host defense peptides (HDPs). Nutritional immunomodulation can stimulate the expression of endogenous HDPs and enhance the body's immune defense, representing a novel non-antibiotic strategy for disease prevention. The project aims to explore the regulatory mechanism of protegrin-1 (PG-1) expression using sodium phenylbutyrate (PBA) by omics sequencing technology and further investigate the role of key regulatory genes on intestinal health. The results showed that PBA promoted PG-1 expression in intestinal epithelial cells based on cell density through epidermal growth factor receptor (EGFR) and G protein-coupled receptor (GPR43). Transcriptome sequencing and microRNA sequencing revealed that C-X-C motif chemokine receptor 2 (CXCR2) exhibited interactions with PG-1. Pre-treatment cells with a CXCR2 inhibitor (SB225002) effectively suppressed the induction of PG-1 by PBA. Furthermore, SB225002 significantly suppressed the gene expression of HDPs in the jejunum of mice without influencing on the morphology, number of goblet cells, and proliferation of the intestine. CXCR2 inhibition significantly reduced the expression of HDPs during E. coli infection, and resulted in the edema of jejunal epithelial cells. The 16S rDNA analysis of cecal contents showed that the E. coli and SB225002 treatments changed gut microbiota diversity and composition at different taxonomic levels. Correlation analysis suggested a potential regulatory relationship between gut microbiota and HDPs. To that end, a gene involved in the HDP expression, CXCR2, has been identified in the study, which contributes to improving intestinal immune function. PBA may be used as a functional additive to regulate intestinal mucosal function, thereby enhancing the health of the intestinal and host., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Proline-rich antimicrobial peptides (PrAMPs) inhibit bacterial protein biosynthesis by binding to the polypeptide exit tunnel (PET) near the peptidyl transferase center. Api137, an optimized derivative of honeybee PrAMP apidaecin, inhibits protein expression by trapping release factors (RFs), which interact with stop codons on ribosomes to terminate translation. This study uses cryo-EM, functional assays and molecular dynamic (MD) simulations to show that Api137 additionally occupies a second binding site near the exit of the PET and can repress translation independently of RF-trapping. Api88, a C-terminally amidated (-CONH 2 ) analog of Api137 (-COOH), binds to the same sites, occupies a third binding pocket and interferes with the translation process presumably without RF-trapping. In conclusion, apidaecin-derived PrAMPs inhibit bacterial ribosomes by multimodal mechanisms caused by minor structural changes and thus represent a promising pool for drug development efforts., (© 2024. The Author(s).)

Antimicrobial peptides (AMPs) are an essential part of the vertebrate innate immune system. Piscidins are a family of AMPs specific in fish. In our previous investigation, we identified four paralogous genes of piscidins in the orange-spotted grouper (Epinephelus coicodes), which exhibited distinct activities against bacteria, fungi, and parasitic ciliated protozoa. Piscidins demonstrated their capability to modulate the expression of diverse immune-related genes; however, their precise immunoregulatory functions remain largely unexplored. In this study, we examined the immunomodulatory properties of putative mature peptides derived from four E. coicodes piscidins (ecPis1S, ecPis2S, ecPis3S, and ecPis4S) in head kidney leukocytes (HKLs) or monocytes/macrophages (MO/MΦ)-like cells isolated from E. coicodes. Our data demonstrate that E. coicodes piscidins exhibit immunomodulatory activities supported by multiple lines of evidence. Firstly, all four piscidins displayed chemotactic activities towards HKLs, with the most potent chemotactic activity observed in ecPis2S. Secondly, stimulation with E. coicodes piscidins enhanced respiratory burst and phagocytic activity in MO/MФ-like cells, with ecPis3S showing the highest efficacy in increasing phagocytosis of MO/MΦ-like cells. Thirdly, mRNA expression levels of chemokine receptors, Toll-like receptors, T cell receptors, and proinflammatory cytokines were modulated to varying extents by the four piscidins in E. coicodes HKLs. Overall, our findings indicate that the immunological activities of these four paralogous piscidins from E. coicodes are exhibited in a paralog-specific and concentration-dependent manner, highlighting their distinct and versatile immunomodulatory properties. This study makes a significant contribution to the field of fish AMPs immunology by elucidating the novel mechanisms through which members of the piscidin family exert their immunomodulatory effects. Moreover, it provides valuable insights for further exploration of fish immunomodulating agents., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background/aim: Oral epithelial cells serve as the primary defense against microbial exposure in the oral cavity, including the fungus Candida albicans. Dectin-1 is crucial for recognition of β-glucan in fungi. However, expression and function of Dectin-1 in oral epithelial cells remain unclear., Materials and Methods: We assessed Dectin-1 expression in Ca9-22 (gingiva), HSC-2 (mouth), HSC-3 (tongue), and HSC-4 (tongue) human oral epithelial cells using flow cytometry and real-time polymerase chain reaction. Cell treated with β-glucan-rich zymosan were evaluated using real-time polymerase chain reaction. Phosphorylation of spleen-associated tyrosine kinase (SYK) was analyzed by western blotting., Results: Dectin-1 was expressed in all four cell types, with high expression in Ca9-22 and HSC-2. In Ca9-22 cells, exposure to β-glucan-rich zymosan did not alter the mRNA expression of chemokines nor of interleukin (IL)6, IL8, IL1β, IL17A, and IL17F. Zymosan induced the expression of antimicrobial peptides β-defensin-1 and LL-37, but not S100 calcium-binding protein A8 (S100A8) and S100A9. Furthermore, the expression of cylindromatosis (CYLD), a negative regulator of nuclear factor kappa B (NF-κB) signaling, was induced. In HSC-2 cells, zymosan induced the expression of IL17A. The expression of tumor necrosis factor alpha-induced protein 3 (TNFAIP3), a negative regulator of NF-κB signaling, was also induced. Expression of other cytokines and antimicrobial peptides remained unchanged. Zymosan induced phosphorylation of SYK in Ca9-22 cells, as well as NF-κB., Conclusion: Oral epithelial cells express Dectin-1 and recognize β-glucan, which activates SYK and induces the expression of antimicrobial peptides and negative regulators of NF-κB, potentially maintaining oral homeostasis., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background: Capsular contracture is the most common complication following breast implant placement. Cathelicidin LL-37 is a cationic peptide involved in innate immunity. Initially investigated for its antimicrobial role, it was found to have pleiotropic activities, such as immunomodulation, angiogenesis stimulation, and tissue healing. The aim of the study was to investigate the expression and localization of LL-37 in human breast implant capsules and its relationship with capsular formation, remodeling, and clinical outcomes., Methods: The study enrolled 28 women (29 implants) who underwent expander substitution with definitive implant. Contracture severity was evaluated. Specimens were stained with hematoxylin and eosin, Masson trichrome, immunohistochemistry, and immunofluorescence for LL-37, CD68, α-smooth muscle actin, collagen type I and type III, CD31, and Toll-like receptor-4., Results: LL-37 was expressed in macrophages and myofibroblasts of capsular tissue in 10 (34%) and nine (31%) of the specimens, respectively. In eight cases (27.5%), it was expressed by both macrophages and myofibroblasts of the same specimen. In infected capsules, expression by both cell types was found in all (100%) specimens. LL-37 expression by myofibroblasts positively correlated with its expression by macrophages ( P < 0.001). Moreover, LL-37 expression by macrophages of periexpander capsules negatively correlated with the severity of capsular contracture on definitive implants ( P = 0.04)., Conclusions: This study demonstrates the expression of LL-37 in macrophages and myofibroblasts of capsular tissue and its negative correlation with the severity of capsular contracture following permanent implant placement. Expression or up-regulation of LL-37 may be involved in myofibroblast and macrophage modulation, thus playing a role in the pathogenic fibrotic process underlying capsular contracture., Clinical Relevance Statement: This is the first study to demonstrate LL37 expression in capsular tissue and to hypothesize its role in contracture and as a prognostic marker for contracture severity. If confirmed, medical strategies or implant coating could be implemented to reduce the risk of contracture for high-risk patients., (Copyright © 2023 by the American Society of Plastic Surgeons.)

Background: Vitamin D plays a vital role in modulating both innate and adaptive immune systems. Therefore, vitamin D deficiency has been associated with higher levels of autoimmune response and increased susceptibility to infections. CYP27B1 encodes a member of the cytochrome P450 superfamily of enzymes. It is instrumental in the conversion of circulating vitamin D (calcifediol) to active vitamin D (calcitriol). This is a crucial step for macrophages to express Cathelicidin Anti-microbial Peptide ( CAMP ), an anti-bacterial factor released during the immune response. Our recent study indicated that a Crohn's disease (CD)-associated pathogen known as Mycobacterium avium paratuberculosis (MAP) decreases vitamin D activation in macrophages, thereby impeding cathelicidin production and MAP infection clearance. The mechanism by which MAP infection exerts these effects on the vitamin D metabolic axis remains elusive., Methods: We used two cell culture models of THP-1 macrophages and Caco-2 monolayers to establish the effects of MAP infection on the vitamin D metabolic axis. We also tested the effects of Calcifediol, Calcitriol, and SB203580 treatments on the relative expression of the vitamin D metabolic genes, oxidative stress biomarkers, and inflammatory cytokines profile., Results: In this study, we found that MAP infection interferes with vitamin D activation inside THP-1 macrophages by reducing levels of CYP27B1 and vitamin D receptor ( VDR ) gene expression via interaction with the TLR2-dependent p38/MAPK pathway. MAP infection exerts its effects in a time-dependent manner, with the maximal inhibition observed at 24 h post-infection. We also demonstrated the necessity to have toll-like receptor 2 (TLR2) for MAP infection to influence CYP27B1 and CAMP expression, as TLR2 gene knockdown resulted in an average increase of 7.78 ± 0.88 and 13.90 ± 3.5 folds in their expression, respectively. MAP infection also clearly decreased the levels of p38 phosphorylation and showed dependency on the p38/MAPK pathway to influence the expression of CYP27B1 , VDR , and CAMP which was evident by the average fold increase of 1.93 ± 0.28, 1.86 ± 0.27, and 6.34 ± 0.51 in their expression, respectively, following p38 antagonism. Finally, we showed that calcitriol treatment and p38/MAPK blockade reduce cellular oxidative stress and inflammatory markers in Caco-2 monolayers following macrophage-mediated MAP infection., Conclusions: This study characterized the primary mechanism by which MAP infection leads to diminished levels of active vitamin D and cathelicidin in CD patients, which may explain the exacerbated vitamin D deficiency state in these cases.