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The global surge in multi-drug resistant bacteria, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli has led to a growing need for new antibacterial compounds. Despite being promising, the potential of fish-derived antimicrobial peptides (AMPs) in combating ESBL-producing E. coli is largely unexplored. In this study, native African catfish antimicrobial peptides (NACAPs) were extracted from the skin mucus of farmed African catfish, Clarias gariepinus, using a combination of 10% acetic acid solvent hydrolysis, 5 kDa ultrafiltration, and C18 hydrophobic interaction chromatography. Peptides were then sequenced using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The identified peptides were screened for potential antibacterial activity using Random Forest and AdaBoost machine learning algorithms. The most promising peptide was chemically synthesized and evaluated in vitro for safety on rabbit red blood cells and activity against ESBL-producing E. coli (ATCC 35218) utilizing spot-on-lawn and broth dilution methods. Eight peptides ranging from 13 to 22 amino acids with molecular weights between 968.42 and 2434.11 Da were identified. Peptide NACAP-II was non-hemolytic to rabbit erythrocytes (p > 0.05) with a zone of inhibition (ZOI) of 22.7 ± 0.9 mm and a minimum inhibitory concentration (MIC) of 91.3 ± 1.2 μg/mL. The peptide is thus a candidate antibacterial compound with enormous potential applications in the pharmaceutical industry. However, further studies are still required to establish an upscale production strategy and optimize its activity and safety in vivo.

Positive membrane tension in the stretched plasma membrane of cells and in the stretched lipid bilayer of vesicles has been well analyzed quantitatively, whereas there is limited quantitative information on negative membrane tension in compressed plasma membranes and lipid bilayers. Here, we examined negative membrane tension quantitatively. First, we developed a theory to describe negative membrane tension by analyzing the free energy of lipid bilayers to obtain a theoretical equation for negative membrane tension. This allowed us to obtain an equation describing the negative membrane tension (σosm) for giant unilamellar vesicles (GUVs) in hypertonic solutions due to negative osmotic pressure (Π). Then, we experimentally estimated the negative membrane tension for GUVs in hypertonic solutions by measuring the rate constant (kr) of rupture of the GUVs induced by the constant tension (σex) due to an external force as a function of σex. We found that larger σex values were required to induce the rupture of GUVs under negative Π compared with GUVs in isotonic solution and quantitatively determined the negative membrane tension induced by Π (σosm) by the difference between these σex values. At small negative Π, the experimental values of negative σosm agree with their theoretical values within experimental error, but as negative Π increases, the deviation increases. Negative tension increased the stability of GUVs because higher tensions were required for GUV rupture, and the rate constant of antimicrobial peptide magainin 2-induced pore formation decreased. [ABSTRACT FROM AUTHOR]

Purpose: To study the therapeutic effect of hemagglutinin-2 and fimbrial (HA2-FimA) vaccine on experimental periodontitis in rats. Materials and Methods: The first batch of rats was divided into two groups and immunised with pure water or pVAX1-HA2- FimA at the age of 6, 7, and 9 weeks. After sacrificing the animals, total RNA was extracted from the spleens for RNA high-throughput sequencing (RNA-Seq) analysis. The second batch of rats was divided into four groups (A, B, C, D), and an experimental periodontitis rat model was established by suturing silk thread around the maxillary second molars of rats in groups B, C, and D for 4 weeks. The rats were immunised with pure water, pVAX1-HA2-FimA vaccine, empty pVAX1 vector, and pure water at 10, 11, and 13 weeks of age, respectively. Secretory immunoglobulin A (SIgA) antibodies and cathelicidin antimicrobial peptide (CAMP) levels in saliva were measured by enzyme-linked immunosorbent assay (ELISA). All rats were euthanised at 17 weeks of age, and alveolar bone loss was examined using micro-computed tomography (Micro-CT). Results: Through sequencing analysis, six key genes, including Camp, were identified. Compared with the other three groups, the rats in the periodontitis+pVAX1-HA2-FimA vaccine group showed higher levels of SIgA and CAMP (p < 0.05). MicroCT results showed significantly less alveolar bone loss in the periodontitis+pVAX1-HA2-FimA vaccine group compared to the periodontitis+pVAX1 group and periodontitis+pure water group (p < 0.05). Conclusion: HA2-FimA DNA vaccine can increase the levels of SIgA and CAMP in the saliva of experimental periodontitis model rats and reduce alveolar bone loss. [ABSTRACT FROM AUTHOR]

The mouse pathogen Citrobacter rodentium is utilized as a model organism for studying infections caused by the human pathogens enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) and to elucidate mechanisms of mucosal immunity. In response to C. rodentium infection, innate lymphoid cells and T cells secrete interleukin (IL)-22, a cytokine that promotes mucosal barrier function. IL-22 plays a pivotal role in enabling mice to survive and recover from C. rodentium infection, although the exact mechanisms involved remain incompletely understood. Here, we investigated whether particular components of the host response downstream of IL-22 contribute to the cytokine's protective effects during C. rodentium infection. In line with previous research, mice lacking the IL-22 gene (Il22-/- mice) were highly susceptible to C. rodentium infection. To elucidate the role of specific antimicrobial proteins modulated by IL-22, we infected the following knockout mice: S100A9-/- (calprotectin), Lcn2-/- (lipocalin-2), Reg3b-/- (Reg3β), Reg3g-/- (Reg3γ), and C3-/- (C3). All knockout mice tested displayed a considerable level of resistance to C. rodentium infection, and none phenocopied the lethality observed in Il22-/- mice. By investigating another arm of the IL-22 response, we observed that C. rodentium-infected Il22-/- mice exhibited an overall decrease in gene expression related to intestinal barrier integrity as well as significantly elevated colonic inflammation, gut permeability, and pathogen levels in the spleen. Taken together, these results indicate that host resistance to lethal C. rodentium infection may depend on multiple antimicrobial responses acting in concert, or that other IL-22-regulated processes, such as tissue repair and maintenance of epithelial integrity, play crucial roles in host defense to attaching and effacing pathogens.

Mammalian hosts combat bacterial infections through the production of defensive cationic antimicrobial peptides (CAPs). These immune factors are capable of directly killing bacterial invaders; however, many pathogens have evolved resistance evasion mechanisms such as cell surface modification, CAP sequestration, degradation, or efflux. We have discovered that several pathogenic and commensal proteobacteria, including the urgent human threat Neisseria gonorrhoeae, secrete a protein (lactoferrin-binding protein B, LbpB) that contains a low-complexity anionic domain capable of inhibiting the antimicrobial activity of host CAPs. This study focuses on a cattle pathogen, Moraxella bovis, that expresses the largest anionic domain of the LbpB homologs. We used an exhaustive biophysical approach employing circular dichroism, biolayer interferometry, cross-linking mass spectrometry, microscopy, size-exclusion chromatography with multi-angle light scattering coupled to small-angle X-ray scattering (SEC-MALS-SAXS), and NMR to understand the mechanisms of LbpB-mediated protection against CAPs. We found that the anionic domain of this LbpB displays an α-helical secondary structure but lacks a rigid tertiary fold. The addition of antimicrobial peptides derived from lactoferrin (i.e. lactoferricin) to the anionic domain of LbpB or full-length LbpB results in the formation of phase-separated droplets of LbpB together with the antimicrobial peptides. The droplets displayed a low rate of diffusion, suggesting that CAPs become trapped inside and are no longer able to kill bacteria. Our data suggest that pathogens, like M. bovis, leverage anionic intrinsically disordered domains for the broad recognition and neutralization of antimicrobials via the formation of biomolecular condensates.

It is unclear how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to the strong but ineffective inflammatory response that characterizes severe Coronavirus disease 2019 (COVID-19), with amplified immune activation in diverse cell types, including cells without angiotensin-converting enzyme 2 receptors necessary for infection. Proteolytic degradation of SARS-CoV-2 virions is a milestone in host viral clearance, but the impact of remnant viral peptide fragments from high viral loads is not known. Here, we examine the inflammatory capacity of fragmented viral components from the perspective of supramolecular self-organization in the infected host environment. Interestingly, a machine learning analysis to SARS-CoV-2 proteome reveals sequence motifs that mimic host antimicrobial peptides (xenoAMPs), especially highly cationic human cathelicidin LL-37 capable of augmenting inflammation. Such xenoAMPs are strongly enriched in SARS-CoV-2 relative to low-pathogenicity coronaviruses. Moreover, xenoAMPs from SARS-CoV-2 but not low-pathogenicity homologs assemble double-stranded RNA (dsRNA) into nanocrystalline complexes with lattice constants commensurate with the steric size of Toll-like receptor (TLR)-3 and therefore capable of multivalent binding. Such complexes amplify cytokine secretion in diverse uninfected cell types in culture (epithelial cells, endothelial cells, keratinocytes, monocytes, and macrophages), similar to cathelicidins role in rheumatoid arthritis and lupus. The induced transcriptome matches well with the global gene expression pattern in COVID-19, despite using

Intestinal transplantation is the definitive treatment for intestinal failure. However, tissue rejection and graft-versus-host disease are relatively common complications, necessitating aggressive immunosuppression that can itself pose further complications. Tracking intraluminal markers in ileal effluent from standard ileostomies may present a noninvasive and sensitive way to detect developing pathology within the intestinal graft. This would be an improvement compared to current assessments, which are limited by poor sensitivity and specificity, contributing to under or over-immunosuppression, respectively, and by the need for invasive biopsies. Herein, we report an approach to reproducibly analyze ileal fluid obtained through stoma sampling for antimicrobial peptide/protein concentrations, reasoning that these molecules may provide an assessment of intestinal homeostasis and levels of intestinal inflammation over time. Concentrations of lysozyme (LYZ), myeloperoxidase (MPO), calprotectin (S100A8/A9) and β-defensin 2 (DEFB2) were assessed using adaptations of commercially available enzyme-linked immunosorbent assays (ELISAs). The concentration of α-defensin 5 (DEFA5) was assessed using a newly developed sandwich ELISA. Our data support that with proper preparation of ileal effluent specimens, precise and replicable determination of antimicrobial peptide/protein concentrations can be achieved for each of these target molecules via ELISA. This approach may prove to be reliable as a clinically useful assessment of intestinal homeostasis over time for patients with ileostomies.

Cathelicidin-RC1, extracted from the bullfrog Rana catesbeiana , has been found to effectively combat gram-negative bacteria but has limited inhibitory effects on gram-positive bacteria. Additionally, the specific mechanism of cathelicidin-RC1's interaction with bacteria remains unclear. In this research, we present the expression analysis of a chimeric peptide composed of three repetitive units of cathelicidin-RC1 (3×cathelicidin-RC1) with a hemagglutinin (HA) and a 6×His tag attached at its C-terminus in Chlamydomonas reinhardtii , leading to the production of a chimeric peptide with a molecular mass of ∼16.2 kDa. The recombinant peptide, 3×cathelicidin-RC1-HA-6×His, demonstrates a wide range of antimicrobial activity, with minimum inhibitory concentration (MIC) values of approximately 20–30 µg/ml and 10–60 µg/ml against gram-positive and negative bacteria, respectively. The minimum bactericidal concentration (MBC) values of 3×cathelicidin-RC1-HA-6×His varies from 1× to 3×MIC. Furthermore, 3×cathelicidin-RC1-HA-6×His demonstrates excellent stability, pH stability, and resistance to digestion by certain proteases. It also exhibits low cytotoxicity and negligible hemolytic activity against rat erythrocytes. Scanning electron microscopy and propidium iodide analysis indicate that 3×cathelicidin-RC1-HA-6×His disrupts bacterial cell membranes, leading to inhibition of bacterial growth. Overall, our findings demonstrate that 3×cathelicidin-RC1-HA-6×His, produced in the heterologous expression host C. reinhardtii , effectively inhibits bacterial growth and holds great promise for potential application. [Display omitted] • A multimer termed 3×cathelicidin-RC1 was stably expressed in green algae. • 3×cathelicidin-RC1 has a broad spectrum of antibacterial activity. • 3×cathelicidin-RC1 was tolerant of temperature, pH, salt and certain proteinases. • 3×cathelicidin-RC1 showed a low toxicity and low hemolytic activity. • 3×cathelicidin-RC1 disrupted the integrity of the bacterial cell membrane. [ABSTRACT FROM AUTHOR]

Peptides are relatively small macromolecules, and their functionalities are usefully combined with organic or inorganic materials to design highly-efficient biomedical devices. Marine organisms are potential resources to identify a novel peptide with such functionalities, which can be employed to improve both of the inorganic and organic properties, essential for biomaterial design. This study reported and characterized a newly-found peptide, TO, derived from marine diatom, Thalassiosira oceanica. The peptide exhibited extraordinary dual functions: silica deposition and antimicrobial activity. It has not yet been reported that a peptide had both silica synthesis ability and antibacterial activity. When the peptide was incorporated into polyurethane (PU) foam, this dual-functionality was employed, and each function varied by peptide and silica precursor concentrations. In particular, the PU form (PU@mTO@SiO 2) with silica deposited by modified TO (mTO) showed increased water capacity by 200 %. Antimicrobial activities of PU@mTO@SiO 2 and control PU@SiO 2 (made w/o peptide) were evaluated against E. coli , P. aeruginosa , S. aureus , and B. subtilis. PU@mTO@SiO 2 exhibited significant antibacterial activity toward the tested bacteria. The TO or mTO peptide will facilitate the designing of novel biosilica-embedded materials or systems with antimicrobial activity required in the biomedical field. [Display omitted] • mTO peptide from marine diatom was characterized as a novel dual-functional peptide. • mTO peptide showed a high silicification activity and antimicrobial activity. • mTO-incorporated polyurethane (PU) foam showed dual-functionalities. • Such biosilica-embedded materials with antimicrobial activity will be useful in biomedical field. [ABSTRACT FROM AUTHOR]

Antibacterial agents play a crucial role in healthcare and public health by combating bacterial infections. However, the emergence of antibiotic resistance necessitates a deeper understanding of 6 their mechanisms of action. This review explores the use of spectroscopic techniques, including UV-Vis, FTIR, NMR, Raman spectroscopy, mass spectrometry, and fluorescence spectroscopy, to elucidate the mechanisms of action (MOA) of antibacterial agents in the period from 2003 to 2024. The review discusses how these techniques can elucidate the MOA of classical antibiotics, antiseptics and antimicrobial peptides. Since these spectroscopic techniques provide valuable insights into the molecular interactions between antibacterial agents and bacteria, offering a comprehensive understanding of their mechanisms at a molecular level. By studying electronic transitions, chemical bond vibrations, metabolomics, and protein interactions, researchers can gain in-depth knowledge of antibacterial MOAs. This knowledge can inform the development of improved treatments and strategies to combat bacterial resistance, leading to better patient outcomes and global public health. [ABSTRACT FROM AUTHOR]

Chronic wounds can develop as a result of prolonged inflammation during the healing process, which can happen due to bacterial infection. Therefore, preventing infection and controlling inflammation can accelerate wound healing. Antimicrobial peptides have different protective properties in addition to antimicrobial activity. Some of these activities include the stimulation of cytokine or chemokine synthesis, the facilitation of chemotaxis and cell proliferation, the acceleration of cell proliferation, the induction of anti-inflammatory responses, and the promotion of wound repair. This study aimed to assess the wound healing potential of a novel in silico-designed antimicrobial peptide. Then, its anti-inflammatory activity was investigated by measuring the level of tumor necrosis factor-α (TNF-α) and transforming growth factor beta (TGF-β) as indicators of the wound healing process. In addition, the influence of the peptide on cell migration was evaluated by a scratch test on human dermal fibroblasts (HDF) and HaCaT cells as a human epidermal keratinocyte cell line. The results showed that our new peptide could act well in inhibiting TNF-α over-secretion while increasing the expression of TGF-β as an anti-inflammatory factor. This peptide showed a significant potential to stimulate HDF and HaCaT cell migration and proliferation. Therefore, using this peptide as an anti-inflammatory component of wound dressings may be promising. • A novel antimicrobial peptide was designed from Cathelicidine-2, named as mCHTL (131-140). • The mCHTL (131-140) could inhibit TNF-α over-secretion. • The mCHTL (131-140) could increase the TGF-β expression. • The mCHTL (131-140) could stimulate HDF and HaCaT cells migration and proliferation. [ABSTRACT FROM AUTHOR]

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. We sought to identify the molecular etiology of the downregulated expression of HTN1. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Antimicrobial peptide (AMP), also called host defense peptide, is a part of the innate immune system in eukaryotic organisms. AMPs are also produced by prokaryotes in response to stressful conditions and environmental changes. They have a broad spectrum of activity against both Gram positive and Gram negative bacteria. They are also effective against viruses, fungi, parasites, and cancer cells. AMPs are cationic or amphipathic in nature, but in recent years cationic AMPs have attracted a lot of attention because cationic AMPs can easily interact with negatively charged bacterial and cancer cell membranes through electrostatic interaction. AMPs can also eradicate bacterial biofilms and have broad-spectrum activity against multidrug resistant (MDR) bacteria. Although the main target site for AMPs is the cell membrane, they can also disrupt bacterial cell walls, interfere with protein folding and inhibit enzymatic activity. In recent centuries antibiotics are gradually losing their potential because of the continuous rise of antibiotic resistant bacteria. Therefore, there is an urgent need to develop novel therapeutic approaches to treat MDR bacteria, and AMP is such an alternative treatment option over conventional antibiotics. Several communicable diseases like tuberculosis and non-communicable diseases such as cancer can be treated by using AMPs. One of the major advantages of using AMP is that it works with high specificity and does not cause any harm to normal tissue. AMPs can be modified to improve their efficacy. In this narrative review, we are focusing on the potential application of AMPs in medical science. [ABSTRACT FROM AUTHOR]

Trimethyltin chloride (TMT) is a highly toxic organotin pollutant frequently found in aquatic environments, posing a significant threat to the ecological system. The kidney plays a vital role in the body's detoxification processes, and TMT present in the environment tends to accumulate in the kidneys. However, it remained unclear whether exposure to different doses of TMT could induce pyroptosis and immune dysfunction in grass carp kidney cells (CIK cells). For this purpose, after assessing the half‐maximal inhibitory concentration (IC50) of TMT on CIK cells, we established a model for exposure of CIK cells at varying concentrations of TMT. CIK cells were treated with various doses of TMT (2.5, 5, 10 μM) for 24 h. Oxidative stress levels were measured using kits and fluorescence methods, whereas the expression of related genes was verified through western blot and quantitative real‐time PCR (qRT‐PCR). The results indicated that TMT exposure led to oxidative stress, with increased levels of ROS, H2O2, MDA, and GSH, and inhibited activities of T‐AOC, SOD, and CAT. It activated the NF‐κB pathway, leading to the upregulation of NF‐κB p65, NF‐κB p50, GSDMD, NLRP3, ASC, and Caspase‐1. Furthermore, TMT exposure also resulted in increased expression of cytokines (IL‐18, IL‐6, IL‐2, IL‐1β, and TNF‐α) and decreased expression of antimicrobial peptides (LEAP2, HEPC, and β‐defensin). In summary, exposure to TMT induces dose‐dependent oxidative stress that activates the NF‐κB pathway, leading to pyroptosis and immune dysfunction in grass carp CIK cells. [ABSTRACT FROM AUTHOR]

Prevalent worldwide, the Androctonus scorpion genus contributes a vital role in scorpion envenoming. While diverse scorpionisms are observed because of several different species, their secretions to protect themselves have been identified as a potent source of antimicrobial peptide (AMP)‐like compounds. Distinctly, the venom of these species contains around 24 different AMPs, with definite molecules studied for their therapeutic potential as antimicrobial, antifungal, antiproliferative and antiangiogenic agents. Our review focuses on the therapeutic potential of native and synthetic AMPs identified so far in the Androctonus scorpion genus, identifying research gaps in peptide therapeutics and guiding further investigations. Certain AMPs have demonstrated remarkable compatibility to be prescribed as anticancer drug to reduce cancer cell proliferation and serve as a potent antibiotic alternative. Besides, analyses were performed to explore the characteristics and affinities of peptides for membranes. Overall, the study of AMPs derived from the Androctonus scorpion genus provides valuable insights into their potential applications in medicine and drug development. [ABSTRACT FROM AUTHOR]

Using activatable cell penetrating peptides (CPPs) are one of the most important strategies to overcome the low selectivity of CPPs by controlling the activity of positively charged CPPs through conjugation with a negatively charged sequence via an enzyme-mediated cleavable linker. In this study, anionic antimicrobial peptides are utilized as the negatively charged component of these activatable CPPs to gain an additional bioactive function such as selective anticancer therapy after activation by enzymatic cleavage. Without an enzyme, the bioactivities of both anionic and cationic components are mutually suppressed by electrostatic interaction within the intact peptide structure. After enzymatic cleavage, the electrostatic interactions between the negative and positive peptide fragments are disrupted, restoring the individual peptide bioactivities and leading to synergistic anticancer therapeutic efficacy. [ABSTRACT FROM AUTHOR]

Background Objectives Materials and Methods Results Conclusions and Clinical Relevance Canine superficial pyoderma is a common bacterial skin infection of dogs, generally caused by Staphylococcus pseudintermedius. The C4 strain of Staphylococcus felis was recently discovered to have strong antimicrobial activity against S. pseudintermedius in mice.We aimed to evaluate in vitro if this antimicrobial activity was maintained using a novel canine skin explant model.Punch biopsies (8 mm) of skin from recently euthanised dogs were collected and placed into six‐well plates on top of an agarose pedestal.Histological examination of the skin explants showed an intact dermal–epidermal organisation and a stratum corneum that was successfully colonised by S. pseudintermedius after topical application. The number of colony forming units of S. pseudintermedius showed a 2 log increase after 24 h colonisation, indicating that the explant supported bacterial growth. By contrast, co‐treatment with S. felis C4 live bacteria and its sterile protein product significantly reduced the growth of a methicillin‐susceptible (ST540, p = 0.0357) and a methicillin‐resistant (MR) strain (ST71, p = 0.0143) of S. pseudintermedius. No detectable bacteria were recovered from or visualised on skin 24 h posttreatment with the S. felis C4 sterile protein product.Using a novel canine explant model, we demonstrate that the S. felis C4 strain inhibits the growth of S. pseudintermedius and that it is a promising candidate for a new probiotic therapy to treat cutaneous infections caused by S. pseudintermedius, including MR strains. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis is a keystone pathogen for periodontal disease. The bacteria are black-pigmented and require heme for growth. P. gingivalis exhibit resistance to many antimicrobial peptides, which contributes to their success in the oral cavity. P. gingivalis W50 was resistant to the antimicrobial peptide LGL13K but susceptible to the all-D-amino acid stereoisomer, DGL13K. Upon prolonged exposure to DGL13K, a novel non-pigmented mutant was isolated. Exposure to the L-isomer, LGL13K, did not produce a non-pigmented mutant. The goal of this study was to characterize the genomic and cellular changes that led to the non-pigmented phenotype upon treatment with DGL13K. The non-pigmented mutant showed a low minimum inhibitory concentration and two-fold extended minimum duration for killing by DGL13K, consistent with tolerance to this peptide. The DGL13K-tolerant bacteria exhibited synonymous mutations in the hagA gene. The mutations did not prevent mRNA expression but were predicted to alter mRNA structure. The non-pigmented bacteria were deficient in hemagglutination and hemoglobin binding, suggesting that the HagA protein was not expressed. This was supported by whole cell enzyme-linked immunosorbent assay and gingipain activity assays, which suggested the absence of HagA but not of two closely related gingipains. In vivo virulence was similar for wild type and non-pigmented bacteria in the Galleria mellonella model. The results suggest that, unlike LGL13K, DGL13K can defeat multiple bacterial resistance mechanisms but bacteria can gain tolerance to DGL13K through mutations in the hagA gene. [ABSTRACT FROM AUTHOR]

Background: Single-domain von Willebrand factor type C (SVWC) constitute a protein family predominantly identified in arthropods, characterized by a SVWC domain and involved in diverse physiological processes such as host defense, stress resistance, and nutrient metabolism. Nevertheless, the physiological mechanisms underlying these functions remain inadequately comprehended. Results: A massive expansion of the SVWC gene family in Musca domestica (MdSVWC) was discovered, with a count of 35. MdSVWC1 was selected as the representative of the SVWC family for functional analysis, which led to the identification of the immune function of MdSVWC1 as a novel pattern recognition receptor. MdSVWC1 is highly expressed in both the fat body and intestines and displays acute induction upon bacterial infection. Recombinant MdSVWC1 binds to surfaces of both bacteria and yeast through the recognition of multiple pathogen-associated molecular patterns and exhibits Ca2+-dependent agglutination activity. MdSVWC1 mutant flies exhibited elevated mortality and hindered bacterial elimination following bacterial infection as a result of reduced hemocyte phagocytic capability and weakened expression of antimicrobial peptide (AMP) genes. In contrast, administration of recombinant MdSVWC1 provided protection to flies from bacterial challenges by promoting phagocytosis and AMP genes expression, thereby preventing bacterial colonization. MdSPN16, a serine protease inhibitor, was identified as a target protein of MdSVWC1. It was postulated that the interaction of MdSVWC1 with MdSPN16 would result in the activation of an extracellular proteolytic cascade, which would then initiate the Toll signaling pathway and facilitate the expression of AMP genes. Conclusions: MdSVWC1 displays activity as a soluble pattern recognition receptor that regulates cellular and humoral immunity by recognizing microbial components and facilitating host defense. [ABSTRACT FROM AUTHOR]

Anophelinae mosquitoes are exposed to a variety of microbes including Plasmodium parasites that cause malaria. When infected, mosquitoes mount versatile immune responses, including the production of antimicrobial peptides. Cecropins are one of the most widely distributed families of antimicrobial peptides in insects and all previously studied Anopheles members are playing roles in adult mosquito immunity. We have identified and characterized a novel member of the Anopheles gambiae cecropin family, cecropin D (CecD), that is uniquely expressed and immune-responsive at late larval stages to promote microbial clearance through its broad-spectrum antibacterial activity during larval-pupal developmental transition. Interestingly, Cecropin D also exhibited highly potent activity against Plasmodium falciparum sporozoites, the malaria parasite stage that is transmitted from mosquitoes and infects humans and thereby holds promise as a malaria transmission-blocking agent. Finally, we have defined unequivocal cecropin-specific molecular signatures to systematically organize the diversity of the cecropin family in malaria vectors. Author summary: Anopheles mosquitoes that transmit the deadly malaria are exposed to a variety of microbes in their natural habitats. Mosquitoes use their innate immune system that also comprises antimicrobial peptides to fight infections with these microbes including the Plasmodium malaria parasite. Cecropins are one of the most widely distributed antimicrobial peptides in insects and all previously studied Anopheles cecropins are playing roles in adult mosquito immunity. We have identified and characterized a novel Anopheles gambiae cecropin, cecropin D (CecD), that is uniquely produced and immune-responsive at late larval stages to promote broad spectrum microbial clearance during larval-pupal developmental transition. Interestingly, Cecropin D also shows potent activity against Plasmodium falciparum sporozoites, the malaria parasite stage that is transmitted from mosquitoes to humans and could therefore be developed into a malaria control strategy. [ABSTRACT FROM AUTHOR]

Antibacterial bone cements (ABCs), such as antibiotic-loaded bone cements (ALBCs), have been widely utilized in clinical treatments. Currently, bone cements loaded with vancomycin, gentamicin, tobramycin, or clindamycin are approved by the US Food and Drug Administration. However, traditional ALBCs exhibit drawbacks like burst release and bacterial resistance. Therefore, there is a demand for the development of antibacterial bone cements containing novel agents to address these defects. In this review, we provide an overview and prospect of the new antibacterial agents that can be used or have the potential to be applied in bone cement, including metallic antibacterial agents, pH-switchable antibacterial agents, cationic polymers, N-halamines, non-leaching acrylic monomers, antimicrobial peptides and enzymes. Additionally, we have conducted a preliminary assessment of the feasibility of bone cement containing N-halamine, which has demonstrated good antibacterial activities. The conclusion of this review is that the research and utilization of bone cement containing novel antibacterial agents contribute to addressing the limitations of ALBCs. Therefore, it is necessary to continue expanding the research and use of bone cement incorporating novel antibacterial agents. This review offers a novel perspectives for designing ABCs and treating bone infections. [ABSTRACT FROM AUTHOR]

Bovine milk peptides are the protein fragments with diverse bioactive properties having antioxidant, anticarcinogenic, other therapeutic and nutraceutical potentials. These peptides are formed in milk by enzymatic hydrolysis, gastrointestinal digestion and fermentation processes. They have significant health impact with high potency and low toxicity making them a suitable natural alternative for preventing and managing diseases. Antibiotic resistance has increased the quest for better peptide candidates with antimicrobial effects. This article presents a comprehensive review on well documented antimicrobial, immunological, opioid, and anti-hypertensive activities of bovine milk peptides. It also covers the usage of computational biology tools and databases for prediction and analysis of the food-derived bioactive peptides. In silico analysis of amino acid sequences of Bos taurus milk proteins have been predicted to generate peptides with dipeptidyl peptidase IV inhibitory and ACE inhibitory properties, making them favorable candidates for developing blood sugar lowering drugs and anti-hypertensives. In addition to the prediction of new bioactive peptides, application of bioinformatics tools to predict novel functions of already known peptides is also discussed. Overall, this review focuses on the reported as well as predicted biologically active peptide of casein and whey proteins of bovine milk that can be utilized to develop therapeutic agents. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs), naturally occurring components of innate immunity, are emerging as a promising new class of anticancer agents. This review explores the potential of AMPs as a novel class of anticancer agents. AMPs, naturally occurring peptides with broad-spectrum antimicrobial activity, exhibit several characteristics that make them attractive candidates for cancer therapy, including selectivity for cancer cells, broad-spectrum activity, and immunomodulatory effects. Analysis of a dataset of AMPs with anticancer activity reveals that their effectiveness is influenced by various structural properties, including net charge, length, Boman index, and hydrophobicity. These properties contribute to their ability to target and disrupt cancer cell membranes, interfere with intracellular processes, and modulate the immune response. The review highlights the promising potential of AMPs as a new frontier in cancer treatment, offering hope for more effective and less toxic therapies. AMPs demonstrate promising potential in cancer therapy through multiple mechanisms, including direct cytotoxicity, immune response modulation, and targeting of the tumor microenvironment, as evidenced by extensive preclinical studies in animal models showing tumor regression, metastasis inhibition, and improved survival rates. AMPs show significant potential as cancer therapeutics through their direct cytotoxicity, immune response modulation, and tumor microenvironment targeting, with promising results from preclinical studies and early-phase clinical trials. Future research should focus on optimizing AMP properties, developing novel delivery strategies, and exploring synergistic combination therapies to fully realize their potential as effective cancer treatments, while addressing challenges related to stability, delivery, and potential toxicity. [ABSTRACT FROM AUTHOR]

Phages and phage-encoded lytic enzymes are promising antimicrobial agents. In this study, we report the isolation and identification of bacteriophage KP2025 from Klebsiella pneumoniae. Bioinformatics analysis of KP2025 revealed a putative endolysin, LysKP213, containing a T4-like_lys domain. Purified LysKP213 was found to be highly thermostable, retaining approximately 44.4% of its lytic activity after 20 h of incubation at 95°C, and approximately 57.5% residual activity after 30 min at 121°C. Furthermore, when administered in combination with polymyxin B or fused at the N-terminus with the antimicrobial peptide cecropin A (CecA), LysKP213 exhibited increased antibacterial activity against Gram-negative pathogens, including K. pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli, both in vitro and in vivo. These results indicated that LysKP213 is a highly thermostable endolysin that, when combined with or fused with an outer membrane permeabilizer, has enhanced antibacterial activity and is a candidate agent for the control of infections by Gram-negative pathogens. [ABSTRACT FROM AUTHOR]

Introduction: Melittin is a potent antimicrobial peptide from bee venom that is effective against both Gram-positive and Gram-negative bacteria. However, it is extremely toxic to mammalian cells and, as yet, has no clinical use. Modifications to its amino acid sequence, cyclization, truncation, and dimerization have been attempted in order to reduce its toxicity whilst maintaining its antimicrobial activity. Methods: In this study, we targeted the three lysine residues present in melittin and substituted them with lysine homologs containing shorter side chains (ornithine, Orn, diaminobutyric acid, Dab, and diaminopropanoic acid, Dap) and made both parallel and antiparallel melittin dimers to observe how lysine substitution and dimerization affects its activity and toxicity. The antibacterial activity of melittin and its analogs was tested against S. aureus (Gram-positive bacteria) and E. coli (Gram-negative bacteria), and cytotoxicity was tested against the mammalian cell lines HEK293 and H4IIE. Results: Overall, dimerization and lysine substitution exhibited improved antimicrobial activity toward E. coli and limited improvement toward S. aureus. However, mammalian cell toxicity was only marginally reduced compared to native melittin. Interestingly, the parallel dimer was found to be marginally more active than the antiparallel dimer, indicating orientation maybe important for activity, although both dimers were less effective than the native and Lys-analog peptides toward S. aureus. Of the Lys substitutions, Dab and Dap improved melittin's activity toward E. coli. Discussion: Dimerization and Lys substitution of melittin improved the antimicrobial activity toward Gram-negative bacteria but did not significantly improve its activity toward Gram-positive bacteria. Some analogs also displayed reduced toxicity toward HEK293 and H4IIE cells but overall remained toxic at bactericidal concentrations. Our data indicates that although highly antibacterial, melittin's toxicity is the major drawback in its potential use. [ABSTRACT FROM AUTHOR]

Introduction: The human-derived amnion-chorion membrane (ACM) has endogenous antimicrobial properties, which are important for preventing the colonization and survival of oral bacteria on exposed membranes. This project aimed to decipher the underlying mechanism by identifying the components of ACM that confer antibacterial properties. In addition, the antimicrobial efficacy of these identified components on oral bacteria was assessed. Methods: Four antimicrobial proteins, histone H2A/H2B, cathelicidin LL-37, lactoferrin, and lysozyme, were identified via mass spectrometry in ACM. These proteins were then assessed for their efficacy in killing Streptococcus gordonii Challis. Log-phased bacterial cells were cultured with the commercially available proteins that were identified in ACM, either individually or in combination, at different concentrations. After incubation for 8 or 24 hours, the bacteria were stained with a live/dead viability kit and analyzed via confocal microscopy. Results: The combination of these proteins effectively killed S. gordonii in a dosedependent fashion after 8 or 24 hours of incubation. When each protein was tested individually, it killed S. gordonii at amuch lower efficacy relative to the combinations. The synergistic effects of the antimicrobial protein combinations were also observed in both the viable cell count recovery andminimum inhibitory concentration assays. Discussion: By shedding light on the mechanisms in the ACM's antimicrobial property, this study may raise more awareness of the potential benefit of utilization of a membrane with endogenous antimicrobial properties in regeneration surgeries. [ABSTRACT FROM AUTHOR]

Infection of native tissues or implanted devices is common, but clinical diagnosis is frequently difficult and currently available noninvasive tests perform poorly. Immunocompromised individuals (for example transplant recipients, or those with cancer) are at increased risk. No imaging test in clinical use can specifically identify infection, or accurately differentiate bacterial from fungal infections. Commonly used [18F]fluorodeoxyglucose (18FDG) positron emission computed tomography (PET/CT) is sensitive for infection, but limited by poor specificity because increased glucose uptake may also indicate inflammation or malignancy. Furthermore, this tracer provides no indication of the type of infective agent (bacterial, fungal, or parasitic). Imaging tools that directly and specifically target microbial pathogens are highly desirable to improve noninvasive infection diagnosis and localization. A growing field of research is exploring the utility of radiometals and their chelators (siderophores), which are small molecules that bind radiometals and form a stable complex allowing sequestration by microbes. This radiometal-chelator complex can be directed to a specific microbial target in vivo, facilitating anatomical localization by PET or single photon emission computed tomography. Additionally, bifunctional chelators can further conjugate therapeutic molecules (e.g., peptides, antibiotics, antibodies) while still bound to desired radiometals, combining specific imaging with highly targeted antimicrobial therapy. These novel therapeutics may prove a useful complement to the armamentarium in the global fight against antimicrobial resistance. This review will highlight current state of infection imaging diagnostics and their limitations, strategies to develop infection-specific diagnostics, recent advances in radiometal-based chelators for microbial infection imaging, challenges, and future directions to improve targeted diagnostics and/or therapeutics. [ABSTRACT FROM AUTHOR]

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. The antimicrobial resistance crisis calls for development of new classes of antibiotics. Here, authors use genome mining approach to discover a distinct family of ribosome-targeting proline rich antimicrobial peptides. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSIONS Yellow mealworm (Tenebrio molitor) larvae are increasingly recognized as a potential source of bioactive peptides due to their high protein content. Antimicrobial peptides from sustainable sources are a research topic of interest. This study aims to characterize the peptidome of T. molitor flour and an Alcalase‐derived hydrolysate, and to explore the potential presence of antimicrobial peptides using in silico analyses, including prediction tools, molecular docking and parameter correlations.T. molitor protein was hydrolysed using Alcalase, resulting in a hydrolysate (TMH10A) with a 10% degree of hydrolysis. The peptidome was analysed using LC‐TIMS‐MS/MS, yielding over 6000 sequences. These sequences were filtered using the PeptideRanker tool, selecting the top 100 sequences with scores >0.8. Bioactivity predictions indicated that specific peptides, particularly WLNSKGGF and GFIPYEPFLKKMMA, showed significant antimicrobial potential, particularly against bacteria, fungi and viruses. Correlations were found between antifungal activity and physicochemical properties such as net charge, hydrophobicity and isoelectric point.The study identified specific T. molitor‐derived peptides with strong predicted antimicrobial activity through in silico analysis. These peptides, particularly WLNSKGGF and GFIPYEPFLKKMMA, might offer potential applications in food safety and healthcare. Further experimental validation is required to confirm their efficacy. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

ABSTRACT Bioactive peptides (BAPs) have attracted considerable interest in scientific research due to their heterogeneity in sequence and structure, which underpins various biological functionalities. In this context, goat casein, an abundant by‐product of the dairy industry, emerges as a valuable source of BAPs. The present study undertook a meticulous evaluation of the bioactive potentials of goat casein‐derived peptides through an integrated approach combining computational simulations, high‐throughput screening, and molecular docking techniques. The initial phase involved the enzymatic digestion of goat milk casein using trypsin, followed by the identification of peptides via liquid chromatography–tandem mass spectrometry (LC–MS/MS), uncovering a total of 597 peptides. Subsequent prioritization using the PeptideRanker algorithm identified 70 peptides exhibiting potential bioactivity, as denoted by scores above 0.8. Advanced screening employing the BIOPEP database and the AutoDock and CAMPR4 tools facilitated the elucidation of 16 antioxidant, 59 hypotensive, 63 hypoglycemic, 70 hypolipidemic, and 25 antimicrobial peptides. Molecular docking studies further elucidated the spontaneous nature of the interactions between the peptides and their respective receptors, predominantly mediated by hydrogen bonding and hydrophobic interactions. Four peptides specifying all activities simultaneously were synthesized, and their activities were verified by in vitro experiments. These results not only highlight an effective strategy for the high‐throughput screening of goat casein‐derived peptides but also underscore the potential of utilizing casein as a viable source of functional food ingredients. This study thereby contributes significantly to the expanding field of functional food research, suggesting a sustainable approach to explore the potential of dairy by‐products. [ABSTRACT FROM AUTHOR]

The growth of bacteria and fungi may cause disease inf human or spoilage of food. New antimicrobial substances need to be discovered. Lactoferricin (LFcin) is a group of antimicrobial peptides derived from the N-terminal region of the milk protein lactoferrin (LF). LFcin has antimicrobial ability against a variety of microorganisms, which is significantly better than that of its parent version. Here, we review the sequences, structures, and antimicrobial activities of this family and elucidated the motifs of structural and functional significance, as well as its application in food. Using sequence and structural similarity searches, we identified 43 new LFcins from the mammalian LFs deposited in the protein databases, which are grouped into six families according to their origins (Primates, Rodentia, Artiodactyla, Perissodactyla, Pholidota, and Carnivora). This work expands the LFcin family and will facilitate further characterization of novel peptides with antimicrobial potential. Considering the antimicrobial effect of LFcin on foodborne pathogens, we describe the application of these peptides from the prospective of food preservation. [ABSTRACT FROM AUTHOR]

Biofilm infection and impaired healing of chronic wounds are posing tremendous challenges in clinical practice. In this study, we presented a versatile antimicrobial hydrogel capable of delivering nitric oxide (NO) in a controllable manner to dissipate biofilms, eliminate microorganisms, and promote the healing of chronic wounds. This hydrogel was constructed by Schiff-base crosslinking of oxidized dextran and antimicrobial peptide ε-poly-lysine, further encapsulating photothermal nanoparticles bearing NO donor. This hydrogel could continuously and slowly release NO, effectively dissipating biofilms, and promoting the proliferation of mouse fibroblasts and the migration of endothelial cells. Upon exposure to NIR laser irradiation, the hydrogel generated hyperthermia and rapidly released NO, resulting in the efficient elimination of a broad spectrum of drug-resistant Gram-positive/negative bacterial and fungal biofilms through the synergistic effects of NO, photothermal therapy, and the antibacterial peptide. Notably, the hydrogel demonstrated exceptional in vivo therapeutic outcomes in accelerating the healing process of mice diabetic wounds infected with methicillin-resistant Staphylococcus aureus by successfully eliminating biofilm infection, regulating inflammation, and facilitating angiogenesis and collagen deposition. Overall, this proposed hydrogel shows great promise in accommodating the various demands of the complex repair process of chronic wounds infected with biofilms. The presence of biofilm infections and underlying dysfunctions in the healing process made chronic wound become stuck in the inflammation stage and difficult to heal. This work developed a NIR laser-modulated three-stage NO-releasing versatile antimicrobial hydrogel (DEPN) exhibiting good therapeutic efficacy for chronic wound. This DEPN hydrogel could inherently and slowly released NO to disperse biofilm. Upon NIR laser irradiation, the DEPN hydrogel generated hyperthermia and induced a rapid burst release of NO effectively eliminating a broad spectrum of drug-resistant bacterial and fungal biofilms. Subsequently, the DEPN hydrogel continually release NO slowly to promote the tissue remolding. This DEPN hydrogel displays great potential in treatment of chronic wounds infected with biofilm. [Display omitted] [ABSTRACT FROM AUTHOR]

Introduction: This study investigated the interaction with membrane mimetic systems (LUVs), bacterial membranes, the CD spectra, and the bactericidal activity of two designed trematocine mutants, named Trem-HK and Trem-HSK. Mutants were constructed from the scaffold of Trematocine (Trem), a natural 22-amino acid AMP from the Antarctic fish Trematomus bernacchii, aiming to increase their positive charge. Methods: The selectivity of the designed AMPs towards bacterial membranes was improved compared to Trematocine, verified by their interaction with different LUVs and their membranolytic activity. Additionally, their a-helical conformation was not influenced by the amino acid substitutions. Our findings revealed a significant enhancement in antibacterial efficacy against ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae family) pathogens for both Trem-HK and Trem-HSK. Results: Firstly, we showed that the selectivity of the two new designed AMPs towards bacterial membranes was greatly improved compared to Trematocine, verifying their interaction with different LUVs and their membranolytic activity. We determined that their a-helical conformation was not influenced by the amino acid substitutions. We characterized the tested bacterial collection for resistance traits to different classes of antibiotics. The minimum inhibitory and bactericidal concentration (MIC and MBC) values of the ESKAPE collection were reduced by up to 80% compared to Trematocine. The bactericidal concentrations of Trematocine mutants showed important membranolytic action, evident by scanning electron microscopy, on all tested species. We further evaluated the cytotoxicity and hemolytic activity of the mutants. At 2.5 µM concentration, both mutants demonstrated low cytotoxicity and hemolysis, indicating selectivity towards bacterial cells. However, these effects increased at higher concentrations. Discussion: Assessment of in vivo toxicity using the Galleria mellonella model revealed no adverse effects in larvae treated with both mutants, even at concentrations up to 20 times higher than the lowest MIC observed for Acinetobacter baumannii, suggesting a high potential safety profile for the mutants. This study highlights the significant improvement in antibacterial efficacy achieved by increasing the positive charge of Trem-HK and Trem-HSK. This improvement was reached at the cost of reduced biocompatibility. Further research is necessary to optimize the balance between efficacy and safety for these promising AMPs. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are promising cationic and amphipathic molecules to fight antibiotic resistance. To search for novel AMPs, we applied a computational strategy to identify peptide sequences within the organisms' proteome, including in-house developed software and artificial intelligence tools. After analyzing 150.450 proteins from eight proteomes of bacteria, plants, a protist, and a nematode, nine peptides were selected and modified to increase their antimicrobial potential. The 18 resulting peptides were validated by bioassays with four pathogenic bacterial species, one yeast species, and two cancer cell-lines. Fourteen of the 18 tested peptides were antimicrobial, with minimum inhibitory concentrations (MICs) values under 10 µM against at least three bacterial species; seven were active against Candida albicans with MICs values under 10 µM; six had a therapeutic index above 20; two peptides were active against A549 cells, and eight were active against MCF-7 cells under 30 µM. This study's most active antimicrobial peptides damage the bacterial cell membrane, including grooves, dents, membrane wrinkling, cell destruction, and leakage of cytoplasmic material. The results confirm that the proposed approach, which uses bioinformatic tools and rational modifications, is highly efficient and allows the discovery, with high accuracy, of potent AMPs encrypted in proteins. [ABSTRACT FROM AUTHOR]

Protein aggregation is a common pathological occurrence in neurodegenerative diseases. This often leads to neuroinflammation, which exacerbates the aggregation and progression of diseases like Parkinson's and Alzheimer's. Here, we focus on immune responses and neurotoxicity in a Parkinson's disease model in Drosophila. Mutations in the SNCA gene that encodes the alpha (a)-Synuclein protein have been linked to familial Parkinson's disease, disrupting autophagy regulation in neuronal cells and promoting the formation of Lewy bodies, a hallmark of Parkinson's pathology. This results in the loss of dopaminergic neurons, manifesting as movement disorders. a-Synuclein aggregation triggers innate immune responses by activating microglial cells, leading to phagocytic activity and the expression of neuroprotective antimicrobial peptides (AMPs). However, sustained AMP expression or chronic inflammation resulting from inadequate microglial phagocytosis can induce neuronal toxicity and apoptosis, leading to severe dopaminergic neuron loss. This review underscores the mechanistic connection between immune response pathways and a-Synuclein-mediated neurodegeneration using Drosophila models. Furthermore, we extensively explore factors influencing neuroinflammation and key immune signaling pathways implicated in neurodegenerative diseases, particularly Parkinson's disease. Given the limited success of traditional treatments, recent research has focused on therapies targeting inflammatory signaling pathways. Some of these approaches have shown promising results in animal models and clinical trials. We provide an overview of current therapeutic strategies showing potential in treating neurodegenerative diseases, offering new avenues for future research and treatment development. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Objective Methods Results Conclusions Emerging evidence suggests a link between salivary metabolite changes and neurodegenerative dementia, with antimicrobial peptides (AMPs) implicated in its pathogenesis.We investigated the effects of a clinical oral rehabilitation programme tailored for dementia patients on salivary flow rate, AMP levels and oral health‐related quality of life (OHRQoL).Eligible patients were randomly assigned to either the experimental group (EG; n = 28) or the control group (CG; n = 27). Both groups received a leaflet on oral health. In addition, the EG received an oral care intervention that included individual lessons on oral muscle exercises and oral self‐care practices. Saliva samples and OHRQoL data were collected at baseline and follow‐up visits. Generalised estimating equation models were used to analyse the changes over time.At the 3‐month follow‐up, EG showed significantly lower histatin 5 (HTN‐5) levels (β = −0.08; effect size [ES] = 0.72) than CG. At 6 months, EG exhibited improved salivary flow rate (β = 0.89; ES = 0.89) and OHRQoL (β = 6.99; ES = 1.31) compared to CG. Changes in salivary flow rate (β = 4.03), HTN‐5 level (β = −0.78) and beta‐defensin 2 level (BD‐2) (β = −0.91) at 3 months predicted improved OHRQoL at 6 months (all p < 0.05).Our clinical oral rehabilitation programme reduced the level of salivary HTN‐5, increased salivary flow rate and enhanced OHRQoL in dementia patients. Furthermore, changes in salivary flow rate, HTN‐5 level and BD‐2 level were associated with improvements in patients' OHRQoL. [ABSTRACT FROM AUTHOR]

ABSTRACT Antimicrobial peptides (AMPs) are renowned for their broad‐spectrum efficacy against viruses, bacteria, and fungi, thereby holding promise for medicinal applications. Nisin, a bacteriocin synthesized by gram‐positive bacteria such as Lactobacillus and Streptococcus, has been used as a food preservative owing to its antimicrobial characteristics for decades. However, recent developments prompt further research on its application as therapeutic interventions, mainly focusing on anticancer activity. In line with this, the present study portrays the effects of nisin on human colorectal cancer cells and the underlying molecular mechanisms. A dose‐dependent decrease in cell viability with increasing concentrations of nisin was determined by the Alamar blue viability assay, which was supported by significant morphological changes in cells. Subsequently, we probed the apoptotic effects of nisin using EtBr/AO staining, confirming the induction of apoptosis upon nisin treatment, which was further confirmed by ELISA analysis. Elevated levels of Caspase 7 indicated increased apoptosis in nisin‐treated cells. As pharmaceutical p53 reactivation is considered as an attractive strategy to combat chemoresistance and adverse effects, the effect of nisin on p53 expression was determined by mRNA analysis. An upregulation in p53 expression in nisin‐treated cells compared to untreated controls suggests that bacterial nisin reactivates mutated p53. To assess cell cycle dynamics, we utilized PI flow cytometry, unveiling a G0/G1 phase arrest in nisin‐treated cells in contrast to untreated controls. In summary, our results strongly advocate the potential of nisin as a compelling candidate for drug development against colorectal cancer. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB), induced by Mycobacterium tuberculosis (Mtb) infection, remains a major public health issue worldwide. Mtb has developed complicated strategies to inhibit the immunological clearance of host cells, which significantly promote TB epidemic and weaken the anti-TB treatments. Host-directed therapy (HDT) is a novel approach in the field of anti-infection for overcoming antimicrobial resistance by enhancing the antimicrobial activities of phagocytes through phagosomal maturation, autophagy and antimicrobial peptides. Autophagy, a highly conserved cellular event within eukaryotic cells that is effective against a variety of bacterial infections, has been shown to play a protective role in host defense against Mtb. In recent decades, the introduction of nanomaterials into medical fields open up a new scene for novel therapeutics with enhanced efficiency and safety against different diseases. The active modification of nanomaterials not only allows their attractive targeting effects against the host cells, but also introduce the potential to regulate the host anti-TB immunological mechanisms, such as apoptosis, autophagy or macrophage polarization. In this review, we introduced the mechanisms of host cell autophagy for intracellular Mtb clearance, and how functional nanomaterials regulate autophagy for disease treatment. Moreover, we summarized the recent advances of nanomaterials for autophagy regulations as novel HDT strategies for anti-TB treatment, which may benefit the development of more effective anti-TB treatments. [ABSTRACT FROM AUTHOR]

The negative membrane potential within bacterial cells is crucial in various essential cellular processes. Sustaining a hyperpolarised membrane could offer a novel strategy to combat antimicrobial resistance. However, it remains uncertain which molecules are responsible for inducing hyperpolarization and what the underlying molecular mechanisms are. Here, we demonstrate that chemically diverse antimicrobial peptides (AMPs) trigger hyperpolarization of the bacterial cytosolic membrane when applied at subinhibitory concentrations. Specifically, these AMPs adopt a membrane-induced amphipathic structure and, thereby, generate hyperpolarization in Escherichia coli without damaging the cell membrane. These AMPs act as selective ionophores for K+ (over Na+) or Cl− (over H2PO4− and NO3−) ions, generating diffusion potential across the membrane. At lower dosages of AMPs, a quasi-steady-state membrane polarisation value is achieved. Our findings highlight the potential of AMPs as a valuable tool for chemically hyperpolarising bacteria, with implications for antimicrobial research and bacterial electrophysiology. Antimicrobial peptides with membrane-induced structure generate diffusion potential across the E. coli cytosolic membrane at subinhibitory concentrations. The differential ion permeability generates bacterial hyperpolarization. [ABSTRACT FROM AUTHOR]

This study aimed to increase the antifungal and insecticidal activities of NaD1, as an antimicrobial peptides (AMP), by improving its interaction with the fungal cell wall and chitin monomeric units in insect midguts. Hence, the chitin-binding domains (CBDs) of wheat germ agglutinin protein (WGA) were fused to either N- or C-terminus of NaD1 generating transgenic Nicotiana tabacum hairy roots (HRs). Molecular assessments confirmed the integration of NaD1 transgenes, their transcription and production of recombinant peptides in the HR lines. Total protein of (CBD)4-NaD1 and NaD1-(CBD)4 transgenic lines inhibited the growth of Pyricularia oryzae mycelium, suggesting that fusion of CBD to NaD1 can increase NaD1 half-life, leading to higher affinity toward cell wall chitin. Furthermore, feeding the third-instar larvae of Chilo suppressalis with both (CBD)4-NaD1 and NaD1-(CBD)4 extracts exhibited a higher mortality rate. Both NaD1-CBDs caused a significant decrease in trypsin (TRY) and chymotrypsin (CTR) activities in the larvae, while enhancing the activity of antioxidant enzymes CAT, POD, APX, and SOD. Therefore, feeding the larvae by total extract of NaD1-(CBD)4 and (CBD)4-NaD1 HR lines probably increased affinity to midgut chitin in C. suppressalis, enhancing insecticidal activities. Overall, the results indicate that recombinant peptides are effective in enhancing fungal and insect resistance. [ABSTRACT FROM AUTHOR]

Background: Our previous study revealed that feeding the antimicrobial peptide (AMP) product Scy-hepc significantly enhances the growth of mariculture fish through the activation of the GH-Jak2-STAT5-IGF1 axis. However, the contribution of gut microbiota to this growth enhancement remains unclear. This study aimed to elucidate the potential mechanism involved in intestinal absorption and modulation of gut microbiota in Epinephelus akaara following Scy-hepc feeding. Results: The results showed that a 35 day regimen of Scy-hpec markedly promoted the growth of E. akaara compared to groups supplemented with either florfenicol, B. subtilis, or a vector. The growth enhancement is likely attributed to alterations in microbiota colonization in the foregut and midgut, characterized by an increasing abundance of potential probiotics (Rhizobiaceae and Lysobacter) and a decreased abundance of opportunistic pathogens (Psychrobacter and Brevundimonas) as determined by 16S rRNA analysis. Additionally, similar to the effect of florfenicol feeding, Scy-hepc significantly improved host survival rate by over 20% in response to a lethal dose challenge with Edwardsiella tarda. Further investigations demonstrated that Scy-hepc is absorbed by the fish foregut (20–40 min) and midgut (20–30 min) as confirmed by Western blot, ELISA, and Immunofluorescence. The absorption of Scy-hepc affected the swimming, swarming and surfing motility of Vibrio harveyi and Bacillus thuringiensis isolated from E. akaara's gut. Moreover, Scy-hepc induced the downregulation of 40 assembly genes and the upregulation expression of 5, with the most significant divergence in gene expression between opportunistic pathogens and probiotics concentrated in their motility genes (PomA/B, MotA/B). Conclusions: In summary, this study shows that feeding AMP Scy-hepc can promote growth and bolster immunity in E. akaara. These beneficial effects are likely due to the absorption of Scy-hepc in the fish's foregut and midgut, which modulates the colonization and motility of commensal bacteria, leading to favorable changes in the composition of the foregut and midgut microbiota. Therefore, a profound understanding of the mechanisms by which antimicrobial peptides affect host gut microbiota will contribute to a comprehensive assessment of their advantages and potential application prospects as substitutes for antibiotics in fish health and improving aquaculture practices. [ABSTRACT FROM AUTHOR]

Multidrug-resistant Enterococcus faecium strains represent a major concern due to their ability to thrive in diverse environments and cause life-threatening infections. While antimicrobial resistance and virulence mechanisms have been extensively studied, the contribution of bacteriocins to E. faecium's adaptability remains poorly explored. E. faecium, within the Bacillota phylum, is a prominent bacteriocin producer. Here, we developed a tailored database of 76 Bacillota bacteriocins (217 sequences, including 40 novel bacteriocins) and applied it to uncover bacteriocin distribution patterns in 997 quality-filtered E. faecium and Enterococcus lactis (former E. faecium clade B) genomes. Curated using computational pipelines and literature mining, our database demonstrates superior precision versus leading public tools in identifying diverse bacteriocins. Distinct bacteriocin profiles emerged between E. faecium and E. lactis, highlighting species-specific adaptations. E. faecium strains from hospitalized patients were significantly enriched in bacteriocins as enterocin A and bacteriocins 43 (or T8), AS5, and AS11. These bacteriocin genes were strongly associated with antibiotic resistance, particularly vancomycin and ampicillin, and Inc18 rep2_pRE25-derivative plasmids, classically associated with vancomycin resistance transposons. Such bacteriocin arsenal likely enhances the adaptability and competitive fitness of E. faecium in the nosocomial environment. By combining a novel tailored database, whole-genome sequencing, and epidemiological data, our work elucidates meaningful connections between bacteriocin determinants, antimicrobial resistance, mobile genetic elements, and ecological origins in E. faecium and provides a framework for elucidating bacteriocin landscapes in other organisms. Characterizing species- and strain-level differences in bacteriocin profiles may reveal determinants of ecological adaptation, and translating these discoveries could further inform strategies to exploit bacteriocins against high-risk clones. IMPORTANCE This work significantly expands the knowledge on the understudied bacteriocin diversity in opportunistic enterococci, revealing their contribution in the adaptation to different environments. It underscores the importance of placing increased emphasis on genetic platforms carrying bacteriocins as well as on cryptic plasmids that often exclusively harbor bacteriocins since bacteriocin production can significant ly contribute to plasmid maintenance, potentially facilitating their stable transmission across generations. Further characterization of strain-level bacteriocin landscapes could inform strategies to combat high-risk clones. Overall, these insights provide a framework for unraveling the therapeutic and biotechnological potential of bacteriocins. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To survive in the host, pathogenic bacteria need to be able to react to the unfavorable conditions that they encounter, like low pH, elevated temperatures, antimicrobial peptides and many more. These conditions may lead to unfolding of envelope proteins and this may be lethal. One of the mechanisms through which bacteria are able to survive these conditions is through the protease/foldase activity of the high temperature requirement A (HtrA) protein. The gut pathogen Clostridioides difficile encodes one HtrA homolog that is predicted to contain a membrane anchor and a single PDZ domain. The function of HtrA in C. difficile is hitherto unknown but previous work has shown that an insertional mutant of htrA displayed elevated toxin levels, less sporulation and decreased binding to target cells. Here, we show that HtrA is membrane associated and localized on the surface of C. difficile and characterize the requirements for proteolytic activity of recombinant soluble HtrA. In addition, we show that the level of HtrA in the bacteria heavily depends on its proteolytic activity. Finally, we show that proteolytic activity of HtrA is required for survival under acidic conditions. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are emerging as a promising alternative to traditional antibiotics due to their ability to disturb bacterial membranes and/or their intracellular processes, offering a potential solution to the growing problem of antimicrobial resistance. AMP effectiveness is governed by factors such as net charge, hydrophobicity, and the ability to form amphipathic secondary structures. When properly balanced, these characteristics enable AMPs to selectively target bacterial membranes while sparing eukaryotic cells. This review focuses on the roles of positive charge, hydrophobicity, and structure in influencing AMP activity and toxicity, and explores strategies to optimize them for enhanced therapeutic potential. We highlight the delicate balance between these properties and how various modifications, including amino acid substitutions, peptide tagging, or lipid conjugation, can either enhance or impair AMP performance. Notably, an increase in these parameters does not always yield the best results; sometimes, a slight reduction in charge, hydrophobicity, or structural stability improves the overall AMP therapeutic potential. Understanding these complex interactions is key to developing AMPs with greater antimicrobial activity and reduced toxicity, making them viable candidates in the fight against antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are short, usually cationic peptides with an amphiphilic structure, which allows them to easily bind and interact with the cellular membranes of viruses, bacteria, fungi, and other pathogens. Bacterial AMPs, or bacteriocins, can be produced from Gram-negative and Gram-positive bacteria via ribosomal synthesis to eliminate competing organisms. Bacterial AMPs are vital in addressing the increasing antibiotic resistance of various pathogens, potentially serving as an alternative to ineffective antibiotics. Bacteriocins have a narrow spectrum of action, making them highly specific antibacterial compounds that target particular bacterial pathogens. This review covers the two main groups of bacteriocins produced by Gram-negative and Gram-positive bacteria, their modes of action, classification, sources of positive effects they can play on the human body, and their limitations and future perspectives as an alternative to antibiotics. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides represent a promising alternative to traditional drugs in relation to cost, toxicity, and, primarily, the growing problem of drug resistance. Here, we report on the activity against HSV-1 and HSV-2 of a previously described wide-spectrum synthetic decapeptide, Killer Peptide (KP). As determined by plaque reduction assays, treatment with KP at 100 μg/mL resulted in a reduction in the viral yield titer of 3.5 Logs for HSV-1 and 4.1 Logs for HSV-2. Further evaluation of KP antiviral activity focused on the early stages of the virus replicative cycle, including the determination of the residual infectivity of viral suspensions treated with KP. A direct effect of the peptide on viral particles impairing virus absorption and penetration was shown. The toxicity profile proved to be extremely good, with a selectivity index of 29.6 for HSV-1 and 156 for HSV-2. KP was also active against acyclovir (ACV)-resistant HSV isolates, while HSV subcultures in the presence of sub-inhibitory doses of KP did not lead to the emergence of resistant strains. Finally, the antiviral action of KP proved to be synergistic with that of ACV. Overall, these results demonstrate that KP could represent an interesting addition/alternative to acyclovir for antiviral treatment. [ABSTRACT FROM AUTHOR]

Ventilator-associated pneumonia (VAP) remains one of the most common hospital-acquired infections (HAI). Considering the complicated diagnosis and the lack of effective treatment, prophylactic measures are suggested as the new standard to prevent the disease. Although VAP often manifests a polymicrobial nature, Pseudomonas aeruginosa remains one of the pathogens associated with the highest morbidity and mortality rates within these mechanically ventilated patients. In this paper, we report on the development of an antibacterial hydrogel coating using the polymyxin B (PMB) peptide to prevent bacterial adhesion to the polymeric substrate. We fully characterized the properties of the coating using atomic force microscopy (AFM), scanning electron microscopy (SEM), wettability analyses and Fourier-transform infrared (FTIR) and Raman spectroscopy. Furthermore, several biological assays confirmed the antibacterial and anti-biofilm effect of the tubing for at least 8 days against P. aeruginosa. On top of that, the produced coating is compliant with the requirements regarding cytocompatibility stated in the ISO (International Organization for Standardization) 10993 guidelines and an extended release of PMB over a period of at least 42 days was detected. In conclusion, this study serves as a foundation for peptide-releasing hydrogel formulas in the prevention of VAP. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides take a specific position in the field of antibiotics (ATBs), however, from a large number of available molecules only a few of them were approved and are used in clinics. These therapeutic modalities play a crucial role in the management of diseases caused by multidrug‐resistant bacterial pathogens and represent the last‐line therapy for bacterial infections. Therefore, there is a demand for a rationale use of such ATBs based on optimization of the dosing strategy to minimize the risk of resistance and ensure the sustainable efficacy of the drug in real clinical practice. Therapeutic drug monitoring, as a measurement of drug concentration in the body fluids or tissues, results in the optimization of the patient´s medication and therapy outcome. This strategy is beneficial and could result in tailored therapy for different types of infection and the prolongation of the use and efficacy of ATBs in hospitals. This review paper provides an actual overview of approved antimicrobial peptides used in clinical practice and covers current trends in their analysis by convenient and advanced methodologies used for their identification and/or quantitation in biological matrices for therapeutic drug monitoring purposes. Special emphasis is given to the methods with perspective clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Critically ill patients with sepsis have a high incidence of vitamin D deficiency. Vitamin D promotes the synthesis of human cathelicidin antimicrobial peptide, a precursor of LL-37, which is a part of the innate immune system. This study investigated the effectiveness and safety of the early administration of high-dose enteral vitamin D3 in comparison with low-dose vitamin D3 in patients with sepsis requiring mechanical ventilation (MV). Methods: Eighty adult patients with sepsis requiring MV with known vitamin D deficiency were randomly assigned to receive either an enteral 50 000 IU (Group I) or 5000 IU (Group II) vitamin D supplementation. Clinical and laboratory parameters were evaluated at baseline and on days 4 and 7 between the study groups. The change in serum procalcitonin (PCT) levels on day 7 was the primary outcome, while the change in serum LL-37 levels on day 7, changes in sequential organ failure assessment (SOFA) score, and clinical pulmonary infection score on day 7, MV duration, and hospital length of stay (LOS) were the secondary outcomes. Results: The (day 7-day 0) change in serum PCT and LL-37 levels and SOFA score were significantly different in Group I (P =.010, P <.001, and P <.001, respectively). The SOFA score was significantly different on days 4 and 7 in Group I (P <.001 and P <.001, respectively). The incidence of early ventilator-associated pneumonia was significantly different between both treatment groups (P =.025). The hospital LOS was shorter in Group I (P <.001). No 25-hydroxyvitamin-D toxicity was observed in either group. Conclusions: Early enteral administration of high-dose vitamin D3 in critically ill patients with sepsis requiring MV along with standard treatment for sepsis decreased serum procalcitonin levels, increased serum LL-37 levels, and ameliorated illness severity scores. [ABSTRACT FROM AUTHOR]