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Many factors contribute to bacterial membrane stabilization, including steric effects between lipids, membrane spontaneous curvature, and the difference in the number of neighboring molecules. This forum provides an overview of the physicochemical properties associated with membrane curvature and how this parameter can be tuned to design more effective antimicrobial peptides. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a common bacterium on the skin and in the nose that sometimes causes severe illness. Bacteriocins, antimicrobial peptides, or proteins produced by bacteria are candidates for the treatment of S. aureus infection. In this study, we found that a clinical Staphylococcus epidermidis strain, KSE112, produced the lantibiotic Pep5, which showed anti-S. aureus activity. The complete nucleotide sequence of the Pep5-encoding plasmid was determined. Several S. aureus two-component regulatory systems (TCSs) are known to be involved in bacteriocin susceptibility. Therefore, susceptibility tests were performed using TCS-inactivated S. aureus mutants to determine which TCS is responsible for Pep5 susceptibility; the ΔgraRS mutant exhibited increased susceptibility to Pep5, while the ΔsrrAB mutant exhibited decreased susceptibility. GraRS is known to regulate dltABCD and mprF in concert with vraFG, and Pep5 susceptibility was significantly increased in the ΔdltABCD, ΔmprF, and ΔvraFG mutants. Regarding the ΔsrrAB mutant, cross-resistance to aminoglycosides was observed. As aminoglycoside activity is known to be affected by aerobic respiration, we focused on qoxABCD and cydAB, which are quinol oxidase genes that are necessary for aerobic respiration and have downregulated the expression in the ΔsrrAB mutant. We constructed ΔqoxABCD and ΔcydAB mutants and found that qoxABCD inactivation decreased susceptibility to Pep5 and aminoglycosides. These results indicate that reduced aerobic respiration due to the reduced qoxABCD expression in the ΔsrrAB mutant decreased Pep5 activity. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis and Fusobacterium nucleatum are known to contribute to a variety of tumorigenic pathways linked to the progression of oral squamous cell carcinoma (OSCC). The growing global incidence of antibiotic resistance highlights the critical need to consider the use of antimicrobial peptides (AMPs) as a viable alternative to conventional antibiotics. The current study comprehensively tested Lactobacillus sp.−derived AMPs against bacterially exacerbated OSCC. A total of 52 AMPs were obtained from various databases, and an in silico analysis determined their potent antibacterial and anticancer characteristics after a rigorous screening and pruning approach. Twelve AMPs were tested for 3D structural alignment prediction and validation, with the GH12 synthetic AMP serving as a control. These candidate peptides were thoroughly screened against six important virulence proteins of P. gingivalis and four of F. nucleatum, with the lowest energy score of the docked complexes measuring binding affinity and interactions with active residues being chosen. plpl_18 was determined as the most efficient new AMP that interacted with the virulence protein RagB of P. gingivalis and Fap2 of F. nucleatum with docking scores of −238.24 and −254.27 kcal/mol, respectively. This AMP plpl_18 was docked against selective target OSCC regulatory proteins such as cytokines, metallomatrix proteinase, MAPK, E‐cadherin, and JAK‐1 proteins. Among these proteins, it docked against matrix metalloproteinase‐9 with the highest negative docking scores of −7.5, −260.956, and −1361.9 kcal/mol using AutoDock Vina, HPEPDOCK, and ClusPro 2.0, respectively. Molecular dynamic simulation was used to perform extrapolated validation. These computational studies provide an essential foundation for anticipated laboratory and clinical investigations concerning the possibility of adapting therapeutic peptides based on probiotics to combat the proliferation of OSCC, which is accelerated by F. nucleatum and P. gingivalis. [ABSTRACT FROM AUTHOR]

Wasps have been neglected in toxinological studies, even with their diversity of species, when compared to other groups of venomous animals such as snakes, scorpions, and spiders. Solitary wasps, such as Pepsis decorata, are known for their mechanism of total or temporary paralysis of the host. In addition, their venoms are considered sources for studies of small peptides, bioactive peptides with neural and antimicrobial activities. In this work, some oligopeptides were analyzed by de novo sequencing identifying 39 oligopeptide sequences. Some sequences were similar to proctolin, a bradykinin‐potentiating peptide, and poneritoxin, one bradykinin‐related peptide. As proctolin‐like peptides were the major constituent in distinct experimental conditions, it was selected for further in silico studies in order to understand its possible importance as a constituent of wasp venom and whether these peptides could be of biotechnological importance. We investigate its binding mode comparing with proctolin and we further analyzed the importance of the tyrosine‐leucine‐glutamic acid (YLE) tripeptide‐motif conservation. This experimental, an in silico approach, increased the range of compounds identified in peptide analyses proving good characterization of little‐known peptidic compounds. [ABSTRACT FROM AUTHOR]

In the realm of therapeutic peptides, tremendous progress has been achieved in the last two decades. The building block of peptides that is, 'Amino Acid' has been modified by various chemical modifications such as side‐chain alteration in linear peptides, cyclization, back‐bone modification, pro‐drug moiety, conjugation with heterocycles, and natural products to make peptides a foremost candidate as a therapeutic drug. Since the advent of insulin in 1922, peptides have immensely affected the development of the pharmaceutical industry giving rise to the peptide‐based drug industry. In recent years, peptides having antimicrobial, antiviral, anti‐tumor, anti‐inflammatory, anti‐aging, and antioxidant properties have developed. Also, it has now entered as a potent candidate in the field of oncology and also become a valuable tool as a radiolabeled peptide for the detection of various diseases. Generally, peptides were extracted from natural sources in the olden days, but presently work is directed towards finding alternate and sustainable ways for developing synthetic peptides. The present review covers the discussion about the historic evaluation of peptides, available effective synthetic processes, current advancements, use of bioinformatic tools, computational strategies, and the methodology to overcome the barrier for making peptides the potent candidate for the future world. [ABSTRACT FROM AUTHOR]

Infected bone defect (IBD) is a great challenge in orthopedics, which involves in bone loss and infection. Here, a self-assembling hydrogel scaffold (named AMP-RAD/EXO), integrating antimicrobial peptides(AMPs), RADA16 and BMSCs exosomes with an innovative strategy, is developed and applied in IBD treatment for sustained antimicrobial ability, accelerating osteoblasts proliferation and promoting bone regeneration. AMPs present an excellent ability to inhibit infection, RADA16 is a self-assembling peptide hydrogel for AMPs delivery, and BMSCs exosomes can promote the bone regeneration. The prepared AMP-RAD/EXO exhibited a polyporous 3D structure for imbibition of BMSCs exosomes and migration of osteoblasts. In vitro studies indicate AMP-RAD/EXO can inhibit the growth of Staphylococcus aureus, accelerate the proliferation and migration of BMSCs. More importantly, in vivo results also prove that AMP-RAD/EXO exhibit an excellent effect on IBD treatment. Thus, the prepared AMP-RAD/EXO provides a multifunctional scaffold concept for bone tissue engineering technology. [ABSTRACT FROM AUTHOR]

Background: Global public health is seriously threatened by the escalating issue of antimicrobial resistance (AMR). Antimicrobial peptides (AMPs), pivotal components of the innate immune system, have emerged as a potent solution to AMR due to their therapeutic potential. Employing computational methodologies for the prompt recognition of these antimicrobial peptides indeed unlocks fresh perspectives, thereby potentially revolutionizing antimicrobial drug development. Methods: In this study, we have developed a model named as deepAMPNet. This model, which leverages graph neural networks, excels at the swift identification of AMPs. It employs structures of antimicrobial peptides predicted by AlphaFold2, encodes residue-level features through a bi-directional long short-term memory (Bi-LSTM) protein language model, and constructs adjacency matrices anchored on amino acids' contact maps. Results: In a comparative study with other state-of-the-art AMP predictors on two external independent test datasets, deepAMPNet outperformed in accuracy. Furthermore, in terms of commonly accepted evaluation matrices such as AUC, Mcc, sensitivity, and specificity, deepAMPNet achieved the highest or highly comparable performances against other predictors. Conclusion: deepAMPNet interweaves both structural and sequence information of AMPs, stands as a high-performance identification model that propels the evolution and design in antimicrobial peptide pharmaceuticals. The data and code utilized in this study can be accessed at https://github.com/Iseeu233/deepAMPNet. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 is a new, widespread virus pandemic that started in late 2019. It targets the respiratory system, especially the lungs and airways, through the spread of infected water droplets being inhaled through person-to-person transmission. Current treatments include oral antiviral pills like Paxlovid and mRNA vaccines, but these treatments have limitations in not reducing the occurrence of a common side effect of COVID-19. In this paper, we study the correlation of how SARS-CoV-2 (COVID-19) in intubated patients on ventilators can develop subglottic stenosis (SGS) during such treatments. When SARSCoV-2 patients are treated with these devices, their tubes can injure and possibly scar the airway epithelium, resulting in excessive scar tissue growth that blocks the airway, which is SGS. SGS arises when an injury in the airway stimulates rapid scar tissue growth to the point where the airway becomes too narrow and obstructed for breathing. It can also lead to the entire airway collapsing in severe cases. Even then, many current treatments for SGS, such as laryngotracheal reconstruction (LTR) and partial cricotracheal resection (CTR) surgeries, make the condition of the patients worse, especially with long-COVID patients with comorbidities potentially having a collapsed trachea. Thus, it is essential to find novel treatments to lower the risk of SGS in patients with such severe cases of COVID-19. Therefore, in this work, we discuss novel therapies to treat SGS cases that have been occurring from incidences of COVID-19 as a way to improve patient outcomes and save lives. [ABSTRACT FROM AUTHOR]

The oral cavity, a unique ecosystem harboring diverse microorganisms, maintains health through a balanced microflora. Disruption may lead to disease, emphasizing the protective role of gingival epithelial cells (GECs) in preventing harm from pathogenic oral microbes. Shifting GECs' response from proinflammatory to antimicrobial could be a novel strategy for periodontitis. Photobiomodulation therapy (PBMT), a nonpharmacologic host modulatory approach, is considered an alternative to drugs. While the host cell response induced by a single type of pathogen-associated molecular patterns (PAMPs) was widely studied, this model does not address the cellular response to intact microbes that exhibit multiple PAMPs that might modulate the response. Inspired by this, we developed an in vitro model that simulates direct interactions between host cells and intact pathogens and evaluated the effect of PBMT on the response of human gingival keratinocytes (HGKs) to challenge viable oral microbes at both the cellular and molecular levels. Our data demonstrated that LED pretreatment on microbially challenged HGKs with specific continuous wavelengths (red: 615 nm; near-infrared: 880 nm) induced the production of various antimicrobial peptides, enhanced cell viability and proliferation, promoted reactive oxygen species scavenging, and down-modulated proinflammatory activity. The data also suggest a potential explanation regarding the superior efficacy of near-infrared light treatment compared with red light in enhancing antimicrobial activity and reducing cellular inflammation of HGKs. Taken together, the findings suggest that PBMT enhances the overall barrier function of gingival epithelium while minimizing inflammation-mediated breakdown of the underlying structures. [ABSTRACT FROM AUTHOR]

In the present study, we identified and characterized two defensin‐like peptides in an antifungal fraction obtained from Capsicum chinense pepper fruits and inhibited the growth of Colletotrichum scovillei, which causes anthracnose. AMPs were extracted from the pericarp of C. chinense peppers and subjected to ion exchange, molecular exclusion, and reversed‐phase in a high‐performance liquid chromatography system. We investigated the endogenous increase in reactive oxygen species (ROS), the loss of mitochondrial functioning, and the ultrastructure of hyphae. The peptides obtained from the G3 fraction through molecular exclusion chromatography were subsequently fractionated using reverse‐phase chromatography, resulting in the isolation of fractions F1, F2, F3, F4, and F5. The F1‐Fraction suppressed C. scovillei growth by 90, 70.4, and 44% at 100, 50, and 25 μg mL−1, respectively. At 24 h, the IC50 and minimum inhibitory concentration were 21.5 μg mL−1 and 200 μg mL−1, respectively. We found an increase in ROS, which may have resulted in an oxidative burst, loss of mitochondrial functioning, and cytoplasm retraction, as well as an increase in autophagic vacuoles. MS/MS analysis of the F1‐Fraction indicated the presence of two defensin‐like proteins, and we were able to identify the expression of three defensin sequences in our C. chinense fruit extract. The F1‐Fraction was also found to inhibit the activity of insect α‐amylases. In summary, the F1‐Fraction of C. chinense exhibits antifungal activity against a major pepper pathogen that causes anthracnose. These defensin‐like compounds are promising prospects for further research into antifungal and insecticide biotechnology applications. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a critical public health concern, necessitating the exploration of alternative treatments. While antimicrobial peptides (AMPs) show promise, assessing their toxicity using traditional wet lab methods is both time‐consuming and costly. We introduce tAMPer, a novel multi‐modal deep learning model designed to predict peptide toxicity by integrating the underlying amino acid sequence composition and the three‐dimensional structure of peptides. tAMPer adopts a graph‐based representation for peptides, encoding ColabFold‐predicted structures, where nodes represent amino acids and edges represent spatial interactions. Structural features are extracted using graph neural networks, and recurrent neural networks capture sequential dependencies. tAMPer's performance was assessed on a publicly available protein toxicity benchmark and an AMP hemolysis data we generated. On the latter, tAMPer achieves an F1‐score of 68.7%, outperforming the second‐best method by 23.4%. On the protein benchmark, tAMPer exhibited an improvement of over 3.0% in the F1‐score compared to current state‐of‐the‐art methods. We anticipate tAMPer to accelerate AMP discovery and development by reducing the reliance on laborious toxicity screening experiments. [ABSTRACT FROM AUTHOR]

Capitellacin (1) is a 20-residue antimicrobial β-hairpin, produced by the marine polychaeta (segmented worms) Capitella teletai. Since its discovery in 2020, only very limited studies have been undertaken to understand capitellacin's structure–activity relationship (SAR). Using fast-flow Fmoc-SPPS, a focused library of capitellacin analogues was prepared to systematically study the influence of the two disulphide bridges on its structure and activity, and their replacement with a vinyl sulphide as a potential bioisostere. Upon studying the resulting peptides' antimicrobial activity and secondary structure, the most terminal disulphide emerged as the most critical element for maintaining both bioactivity and the secondary structure, properties which were demonstrated to be closely interlinked. The removal of the innermost disulphide bridge or disulphide replacement with a vinyl sulphide emerged as strategies with which to tune the activity spectrum, producing selectivity towards E. coli. Additionally, an enantiomeric d-capitellacin analogue revealed mechanistic insights, suggesting that chirality may be an inherent property of capitellacin's bacterial membrane target, or that a hitherto unknown secondary mechanism of action may exist. Additionally, we propose the Alloc protecting group as a more appropriate alternative to the common Dde group during fast-flow Fmoc-SPPS, in particular for short-chain diamino acids. [ABSTRACT FROM AUTHOR]

The treatment of infectious diseases typically includes the administration of anti-infectives; however, the increasing rates of antimicrobial resistance (AMR) have led to attempts to develop other modalities, such as antimicrobial peptides, nanotechnology, bacteriophages, and natural products. Natural products offer a viable alternative due to their potential affordability, ease of access, and diverse biological activities. Flavonoids, a class of natural polyphenols, demonstrate broad anti-infective properties against viruses, bacteria, fungi, and parasites. Their mechanisms of action include disruption of microbial membranes, inhibition of nucleic acid synthesis, and interference with bacterial enzymes. This review explores the potential of natural compounds, such as flavonoids, as an alternative therapeutic approach to combat infectious diseases. Moreover, it discusses some commonly used natural products, such as cranberry and D-mannose, to manage urinary tract infections (UTIs). Cranberry products and D-mannose both, yet differently, inhibit the adhesion of uropathogenic bacteria to the urothelium, thus reducing the likelihood of UTI occurrence. Some studies, with methodological limitations and small patient samples, provide some encouraging results suggesting the use of these substances in the prevention of recurrent UTIs. While further research is needed to determine optimal dosages, bioavailability, and potential side effects, natural compounds hold promise as a complementary or alternative therapeutic strategy in the fight against infectious diseases. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the impact of an antimicrobial peptide, BiF2_5K7K, on semen quality and bacterial contamination in boar semen doses used for artificial insemination. A key factor affecting semen quality and farm production is bacterial contamination in semen doses. Using antibiotics in a semen extender seems to be the best solution for minimizing bacterial growth during semen preservation. However, concern regarding antibiotic-resistant microorganisms has grown globally. As a result, antimicrobial peptides have emerged as interesting alternative antimicrobial agents to replace the current antibiotics used in semen extenders. BiF2_5K7K is an antimicrobial peptide that can inhibit Gram-negative and Gram-positive bacteria isolated from boar semen and sow vaginal discharge. In this study, ten fresh boar semen samples were collected and diluted with one of two types of semen extender: with (positive control) or without (negative control) an antibiotic (i.e., gentamicin). The semen extender without an antibiotic contained antimicrobial peptide BiF2_5K7K at different concentrations (15.625, 31.25, 62.5, and 125 µg/mL). The samples were stored at 18 °C until use. Semen quality parameters were assessed on days 0, 1, 3, and 5, and the total bacterial count was also evaluated at 0, 24, 36, 48, and 72 h after storage. A fertility test on a pig farm was also performed via sow insemination with a commercial extender plus BiF2_5K7K at a concentration of 31.25 µg/mL. No significant difference was found in terms of semen quality on days 0 or 1. On days 3 and 5, the total motility, progressive motility, and viability remained normal in the 15.625 and 31.25 µg/mL groups. However, the sperm parameters decreased starting on day 3 for the 125 µg/mL group and on day 5 for the 62.5 µg/mL group. For total bacterial count at 0, 24, 36, 48, and 72 h, the lowest bacterial count was found in the positive control group, and the highest bacterial count was found in the negative control group compared with the other groups. Comparing antimicrobial peptide groups from 0 to 48 h, the lowest bacterial count was found in the 125 µg/mL group, and the highest bacterial count was found in the 15.625 µg/mL group. For the fertility test, artificial insemination was conducted by using a commercial extender plus BiF2_5K7K at a concentration of 31.25 µg/mL. The results showed a superior pregnancy rate, farrowing rate, and total number of piglets born compared with artificial insemination conducted using a commercial extender plus antibiotic. In conclusion, BiF2_5K7K can inhibit bacterial growth in extended boar semen for 24 h, and thereafter, the bacterial count slightly increases. However, the increase in the number of bacterial counts from days 0 to 3 had no negative effect on sperm quality in the positive control, 15.625, or 31.25 µg/mL groups. This indicates that BiF2_5K7K might be an antimicrobial peptide candidate with potential for use as an alternative antimicrobial agent to replace the conventional antibiotic used in boar semen extenders. [ABSTRACT FROM AUTHOR]

The overuse of traditional antibiotics has resulted in bacterial resistance and seriously compromised the therapeutic efficacy of traditional antibiotics, making the exploration of new antimicrobials particularly important. Several studies have shown that bioactive peptides have become an important source of new antimicrobial drugs due to their broad-spectrum antibacterial action and lack of susceptibility to resistance. In this study, a novel bioactive peptide Nigrosin-6VL was characterised from the skin secretion of the golden cross band frog, Odorrana andersonii, by using the 'shotgun' cloning strategy. Modifications on the Rana Box of Nigrosin-6VL revealed its critical role in antimicrobial functions. The peptide analogue, 2170-2R, designed to preserve the Rana Box structure while enhancing cationicity, exhibited improved therapeutic efficacy, particularly against Gram-negative bacteria, with a therapeutic value of 45.27. Synergistic studies demonstrated that 2170-2R inherits the synergistic antimicrobial activities of the parent peptides and effectively enhances the antimicrobial capacity of cefepime and gentamicin against both planktonic cells and biofilms. Specifically, 2170-2R can synergise effectively with cefepime and gentamicin against different strains of P. aeruginosa biofilms. Consequently, 2170-2R holds promise as a potent antimicrobial agent developed to combat infections induced by Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) function to extensively suppress various problematic factors and are considered a new alternative for improving livestock health and enhancing immunomodulation. In this study, we explored whether AMP regulation has positive influences on Ochratoxin A (OTA) exposure using a porcine intestinal epithelial cell line (IPEC-J2 cells). We constructed a beta-defensin 1 (DEFB1) expression vector and used it to transfection IPEC-J2 cells to construct AMP overexpression cell lines. The results showed that OTA induced cytotoxicity, decreased cell migration, and increased inflammatory markers mRNA in IPEC-J2 cells. In DEFB1 overexpressing cell lines, OTA-induced reduced cell migration and increased inflammatory markers mRNA were alleviated. Additionally, a natural product capable of inducing DEFB1 expression, which was selected through high-throughput screening, showed significant alleviation of cytotoxicity, cell migration, and inflammatory markers compared to OTA-treated IPEC-J2 cells. Our finding provides novel insights and clues for the porcine industry, which is affected by OTA exposure. [ABSTRACT FROM AUTHOR]

For centuries, humans have used mushrooms as both food and pro-health supplements. Mushrooms, especially those related to the functions of the human immune system, are rich in dietary fiber, minerals, essential amino acids, and various bioactive compounds and have significant health-promoting properties. Immunoregulatory compounds in mushrooms include lectins, terpenes, terpenoids, polysaccharides, and fungal immunomodulatory proteins (FIPs). The distribution of these compounds varies from one species of mushroom to another, and their immunomodulatory activities depend on the core structures and chemical modifications in the composition of the fractions. In this review, we describe active compounds from medical mushrooms. We summarize potential mechanisms for their in vitro and in vivo activities and detail approaches used in developing and applying bioactive compounds from mushrooms. Finally, we discuss applications of fungal peptides and highlight areas that require improvement before the widespread use of those compounds as therapeutic agents and explore the status of clinical studies on the immunomodulatory activities of mushrooms and their products, as well as the prospect of clinical application of AMPs as 'drug-like' compounds with great potential for treatment of non-healing chronic wounds and multiresistant infections. [ABSTRACT FROM AUTHOR]

The marine environment is the largest ecological habitat on Earth, albeit one of the least explored, particularly in terms of its microbial inhabitants. The marine fish gut is host to a diverse microbial community from which diverse bioactive molecules can be sourced. Due to the unique environmental pressures these microbial communities experience, the bioactive molecules they produce often evolve unique adaptations that give them diverse structures and activities, differentiating them from terrestrial homologues. Of particular interest, due to their structural and functional diversity, are the ribosomally-synthesized antimicrobial peptides (bacteriocins). With increasing pressure from emerging antibiotic-resistant disease and industrial demand for novel therapeutics, the marine fish gut microbiome represents a relatively untapped resource of novel bacteriocins that could prove beneficial to human health and aquaculture. This review presents an overview of the marine fish gut microbiome and explores its potential as a source of bacteriocins for human health with considerations for applications and future research in this area. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) poses a serious global health concern, resulting in a significant number of deaths annually due to infections that are resistant to treatment. Amidst this crisis, antimicrobial peptides (AMPs) have emerged as promising alternatives to conventional antibiotics (ATBs). These cationic peptides, naturally produced by all kingdoms of life, play a crucial role in the innate immune system of multicellular organisms and in bacterial interspecies competition by exhibiting broad-spectrum activity against bacteria, fungi, viruses, and parasites. AMPs target bacterial pathogens through multiple mechanisms, most importantly by disrupting their membranes, leading to cell lysis. However, bacterial resistance to host AMPs has emerged due to a slow co-evolutionary process between microorganisms and their hosts. Alarmingly, the development of resistance to last-resort AMPs in the treatment of MDR infections, such as colistin, is attributed to the misuse of this peptide and the high rate of horizontal genetic transfer of the corresponding resistance genes. AMP-resistant bacteria employ diverse mechanisms, including but not limited to proteolytic degradation, extracellular trapping and inactivation, active efflux, as well as complex modifications in bacterial cell wall and membrane structures. This review comprehensively examines all constitutive and inducible molecular resistance mechanisms to AMPs supported by experimental evidence described to date in bacterial pathogens. We also explore the specificity of these mechanisms toward structurally diverse AMPs to broaden and enhance their potential in developing and applying them as therapeutics for MDR bacteria. Additionally, we provide insights into the significance of AMP resistance within the context of host–pathogen interactions. [ABSTRACT FROM AUTHOR]

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Abstract The current reports on phytopathogens multidrug resistance have become a significant issue for plant health and global food security. Antimicrobial peptides (AMPs) have recently gained generous attention as potential alternatives to prevent plant disease resistance because of their potent, multifarious antimicrobial activity. AMPs are low-weight protein molecules. Living organisms secrete a wide range of AMPs, with some synthesised by canonical gene expression, known as ribosomal AMPs, and non-ribosomal AMPs, synthesised by modular enzyme-generating systems. Plants produce an array of AMPs, yet they are still unknown to many infection processes of causal agents. Plant-derived AMPs have a wide range of structures and functions, and they induce an innate immune system in plants. The biologically active AMPs in plants mainly depend on direct and indirect interactions with membrane lipids. Transgenic plants have expressed several AMPs, the basis for the model of new synthetic analogues, to provide support against diseases. These peptides have shown significant ability to manage plant diseases and can provide an eco-friendly alternative to hazardous conventional methods. Here, we have a comprehensive study on AMPs to identify their role in plant pathogen stress suppression activities and their mode of action. This would surely facilitate a bottomless insight into AMPs' mode of action against pathogen infections. An improved understanding of the mechanism will facilitate the development of the next generation of antimicrobial peptides, potentially employing a multitargeted approach.

Abstract Background Cathelicidins are vital antimicrobial peptides expressed in diverse vertebrates, crucial for immunity. Despite being a new field, amphibian cathelicidin research holds promise. Results We isolated the cDNA sequence of the cathelicidin (Ll-CATH) gene from the liver transcriptome of the Chong’an Moustache Toad (Leptobrachium liui). We confirmed the authenticity of the cDNA sequence by rapid amplification of cDNA ends and reverse transcription PCR, and obtained the Ll-CATH amino acid sequence using the Open Reading Frame Finder, an online bioinformatics tool. Its translated protein contained a cathelin domain, signal peptide, and mature peptide, confirmed by amino acid sequence. The comparative analysis showed that the mature peptides were variable between the amphibian species, while the cathelin domain was conserved. The concentration of Ll-CATH protein and the expression of its gene varied in the tissues, with the spleen showing the highest levels. The expression levels of Ll-CATH in different tissues of toads was significantly increased post infection with Aeromonas hydrophila. Chemically synthesized Ll-CATH effectively combated Proteus mirabilis, Staphylococcus epidermidis, Vibrio harveyi, V. parahaemolyticus, and V. vulnificus; disrupted the membrane of V. harveyi, hydrolyzed its DNA. Ll-CATH induced chemotaxis and modulated the expression of pro-inflammatory cytokine genes in RAW264.7 macrophages. Conclusions This study unveiled the antibacterial and immunomodulatory potential of amphibian cathelicidin, implying its efficacy against infections. Ll-CATH characterization expands our knowledge, emphasizing its in a bacterial infection therapy.

Due to antimicrobial activity, nanoparticles (NPs) in combination with antimicrobial peptides (AMPs) can be used to kill drug-resistant (MDR) pathogens. Nanosilver (AgNPs) has broad-spectrum and efficient antimicrobial properties, multiple bacterial inactivation mechanisms, and the ability to fine-tune the conjugation on the surface of antimicrobial peptide-conjugated silver nanoparticles (AMP-AgNPs), which results in higher biosafety of AMP-AgNPs. The review summarized the latest research progress of AMP-AgNPs conjugates and discussed the synthesis method, antibacterial activity, mechanism of action, hemolytic toxicity of AMP-AgNPs conjugates, as well as their applications in medical and food fields. The future development direction of AMP-AgNPs conjugates was also prospected.

New drugs for the treatment of bacterial vaginosis (BV) are yet to be developed due to concerns that they may contribute to the increase in antibiotic resistance in BV. Antimicrobial peptides (AMPs) are one of the most promising options for next-generation antibiotics. In this study, we investigated the bacteriostatic activity of the AMPs Pexiganan, plectasin, melittin, and cathelicidin-DM against Gram-negative and Gram-positive bacteria both in vitro and in a mouse model of BV infection. The results showed that Pexiganan, melittin, and cathelicidin-DM had significant antibacterial activity against both Gram-negative and Gram-positive bacteria. AMPs have great potential for clinical application in the treatment of vaginitis, and this study provides an experimental basis for their use in the active immunoprophylaxis of BV.

Abstract Background This systematic review aims to review and assess the importance and relationship between host defence antimicrobial peptides with type 2 diabetes mellitus (T2DM) complications and the correlation of their expression with hyperglycaemic status. Main body The systematic search included three electronic databases (PMC, PubMed, and Google Scholar) that were searched from July to November 2023. After identifying and screening the research articles, eleven studies fulfilled the selection criteria and were included (six case–control and five cross-sectional studies). The Newcastle Ottawa Scale assessed the selected studies’ quality. Most studies indicated a correlation between certain types of AMPs and diabetic complications. Conclusion Hyperglycaemia in type 2 diabetes mellitus (T2DM) affects the expression of certain types of antimicrobial peptides (AMPs) which have a dual function (antibacterial and modulation of immune response) that may enhance inflammation which may correlate with the development of long-term complications, increased susceptibility to bacterial infection, and impaired wound healing.

Successful treatment of endodontic and periapical diseases requires the elimination of bacteria and microbial biofilms from root canals. Currently, the most preferred irrigation method involves the delivery of sodium hypochlorite via the combination of a syringe and ultrasonic activation. Calcium hydroxide is the main choice for intracanal medicament between endodontic appointments and treatment. However, conventional chemical disinfection of root canals is controversial due to drug permeability and drug resistance. New small biomolecule formulations with high penetrability and bioremediatory capacity, including antimicrobial peptides such as M33D and LL-37, antisense RNA ASwalR/ASvicR and nanoparticles such as silver nanoparticles, mesoporous calcium-silicate nanoparticles and chitosan nanoparticles, have effective antibacterial and antibiofilm properties for use in root canal systems and dentinal tubules, thereby promoting the healing of apical lesions. However, the in vivo drug stability, biosafety, and clinical efficacy of small biomolecule formulations need further investigation. Future research will still focus on the improvement and combination of traditional drugs, as new small molecule formulations and ideal disinfectant drugs need to be developed. In the present paper, we reviewed the development of new antibacterial agents and application of small biomolecule formulations for chemical disinfection of infected root canals.

The mammalian gut secretes a family of multifunctional peptides that affect appetite, intestinal secretions, and motility whereas others regulate the microbiota. We have found that peptide YY (PYY1-36), but not endocrine PYY3-36, acts as an antimicrobial peptide (AMP) expressed by gut epithelial paneth cells (PC). PC-PYY is packaged into secretory granules and is secreted into and retained by surface mucus, which optimizes PC-PYY activity. Although PC-PYY shows some antibacterial activity, it displays selective antifungal activity against virulent Candida albicans hyphae-but not the yeast form. PC-PYY is a cationic molecule that interacts with the anionic surfaces of fungal hyphae to cause membrane disruption and transcriptional reprogramming that selects for the yeast phenotype. Hence, PC-PYY is an antifungal AMP that contributes to the maintenance of gut fungal commensalism.

Antimicrobial peptides (AMPs) are increasingly recognized as potent therapeutic agents, with their selective affinity for pathological membranes, low toxicity profile, and minimal resistance development making them particularly attractive in the pharmaceutical landscape. This study offers a comprehensive analysis of the interaction between specific AMPs, including magainin-2, pleurocidin, CM15, LL37, and clavanin, with lipid bilayer models of very different compositions that have been ordinarily used as biological membrane models of healthy mammal, cancerous, and bacterial cells. Employing unbiased molecular dynamics simulations and metadynamics techniques, we have deciphered the intricate mechanisms by which these peptides recognize pathogenic and pathologic lipid patterns and integrate into lipid assemblies. Our findings reveal that the transverse component of the peptide's hydrophobic dipole moment is critical for membrane interaction, decisively influencing the molecule's orientation and expected therapeutic efficacy. Our approach also provides insight on the kinetic and dynamic dependence on the peptide orientation in the axial and azimuthal angles when coming close to the membrane. The aim is to establish a robust framework for the rational design of peptide-based, membrane-targeted therapies, as well as effective quantitative descriptors that can facilitate the automated design of novel AMPs for these therapies using machine learning methods.

Host defense or antimicrobial peptides (AMPs) are promising candidates for protecting host against microbial pathogens for example bacteria, virus, fungi, yeast. Defensins are the type of AMPs that act as potential therapeutic drug agent and perform vital role in various biological process. Conventional Experiments to identify defensin peptides (DPs) are time consuming and expensive. Thus, the shortcomings of wet lab experiments are leveraged by computational methods to accurately predict the functional types of DPs. In this paper, we aim to propose a novel multi-class ensemble-based prediction model called StackDPPred for identifying the properties of DPs. The peptide sequences are encoded using split amino acid composition (SAAC), segmented position specific scoring matrix (SegPSSM), histogram of oriented gradients-based PSSM (HOGPSSM) and feature extraction based graphical and statistical (FEGS) descriptors. Next, principal component analysis (PCA) is used to select the best subset of attributes. After that, the optimized features are fed into single machine learning and stacking-based ensemble classifiers. Furthermore, the ablation study demonstrates the robustness and efficacy of the stacking approach using reduced features for predicting DPs and their families. The proposed StackDPPred method improves the overall accuracy by 13.41% and 7.62% compared to existing DPs predictors iDPF-PseRAAC and iDEF-PseRAAC, respectively on validation test. Additionally, we applied the local interpretable model-agnostic explanations (LIME) algorithm to understand the contribution of selected features to the overall prediction. We believe, StackDPPred could serve as a valuable tool accelerating the screening of large-scale DPs and peptide-based drug discovery process. • We developed StackDPPred, a multiclass prediction model for defensin peptides with optimized set of features. • We encoded the sequences with four types of novel features by FEGS, SegPSSM, HOGPSSMm and SAAC descriptor. • We optimized the hybrid features by PCA and improved the prediction performance of the StackDPPred model. • The proposed StackDPPred model outperformed existing models for anti-defensin peptide prediction. [ABSTRACT FROM AUTHOR]

The intestine is the principal digestive organ which is generally divided into three segments as the proximal intestine (PI), the mid intestine (MI), and the distal intestine (DI) in fish. In this study, the role of dietary vitamin D3 (VD3) in regulating the function and health of different intestinal segments was evaluated in grass carp (Ctenopharyngodon idella) fingerlings through the supplementation with the increasing levels of dietary VD3 (0, 500, 1000, 1500, 2000, and 2500 IU/kg). The results showed that VD3 supplementation (1000–2000 IU/kg) significantly enhanced the fish growth performance, and the correlation analysis suggested that this effect was positively correlated with intestinal somatic index (ISI) and intestinal length index (ILI) of MI and DI except PI. In support of this finding, dietary VD3 enhanced the activities of digestive and brush border enzymes in the fish mainly in MI and DI rather than PI. Furthermore, the intestinal microbiota analysis revealed that VD3 increased the abundance of intestinal flora at the genus level rather than the phylum level. Meanwhile, hematoxylin and eosin staining presented that VD3 supplementation reduced epithelial goblet cell hyperplasia and lamina propria edema compared with the VD3 deficiency group in the MI and DI. Further studies showed that feeding VD3 decreased malondialdehyde levels but increased total antioxidant capacity, glutathione levels, and total superoxidase activity in MI or DI but not PI, suggesting the antioxidant potential of VD3 in two intestinal segments. Moreover, in MI and DI but not PI, dietary VD3 suppressed pro-inflammatory cytokine (il1 β and tnf α ) but enhanced antimicrobial peptide (hepcidin and βdefensin) mRNA levels and increased the activities of immune-related enzymes (lysozyme and acid phosphatase), highlighting the ability to improve fish immunity. Corresponding to these effects, dietary VD3 was able to mediate NF-E2-related factor 2 (Nrf2) and NF-κB pathways in MI and DI. Finally, quadratic regression models based on weight gain (PWG), feed efficiency (PE), ISI, and ILI suggested that the appropriate VD3 requirements for grass carp fingerlings were 1233.70–1387.11 IU/kg. Taken together, our findings strengthened the potential of dietary VD3 in managing the functions and health of particular intestinal segments and provided valuable reference data for VD3 requirements of fingerling fish. [ABSTRACT FROM AUTHOR]

Abstract Broad‐spectrum antibacterial drugs often lack specificity, leading to indiscriminate bactericidal activity, which can disrupt the normal microbial balance of the host flora and cause unnecessary cytotoxicity during systemic administration. In this study, we constructed a specifically targeted antimicrobial peptide against Staphylococcus aureus by introducing a phage‐displayed peptide onto a broad‐spectrum antimicrobial peptide and explored its structure–function relationship through one‐factor modification. SFK2 obtained by screening based on the selectivity index and the targeting index showed specific killing ability against S. aureus. Moreover, SFK2 showed excellent biocompatibility in mice and piglet, and demonstrated significant therapeutic efficacy against S. aureus infection. In conclusion, our screening of phage‐derived heptapeptides effectively enhances the specific bactericidal ability of the antimicrobial peptides against S. aureus, providing a theoretical basis for developing targeted antimicrobial peptides.

Abstract Antimicrobial peptides (AMPs) have sparked significant interest as potential anti-cancer agents, thereby becoming a focal point in pursuing novel cancer-fighting strategies. These peptides possess distinctive properties, underscoring the importance of developing more potent and selectively targeted versions with diverse mechanisms of action against human cancer cells. Such advancements would offer notable advantages compared to existing cancer therapies. This research aimed to examine the toxicity and selectivity of the nrCap18 peptide in both cancer and normal cell lines. Furthermore, the rate of cellular death was assessed using apoptosis and acridine orange/ethidium bromide (AO/EB) double staining at three distinct incubation times. Additionally, the impact of this peptide on the cancer cell cycle and migration was evaluated, and ultimately, the expression of cyclin-dependent kinase 4/6 (CDK4/6) genes was investigated. The results obtained from the study demonstrated significant toxicity and selectivity in cancer cells compared to normal cells. Moreover, a strong progressive increase in cell death was observed over time. Furthermore, the peptide exhibited the ability to halt the progression of cancer cells in the G1 phase of the cell cycle and impede their migration by suppressing the expression of CDK4/6 genes.

Dawei Ren,1 Yan Zhang,1 Bo Du,1 Lina Wang,2 Meiheng Gong,1 Wei Zhu1 1Department of Otorhinolaryngology, the First Hospital of Jilin University, Changchun, People’s Republic of China; 2Department of Pediatric Respiration, the First Hospital of Jilin University, Changchun, People’s Republic of ChinaCorrespondence: Wei Zhu, Email zhuwei@jlu.edu.cnBackground: Electrical stimulation (ES) can effectively promote skin wound healing; however, single-electrode-based ES strategies are difficult to cover the entire wound area, and the effectiveness of ES is often limited by the inconsistent mechanical properties of the electrode and wound tissue. The above factors may lead to ES treatment is not ideal.Methods: A multifunctional conductive hydrogel dressing containing methacrylated gelatin (GelMA), Ti3C2 and collagen binding antimicrobial peptides (V-Os) was developed to improve wound management. Ti3C2 was selected as the electrode component due to its excellent electrical conductivity, the modified antimicrobial peptide V-Os could replace traditional antibiotics to suppress bacterial infections, and GelMA hydrogel was used due to its clinical applicability in wound healing.Results: The results showed that this new hydrogel dressing (GelMA@Ti3C2/V-Os) not only has excellent electrical conductivity and biocompatibility but also has a durable and efficient bactericidal effect. The modified antimicrobial peptides V-Os used were able to bind more closely to GelMA hydrogel to exert long-lasting antibacterial effects. The results of cell experiment showed that the GelMA@Ti3C2/V-Os hydrogel dressing could enhance the effect of current stimulation and significantly improve the migration, proliferation and tissue repair related genes expression of fibroblasts. In vitro experiments results showed that under ES, GelMA@Ti3C2/V-Os hydrogel dressing could promote re-epithelialization, enhance angiogenesis, mediate immune response and prevent wound infection.Conclusion: This multifunctional nanocomposite hydrogel could provide new strategies for promoting infectious wound healing. Keywords: MXene, GelMA, electrical stimulation, antimicrobial peptides, wound healing

Abstract Background The world faces a major infectious disease challenge. Interest in the discovery, design, or development of antimicrobial peptides (AMPs) as an alternative approach for the treatment of bacterial infections has increased. Insects are a good source of AMPs which are the main effector molecules of their innate immune system. Black Soldier Fly Larvae (BSFL) are being developed for large-scale rearing for food sustainability, waste reduction and as sustainable animal and fish feed. Bioinformatic studies have suggested that BSFL have the largest number of AMPs identified in insects. However, most AMPs identified in BSF have not yet undergone antimicrobial evaluation but are promising leads to treat critical infections. Results Jg7197.t1, Jg7902.t1 and Jg7904.t1 were expressed into the haemolymph of larvae following infection with Salmonella enterica serovar Typhimurium and were predicted to be AMPs using the computational tool ampir. The genes encoding these proteins were within 2 distinct clusters in chromosome 1 of the BSF genome. Following removal of signal peptides, predicted structures of the mature proteins were superimposed, highlighting a high degree of structural conservation. The 3 AMPs share primary sequences with proteins that contain a Kunitz-binding domain; characterised for inhibitory action against proteases, and antimicrobial activities. An in vitro antimicrobial screen indicated that heterologously expressed SUMO-Jg7197.t1 and SUMO-Jg7902.t1 did not show activity against 12 bacterial strains. While recombinant SUMO-Jg7904.t1 had antimicrobial activity against a range of Gram-negative and Gram-positive bacteria, including the serious pathogen Pseudomonas aeruginosa. Conclusions We have cloned and purified putative AMPs from BSFL and performed initial in vitro experiments to evaluate their antimicrobial activity. In doing so, we have identified a putative novel defensin-like AMP, Jg7904.t1, encoded in a paralogous gene cluster, with antimicrobial activity against P. aeruginosa.

Abstract Objective To evaluate the antibacterial effectiveness of a combination of ε-poly-L-lysine (ε-PL), funme peptide (FP) as well as domiphen against oral pathogens, and assess the efficacy of a BOP® mouthwash supplemented with this combination in reducing halitosis and supragingival plaque in a clinical trial. Materials and methods The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the compound against Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were determined by the gradient dilution method. Subsequently, the CCK-8 assay was used to detect the toxicity of mouthwash on human gingival fibroblastst, and the effectiveness in reducing halitosis and supragingival plaque of the mouthwash supplemented with the combination was analyzed by a randomized, double-blind, parallel-controlled clinical trial. Results The combination exhibited significant inhibitory effects on tested oral pathogens with the MIC

Abstract Background Esculentin-1, initially discovered in the skin secretions of pool frogs (Pelophylax lessonae), has demonstrated broad-spectrum antimicrobial activity; however, its immunomodulatory properties have received little attention. Results In the present study, esculentin-1 cDNA was identified by analysing the skin transcriptome of the dark-spotted frog (Pelophylax nigromaculatus). Esculentin-1 from this species (esculentin-1PN) encompasses a signal peptide, an acidic spacer peptide, and a mature peptide. Sequence alignments with other amphibian esculentins-1 demonstrated conservation of the peptide, and phylogenetic tree analysis revealed its closest genetic affinity to esculentin-1P, derived from the Fukien gold-striped pond frog (Pelophylax fukienensis). Esculentin-1PN transcripts were observed in various tissues, with the skin exhibiting the highest mRNA levels. Synthetic esculentin-1PN demonstrated antibacterial activity against various pathogens, and esculentin-1PN exhibited bactericidal activity by disrupting cell membrane integrity and hydrolyzing genomic DNA. Esculentin-1PN did not stimulate chemotaxis in RAW264.7, a murine leukemic monocyte/macrophage cell line. However, it amplified the respiratory burst and augmented the pro-inflammatory cytokine gene (TNF-α and IL-1β) expression in RAW264.7 cells. Conclusions This novel finding highlights the immunomodulatory activity of esculentin-1PN on immune cells.