Search

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]

In this study, the interaction of antimicrobial peptide Maximin 3 (Max3) with three different lipid bilayer models was investigated to gain insight into its mechanism of action and membrane specificity. Bilayer perturbation assays using liposome calcein leakage dose–response curves revealed that Max3 is a selective membrane‐active peptide. Dynamic light scattering recordings suggest that the peptide incorporates into the liposomal structure without producing a detergent effect. Langmuir monolayer compression assays confirmed the membrane inserting capacity of the peptide. Attenuated total reflection‐Fourier transform infrared spectroscopy showed that the fingerprint signals of lipid phospholipid hydrophilic head groups and hydrophobic acyl chains are altered due to Max3‐membrane interaction. On the other hand, all‐atom molecular dynamics simulations (MDS) of the initial interaction with the membrane surface corroborated peptide‐membrane selectivity. Peptide transmembrane MDS shed light on how the peptide differentially modifies lipid bilayer properties. Molecular mechanics Poisson–Boltzmann surface area calculations revealed a specific electrostatic interaction fingerprint of the peptide for each membrane model with which they were tested. The data generated from the in silico approach could account for some of the differences observed experimentally in the activity and selectivity of Max3. [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]

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]

Background: Skin commensal bacteria (Staphylococcus epidermidis) can help defend against skin infections, and they are increasingly being recognized for their role in benefiting skin health. This study aims to demonstrate the activities that Myristica fragrans Houtt. seed extracts, crude extract (CE) and essential oil (EO), have in terms of promoting the growth of the skin commensal bacterium S. epidermidis and providing metabolites under culture conditions to disrupt the biofilm formation of the common pathogen Staphylococcus aureus. Methods: The culture supernatant obtained from a co-culture of S. epidermidis with M. fragrans Houtt. seed extracts in either CE or EO forms were analyzed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS), in silico investigations, and applied to assess the survival and biofilm formation of S. aureus. Results: The combination of commensal bacteria with M. fragrans Houtt. seed extract either CE or EO produced metabolic compounds such as short-chain fatty acids and antimicrobial peptides, contributing to the antimicrobial activity. This antimicrobial activity was related to downregulating key genes involved in bacterial adherence and biofilm development in S. aureus, including cna, agr, and fnbA. Conclusion: These findings suggest that using the culture supernatant of the commensal bacteria in combination with CE or EO may provide a potential approach to combat biofilm formation and control the bacterial proliferation of S. aureus. This may be a putative non-invasive therapeutic strategy for maintaining a healthy skin microbiota and preventing skin infections. [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: Salmonella, a foodborne pathogen, possesses a type I-E clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated (Cas) system. We investigated the system's role in regulating Salmonella virulence by deleting the CRISPR arrays and Cas operon. Results: Our study demonstrates invasion and proliferation defects of CRISPR-Cas knockout strains in intestinal epithelial cells and macrophages owing to the repression of invasion and virulence genes. However, proliferation defects were not observed in the Gp91phox−/− macrophages, suggesting the system's role in the pathogens' antioxidant defense. We deduced that the CRISPR-Cas system positively regulates H2O2 importer (OmpW), catalase (katG), peroxidase (ahpC), and superoxide dismutase (soda and sodCI), thereby protecting the cells from oxidative radicals. The knockout strains were attenuated in in-vivo infection models (Caenorhabditis elegans and BALB/c mice) due to hypersensitivity against antimicrobial peptides, complement proteins, and oxidative stress. The attenuation in virulence was attributed to the suppression of LPS modifying (pmr) genes, antioxidant genes, master regulators, and effectors of the SPI-1 (invasion) and SPI-2 (proliferation) islands in knockout strains. The regulation could be attributed to the partial complementarity of the CRISPR spacers with these genes. Conclusions: Overall, our study extends our understanding of the role of the CRISPR-Cas system in Salmonella pathogenesis and its virulence determinants. [ABSTRACT FROM AUTHOR]

Background: Chronic obstructive pulmonary disease (COPD) is a complex respiratory condition influenced by environmental and genetic factors. Using next-generation sequencing, we aimed to identify dysregulated genes and potential therapeutic targets for COPD. Methods: Peripheral blood leukocyte RNA profiles from COPD patients and healthy controls were analyzed using next-generation sequencing. Key genes involved in COPD pathogenesis were identified through protein–protein interaction network analysis. In vitro, bronchial epithelial cells treated with cigarette smoke extract (CSE) were used to study the effects on gene expression, cell viability, apoptosis, and ferroptosis. Additionally, Lipocalin 2 (LCN2) inhibition experiments were conducted to elucidate its role in COPD-related cellular processes. Results: Analysis of RNA profiles revealed consistent downregulation of 17 genes and upregulation of 21 genes across all COPD groups. Among these, Cathelicidin Antimicrobial Peptide(CAMP), Defensin Alpha 4(DEFA4), Neutrophil Elastase(ELANE), LCN2 and Lactotransferrin(LTF) were identified as potentially important players in COPD pathogenesis. Particularly, LCN2 exhibited a close association with COPD and was found to be involved in cellular processes. In vitro experiments demonstrated that CSE treatment significantly increased LCN2 expression in bronchial epithelial cells in a concentration-dependent manner. Moreover, CSE-induced apoptosis and ferroptosis were observed, along with alterations in cell viability, Glutathione content, Fe2 + accumulation, ROS: Reactive Oxygen Species and Malondialdehyde levels, Lactate Dehydrogenase(LDH) release and Glutathione Peroxidase 4(GPX4) expression. Inhibition of LCN2 expression partially reversed these effects, indicating the pivotal role of LCN2 in COPD-related cellular processes. Conclusion: Our study identified six candidate genes: CAMP, DEFA4, ELANE, LCN2, and LTF were upregulated, HSPA1B was downregulated. Notably, LCN2 emerges as a significant biomarker in COPD pathogenesis, exerting its effects by promoting apoptosis and ferroptosis in bronchial epithelial cells. [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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Cysteine-rich peptides play an important role in the plant defense system. The objective of this study was in silico searching for the genes encoding antimicrobial and signaling peptides in the genome of the tall wheatgrass Thinopyrumelongatum (Host) D.R. Dewey (2n = 14, EE), a wild cereal that is highly resistant to pathogens and abiotic stress. Bioinformatic analysis provided information for the identification in the tall wheatgrass genome of 154 novel genes coding for antimicrobial and signaling peptide precursors belonging to nine families. A number of cysteine-rich peptide genes were found to contain introns. The structure of peptide precursors and the location of the peptide genes on the wheatgrass chromosomes were determined. The highest similarity of the wheatgrass peptide sequences with homologous peptides from plants of the genera Triticum and Aegilops was demonstrated, supporting the cytogenetic data on the relatedness between genome E and genome D, as well as the genomes close to it. The data obtained contribute to the characterization of the molecular components of the Th. elongatum immune system and will serve as the basis for further studies of the mechanisms of resistance, as well as for the scientifically based practical use of this species as the resistance donor in wheat breeding. [ABSTRACT FROM AUTHOR]

The document "Microalgae Biotechnology: Methods and Applications" discusses the potential of microalgae as sustainable chassis for biotechnology, emphasizing their ability to produce valuable compounds and remediate pollutants. Advances in genetic tools and techniques, such as CRISPR/Cas9, are crucial for enhancing microalgal biotechnology. The document also highlights the use of synthetic biology to produce antimicrobial peptides in microalgae, offering a sustainable solution to combat antibiotic resistance. Additionally, innovations in cost-effective microalgae cultivation techniques, such as optimized culture mediums and photobioreactors, are essential for making microalgal products economically viable. [Extracted from the article]

Background/Objectives: The current epidemic of drug-resistance bacterial strains is one of the most urgent threats to human health. Antimicrobial peptides (AMPs) are known for their good activity against multidrug resistance bacteria. Specifically targeted AMPs (STAMPs) are a fraction of AMPs that target specific bacteria and maintain the balance of the healthy microbiota of a host. We reported a STAMP Peptide K (former name: peptide 13) for E. coli. The aim of this study was to effectively produce peptide K using methylotrophic yeast Pichia pastoris. Methods: Three inserts (sequence of peptide K (K), two copies of peptide K fused with 2A sequence (KTK), and two copies of peptide K fused with 2A and an extra α mating factor (KTAK)) were designed to investigate the effect of the number of repeats and the trafficking of peptide on the yield. Results: The yield from KTK was the highest—more than two-fold higher compared with K—implying the role of the 2A sequence in heterologous peptide expression apart from the co-translation. Then, the fermentation condition for KTK was optimized. The optimized yield of KTK was 6.67 mg/mL, suggesting the efficiency of the expression system. Selectivity, antibacterial activity, biocompatibility, and the stability of the fermentation product were equivalent to the chemically synthesized peptide. The actional mechanism of the fermentation product included membrane permeabilization and ROS induction. Conclusions: Together, our work provided a new perspective to augment the yield of the antimicrobial peptide in the microbial system, building a technological foundation for their large-scale production and expanding the market application of AMPs. [ABSTRACT FROM AUTHOR]

Background: The persistence of antibiotic resistance has incited a strong interest in the discovery of agents with novel antimicrobial mechanisms. The direct killing of multidrug-resistant bacteria by cationic antimicrobial peptides (AMPs) underscores their importance in the fight against infections associated with antibiotic resistance. Despite a vast body of AMP literature demonstrating a plurality in structural classes, AMP engineering has been largely skewed toward peptides with idealized amphipathic helices (H-amphipathic). In contrast to helical amphipathicity, we designed a series of peptides that display the amphipathic motifs in the primary structure. We previously developed a rational framework for designing AMP libraries of H-amphipathic peptides consisting of Arg, Trp, and Val (H-RWV, with a confirmed helicity up to 88% in the presence of membrane lipids) tested against the most common MDR organisms. Methods: In this study, we re-engineered one of the series of the H-RWV peptides (8, 10, 12, 14, and 16 residues in length) to display the amphipathicity in the primary structure by side-by-side (linear) alignment of the cationic and hydrophobic residues into the 2 separate linear amphipathic (L-amphipathic) motifs. We compared the 2 series of peptides for antibacterial activity, red blood cell (RBC) lysis, killing and membrane-perturbation properties. Results: The L-RWV peptides achieved the highest antibacterial activity at a minimum length of 12 residues (L-RWV12, minimum optimal length or MOL) with the lowest mean MIC of 3–4 µM, whereas the MOL for the H-RWV series was reached at 16 residues (H-RWV16). Overall, H-RWV16 displayed the lowest mean MIC at 2 µM but higher levels of RBC lysis (25–30%), while the L-RWV series displayed minor RBC lytic effects at the test concentrations. Interestingly, when the S. aureus strain SA719 was chosen because of its susceptibility to most of the peptides, none of the L-RWV peptides demonstrated a high level of membrane perturbation determined by propidium iodide incorporation measured by flow cytometry, with <50% PI incorporation for the L-RWV peptides. By contrast, most H-RWV peptides displayed almost up to 100% PI incorporation. The results suggest that membrane perturbation is not the primary killing mechanism of the L-amphipathic RWV peptides, in contrast to the H-RWV peptides. Conclusions: Taken together, the data indicate that both types of amphipathicity may provide different ideal pharmacological properties that deserve further investigation. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is a growing public health challenge. Antimicrobial peptides (AMPs) effectively target microorganisms through non-specific mechanisms, limiting their ability to develop resistance. Therefore, the prediction and design of new AMPs is crucial. Recently, deep learning has spurred interest in computational approaches to peptide drug discovery. This study presents a novel deep learning framework for AMP classification, function prediction, and generation. We developed discoverAMP (dsAMP), a robust AMP predictor using CNN Attention BiLSTM and transfer learning, which outperforms existing classifiers. In addition, dsAMPGAN, a Generative Adversarial Network (GAN)-based model, generates new AMP candidates. Our results demonstrate the superior performance of dsAMP in terms of sensitivity, specificity, Matthew correlation coefficient, accuracy, precision, F1 score, and area under the ROC curve, achieving >95% classification accuracy with transfer learning on a small dataset. Furthermore, dsAMPGAN successfully synthesizes AMPs similar to natural ones, as confirmed by comparisons of physical and chemical properties. This model serves as a reliable tool for the identification of novel AMPs in clinical settings and supports the development of AMPs to effectively combat antibiotic resistance. [ABSTRACT FROM AUTHOR]

American Oyster Defensin (AOD) is a marine peptide that is derived from North American mussels. It has been demonstrated to exhibit potent antimicrobial activity and high safety in both in vitro and in vivo models. In this study, to facilitate synthesis, mutants of AOD with fewer disulfide bonds were designed and subjected to structural, antimicrobial, and anti-biofilm analysis. The antimicrobial activity of AOD-derived peptides decreased after reduction in the disulfide bond, and among its three derivatives, only AOD-1 inhibited very few bacteria with a MIC value of 64 μg/mL, whereas the others had no inhibitory effect on pathogenic bacteria. The findings demonstrated that full disulfide bonds are indispensable for bactericidal activity, with the α-helix playing a pivotal role in inhibiting bacterial membranes. Furthermore, the results of the ATP, ROS, membrane potential, and membrane fluidity assays demonstrated that intracellular ATP, reactive oxygen species, and membrane fluidity were all increased, while membrane potential was reduced. This indicated that AOD resulted in the impairment of membrane fluidity and induced metabolic disorders, ultimately leading to bacterial death. The inhibitory effect of AOD on the biofilm of S. epidermidis G-81 was determined through the crystal violet and confocal microscopy. The results demonstrated that AOD exhibited a notable inhibitory impact on the biofilm of S. epidermidis G-81. The minimum biofilm inhibitory concentration of AOD on S. epidermidis G-81 was 16 μg/mL, and the minimum biofilm scavenging concentration was 32 μg/mL, which exhibited superior efficacy compared to that of lincomycin. The inhibitory effect on the primary biofilm was 90.3%, and that on the mature biofilm was 82.85%, with a dose-dependent inhibition effect. Concurrently, AOD cleared intra-biofilm organisms and reduced the number of biofilm-holding bacteria by six orders of magnitude. These data indicate that disulfide bonds are essential to the structure and activity of AOD, and AOD may potentially become an effective dual-action antimicrobial and anti-biofilm agent. [ABSTRACT FROM AUTHOR]

Dental caries is one of the most prevalent and costly biofilm‐induced oral diseases that causes the deterioration of the mineralized tooth tissue. Traditional antimicrobial agents like antibiotics and antimicrobial peptides (AMPs) struggle to effectively eradicate bacteria in biofilms without eliciting resistance. Herein, we demonstrate the construction of FeOOH@Fe‐Lysine@Au nanostructured AMPs (nAMPs) distinguished by their AMP‐like antibacterial activity and self‐producing reactive oxygen species (ROS) capacity for caries treatment. On the one hand, FeOOH@Fe‐Lysine@Au nAMPs can catalyze glucose oxidation to generate ROS within the cariogenic biofilm microenvironment, resulting in the disintegration of the extracellular polymeric substance matrix and the exposure of bacteria. On the other hand, FeOOH@Fe‐Lysine@Au nAMPs can attach to bacterial surfaces via electrostatic attractions, proceeding to damage membranes, disrupt metabolic pathways, and inhibit protein synthesis through the aggregated lysine and the generated ROS. Based on this antibacterial mechanism, FeOOH@Fe‐Lysine@Au nAMPs can effectively eradicate Streptococcus mutans and its associated biofilm, significantly impeding the progression of dental caries. Given the straightforward and cost‐efficient preparation of FeOOH@Fe‐Lysine@Au nAMPs compared to AMPs that require specific sequences, and their minimal adverse impacts on gingival/palatal tissues, major organs, and oral/gut microbiomes, our research may promote the development of novel therapeutic agents in dental health maintenance. [ABSTRACT FROM AUTHOR]

Despite their relatively short lifespan, neutrophils are tasked with counteracting pathogens through various functions, including phagocytosis, production of reactive oxygen species, neutrophil extracellular traps (NETs), and host defense peptides. Regarding the latter, small cationic cathelicidins present a conundrum in neutrophil function. Although primarily recognized as microbicides with an ability to provoke pores in microbial cell walls, the ability of cathelicidin to modulate key neutrophil functions is also of great importance, including the release of chemoattractants, cytokines, and reactive oxygen species, plus prolonging neutrophil lifespan. Cumulative evidence indicates a less recognized role of cathelicidin as an "immunomodulator"; however, this term is not always explicit, and its relevance in neutrophil responses during infection and inflammation is seldom discussed. This review compiles and discusses studies of how neutrophils use cathelicidin to respond to infections, while also acknowledging immunomodulatory aspects of cathelicidin through potential crosstalk between sources of the peptide. [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]

The significant reduction in agricultural output and the decline in product quality are two of the most glaring negative impacts caused by plant pathogenic fungi (PPF). Furthermore, contaminated food or transit might introduce mycotoxins produced by PPF directly into the food chain. Eating food tainted with mycotoxin is extremely dangerous for both human and animal health. Using fungicides is the first choice to control PPF or their toxins in food. Fungicide resistance and its effects on the environment and public health are becoming more and more of a concern, despite the fact that chemical fungicides are used to limit PPF toxicity and control growth in crops. Fungicides induce target site alteration and efflux pump activation, and mutations in PPF result in resistance. As a result, global trends are shifting away from chemically manufactured pesticides and toward managing fungal plant diseases using various biocontrol techniques, tactics, and approaches. However, surveillance programs to monitor fungicide resistance and their environmental impact are much fewer compared to bacterial antibiotic resistance surveillance programs. In this review, we discuss the PPF that contributes to disease development in plants, the fungicides used against them, factors causing the spread of PPF and the emergence of new strains, the antifungal resistance mechanisms of PPF, health, the environmental impacts of fungicides, and the use of biocontrol agents (BCAs), antimicrobial peptides (AMPs), and nanotechnologies to control PPF as a safe and eco-friendly alternative to fungicides. [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]

Pneumococcal infections caused by Streptococcus pneumoniae are a leading cause of morbidity and mortality globally, particularly among children. The ability of S. pneumoniae to form enduring biofilms makes treatment inherently difficult, and options are further limited by emerging antibiotic resistance. The discovery of new antibiotics, particularly those with antibiofilm activity, is therefore increasingly important. Antimicrobial proteins and peptides (AMPs) from marine invertebrates are recognised as promising pharmacological leads. This study determined the in vitro antibacterial activity of hemolymph and unique protein fractions from an Australian oyster (Saccostrea glomerata) against multi-drug-resistant S. pneumoniae. We developed a successful method for hemolymph extraction and separation into 16 fractions by preparative HPLC. The strongest activity was observed in fraction 7: at 42 µg/mL protein, this fraction was bactericidal to S. pneumoniae and inhibited biofilm formation. Proteomic analysis showed that fraction 7 contained relatively high abundance of carbonic anhydrase, cofilin, cystatin B–like, and gelsolin-like proteins, while surrounding fractions, which showed lower or no antibacterial activity, contained these proteins in lower abundance or not at all. This work supports traditional medicinal uses of oysters and contributes to further research and development of novel hemolymph/AMP-based treatments for pneumococcal infections. [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: Cationic antimicrobial peptides (AMPs) possess broad‐spectrum biological activities with less inclination to inducing antibiotic resistance. Herein a battery of amphiphilic amidines were designed by mimicking the characteristics of AMPs. The antifungal activities and the effects to the hyphal morphology and membrane permeability were investigated. RESULTS: The results indicated the inhibitory rates of ten compounds were over 80% to Botrytis cinerea and ten compounds over 90% to Valsa mali Miyabe et Yamada at 50 mg L−1. The half maximal effective concentration (EC50) values of compound 5g and 6g to V. mali were 1.21 and 1.90 mg L−1 respectively. The protective rate against apple canker of compound 5g reached 93.4% at 100 mg L−1 on twigs, superior to carbendazim (53.3%). When treated with 5g, the cell membrane permeability and leakage of content of V. mali increased, accompanied with the decrease of superoxide dismutase (SOD) and catalase (CAT) level. Concurrently, the mycelial hyphae contracted, wrinkled, and collapsed, providing evidence of membrane perturbation. A three‐dimensional quantitative structure–activity relationship (3D‐QSAR) between the topic compounds and the EC50 to V. mali was established showing good predictability (r2 = 0.971). CONCLUSION: Amphiphilic amidines can acquire antifungal activities by acting on the plasmic membrane. Compound 5g could be a promising lead in discovering novel fungicidal candidates. © 2024 Society of Chemical Industry. [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]

Antimicrobial resistance is a global healthcare challenge that urgently needs the development of new therapeutic agents. Antimicrobial peptides and mimics thereof are promising candidates but mostly suffer from inherent toxicity issues due to the non‐selective binding of cationic groups with mammalian cells. To overcome this toxicity issue, this work herein reports the synthesis of a smart antimicrobial dendron with masked cationic groups (Gal‐Dendron) that could be uncaged in the presence of β‐galactosidase enzyme to form the activated Enz‐Dendron and confer antimicrobial activity. Enz‐Dendron show bacteriostatic activity toward Gram‐negative (P. aeruginosa and E. coli) and Gram‐positive (S. aureus) bacteria with minimum inhibitory concentration values of 96 µm and exerted its antimicrobial mechanism via a membrane disruption pathway, as indicated by inner and outer membrane permeabilization assays. Crucially, toxicity studies confirmed that the masked prodrug Gal‐Dendron exhibited low hemolysis and is at least 2.4 times less toxic than the uncaged cationic Enz‐Dendron, thus demonstrating the advantage of masking the cationic groups with responsive immolative linkers to overcome toxicity and selectivity issues. Overall, this study highlights the potential of designing new membrane‐disruptive antimicrobial agents that are more biocompatible via the amine uncaging strategy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Garlic is a promising source of antimicrobial peptide separation, and chemical modification is an effective method for activity improvement. The present study aimed to improve the antifungal activity of a peptide extracted from garlic. Chemical modifications were conducted, and the structure–activity relationship and antifungal mechanism were investigated. RESULTS: The results indicated that the cationic charge induced by Lys residue at the N‐terminal was important for the antimicrobial activity, and the modified sequence exhibited significant antifungal activity with low mammalian toxicity and a low tendency of drug resistance (p < 0.05). The structure–activity relationship analysis revealed that the modified active peptide had a predominant α‐helical structure and an inner cyclic correlation. Transcriptomic analysis showed that peptide KMLKKLFR (Lys‐Met‐Leu‐Lys‐Lyse‐Leu‐Phe‐Arg) affected the rRNA processing and carbon metabolism process of Candida albicans. In addition, the membrane potential study indicated a non‐membrane destruction mechanism, and molecular docking analysis and a DNA interaction assay suggested promising inner targets. CONCLUSION: The results of the present study indicate that chemical modification by amino acid substitution was effective for antimicrobial activity improvement. The present study would benefit future antimicrobial peptide development and suggests that garlic is a great source of antibacterial peptides and peptide template separations for coping with antibiotic resistance. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]