Endogenous Antimicrobial Peptides Research Articles

Prediction of enzyme action for extraction of antimicrobial substances from <i>Sus scrofa</i> and <i>Bos taurus</i>

The study of antimicrobial compounds of animal origin, particularly antimicrobial peptides (AMPs), is a current research topic. However, extracting endogenous AMPs is a challenging process and requires the application of targeted enzymatic processing principles based on knowledge of the structure of prepropeptide molecules — precursors of AMPs. In this study, a search was conducted for antimicrobial peptides present in Sus scrofa and Bos taurus organisms, as well as their precursors, using The Antimicrobial Peptide Database and UniProtKB databases. In the amino acid sequences of prepropeptides, the sequences of the mature peptides were found, and cleavage sites for trypsin, bacterial collagenase (type I), and neutrophil elastase were determined. As a result of the search for antimicrobial compounds in The Antimicrobial Peptide Database, 18 antimicrobial peptides from Sus scrofa and 40 antimicrobial peptides from Bos taurus were identified. Based on the results of determining cleavage sites in AMP precursors, enzymes were ranked from less preferred to more preferred for AMP release as follows: bacterial collagenase (type I) ≤ trypsin < neutrophil elastase. This order is justified not only by the number of suitable cleavage sites and their accuracy but also by the action of enzymes within mature AMPs: it is important to consider that enzymes can “cut” the peptides themselves, thereby reducing their antimicrobial activity. The bioinformatics analysis conducted is applicable for both primary screening of raw material potential and determining of suitable enzymes for extracting antimicrobial compounds from Sus scrofa and Bos taurus organisms.

A novel endogenous antimicrobial peptide MP-4 derived from koumiss of Inner Mongolia by peptidomics, and effects on Staphylococcus aureus

Koumiss is known as a traditional milk-based beverage with high nutritional value and antimicrobial potential. In this study, we investigated the antibacterial effects of koumiss-derived antimicrobial peptides against Staphylococcus aureus. Then, we used peptidomics to analyze and identify 2381 peptides from mare's milk and koumiss, of which 53.25% were significantly different before and after fermentation, and these peptides were mainly derived from caseins. Among the identified peptides, five new antimicrobial peptides with high antimicrobial potential, as measured by the scores of predicted peptide sequences in the antimicrobial peptide database, and validation of their antimicrobial activity and stability. MP-4 was found to have antimicrobial activity, and it exerted significant and stable antibacterial effects. The antimicrobial peptide MP-4 could inhibit Staphylococcus aureus by changing its morphology and killing it via the induction of protein leakage. Therefore, it can be concluded that MP-4 is a novel antimicrobial peptide derived from koumiss that has good antibacterial properties against Staphylococcus aureus. Our study provides a theoretical basis for the application of koumiss-derived peptides.

ASynPEP-DB: a database ofbiogenic peptides forinhibiting α-synuclein aggregation.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder, yet effective treatments able to stop or delay disease progression remain elusive. The aggregation of a presynaptic protein, α-synuclein (aSyn), is the primary neurological hallmark of PD and, thus, a promising target for therapeutic intervention. However, the lack of consensus on the molecular properties required to specifically bind the toxic species formed during aSyn aggregation has hindered the development of therapeutic molecules. Recently, we defined and experimentally validated a peptide architecture that demonstrated high affinity and selectivity in binding to aSyn toxic oligomers and fibrils, effectively preventing aSyn pathogenic aggregation. Human peptides with such properties may have neuroprotective activities and hold a huge therapeutic interest. Driven by this idea, here, we developed a discriminative algorithm for the screening of human endogenous neuropeptides, antimicrobial peptides and diet-derived bioactive peptides with the potential to inhibit aSyn aggregation. We identified over 100 unique biogenic peptide candidates and ensembled a comprehensive database (aSynPEP-DB) that collects their physicochemical features, source datasets and additional therapeutic-relevant information, including their sites of expression and associated pathways. Besides, we provide access to the discriminative algorithm to extend its application to the screening of artificial peptides or new peptide datasets. aSynPEP-DB is a unique repository of peptides with the potential to modulate aSyn aggregation, serving as a platform for the identification of previously unexplored therapeutic agents. Database URL: https://asynpepdb.ppmclab.com/.

Antimicrobial Activity of Ceragenins against Vancomycin-Susceptible and -Resistant Enterococcus spp.

Ceragenins (CSAs) are a new class of antimicrobial agents designed to mimic the activities of endogenous antimicrobial peptides. In this study, the antibacterial activities of various ceragenins (CSA-13, CSA-44, CSA-90, CSA-131, CSA-138, CSA-142, and CSA-192), linezolid, and daptomycin were assessed against 50 non-repeated Enterococcus spp. (17 of them vancomycin-resistant Enterococcus-VRE) isolated from various clinical specimens. Among the ceragenins evaluated, the MIC50 and MIC90 values of CSA-44 and CSA-192 were the lowest (2 and 4 μg/mL, respectively), and further studies were continued with these two ceragenins. Potential interactions between CSA-44 or CSA-192 and linezolid were tested and synergistic interactions were seen with the CSA-192-linezolid combination against three Enterococcus spp., one of them VRE. The effects of CSA-44 and CSA-192 on the MIC values of vancomycin were also investigated, and the largest MIC change was seen in the vancomycin-CSA-192 combination. The in vivo effects of CSA-44 and CSA-192 were evaluated in a Caenorhabditis elegans model system. Compared to no treatment, increased survival was observed with C. elegans when treated with ceragenins. In conclusion, CSA-44 and CSA-192 appear to be good candidates (alone or in combination) for the treatment of enterococcal infections, including those from VRE.

Identification and Characterization of RK22, a Novel Antimicrobial Peptide from Hirudinaria manillensis against Methicillin Resistant Staphylococcus aureus.

Staphylococcus aureus (S. aureus) infections are a leading cause of morbidity and mortality, which are compounded by drug resistance. By manipulating the coagulation system, S. aureus gains a significant advantage over host defense mechanisms, with hypercoagulation induced by S. aureus potentially aggravating infectious diseases. Recently, we and other researchers identified that a higher level of LL-37, one endogenous antimicrobial peptide with a significant killing effect on S. aureus infection, resulted in thrombosis formation through the induction of platelet activation and potentiation of the coagulation factor enzymatic activity. In the current study, we identified a novel antimicrobial peptide (RK22) from the salivary gland transcriptome of Hirudinaria manillensis (H. manillensis) through bioinformatic analysis, and then synthesized it, which exhibited good antimicrobial activity against S. aureus, including a clinically resistant strain with a minimal inhibitory concentration (MIC) of 6.25 μg/mL. The RK22 peptide rapidly killed S. aureus by inhibiting biofilm formation and promoting biofilm eradication, with good plasma stability, negligible cytotoxicity, minimal hemolytic activity, and no significant promotion of the coagulation system. Notably, administration of RK22 significantly inhibited S. aureus infection and the clinically resistant strain in vivo. Thus, these findings highlight the potential of RK22 as an ideal treatment candidate against S. aureus infection.

Molecular Cloning, Expression Analyses, and Physiological Roles of Cathelicidins in the Bursa of Fabricius of the Japanese Quail, Coturnix japonica

Antimicrobial peptides (AMPs) act directly on pathogens and maintain the anti-inflammatory effects and activation of immunocompetent cells. Therefore, the activation of the immune system in poultry via the elevation of endogenous AMPs has been attempted. In this study, we focused on the host defense mechanisms in the bursa of Fabricius (BF) of Japanese quail, cloned the cDNA of cathelicidin (CATH)-1 to -3, and analyzed their expression sites. In situ hybridization experiments revealed the mRNA expression of the CATHs in the interfollicular epithelium surrounding the lumen of the quail BF, which suggests that each CATH may exert its antimicrobial action directly in the BF. The intravenous injection of bacterial lipoteichoic acid and lipopolysaccharide endotoxins into the quail promoted the mRNA expression of CATH-1 and CATH-3 in the BF. The addition of CATH-1 or CATH-2 at the time of the antigen injection into mice resulted in antiserum with high antibody titers. Ad libitum administration of butyrate, a short-chain fatty acid, in the drinking water induced an increase in CATH-2 mRNA expression in the BF under certain conditions. These results may improve the defense mechanisms of quail by stimulating CATH expression in the BF through their diet.

Antibacterial and Antibiofilm Activities of Ceragenins Alone and in Combination with Levofloxacin Against Multidrug Resistant Myroides spp. Clinical Isolates from Patients with Urinary Tract Infections

Myroides spp. are rare opportunistic pathogens, but they can be life-threatening because of their multidrug-resistant drug properties and their potential to cause outbreaks, especially in immunosuppressed patients. In this study, 33 isolates isolated from intensive care patients with urinary tract infections were examined for drug susceptibility. All isolates except three proved to be resistant to the tested conventional antibiotics. The effects of ceragenins, a class of compounds developed to mimic endogenous antimicrobial peptides, were evaluated against these organisms. The MIC values of nine ceragenins were determined, and the most effective ceragenins were CSA-131 and CSA-138. Three isolates that were susceptible to levofloxacin and two isolates resistant to all antibiotics underwent 16s rDNA analysis, and whereas resistant isolates were identified as M. odoratus, susceptible isolates were identified as M. odoratimimus. CSA-131 and CSA-138 showed rapid antimicrobial effects observed in time-kill analyses. Combinations of ceragenins and levofloxacin caused a significant increase in antimicrobial and antibiofilm activities against M. odoratimimus isolates. In this study, Myroides spp. were found to be multidrug-resistant and have biofilm forming capacity, and ceragenins CSA-131 and CSA-138 were found to be especially effective on both planktonic and biofilm forms of Myroides spp.

Hindbrain ghrelin and liver-expressed antimicrobial peptide 2, ligands for growth hormone secretagogue receptor, bidirectionally control food intake.

Hindbrain growth hormone secretagogue receptor (GHSR) agonism increases food intake, yet the underlying neural mechanisms remain unclear. The functional effects of hindbrain GHSR antagonism by its endogenous antagonist liver-expressed antimicrobial peptide 2 (LEAP2) are also yet unexplored. To test the hypothesis that hindbrain GHSR agonism attenuates the food intake inhibitory effect of gastrointestinal (GI) satiation signals, ghrelin (at a feeding subthreshold dose) was administered to the fourth ventricle (4V) or directly to the nucleus tractus solitarius (NTS) before systemic delivery of the GI satiation signal cholecystokinin (CCK). Also examined, was whether hindbrain GHSR agonism attenuated CCK-induced NTS neural activation (c-Fos immunofluorescence). To investigate an alternate hypothesis that hindbrain GHSR agonism enhances feeding motivation and food seeking, intake stimulatory ghrelin doses were administered to the 4V and fixed ratio 5 (FR-5), progressive ratio (PR), and operant reinstatement paradigms for palatable food responding were evaluated. Also assessed were 4V LEAP2 delivery on food intake and body weight (BW) and on ghrelin-stimulated feeding. Both 4V and NTS ghrelin blocked the intake inhibitory effect of CCK and 4V ghrelin blocked CCK-induced NTS neural activation. Although 4V ghrelin increased low-demand FR-5 responding, it did not increase high-demand PR or reinstatement of operant responding. Fourth ventricle LEAP2 reduced chow intake and BW and blocked hindbrain ghrelin-stimulated feeding. Data support a role for hindbrain GHSR in bidirectional control of food intake through mechanisms that include interacting with the NTS neural processing of GI satiation signals but not food motivation and food seeking.

Induction of Endogenous Antimicrobial Peptides to Prevent or Treat Oral Infection and Inflammation

Antibiotics are often used to treat oral infections. Unfortunately, excessive antibiotic use can adversely alter oral microbiomes and promote the development of antibiotic-resistant microorganisms, which can be difficult to treat. An alternate approach could be to induce the local transcription and expression of endogenous oral antimicrobial peptides (AMPs). To assess the feasibility and benefits of this approach, we conducted literature searches to identify (i) the AMPs expressed in the oral cavity; (ii) the methods used to induce endogenous AMP expression; and (iii) the roles that expressed AMPs may have in regulating oral inflammation, immunity, healing, and pain. Search results identified human neutrophil peptides (HNP), human beta defensins (HBD), and cathelicidin AMP (CAMP) gene product LL-37 as prominent AMPs expressed by oral cells and tissues. HNP, HBD, and LL-37 expression can be induced by micronutrients (trace elements, elements, and vitamins), nutrients, macronutrients (mono-, di-, and polysaccharides, amino acids, pyropeptides, proteins, and fatty acids), proinflammatory agonists, thyroid hormones, and exposure to ultraviolet (UV) irradiation, red light, or near infrared radiation (NIR). Localized AMP expression can help reduce infection, inflammation, and pain and help oral tissues heal. The use of a specific inducer depends upon the overall objective. Inducing the expression of AMPs through beneficial foods would be suitable for long-term health protection. Additionally, the specialized metabolites or concentrated extracts that are utilized as dosage forms would maintain the oral and intestinal microbiome composition and control oral and intestinal infections. Inducing AMP expression using irradiation methodologies would be applicable to a specific oral treatment area in addition to controlling local infections while regulating inflammatory and healing processes.

Bioactive Peptide Discovery from Edible Insects for Potential Applications in Human Health and Agriculture.

In the past decade, there has been fast-growing interest among researchers to discover bioactive peptides from edible insects and to evaluate their potential applications in the management of human, livestock, and plant health. This review summarizes current knowledge of insect-derived peptides and their potential role in tackling human health issues and solving agriculture problems by protecting crops and livestock against their pathogens. Numerous bioactive peptides have been identified from edible insect species, including peptides that were enzymatically liberated from insect proteins and endogenous peptides that occur naturally in insects. The peptides exhibited diverse bioactivities, encompassing antioxidant, anti-angiotensin-converting enzyme, anti-dipeptidyl peptidase-IV, anti-glucosidase, anti-lipase, anti-lipoxygenase, anti-cyclooxygenase, anti-obesity, and hepatoprotective activities. Such findings point to their potential contribution to solving human health problems related to inflammation, free radical damage, diabetes, hypertension, and liver damage, among others. Although most of the experiments were performed in vitro, evidence for the in vivo efficacy of some peptides is emerging. Evidence of the protective effects of insect-derived endogenous antimicrobial peptides in combating farm animal and plant pathogens is available. The ability of insect-derived endogenous neuropeptides to protect plants against herbivorous insects has been demonstrated as well. Nevertheless, the potency of peptides identified from insect protein hydrolysates in modulating livestock and plant health remains a knowledge gap to be filled.

A Designed Host Defense Peptide for the Topical Treatment of MRSA-Infected Diabetic Wounds.

Diabetes mellitus is a chronic disease characterized by metabolic dysregulation which is frequently associated with diabetic foot ulcers that result from a severely compromised innate immune system. The high levels of blood glucose characteristic of diabetes cause an increase in circulating inflammatory mediators, which accelerate cellular senescence and dampen antimicrobial activity within dermal tissue. In diabetic wounds, bacteria and fungi proliferate in a protective biofilm forming a structure that a compromised host defense system cannot easily penetrate, often resulting in chronic infections that require antimicrobial intervention to promote the healing process. The designed host defense peptide (dHDP) RP557 is a synthesized peptide whose sequence has been derived from naturally occurring antimicrobial peptides (AMPs) that provide the first line of defense against invading pathogens. AMPs possess an amphipathic α-helix or β-sheet structure and a net positive charge that enables them to incorporate into pathogen membranes and perturb the barrier function of Gram-positive and Gram-negative bacteria along with fungi. The capacity of skin to resist infections is largely dependent upon the activity of endogenous AMPs that provided the basis for the design and testing of RP557 for the resolution of wound infections. In the current study, the topical application of RP557 stopped bacterial growth in the biofilm of methicillin-resistant Staphylococcus aureus (MRSA) USA300 infected wounds on the flanks of clinically relevant diabetic TALLYHO mice. Topical application of RP557 reduced bacterial load and accelerated wound closure, while wound size in control diabetic mice continued to expand. These studies demonstrate that RP557 reduces or eliminates an infection in its biofilm and restores wound-healing capacity.

Serum human β-defensin-1 (hBD-1) and -20G/A DEFB1 gene polymorphism in Behçet’s disease patients: Relation to clinical characteristics

Aim of the work:Behçet’s disease (BD) is a multisystemic inflammatory disease of unknown cause. Beta defensins (β-defensins) are endogenous antimicrobial peptides that have the ability to kill or inactivate a wide spectrum of bacteria and fungi by changing their membranes stability. It also plays a significant role in inflammation owing to its chemotactic activity for T cells and immature dendritic cells. To explore whether β-defensins might be involved in BD pathogenesis, serum human β-defensin-1 (hBD-1) and defensin-β-1 (DEFB1)-20 G/A gene polymorphism were assessed in patients with BD. Patients and methodsThe study included 40 BD patients and 40 matched controls. Serum hBD-1 was assessed by enzyme-linked immunosorbent assay (ELISA) and the -20G/A genotypes (rs11362) were determined by restriction fragment length polymorphism-polymerase chain reaction(RFLP-PCR) analysis. ResultsThe mean age of patients was 33.5 ± 10.8 years. They were 32 males and 8 females (M:F 4:1). Disease duration was 8.5 ± 7.3 years. In patients, the median serum hBD-1 concentration was 295.5 pg/ml (27.6–1776.6 pg/ml) and was significantly higher than in the control (median 129.6 pg/ml; 23.7–986.3 pg/ml) (p < 0.001). Serum hBD-1 significantly correlated with C-reactive protein (r = 0.85, p = 0.001) and platelets (r = 0.4, p = 0.012). No significant difference was found between patients and control regarding genotyping of -20G/A DEFB1 (rs11362). Skin manifestations were significantly higher among patients with GA genotype 18/23 (78.2 %) than patients with AA genotype 7/16 (43.8 %)(p = 0.027). However, there was no association between serum hBD-1 and −20A/G polymorphism. ConclusionsThe hBD-1 is implicated in the pathogenesis of BD and may be a possible therapeutic target.

Andrographolide and 4-Phenylbutyric Acid Administration Increase the Expression of Antimicrobial Peptides Beta-Defensin-1 and Cathelicidin and Reduce Mortality in Murine Sepsis.

Antibiotic resistance is a global threat and requires the search for new treatment strategies. Natural antimicrobial peptides (AMPs) have pronounced antibacterial, antiviral, antifungal, and antitumor activity. AMPs' clinical use is complicated by the high synthesis costs and rapid proteolytic degradation. The search for small molecules, inducers of endogenous AMP expression, could become a new approach. Here, we investigated for the first time the effect of seven small molecules (andrographolide, levofloxacin, azithromycin, montelukast, 4-phenylbutyric acid, rosuvastatin and valsartan) on AMP (beta-defensin-1, hBD-1 and cathelicidin, LL-37) serum levels in rats. In control groups, the level of hBD-1 was 295.0 (292.9-315.4) pg/mL, and for LL-37, it was 223.8 (213.3-233.6) pg/mL. Andrographolide (ANDR) and 4-phenylbutyric acid (4-PHBA) administration significantly enhanced the level of both AMPs. The hBD-1 level was 581.5 (476.3-607.7) pg/mL for ANDR and 436.9 (399.0-531.6) pg/mL for 4-PHBA. The LL-37 level was 415.4 (376.2-453.8) pg/mL for ANDR and 398.9 (355.7-410.1) pg/mL for 4-PHBA. Moreover, we have shown that these compounds reduce mortality in a murine model of sepsis caused by a carbapenem-resistant Klebsiella aerogenes isolate. From our point of view, these small molecules are promising candidates for further study as potent AMP inducers. The data obtained allow the development of new strategies to combat antibiotic resistance and infectious diseases.

Cyclosporin A acts as a novel insecticide against Cry1Ac-susceptible and -resistant Helicoverpa armigera

Cotton bollworm (Helicoverpa armigera) is an economically important pest, which is difficult to manage due to its biological and ecological traits, and resistance to most insecticides. Alternative compounds for the sustainable management of H. armigera are needed. As a fungal metabolite, Cyclosporin A (CsA) has not been applied in agriculture pests. Here, CsA was evaluated as a propective insecticide for H. armigera. The results showed that CsA displayed high insecticidal activity against both Cry1Ac-susceptible and -resistant populations of H. armigera. Moreover, lower concentrations of CsA had clear effects, including significantly reduced pupal weight, pupation rate, emergence rate, ovary size, female fecundity and egg hatchability. Further study confirmed that CsA suppressed calcineurin activity and the subsequent expression of endogenous antimicrobial peptide genes (APMs), leading to impaired immunity, ultimately resulting in delayed development and increased mortality. Thus, CsA treatment could control the cotton bollworm population and even showed efficacy against those with Bt resistance. In addition, the morphological changes observed in insects fed CsA with lower concentrations provide insight into insect immunity, regulation of growth and development, regulation of body color, ovary development and sexual selection under external pressure. Overall, our study provides information on biological control potential of Cry1Ac-susceptible and -resistant populations of H. armigera to develop novel bioinsecticides.

Антимікробні пептиди (HNPs 1-3 та LL-37) як біомаркери активності запального процесу в дітей, хворих на H. pylori-асоційовану виразку дванадцятипалої кишки

Various gastrointestinal and extragastrointestinal diseases are associated with H. pylori in children and adolescents, but the strongest recommendations for testing and treatment are made only in children and adolescents with duodenal ulcer (DU). The inability of natural immune mechanisms to recognize and eliminate H. pylori leads to the development of acute inflammation. The most promising developments so far are studies of the antibacterial effect of endogenous antimicrobial peptides (AP), among which defensines 1-3 (human neutrophil peptides, HNPs 1-3) and cathelicidins (LL-37) are the most important for the human body. Purpose - to investigate the concentration of HNPs 1-3 and LL-37 in the blood of children with DU in order to determine the activity of the inflammatory process of the mucous membrane. Materials and methods. 65 children aged 7-18 years, suffering from DU and 25 healthy children of the corresponding age (comparison group) were examined. The level of HNPs 1-3 and LL-37 was determined in blood plasma by enzyme-linked immunosorbent assay according to the manufacturers instructions. Results. Patients were divided by age, sex, location and size of the ulcer, presence of the H. pylori bacterium. A toxigenic strain of H. pylori was detected in 80.9% of examined children, and the level of HNPs 1-3 in blood plasma was 3 times higher and the level of LL-37 was 2.5 times higher in children with H. pylori-associated DU than in healthy children (p=0.01). Concentrations of HNPs 1-3 and LL-37 in blood plasma were higher in patients with an active inflammatory process in the mucous membrane and were positively correlated with the degree of inflammation activity (r=0.67, p=0.05 and r=0.69, p=0.01). After eradication therapy, AP levels decrease, while the degree of decrease directly depends on the activity of the inflammatory process. Conclusions. Probably higher concentrations of HNPs 1-3 and LL-37 were found in the blood plasma of children with H. pylori-associated DU. Considering the direct correlations between the levels of HNPs 1-3 and LL-37 and the degree of activity of the inflammatory process, these indicators can be used as biomarkers of the adverse course of H. pylori-associated DU. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

The effect of endogenous antimicrobial peptides (HNPs1-3 and LL-37) on the course of duodenal ulcer in children

Introduction. Duodenal ulcer in children is characterized by a significant prevalence, frequent development of serious complications and the need for large financial allocations for the implementation of treatment programs. Antimicrobial peptides have an immunomodulatory function and can be used as markers of the severity of the inflammatory process.Aim. To investigate the concentration of HNPs 1-3 and LL-37 in children with duodenal ulcer.Methods. A study of 47 children with duodenal ulcer, aged 7–18 years, was conducted with the determination of the CagA HR antigen in feces by enzyme-linked immunosorbent assay, the levels of HNPs 1-3 and LL-37 in blood plasma by enzyme-linked immunosorbent assay on the "PrisMatic" IN013 model 4301 analyzer test systems "MyBioSource, Inc.", USA. All children underwent a complex clinical and instrumental laboratory examination (topographic intragastric pH-metry, endoscopic examination with targeted biopsy for morphological examination and determination of HP). Results. 76.6% of people with DU were infected with HP. 80% had a toxigenic CagA strain of HP. In the vast majority of children with DU, small ulcerative defects were diagnosed. II and III degrees of inflammatory activity occurred with almost the same frequency (44.6% and 34% of people), while I degree occurred only in 21.3% of cases. The average level of HNP1-3 in children with DU was 46.56 ± 8.52 ng/ml, LL-37 - 269.9 ± 26.53 ng/ml. Direct probable connections between the levels of HNP1-3 and LL-37 and the severity of the course and the activity of the inflammatory process were established.Conclusion. Elevated levels of LL-37 and HNPs 1-3 were found in the blood plasma of children with duodenal ulcers associated with CagA strains of Helicobacter pylori. Significantly higher levels of LL-37 and HNPs 1-3 were registered with a severe course of the disease and an active inflammatory process, which indicates a direct influence of antimicrobial peptides on the course of the pathological process.

Cathelicidin LL-37 level in presence and absence of vitamin D in cultured macrophages isolated from elderly women

Introduction: Vitamin D deficiency and frequent infections are the two common worldwide phenomenon among elderly. Recent studies have demonstrated that vitamin D regulates the expression of specific endogenous antimicrobial peptides like cathelicidin LL-37 of macrophages and neutrophils, which is active against a broad spectrum of infectious agents. Therefore, the objective of the present study was to determine the level of cathelicidin LL-37 in macrophages of elderly women (classified according to serum 25(OH)D level) after exposure to Vibrio cholera infection and to find out the effect of 1,25(OH)2D added in vitro. Methods: This study was conducted among 40 randomly selected rural elderly women aged between 60 to 70 years of age. Their vitamin D status was assessed by the estimation of serum 25(OH)D and classified into three groups viz. sufficient (14 members), insufficient (13 members), and deficient (13 members). Later, their peripheral blood mononuclear cells (PBMC) were isolated and cultured from fresh blood. 1,25(OH)2D supplementation was given selectively at a dose of 10 ×10-8 M for 72 hours in the culture media; then exposed to infection and screened according to the objectives of this study. Results: Macrophages in all groups, except vitamin D deficient group, responded significantly in terms of LL-37 release during exposure to Vibrio cholera infection. Considering in vitro 1,25(OH)2D, supplementation responded significantly (p&lt;0.05) in all three groups. Conclusion: Vitamin D can be used as a prophylaxis to enhance cathelicidin LL-37 release for all three groups as in the present study.

The antimicrobial peptides secreted by the chromaffin cells of the adrenal medulla link the neuroendocrine and immune systems: From basic to clinical studies.

The increasing resistance to antibiotic treatments highlights the need for the development of new antimicrobial agents. Antimicrobial peptides (AMPs) have been studied to be used in clinical settings for the treatment of infections. Endogenous AMPs represent the first line defense of the innate immune system against pathogens; they also positively interfere with infection-associated inflammation. Interestingly, AMPs influence numerous biological processes, such as the regulation of the microbiota, wound healing, the induction of adaptive immunity, the regulation of inflammation, and finally express anti-cancer and cytotoxic properties. Numerous peptides identified in chromaffin secretory granules from the adrenal medulla possess antimicrobial activity: they are released by chromaffin cells during stress situations by exocytosis via the activation of the hypothalamo-pituitary axis. The objective of the present review is to develop complete informations including (i) the biological characteristics of the AMPs produced after the natural processing of chromogranins A and B, proenkephalin-A and free ubiquitin, (ii) the design of innovative materials and (iii) the involvement of these AMPs in human diseases. Some peptides are elective biomarkers for critical care medicine, may play an important role in the protection of infections (alone, or in combination with others or antibiotics), in the prevention of nosocomial infections, in the regulation of intestinal mucosal dynamics and of inflammation. They could play an important role for medical implant functionalization, such as catheters, tracheal tubes or oral surgical devices, in order to prevent infections after implantation and to promote the healing of tissues.

A non-canonical role of caspase-1 in regulating bacterial physiology and antimicrobial resistance

Abstract Caspase-1 is a key effector molecule involved in inflammasome activation and has a well-established role in restricting the growth of intracellular pathogens like Salmonella by triggering a form of cell death called pyroptosis. Here we reveal a non-canonical, cell death independent role for caspase-1 in controlling the transcriptional state and drug resistance of intracellular Salmonella. Using Pathogen-sequencing, a method for sensitive transcriptional profiling of miniscule numbers of intracellular bacteria from infected macrophages, we show that that caspase-1 regulates key processes involved in survival and antimicrobial susceptibility of intracellular Salmonella. Host caspase-1 increased susceptibility of Salmonella to endogenous cationic antimicrobial peptides, as well as to a cationic polypeptide antibiotic used as a last-line drug in Gram-negative bacterial infections. These effects of caspase-1 were independent of its enzymatic activity but dependent on its ability to repress activation of a two-component signal transduction system in intracellular bacteria. These effects were also independent of caspase-11. Our data suggest a “backup” role for caspase-1 in dampening antimicrobial resistance of intracellular Salmonella which evade initial innate immune detection and restriction by caspase-1. These findings also reveal the role of a key innate immune effector in altering pathogen physiology, broadening our view of host-pathogen crosstalk with possible implications for targeting caspase-1 in host-directed therapy to combat antimicrobial resistance. Supported by grant from NIH (R01 AI155685-A1 ) and AAI Careers in Immunology Fellowship (2018-2019)

Catestatin selects for colonization of antimicrobial-resistant gut bacterial communities.

The gut microbiota is in continuous interaction with the innermost layer of the gut, namely the epithelium. One of the various functions of the gut epithelium, is to keep the microbes at bay to avoid overstimulation of the underlying mucosa immune cells. To do so, the gut epithelia secrete a variety of antimicrobial peptides, such as chromogranin A (CgA) peptide catestatin (CST: hCgA352-372). As a defense mechanism, gut microbes have evolved antimicrobial resistance mechanisms to counteract the killing effect of the secreted peptides. To this end, we treated wild-type mice and CST knockout (CST-KO) mice (where only the 63 nucleotides encoding CST have been deleted) with CST for 15 consecutive days. CST treatment was associated with a shift in the diversity and composition of the microbiota in the CST-KO mice. This effect was less prominent in WT mice. Levels of the microbiota-produced short-chain fatty acids, in particular, butyrate and acetate were significantly increased in CST-treated CST-KO mice but not the WT group. Both CST-treated CST-KO and WT mice showed a significant increase in microbiota-harboring phosphoethanolamine transferase-encoding genes, which facilitate their antimicrobial resistance. Finally, we show that CST was degraded by Escherichia coli via an omptin-protease and that the abundance of this gene was significantly higher in metagenomic datasets collected from patients with Crohn's disease but not with ulcerative colitis. Overall, this study illustrates how the endogenous antimicrobial peptide, CST, shapes the microbiota composition in the gut and primes further research to uncover the role of bacterial resistance to CST in disease states such as inflammatory bowel disease.