Project description:The balance between tolerogenic and inflammatory responses determines immune homeostasis in the gut. Dysbiosis and a defective host defense against invading intestinal bacteria can shift this balance via bacterial-derived metabolites and trigger chronic inflammation. We show that the short chain fatty acid butyrate modulates monocyte to macrophage differentiation by promoting antimicrobial effector functions. The presence of butyrate modulates antimicrobial activity via a shift in macrophage metabolism and reduction in mTOR activity. This mechanism is furthermore dependent on the inhibitory function of butyrate on histone deacetylase 3 (HDAC3) driving transcription of a set of antimicrobial peptides including calprotectin. The increased antimicrobial activity against several bacterial species is not associated with increased production of conventional cytokines. Butyrate imprints antimicrobial activity of intestinal macrophages in vivo. Our data suggest that commensal bacteria derived butyrate stabilize gut homeostasis by promoting antimicrobial host defense pathways in monocytes that differentiate into intestinal macrophages.
Project description:Aiming to reduce food spoilage, the present study developed novel highly active food-grade preservatives affecting a wide range of bacteria. For this purpose, storage proteins were extracted from food plants. After enzymatic hydrolysis by the digestive protease chymotrypsin, the peptide profiles were analyzed by ultrahigh-performance micro-liquid chromatography–triple quadrupole time-of-flight tandem mass spectrometry. Virtual screening identified 21 potential antimicrobial peptides in chickpea legumin. Among those, the peptides Leg1 (RIKTVTSFDLPALRFLKL) and Leg2 (RIKTVTSFDLPALRWLKL) exhibited antimicrobial activity against 16 different bacteria, including pathogens, spoilage-causing bacteria and two antibiotic-resistant strains. Minimum inhibitory concentrations (MIC) down to 15.6 µM indicated 10–1,000-fold higher activity of the novel antimicrobial peptides compared to conventional food preservatives. Moreover, Leg1 and Leg2 showed bactericidal activity in bacterial suspension and during the storage of raw pork meat.
Project description:Herein, we used C. acnes as a model to elucidate the antimicrobial machinery of the TH17 subset. We generated C. acnes-specific antimicrobial TH17 clones (AMTH17) with varying antimicrobial activity against C. acnes, to enable us to study mechanisms by which TH17 cells kill bacteria. We show that C. acnes-induced AMTH17 clones represent a subset of CD4+ TEM and TEMRA cells. RNA-seq analysis of AMTH17 indicate transcripts encoding antimicrobial molecules such as GNLY, GZMB, PRF1 and histone H2B, whose expression correlates with killing activity. Additionally, we validated that AMTH17-mediated killing is a general mechanism that can target C. acnes and other bacterial species. Scanning electron microscopy reveal that AMTH17s can release T cell extracellular traps composed of lysine and arginine-rich histones such as H2B and H4 that entangle C. acnes. This study identifies a functionally distinct subpopulation of TH17 cells with an ability to secrete antimicrobial proteins and form extracellular T cell traps to capture and kill bacteria.
Project description:Reversal reactions (RR) in leprosy provide a unique opportunity to study the dynamics of the immune response against intracellular bacteria in humans. We performed RNA sequencing on paired skin biopsy specimens from nine leprosy patients before and during RR, identifying a 64-gene antimicrobial response signature that correlated with the concomitant decrease in Mycobacterium leprae bacilli in RR patients. The upstream regulators of this antimicrobial gene signature included both innate (IL-1β, TNF) and adaptive (IFN-γ, IL-17) cytokines, indicating induction of both Th1 and Th17 responses. By using a machine learning classifier to identify proteins with predicted membrane-permeating activity, we identified 28 additional antimicrobial genes including S100A8. We validated the antimicrobial activity of four proteins (S100A7, S100A8, CCL17, CCL19) against M. leprae in infected macrophages and axenic culture. Scanning electron microscopy revealed distinct morphological changes in bacterial membranes upon exposure to these antimicrobial proteins. Our findings illuminate the dynamic regulation of antimicrobial gene expression as part of the innate and adaptive immune response against M. leprae and identify new potential antimicrobial effectors in human host defense. These insights underscore the potential for therapeutic strategies aimed at enhancing Th1 and Th17 cell function to improve outcomes in mycobacterial infection in humans.
Project description:The surge of antimicrobial resistance in recent decades threatens efficacy of current antibiotics, particularly against Pseudomonas aeruginosa, a highly resistant gram-negative pathogen. The asymmetric outer membrane of P. aeruginosa combined with its array of efflux pumps provide a barrier to xenobiotic intracellular accumulation, thus making the discovery of novel drugs with whole cell antibacterial activity very challenging. We adapted PROSPECT, a genome-wide, target-based, whole cell screening strategy, to take a focused approach to discover small molecule probes with specific activity against engineered P. aeruginosa mutants depleted for essential proteins localized at the outer membrane. We identified BRD1401, a small molecule that has specific activity against a P. aeruginosa mutant depleted for the essential lipoprotein, OprL. Genetic studies identified a novel link between OprL and the non-essential, outer membrane β barrel protein, OprH, to modulate BRD1401 activity. BRD1401 directly bound to OprH to disrupt the known interaction between OprH and lipopolysaccharide (LPS) in vitro and in whole bacteria. OprH also biochemically interacted with OprL, thus providing a link between outer membrane and peptidoglycan in P. aeruginosa. Thus, a whole cell, multiplexed screen against P. aeruginosa identified a species-specific inhibitor and probe molecule that revealed novel pathogen biology.
Project description:The surge of antimicrobial resistance in recent decades threatens efficacy of current antibiotics, particularly against Pseudomonas aeruginosa, a highly resistant gram-negative pathogen. The asymmetric outer membrane of P. aeruginosa combined with its array of efflux pumps provide a barrier to xenobiotic intracellular accumulation, thus making the discovery of novel drugs with whole cell antibacterial activity very challenging. We adapted PROSPECT, a genome-wide, target-based, whole cell screening strategy, to take a focused approach to discover small molecule probes with specific activity against engineered P. aeruginosa mutants depleted for essential proteins localized at the outer membrane. We identified BRD1401, a small molecule that has specific activity against a P. aeruginosa mutant depleted for the essential lipoprotein, OprL. Genetic studies identified a novel link between OprL and the non-essential, outer membrane β barrel protein, OprH, to modulate BRD1401 activity. BRD1401 directly bound to OprH to disrupt the known interaction between OprH and lipopolysaccharide (LPS) in vitro and in whole bacteria. OprH also biochemically interacted with OprL, thus providing a link between outer membrane and peptidoglycan in P. aeruginosa. Thus, a whole cell, multiplexed screen against P. aeruginosa identified a species-specific inhibitor and probe molecule that revealed novel pathogen biology.
Project description:Honokiol (HNK), one of the main medicinal components in Magnolia officinalis, possesses antimicrobial activity against a variety of pathogenic bacteria and fungi.S. cerevisiae is a model eukaryote used for investigating the cellular and molecular mechanisms of anti-fungal drugs. To explore the molecular mechanism of its anti-fungal activity, we determined the effects of HNK on the mRNA expression profile of Saccharomyces cerevisiae using a DNA microarray approach.
Project description:Enterocin AS-48 is produced by Enterococcus faecalis S48 to compete with other bacteria in their environment. Due to its activity against various Gram positive and some Gram negative bacteria it has clear potential for use as a food preservative. Here, we studied the effect of enterocin AS-48 challenges on vegetative cells of Bacillus cereus ATCC 14579 by use of transcriptome analysis. Control: Wild type against Target: Enterocin AS-48 challenge A supplementary file containing processed data of all samples combined is linked below. Mn column is the lowess normalized LN (Target/Control).
Project description:We have employed a custom bioprospecing approach to identify cationic antimicrobial peptides from Komodo dragon plasma. Through these analyses we identified forty eight novel potential cationic antimicrobial peptides, with all but one of the identified peptides being derived from histone proteins. The antimicrobial effectiveness of eight of these peptides was evaluated against Pseudomonas aeruginosa 9027 and Staphylococcus aureus 25983, with seven peptides exhibiting antimicrobial activity against both microbes, and one only showing significant potency against Pseudomonas aeruginosa 9027. This study demonstrates the power and promise of our bioprospecting approach to CAMP discovery and it reveals the presence of a plethora of novel histone-derived antimicrobial peptides in the plasma of the dragon. These findings may have broader implications regarding the role that intact histones and histone-derived peptides play in defending the host from infection.
Project description:Infections associated with antimicrobial-resistant bacteria now represent a significant threat to human health using conventional therapy, necessitating the development of alternate and more effective antibacterial compounds. Silver nanoparticles (Ag NPs) have been proposed as potential antimicrobial agents to combat infections. A complete understanding of their antimicrobial activity is required before these molecules can be used in therapy. Lysozyme coated Ag NPs were synthesized and characterized by TEMEDS, XRD, UV-vis, FTIR spectroscopy, zeta potential, and oxidative potential assay. Biochemical assays and deep level transcriptional analysis using RNA sequencing were used to decipher how Ag NPs exert their antibacterial action against multi-drug resistant Klebsiella pneumoniae MGH78578. RNAseq data revealed that Ag NPs induced a triclosan-like bactericidal mechanism responsible for the inhibition of the type II fatty acid biosynthesis. Additionally, released AgC generated oxidative stress both extra and intracellularly in K. pneumoniae. The data showed that triclosan-like activity and oxidative stress cumulatively underpinned the antibacterial activity of Ag NPs. This result was confirmed by the analysis of the bactericidal effect of Ag NPs against the isogenic K. pneumoniae MGH78578 1soxS mutant, which exhibits a compromised oxidative stress response compared to the wild type. Silver nanoparticles induce a triclosan like antibacterial action mechanism in multi-drug resistant K. pneumoniae. This study extends our understanding of anti-Klebsiella mechanisms associated with exposure to Ag NPs. This allowed us to model how bacteria might develop resistance against silver nanoparticles, should the latter be used in therapy.