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MBio Aug 2021The gut microbiota affects the physiology and metabolism of animals and its alteration can lead to diseases such as gut dysplasia or metabolic disorders. Several reports...
The gut microbiota affects the physiology and metabolism of animals and its alteration can lead to diseases such as gut dysplasia or metabolic disorders. Several reports have shown that the immune system plays an important role in shaping both bacterial community composition and abundance in , and that immune deficit, especially during aging, negatively affects microbiota richness and diversity. However, there has been little study at the effector level to demonstrate how immune pathways regulate the microbiota. A key set of immune effectors are the antimicrobial peptides (AMPs), which confer defense upon systemic infection. AMPs and lysozymes, a group of digestive enzymes with antimicrobial properties, are expressed in the gut and are good candidates for microbiota regulation. Here, we take advantage of the model organism Drosophila melanogaster to investigate the role of AMPs and lysozymes in regulation of gut microbiota structure and diversity. Using flies lacking AMPs and newly generated lysozyme mutants, we colonized gnotobiotic flies with a defined set of commensal bacteria and analyzed changes in microbiota composition and abundance in vertical transmission and aging contexts through 16S rRNA gene amplicon sequencing. Our study shows that AMPs and, to a lesser extent, lysozymes are necessary to regulate the total and relative abundance of bacteria in the gut microbiota. We also decouple the direct function of AMPs from the immune deficiency (IMD) signaling pathway that regulates AMPs but also many other processes, more narrowly defining the role of these effectors in the microbial dysbiosis observed in IMD-deficient flies upon aging. This study advances current knowledge in the field of host-microbe interactions by demonstrating that the two families of immune effectors, antimicrobial peptides and lysozymes, actively regulate the gut microbiota composition and abundance. Consequences of the loss of these antimicrobial peptides and lysozymes are exacerbated during aging, and their loss contributes to increased microbiota abundance and shifted composition in old flies. This work shows that immune effectors, typically associated with resistance to pathogenic infections, also help shape the beneficial gut community, consistent with the idea that host-symbiont interactions use the same "language" typically associated with pathogenesis.
Topics: Animals; Antimicrobial Peptides; Bacteria; Drosophila melanogaster; Female; Gastrointestinal Microbiome; Host Microbial Interactions; Immune System; Muramidase; RNA, Ribosomal, 16S; Symbiosis
PubMed: 34253067
DOI: 10.1128/mBio.00824-21 -
Cell Aug 2021Environmental light cycles entrain circadian feeding behaviors in animals that produce rhythms in exposure to foodborne bacteria. Here, we show that the intestinal...
Environmental light cycles entrain circadian feeding behaviors in animals that produce rhythms in exposure to foodborne bacteria. Here, we show that the intestinal microbiota generates diurnal rhythms in innate immunity that synchronize with feeding rhythms to anticipate microbial exposure. Rhythmic expression of antimicrobial proteins was driven by daily rhythms in epithelial attachment by segmented filamentous bacteria (SFB), members of the mouse intestinal microbiota. Rhythmic SFB attachment was driven by the circadian clock through control of feeding rhythms. Mechanistically, rhythmic SFB attachment activated an immunological circuit involving group 3 innate lymphoid cells. This circuit triggered oscillations in epithelial STAT3 expression and activation that produced rhythmic antimicrobial protein expression and caused resistance to Salmonella Typhimurium infection to vary across the day-night cycle. Thus, host feeding rhythms synchronize with the microbiota to promote rhythms in intestinal innate immunity that anticipate exogenous microbial exposure.
Topics: Animals; Antimicrobial Cationic Peptides; Bacterial Adhesion; Cell Adhesion; Circadian Clocks; Circadian Rhythm; Epithelial Cells; Feeding Behavior; Gastrointestinal Microbiome; Immunity, Innate; Intestine, Small; Lymphocytes; Mice, Inbred C57BL; Muramidase; Pancreatitis-Associated Proteins; STAT3 Transcription Factor; Salmonella Infections, Animal; Signal Transduction; Mice
PubMed: 34324837
DOI: 10.1016/j.cell.2021.07.001 -
Immunity Aug 2020Paneth cells are the primary source of C-type lysozyme, a β-1,4-N-acetylmuramoylhydrolase that enzymatically processes bacterial cell walls. Paneth cells are normally...
Paneth cells are the primary source of C-type lysozyme, a β-1,4-N-acetylmuramoylhydrolase that enzymatically processes bacterial cell walls. Paneth cells are normally present in human cecum and ascending colon, but are rarely found in descending colon and rectum; Paneth cell metaplasia in this region and aberrant lysozyme production are hallmarks of inflammatory bowel disease (IBD) pathology. Here, we examined the impact of aberrant lysozyme production in colonic inflammation. Targeted disruption of Paneth cell lysozyme (Lyz1) protected mice from experimental colitis. Lyz1-deficiency diminished intestinal immune responses to bacterial molecular patterns and resulted in the expansion of lysozyme-sensitive mucolytic bacteria, including Ruminococcus gnavus, a Crohn's disease-associated pathobiont. Ectopic lysozyme production in colonic epithelium suppressed lysozyme-sensitive bacteria and exacerbated colitis. Transfer of R. gnavus into Lyz1 hosts elicited a type 2 immune response, causing epithelial reprograming and enhanced anti-colitogenic capacity. In contrast, in lysozyme-intact hosts, processed R. gnavus drove pro-inflammatory responses. Thus, Paneth cell lysozyme balances intestinal anti- and pro-inflammatory responses, with implications for IBD.
Topics: Animals; Clostridiales; Colitis, Ulcerative; Crohn Disease; Female; Gastrointestinal Microbiome; Goblet Cells; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Muramidase; Paneth Cells; STAT6 Transcription Factor
PubMed: 32814028
DOI: 10.1016/j.immuni.2020.07.010 -
Virchows Archiv : An International... Nov 2019Gastric cancer (GC) is frequently diagnosed and treated in advanced tumour stages with poor prognosis. Recent studies have identified isoform 2 of the tight junction...
Gastric cancer (GC) is frequently diagnosed and treated in advanced tumour stages with poor prognosis. Recent studies have identified isoform 2 of the tight junction protein claudin-18 (CLDN18.2) as a promising target in GC therapy. In this study, we aimed to outline the expression of CLDN18.2 and its correlation with clinico-pathological patient characteristics in a large and well-characterized cohort of GC patients. The expression of CLDN18.2 was studied in 481 GCs by immunohistochemistry on whole tissue sections. Immunostained GCs were evaluated using the histoscore (H-score) and subsequently divided into two groups: tumours showing any or no expression. CLDN18.2 expression was investigated for correlation with various clinico-pathological patient characteristics, including survival. CLDN18.2 expression was found in 203 GCs (42.2%). Of these tumours, 71 (14.8%) showed solely weak immunostaining. CLDN18.2 expression correlated with mucin phenotype, EBV status, the integrin αvβ5, the EpCAM extracellular domain EpEX, and lysozyme. We found no correlation with survival, Laurén phenotype, or any other clinico-pathological patient characteristic. In conclusion, we demonstrate frequently decreased expression of CLDN18.2 in a GC cohort of appropriate size. Correlating CLDN18.2 expression with clinico-pathological patient characteristics reveals new linkages to αvβ5, EpEX, and lysozyme, which may pave the way for further investigations regarding the role of tight junction proteins in GC progression. Though CLDN18.2 continues to pose an attractive target candidate, we conclude that a rather low overall expression rate challenges its significance in advanced GC therapy and indicates the need for further investigations across different populations.
Topics: Aged; Claudins; Cohort Studies; Epithelial Cell Adhesion Molecule; Female; Humans; Immunohistochemistry; Male; Mucins; Muramidase; Neoplasm Staging; Phenotype; Prognosis; Stomach Neoplasms; Tight Junctions; White People
PubMed: 31332522
DOI: 10.1007/s00428-019-02624-7 -
Molecules (Basel, Switzerland) Jan 2022The changes in the local and global dynamics of azide-labelled lysozyme compared with that of the wild type protein are quantitatively assessed for all alanine residues...
The changes in the local and global dynamics of azide-labelled lysozyme compared with that of the wild type protein are quantitatively assessed for all alanine residues along the polypeptide chain. Although attaching -N3 to alanine residues has been considered to be a minimally invasive change in the protein it is found that depending on the location of the alanine residue, the local and global changes in the dynamics differ. For Ala92, the change in the cross-correlated motions are minimal, whereas attaching -N3 to Ala90 leads to pronounced differences in the local and global correlations as quantified by the cross-correlation coefficients of the Cα atoms. We also demonstrate that the spectral region of the asymmetric azide stretch distinguishes between alanine attachment sites, whereas changes in the low frequency, far-infrared region are less characteristic.
Topics: Azides; Molecular Dynamics Simulation; Motion; Muramidase; Thermodynamics
PubMed: 35164105
DOI: 10.3390/molecules27030839 -
Angewandte Chemie (International Ed. in... Jul 2020We report the use of DNA origami nanostructures, functionalized with aptamers, as a vehicle for delivering the antibacterial enzyme lysozyme in a specific and efficient...
We report the use of DNA origami nanostructures, functionalized with aptamers, as a vehicle for delivering the antibacterial enzyme lysozyme in a specific and efficient manner. We test the system against Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) targets. We use direct stochastic optical reconstruction microscopy (dSTORM) and atomic force microscopy (AFM) to characterize the DNA origami nanostructures and structured illumination microscopy (SIM) to assess the binding of the origami to the bacteria. We show that treatment with lysozyme-functionalized origami slows bacterial growth more effectively than treatment with free lysozyme. Our study introduces DNA origami as a tool in the fight against antibiotic resistance, and our results demonstrate the specificity and efficiency of the nanostructure as a drug delivery vehicle.
Topics: Animals; Anti-Bacterial Agents; Aptamers, Nucleotide; Bacillus subtilis; COS Cells; Chlorocebus aethiops; DNA; Drug Carriers; Enzymes, Immobilized; Escherichia coli; Microbial Sensitivity Tests; Muramidase; Nanostructures; Nucleic Acid Conformation
PubMed: 32297692
DOI: 10.1002/anie.202002740 -
Molecules (Basel, Switzerland) Sep 2022Lysozymes are hydrolytic enzymes characterized by their ability to cleave the β-(1,4)-glycosidic bonds in peptidoglycan, a major structural component of the bacterial... (Review)
Review
Lysozymes are hydrolytic enzymes characterized by their ability to cleave the β-(1,4)-glycosidic bonds in peptidoglycan, a major structural component of the bacterial cell wall. This hydrolysis action compromises the integrity of the cell wall, causing the lysis of bacteria. For more than 80 years, its role of antibacterial defense in animals has been renowned, and it is also used as a preservative in foods and pharmaceuticals. In order to improve the antimicrobial efficacy of lysozyme, extensive research has been intended for its modifications. This manuscript reviews the natural antibiotic compound lysozyme with reference to its catalytic and non-catalytic mode of antibacterial action, lysozyme types, susceptibility and resistance of bacteria, modification of lysozyme molecules, and its applications in the food industry.
Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antiviral Agents; Bacteria; Food Industry; Muramidase; Peptidoglycan; Pharmaceutical Preparations
PubMed: 36234848
DOI: 10.3390/molecules27196305 -
Molecular Microbiology Mar 2021Gram-negative bacteria have evolved numerous pathways to secrete proteins across their complex cell envelopes. Here, we describe a protein secretion system that uses a... (Review)
Review
Gram-negative bacteria have evolved numerous pathways to secrete proteins across their complex cell envelopes. Here, we describe a protein secretion system that uses a holin membrane protein in tandem with a cell wall-editing enzyme to mediate the secretion of substrate proteins from the periplasm to the cell exterior. The identity of the cell wall-editing enzymes involved was found to vary across biological systems. For instance, the chitinase secretion pathway of Serratia marcescens uses an endopeptidase to facilitate secretion, whereas the secretion of Typhoid toxin in Salmonella enterica serovar Typhi relies on a muramidase. Various families of holins are also predicted to be involved. Genomic analysis indicates that this pathway is conserved and implicated in the secretion of hydrolytic enzymes and toxins for a range of bacteria. The pairing of holins from different families with various types of peptidoglycan hydrolases suggests that this secretion pathway evolved multiple times. We suggest that the complementary bodies of evidence presented is sufficient to propose that the pathway be named the Type 10 Secretion System (TXSS).
Topics: Amino Acid Sequence; Animals; Bacterial Proteins; Bacterial Secretion Systems; Cell Wall; Chitinases; Endopeptidases; Endotoxins; Gram-Negative Bacteria; Humans; Muramidase; N-Acetylmuramoyl-L-alanine Amidase; Peptidoglycan; Protein Transport; Salmonella typhi; Serratia marcescens; Viral Proteins
PubMed: 32885520
DOI: 10.1111/mmi.14599 -
Nature Aging Sep 2022The licensed drug rapamycin has potential to be repurposed for geroprotection. A key challenge is to avoid adverse side effects from continuous dosing. Here we show that...
The licensed drug rapamycin has potential to be repurposed for geroprotection. A key challenge is to avoid adverse side effects from continuous dosing. Here we show that geroprotective effects of chronic rapamycin treatment can be obtained with a brief pulse of the drug in early adulthood in female Drosophila and mice. In Drosophila, a brief, early rapamycin treatment of adults extended lifespan and attenuated age-related decline in the intestine to the same degree as lifelong dosing. Lasting memory of earlier treatment was mediated by elevated autophagy in intestinal enterocytes, accompanied by increased levels of intestinal LManV and lysozyme. Brief elevation of autophagy in early adulthood itself induced a long-term increase in autophagy. In mice, a 3-month, early treatment also induced a memory effect, with maintenance similar to chronic treatment, of lysozyme distribution, Man2B1 level in intestinal crypts, Paneth cell architecture and gut barrier function, even 6 months after rapamycin was withdrawn.
Topics: Animals; Female; Mice; Sirolimus; Muramidase; Paneth Cells; Drosophila; Autophagy
PubMed: 37118497
DOI: 10.1038/s43587-022-00278-w -
Cellular & Molecular Immunology Dec 2022Tissue-resident macrophages are derived from different precursor cells and display different phenotypes. Reconstitution of the tissue-resident macrophages of inflamed or...
Tissue-resident macrophages are derived from different precursor cells and display different phenotypes. Reconstitution of the tissue-resident macrophages of inflamed or damaged tissues in adults can be achieved by bone marrow-derived monocytes/macrophages. Using lysozyme (Lysm)-GFP-reporter mice, we found that alveolar macrophages (AMs), Kupffer cells, red pulp macrophages (RpMacs), and kidney-resident macrophages were Lysm-GFP, whereas all monocytes in the fetal liver, adult bone marrow, and blood were Lysm-GFP. Donor-derived Lysm-GFP resident macrophages gradually became Lysm-GFP in recipients and developed gene expression profiles characteristic of tissue-resident macrophages. Thus, Lysm may be used to distinguish newly formed and long-term surviving tissue-resident macrophages that were derived from bone marrow precursor cells in adult mice under pathological conditions. Furthermore, we found that Irf4 might be essential for resident macrophage differentiation in all tissues, while cytokine and receptor pathways, mTOR signaling pathways, and fatty acid metabolic processes predominantly regulated the differentiation of RpMacs, Kupffer cells, and kidney macrophages, respectively. Deficiencies in ST2, mechanistic target of rapamycin (mTOR) and fatty acid-binding protein 5 (FABP5) differentially impaired the differentiation of tissue-resident macrophages from bone marrow-derived monocytes/macrophages in the lungs, liver, and kidneys. These results indicate that a combination of shared and unique signaling pathways coordinately shape tissue-resident macrophage differentiation in various tissues.
Topics: Mice; Animals; Muramidase; Macrophages; Monocytes; Kupffer Cells; TOR Serine-Threonine Kinases
PubMed: 36348079
DOI: 10.1038/s41423-022-00936-4