Glycan Sequence‐Dependent Nod2 Activation Investigated by Using a Chemically Synthesized Bacterial Peptidoglycan Fragment Library

Nucleotide oligomerization domain‐containing protein 2 (Nod2), an innate immune receptor, recognizes bacterial cell‐wall peptidoglycan (PGN), the minimum ligand of which is muramyl dipeptide (MDP). Enzymatic digestion of PGN appears to be important for Nod2 recognition. PGN is degraded by muramidase or glucosamidase through a process that produces two types of glycan sequence; glycans containing GlcNAcβ(1→4)MurNAc or MurNAcβ(1→4)GlcNAc. In this report, a range of disaccharide or tetrasaccharide fragments of each sequence were chemically synthesized, and their activities in stimulating human Nod2 (hNod2) were investigated. The results reveal that hNod2 recognitions is dependent on the glycan sequence, as demonstrated by comparing the activities of glycans with the same peptide moieties. (MurNAcβ(1→4)GlcNAc) 2 ‐containing structures exhibited stronger activity than those containing (GlcNAcβ(1→4)MurNAc) 2 . The results suggest that differences in the enzymatic degradation process affect the host's immunomodulation process. To Nod off or on? Di‐ or tetrasaccharide fragments of muramidase and glucosamidase were chemically synthesized, and their abilities to stimulate human Nod2 were investigated. The results reveal that hNod2 recognition is glycan sequence‐dependent, and suggest that the peptidoglycan degradation process affects the host's immunomodulation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96737/1/cbic_201200655_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/96737/2/482_ftp.pd

Impact of dietary manganese on experimental colitis in mice

Diet plays a significant role in the pathogenesis of inflammatory bowel disease (IBD). A recent epidemiological study has shown an inverse relationship between nutritional manganese (Mn) status and IBD patients. Mn is an essential micronutrient required for normal cell function and physiological processes. To date, the roles of Mn in intestinal homeostasis remain unknown and the contribution of Mn to IBD has yet to be explored. Here, we provide evidence that Mn is critical for the maintenance of the intestinal barrier and that Mn deficiency exacerbates dextran sulfate sodium (DSS)â induced colitis in mice. Specifically, when treated with DSS, Mnâ deficient mice showed increased morbidity, weight loss, and colon injury, with a concomitant increase in inflammatory cytokine levels and oxidative and DNA damage. Even without DSS treatment, dietary Mn deficiency alone increased intestinal permeability by impairing intestinal tight junctions. In contrast, mice fed a Mnâ supplemented diet showed slightly increased tolerance to DSSâ induced experimental colitis, as judged by the colon length. Despite the wellâ appreciated roles of intestinal microbiota in driving inflammation in IBD, the gut microbiome composition was not altered by changes in dietary Mn. We conclude that Mn is necessary for proper maintenance of the intestinal barrier and provides protection against DSSâ induced colon injury.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/1/fsb220201_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/2/fsb220201-sup-0002-TableS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/3/fsb220201-sup-0005-TableS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/4/fsb220201.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/5/fsb220201-sup-0003-TableS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/6/fsb220201-sup-0004-TableS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154377/7/fsb220201-sup-0001-TableS1-S2.pd

IL-22 controls iron-dependent nutritional immunity against systemic bacterial infections

This publication hasn't any creative commons license associated.This publication has a exclusive licensee of the American Association for the Advancement of Science.The deposited article contains attached the supplementary materials.Host immunity limits iron availability to pathogenic bacteria, but whether immunity limits pathogenic bacteria from accessing host heme, the major source of iron in the body, remains unclear. Using Citrobacter rodentium, a mouse enteric pathogen and Escherichia coli, a major cause of sepsis in humans as models, we find that interleukin-22, a cytokine best known for its ability to promote epithelial barrier function, also suppresses the systemic growth of bacteria by limiting iron availability to the pathogen. Using an unbiased proteomic approach to understand the mechanistic basis of IL-22 dependent iron retention in the host, we have identified that IL-22 induces the production of the plasma hemoglobin scavenger haptoglobin and heme scavenger hemopexin. Moreover, the anti-microbial effect of IL-22 depends on the induction of hemopexin expression, while haptogloblin is dispensable. Impaired pathogen clearance in infected Il22(-/-) mice was restored by administration and hemopexin-deficient mice had increased pathogen loads after infection. These studies reveal a previously unrecognized host defense mechanism regulated by IL-22 that relies on the induction of hemopexin to limit heme availability to bacteria leading to suppression of bacterial growth during systemic infections.Japan Society for the Promotion of Science fellowship; Kanae Foundation for the Promotion of Medical Science; Mishima Kaiun Memorial Foundation; Consejo Nacional de Ciencia y Tecnología of Mexico post-doctoral fellowship: (454848); NIH grants: (DK091191, DK095782); Fundação Calouste Gulbenkian;info:eu-repo/semantics/publishedVersio

Mechanism of ASC-mediated apoptosis: Bid-dependent apoptosis in type II cells

金沢大学がん研究所がん病態制御Apoptosis-associated speck-like protein containing a CARD (ASC) is an adaptor molecule that mediates apoptotic and inflammatory signals, and implicated in tumor suppression. However, the mechanism of ASC-mediated apoptosis has not been well elucidated. Here, we investigated the molecular mechanisms of ASC-mediated apoptosis in several cell lines using a caspase recruitment domain 12-Nod2 chimeric protein that transduces the signal from muramyl dipeptide into ASC-mediated apoptosis. Experiments using dominant-negative mutants, small-interfering RNAs and peptide inhibitors for caspases indicated that caspase-8 was generally required for ASC-mediated apoptosis, whereas a requirement for caspase-9 depended on the cell type. In addition, caspase-like apoptosis-regulatory protein (CLARP)/Fas-like inhibitor protein, a natural caspase-8 inhibitor, suppressed ASC-mediated apoptosis, and Clarp-/- mouse embryonic fibroblasts were highly sensitive to ASC-mediated apoptosis. Bax-deficient HCT116 cells were resistant to ASC-mediated apoptosis as reported previously, although we failed to observe colocalization of ASC and Bax in cells. Like Fas-ligand-induced apoptosis, the ASC-mediated apoptosis was inhibited by Bcl-2 and/or Bcl-XL in type-II but not type-I cell lines. Bid was cleaved upon ASC activation, and suppression of endogenous Bid expression using small-interfering RNAs in type-II cells reduced the ASC-mediated apoptosis. These results indicate that ASC, like death receptors, mediates two types of apoptosis depending on the cell type, in a manner involving caspase-8. © 2007 Nature Publishing Group All rights reserved

RICK/Rip2/CARDIAK mediates signalling for receptors of the innate and adaptive immune systems

The immune system consists of two evolutionarily different but closely related responses, innate immunity and adaptive immunity. Each of these responses has characteristic receptors-Toll-like receptors (TLRs) for innate immunity and antigen-specific receptors for adaptive immunity. Here we show that the caspase recruitment domain (CARD)-containing serine/threonine kinase Rip2 (also known as RICK, CARDIAK, CCK and Ripk2)(1-4) transduces signals from receptors of both immune responses. Rip2 was recruited to TLR2 signalling complexes after ligand stimulation. Moreover, cytokine production in Rip2-deficient cells was reduced on stimulation of TLRs with lipopolysaccharide, peptidoglycan and double-stranded RNA, but not with bacterial DNA, indicating that Rip2 is downstream of TLR2/3/4 but not TLR9. Rip2-deficient cells were also hyporesponsive to signalling through interleukin (IL)-1 and IL-18 receptors, and deficient for signalling through Nod proteins-molecules also implicated in the innate immune response. Furthermore, Rip2-deficient T cells showed severely reduced NF-kappaB activation, IL-2 production and proliferation on T-cell-receptor (TCR) engagement, and impaired differentiation to T-helper subtype 1 (T(H)1) cells, indicating that Rip2 is required for optimal TCR signalling and T-cell differentiation. Rip2 is therefore a signal transducer and integrator of signals for both the innate and adaptive immune systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62842/1/416194a.pd

Nod1 acts as an intracellular receptor to stimulate chemokine production and neutrophil recruitment in vivo

Nod1 is a member of family of intracellular proteins that mediate host recognition of bacterial peptidoglycan. To characterize immune responses mediated by Nod1, synthetic ligand compounds possessing enhanced ability to stimulate Nod1 were developed to study the function of Nod1. Stimulation of epithelial cells with Nod1 stimulatory molecules induced chemokines and other proinflammatory molecules that are important for innate immune responses and recruitment of acute inflammatory cells. Administration of Nod1 ligands into mice induced chemokines and recruitment of acute inflammatory cells, an activity that was abolished in Nod1-null mice. Microarray analysis revealed that Nod1 stimulation induces a restricted number of genes in intestinal epithelial cells compared with that induced by tumor necrosis factor (TNF) α. Nod1 stimulation did not induce TNFα, interleukin 12, and interferon γ, suggesting that the primary role of Nod1 is to induce the recruitment of immune cells. These results indicate that Nod1 functions as a pathogen recognition molecule to induce expression of molecules involved in the early stages of the innate immune response

Neonatal skin dysbiosis to infantile atopic dermatitis: Mitigating effects of skin care

Aoyama R., Nakagawa S., Ichikawa Y., et al. Neonatal skin dysbiosis to infantile atopic dermatitis: Mitigating effects of skin care. Allergy: European Journal of Allergy and Clinical Immunology , (2024); https://doi.org/10.1111/all.16095

A frameshift mutation in NOD2 associated with susceptibility to Crohn's disease

Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract, which is thought to result from the effect of environmental factors in a genetically predisposed host. A gene location in the pericentromeric region of chromosome 16, IBD1, that contributes to susceptibility to Crohn's disease has been established through multiple linkage studies(1-6), but the specific gene(s) has not been identified. NOD2, a gene that encodes a protein with homology to plant disease resistance gene products is located in the peak region of linkage on chromosome 16 (ref. 7). Here we show, by using the transmission disequilibium test and case-control analysis, that a frameshift mutation caused by a cytosine insertion, 3020insC, which is expected to encode a truncated NOD2 protein, is associated with Crohn's disease. Wild-type NOD2 activates nuclear factor NF-kappaB, making it responsive to bacterial lipopolysaccharides; however, this induction was deficient in mutant NOD2. These results implicate NOD2 in susceptibility to Crohn's disease, and suggest a link between an innate immune response to bacterial components and development of disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62856/1/411603a0.pd

Microbial Metabolite Signaling Is Required for Systemic Iron Homeostasis

45 Pág.Iron is a central micronutrient needed by all living organisms. Competition for iron in the intestinal tract is essential for the maintenance of indigenous microbial populations and for host health. How symbiotic relationships between hosts and native microbes persist during times of iron limitation is unclear. Here, we demonstrate that indigenous bacteria possess an iron-dependent mechanism that inhibits host iron transport and storage. Using a high-throughput screen of microbial metabolites, we found that gut microbiota produce metabolites that suppress hypoxia-inducible factor 2α (HIF-2α) a master transcription factor of intestinal iron absorption and increase the iron-storage protein ferritin, resulting in decreased intestinal iron absorption by the host. We identified 1,3-diaminopropane (DAP) and reuterin as inhibitors of HIF-2α via inhibition of heterodimerization. DAP and reuterin effectively ameliorated systemic iron overload. This work provides evidence of intestine-microbiota metabolic crosstalk that is essential for systemic iron homeostasis.This work was supported by the NIH, United States (grants CA148828 and DK095201 to Y.M.S. and F31 DK11655 to A.J.S.); the University of Michigan Center for Gastrointestinal Research, United States (DK034933); a pilot grant from the University of Michigan, United States-GI Spore (CA130810 to Y.M.S.); the University of Michigan, United States Microbiome Explorer Program, NIAID, United States Novel Alternative Model Systems for Enteric Diseases (NAMSED) consortium (U19AI116482 to M.K.S., J.R.S. and V.B.Y.); NIAID, United States (U01AI124255 to M.K.S. and V.B.Y.) Crohn’s & Colitis Foundation, United States Senior Research Award (410234) to N.I.; Clinical and Translational Science Award (CTSA) from The Michigan Institute for Clinical & Health Research (MICHR), United States (UL1TR000433) to D.R.H.; The Pennsylvania Department of Health, United States using Tobacco CURE grant to A.D.P.; and the Spanish Ministry of Science Innovation and Universities, Spain (RTA2017-00002-00-00 to J.L.A.).Peer reviewe