Gut microbiota is the consortium of numerous commensal bacteria resid-43nisms of host-gut microbiota interactions.ing in our intestines. Our lab has been studying the molecular mecha-The host does not freely allow the residence of those microorganisms. The intestinal immune system can somehow sense the bacteria in the gut lumen and try to contain them. To this end, M cells, a specialized intestinal epithelial cell subset for recognition and uptake of luminal bacteria to initiate intestinal immune responses, have evolved. Our lab has elucidated the molecular mecha-nisms of M-cell differentiation and function.IgA is a major class of immunoglobulins produced and secreted in mucosal tissues including the intestine. Last year, we have published a paper showing that the amount and specificity of IgA toward commensal bacteria is regulated by acetate and the type of bacteria present in the intestine.Host-gut microbiota interactions deeply impact the physiology and pathol-ogy of the host. We have been studying this process by applying an integrated omics approach, where exhaustive analyses at different layers of organismal activities are combined, including (meta) genomics, epigenomics, (meta) tran-scriptomics and metabolomics.The bacterial composition of the gut lumen and mucosa are distinct and the mucosa-associated bacteria are thought to more deeply impact the host patho-physiology. In the past year, we have evaluated the potential use of colonic lavage samples for mucosal microbiota analysis in humans. Among the different types of colonic mucosal samples collected from healthy volunteers, the lavage samples contained a higher amount of bacterial DNA and were less contaminated with host DNA compared to mucosal brushing and biopsy. Furthermore, differences in mucosal microbes were detectable in lavage samples from non-smokers and smokers. Therefore, the colonic lavage method could promote research on the human mucosal microbiota, especially in gastrointestinal disorders.Figure: Heatmap of log 10 linear discriminant analysis (LDA) scores of taxa detected in biopsy samples as discriminants between non-smokers and smokersThe lavage samples showed an identical pattern of LDA scores to biopsy samples, although they were only partially significant. *p < 0.05; Kruskal-Wallis rank sum test. [Taken from Figure 3b of Miyauchi E et al. Sci Rep 12: 1758 (2022)].Recent Major PublicationsMiyauchi E, Taida T, Kawasumi M, Ohkusa T, Sato N, Ohno H. Analysis of colonic mucosa- mucosa-associated microbiota using endoscopically collected lavage. Sci Rep 12, 1758 (2022)Takeuchi T, Miyauchi E, Kanaya T, Kato T, Nakanishi Y, Watanabe T, Kitami T, Taida T, Sasaki T, Negishi H, Shima-moto S, Matsuyama A, Kimura I, Williams IR, Ohara O, Ohno H. Acetate differentially regulates IgA reactivity to commensal bacteria. Nature 595, 560-564 (2021)Takeuchi T, Ohno H. Reciprocal regulation of IgA and the gut microbiota: a key mutualism in the intestine. Int Immunol 33, 781-786 (2021)Invited presentationsOhno H. “Mucosal immunity and microbiota” The 49th Annual Meeting of the Japanese Society of Clinical Im-munology (Tokyo, Japan) October 2021Ohno H. “Gut microbiota, immunity, and autoimmune diseases” Educational Lecture, The 83rd Annual Meeting of the Japanese Society of Hematology (Tokyo, Japan/Online) September 2021Ohno H. “Gut Microbiota and Autoimmune Diseases – Type 1 Diabetes and Multiple Sclerosis -” Educational Lecture, The Asian Pacific Association for the Study of the Liver Single Topic Conference, Molecular and Cell Biology of the Liver: Recent Evolution to Clinical Applica-tion (Osaka, Japan/Online) September 2021Ohno H. “Gut Microbiota and Autoimmune Diseases” Symposium 4: Mucosal immunology, Dysbiosis, The 27th International Symposium on Molecular Cell Biology of Macrophages (Osaka, Japan/Online) June 2021Ohno H. “The role of small intestinal microbes for central nervous system inflammation” International Conference on Beneficial Microbes 2021 (Rostov-on-Don, Russia/Online) June 2021Laboratory for Intestinal EcosystemTeam Leader: Hiroshi Ohno
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