EBioMedicine (Oct 2019)

Mucin O-glycans facilitate symbiosynthesis to maintain gut immune homeostasisResearch in context

  • Takahiro Yamada,
  • Shingo Hino,
  • Hideki Iijima,
  • Tomomi Genda,
  • Ryo Aoki,
  • Ryuji Nagata,
  • Kyu-Ho Han,
  • Masato Hirota,
  • Yusuke Kinashi,
  • Hiroyuki Oguchi,
  • Wataru Suda,
  • Yukihiro Furusawa,
  • Yumiko Fujimura,
  • Jun Kunisawa,
  • Masahira Hattori,
  • Michihiro Fukushima,
  • Tatsuya Morita,
  • Koji Hase

Journal volume & issue
Vol. 48
pp. 513 – 525

Abstract

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Background: The dysbiosis of gut microbiota has been implicated in the pathogenesis of inflammatory bowel diseases; however, the underlying mechanisms have not yet been elucidated. Heavily glycosylated mucin establishes a first-line barrier against pathogens and serves as a niche for microbial growth. Methods: To elucidate relationships among dysbiosis, abnormal mucin utilisation, and microbial metabolic dysfunction, we analysed short-chain fatty acids (SCFAs) and mucin components in stool samples of 40 healthy subjects, 49 ulcerative colitis (UC) patients, and 44 Crohn's disease (CD) patients from Japan. Findings: Levels of n-butyrate were significantly lower in stools of both CD and UC patients than in stools of healthy subjects. Correlation analysis identified seven bacterial species positively correlated with n-butyrate levels; the major n-butyrate producer, Faecalibacterium prausnitzii, was particularly underrepresented in CD patients, but not in UC patients. In UC patients, there were inverse correlations between mucin O-glycan levels and the production of SCFAs, such as n-butyrate, suggesting that mucin O-glycans serve as an endogenous fermentation substrate for n-butyrate production. Indeed, mucin-fed rodents exhibited enhanced n-butyrate production, leading to the expansion of RORgt+Treg cells and IgA-producing cells in colonic lamina propria. Microbial utilisation of mucin-associated O-glycans was significantly reduced in n-butyrate-deficient UC patients. Interpretation: Mucin O-glycans facilitate symbiosynthesis of n-butyrate by gut microbiota. Abnormal mucin utilisation may lead to reduced n-butyrate production in UC patients. Fund: Japan Society for the Promotion of Science, Health Labour Sciences Research Grant, AMED-Crest, AMED, Yakult Foundation, Keio Gijuku Academic Development Funds, The Aashi Grass Foundation, and The Canon Foundation. Keywords: Microbiota, Butyrate, Mucin, Inflammatory bowel disease