Ulcerative colitis has become a health burden worldwide. Dendrobium officinale polysaccharide (DOP) has been reported to be a promising therapy. Although its effect
on microbiota regulation was previously demonstrated, the role of gut microbiota in
DOP’s activity remains unclear. This research aims to verify its beneficial effect
on the DSS-induced colitis mice model and explore the underlying mechanism. The results
showed that DOP reduced the disease activity index, ameliorated colon shortening and
colonic damage, suppressed colonic inflammation, and enhanced the intestinal tight
junction in DSS-treated colitis mice. In addition, the result of 16S rRNA sequencing
and metabolite analysis revealed that DOP altered the structure of gut microbiota
and increased the production of short-chain fatty acids (SCFAs) in colitis mice. Interestingly,
we found DOP undegraded in vancomycin-treated mice but not neomycin-treated mice.
Moreover, the depletion of vancomycin-sensitive bacteria also blocked the anti-colitis
effect of DOP in mice. By comparing the different abundant bacteria between colitis
mice and DOP-treated mice, the gram- positive bacteria, genus Allobaculum, was identified as the key player for DOP’s activity. Furthermore, the enzymatic
product mannan endo-1,4-beta-mannosidase that breaks down DOP was positively correlated
to the relative abundance of Allobaculum. Collectively, DOP alleviated DSS-induced colitis in mice by Allobaculum-mediated degradation to yield SCFAs ([Fig. 1]).
Fig. 1 DOP reduced the disease activity index, ameliorated colon shortening and colonic
damage, suppressed colonic inflammation, and enhanced the intestinal tight junction
in DSS-treated colitis mice, which was mediated by production of microbiota-derived
SCFAs.
