Ulcerative colitis is a
gastrointestinal disorder intricately associated with intestinal
dysbiosis, but effective treatments are currently limited.
Indigo naturalis, a
traditional Chinese medicine derived from
indigo plants, has been widely used in the treatment of
ulcerative colitis. However, the specific mechanisms have not yet been identified. Accordingly, in this study, we evaluated the effects and mechanisms of
indigo naturalis on
dextran sulfate sodium (DSS)-induced
colitis in rats. Our results showed that
indigo naturalis potently alleviated DSS-induced
colitis in rats, and reversed DSS-induced intestinal
dysbiosis using bacterial
16S rRNA amplicon sequencing. The protective effects of
indigo naturalis were gut microbiota dependent, as demonstrated by
antibiotic treatments and
fecal microbiota transplantation. Depletion of the gut microbiota through a combination of
antibiotic treatments blocked the anti-inflammatory effect of
indigo naturalis on the DSS-induced
colitis, and the recipients of the gut microbiota from
indigo naturalis-treated rats displayed a significantly attenuated intestinal
inflammation, which was actively responsive to therapeutic interventions with
indigo naturalis. Notably, supplement with
indigo naturalis greatly increased the levels of feces
butyrate, which was positively correlated with the relative abundances of Ruminococcus_1 and Butyricicoccus. We further showed that
indigo naturalis-dependent attenuation of
colitis was associated with elevated expression of
short-chain fatty acid-associated receptors GPR41 and GPR43. Collectively, these results suggested that
indigo naturalis alleviates DSS-induced
colitis in rats through a mechanism of the microbiota-
butyrate axis, particularly alterations in Ruminococcus_1 and Butyricicoccus abundances, and target-specific microbial species may have unique therapeutic promise for
ulcerative colitis.