Orally administered aqueous extract of Inonotus obliquus ameliorates acute inflammation in dextran sulfate sodium (DSS)-induced colitis in mice

Abstract

Ethnopharmacological relevance: Chaga mushroom (Inonotus obliquus) has been used in folk medicine to treat several disorders through its various biological functions. I. obliquus is claimed to produce general immune-potentiating and strengthening, antiinflammatory, and antitumor properties, but its effects on intestinal inflammation (ulcerative colitis) are clearly not understood.

Aim of the study: To determine the effects and mode of action of an aqueous extract of I. obliquus (IOAE) on experimental colitis in mice induced by dextran sulfate sodium (DSS).

Materials and methods: Female 5-week-C57BL/6 mice were randomized into groups differing in treatment conditions (prevention and treatment) and doses of IOAE (50 and 100mg/kg body weight). Mice were exposed to DSS (2%) in their drinking water over 7 day to induce acute intestinal inflammation. In colon tissues, we evaluated histological changes by hematoxylin and eosin staining, levels of iNOS by immuno-histochemical staining, and neutrophil influx by myeloperoxidase assay. mRNA expression of pro-inflammatory mediators TNF-α, IL-1β, IL-6, and IFN-γ was determined by RT-PCR.

Results: Histological examinations indicated that IOAE suppressed edema, mucosal damage, and the loss of crypts induced by DSS. IOAE markedly attenuated DSS-induced iNOS levels and myeloperoxidase accumulation in colon tissues, demonstrating its suppressive effect on infiltration of immune cells. In addition, IOAE significantly inhibited mRNA expression of pro-inflammatory cytokines induced by DSS in colon tissues.

Conclusion: Our results suggest anti-inflammatory effect of IOAE at colorectal sites due to down-regulation of the expression of inflammatory mediators. Suppression of TNF-α and iNOS together with IL-1β by IOAE denotes that it might be a useful supplement in the setting of inflammatory bowel disease.