Aqueous extract of Paeoniae Radix Alba (Paeonia lactiflora Pall.) ameliorates DSS-induced colitis in mice by tunning the intestinal physical barrier, immune responses, and microbiota

Abstract

Ethnopharmacological relevance: Ulcerative colitis (UC) is a chronic non-specific intestinal inflammatory disease, the pathogenesis of which is strongly associated with the compromised intestinal barrier. Paeoniae Radix Alba (PRA), the root of Paeonia lactiflora Pall., is a well-known traditional Chinese medicine and an adaptogen used in Hozai, exhibiting appreciable anti-inflammatory and immunomodulatory activity. Nevertheless, the role and mechanism of PRA in UC have yet to be elucidated.

Aim of the study: This study was set out to examine the ameliorative effects of the aqueous extract of PRA (i.e., PRA dispensing granule, PRADG) on dextran sulfate sodium (DSS)-induced colitis.

Materials and methods: The chemical components of PRADG was analyzed by HPLC. Colitis model mice were induced by free access to water containing 2.5% DSS for 10 consecutive days, and concurrently, PRADG (0.1025 and 0.41 g/kg) or Salazosulfapyridine (SASP, 450 mg/kg) was given orally from day 1-10. Body weight, disease activity index (DAI), colon length, histologic scoring, and inflammatory response were assessed. Additionally, IL-23/IL-17 axis and tight junction (TJ) proteins, as well as gut microbiota were also investigated under the above-mentioned regimen.

Results: Eight main chemical constituents of CPT were revealed with HPLC analysis. Noticeably, PRADG could effectively lower body weight loss as well as DAI scores, alleviate colon shortening, and reduce the levels of proinflammatory cytokines in mice with colitis. Further exploration found that increment of TJ proteins expression (ZO-1, occludin and claudin-1) and inhibition of IL-23/IL-17 axis-modulated inflammation were observed in PRADG-treated mice. Additionally, the diversity of gut microbiota and the relative abundance of beneficial bacteria were increased following PRADG treatment.

Conclusions: PRADG could be sufficient to ameliorate colitis by regulating the intestinal physical barrier, immune responses, and gut microbiota in mice. Our findings highlight that PRADG might be a prospective remedy for UC.

Keywords: Aqueous extract of paeoniae radix alba; Gut microbiota; IL-23/IL-17 axis; Intestinal barrier; Tight junction; Ulcerative colitis.