The protective effects of Poria cocos-derived polysaccharide CMP33 against IBD in mice and its molecular mechanism.

Abstract

In this study, the protective effects of a carboxymethyl polysaccharide CMP33 from Poria cocos against inflammatory bowel disease (IBD) were investigated using TNBS-induced colitis in mice. The results showed that CMP33 markedly ameliorated the severity of colitis, including a 2-fold decrease in the mortality rate, a 50% decrease in disease activity index, and a 36%-44% decrease in macro- or microscopic histopathological score, compared with TNBS administration. Moreover, CMP33 decreased the levels of pro-inflammatory cytokines and increased the levels of anti-inflammatory cytokines in the colon tissue and serum of colitic mice. Using iTRAQ-coupled- nano-HPLC-MS/MS-based proteomics, the protein profiles after TNBS, high- or low-dose CMP33 and salazosulfapyridine (SASP) treatments were compared and many differentially expressed proteins were identified. Among them, 7 proteins (Hmgcs2, Fabp2, Hp, B4galnt2, B3gnt6, Sap and Ca1) were proposed to be the common targeting protein group (TPG) of CMP33 and drug SASP. Particularly, some targeting proteins were CMP33-dose-specific: high-dose-specific TPG (Mtco3, Gal-6, Mptx, S100 g and Hpx) and low-dose-specific TPG (Zg16, Hexb, Insl5, Cept1, Hspb6 and Ifi27l2b), suggesting the complex acting mechanism of CMP33. GC-TOF-MS-based metabolomics revealed that oleic acid and dihydrotestosterone could be the common targets of CMP33 and SASP. By integrative analysis of proteomics and metabolomics, key protein-metabolite pathways (PMP) were identified, PMP for high-dose: 2-hydroxybutyric acid - (GPT, GGH) - glutathione - ALB - testosterone - TTR - dihydrotestosterone; PMP for low-dose: (PYY, FABP2, HMGCS2) - oleic acid - TTR - dihydrotestosterone. In total, these results demonstrated the protective effects of CMP33 against IBD in mice through the potential TPG and PMP.