[Mechanism of Hezi Decoction in reducing toxic side effects of Euphoriae Ebracteolata Radix on intestine based on proteomics]

Abstract

This paper aimed to explore the intestinal toxicity of Euphoriae Ebracteolata Radix(EER) before and after being processed with Mongolian medicine Hezi Decoction(HZD) and the toxicity-reducing mechanism of this processing method. The intestinal toxicity in rats treated with unprocessed EER and HZD-processed EER extracts via 95% ethanol was compared. The comparison was based on several indicators, including fecal volume, serum diamine oxidase(DAO) and D-lactate(D-LA) levels, the water content of various intestinal segments and their contents, and inflammatory factor levels in intestinal segments. Tandem mass tag(TMT) quantitative proteomics technology was employed to analyze the key proteins associated with changes in intestinal toxicity between unprocessed EER and HZD-processed EER. The results indicated that compared with the blank group, unprocessed EER significantly increased the fecal volume, serum DAO and D-LA levels, water content of the ileal segment and its contents, as well as the release levels of inflammatory factors, including tumor necrosis factor(TNF-α) and interleukin-1 beta(IL-1β) in the ileal segment of rats(P<0.05), indicating that EER can cause diarrhea, increase intestinal permeability, and induce intestinal inflammation. Compared with those in the unprocessed EER group, all indicators in the HZD-processed EER group were significantly reduced(P<0.05). The TMT quantitative proteomics analysis revealed that a total of 6 487 proteins were identified in the rat ileum tissue. Compared to the blank group, 182 proteins exhibited significant changes in the unprocessed EER group, while 907 proteins in the HZD-processed EER group showed significant changes. The intersection of the differential proteins between the two groups identified 38 common proteins. Among them, the protein levels of intestinal barrier tight junction protein claudin3, squalene monooxidase(Sqle), clusterin, Na~+/H~+ exchange regulatory cofactor NHE-RF3(Pdzk1), and Y+L amino acid transporter 1(Slc7a7) exhibited significant changes before and after processing, and these changes were closely related to intestinal barrier function. Compared with the blank group, the expression of claudin3, Pdzk1, and Slc7a7 in the raw product group was significantly down-regulated(P<0.05),while the expression of Sqle and clusterin was significantly up-regulated(P<0.05).Compared with the raw product group, the expression of claudin3, Pdzk1, and Slc7a7 in the processed product group of HZD was significantly up-regulated(P<0.05), while the expression of Sqle and clusterin was significantly down-regulated(P<0.05). Western blot was used to detect the expression level of claudin 3 in the ileum of rats in each group. The results show that compared to that in the blank group, the expression level of claudin 3 in the unprocessed EER group was significantly reduced(P<0.01); compared to that in the unprocessed EER group, the expression level of claudin 3 in the HZD-processed EER group was significantly increased(P<0.01). This finding aligned with the proteomic outcomes, indicating that claudin 3 protein levels could serve as a crucial indicator for intestinal damage caused by EER. In summary, HZD-processed EER can reduce EER's intestinal toxicity, and the primary mechanism for its alleviation of intestinal barrier damage is the regulation of the intestinal barrier tight junction protein claudin 3 and other intestinal-related proteins.

Keywords: Euphoriae Ebracteolata Radix; intestinal permeability; processing through Hezi Decoction; tandem mass tag(TMT) quantitative proteomics; tight junction protein.