Sodium Butyrate Inhibits Necroptosis by Regulating MLKL via E2F1 in Intestinal Epithelial Cells of Liver Cirrhosis.

Background and aims: Necroptosis is critical for regulating intestinal epithelial cells (IECs). Butyric acid (BA), produced during intestinal microbial metabolism, protects the intestinal epithelial barrier. However, whether necroptosis occurs in IECs during liver cirrhosis and whether sodium butyrate (NaB) can regulate necroptosis have not yet been reported. In this study, we aimed to investigate whether IECs undergo necroptosis in cirrhosis and whether NaB can regulate necroptosis and the related regulatory mechanisms.

Methods: Serum levels of RIPK3, MLKL, and Zonulin, as well as fecal BA levels, were measured and correlated in 48 patients with liver cirrhosis and 20 healthy controls. A rat model of liver cirrhosis was established, and NaB was administered. The expressions of MLKL, p-MLKL, and tight junction proteins were measured. We conducted an in vitro investigation of the effect of NaB on necroptosis in the HT29 cell line.

Results: Serum levels of RIPK3, MLKL, and Zonulin in the liver cirrhosis group were higher, while fecal BA levels were lower than those in the control group. Zonulin levels were positively correlated with RIPK3 and MLKL levels, while fecal BA levels were negatively correlated with serum MLKL levels, but not with RIPK3 levels. NaB reduced the mRNA and protein expression of MLKL but had no effect on RIPK1 and RIPK3 in vitro. Rescue experiments demonstrated that NaB inhibited necroptosis through E2F1-mediated regulation of MLKL.

Conclusions: NaB alleviates intestinal mucosal injury and reduces necroptosis in IECs in liver cirrhosis. It also inhibits the necroptosis of IECs and protects the intestinal barrier by reducing E2F1 expression and downregulating MLKL expression levels. These results can be employed to develop a novel strategy for treating complications arising from liver cirrhosis.