Homocysteine Promotes Intestinal Inflammation in Colitis Mice Through the PGE2/STAT3 Signaling Pathway.

Background: Our previous study indicated that Hcy exacerbated DSS-induced colitis by facilitating the differentiation of intestinal T helper cell 17 (Th17), but the precise mechanism remains unidentified. Therefore, our current research aims to elucidate the signaling pathway through which Hcy promotes the differentiation of Th17 cells.

Methods: BALb/c mice were randomly assigned into six groups. The model of mice colitis was induced using 3% DSS, while the model of Hyperhomocysteinemia was induced using 1.7% methionine. The concentrations of Hcy and prostaglandin E2 (PGE2) were measured using enzyme-linked immunosorbent assay (ELISA). The protein expressions of cytosolic phospholipase A2 (cPLA2), phosphorylated-cPLA2 (p-cPLA2), cyclooxygenase 2 (COX2), cyclic adenosine monophosphate (cAMP), signal transducer and activator of transcription 3 (STAT3), phosphorylated-STAT3 (p-STAT3), interleukin-17A (IL-17A), and retinoid-related orphan nuclear receptor-γt (RORγt) were assessed using western blot analysis.

Results: Compared to the DSS + HHcy group, the addition of the COX inhibitor did not significantly alter the protein expression of p-PLA2/PLA2, but led to significant decreases in serum PGE2 concentration, cAMP, and p-STAT3/STAT3 protein expression. The protein expressions of p-PLA2/PLA2, COX2, and cAMP upstream of STAT3 inhibitor addition did not exhibit significant changes. However, PGE2 concentration and p-STAT3/STAT3 protein expression were notably reduced. After the COX inhibitor and STAT3 inhibitor added, the protein expression of IL-17A and RORγt and the levels of IL-17A and IL-23R in CD4 T cells were significantly reduced.

Conclusion: HHcy aggravated DSS-induced colitis by promoting the differentiation and proliferation of Th17 cells through the PGE2 / STAT3 signaling pathway.