Intervention of inflammation associated with ankylosing spondylitis by triptolide promotes histone H3 Iys-27 trimethylation.

Objective: This study aims to explore the effects of Triptolide (TP) on the differentiation of Th17 cells in ankylosing spondylitis (AS).
Methods: Peripheral blood mononuclear cells (PBMCs) collected from 10 patients with active AS patients were exposed to TP, GSK-J4 or vehicle. T lymphocyte subsets were analyzed using flow cytometry. ELISA was used to assess the level of IL-17. Western blot analysis and quantitative RT-PCR were used to measure the mRNA and protein levels of RORγt, JMJD3, EZH2, JAK2 and STAT3 in the JAK2/STAT3 signaling pathway.
Results: We observed a tendency toward a greater percentage of IL-17-positive CD4+ T cells in peripheral blood mononuclear cells (PBMCs) from patients with active AS than in those from healthy controls. Triptolide (TP) and GSK-J4 significantly reduced IL-17 expression. In cultured PBMCs from patients with active AS, 24 h of treatment with TP or GSK-J4 decreased the expression of RORγt ( p  < 0.05), JAK2 and STAT3 (JAK2: p  < 0.05; STAT3: p  < 0.05). Furthermore, both triptolide and GSK-J4 increased the level of histone 3 with Lys 27 trimethylation (H3K27me3) in patient-derived PBMCs. H3K27me3 enrichment was detected at the promoters of the RORc, STAT3 and IL-17 genes. Consistent with this finding, triptolide upregulated the EZH2 gene and downregulated the JMJD3 gene.
Conclusion: Triptolide inhibits Th17 cell differentiation via H3K27me3 upregulation and orchestrates changes in histone-modifying enzymes, including JMJD3 and EZH2. These findings support the clinical efficacy of triptolide for AS and may provide clues for identifying molecular targets for the development of novel treatments.