[Relationship between the methylation status of STAT3 promoter DNA in peripheral blood CD4+ T cells from patients after allo-HSCT and aGVHD].

OBJECTIVE: To study the relationship between acute graft versus host disease (aGVHD) and the methylation status of the STAT3 promoter in peripheral blood CD4+ T cells from patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT).
 Methods: We collected 40 patients who underwent allo-HSCT from HLA-identical sibling donors. Serum IL-10, TGF-β1, IL-17A and IL-17F levels were detected by ELISA. Foxp3 cytotoxic T-lymphocyte-associated protein 4 (CTLA4), IL-10, TGF-β1, RORγt, IL-17A and IL-17F mRNA levels in CD4+ T cells were measured by real-time PCR. STAT3 expression levels were detected by real-time PCR and Western blot, and promoter DNA methylation was analyzed by bisulfite sequencing PCR (BSP).
 Results: IL-10 and TGF-β1 levels were significantly down-regulated, while IL-17A and IL-17F levels were significantly up-regulated in patients with aGVHD compared with patients without aGVHD. Foxp3, CTLA4, IL-10, TGF-β1 mRNA levels were significantly down-regulated, while RORγt, IL-17A, IL-17F mRNA levels were significantly up-regulated in patients with aGVHD compared with patients without aGVHD. STAT3 expression was increased, while STAT3 promoter DNA was hypomethylated in patients with aGVHD compared with those without aGVHD. The STAT3 mRNA level was negatively correlated with STAT3 promoter DNA methylation.
 Conclusion: The imbalance of Treg/Th17 in CD4+ T cells from patients after allo-HSCT is a key factor for triggering aGVHD, and the DNA hypomethylation of STAT3 promoter could promote its expression in CD4+ T cells and contribute to the imbalance.