siRNA-mediated knockdown of T-bet and RORγt contributes to decreased inflammation in pre-eclampsia

Abstract

Abnormal immune response resulting from disordered T helper (Th)1/Th2 and Th17/regulatory T cells (Treg) cytokine expression has been demonstrated to serve an important role in the pathogenesis of preeclampsia (PE). However, the role of transcription factors regulating Th cell differentiation contributing to PE remain unclear. To determine whether a decrease in the expression of the T cell lineage transcription factor T-bet can restore immune balance and alleviate the systemic inflammatory response present in PE, 30 patients diagnosed with PE were assessed and compared with healthy pregnant controls. The expression of the transcription factors T-bet and retinoic acid receptor-related orphan receptor (ROR)γt were increased in the peripheral blood mononuclear cells of PE patients compared with controls, consistent with the presence of abnormally high T-bet:GATA3 and RORγt:forkhead box (FOX) P3 ratios. The present study additionally identified a high-efficiency, specific small interfering (si)RNA that can downregulate RORγt and T-bet mRNA levels and inhibit protein expression. This effective siRNA was transfected into activated CD4+ T cells derived from patients with PE to observe the changes to transcription factor expression and attempt to elucidate the regulatory mechanism of T cell subsets. It was identified that knockdown of RORγt induced increased expression of FOXP3 and that the ratios of RORγt:FOXP3 and interleukin (IL)-17A:IL-10 were subsequently decreased. The results suggested that siRNA-mediated knockdown of T-bet regulated the immune balance of Th17/Tregs via changes to RORγt and FOXP3. When siRNA against RORγt and T-bet were used in combination, a stronger ability to regulate immune balance was observed. These results imply that Th1- and Th17-type immunity is dominant in PE and that the siRNA-mediated knockdown of certain Th1 and Th17 cell transcription factors may be an effective therapeutic target for promoting immune balance in CD4+ T cell subgroups and ameliorating local and generalized inflammation in PE.