Increased miR-155 expression in peripheral blood mononuclear cells of primary immune thrombocytopenia patients was correlated with serum cytokine profiles.

We investigated the possible pathogenic role of a microRNA (miR-155) in primary immune thrombocytopenia (ITP). We used quantitative real-time PCR to determine the relative expression of miR-155 and SOCS1 (suppressor of cytokine signaling) mRNA in peripheral blood mononuclear cells (PBMCs) from 28 ITP patients and 28 healthy controls. Cytokine plasma levels were determined by ELISA. Possible associations between miR-155 levels and serum cytokine concentrations were assessed using Spearman or Pearson correlation analysis. Seven naive ITP patients were followed and the effects of medical treatment on miR-155 levels were assessed. Compared to healthy controls, ITP patients had increased miR-155 and decreased SOCS1 mRNA levels. ITP patients also had increased plasma IL-17A and decreased IL-4, IL-10 and TGF-β1 levels. miR-155 levels were negatively correlated with platelet counts, SOCS1 mRNA levels, and the plasma levels of IL-4, IL-10 and TGF-β1, but positively correlated with plasma IL-17A levels. Medical treatment for ITP decreased miR-155 levels. Thus, our results suggest that miR-155 might be involved in the pathogenesis of ITP by regulating cytokine profiles, which may be mediated by miR-155 targeting SOCS1.