Increased Expression of TLR2 and TLR4 in Mononuclear Cells in Patient with Immune Thrombocytopenic Purpura.

Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by platelet destruction resulting from autoantibodies against self-antigens and T-cell mediated cytotoxicity. Toll-like receptors (TLRs) are pattern recognition receptors important in mediating the immune response and their activation can lead to production of cytokines. Recent data suggest that TLR2 and TLR4 are crucial for the production of inflammatory cytokines and play central role in autoimmune diseases, yet little is known about their roles in ITP. Here we examined the gene expressions of TLR2 and TLR4 in ITP patients. We hypothesize that significant differences will exist between pre-treatment and post-treatment in ITP patients with similar changes reflected in the plasma concentration of cytokines. Total RNA was extracted from mononuclear cells obtained from 12 ITP patients and 15 healthy subjects. TLR2 and TLR4 mRNA expression levels were analyzed using a quantitative real-time PCR method and their protein expressions were validated by western blot. Plasma concentrations of cytokines IL-2, IFN-γ and TNF-α were measured by ELISA. Correlation analyses were carried out between the mRNA expression levels of TLR2 or TLR4 and the plasma levels of IL-2, IFN-γ and TNF-α. The gene expression of TLR2 and TLR4 were significantly increased in ITP patients comparing to healthy control group (p < 0.05 and p < 0.01, respectively). In addition their mRNA expression levels were decreased back into normal range after remission in 8 patients (p > 0.05, compared to healthy control group). Significantly positive correlations were found between the TLR2 mRNA expression level and the plasma concentration of IFN-γ or TNF-α (R = 0.75, p < 0.05; R = 0.83, p < 0.05, respectively). Changes in the gene expression of TLR4 and in the plasma concentration of IFN-γ or TNF-α were also significantly correlated (R = 0.82, p < 0.05; R = 0.88, p < 0.05, respectively). Directional changes in TLR2 / TLR4 and IFN-γ /TNF-α expression were concordant. However, there was no correlation found between TLR2 / TLR4 and IL-2. Differences in TLR2 and TLR4 expression strongly correlated with changes in IFN-γ and TNF-α suggest that the increased gene expressions of TLR2 and TLR4 in ITP patients may contribute to the pathophysiological progression of this disease by increasing the secretion of IFN-γ and TNF-α. Additional studies need to be performed to further clarify the role of TLRs -cytokines pathway in ITP.