Effect of Cytokine Gene Polymorphisms on Eltrombopag Reactivity in Japanese Patients with Immune Thrombocytopenia

BACKGROUND: Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by low platelet counts resulting from antiplatelet autoantibodies. Analysis of polymorphisms in cytokine-encoding genes is important for understanding the pathophysiology of ITP and selecting appropriate treatments. We investigated associations between polymorphisms in cytokine-encoding genes and responses to therapy in Japanese patients with ITP. METHODS: The participants in this study comprised 153 patients with ITP and 70 healthy controls. We extracted data on sex, age, platelet counts, bleeding symptoms, and therapeutic responses, including those to prednisolone (PSL) and eltrombopag. Genomic DNA was isolated from peripheral blood and polymorphisms in TNF-α, IL-10, TGF-β(1), and IFN-γ genes were analyzed using the PCR-SSP method. RESULTS: Our results showed that the TGF-β(1) +869 C/C genotype might be related to ITP in Japanese patients. The IL-10 −592 C/C and A/A, −819 C/C and T/T, and −1082, −819, −592 ATA/ATA genotypes might be associated with reactivity to PSL. Furthermore, the IL-10 −592 C/A −819 C/T genotypes, IL-10 ACC/ATA genotype, and TGF-β(1) +869 T/T and T/C genotypes might be linked to the response to eltrombopag. CONCLUSION: Our results indicate that analysis of polymorphisms in cytokine-encoding genes could aid in understanding PSL and eltrombopag responsiveness in Japanese patients with ITP.