LncRNA GAS5 inhibits Th17 differentiation and alleviates immune thrombocytopenia via promoting the ubiquitination of STAT3

Background: The increased differentiation of T helper 17 cells (Th17) accelerates the development of immune thrombocytopenia (ITP), which is a common autoimmune disease with limited therapeutic methods. Recent studies have revealed that long non-coding RNAs (IncRNAs) play a critical role in autoimmune diseases, thus this study aims to investigate the effect of IncRNA GAS5 on the differentiation of Th17 cells in ITP. Methods: The expression of GAS5 in peripheral blood mononuclear cells (PBMCs) of ITP patients and spleen tissues of ITP mice was measured by qRT-PCR. The percentage of Th17 cells in CD44(+) cells was measured by flow cytometry. The combination between GASS and STAT3 was confirmed by RNA pull-down assay and RNA Binding Protein Immunoprecipitation (RIP). The ubiquitination of STAT3 was detected by ubiquitination assay and the interaction between STAT3 and TRAF6 was measured by Co-Immunoprecipitation (Co-IP). Finally, the effect of GASS on Th17 differentiation was investigated in vitro and in vivo using lentivirus (lenti)-GAS5. Results: GAS5 expression was downregulated both in PBMCs of ITP patients and spleen tissues of ITP mice. Overexpression of GAS5 suppressed Th17 differentiation while had no effect on Treg differentiation in naive CD4(+) cells. RNA pull-down and RNA immunoprecipitation assays confirmed the interaction between GAS5 and STAT3. Further studies showed GAS5 accelerated the degradation of STAT3 via promoting TRAF6-mediated ubiquitination. Overexpressing GAS5 suppressed Th17 differentiation in vitro and alleviated ITP in vivo via reducing STAT3. Conclusion: LncRNA GAS5 inhibited Th17 differentiation through promoting the TRAF6-mediated ubiquitination of STAT3, thus relieving ITP.