IL-10 derived from Hepatocarcinoma cells improves human induced regulatory T cells function via JAK1/STAT5 pathway in tumor microenvironment

Forkhead box P3 (Foxp3) expressing CD4(+)CD25(+) regulatory T cells (Tregs), an essential subset of immune T cells for maintaining immune homeostasis is implicated as a negative regulator in an anti-tumor immune response. Current researches suggest that reducing tumor-infiltrating Tregs contribute to enhanced anti-cancer effect. However, the mechanism of infiltration of a large number of Tregs into tumor tissues is still unclear. In this study, human induced Tregs (iTregs) were co-cultured with human hepatocytes and various types of cancer cells (HepG2, NSCLC, and AsPC-1) supernatants. Foxp3, multiple cytokines, levels of apoptosis and suppressive ability of iTregs were detected by FACS. Western blot was employed to test of proteins. Impact of HepG2 supernatants on T cell subpopulations differentiation, cytokines in supernatants were examed by FACS and ELISA respectively. Anti-IL-10R antibody and JAK1 inhibitor were used to reconfirm the role of tumor-derived IL-10 play in the regulation on iTregs. Hepatocarcinoma cells (HCC) supernatants treatment increases Foxp3 stability and reduces apoptosis level in human iTregs without influencing its differentiation trend. Furthermore, IL-10 was found to be extremely higher in HCC supernatants than other groups, IL-10R blockade neutralize the effect of HCC supernatants on iTregs in vitro obviously. HCC supernatants also reversed IL-1 beta/6 triggered decline on Foxp3 which may be related to higher expression of JAK1 and elevated phosphorylation level of STAT5 induced by IL-10. Our results suggest that improved stability and abnormal accumulation of Tregs in tumor microenvironment is IL-10/JAK1/STAT5 signal pathway-dependent and provide a novel approach for improving the efficiency of anti-tumor immunotherapy.

Automated summary

The study found that treatment with hepatocarcinoma cell (HCC) supernatants increased the stability of Foxp3 and reduced apoptosis levels in human iTregs without affecting their differentiation trend. Furthermore, IL-10 levels were significantly higher in HCC supernatants compared to other groups, and blocking the IL-10 receptor neutralized the effect of HCC supernatants on iTregs. HCC supernatants also reversed the decline in Foxp3 triggered by IL-1 beta/6, potentially due to the higher expression of JAK1 and elevated phosphorylation levels of STAT5 induced by IL-10.