Interleukin 35 promotes progression of hepatocellular carcinoma by recruiting neutrophils

BACKGROUND: A growing number of therapeutic strategies against hepatocellular carcinoma (HCC) have emerged. However, their efficacy remains limited. This study investigated the mechanism of interleukin-35 (IL-35) in the progression of HCC and its potential application in HCC treatment. METHODS: The expression of IL-35,Gp130 ,IL12-Rβ2, CCL3,etc. in HCC tissues was detected by immunohistochemistry(IHC), and the expression of IL-35 in HCC cell lines was detected by fluorescence assay. Kaplan-Meier survival analysis of IL-35 and its receptor in relation to overall survival(OS) and recurrence free survival(RFS) in patients with HCC. The mouse subcutaneous tumor models to study the effects of IL-35 on HCC growth and immune cells. Western blot were used to detect the expression IL-35, CCL3, FGF2, and flow cytometric plot were performed to explore the immune cells infiltration in the tumor tissue. RESULTS: High expression of IL-35 in patients with HCC was associated with poor prognosis. Furthermore, IL-35 could facilitate tumor progression by affecting neutrophil infiltration, angiogenesis, and CD8+ T-cell infiltration. Additionally, CCL3 was a key factor mediating the recruitment of neutrophils by IL-35. FGF2 derived from neutrophils stimulated by IL-35 promoted intratumoral angiogenesis. IL-35 also facilitated the adhesion of tumors to endothelial cells, with neutrophils further enhancing this effect both. Anti-IL-35 antibody combined with anti-PD1 antibody significantly enhanced which therapeutic effect in HCC. CONCLUSIONS: Our data show that the high expression of IL-35 in patients with HCC is an important tumor promoter. Combined treatment with anti-IL-35 and anti-PD1 antibodies have potential therapeutic effect against HCC.