Interleukin 35 Activates Intratumor Neovascularization Via Enhanced Secretion of FGF2 in Hepatocellular Carcinoma Through The Recruitment of Neutrophils, and Blocking it Could Facilitate The Efficacy of The PD-1 Antibody

Abstract Background: Recently, more and more treatment strategies for Hepatocellular carcinoma (HCC) have emerged, but the therapeutic effect is still not satisfactory. This study is aimed to explore the mechanism of Interleukin 35 (IL-35) in promoting the progression of liver cancer and to explore the application value of IL-35 in the treatment of HCC.Methods: We used clinical tissue microarray (TMA) immunohistochemistry (IHC) to explore the prognostic value of IL-35 expression in patients with HCC. The effect of IL-35 on the function of HCC was explored by functional experiments including wound-healing assay, transwell, cell counting kit-8, cell adhesion assay and endothelial tube formation assay in vitro and mouse xenografts in vivo. And flow cytometry was used to study the effect of IL-35 on infiltrating immune cells in tumor. The molecular mechanism of the function of IL-35 on the progression of HCC was explored by sequencing, ELISA, WB, PCR and other technical means. Finally, through in vivo tumor animal experiments to explore the value of anti-IL-35 antibody and combined with anti-PD-1 antibody in the treatment of liver cancer.Results: High expression of IL-35 in patients with HCC were identified to be associated with poor prognosis. And we have found that IL-35 facilitated tumor progression by affecting neutrophil infiltration, angiogenesis, and CD8+ T-cell infiltration in a mouse model. Additionally, on the one hand C-C motif chemokine ligand 3 (CCL3) has been found to be a key factor mediating the recruitment of neutrophils by IL-35, on the other hand fibroblast growth factor 2 (FGF2) secreting by neutrophil when stimulated by IL-35 was also found to be the core cytokine to promote intratumoral angiogenesis. And IL-35 was also discovered to facilitated the adhesion of tumor to endothelial cells, with neutrophils further enhancing this effect in vitro and vivo. More important, anti-IL-35 antibody was found to be a valid treatment for HCC in xenograft tumor model, and it could give full play to the curative effect of 1:1＞2 when combination therapy with PD-1 antibody.Conclusion: Our data show that the expression of IL-35 in patients with HCC is an important tumor promoting factor. The application of anti-IL-35 antibody and treatment combined anti-IL-35 antibody with anti-PD-1 antibody have potential therapeutic value in the treatment of liver cancer.