Non-alcoholic steatohepatitis alters antigen-specific response against hepatocellular carcinoma in mice

Abstract

Abstract Objective Non-alcoholic steatohepatitis (NASH) can lead to hepatocellular carcinoma (HCC). At time immunotherapy is used as first line treatment of advanced HCC, the impact of NASH on anti-cancer immunity remains unclear. We aim at assessing the tumor-specific T cell immune response in the presence of NASH in a mouse model of HCC recurrence. Methods We engineered an HCC cell line (RIL-175) with a cytoplasmic expression of ovalbumin (OVA) protein. C57BL/6N mice fed a high-fat (HFD) or a control diet (CD) for 35 weeks were injected in the portal vein with 1.5.105 RIL-175-LV-OVA-GFP cells. Results After 35 weeks of HFD, mice were obese and developed a massive steatosis with inflammation. In the liver of HFD-fed mice, we observed an increase of the CD8+ T cell subset corresponding to an expansion of the population of CD44+ CXCR6+ PD-1+ CD8+ T cells, known to promote NASH lesions. Fourteen days after injecting RIL-LV-OVA-GFP cells, HFD-fed mice developed a higher percentage of peripheral OVA-specific CD8 T cells than CD-fed mice (8.31 vs. 3.67%; p=0.010), but these cells were not able to prevent HCC growth, resulting in larger tumors in HFD-fed mice (620 vs. 1603mm3, p=0.051). In the liver, OVA-specific CD44+ CXCR6+ CD8+ cells were present in a similar manner in CD and HFD-fed mice, however with a higher expression of PD-1 in HFD-fed mice, suggesting a lower immune activity (MFI 12605 vs. 16083, p=0.0159). Using anti-CD122 antibody acting in decreasing the CXCR6+ PD-1+ cell subset, we were able to restore OVA-specific CD8 activity through a decrease in PD-1 expression (MFI 16406 vs. 10516, p=0.0571), and to decrease HCC growth compared to HFD mice non treated with anti-CD122 (p=0.0286). Conclusion The immune system is altered and fails to prevent HCC growth in HFD-fed mice. This effect is primarily linked to a higher representation of CD44+ CXCR6+ PD-1+ CD8+ T cells. Treatment with anti-CD122 act on these cells, and prevent HCC growth.