Hepatocellular carcinoma is accelerated by NASH involving M2 macrophage polarization mediated by hif-1?induced IL-10.

ABSTRACT: Obesity-related inflammation promotes cancer development. Tissue resident macrophages affect tumor progression and the tumor micro-environment favors polarization into alternatively activated macrophages (M2) that facilitate tumor invasiveness. Here, we dissected the role of western diet-induced NASH in inducing macrophage polarization in a carcinogen initiated model of hepatocellular carcinoma (HCC). Adult C57BL/6 male mice received diethyl nitrosamine (DEN) followed by 24 weeks of high fat-high cholesterol-high sugar diet (HF-HC-HSD). We assessed liver MRI and histology, serum ALT, AFP, liver triglycerides, and cytokines. Macrophage polarization was determined by IL-12/TNF? (M1) and CD163/CD206 (M2) expression using flow cytometry. Role of hif-1?-induced IL-10 was dissected in hepatocyte specific hif-1?KO and hif-1?dPA (over-expression) mice. The western diet-induced features of NASH and accelerated HCC development after carcinogen exposure. Liver fibrosis and serum AFP were significantly increased in DEN + HF-HC-HSD mice compared to controls. Western diet resulted in macrophage (F4/80⁺CD11b⁺) infiltration to liver and DEN + HF-HC-HSD mice showed preferential increase in M2 macrophages. Isolated hepatocytes from western diet fed mice showed significant upregulation of the hypoxia-inducible transcription factor, hif-1?, and livers from hif-1? over-expressing mice had increased proportion of M2 macrophages. Primary hepatocytes from wild-type mice treated with DEN and palmitic acid in vitro showed activation of hif-1? and induction of IL-10, a M2 polarizing cytokine. IL-10 neutralization in hepatocyte-derived culture supernatant prevented M2 macrophage polarization and silencing hif-1? in macrophages blocked their M2 polarization. Therefore, our data demonstrate that NASH accelerates HCC progression via upregulation of hif-1? mediated IL-10 polarizing M2 macrophages.

SUBMITTER: Ambade A 

PROVIDER: S-EPMC5087291 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature