ABSTRACT
BACKGROUND & AIMS: Hepatic steatosis is a hallmark of non-alcoholic fatty liver disease (NAFLD), a common comorbidity in type 2 diabetes mellitus (T2DM). The pathogenesis of NAFLD is complex and involves the crosstalk between the liver and the white adipose tissue (WAT). Vascular endothelial growth factor B (VEGF-B) has been shown to control tissue lipid accumulation by regulating the transport properties of the vasculature. The role of VEGF-B signaling and the contribution to hepatic steatosis and NAFLD in T2DM is currently not understood. METHODS: C57BL/6 J mice treated with a neutralizing antibody against VEGF-B, or mice with adipocyte-specific overexpression or under-expression of VEGF-B (AdipoqCre+/VEGF-BTG/+ mice and AdipoqCre+/Vegfbfl/+mice) were subjected to a 6-month high-fat diet (HFD), or chow-diet, whereafter NAFLD development was assessed. VEGF-B expression was analysed in WAT biopsies from patients with obesity and NAFLD in a pre-existing clinical cohort (n = 24 patients with NAFLD and n = 24 without NAFLD) and correlated to clinicopathological features. RESULTS: Pharmacological inhibition of VEGF-B signaling in diabetic mice reduced hepatic steatosis and NAFLD by blocking WAT lipolysis. Mechanistically we show, by using HFD-fed AdipoqCre+/VEGF-BTG/+ mice and HFD-fed AdipoqCre+/Vegfbfl/+mice, that inhibition of VEGF-B signaling targets lipolysis in adipocytes. Reducing VEGF-B signaling ameliorated NAFLD by decreasing WAT inflammation, resolving WAT insulin resistance, and lowering the activity of the hormone sensitive lipase. Analyses of human WAT biopsies from individuals with NAFLD provided evidence supporting the contribution of VEGF-B signaling to NAFLD development. VEGF-B expression levels in adipocytes from two WAT depots correlated with development of dysfunctional WAT and NAFLD in humans. CONCLUSIONS: Taken together, our data from mouse models and humans suggest that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. IMPACT AND IMPLICATIONS: Non-alcoholic fatty liver disease (NAFLD) is a common comorbidity in type 2 diabetes mellitus (T2DM) and has a global prevalence of between 25-29%. There are currently no approved drugs for NAFLD, and given the scale of the ongoing diabetes epidemics, there is an urgent need to identify new treatment options. Our work suggests that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. The neutralizing anti-VEGF-B antibody, which was used in this study, has already entered clinical trials for patients with diabetes. Therefore, we believe that our results are of great general interest to a broad audience, including patients and patient organizations, the medical community, academia, the life science industry and the public.
