30 In the second part of our study we showed that αVEGFR2 treatment prevents the progression of NASH by attenuating steatosis and inflammation, both in a preventive and therapeutic setting, thereby confirming our hypothesis that angiogenic factors play an early role in the disease progression from steatosis to NASH. The grade of steatosis and inflammation was significantly less in the liver of αVEGFR2-treated mice in a preventive setting. Moreover, αVEGFR2 treatment was able to block the progression to NASH in mice with steatosis and inflammation. This could indicate that αVEGFR2 treatment could temper the effect of angiogenic stimuli. Moreover, in vitro we
found that αVEGFR2 therapy significantly
decreased lipid accumulation in fat-laden primary hepatocytes. This is in line with previous studies that Palbociclib mw the VEGF/VEGFR2 pathway is critical for both angiogenesis and adipogenesis during de novo adipose tissue formation from preadipocytes.31 Moreover, previous studies CHIR-99021 ic50 showed that angiogenic, inflammatory, and lipogenic processes are tightly crosslinked and are capable of sustaining each other.32 The reason why αPlGF treatment did not have a significant effect on the liver histology of mice with NASH compared to untreated mice with NASH could probably lie in the fact that PlGF signals only through the VEGFR1 pathway and not by way of VEGFR2. To obtain a clear insight into the molecular events, we examined the transcript levels of lipogenic genes (Scd1 and L-fabp1). These experiments showed that αVEGFR2 treatment increased Scd1 gene expression
in both a preventive and therapeutic setting. Scd1 plays a key role in the prevention of steatohepatitis by partitioning excess lipid into monounsaturated fatty acids that can be safely stored.33 The literature confirms our results that MCD feeding causes a significant decrease in hepatic Scd1 gene expression as well as the down-regulation of L-fabp1 gene expression compared to mice fed a control diet.34, 35 Our study showed that αVEGFR2 increases Scd1 gene expression to a more normal Scd1 expression in the liver of mice treated in a therapeutic and preventive setting compared to untreated mice fed an Morin Hydrate MCD diet. This could suggest that αVEGFR2 therapy improves lipid metabolism in the liver. However, the exact molecular mechanism responsible for MCD diet-induced down-regulation of Scd1 as well as changes in Scd1 expression in human NAFLD, and its relation to liver damage and disease progression, remain unknown and will require further investigation. In summary, we demonstrated the role for VEGF in the pathophysiology in two mouse models for NASH. This study shows for the first time that αVEGFR2 treatment attenuates steatosis and inflammation in the liver of mice with NASH both in a preventive and therapeutic setting.