Obesity affects over 40% of the US population and predisposes individuals to metabolic syndrome, which is associated with a 50% increase in the risk of cardiovascular events. A documented clinical manifestation of obesity is a procoagulant and anti-fibrinolytic state. Elevated levels of circulating plasminogen activator inhibitor (PAI) -1 are correlated with metabolic syndrome, and PAI-1-deficient mice are protected from diet-induced obesity (DIO) . However, an unresolved question is whether plasminogen itself influences the development of obesity and associated disease sequelae? Here, we analyzed the impact of genetically-imposed plasminogen deficiency on the development of DIO and associated pathologies. Over the course of 20 weeks, plasminogen-deficient (Plg-) mice gained as much weight as the control mice (Plg+) on HFD, although HFD-fed Plg- mice had larger epididymal white adipose tissues than those of HFD-fed Plg+ mice. In contrast, while HFD-fed Plg+ animals displayed a fatty liver disease phenotype characterized by histological evidence of steatosis, elevated triglyceride content, and hepatocellular injury, HFD-fed Plg- mice were protected from developing each of these pathologies. HFD-fed Plg+ mice also developed hypercholesterolemia, whereas circulating cholesterol levels in Plg- mice were comparable to LFD-fed mice. Intriguingly, while the brown adipose tissue mass was comparable between diet and genotype, there was an upregulation of uncoupling protein-1 (Ucp1) expression in BAT of HFD-fed Plg- mice. Notably, whereas HFD-fed Plg+ mice showed evidence of insulin resistance as revealed by compromised glucose clearance, HFD-fed Plg- mice were partially protected. Collectively, our data suggest that plasmin (ogen) contributes to HFD-induced fatty liver disease and insulin resistance, and that plasminogen deficiency imposes a state of metabolically healthy obesity.
W.S.Hur: None. Y.Nguyen: None. Y.Patel: None. K.C.King: None. M.J.Flick: None.
National Institutes of Health (RDK112778)