Metformin administration induces hepatotoxic effects in paraoxonase-1-deficient mice

Current and future therapies for addressing the effects of inflammation on HDL cholesterol metabolism

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Inflammatory processes arising from metabolic abnormalities are known to precipitate the development of CVD. Several metabolic and inflammatory markers have been proposed for predicting the progression of CVD, including high density lipoprotein cholesterol (HDL-C). For ~50 years, HDL-C has been considered as the atheroprotective 'good' cholesterol because of its strong inverse association with the progression of CVD. Thus, interventions to increase the concentration of HDL-C have been successfully tested in animals; however, clinical trials were unable to confirm the cardiovascular benefits of pharmaceutical interventions aimed at increasing HDL-C levels. Based on these data, the significance of HDL-C in the prevention of CVD has been called into question. Fundamental in vitro and animal studies suggest that HDL-C functionality, rather than HDL-C concentration, is important for the CVD-preventive qualities of HDL-C. Our current review of the literature positively demonstrates the negative impact of systemic and tissue (i.e. adipose tissue) inflammation in the healthy metabolism and function of HDL-C. Our survey indicates that HDL-C may be a good marker of adipose tissue health, independently of its atheroprotective associations. We summarize the current findings on the use of anti-inflammatory drugs to either prevent HDL-C clearance or improve the function and production of HDL-C particles. It is evident that the therapeutic agents currently available may not provide the optimal strategy for altering HDL-C metabolism and function, and thus, further research is required to supplement this mechanistic approach for preventing the progression of CVD.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Metformin Potentiates the Benefits of Dietary Restraint: A Metabolomic Study

Prevention of the metabolic consequences of a chronic energy-dense/high-fat diet (HFD) represents a public health priority. Metformin is a strong candidate to be incorporated in alternative therapeutic approaches. We used a targeted metabolomic approach to assess changes related to the multi-faceted metabolic disturbances provoked by HFD. We evaluated the protective effects of metformin and explored how pro-inflammatory and metabolic changes respond when mice rendered obese, glucose-intolerant and hyperlipidemic were switched to diet reversal with or without metformin. Mice treated with metformin and diet-reversal showed a dramatically improved protection against HFD-induced hepatic steatosis, a beneficial effect that was accompanied by a lowering of liver-infiltrating pro-inflammatory macrophages and lower release of pro-inflammatory cytokines. Metformin combined with diet reversal promoted effective weight loss along with better glucose control, lowered levels of circulating cholesterol and triglycerides, and reduced adipose tissue content. Our findings underscored the ability of metformin to target the contribution of branched chain amino acids to adipose tissue metabolism while suppressing mitochondrial-dependent biosynthesis in hepatic tissue. The relationship between adipose tissue and liver might provide clinical potential for combining metformin and dietary modifications to protect against the metabolic damage occurring upon excessive dietary fat intake.