Impact of Systemic Inflammation and Autoimmune Diseases on apoA-I and HDL Plasma Levels and Functions

The cholesterol of high-density lipoproteins (HDLs) and its major proteic component, apoA-I, have been widely investigated as potential predictors of acute cardiovascular (CV) events. In particular, HDL cholesterol levels were shown to be inversely and independently associated with the risk of acute CV diseases in different patient populations, including autoimmune and chronic inflammatory disorders. Some relevant and direct anti-inflammatory activities of HDL have been also recently identified targeting both immune and vascular cell subsets. These studies recently highlighted the improvement of HDL function (instead of circulating levels) as a promising treatment strategy to reduce inflammation and associated CV risk in several diseases, such as systemic lupus erythematosus and rheumatoid arthritis. In these diseases, anti-inflammatory treatments targeting HDL function might improve both disease activity and CV risk. In this narrative review, we will focus on the pathophysiological relevance of HDL and apoA-I levels/functions in different acute and chronic inflammatory pathophysiological conditions

LXR beta is required for adipocyte growth, glucose homeostasis, and beta cell function

Liver X receptors (LXR) alpha and beta are nuclear oxysterol receptors with established roles in cholesterol, lipid, and carbohydrate metabolism. Although LXRs have been extensively studied in liver and macrophages, the importance for development and metabolism of other tissues and cell types is not as well characterized. We demonstrate here that although LXR alpha and LXR beta are not required for adipocyte development per se, LXR beta is required for the increase in adipocyte size that normally occurs with aging and diet-induced obesity. Similar food intake and oxygen consumption in LXR beta-/- mice suggests that reduced storage of lipid in adipose tissue is not due to altered energy balance. Despite reduced amounts of adipose tissue, LXR beta-/- mice on a chow diet have insulin sensitivity and levels of adipocyte hormones similar to wild type mice. However, these mice are glucose-intolerant due to impaired glucose-induced insulin secretion. Lipid droplets in pancreatic islets may result from accumulation of cholesterol esters as analysis of islet gene expression reveals that LXR beta is required for expression of the cholesterol transporters, ABCA1 and ABCG1. Our data establish novel roles for LXR beta in adipocyte growth, glucose homeostasis, and beta cell function

Plasma irisin levels predict telomere length in healthy adults

The ageing process is strongly influenced by nutrient balance, such that modest calorie restriction (CR) extends lifespan in mammals. Irisin, a newly described hormone released from skeletal muscles after exercise, may induce CR-like effects by increasing adipose tissue energy expenditure. Using telomere length as a marker of ageing, this study investigates associations between body composition, plasma irisin levels and peripheral blood mononuclear cell telomere length in healthy, non-obese individuals. Segmental body composition (by bioimpedance), telomere length and plasma irisin levels were assessed in 81 healthy individuals (age 43±15.8 years, BMI 24.3±2.9 kg/m2). Data showed significant correlations between log-transformed relative telomere length and the following: age (p<0.001), height (p=0.045), total body fat percentage (p=0.031), abdominal fat percentage (p=0.038), visceral fat level (p<0.001), plasma leptin (p=0.029) and plasma irisin (p=0.011), respectively. Multiple regression analysis using backward elimination revealed that relative telomere length can be predicted by age (b=−0.00735, p= 0.001) and plasma irisin levels (b=0.04527, p=0.021). These data support the view that irisin may have a role in the modulation of both energy balance and the ageing process