The Concept of CMR

Inflammation and obesity

It is now clear that adipose tissue is much more than an organ that mobilizes energy stored in the form of triglycerides. Adipose tissue is now also considered an endocrine, paracrine, and autocrine organ that has a major impact on energy metabolism and related risk of diabetes and cardiovascular disease (CVD) (1). Leptin’s discovery in 1994 was a milestone in that it firmly established the true endocrine function of adipose tissue (2). Adipose tissue is now known to express and secrete a variety of bioactive peptides known as adipokines (Figure 1) that act at both a local (autocrine/paracrine) and systemic (endocrine) level. Among the wide variety of adipokines, adipocytes synthesize and secrete proteins such as classical cytokines (tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6)), growth factors (transforming growth factor-β), and proteins of the alternative complement system (adipsin, acylation-stimulating protein). Adipocytes also secrete proteins that participate in lipid transport (cholesterol ester transfer protein (CETP), retinol-binding protein (RBP)), vascular haemostasis (plasminogen activator inhibitor-1 (PAI-1), regulation of blood pressure (angiotensinogen), and glucose homeostasis (adiponectin). In addition to these efferent signals, adipose tissue expresses numerous receptors that allow it to respond to afferent signals from traditional hormone systems and the central nervous system.