The prevalence of obesity and obesity-related diseases focussed an increasing interest, over the last 10 years, on white adipose tissue and its derived bioactive peptides, being the discovery of leptin in 1994 the trigger of the renaissance of the studies about adipose tissue.

Leptin was initially depicted as the most important anorexigenic factor with neuroendocrine actions, but it has been later shown to significantly modulate immune and inflammatory processes. Leptin is a dual molecule: apart from its previously envisaged metabolic activities, increasing evidence frames leptin as a novel pro-inflammatory adipokine and, at present it might be easily considered one of the relevant links among immune system, inflammatory response and neuroendocrine system. Leptin regulates and participates both in immune homeostasis and inflammatory processes by acting as a modulator of cell activity and playing an active role in articular degenerative inflammatory diseases such as osteoarthritis and rheumatoid arthritis, but also in a host of autoimmune inflammatory conditions such as encephalomyelitis, type-1 diabetes, and bowel inflammation. This review will be focussed more on the adipokine facet of leptin, even though its role as metabolic hormone will be also addressed. In addition, the role od other relevant adipokines in inflammation will be covered.