RETN and metabolic syndrome: In fact, the adypocite produces the adipose derived hormones: leptin [21,22] and adiponectin [22,23], playing a key role in regulating energy balance, while the adipocytokines (resistin, chemerin, visfatin, interleukin-6, plasminogen activator inhibitor-1, retinol binding protein 4 and tumor necrosis factor alpha, angiotensin) are also immunomodulating agents [24]; anyway, all these substances are implicated in developing metabolic syndrome [25].