Adipose tissue at the crossroads in the development of the metabolic syndrome, inflammation and atherosclerosis

Abstract

The authors analyze insulin resistance, the metabolic syndrome and endothelial dysfunction as consequence of a common antecedent, a low grade inflammation, indicating that in obesity there is a chronically activated inflammatory state of the adipose tissue. Furthermore, the inflammatory signaling is discussed according to the adipose tissue depot, visceral or subcutaneous. RESUMOOs autores analisam a resistência à insulina, a síndrome metabólica e a disfunção endotelial como consequência de um antecedente comum, a inflamação de baixo nível, o que mostra que a obesidade é um estado inflamatório cronicamente ativado do tecido adiposo. Discute-se, aqui, a sinalização inflamatória de acordo com a localização do tecido adiposo subcutâneo ou visceral.

Leptin: molecular mechanisms, systemic pro-inflammatory effects, and clinical implications

“…Obesity, especially visceral adiposity, is considered an inflammatory disease, since the adipose tissue is able to produce inflammatory cytokines or collaborate with their production by other tissues (2). Also, obese pa tients exhibit higher level of inflammatory markers such as C reactive protein, TNF a, IL 6, IL 18, MIF (macrophage migration inhibitory factor), haptoglo bin, SAA (serum amyloid A), and plasminogen acti vator inhibitor 1.…”

“…A lthough initially considered as a simple storage of fat, overwhelming evidence led the adipose tissue to be conceptualized as an endocrine organ (1,2). The discovery of leptin has dramatically changed the under standing of the physiological importance of the adipose tissue, making it clear that the adipose tissue synthe sizes and releases this key hormone that plays a crucial role to signal the brain to control food intake and ener gy expenditure (3).…”

Obesity phenotypes: normal-weight individuals with metabolic disorders versus metabolically healthy obese

“…Generally, the risk of metabolic syndrome is lower when body fat is stored in the peripheral part of the body [13,[19][20][21]. Visceral adipose tissue (VAT) is stored in the abdominal cavity and surrounds internal organs, while subcutaneous adipose tissue is mainly located peripherally (Fig.…”

“…The excess of visceral fat supports pathological vascular changes by secretion of pro-inflammatory and pro-atherosclerotic mediators, such as interleukin 6 (IL-6), plasminogen activator inhibitor-1 (PAI-1), and glucocorticoids, which account for the development of cardiovascular diseases such as coronary artery disease and cardiac dysfunction [19][20][21]23]. It has also been observed that increased concentrations of C-reactive protein (CRP), tumour necrosis factor [19,21]. Greater insulin resistance has been observed in patients with visceral fat obesity.…”

“…In contrast to visceral fat, it secretes adiponectin, which has a protective and anti-inflammatory role [19,21]. In many studies it has been suggested that the excess of SAT has a stronger correlation with insulin sensitivity than VAT [13].…”