Maintenance of Subcutaneous Fat Homeostasis Improves Systemic Metabolic Dysfunction in Obesity

摘要

Obesity and diabetes continue to be major health problems worldwide. The fat tissues distributed throughout the body can be classified into two main types-brown and white adipose tissue. Evidence has been found to suggest that adipose tissue dysfunction has a causative role in the development of systemic metabolic disorders. Brown adipose tissue (BAT) was initially reported to be involved in heat generation. BAT is predominantly found in infants and rodents and was once thought to disappear with aging. However, BAT has since been identified in adults and is now recognized to be a metabolically active tissue that contributes to the maintenance of systemic metabolism. BAT has a massive capacity to dissipate energy as heat, and the development of BAT dysfunction due to metabolic stress promotes the progression of systemic metabolic dysfunction. Visceral fat is a metabolically active endocrine organ that secretes several humoral mediators known as adipokines. Chronic sterile inflammation occurs in visceral fat as a result of metabolic stress, and an imbalance between production of proinflamma-tory and anti-inflammatory adipokines leads to systemic metabolic dysfunction. Compared with visceral fat, subcutaneous fat has more beneficial effects on systemic metabolism. Subcutaneous fat contains beige cells, which are identified as cells positive for the uncoupling protein 1 and negative for the myogenic factor 5. Beige cells that arise from the browning of subcutaneous fat improve systemic metabolic dysfunction in obesity. Accordingly, many studies have investigated the browning of subcutaneous fat and its potential to combat obesity.