Vaspin in obesity and diabetes: pathophysiological and clinical significance

Vaspin (visceral adipose tissue-derived serpin; serpinA12) was originally identified as an adipokine, which is predominantly secreted from visceral adipose tissue in Otsuka Long-Evans Tokushima fatty (OLETF), an animal model of obesity and type 2 diabetes. Consistent with that higher vaspin serum concentrations and increased vaspin mRNA expression in human adipose tissue were found to be associated with obesity, insulin resistance, and type 2 diabetes in humans. However, the mechanisms how vaspin secretion may be linked to deterioration of glucose metabolism and insulin sensitivity are not entirely understood. Vaspin serum concentrations show a food intake-related diurnal variation. Vaspin is also expressed in the skin, hypothalamus, pancreatic islets, and stomach. Administration of vaspin to obese mice improves glucose tolerance, insulin sensitivity, and reduces food intake. Until now molecular target(s) of vaspin and its mode of action are unknown. Thus, identification of the proteases, which are inhibited by vaspin may lead to the development of novel strategies in the treatment of obesity, diabetes and insulin resistance. This review discusses the clinical relevance of vaspin in the pathophysiology of obesity and type 2 diabetes.