Depot-specific regulation of autotaxin with obesity in human adipose tissue

Autotaxin (ATX) is a lysophospholipase D involved in synthesis of a bioactive mediator: lysophosphatidic. ATX is abundantly produced by adipocytes and exerts a negative action on adipose tissue expansion. In both mice and humans, ATX expression increases with obesity in association with insulin resistance. In the present study, fat depot-specific regulation of ATX was explored in human. ATX mRNA expression was quantified in visceral and subcutaneous adipose tissue in obese (BMI > 40 kg/m(2); n = 27) and non-obese patients (BMI < 25 kg/m(2); n = 10). Whatever the weight status of the patients is, ATX expression was always higher (1.3- to 6-fold) in subcutaneous than in visceral fat. Nevertheless, visceral fat ATX was significantly higher (42 %) in obese than in non-obese patients, whereas subcutaneous fat ATX remained unchanged. In obese patients, visceral fat ATX expression was positively correlated with diastolic arterial blood pressure (r = 0.67; P = 0.001). This correlation was not observed with subcutaneous fat ATX. Visceral fat ATX was mainly correlated with leptin (r = 0.60; P = 0.001), inducible nitric oxide synthase (r = 0.58; P = 0,007), and apelin receptor (r = 0.50; P = 0.007). These correlations were not observed with subcutaneous fat ATX. These results reveal that obesity-associated upregulation of human adipose tissue ATX is specific to the visceral fat depot.