C1q/TNF-Related Protein-9 (CTRP9) Levels Are Associated With Obesity and Decrease Following Weight Loss Surgery.

CONTEXT: C1q/TNF-related protein-9 (CTRP9) is a novel adipokine that has beneficial metabolic and cardiovascular effects in various animal models. Alterations in circulating CTRP9 have also been observed in patients with cardiovascular disease and diabetes, but little is known about the impact of obesity and bariatric surgery on CTRP9 concentrations. OBJECTIVE: The aim of this study was to compare CTRP9 levels in obese and lean subjects and to determine whether circulating CTRP9 levels in morbidly obese patients are altered by bariatric surgery. DESIGN, SETTING, AND PARTICIPANTS: Fifty-nine obese bariatric surgical patients and 62 lean controls were recruited to participate in a cross-sectional study at an academic medical center. The obese patients were further invited to participate in a cohort study, and 21 returned for analysis at 3 and 6 months postsurgery. INTERVENTION: Bariatric surgery (Roux-en-Y gastric bypass and vertical sleeve gastrectomy) was the intervention for this study. MAIN OUTCOME MEASURES: Fasting serum was obtained from all subjects on entry to the study and was analyzed in the core laboratory for hemoglobin A1c, glucose, aspartate aminotransferase, alanine aminotransferase, total cholesterol, high- and low-density lipoprotein cholesterol, and triglycerides; CTRP9, insulin, adiponectin, and leptin were measured by ELISA. Serum from the patients in the cohort study was also analyzed at 3 and 6 months. RESULTS: Serum CTRP9 was significantly higher in the obese group compared to the lean group. CTRP9 was associated with obesity, even after controlling for age, gender, and ethnicity. Following bariatric surgery, there was a significant decrease in weight at 3 and 6 months postprocedure, accompanied by decreases in CTRP9, hemoglobin A1c and leptin, and an increase in serum adiponectin. CONCLUSIONS: CTRP9 levels are elevated in obesity and significantly decrease following weight loss surgery. Our data suggest that CTRP9 may play a compensatory role in obesity, similar to that of insulin, and is down-regulated following weight loss surgery.