Abstract 14521: Association of Serum Leptin and Abdominal Aortic Inflammation in Rheumatoid Arthritis

Abstract

Introduction: Rheumatoid arthritis (RA) is an autoimmune disease associated with increased risk of atherosclerosis. Leptin may indirectly contribute to atherogenesis, but its role in RA is not clear. Hypothesis: We aimed to study the correlation between leptin and inflammation in the abdominal aorta (AA) assessed by 18F-FDG PET/CT in RA patients. Methods: We retrospectively analyzed the data of 18 RA patients (mean age 56.0±11.9, 14 male). All patients were administered 18F-FDG intravenously, and full-body PET/CT scans were acquired 180 minutes later. Regions of interest were delineated around the wall of the AA, with a superior border at the aortic hiatus of the diaphragm and an inferior border at the bifurcation of iliac arteries. Mean standard uptake values per axial slice were averaged to calculate the average SUVmean (aSUVmean). BMI, visceral fat area (VFA), and serum logarithmically transformed leptin (ln-leptin) were obtained. Patients were divided into low- and high-BMI groups, with a cutoff of 25 kg/m2. Results: Mean BMI (kg/m2) and VFA (cm2) between the low- and high-BMI groups were 21.7 vs. 31.4 (p<0.001) and 72.3 vs. 157.0 (p=0.002), respectively. Serum ln-leptin and aSUVmean were significantly increased in the high-BMI group (7.2±0.9 vs. 9.8±1.1, p<0.001; 1.4 vs. 1.7, p=0.04). On regression analysis, serum ln-leptin correlated positively with aSUVmean (r=0.59, p=0.01). Conclusion: In our study, higher serum leptin levels moderately correlated with 18F-FDG uptake in the AA, which reflects inflammation and atherogenic activity. Future studies are warranted to further elucidate the role of leptin in co-morbid atherosclerosis in patients with RA.