Elevated adiponectin levels are associated with increased disease severity in patients with established rheumatoid arthritis (RA), study findings indicate.
“Adiponectin is a hormone released by adipose tissue with anti-diabetic, anti-atherogenic, and anti-inflammatory properties,” explain Jun Hashimoto (Osaka University, Japan) and colleagues.
The researchers add that the role of adiponectin in RA is controversial with some studies suggesting it is a potent driving force for RA and others indicating that it is a counterpart of local inflammatory processes.
To better define the role of adiponectin in RA, Hashimoto and team investigated the correlation between serum adiponectin levels and disease severity in 90 female patients with established RA (more than 5-years duration) and 42 age and body mass index (BMI)-matched controls.
The researchers used plain radiographs to assess joint erosion in 68 joints throughout the body and categorized the patients into a mild RA group (those with erosions in less than 20 joints) and a severe RA group (those with erosions in 20 or more joints).
As reported in the journal Clinical Rheumatology, the mean serum level of adiponectin, measured by enzyme immunoassay, was significantly higher in patients with RA (16.1 µg/ml) than in controls (9.1 µg/ml).
Furthermore, adiponectin levels were significantly higher in the severe RA group (n=53, 17.7 µg/ml) than in the mild RA group (n=37, 13.9 µg/ml) or control group (n=42, 9.1 µg/ml).
Univariate analysis of the relationship between serum adiponectin level and other variables showed that adiponectin correlated negatively with BMI. Multivariate analyses, adjusted for BMI, revealed a significant correlation between serum adiponectin level and RA disease severity.
To further investigate the time-course changes of serum adiponectin levels and severity of RA, the researchers reassessed 18 patients 2.5 years later. They found that the mean serum adiponectin level did not change significantly and that none of the mild RA patients had progressed to severe RA.
“Despite the limitation of observational study, we demonstrated that the severity of RA…correlated with serum adiponectin concentrations,” conclude Hasimoto et al.
“This finding should encourage further research to investigate the role of adiponectin in RA and design new adiponectin-based treatment strategies for RA.”