The relationship of body mass index with serum TGF-beta level and clinical findings in patients with systemic sclerosis

INTRODUCTION: Systemic sclerosis (SSc) is an inflammatory disease, characterized by widespread fibrosis of affected tissue. Obesity is characterized as a chronic inflammatory state and affects the production of cytokines. The aim of the present study was to evaluate whether obesity alters clinical characteristics and serum transforming growth factor-beta (TGF-β) levels in patients with SSc.
METHODS: Eighty-six patients with SSc enrolled in this study. Body mass indexes (BMI) were calculated and the cases were divided into 3 groups (normal, overweight and obese). In each group, the extent of skin involvement was determined by respectively modified Rodnan skin score (mRSS), pulmonary function test and carbon monoxide diffusing capacity were measured. TGF-β levels were measured by the method of enzyme-linked immunosorbent assay.
RESULTS: 38 patients were normal weight (BMI: ≤25 kg/m2), 27 patients were overweight (BMI: 25-30 kg/m2) and 21 patients were obese (BMI >30 kg/m2). Their clinical and laboratory findings were similar. However, serum TGF-β level was significantly lower in the obese SSc patients compared to the patients with normal weight.
DISCUSSION AND CONCLUSION: These results suggest that obesity does not affect the severity of SSc. The cause of decreased serum TGF-β level in obese patients may be increased fat tissue instead of SSc. Despite of decreased TGF-β level, the severity of SSc is not different between obese and non-obese patients. The ways apart from TGF-β maybe responsible for the SSc severity in obese SSc patients.