Severe disability in patients with relapsing-remitting multiple sclerosis is associated with profound changes in the regulation of leptin secretion.

Objectives: Experimental evidences indicate that leptin is involved in the neuroinflammatory process sustaining multiple sclerosis (MS). However, the relationship between leptin and body fat, as assessed by body mass index (BMI), in MS was not previously evaluated. It was the aim of this study to compare serum leptin levels between patients with MS and healthy controls and to evaluate the possible relationship between circulating leptin levels and disease severity. Patients and Methods: Eighty-four MS patients and 57 sex-matched healthy volunteers were enrolled. Serum leptin levels were measured in all patients and controls. MS patients were stratified in 3 groups according to their degree of disability as assessed by the Expanded Disability Status Scale (EDSS). Patients were classified as having low (33 patients with an EDSS score <1.5), intermediate (28 patients with an EDSS score from 2 to 3) and high disability (23 patients with an EDSS score ≥3.5). Results: No significant differences in serum leptin levels and BMI were observed between patients and controls. In patients with MS, serum leptin levels were significantly correlated with BMI in those patients with low (R(2) = 0.363; p < 0.001) and intermediate disability (R(2) = 0.408; p < 0.001), but not in patients with a higher disability score (R(2) = 0.064; p = 0.256). Conclusion: BMI, the major determinant of leptin level in physiological conditions, has a minor role in determining the serum levels of leptin in MS patients with a high EDSS score. Future longitudinal studies will be required in order to provide further insights into the regulation of leptin secretion in patients with MS.