Relationship between leptin and regulatory T cells in systemic lupus erythematosus: preliminary results.

OBJECTIVE Crescent literature data demonstrated a role of adipokines in immune responses, particularly leptin is involved in wide spectrum of pro-inflammatory functions. Several evidences suggested that leptin is able to inhibit T regulatory cells proliferation and function in vitro models. In the present study, we investigate the relationship between leptin and circulating T regulatory cells (Tregs) in patients affected by systemic lupus erythematosus (SLE). PATIENTS AND METHODS 13 SLE patients and 11 healthy controls were enrolled. Metabolic syndrome and cardiovascular parameters were evaluated. Serum leptin levels were detected by commercial ELISA kit and circulating regulatory T cells were determined by FACS analysis as CD4+CD25highFOP3+ lymphocytes. RESULTS Metabolic syndrome, defined by ATPIII criteria, was more prevalent in SLE compared to controls (38.4% vs. 0%, p = 0.04), as well as arterial hypertension (38.4% vs. 0%, p = 0.04). We did not find significant differences in mean leptin levels among SLE and controls (13.13 ± 1.51 ng/ml vs. 9.48 ± 8.67 ng/ml, p = 0.6). Mean Tregs percentage of total CD4 were 1.27 ± 0.9 in SLE vs. 2.8 ± 1.2 in healthy controls (p = 0.001). We found a negative correlation between leptin levels and Tregs percentage of total CD4 in SLE patients (r = 0.4, p = 0.01). CONCLUSIONS Our results suggest a role of leptin in the regulation of circulating T regulatory cells amount in human SLE.