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 AT-PIII 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.