Study On Leptin Expression And The Correlation Between The Expression Of Serum Leptin And The CD4~+CD25~+Foxp3~+Treg Cells In SLE Patients

Objective: SLE is a chronic systemic autoimmune disease in which autoreactive immune cells produce multiple autoantibodies due to the dysfunction of immune tolerance, causing inflammation and loss of organ function. Regulatory T cells(Treg) are definitely important in immune tolerance. Leptin, a polypeptide hormone, play a key role in the regulation of weight, endocrine, reproduction, immune response, and inflammation, respectively. Studies have shown that circulating leptin is abnormally elevated in patients with SLE, however, little is known on how leptin can contribute to the pathogenesis of SLE, and different groups make different conclusions on associations of leptin level and disease activity. Leptin favors a negative modulation on activation and proliferation of tregs. In multiple sclerosis patients, the increasing serum leptin is negatively associated with decreasing percentage of tregs. Of note, in patients with SLE, it remains elusive from previous reports. In our study, we try to address the associations between leptin and SLE disease activity, leptin and tregs and elucidate the possible mechanisms of leptin on lupus.Methods:1 Forty-seven eligible participants from the Department of Immunology and Rheumatology of the Second Hospital of Hebei Medical University are female who fulfilled ≥4 of the American College of Rheumatology(ACR) 1997 revised criteria for the classification of SLE. They were divided into mild activity group(5-9 scores, n=12), moderate activity group(10-14 scores, n=16) and severe activity group(≥15 scores, n=19) respectively according to the systemic lupus erythematosus disease activity index(SLEDAI). 25 controls are age and body mass index matched healthy women.2 The frequency of peripheral blood CD4+CD25+Foxp3+ Treg cells was analyzed by flow cytometry and serum leptin was assayed by enzyme linked immunosorbent assay sandwich technique.3 Demographic data, clinical features, laboratory findings, as well as level of serum leptin and frequency of CD4+CD25+Foxp3+ Treg cells among different SLE groups were recorded and analyzed.4 Data were analyzed with SPSS21.0 and Prism 5 software.Results:1 The leptin level of the SLE group was significantly higher than that in control group(P<0.05).2 No differences were observed in serum leptin level among mild activity group, moderate activity group and severe activity group(P>0.05). The leptin level was higher in severe activity group compared with the control(P<0.05). The comparison of serum leptin level between the control group and mild activity and moderate activity group was no difference(P>0.05).3 There was a positive correlation between serum leptin level and SLEDAI in SLE group(r=0.301, P<0.05).4 Leptin level positively correlated with the increasing of high density lipoprotein( P<0.05).5 The frequency of CD4+CD25+Foxp3+ Treg cells of the SLE group was notably lower than that in the control group.(P<0.05).6 No differences were observed in frequency of CD4+CD25+Foxp3+ Treg cells among mild activity group, moderate activity group and severe activity group(P>0.05). The frequency of CD4+CD25+Foxp3+ Treg cells in moderate activity group and severe activity group was lower than the control(P<0.05). The comparison of the frequency of CD4+CD25+Foxp3+ Treg cells between the control group and mild activity group was no difference(P>0.05).7 There was no correlation between the frequency of CD4+CD25+Foxp3+ Treg cells and SLEDAI in SLE patients(r=-0.100, P>0.05).8 There was no correlation between serum leptin level and the frequency of CD4+CD25+Foxp3+ Treg cells in SLE group(r=-0.131, P>0.05).Conclusions:1 SLE patients show leptinemia and leptin level is positively associated with SLE disease activity, suggesting leptin could be a possible monitoring index for active SLE.2 SLE patients with increased high density lipoprotein have higher leptin level and it indicates that leptin participates abnormal lipid metabolism.3 The frequency of CD4+CD25+Foxp3+ Treg cells in peripheral blood of SLE patients is remarkably lower, which does not correlate with SLE disease activity.4 We could not make a conclusion that there is an association between serum leptin level and CD4+CD25+Foxp3+ Treg cells in SLE patients.