Interleukin-6: A Proinflammatory Role in Nephritis in Patients with Systemic Lupus Erythematosus

Abstract

Background. Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with a common finding of renal involvement which is related to high incidence of mortality and morbidity. IL-6 is produced by leukocytes and intrinsic kidney cells that affects inflammation, increases mesangial cell proliferation, and also contributes to autoimmunity. Objective. To detect the serum level as well as expression in PBMCs in the blood of IL-6 in SLE patients. Furthermore we compare serum level, as well as expression in PBMCs in the blood of IL-6 of lupus nephritis group versus non-nephritis lupus group and to study its correlation with other variables in SLE patients. Methods. The study was carried on 100 SLE patients, and 50 healthy control subjects. Fifty patients had lupus nephritis and 50 without evidence of lupus nephritis. Serum interleukin 6 (IL6) was measured using the ELISA technique as well as the expression of IL6 mRNA in PBMCs. Serum creatinine, C3, C4 and 24 hours urinary proteins were measured. Lupus activity was assessed using BILAG scoring system. Renal activity was measured using renal activity scoring system. Results. Serum IL6 level and its mRNA expression was significantly high in SLE patients and was higher in lupus nephritis patients than lupus patients without nephritis. IL6 was significantly correlated with renal activity score, 24 hours urinary proteins lowered C3 and C4 level and BILAG score. Conclusion. Serum IL-6 level and its mRNA expression is elevated in SLE patients as well as lupus nephritis patients. This was found to be linked with SLE disease activity in general and renal involvement in particular.