Background (LN)Lupus nephritis is a major risk for overall morbidity and mortality in SLE (Systemic lupus erythromatosis), and despite potent anti-inflammatory and immunosuppressive therapies still ends in Chronic Kidney Disease(CKD) or End Stage Renal Disease (ESRD) for too many patients. Renalase is a novel, kidney secreted cytokine-like protein that promotes cell survival.

Aim of the work studying the relationship between level of Human Serum Renalase (RNLS) with LN and its role in the disease activity and progression.

Methods For The current cross-sectional study 23 healthy controls and 48 patients with LN were screened and 30 subjects were selected These patients were subdivided into two equal groups according to disease activity measured by SLEDAI (SLE Disease Activity Index). Human Serum Renalase (RNLS) concentration was measured by a highly sensitive, commercial sandwich enzyme immunoassay which uses (RNLS) antibody to capture Renalase from serum. Assessment before and after treatment was done for 17 patients who received prednisone and immunosuppressive therapy were recruited and followed up for three months to evaluate the serum renalase levels before and after treatment.

Results The level of renalase was significantly higher in LN patients compared to healthy controls, (P value<0.001). Moreover, patients with active LN had higher serum renalase levels compared to patients with inactive LN( P value<0.005) Serum renalase levels were positively correlated with SLEDAI, 24 hour urine protein excretion, ds-DNA and ESR and CRP but inversely correlated with serum C3 and the class (especially in prolferative type (Class III, IV, more than class V). Renalase amounts decreased significantly after three-months of standard therapy. Also we found there is insignificant difference of renlase level according to treatment by MMF(mycophenolate mofetil) and Cyclophosphamide during and after activity (P value=0.655, 0.550)

Conclusions Serum renalase levels were correlated with disease activity in LN. Serum renalase might serve as a potential indicator for disease activity in LN.