Urinary Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK) As a Marker for Lupus Nephritis Activity

BACKGROUND Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by auto antibodies directed against nuclear antigens and causing a variety of clinical and laboratory abnormalities and involving multiple organs, causing significant morbidity and mortality. Lupus nephritis (LN) is one of the most serious SLE complications since it is the major predictor of poor prognosis. For LN, the search for an accurate and reliable biomarker is particularly pressing since the only truly reliable method to evaluate LN in current practice is by performing a kidney biopsy, an invasive procedure. Therefore, the search for a lupus biomarker has been especially intense. OBJECTIVE The aim of this study is to evaluate the urinary TWEAK (uTWEAK) as a biomarker for lupus nephritis activity. METHODS This study included 40 SLE patients, who were admitted to the inpatient of Nephrology unit of Internal Medicine department and Rheumatology and Rehabilitation department, faculty of medicine, Zagazig university. All individuals in this study were divided into 2 groups Group I (20 patients) patients with active renal disease and having a renal systemic lupus erythematosus disease activity index (rSLEDAI) score of 4 (i. e. , at least 1 abnormal result for renal parameters) and Group II (20 patients) patients with inactive renal disease (patients with history of LN whose disease became quiescent for at least 6 months after treatment and having a rSLEDAI score of 0 (i. e. they did not have, at the time of the visit, pyuria, proteinuria, hematuria or urinary casts). All patients included in the study were subjected to proper history taking and thorough medical examination in addition to laboratory investigations like, complete urine analysis, blood urea, serum creatinine, liver function tests, ESR and 24 hours urinary proteins estimation, ANA, AdsDNA antibodies, quantitative determination of serum C3 and C4 and kidney biopsy and uTWEAK estimation, plus abdominal sonography. RESULTS A statistically significant difference regarding the mean uTWEAK level and the mean rSLEDAI was found between the 2 groups (P