Urinary Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (uTWEAK) as a biomarker for lupus nephritis activity and its correlation with histolopathological findings of renal biopsy

Background: Lupus nephritis (LN) remains the strongest predictor of overall patient morbidity and mortality in systemic lupus erythematosus (SLE). Aim of the work: To evaluate urinary Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (uTWEAK) as a biomarker for LN activity and its correlation with histological findings of renal biopsy. Patients and methods: 42 SLE patients were recruited and 20 control. SLE disease activity index (SLEDAI) and rSLEDAI were calculated. uTWEAK was estimated by ELISA. Patients were divided into those with (n = 22) and without (n = 20) active renal disease. Renal biopsy was perfromed to those with active LN. The activity index (AI) and Chronicity Index (CI) were scored. Results: The 42 patients were 35 (83.3%) females and 7 (16.7%) males (F:M 5:1) with a mean age of 31.3 ± 11.1 years (18–50 years). There was a significant difference in the uTWEAK levels between patients with active LN, inactive LN and control (7 ± 4.5, 2.5 ± 1.4 and 0.3 ± 0.4 ng/mg Cr respectively) (p < 0.0001). uTWEAK significantly correlated with rSLEDAI (r = 0.47, p = 0.02), and with AI (r = 0.47, p = 0.03), hypercellularity (r = 0.47, p = 0.03), fibrinoid necrosis (r = 0.46, p = 0.03), cellular crescent (r = 58, p = 0.004) and tubular atrophy (r = 48, p = 0.02) in renal biopsy of active LN patients. uTWEAK was a significant independent predictor of LN (p = 0.003) with a sensitivity of 77.3% and specificity of 90%. Conclusion: uTWEAK might clearly be a candidate marker for LN activity and may replace invasive renal biopsy, potentially serving as a helpful biomarker in the clinical follow-up. It could represent an interesting biological tool if the diagnosis of a flare is in doubt. Keywords: SLE, Lupus nephritis, rSLEDAI, Renal biopsy, uTWEA