Intra-renal expression of B-cell activating factor (BAFF) in active proliferative lupus nephritis.

Asmaa Beltagy; Raghda Saad Zaghloul Taleb; Maram Allam; Ragaa Abd El-Kader; Amira Al-Girby Al-Girby; Abeer Abdelati

Asmaa Beltagy Faculty of Medicine, Alexandria University
Raghda Saad Zaghloul Taleb Department of Clinical and Chemical Pathology, Faculty of Medicine, Alexandria University, Egypt.
Maram Allam Department of Pathology, Faculty of Medicine, Alexandria University, Egypt.
Ragaa Abd El-Kader Department of Internal Medicine, Rheumatology Unit, Faculty of Medicine, Alexandria University, Egypt.
Amira Al-Girby Al-Girby Department of Internal Medicine, Rheumatology Unit, Faculty of Medicine, Alexandria University, Egypt.
Abeer Abdelati Department of Internal Medicine, Rheumatology Unit, Faculty of Medicine, Alexandria University, Egypt.

Keywords: Lupus, lupus nephritis, BAFF

Abstract

Background: Systemic lupus erythematosus (SLE) is an auto-immune disease that affects various body systems. Approximately half of SLE patients develop lupus nephritis (LN). Lupus nephritis is classified into six classes, with classes III and IV being the most proliferative. Lupus nephritis severity and prognosis can be influenced by several biomarkers. Some of these biomarkers are used as therapeutic targets, including the B-cell activating factor (BAFF), which plays a fundamental role in SLE pathogenesis. A BAFF-targeted immunoglobulin G, Belimumab, has been approved by the FDA as an add-on treatment for active proliferative LN (pLN). The aim of the study was to explore the role of intra-renal BAFF expression as a potential severity stratifying tool and a predictor of response. Materials & Methods: Our study was retrospective, 40 patients who were diagnosed as active pLN were recruited after completion of induction therapy. All patients at baseline were clinically assessed by evaluating renal, serological and histopathological parameters. After 6 months of the start of induction therapy, follow-up response parameters were evaluated. Renal biopsies were extracted from the pathology archive and gene expression of BAFF was quantified using real-time PCR. Results: After follow-up, 21 patients were considered as early responders(eR) according to the reduction of urinary protein creatinine ratio and stabilization of the estimated glomerular filtration rate. Baseline intra-renal BAFF gene expression was higher in non-responders (eNR) than responders (1.7 vs 1.48, p=0.741), although that was statistically non-significant. We could not find a significant correlation between BAFF gene expression and pertinent baseline or follow-up response parameters. Conclusion: Although median BAFF expression was higher in eNR than eR, we could not conclude a definite relation between intra-renal BAFF and other severity assessments or response parameters and could not be solely used as a stratifying biomarker.