Expression of B-cell activating factor (BAFF) in proliferative lupus nephritis, revisited

Abstract

ABSTRACT Introduction Systemic Lupus Erythematosus, an autoimmune disease, can target various organs of the human body. Lupus nephritis (LN) is a major complication affecting almost half of all SLE patients, with classes “III and IV” being the most aggressive. The severity and prognosis of LN can be influenced by different biomarkers, some of which are used as therapeutic targets. One such target is the B-cell activating factor (BAFF), a key figure in the pathophysiology of SLE. New add-on treatments have emerged in the treatment of LN targeting BAFF as well as other pathways. Assortment of patients to suitable treatment combinations needs more precision using guiding markers. Methods This prospective study aims to explore BAFF-expression in patients with active-proliferative LN and its possible association with the response after induction therapy. Peripheral blood mononuclear cells (PBMC) and renal tissue samples (if applicable) were collected from participants before the initiation of induction treatment. RNA was extracted, and the expression levels of BAFF-mRNA were measured using quantitative real-time polymerase chain reaction. Clinical and laboratory data, including disease activity indices and renal functions, were recorded at baseline and 6-months after the commencement of the induction treatment. Results The study included 24 patients,14 responders and 10 non-responders. At baseline, median PBMC BAFF-mRNA expression was nearly identical in responders and non-responders. Renal BAFF-expression was found to be higher in non-responders, although non-significant (p = 0.21). Contrary to PBMC BAFF expression, renal BAFF-mRNA was negatively correlated with baseline glomerular filtration rate and with the primary endpoint of response, which was reduction of proteinuria to≥50% of baseline (p = 0.07). Conclusions Renal BAFF expression could be a better representative of severity and therapeutic response than blood expression. We acknowledge that the use of BAFF expression as a predictive for early refractoriness to therapy in LN is not yet conclusive.