Potential role of circulating miRNA-146a and serum kallikrein 1 as biomarkers of renal disease in biopsy-proven lupus nephritis patients

Abstract

Aim of the workTo evaluate the performance of circulating miR-146a and serum kallikrein1 (KLK1) as biomarkers for detecting disease activity and distinguishing histopathological changes associated with lupus nephritis (LN). Patients and methods90 systemic lupus erythematosus (SLE) patients (44 with active non-renal disease and 46 with LN) were examined for relative expression levels of circulating miR-146a, assessed by reverse transcription quantitative real-time PCR (RT-qPCR) and serum KLK1 levels, measured by ELISA. SLE disease activity was assessed using SLEDAI-2 k. Receiver operating characteristic curve was employed to examine the diagnostic performance of both biomarkers and established conventional laboratory parameters of renal function with specific renal histologic features seen in LN. As well, 40 apparently healthy control subjects were enrolled. ResultsCirculating miR-146a levels were significantly lower (p < 0.01), while serum KLK1 levels were significantly higher (p < 0.01) in active LN patients compared to active non-renal and controls. miR-146a levels negatively correlated with serum creatinine, Albumin/Creatinine and SLEDAI-2 k (p ≤ 0.01), while serum KLK1 significantly correlated with serum creatinine, Albumin/Creatinine and C3 (p ≤ 0.05) and inversely with miR-146a (p = 0.002). Both circulating miR-146a and KLK1 revealed an outstanding performance in predicting renal activity among SLE patients with an AUC of 0.949 and 0.947 respectively. In active LN patients, KLK1 and miR-146a exhibited good ability in differentiating proliferative from non-proliferative LN (AUC 0.73, 0.65 respectively), and in predicting biopsy activity index ≥7, surpassing conventional disease measures. ConclusionCirculating miR-146a and serum KLK1 are potential biomarkers for LN that could compete with invasive renal biopsy. Independent validation is warranted.