Micro-RNA analysis of renal biopsies in human lupus nephritis demonstrates up-regulated miR-422a driving reduction of kallikrein-related peptidase 4

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2016-10, Vol.31 (10), p.1676-1686
• Main Authors: Krasoudaki, Eleni, Banos, Aggelos, Stagakis, Elias, Loupasakis, Konstantinos, Drakos, Elias, Sinatkas, Vaios, Zampoulaki, Amalia, Papagianni, Aikaterini, Iliopoulos, Dimitrios, Boumpas, Dimitrios T, Bertsias, George K
• Format: Article
• Language: English
• Subjects: Animals; Biopsy; Case-Control Studies; Gene Expression Profiling; Gene Expression Regulation; Humans; Kallikreins - genetics; Kallikreins - metabolism; Kidney - metabolism; Kidney - pathology; Lupus Nephritis - genetics; Lupus Nephritis - metabolism; Lupus Nephritis - pathology; Lupus Nephritis - surgery; Mice; MicroRNAs - genetics; Signal Transduction; Up-Regulation
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfv374

Aberrancies in gene expression in immune effector cells and in end-organs are implicated in lupus pathogenesis. To gain insights into the mechanisms of tissue injury, we profiled the expression of micro-RNAs in inflammatory kidney lesions of human lupus nephritis (LN). Kidney specimens were from patients with active proliferative, membranous or mixed LN and unaffected control tissue. Micro-RNAs were quantified by TaqMan Low Density Arrays. Bioinformatics was employed to predict gene targets, gene networks and perturbed signaling pathways. Results were validated by transfection studies (luciferase assay, real-time PCR) and in murine LN. Protein expression was determined by immunoblotting and immunohistochemistry. Twenty-four micro-RNAs were dysregulated (9 up-regulated, 15 down-regulated) in human LN compared with control renal tissue. Their predicted gene targets participated in pathways associated with TGF-β, kinases, NF-κB, HNF4A, Wnt/β-catenin, STAT3 and IL-4. miR-422a showed the highest upregulation (17-fold) in active LN and correlated with fibrinoid necrosis lesions (β = 0.63, P = 0.002). In transfection studies, miR-422a was found to directly target kallikrein-related peptidase 4 (KLK4) mRNA. Concordantly, KLK4 mRNA was significantly reduced in the kidneys of human and murine LN and correlated inversely with miR-422a levels. Immunohistochemistry confirmed reduced KLK4 protein expression in renal mesangial and tubular epithelial cells in human and murine LN. KLK4, a serine esterase with putative renoprotective properties, is down-regulated by miR-422a in LN kidney suggesting that, in addition to immune activation, local factors may be implicated in the disease.