Aberrant Activation of the WNT/β-Catenin Signaling Pathway in Lupus Nephritis

OBJECTIVE The canonical WNT pathway has been implicated as playing important roles in the pathogenesis of a variety of kidney diseases. Recently, WNT pathway activity was reported to be elevated in the renal tissue of a lupus mouse model. This study aimed to evaluate the potential role of the WNT pathway in the pathogenesis of human lupus nephritis. METHODS The expression of β-catenin was evaluated in renal biopsy specimens from lupus nephritis patients and control kidney tissues by immunohistochemistry and western blotting. Real-time polymerase chain reaction (RT-PCR) was used to detect RNA expression of β-catenin, Dkk-1 and Axin2. Plasma concentrations of Dkk-1 were measured by ELISA. RESULTS Immunohistochemistry and western blotting revealed increased expression of β-catenin in the kidneys of patients with lupus nephritis compared with control kidney tissues (p<0.05), accompanied by an increase in mRNA expression of β-catenin (p<0.01) and axin2 (p<0.05). β-catenin was significantly greater in LN patients without renal interstitial fibrosis compared with those with renal interstitial fibrosis (p<0.01) at the mRNA expression level; the increase in β-catenin mRNA positively correlated with the creatinine clearance rate (Ccr) and negatively correlated with chronicity indices of renal tissue injury. Greater plasma Dkk-1 concentrations were found in LN patients compared with controls (p<0.05). Plasma Dkk-1 concentrations also correlated negatively with anti-dsDNA antibody levels and positively with serum C3 levels. CONCLUSIONS The canonical WNT/β-catenin signaling pathway was activated in lupus nephritis patients, accompanied by an increase in plasma levels of Dkk-1. Altered WNT/β-catenin signaling was related to the pathogenesis of lupus nephritis and might play a role in renal fibrosis.