Advanced oxidation protein products as a biomarker of cutaneous lupus erythematosus complicated by nephritis: a case-control study.

Oxidative stress is involved in the pathogenesis of lupus nephritis (LN). The current study investigated the significance of advanced oxidation protein products (AOPPs) as a biomarker of LN in patients with cutaneous lupus erythematosus. Ninety-two patients who initially presented with systemic lupus erythematosus were divided into the LN- and LN+ groups. Serum AOPP levels were determined, and the association between AOPP levels and LN was investigated in a case-control study. In the LN+ group, patients with higher AOPP levels exhibited higher levels of dsDNA and proteinuria but lower levels of eGFR and complement C3 compared to those in patients with lower AOPP levels. A multivariable logistic regression model showed that the AOPP level was an independent risk factor for LN. The risk of nephritis specifically increased 24% for each 10 μM increase in AOPP (95% confidence interval, 1.166-1.915, P = 0.030). In contrast, neither elevated dsDNA level nor decreased complement C3 level was an independent risk factor for LN. Higher serum AOPP levels were associated with an increased risk of LN. Therefore, future studies are warranted to determine the potential clinical value of this novel biomarker.