Nineteen healthy volunteers served as controls.Urinary Dkk-3 concentrations at diagnosis were quantified using ELISA (DY1118, R multiple comparisons with the Kruskal-Wallis test; and correlations with Spearman's rank correlation test.Results: Urinary Dkk-3 levels were markedly higher in MPA patients than in healthy controls (9.5 1.2 vs. 1.0 0.1 ng/mL; p < 0.001).Urinary Dkk-3 correlated significantly with serum creatinine, estimated glomerular filtration rate (eGFR), C-reactive protein (CRP), urinary neutrophil gelatinase-associated lipocalin (NGAL), 2microglobulin, kidney injury molecule-1 (KIM-1), and N-acetyl--Dglucosaminidase (NAG).No correlation was observed with urinary protein, urinary sediment, or MPO-ANCA levels.Urinary Dkk-3 was not associated with the EUVAS classification, tubular atrophy, or interstitial fibrosis.Immunohistochemistry showed no Dkk-3 expression in normal kidneys, whereas in MPA kidneys, Dkk-3 was localized to proximal tubular epithelial cells and infiltrating interstitial cells.Double immunofluorescence revealed co-localization of Dkk-3 with CD68-positive macrophages but not with CD3-positive T cells.Moreover, urinary Dkk-3 levels decreased following corticosteroid therapy.Conclusion: Urinary Dkk-3 correlated with renal function parameters but not with disease activity markers such as MPO-ANCA, proteinuria, or urinary sediment, and declined after corticosteroid treatment.Although urinary Dkk-3 has been associated with interstitial fibrosis in acute kidney injury, no such relationship was observed in MPA.The localization of Dkk-3 in CD68-positive macrophages suggests that urinary Dkk-3 reflects intrarenal inflammation rather than chronic structural damage.These findings indicate that urinary Dkk-3 may serve as a non-invasive biomarker of renal inflammation in MPA.Given that renal biopsy is often contraindicated in elderly patients with severe comorbidities, urinary Dkk-3 measurement may provide a practical tool for assessing disease activity and treatment response.I have no potential conflict of interest to disclose.I did not use generative AI and AI-assisted technologies in the writing process.
Oh et al. (Wed,) studied this question.