Abstract
PURPOSE: CD138 is a cell surface proteoglycan involved in plasma cell survival and cell adhesion, and can be detected in serum via ectodomain shedding. This study aimed to investigate the clinical utility of circulating CD138 at diagnosis in predicting future progression to end-stage kidney disease (ESKD) in patients with microscopic polyangiitis (MPA). MATERIALS AND METHODS: Sixty-five patients newly diagnosed with MPA were included. Antineutrophil cytoplasmic antibody-associated vasculitis-specific indices and clinical and laboratory data were collected. Circulating CD138 levels were measured from stored sera at the time of diagnosis and a cut-off value for predicting ESKD progression was determined using receiver operating characteristic curve analysis. RESULTS: The median circulating CD138 level at diagnosis was 62.8 ng/mL. Circulating CD138 at diagnosis showed positive correlations with the cross-sectional Birmingham Vasculitis Activity Score, Five-Factor Score, erythrocyte sedimentation rate, C-reactive protein level, and baseline serum creatinine level, while demonstrating a negative correlation with serum albumin level. Overall, 12 (18.5%) of 65 patients progressed to ESKD. The incidence of progression to ESKD was higher in patients with circulating CD138 ≥73.3 ng/mL at diagnosis than in those without (relative risk=10.588). Additionally, patients with circulating CD138 ≥73.3 ng/mL at diagnosis exhibited significantly lower ESKD-free survival rates than those without (p=0.002). CONCLUSION: This study demonstrated that circulating CD138 measured at diagnosis has clinical utility as a biomarker for predicting future progression to ESKD in patients with MPA, and incorporating CD138 measurement at diagnosis may assist in identifying high-risk patients and guiding early therapeutic interventions in clinical practice.