Reduced number of endothelial progenitor cells is predictive of early relapse in anti-neutrophil cytoplasmic antibody-associated vasculitis.

Abstract

OBJECTIVES: ANCA-associated vasculitis (AAV) is an inflammatory disorder of small- to medium-sized vessels with relapsing/remitting progression. Microvascular endothelial injury is a major feature of AAV. Circulating endothelial progenitor cells (EPCs) may provide an endogenous repair mechanism to counteract ongoing endothelial damage. We hypothesized that decreased capacity for endothelial regeneration paralleled by low EPC numbers could increase the risk of relapse in patients with AAV. METHODS: The number of circulating EPCs was determined by a colony-forming assay in a cohort of 41 patients with AAV. The patients were stratified into three subgroups according to the initial EPC count (low, medium and high) and prospectively followed. The primary goal was to determine the association between baseline EPC level and the time to the first relapse of the disease. RESULTS: A total of 19 (46%) patients relapsed during the study period. The cumulative relapse-free survival increased stepwise across three increasing baseline levels of EPCs (P = 0.013). EPC levels were not predictive of progression of renal disease, number of organs involved or death from any cause. CONCLUSION: Low numbers of EPCs are associated with increased propensity for early relapse of AAV.