Abstract
Kidney injury molecule 1 (KIM-1) is a transmembrane glycoprotein expressed by proximal tubular cells, recognized as an early, sensitive, and specific urinary biomarker for kidney injury. Blood KIM-1 was recently associated with the severity of acute and chronic kidney damage but its value in ANCA-associated vasculitis with glomerulonephritis (ANCA-GN) has not been studied. Thus, we analyzed its expression at ANCA-GN diagnosis and its relationship with clinical presentation, kidney histopathology, and early outcomes.
We assessed KIM-1 levels and other pro-inflammatory molecules (CRP, IL-6, TNF-α, MCP-1 and PTX3) at ANCA-GN diagnosis and after 6 months in patients included in the Maine-Anjou registry, which gathers data patients from four French Nephrology Centers diagnosed since January 2000.
Blood KIM-1 levels were assessed in 58 patients. Levels were elevated at diagnosis and decreased after induction remission therapy. KIM-1 was associated with the severity of renal injury at diagnosis and the need for KRT. In opposition to other pro-inflammatory molecules, KIM-1 correlated with the amount of interstitial fibrosis and tubular atrophy (IF/TA) on kidney biopsy, but not with glomerular involvement. In multivariable analysis, elevated KIM-1 predicted initial eGFR (β = -19 [-31, -7.6], p = 0.002).
KIM-1 appears as a potential biomarker for acute kidney injury and for tubulointerstitial injury in ANCA-GN. Whether KIM-1 is only a surrogate marker for IF/TA or a key immune player in ANCA-GN pathogenesis remain to be determined.
Association between KIM-1 levels and clinical, biological and histological parameters.
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