INTERSTITIAL ANCA-ASSOCIATED VASCULITIS ASSOCIATES WITH SEVERE KIDNEY INJURY INDEPENDENT OF GLOMERULONEPHRITIS
Abstract: POS1437
Authors: B. Tampe et al.
Crescentic ANCA glomerulonephritis (GN) is the common histological finding reflecting glomerular small vessel vasculitis. However, small vessels in the kidney include small-sized arteries (interlobular artery, afferent and efferent arteriole), capillaries (glomerular and peritubular capillary) and venules. To what extent extra-glomerular small vessels contribute to kidney damage and function loss is unclear.
Key Content:
49 kidney biopsies with confirmed renal involvement of AAV were analyzed. Interstitial vasculitis in association with requirement of renal replacement therapy (RRT) was scored. Among all active and chronic tubulointerstitial lesions, the only association between severe kidney injury requiring RRT was observed for interstitial vasculitis in AAV reflected by peritubular capillaritis (ptc, p=0.0002) and arteritis (v, p=0.0069).
Since it is known that severe deterioration of kidney function also correlates with crescentic ANCA GN, glomerular and tubulointerstitial lesions were directly compared: The fraction of normal glomeruli was inversely associated with interstitial fibrosis and inflammation, whereas glomerular crescents were associated with interstitial inflammation and tubulitis. In contrast, global glomerular sclerosis associated with less interstitial inflammation but correlated with interstitial fibrosis and tubular atrophy, confirming established mechanism that chronic glomerular injury leads to tubular atrophy and interstitial fibrosis. Interestingly, no association between interstitial vasculitis (ptc and v correlating with severe kidney injury) and any glomerular lesion in ANCA GN (also correlating with severe kidney injury) was observed, thereby confirming that interstitial vasculitis contributes to severe kidney injury independent of ANCA GN. By contrast, short-term renal recovery from RRT was equal in both groups, suggesting a distinct association with acute decline of kidney function at disease onset.
Relevance:
Peritubular capillaritis and arteritis are important histological alterations associated with severe kidney injury in a considerable subset of AAV. The data suggest that interstitial vasculitis and crescentic ANCA GN are independent mechanism contributing to renal injury.
