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Abstract: FR-PO653

Interstitial ANCA-Associated Vasculitis Associates With Severe Kidney Injury Independent of Glomerulonephritis

Session Information

Category: Glomerular Diseases

  • 1303 Glomerular Diseases: Clinical‚ Outcomes‚ and Trials

Authors

  • Tampe, Desiree, University Medical Center Göttingen, Göttingen, Germany
  • Hakroush, Samy, University Medical Center Göttingen, Göttingen, Germany
  • Tampe, Bjoern, University Medical Center Göttingen, Göttingen, Germany
Background

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis affecting multiple organ systems, including the kidney. Small vessels in the kidney include small-sized arteries (interlobular artery, afferent and efferent arteriole), capillaries (glomerular and peritubular capillary) and venules. Although crescentic ANCA glomerulonephritis (GN) is a common histological finding reflecting glomerular small vessel vasculitis, it is reasonable that manifestation of AAV could also contribute to interstitial small vessel vasculitis.

Methods

A total number of 49 kidney biopsies with confirmed renal involvement of AAV were retrospectively included, a renal pathologist evaluated all biopsies and was blinded to clinical data collection and analysis.

Results

Among all active and chronic tubulointerstitial lesions analogous to the Banff scoring system, the only association between severe kidney injury requiring kidney replacement therapy (KRT) was observed for interstitial vasculitis in AAV reflected by peritubular capillaritis (ptc, p=0.0002) and arteritis (v, p=0.0069), affecting 5/49 (10.2%) and 11/49 (22.4%) of renal biopsies, respectively. 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 KRT was equal in both groups, suggesting a distinct association with acute decline of kidney function at disease onset.

Conclusion

Taken together, by using the Banff scoring system we here expand our current knowledge of renal interstitial lesions in AAV revealing peritubular capillaritis and arteritis as important histological alterations associated with severe kidney injury in a considerable subset of AAV. Furthermore, our findings that interstitial vasculitis did not correlate with crescentic ANCA GN implicate that the characteristics of each vasculitis manifestation are independent and could further improve our understanding of mechanisms contributing to renal injury.