AB0539 URINARY INFLAMMATORY CELL ANALYSIS REFLECTS THE RENAL HISTOPATHOLOGY IN ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY-ASSOCIATED VASCULITIS
Authors: Y. Wada, M. Sudo, D. Kobayashi, T. Kuroda, I. Narita
Journal: Annals of the Rheumatic Diseases (2020)

Background: The anti-neutrophil cytoplasmic autoantibody (ANCA)- associated vasculitides (AAVs) include microscopic polyangiitis (MPA), granulomatosis with polyangitis (GPA), and eosinophilic granulomatosis with polyangitis (EGPA). These small-vessel vasculitides are characterized by necrotizing inflammation of the vessel wall, particularly affecting small arteries, arterioles, and capillaries in systemic organs, and the kidney is one of the most frequently involved organs. Although kidney biopsy is necessary for deciding the therapeutic protocol, it is invasive and is sometimes hard to perform biopsy because of patient’s severe general condition. We have already reported that T cells and macrophages appear in the urine of patients with glomerulonephritis, accompanied by active cellular infiltration such as cellular crescent formation and diffuse interstitial cell infiltration, but not in the urine of patients with glomerulonephritis without the active inflammatory lesions. Objectives: In this study, we examined the utility of urinary inflammatory cell analysis for accessing kidney histopathological findings in AAVs. Methods: This was a cross-sectional, retrospective chart study. Thirty-six AAV patients who had been referred to Niigata University Hospital between 2002 and 2018, and performed percutaneous kidney biopsy and urinary inflammatory cell analysis, were participated in this study. Thirty-two patients had MPA, and 4 had GPA. The kidney biopsy findings were classified into Berden’s classification (a method to categorize glomerular lesions into four classes) and Neumann’s classification (a method to evaluate glomerular, tubulo-interstitial, and vascular lesions by using activity indexes and chronicity indexes). Flow-cytometric analysis of urinary inflammatory cells was performed for each subject. Numbers of urinary T cells or macrophages were determined by multiplying the number of viable cells in the gated mononuclear cell region in each sample by the percentage of urinary CD3-positive or CD14-positive cells in the population, respectively. The correlations between the results of both methods and the numbers of urinary inflammatory cells were examined using Kruskal-Wallis test and Spearmann’s rank correlation coefficient. A p-value of &lt;0.05 was taken to denote statistical significance. Results: The numbers of urinary inflammatory cells showed a trend of increase in crescentic category without statistical significance in Berden’s classification. Meanwhile, activity indexes had significant positive correlations with the number of urinary CD3-positive cells (r = 0.541, p = &lt;0.001), CD14-positive cells (r = 0.354, p = 0.034), and total inflammatory cells (r = 0.449, p = 0.006) in Neumann’s classification. Conclusion: The numbers of urinary inflammatory cells reflect the active lesions of kidney histopathological findings, and these results indicate the usefulness of urinary inflammatory cell analysis for assessment of kidney biopsy findings in patients with AAVs. References: [1]Berden AE, et al. J Am Soc Nephrol. 2010 Oct;21(10):1628-36. 2) Neumann I, et al. Nephrol Dial Transplant. 2005 Jan;20(1):96-104. Disclosure of Interests: None declared