THU0385 Urinary inflammatory cells reflect histopathological kidney injury in patients with lupus nephritis
Authors: Y. Wada, M. Sudo, M. Sakatsume, T. Kuroda, M. Nakano, I. Narita
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Lupus nephritis (LN) is one of the common manifestations of systemic lupus erythematosus (SLE), and is considered to be a very important factor influencing the course of the disease. Although kidney biopsy is the gold standard for defining the histopathologic class of LN, it is an invasive procedure sometimes associated with a risk of bleeding and thrombotic events; furthermore, repeated biopsies are not always applicable in clinical practice. We have already reported that, in patients with glomerulonephritis, inflammatory cells such as T cells and macrophages appear in the urine when there are accompanying signs of active cellular infiltration such as cellular crescent formation and diffuse interstitial cell infiltration, but not when active inflammatory lesions are absent. <h3>Objectives</h3> To assess the utility of urinary inflammatory cell analysis in patients with LN by examining the correlations between the numbers of urinary inflammatory cells and renal histopathological findings. <h3>Methods</h3> Twenty-six patients with SLE, who had been referred to Niigata University Hospital between 2004 and 2017 and diagnosed as having LN by percutaneous kidney biopsy, were recruited for this study. Flow-cytometric analysis of urinary inflammatory cells was performed for each subject at the time of admission for kidney biopsy. 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 histopathological findings of kidney biopsy specimens for each subject were classified according to the 2003 International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification of LN. In addition, they were also evaluated for glomerular and interstitial lesions such as mesangial cell/matrix proliferation, endocapillary hypercellularity, crescent formation, and interstitial cell infiltration and fibrosis. The severity of each lesion was scored from 0 to 4, and the numbers of urinary inflammatory cells were analysed by Spearman's rank correlation coefficient to determine the relationships among these scores. Next, the patients were divided into two groups according to whether the total number of urinary inflammatory cells was significantly increased (more than 120 cells/ml; positive group, n=12) or not (negative group, n=14), and the severities of the histopathological lesions were compared between the two groups. <h3>Results</h3> Disease severity in terms of the ISN/RPS classifications was positively correlated with the severity of mesangial cell and matrix proliferation, cellular crescent formation, and duplication of the glomerular basement membrane. In addition to these four factors, the numbers of CD3-positive and CD14-positive cells were also positively correlated with adhesion, endocapillary hypercellularity, interstitial inflammatory cell infiltration, and interstitial fibrosis. The severity scores for adhesion, endocapillary hypercellularity, cellular and fibrous crescent formation, duplication, and interstitial cell infiltration were significantly higher in the positive group than in the negative group. <h3>Conclusions</h3> Analysis of urinary immune cells reflects the histopathological features of kidney biopsy specimens from patients with LN. <h3>Reference</h3> [1] Sakatsume M, et al. J Am Soc Nephrol2001;12(12): 2636–44. <h3>Disclosure of Interest</h3> None declared