Clinicopathological significance of glomerular capillary IgA deposition in childhood IgA nephropathy
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ORIGINAL ARTICLE
Clinicopathological significance of glomerular capillary IgA deposition in childhood IgA nephropathy Yuko Shima 1 & Koichi Nakanishi 2 & Hironobu Mukaiyama 1 & Yu Tanaka 1 & Takuzo Wada 1 & Ryojiro Tanaka 3 & Hiroshi Kaito 3 & Kandai Nozu 4 & Mayumi Sako 5 & Kazumoto Iijima 4 & Norishige Yoshikawa 6 Received: 22 May 2020 / Revised: 26 July 2020 / Accepted: 9 September 2020 # IPNA 2020
Abstract Background IgA nephropathy (IgAN) is characterized by predominant mesangial IgA deposition. Some patients with IgAN demonstrate IgA deposition in glomerular peripheral capillaries (cap-IgA). The clinicopathological significance of cap-IgA remains incompletely investigated in children. Methods We retrospectively analyzed 503 consecutive cases of biopsy-proven childhood IgAN between July 1976 and June 2013 to compare clinical and pathological features between IgAN patients with and without cap-IgA. Results Among the 503 patients, 30 (6.0%) had cap-IgA. We found significant differences in proteinuria (2.0 vs. 0.5 g/day/m2, p < 0.0001), time from onset to kidney biopsy (2.2 vs. 8.3 months, p < 0.0001), and rate of proteinuria remission after treatment (23.3% vs. 48.0%, p = 0.007) between both groups. Pathological analysis revealed significant differences in M1 (83.3% vs. 56.0%, p = 0.002), ratio of subendothelial electron dense deposits (EDDs, 58.6% vs. 16.5%, p < 0.0001) and subepithelial EDDs (48.3% vs. 16.5%, p = 0.0001), and glomerular basement membrane (GBM) lysis (58.6% vs. 27.1%, p = 0.0006) between both groups. More than half of cap-IgA patients (17/30, 56.7%), whereas only 26.2% of non-cap-IgA patients (124/473), were treated with immunosuppressive treatments. Six of 30 cases (20%) with cap-IgA reached glomerular filtration rate (GFR) categories G3a–G5 (estimated GFR < 60 ml/min/1.73 m2) at most recent observation (mean observation period: 7.0 ± 4.0 years). According to Kaplan-Meier analysis, patients with cap-IgA had significantly lower kidney survival curves than non-cap-IgA patients (72.8% vs. 97.2% at 10 years, p < 0.0001). Conclusions Cap-IgA is associated with acute inflammation with GBM changes, resulting in refractory heavier proteinuria. CapIgA may represent a poor prognostic factor. Keywords Immunofluorescence . Capillary IgA deposition . IgAN . Kidney failure . School screening programs . Electron dense deposits . Children
* Koichi Nakanishi [email protected] 1
Department of Pediatrics, Wakayama Medical University, Wakayama City, Wakayama, Japan
2
Department of Pediatrics, Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, 207 Uehara Nishihara-cho, Nakagami-gun, Okinawa 903-0125, Japan
3
Department of Nephrology, Hyogo Prefectural Kobe Children’s Hospital, Kobe, Hyogo, Japan
4
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
5
Division for Clinical Trials, Clinical Research Center, National Center for Child Health and Development, Tokyo, Japan
6
Clinical Research Center, Takatsuki Gener
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