Hirokazu Marumoto1, Nobuo Tsuboi1, Vivette D D'Agati2, Takaya Sasaki1, Yusuke Okabayashi1, Kotaro Haruhara1, Go Kanzaki1, Kentaro Koike1, Akira Shimizu3, Tetsuya Kawamura1, Andrew D Rule4, John F Bertram5, Takashi Yokoo1. 1. Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan. 2. Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York. 3. Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan. 4. Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota. 5. Department of Anatomy and Developmental Biology and Biomedical Discovery Institute, Monash University, Melbourne, Australia.
Abstract
Background: Single-nephron dynamics in progressive IgA nephropathy (IgAN) have not been studied. We applied novel methodology to explore single-nephron parameters in IgAN. Methods: Nonglobally sclerotic glomeruli (NSG) and globally sclerotic glomeruli (GSG) per kidney were estimated using cortical volume assessment via unenhanced computed tomography and biopsy-based stereology. Estimated single-nephron GFR (eSNGFR) and single-nephron urine protein excretion (SNUPE) were calculated by dividing eGFR and UPE by the number of NSG. Associations with CKD stage and clinicopathologic findings were cross-sectionally investigated. Results: This study included 245 patients with IgAN (mean age 43 years, 62% male, 45% on renin-angiotensin aldosterone system [RAAS] inhibitors prebiopsy) evaluated at kidney biopsy. CKD stages were 10% CKD1, 43% CKD2, 19% CKD3a, 14% CKD3b, and 14% CKD4-5. With advancing CKD stage, NSG decreased from mean 992,000 to 300,000 per kidney, whereas GSG increased from median 64,000 to 202,000 per kidney. In multivariable models, advancing CKD stage associated with lower numbers of NSG, higher numbers of GSG, and lower numbers of GSG + NSG, indicating potential resorption of sclerosed glomeruli. In contrast to the higher mean glomerular volume and markedly elevated SNUPE in advanced CKD, the eSNGFR was largely unaffected by CKD stage. Lower SNGFR associated with Oxford scores for endocapillary hypercellularity and crescents, whereas higher SNUPE associated with segmental glomerulosclerosis and tubulointerstitial scarring. Conclusions: SNUPE emerged as a sensitive biomarker of advancing IgAN. The failure of eSNGFR to increase in response to reduced number of functioning nephrons suggests limited capacity for compensatory hyperfiltration by diseased glomeruli with intrinsic lesions.
Background: Single-nephron dynamics in progressive IgA nephropathy (IgAN) have not been studied. We applied novel methodology to explore single-nephron parameters in IgAN. Methods: Nonglobally sclerotic glomeruli (NSG) and globally sclerotic glomeruli (GSG) per kidney were estimated using cortical volume assessment via unenhanced computed tomography and biopsy-based stereology. Estimated single-nephron GFR (eSNGFR) and single-nephron urine protein excretion (SNUPE) were calculated by dividing eGFR and UPE by the number of NSG. Associations with CKD stage and clinicopathologic findings were cross-sectionally investigated. Results: This study included 245 patients with IgAN (mean age 43 years, 62% male, 45% on renin-angiotensin aldosterone system [RAAS] inhibitors prebiopsy) evaluated at kidney biopsy. CKD stages were 10% CKD1, 43% CKD2, 19% CKD3a, 14% CKD3b, and 14% CKD4-5. With advancing CKD stage, NSG decreased from mean 992,000 to 300,000 per kidney, whereas GSG increased from median 64,000 to 202,000 per kidney. In multivariable models, advancing CKD stage associated with lower numbers of NSG, higher numbers of GSG, and lower numbers of GSG + NSG, indicating potential resorption of sclerosed glomeruli. In contrast to the higher mean glomerular volume and markedly elevated SNUPE in advanced CKD, the eSNGFR was largely unaffected by CKD stage. Lower SNGFR associated with Oxford scores for endocapillary hypercellularity and crescents, whereas higher SNUPE associated with segmental glomerulosclerosis and tubulointerstitial scarring. Conclusions: SNUPE emerged as a sensitive biomarker of advancing IgAN. The failure of eSNGFR to increase in response to reduced number of functioning nephrons suggests limited capacity for compensatory hyperfiltration by diseased glomeruli with intrinsic lesions.
Authors: D A Maddox; C M Bennett; W M Deen; R J Glassock; D Knutson; T M Daugharty; B M Brenner Journal: J Clin Invest Date: 1975-02 Impact factor: 14.808
Authors: Ian S D Roberts; H Terence Cook; Stéphan Troyanov; Charles E Alpers; Alessandro Amore; Jonathan Barratt; Francois Berthoux; Stephen Bonsib; Jan A Bruijn; Daniel C Cattran; Rosanna Coppo; Vivette D'Agati; Giuseppe D'Amico; Steven Emancipator; Francesco Emma; John Feehally; Franco Ferrario; Fernando C Fervenza; Sandrine Florquin; Agnes Fogo; Colin C Geddes; Hermann-Josef Groene; Mark Haas; Andrew M Herzenberg; Prue A Hill; Ronald J Hogg; Stephen I Hsu; J Charles Jennette; Kensuke Joh; Bruce A Julian; Tetsuya Kawamura; Fernand M Lai; Lei-Shi Li; Philip K T Li; Zhi-Hong Liu; Bruce Mackinnon; Sergio Mezzano; F Paolo Schena; Yasuhiko Tomino; Patrick D Walker; Haiyan Wang; Jan J Weening; Nori Yoshikawa; Hong Zhang Journal: Kidney Int Date: 2009-07-01 Impact factor: 10.612