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Kuno H, Kanzaki G, Sasaki T, Okabayashi Y, Haruhara K, Yokote S, Koike K, Ueda H, Tsuboi N, Yokoo T. Fractional excretion of total protein predicts renal prognosis in Japanese patients with primary membranous nephropathy. Clin Kidney J 2024; 17:sfae071. [PMID: 38699483 PMCID: PMC11063954 DOI: 10.1093/ckj/sfae071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Indexed: 05/05/2024] Open
Abstract
Background Primary membranous nephropathy (pMN) is one of the most common types of glomerulonephritis, with a third of patients progressing to renal insufficiency. Various prognostic factors have been reported, of which urinary protein and renal function are the most critical parameters. Fractional excretion of total protein (FETP) indicates protein leakage that accounts for creatinine kinetics and serum protein levels. In this study, we investigated the association between FETP and renal prognosis in pMN. Methods We retrospectively identified 150 patients with pMN. FETP was calculated as follows: (serum creatinine × urine protein)/(serum protein × urine creatinine) %. We divided the patients into three groups according to FETP values and compared the clinicopathological findings. The primary outcome was an estimated glomerular filtration rate (eGFR) decrease of ≥30% from the baseline level. Results FETP was associated with urinary protein and renal function, Ehrenreich and Churg stage, and global glomerulosclerosis. The primary outcome was observed in 38 patients (25.3%), and the frequency of the primary outcome was higher in the high FETP group (P = .001). FETP is higher than protein-creatinine ratio (PCR) in the area under the curve. In the multivariate analysis adjusted for age, eGFR, PCR and treatment, FETP was significantly associated with primary outcome (adjusted hazard ratio, 8.19; P = .019). Conclusions FETP is a valuable indicator that can reflect the pathophysiology and is more useful than PCR as a predictor of renal prognosis in patients with Japanese pMN.
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Affiliation(s)
- Hideaki Kuno
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Go Kanzaki
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Takaya Sasaki
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Yusuke Okabayashi
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Kotaro Haruhara
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Shinya Yokote
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Kentaro Koike
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Hiroyuki Ueda
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Nobuo Tsuboi
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, The Jikei University School of Medicine, Tokyo, Japan
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Saulnier PJ, Looker HC, Layton A, Lemley KV, Nelson RG, Bjornstad P. Loss of Glomerular Permselectivity in Type 2 Diabetes Associates With Progression to Kidney Failure. Diabetes 2023; 72:1682-1691. [PMID: 37586079 PMCID: PMC10588283 DOI: 10.2337/db23-0310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 08/09/2023] [Indexed: 08/18/2023]
Abstract
We examined whether defects in glomerular size selectivity in type 2 diabetes are associated with progressive kidney disease. Glomerular filtration rate (GFR) and fractional clearances of dextrans of graded sizes were measured in 185 American Indians. The permselectivity model that best fit the dextran sieving data represented the glomerular capillary as being perforated by small restrictive pores and a parallel population of larger nonrestrictive pores characterized by ω0, the fraction of total filtrate volume passing through this shunt. The hazard ratio (HR) for kidney failure was expressed per 1-SD increase of ω0 by Cox regression after adjusting for age, sex, mean arterial pressure, HbA1c, GFR, and the urine albumin-to-creatinine ratio (ACR). Baseline mean ± SD age was 43 ± 10 years, HbA1c 8.9 ± 2.5%, GFR 147 ± 46 mL/min, and median (interquartile range) ACR 41 (11-230) mg/g. During a median follow-up of 17.7 years, 67 participants developed kidney failure. After adjustment, each 1-SD increment in ω0 was associated with a higher risk of kidney failure (HR 1.55 [95% CI 1.17, 2.05]). Enhanced transglomerular passage of test macromolecules was associated with progression to kidney failure, independent of albuminuria and GFR, suggesting that mechanisms associated with impaired glomerular permselectivity are important determinants of progressive kidney disease. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Pierre J. Saulnier
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ
- University of Poitiers, INSERM CIC1402, Poitiers, France
| | - Helen C. Looker
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ
| | - Anita Layton
- University of Waterloo, Waterloo, Ontario, Canada
| | - Kevin V. Lemley
- Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Robert G. Nelson
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ
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3
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Looker HC, Pyle L, Vigers T, Severn C, Saulnier PJ, Najafian B, Mauer M, Nelson RG, Bjornstad P. Structural Lesions on Kidney Biopsy in Youth-Onset and Adult-Onset Type 2 Diabetes. Diabetes Care 2022; 45:436-443. [PMID: 35006272 PMCID: PMC8914414 DOI: 10.2337/dc21-1688] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/17/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Type 2 diabetes (T2D) is a leading cause of end-stage kidney disease worldwide. Recent studies suggest a more aggressive clinical course of diabetic kidney disease in youth-onset compared with adult-onset T2D. We compared kidney structural lesions in youth- and adult-onset T2D to determine if youth onset was associated with greater early tissue injury. RESEARCH DESIGN AND METHODS Quantitative microscopy was performed on kidney tissue obtained from research kidney biopsies in 161 Pima Indians (117 women, 44 men) with T2D. Onset of T2D was established by serial oral glucose tolerance testing, and participants were stratified as youth onset (age <25 years) or adult onset (age ≥25 years). Associations between clinical and morphometric parameters and age at onset were tested using linear models. RESULTS At biopsy, the 52 participants with youth-onset T2D were younger than the 109 with adult-onset T2D (39.1 ± 9.9 vs. 51.4 ± 10.2 years; P < 0.0001), but their diabetes duration was similar (19.3 ± 8.1 vs. 17.0 ± 7.8 years; P = 0.09). Median urine albumin-to-creatinine ratio was higher in the youth-onset group (58 [25th-75th percentile 17-470] vs. 27 [13-73] mg/g; P = 0.02). Youth-onset participants had greater glomerular basement membrane (GBM) width (552 ± 128 vs. 490 ± 114 nm; P = 0.002) and mesangial fractional volume (0.31 ± 0.10 vs. 0.27 ± 0.08; P = 0.001) than adult-onset participants. Glomerular sclerosis percentage, glomerular volume, mesangial fractional volume, and GBM width were also inversely associated with age at diabetes onset as a continuous variable. CONCLUSIONS Younger age at T2D onset strongly associates with more severe kidney structural lesions. Studies are underway to elucidate the pathways underlying these associations.
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Affiliation(s)
- Helen C Looker
- National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ
| | | | | | | | - Pierre J Saulnier
- INSERM Centre d'Investigation Clinique 1402, University of Poitiers, Poitiers, France
| | | | | | - Robert G Nelson
- National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ
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4
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Saulnier PJ, Looker HC, Mauer M, Najafian B, Gand E, Ragot S, Nelson RG, Bjornstad P. Intraglomerular Dysfunction Predicts Kidney Failure in Type 2 Diabetes. Diabetes 2021; 70:2344-2352. [PMID: 34257069 PMCID: PMC8576505 DOI: 10.2337/db21-0154] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022]
Abstract
No longitudinal data link intraglomerular hemodynamic dysfunction with end-stage kidney disease (ESKD) in people with type 2 diabetes (T2D). Afferent (RA) and efferent (RE) arteriolar resistance and intraglomerular pressure (PGLO) are not directly measurable in humans but are estimable from glomerular filtration rate (GFR), renal plasma flow (RPF), blood pressure, hematocrit, and plasma oncotic pressure. We examined the association of the RA-to-RE ratio and PGLO with ESKD incidence in 237 Pima Indian individuals with T2D who underwent serial measures of GFR (iothalamate) and RPF (p-aminohippurate). Their association with kidney structural lesions was also examined in a subset of 111 participants. Of the 237 participants (mean age 42 years, diabetes duration 11 years, and GFR 153 mL/min and median urine albumin-to-creatinine ratio 36 mg/g), 69 progressed to ESKD during a median follow-up of 17.5 years. In latent class analysis, distinct trajectories characterized by increasing RA-to-RE ratio (HR 4.60, 95% CI 2.55-8.31) or elevated PGLO followed by a rapid decline (HR 2.96, 95% CI 1.45-6.02) strongly predicted incident ESKD. PGLO (R 2 = 21%, P < 0.0001) and RA-to-RE ratio (R 2 = 15%, P < 0.0001) also correlated with mesangial fractional volume, a structural predictor of DKD progression. In conclusion, intraglomerular hemodynamic parameters associated strongly with incident ESKD and correlated with structural lesions of DKD.
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Affiliation(s)
- Pierre J Saulnier
- NIDDK, Phoenix, AZ
- INSERM CIC1402, University of Poitiers, Poitiers, France
| | | | | | | | - Elise Gand
- INSERM CIC1402, University of Poitiers, Poitiers, France
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Satake E, Saulnier PJ, Kobayashi H, Gupta MK, Looker HC, Wilson JM, Md Dom ZI, Ihara K, O’Neil K, Krolewski B, Pipino C, Pavkov ME, Nair V, Bitzer M, Niewczas MA, Kretzler M, Mauer M, Doria A, Najafian B, Kulkarni RN, Duffin KL, Pezzolesi MG, Kahn CR, Nelson RG, Krolewski AS. Comprehensive Search for Novel Circulating miRNAs and Axon Guidance Pathway Proteins Associated with Risk of ESKD in Diabetes. J Am Soc Nephrol 2021; 32:2331-2351. [PMID: 34140396 PMCID: PMC8729832 DOI: 10.1681/asn.2021010105] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/23/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Mechanisms underlying the pro gression of diabetic kidney disease to ESKD are not fully understood. METHODS We performed global microRNA (miRNA) analysis on plasma from two cohorts consisting of 375 individuals with type 1 and type 2 diabetes with late diabetic kidney disease, and targeted proteomics analysis on plasma from four cohorts consisting of 746 individuals with late and early diabetic kidney disease. We examined structural lesions in kidney biopsy specimens from the 105 individuals with early diabetic kidney disease. Human umbilical vein endothelial cells were used to assess the effects of miRNA mimics or inhibitors on regulation of candidate proteins. RESULTS In the late diabetic kidney disease cohorts, we identified 17 circulating miRNAs, represented by four exemplars (miR-1287-5p, miR-197-5p, miR-339-5p, and miR-328-3p), that were strongly associated with 10-year risk of ESKD. These miRNAs targeted proteins in the axon guidance pathway. Circulating levels of six of these proteins-most notably, EFNA4 and EPHA2-were strongly associated with 10-year risk of ESKD in all cohorts. Furthermore, circulating levels of these proteins correlated with severity of structural lesions in kidney biopsy specimens. In contrast, expression levels of genes encoding these proteins had no apparent effects on the lesions. In in vitro experiments, mimics of miR-1287-5p and miR-197-5p and inhibitors of miR-339-5p and miR-328-3p upregulated concentrations of EPHA2 in either cell lysate, supernatant, or both. CONCLUSIONS This study reveals novel mechanisms involved in progression to ESKD and points to the importance of systemic factors in the development of diabetic kidney disease. Some circulating miRNAs and axon guidance pathway proteins represent potential targets for new therapies to prevent and treat this condition.
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Affiliation(s)
- Eiichiro Satake
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Pierre-Jean Saulnier
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona,Poitiers University Hospital, University of Poitiers, Institut National de la Santé et de la Recherche Médicale (INSERM), Clinical Investigation Center CIC1402, Poitiers, France
| | - Hiroki Kobayashi
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Manoj K. Gupta
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Helen C. Looker
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona
| | - Jonathan M. Wilson
- Diabetes and Complication Department, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Zaipul I. Md Dom
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Katsuhito Ihara
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Kristina O’Neil
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Bozena Krolewski
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Caterina Pipino
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts,Department of Medical, Oral and Biotechnological Sciences, Center for Advanced Studies and Technology (CAST), University G. d’Annunzio, Chieti, Italy
| | - Meda E. Pavkov
- Division of Diabetes Translation, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Viji Nair
- Nephrology/Internal Medicine and Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
| | - Markus Bitzer
- Nephrology/Internal Medicine and Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
| | - Monika A. Niewczas
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Matthias Kretzler
- Nephrology/Internal Medicine and Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
| | - Michael Mauer
- Department of Pediatrics and Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Alessandro Doria
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Behzad Najafian
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Rohit N. Kulkarni
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Kevin L. Duffin
- Diabetes and Complication Department, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Marcus G. Pezzolesi
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts,Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah
| | - C. Ronald Kahn
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Robert G. Nelson
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona
| | - Andrzej S. Krolewski
- Research Division, Joslin Diabetes Center, Boston, Massachusetts,Department of Medicine, Harvard Medical School, Boston, Massachusetts
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Saulnier PJ, Darshi M, Wheelock KM, Looker HC, Fufaa GD, Knowler WC, Weil EJ, Tanamas SK, Lemley KV, Saito R, Natarajan L, Nelson RG, Sharma K. Urine metabolites are associated with glomerular lesions in type 2 diabetes. Metabolomics 2018; 14:84. [PMID: 30830355 PMCID: PMC6461445 DOI: 10.1007/s11306-018-1380-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/02/2018] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Little is known about the association of urine metabolites with structural lesions in persons with diabetes. OBJECTIVES We examined the relationship between 12 urine metabolites and kidney structure in American Indians with type 2 diabetes. METHODS Data were from a 6-year clinical trial that assessed renoprotective efficacy of losartan, and included a kidney biopsy at the end of the treatment period. Metabolites were measured in urine samples collected within a median of 6.5 months before the research biopsy. Associations of the creatinine-adjusted urine metabolites with kidney structural variables were examined by Pearson's correlations and multivariable linear regression after adjustment for age, sex, diabetes duration, hemoglobin A1c, mean arterial pressure, glomerular filtration rate (iothalamate), and losartan treatment. RESULTS Participants (n = 62, mean age 45 ± 10 years) had mean ± standard deviation glomerular filtration rate of 137 ± 50 ml/min and median (interquartile range) urine albumin:creatinine ratio of 34 (14-85) mg/g near the time of the biopsy. Urine aconitic and glycolic acids correlated positively with glomerular filtration surface density (partial r = 0.29, P = 0.030 and r = 0.50, P < 0.001) and total filtration surface per glomerulus (partial r = 0.32, P = 0.019 and r = 0.43, P = 0.001). 2-ethyl 3-OH propionate correlated positively with the percentage of fenestrated endothelium (partial r = 0.32, P = 0.019). Citric acid correlated negatively with mesangial fractional volume (partial r=-0.36, P = 0.007), and homovanillic acid correlated negatively with podocyte foot process width (partial r=-0.31, P = 0.022). CONCLUSIONS Alterations of urine metabolites may associate with early glomerular lesions in diabetic kidney disease.
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Affiliation(s)
- Pierre-Jean Saulnier
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
- Clinical Investigation Center CIC1402, CHU Poitiers, University of Poitiers, INSERM, Poitiers, France
| | | | - Kevin M Wheelock
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | - Helen C Looker
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | - Gudeta D Fufaa
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | - William C Knowler
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | - E Jennifer Weil
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | - Stephanie K Tanamas
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA
| | | | - Rintaro Saito
- University of California San Diego, San Diego, CA, USA
| | | | - Robert G Nelson
- Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, AZ, USA.
- National Institutes of Health, 1550 East Indian School Road, Phoenix, AZ, 85014-4972, USA.
| | - Kumar Sharma
- University of California San Diego, San Diego, CA, USA
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Saulnier PJ, Wheelock KM, Howell S, Weil EJ, Tanamas SK, Knowler WC, Lemley KV, Mauer M, Yee B, Nelson RG, Beisswenger PJ. Advanced Glycation End Products Predict Loss of Renal Function and Correlate With Lesions of Diabetic Kidney Disease in American Indians With Type 2 Diabetes. Diabetes 2016; 65:3744-3753. [PMID: 27609106 PMCID: PMC5127241 DOI: 10.2337/db16-0310] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 09/05/2016] [Indexed: 12/20/2022]
Abstract
We examined associations of advanced glycation end products (AGEs) with renal function loss (RFL) and its structural determinants in American Indians with type 2 diabetes. Data were from a 6-year clinical trial that assessed renoprotective efficacy of losartan. Participants remained under observation after the trial concluded. Glomerular filtration rate (GFR) was measured annually. Kidney biopsies were performed at the end of the trial. Five AGEs were measured in serum collected at enrollment and at kidney biopsy. RFL was defined as ≥40% decline of measured GFR from baseline. Of 168 participants (mean baseline age 41 years, HbA1c 9.2%, GFR 164 mL/min, and albumin-to-creatinine ratio 31 mg/g), 104 reached the RFL end point during median follow-up of 8.0 years. After multivariable adjustment, each doubling of carboxyethyl lysine (hazard ratio [HR] 1.60 [95% CI 1.08-2.37]) or methylglyoxal hydroimidazolone (HR 1.30 [95% CI 1.02-1.65]) concentration was associated with RFL. Carboxyethyl lysine, carboxymethyl lysine, and methylglyoxal hydroimidazolone correlated positively with cortical interstitial fractional volume (partial r = 0.23, P = 0.03; partial r = 0.25, P = 0.02; and partial r = 0.31, P = 0.003, respectively). Glyoxyl hydroimidazolone and methylglyoxal hydroimidazolone correlated negatively with total filtration surface per glomerulus (partial r = -0.26, P = 0.01; and partial r = -0.21, P = 0.046, respectively). AGEs improve prediction of RFL and its major structural correlates.
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Affiliation(s)
- Pierre-Jean Saulnier
- Phoenix Epidemiology and Clinical Research Branch, Phoenix, AZ
- CHU Poitiers, University of Poitiers, Clinical Investigation Center, INSERM CIC1402, Poitiers, France
| | | | | | - E Jennifer Weil
- Phoenix Epidemiology and Clinical Research Branch, Phoenix, AZ
| | | | | | - Kevin V Lemley
- Department of Pediatrics, University of Southern California Keck School of Medicine, Children's Hospital Los Angeles, Los Angeles, CA
| | - Michael Mauer
- Department of Pediatrics and Medicine, University of Minnesota, Minneapolis, MN
| | - Berne Yee
- Southwest Kidney Institute, Phoenix, AZ
| | - Robert G Nelson
- Phoenix Epidemiology and Clinical Research Branch, Phoenix, AZ
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Fufaa GD, Weil EJ, Lemley KV, Knowler WC, Brosius FC, Yee B, Mauer M, Nelson RG. Structural Predictors of Loss of Renal Function in American Indians with Type 2 Diabetes. Clin J Am Soc Nephrol 2016; 11:254-61. [PMID: 26792530 DOI: 10.2215/cjn.05760515] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/14/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Diabetes is the leading cause of kidney failure in the United States, but early structural determinants of renal function loss in type 2 diabetes are poorly defined. We examined the association between morphometrically determined renal structural variables and loss of renal function in 111 American Indians with type 2 diabetes who volunteered for a research kidney biopsy at the end of a 6-year clinical trial designed to test the renoprotective efficacy of losartan versus placebo. Participants were subsequently followed in an observational study, in which annual measurements of GFR (iothalamate) initiated during the clinical trial were continued. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Renal function loss was defined as ≥40% loss of GFR from the research examination performed at the time of kidney biopsy. Associations with renal function loss were evaluated by Cox proportional hazards regression. Hazard ratios (HRs) were reported per 1-SD increment for each morphometric variable. RESULTS Of 111 participants (82% women; baseline mean [±SD] age, 46 years old [±10]; diabetes duration, 16 years [±6]; hemoglobin A1c =9.4% [±2.2]; GFR=147 ml/min [±56]; median albumin-to-creatinine ratio, 41 mg/g [interquartile range, 13-158]), 51 (46%) developed renal function loss during a median follow-up of 6.6 years (interquartile range, 3.1-9.0). Fourteen had baseline GFR <90 ml/min, and three had baseline GFR <60 ml/min. Higher mesangial fractional volume (HR, 2.27; 95% confidence interval [95% CI], 1.58 to 3.26), percentage of global glomerular sclerosis (HR, 1.63; 95% CI, 1.21 to 2.21), nonpodocyte cell number per glomerulus (HR, 1.50; 95% CI, 1.10 to 2.05), glomerular basement membrane width (HR, 1.48; 95% CI, 1.05 to 2.08), mean glomerular volume (HR, 1.42; 95% CI, 1.02 to 1.96), and podocyte foot process width (HR, 1.28; 95% CI, 1.03 to 1.60); lower glomerular filtration surface density (HR, 0.62; 95% CI, 0.41 to 0.94); and fewer endothelial fenestrations (HR, 0.68; 95% CI, 0.48 to 0.95) were each associated with GFR decline after adjustment for baseline age, sex, duration of diabetes, hemoglobin A1c, GFR, and treatment assignment during the clinical trial. CONCLUSIONS Quantitative measures of glomerular structure predict loss of renal function in type 2 diabetes.
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Affiliation(s)
- Gudeta D Fufaa
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
| | - E Jennifer Weil
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
| | - Kevin V Lemley
- Department of Pediatrics, University of Southern California Keck School of Medicine, Children's Hospital Los Angeles, Los Angeles, California
| | - William C Knowler
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
| | - Frank C Brosius
- Division of Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Berne Yee
- Southwest Kidney Institute, Phoenix, Arizona; and
| | - Michael Mauer
- Department of Pediatrics and Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Robert G Nelson
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona;
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Woo SH, Sigdel TK, Dinh VT, Vu MT, Sarwal MM, Lafayette RA. Mapping novel immunogenic epitopes in IgA nephropathy. Clin J Am Soc Nephrol 2014; 10:372-81. [PMID: 25542908 DOI: 10.2215/cjn.02390314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES IgA plays a key role in IgA nephropathy (IgAN) by forming immune complexes and depositing in the glomeruli, leading to an inflammatory response. However, the antigenic targets and functional characterization of IgA have been incompletely defined in this disease. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study was performed in sera from patients who were studied as part of a prospective, observational study of IgAN. These patients (n=22) all had biopsy-proven IgAN within 3 years of study initiation, complete clinical data, annual urinary inulin clearance for GFRs, and at least 5 years of follow-up. Progression was defined as loss of >5 ml/min per 1.73 m(2) per year of inulin clearance measured over at least 5 years. A protein microarray was used for detection of IgAN-specific IgA autoantibodies in blood across approximately 9000 human antigens to specifically identify the most immunogenic protein targets that drive IgA antibodies in IgAN (n=22), healthy controls (n=10), and non-IgAN glomerular diseases (n=17). Results were validated by ELISA assays in sera and by immunohistochemistry in IgAN kidney biopsies. IgA-specific antibodies were correlated with clinical and histologic variables to assess their effect on disease progression and prognosis. RESULTS Fifty-four proteins mounted highly significant IgA antibody responses in patients with IgAN with a false discovery rate (q value) of ≤10%; 325 antibodies (P≤0.05) were increased overall. Antitissue transglutaminase IgA was significantly elevated in IgAN (P<0.001, q value of 0%). IgA antibodies to DDX4 (r=-0.55, P=0.01) and ZADH2 (r=-0.48, P=0.02) were significantly correlated with the decline of renal function. Specific IgA autoantibodies are elevated in IgAN compared with normal participants and those with other glomerular diseases. CONCLUSIONS In this preliminary study, IgA autoantibodies target novel proteins, highly expressed in the kidney glomerulus and tubules. These IgA autoantibodies may play important roles in the pathogenesis of IgAN.
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Affiliation(s)
- Sang Hoon Woo
- Division of Hospital Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Tara K Sigdel
- Department of Surgery, University of California, San Francisco, California
| | - Van T Dinh
- Department of Surgery, University of California, San Francisco, California
| | - Minh-Thien Vu
- Department of Surgery, University of California, San Francisco, California
| | - Minnie M Sarwal
- Department of Surgery, University of California, San Francisco, California;
| | - Richard A Lafayette
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford University, Stanford, California
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10
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Kriz W, Lemley KV. A potential role for mechanical forces in the detachment of podocytes and the progression of CKD. J Am Soc Nephrol 2014; 26:258-69. [PMID: 25060060 DOI: 10.1681/asn.2014030278] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Loss of podocytes underlies progression of CKD. Detachment of podocytes from the glomerular basement membrane (GBM) rather than apoptosis or necrosis seems to be the major mechanism of podocyte loss. Such detachment of viable podocytes may be caused by increased mechanical distending and shear forces and/or impaired adhesion to the GBM. This review considers the mechanical challenges that may lead to podocyte loss by detachment from the GBM under physiologic and pathophysiologic conditions, including glomerular hypertension, hyperfiltration, hypertrophy, and outflow of filtrate from subpodocyte spaces. Furthermore, we detail the cellular mechanisms by which podocytes respond to these challenges, discuss the protective effects of angiotensin blockade, and note the questions that must be addressed to better understand the relationship between podocyte detachment and progression of CKD.
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Affiliation(s)
- Wilhelm Kriz
- Institutes of Transfusion Medicine and Immunology and Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany; and
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California; and Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, California
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11
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Pollak MR, Quaggin SE, Hoenig MP, Dworkin LD. The glomerulus: the sphere of influence. Clin J Am Soc Nephrol 2014; 9:1461-9. [PMID: 24875196 DOI: 10.2215/cjn.09400913] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The glomerulus, the filtering unit of the kidney, is a unique bundle of capillaries lined by delicate fenestrated endothelia, a complex mesh of proteins that serve as the glomerular basement membrane and specialized visceral epithelial cells that form the slit diaphragms between interdigitating foot processes. Taken together, this arrangement allows continuous filtration of the plasma volume. The dynamic physical forces that determine the single nephron glomerular filtration are considered. In addition, new insights into the cellular and molecular components of the glomerular tuft and their contribution to glomerular disorders are explored.
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Affiliation(s)
- Martin R Pollak
- Beth Israel Deaconess Medical Center, Boston, Massachusetts;
| | - Susan E Quaggin
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois; and
| | | | - Lance D Dworkin
- Brown Medical School, Brown University, Providence, Rhode Island
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12
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The Effects of Helicobacter pylori Eradication on Proteinuria in Patients with Primary Glomerulonephritis. Int J Nephrol 2014; 2014:180690. [PMID: 24707402 PMCID: PMC3953655 DOI: 10.1155/2014/180690] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 01/06/2014] [Accepted: 01/13/2014] [Indexed: 11/17/2022] Open
Abstract
Background. Membranous nephropathy (MN) is a common cause of nephrotic syndrome. In most cases it is idiopathic, while it may also be secondary to many diseases. In this study, prevalence of H. pylori infection and the effects of H. pylori eradication on proteinuria levels were investigated. Methods. Thirty five patients with MN (19 male), 12 patients with IgA nephropathy (4 male) and 12 patients with focal segmental glomerulosclerosis (FSGS) (8 male) were studied. The presence of H. pylori antigen was investigated in renal tissues obtained by biopsy, and the effects of H. pylori eradication on proteinuria levels were investigated. Results. Immunohistochemistry with H. pylori antigen revealed no positive staining in the glomeruli of all patients. 19 patients (54%) with MN, 10 (83%) with IgA nephropathy and 4 (33%) with FSGS were positive for H. pylori stool antigen test (P = 0.045). Patients with H. pylori infection were administered eradication therapy (lansoprazole, 30 mg twice daily, plus amoxicillin, 0.75 g twice daily, plus clarithromycin, 250 mg twice daily, for 14 days). Before the eradication therapy the mean proteinuria of patients with MN, IgA nephropathy and FSGS were 2.42 ± 3.24 g/day, 2.12 ± 1.63 g/day and 1.80 ± 1.32 g/day, respectively. Three months after eradication, baseline proteinuria levels of patients with MN significantly decreased to 1.26 ± 1.73 g/day (P = 0.031). In all three groups there were no significant differences with regard to serum creatinine, albumin and C-reactive protein levels before and after eradication therapy. Conclusions. The eradication of H. pylori infection may be effective to reduce proteinuria in patients with MN, while spontaneous remission of MN could not be excluded in this patient cohort. This trial is registered with NCT00983034.
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Abstract
Membranous nephropathy is characterized by immune complex deposits on the outer side of the glomerular basement membrane. Activation of complement and of oxidation lead to basement membrane lesions. The most frequent form is idiopathic. At 5 and 10 years, renal survival is around 90 and 65% respectively. A prognostic model based on proteinuria, level and duration, progression of renal failure in a few months can refine prognosis. The urinary excretion of C5b-9, β2 and α1 microglobuline and IgG are strong predictors of outcome. Symptomatic treatment is based on anticoagulation in case of nephrotic syndrome, angiotensin conversion enzyme inhibitors, angiotensin II receptor blockers and statins. Immunosuppressive therapy should be discussed for patients having a high risk of progression. Corticoids alone has no indication. Treatment should include a simultaneous association or more often alternating corticoids and alkylant agent for a minimum of 6 months. Adrenocorticoid stimulating hormone and steroids plus mycophenolate mofetil may be equally effective. Steroids plus alkylant decrease the risk of end stage renal failure. Cyclosporine and tacrolimus decrease proteinuria but are associated with a high risk of recurrence at time of withdrawal and are nephrotoxic. Rituximab evaluated on open studies needs further evaluations to define its use.
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Affiliation(s)
- Lucile Mercadal
- Service de néphrologie, groupe hospitalier Pitié-Salpêtrière, 83, boulevard de l'Hôpital, 75013 Paris, France.
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Sigdel TK, Woo SH, Dai H, Khatri P, Li L, Myers B, Sarwal MM, Lafayette RA. Profiling of autoantibodies in IgA nephropathy, an integrative antibiomics approach. Clin J Am Soc Nephrol 2012; 6:2775-84. [PMID: 22157707 DOI: 10.2215/cjn.04600511] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES IgG commonly co-exists with IgA in the glomerular mesangium of patients with IgA nephropathy (IgAN) with unclear clinical relevance. Autoantibody (autoAb) biomarkers to detect and track progression of IgAN are an unmet clinical need. The objective of the study was to identify IgA-specific autoAbs specific to IgAN. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS High-density protein microarrays were evaluated IgG autoAbs in the serum of IgAN patients (n = 22) and controls (n = 10). Clinical parameters, including annual GFR and urine protein measurements, were collected on all patients over 5 years. Bioinformatic data analysis was performed to select targets for further validation by immunohistochemistry (IHC). RESULTS One hundred seventeen (1.4%) specific antibodies were increased in IgAN. Among the most significant were the autoAb to the Ig family of proteins. IgAN-specific autoAbs (approximately 50%) were mounted against proteins predominantly expressed in glomeruli and tubules, and selected candidates were verified by IHC. Receiver operating characteristic analysis of our study demonstrated that IgG autoAb levels (matriline 2, ubiquitin-conjugating enzyme E2W, DEAD box protein, and protein kinase D1) might be used in combination with 24-hour proteinuria to improve prediction of the progression of IgAN (area under the curve = 0.86, P = 0.02). CONCLUSIONS IgAN is associated with elevated IgG autoAbs to multiple proteins in the kidney. This first analysis of the repertoire of autoAbs in IgAN identifies novel, immunogenic protein targets that are highly expressed in the kidney glomerulus and tubules that may bear relevance in the pathogenesis and progression of IgAN.
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Affiliation(s)
- Tara K Sigdel
- Departments of Pediatrics-Nephrology, Stanford University School of Medicine, Stanford, CA 94304, USA
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15
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Tsuboi N, Kawamura T, Miyazaki Y, Utsunomiya Y, Hosoya T. Low glomerular density is a risk factor for progression in idiopathic membranous nephropathy. Nephrol Dial Transplant 2011; 26:3555-60. [PMID: 21771759 DOI: 10.1093/ndt/gfr399] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The adverse histological features predicting a progressive loss of renal function in idiopathic membranous nephropathy (IMN), before the establishment of impaired renal function with advanced glomerulosclerosis and/or interstitial fibrosis, are still poorly understood. The present study examined the relationship between the glomerular density (GD; non-sclerotic glomerular number/renal cortical area of biopsy) and the renal prognosis in IMN patients, especially in those without any apparent renal dysfunction at the time of diagnosis. METHODS The predictive value of the factors at biopsy, including the GD, on the renal outcome was retrospectively analyzed in the 65 IMN patients with an estimated glomerular filtration rate (eGFR) of ≥ 60 mL/min/1.73 m(2) (mean, 80 mL/min/1.73 m(2)) at biopsy. RESULTS The individual values for GD ranged from 1.6 to 6.5/mm(2) with 4-fold variation. A lower GD was associated with progression based on a ≥ 50% reduction in eGFR or reaching to end-stage renal disease. An association between a lower GD and progression was observed, especially in patients with persistent proteinuria of ≥ 1 g/day at follow-up. In contrast, any patients who achieved proteinuria of <1 g/day at follow-up did not show progression regardless of their GD levels. In addition, among the various clinicopathological factors observed, the GD was the only factor at biopsy that independently predicted the slope of the renal function during the observation periods. CONCLUSION These results suggest that low GD is a plausible risk factor for progression in IMN patients, especially in those that do not achieve a remission of proteinuria during the follow-up.
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Affiliation(s)
- Nobuo Tsuboi
- Division of Kidney and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
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16
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Edwards A. Modeling transport in the kidney: investigating function and dysfunction. Am J Physiol Renal Physiol 2009; 298:F475-84. [PMID: 19889951 DOI: 10.1152/ajprenal.00501.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Mathematical models of water and solute transport in the kidney have significantly expanded our understanding of renal function in both health and disease. This review describes recent theoretical developments and emphasizes the relevance of model findings to major unresolved questions and controversies. These include the fundamental processes by which urine is concentrated in the inner medulla, the ultrastructural basis of proteinuria, irregular flow oscillation patterns in spontaneously hypertensive rats, and the mechanisms underlying the hypotensive effects of thiazides. Macroscopic models of water, NaCl, and urea transport in populations of nephrons have served to test, confirm, or refute a number of hypotheses related to the urine concentrating mechanism. Other macroscopic models focus on the mechanisms, role, and irregularities of renal hemodynamic control and on the regulation of renal oxygenation. At the mesoscale, models of glomerular filtration have yielded significant insight into the ultrastructural basis underlying a number of disorders. At the cellular scale, models of epithelial solute transport and pericyte Ca2+ signaling are being used to elucidate transport pathways and the effects of hormones and drugs. Areas where further theoretical progress is conditional on experimental advances are also identified.
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Affiliation(s)
- Aurélie Edwards
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155, USA.
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17
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Fischer K, McDannold NJ, Zhang Y, Kardos M, Szabo A, Szabo A, Reusz GS, Jolesz FA. Renal ultrafiltration changes induced by focused US. Radiology 2009; 253:697-705. [PMID: 19703861 DOI: 10.1148/radiol.2532082100] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PURPOSE To determine if focused ultrasonography (US) combined with a diagnostic microbubble-based US contrast agent can be used to modulate glomerular ultrafiltration and size selectivity. MATERIALS AND METHODS The experiments were approved by the animal care committee. The left kidney of 17 healthy rabbits was sonicated by using a 260-kHz focused US transducer in the presence of a microbubble-based US contrast agent. The right kidney served as the control. Three acoustic power levels were applied: 0.4 W (six rabbits), 0.9 W (six rabbits), and 1.7 W (five rabbits). Three rabbits were not treated with focused US and served as control animals. The authors evaluated changes in glomerular size selectivity by measuring the clearance rates of 3000- and 70,000-Da fluorescence-neutral dextrans. The creatinine clearance was calculated for estimation of the glomerular filtration rate. The urinary protein-creatinine ratio was monitored during the experiments. The authors assessed tubular function by evaluating the fractional sodium excretion, tubular reabsorption of phosphate, and gamma-glutamyltransferase-creatinine ratio. Whole-kidney histologic analysis was performed. For each measurement, the values obtained before and after sonication were compared by using the paired t test. RESULTS Significant (P < .05) increases in the relative (ratio of treated kidney value/nontreated kidney value) clearance of small- and large-molecule agents and the urine flow rates that resulted from the focused US treatments were observed. Overall, 1.23-, 1.23-, 1.61-, and 1.47-fold enhancement of creatinine clearance, 3000-Da dextran clearance, 70 000-Da dextran clearance, and urine flow rate, respectively, were observed. Focal tubular hemorrhage and transient functional tubular alterations were observed at only the highest (1.7-W) acoustic power level tested. CONCLUSION Glomerular ultrafiltration and size selectivity can be temporarily modified with simultaneous application of US and microbubbles. This method could offer new opportunities for treatment of renal disease.
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Affiliation(s)
- Krisztina Fischer
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Focused Ultrasound Laboratory, 221 Longwood Ave, Room 515, Boston, MA 02215, USA.
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Fukase S, Kazama JJ, Mori H, Iguchi S, Takeda T, Ueno M, Nishi S, Narita I, Gejyo F. Para-capillary electron-dense deposits reduce glomerular filtration in patients with primary glomerular diseases. Clin Exp Nephrol 2006; 10:33-9. [PMID: 16544176 DOI: 10.1007/s10157-005-0401-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 11/29/2005] [Indexed: 11/26/2022]
Abstract
BACKGROUND Electron-dense deposits are often found around glomerular capillary lumens in patients with glomerulonephritis, forming a portion of the blood-urine barrier (BUB). METHODS Four hundred and four patients with primary glomerular diseases or donors for living-related kidney transplantation who underwent both percutaneous renal biopsy and renal clearance tests were included in the study. Sodium thiosulfate and paraamino hippurate double-clearance studies were performed with catheterized urinary collection. The filtration fraction (FF) was determined as follows: FF = sodium thiosulfate clearance/paraamino hippurate clearance (CPAH: ). Histomorphometric analyses were performed in 53 patients with overt para-capillary electron-dense deposits (PCEDD) by electron microscopic observations. RESULTS Patients with membranous nephropathy and membranoproliferative glomerulonephritis showed significantly lower levels of FF than the donors for living-rebated kidney transplantation (normal controls). FF levels were significantly lower in patients with PCEDD than in those without (P < 0.001), while the levels of mean blood pressure and CPAH: were comparable in the two groups. The PCEDD/BUB ratio demonstrated a significant negative correlation with FF (P < 0.0001; r(2) = 0.331). Patients with a ratio of 0.5 or more showed significantly lower FF levels than those with a ratio of 0.25 or less. CONCLUSIONS PCEDD significantly affected FF levels in patients with primary glomerular diseases. FF may not be an accurate indicator of intraglomerular blood pressure in patients with overt PCEDD.
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Affiliation(s)
- Sachiko Fukase
- Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, 1-754 Asahimachi-Dori, Niigata 951-8510, Japan
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Ronco P, Debiec H. Molecular pathomechanisms of membranous nephropathy: from Heymann nephritis to alloimmunization. J Am Soc Nephrol 2005; 16:1205-13. [PMID: 15800120 DOI: 10.1681/asn.2004121080] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Membranous nephropathy (MN), the most common cause of idiopathic nephrotic syndrome in white adults, is characterized by an accumulation of immune deposits on the outer aspect of the glomerular basement membrane. In Heymann nephritis, the rat experimental model for MN, megalin--the target antigen of the nephritogenic antibodies--is expressed on the surface of podocytes, where immune complexes are formed, leading to complement activation and nephrotic-range proteinuria. However, megalin cannot be held responsible for human MN because it has not been found in human podocytes or detected in subepithelial immune deposits in patients with MN. Several potential antigens have been identified in so-called secondary forms of MN, but there is no real proof that these antigens are pathogenic. In a subgroup of infants with antenatal MN, neutral endopeptidase (NEP) has been identified as the first protein target on human podocytes of nephritogenic antibodies. The infants' mothers became immunized during pregnancy against NEP expressed on syncytiotrophoblastic cells because they were NEP deficient as a result of truncating mutations in the MME gene. Severity of neonatal renal disease was determined by the mothers' IgG response that led to the formation of the membrane attack complex of complement in the subepithelial deposits. Alloimmunization against NEP is a novel pathomechanism of MN that might also account for some cases of MN after renal or bone marrow transplantation. Other types of alloimmunization should be investigated in MN but also in other renal and nonrenal diseases, particularly those that affect the pediatric age.
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Affiliation(s)
- Pierre Ronco
- INSERM Unit 489, Tenon Hôpital (Assistance Publique, Hôpitaux de Paris), 4 rue de la Chine, 75020 Paris, France.
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Debiec H, Nauta J, Coulet F, van der Burg M, Guigonis V, Schurmans T, de Heer E, Soubrier F, Janssen F, Ronco P. Role of truncating mutations in MME gene in fetomaternal alloimmunisation and antenatal glomerulopathies. Lancet 2004; 364:1252-9. [PMID: 15464186 DOI: 10.1016/s0140-6736(04)17142-0] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Membranous glomerulonephritis is an immune-mediated disease. In a recent case of antenatal membranous glomerulonephritis, we identified neutral endopeptidase (NEP) as the podocyte target antigen of circulating antibodies produced by the mother who failed to express NEP on granulocytes. We aimed to investigate whether the disease could affect other families, to search for mutations in the metallomembrane endopeptidase (MME) gene for NEP, and to analyse the outcome of the antenatal renal insult. METHODS From three families with a case of neonatal membranous glomerulopathy, we detected mutations by direct sequencing of genomic PCR products. Single nucleotide polymorphism (SNP) analysis was undertaken with five SNPs located in the MME gene. IgG subclasses with anti-NEP activity were determined by western blotting. FINDINGS In five mothers, we identified two compound heterozygous or homozygous mutations in the MME gene. The first, a 1342C-->T nonsense mutation, was detected in one family. The second, 446delC, was detected in all three families; all chromosomes bearing this mutation had the same alleles for the five SNPs. Severity of neonatal renal disease was determined by the mothers' IgG response to fetal NEP antigens expressed on glomerular podocytes. The oldest affected individual, now aged 20 years, has developed severe chronic renal failure. INTERPRETATION Truncating mutations in the MME gene are the cause of alloimmunisation during pregnancy. Idiopathic renal failure in early adulthood might be caused by immune-mediated fetal nephron loss. We show that disease caused by fetomaternal alloimmunisation secondary to a genetic defect is not restricted to blood cells. RELEVANCE TO CLINICAL PRACTICE During pregnancy, the absence of the NEP protein induces an alloimmunisation process against NEP presented by fetal cells, including syncytiotrophoblasts. The fetal podocyte insult and ensuing nephron loss could lead to chronic renal failure in early adulthood. Alloimmunisation against NEP should be considered as a leading cause of membranous glomerulopathy early in life. Concentrations of circulating anti-NEP antibodies should be carefully monitored during subsequent pregnancies, and specific therapeutic approaches developed. This new disease might also account for idiopathic chronic renal failure detected during adolescence, in individuals who can be identified by searching for anti-NEP antibodies in their mother and by MME gene mutation analysis. NEP deficiency should also be considered in patients developing de-novo membranous glomerulopathy after renal transplantation.
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Affiliation(s)
- Hanna Debiec
- INSERM Unit 489, Tenon Hospital (AP-HP) and University of Paris 6, Paris, France.
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Hoang K, Tan JC, Derby G, Blouch KL, Masek M, Ma I, Lemley KV, Myers BD. Determinants of glomerular hypofiltration in aging humans. Kidney Int 2003; 64:1417-24. [PMID: 12969161 DOI: 10.1046/j.1523-1755.2003.00207.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The purpose of the present study was to confirm the extent to which glomerular filtration rate (GFR) is depressed in healthy, aging subjects and to elucidate the mechanism of such hypofiltration. METHODS Healthy volunteers aged 18 to 88 years (N = 159) underwent a determination of GFR, renal plasma flow (RPF), afferent oncotic pressure, and arterial pressure. Glomeruli in renal biopsies of healthy kidney transplant donors aged 23 to 69 years (N = 33) were subjected to a morphometric analysis, so as to determine glomerular hydraulic permeability and filtration surface area. The aforementioned GFR determinants were then subjected to mathematical modeling to compute the glomerular ultrafiltration coefficient (Kf) for two kidneys and individual glomeruli. RESULTS GFR was significantly depressed (P < 0.0001) by 22% in aging (>or=55 years old) compared to youthful subjects (<or=40 years old). Corresponding reductions of the following GFR determinants in the aging vs. youthful subsets were RPF by 28% (P < 0.0001), two-kidney Kf by 21% to 53% (P < 0.005), glomerular hydraulic permeability by 14% (P = 0.03), and the single-nephron Kf (SNKf) by 30% (P = 0.09). There were no significant differences between aging and youthful subsets for afferent oncotic pressure and filtration surface area per glomerulus. CONCLUSION We conclude that a reduction in overall, two-kidney Kf contributes to GFR depression in aging subjects. We infer that this is due in part to structural changes that lower SNKf, and in part to the reduction in the actual number of functioning glomeruli that has been demonstrated by others at autopsy.
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Affiliation(s)
- Khoi Hoang
- Department of Medicine, Stanford University School of Medicine, Stanford, California, USA
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Hladunewich MA, Lemley KV, Blouch KL, Myers BD. Determinants of GFR depression in early membranous nephropathy. Am J Physiol Renal Physiol 2003; 284:F1014-22. [PMID: 12527555 DOI: 10.1152/ajprenal.00273.2002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated the glomerular filtration rate (GFR) in 34 subjects with membranous nephropathy (MN) of new onset. We used physiological techniques to measure GFR, renal plasma flow, and oncotic pressure and computed a value for the two-kidney ultrafiltration coefficient (K(f)). A morphometric analysis of glomeruli in the diagnostic biopsy permitted computation of the single-nephron ultrafiltration coefficient (SNK(f)). MN subjects were divided into two groups: moderate or severe, according to whether GFR was depressed by less or more than 50%. SNK(f) was subnormal but similar in moderate and severe MN. In contrast, two-kidney K(f) was significantly more depressed in severe than in moderate MN. We estimated the total number of functioning glomeruli (N(g)) by dividing two-kidney K(f) by SNK(f). Whereas mean N(g) was similar in controls and moderate MN (1.5 and 1.4-1.7 x 10(6), respectively), it was significantly lower in severe MN (0.5 x 10(6)). This degree of glomerulopenia was not reflected in the rate of global sclerosis. We conclude that a combination of depressed SNK(f) (due to foot process broadening) and profound glomerulopenia accounts for GFR depression of >50% early in the course of MN. The cause of the glomerulopenia remains to be elucidated.
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Affiliation(s)
- M A Hladunewich
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
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Lemley KV. A basis for accelerated progression of diabetic nephropathy in Pima Indians. KIDNEY INTERNATIONAL. SUPPLEMENT 2003:S38-42. [PMID: 12864873 DOI: 10.1046/j.1523-1755.63.s83.9.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Pima Indians of Arizona not only have a much higher incidence of nephropathy due to type 2 diabetes than Caucasians, but they also lose their renal function at an accelerated rate after they develop diabetic nephropathy. This rapid loss of renal function occurs despite a younger age of onset of nephropathy and lower blood pressures and lipid levels, all of which would seem to predict a slower rate of progression of nephropathy. These findings suggest that other factors contribute to the rapid progression of renal disease in this population. In particular, glomerulomegaly in this population may contribute to the high rate of glomerular filtration rate (GFR) loss during the terminal, clinically manifest phase of nephropathy, because of the greater incremental loss of single-nephron GFR (SNGFR) with each nephron lost to sclerosis. In nine Pima Indians with type 2 diabetic nephropathy who underwent renal biopsy followed by serial iothalamate clearances for up to ten years, we examined the relationship between glomerular tuft volume at initial biopsy and the rate of GFR loss during the terminal phase. By multivariate analysis, significant independent effects of both glomerular volume (P=0.006) and podocyte density (P=0.043) were evident in these individuals. The effect of glomerular volume may result from a greater loss of intrinsic filtration capacity with each glomerulus lost, while the effect of podocyte density may reflect the destabilizing influence of "podocyte insufficiency" on the glomerular tuft. Similar factors may play a role in the rapid loss of GFR associated with progressive glomerular diseases in other indigenous populations in whom glomerulomegaly and glomerulopenia coexist.
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Affiliation(s)
- Kevin V Lemley
- Division of Pediatric Nephrology, Stanford University School of Medicine, Stanford, California 94305, USA.
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Lemley KV, Lafayette RA, Safai M, Derby G, Blouch K, Squarer A, Myers BD. Podocytopenia and disease severity in IgA nephropathy. Kidney Int 2002; 61:1475-85. [PMID: 11918755 DOI: 10.1046/j.1523-1755.2002.00269.x] [Citation(s) in RCA: 231] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND IgA nephropathy is a common form of progressive glomerular disease, associated with proliferation of mesangial cells and mesangial deposition of IgA. The present study was designed to investigate functional and morphological covariates of disease severity in patients with IgA nephropathy. METHODS Glomerular hemodynamics, permselectivity and ultrastructure were studied in 17 adult patients with IgA nephropathy using inulin, para-aminohippuric acid (PAH) and 3H-Ficoll clearances and morphometric methods. A mathematical model of macromolecule permeation through a heteroporous membrane was used to characterize glomerular permselectivity. Controls consisted of 14 healthy living kidney donors and 12 healthy volunteers. RESULTS The patients were heterogeneous in their disease severity, but as a group had a decreased glomerular filtration rate (GFR) and increased urinary protein excretion compared to controls [63 +/- 29 SD vs. 104 +/- 23 mL/min/1.73 m2, P < 0.001, and (median) 1.34 vs. 0.11 g/day, P < 0.0001, respectively). A multivariate analysis of structural and functional relationships revealed GFR depression to be most strongly correlated with the prevalence of global glomerular sclerosis (t = -4.073, P = 0.002). Those patients with the most severe glomerular dysfunction had a reduced number of glomerular visceral epithelial cells (podocytes) per glomerulus. The degree of podocytopenia was related to the extent of glomerular sclerosis and of impairment of permselectivity and GFR, with worsening injury below an apparent threshold podocyte number of about 250 cells per glomerulus. There were no corresponding correlations between these indices of injury and the number of mesangial and endothelial cells. CONCLUSIONS Our findings show that podocyte loss is a concomitant of increasing disease severity in IgA nephropathy. This suggests that podocyte loss may either cause or contribute to the progressive proteinuria, glomerular sclerosis and filtration failure seen in this disorder.
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Affiliation(s)
- Kevin V Lemley
- Division of Pediatric Nephrology, Stanford University School of Medicine,Stanford, California 94305-5208, USA.
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Abstract
Recent progress in relating the functional properties of the glomerular capillary wall to its unique structure is reviewed. The fenestrated endothelium, glomerular basement membrane (GBM), and epithelial filtration slits form a series arrangement in which the flow diverges as it enters the GBM from the fenestrae and converges again at the filtration slits. A hydrodynamic model that combines morphometric findings with water flow data in isolated GBM has predicted overall hydraulic permeabilities that are consistent with measurements in vivo. The resistance of the GBM to water flow, which accounts for roughly half that of the capillary wall, is strongly dependent on the extent to which the GBM surfaces are blocked by cells. The spatial frequency of filtration slits is predicted to be a very important determinant of the overall hydraulic permeability, in keeping with observations in several glomerular diseases in humans. Whereas the hydraulic resistances of the cell layers and GBM are additive, the overall sieving coefficient for a macromolecule (its concentration in Bowman's space divided by that in plasma) is the product of the sieving coefficients for the individual layers. Models for macromolecule filtration reveal that the individual sieving coefficients are influenced by one another and by the filtrate velocity, requiring great care in extrapolating in vitro observations to the living animal. The size selectivity of the glomerular capillary has been shown to be determined largely by the cellular layers, rather than the GBM. Controversial findings concerning glomerular charge selectivity are reviewed, and it is concluded that there is good evidence for a role of charge in restricting the transmural movement of albumin. Also discussed is an effect of albumin that has received little attention, namely, its tendency to increase the sieving coefficients of test macromolecules via steric interactions. Among the unresolved issues are the specific contributions of the endothelial glycocalyx and epithelial slit diaphragm to the overall hydraulic resistance and macromolecule selectivity and the nanostructural basis for the observed permeability properties of the GBM.
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Affiliation(s)
- W M Deen
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.
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Kon V, Ichikawa I. Prospects for gene transfer into renal cells. Kidney Int 2000; 57:2169-70. [PMID: 10792640 DOI: 10.1046/j.1523-1755.2000.00072.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Focal segmental glomerulosclerosis is a pathological hallmark of many forms of progressive renal disease. The 'classic' lesion, based on the adhesion of the capillary tuft to Bowman's capsule, results from the loss of podocytes from the capillary basement membrane. The recently described 'collapsing' variant, in contrast, has an apparent excess of extracapillary cells, which may represent dedifferentiated, 'dysregulated' podocytes.
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Affiliation(s)
- W Kriz
- Institut für Anatomie und Zellbiologie, INF 307, Universität Heidelberg, Germany.
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