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Meliambro K, He JC, Campbell KN. Podocyte-targeted therapies - progress and future directions. Nat Rev Nephrol 2024; 20:643-658. [PMID: 38724717 DOI: 10.1038/s41581-024-00843-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2024] [Indexed: 09/14/2024]
Abstract
Podocytes are the key target cells for injury across the spectrum of primary and secondary proteinuric kidney disorders, which account for up to 90% of cases of kidney failure worldwide. Seminal experimental and clinical studies have established a causative link between podocyte depletion and the magnitude of proteinuria in progressive glomerular disease. However, no substantial advances have been made in glomerular disease therapies, and the standard of care for podocytopathies relies on repurposed immunosuppressive drugs. The past two decades have seen a remarkable expansion in understanding of the mechanistic basis of podocyte injury, with prospects increasing for precision-based treatment approaches. Dozens of disease-causing genes with roles in the pathogenesis of clinical podocytopathies have been identified, as well as a number of putative glomerular permeability factors. These achievements, together with the identification of novel targets of podocyte injury, the development of potential approaches to harness the endogenous podocyte regenerative potential of progenitor cell populations, ongoing clinical trials of podocyte-specific pharmacological agents and the development of podocyte-directed drug delivery systems, contribute to an optimistic outlook for the future of glomerular disease therapy.
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Affiliation(s)
- Kristin Meliambro
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John C He
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kirk N Campbell
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Yadav M, Jadon T, Singh G, Devi KG, Chandan M, Khandelwal P, Meena J, Geetha TS, Faruq M, Hari P, Sinha A, Bagga A. Spectrum of Alport syndrome in an Indian cohort. Pediatr Nephrol 2024:10.1007/s00467-024-06507-1. [PMID: 39278986 DOI: 10.1007/s00467-024-06507-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Revised: 08/06/2024] [Accepted: 08/13/2024] [Indexed: 09/18/2024]
Abstract
BACKGROUND Next-generation sequencing has enabled non-invasive diagnosis of type IV collagen disease in clinical settings other than the typical presentation of Alport syndrome (AS). METHODS We reviewed the clinical and histological records of children diagnosed with Alport syndrome based on next-generation sequencing. Variants on clinical exome sequencing were categorized using ACMG 2015 criteria. RESULTS During 2015-2023, we found 43 patients (34 boys) with 39 variants in COL4A5 (n = 27), COL4A4 (n = 7), and COL4A3 (n = 5). Thirty, 8, and 5 patients had X-linked, autosomal recessive, and autosomal dominant disease, respectively. The median (IQR) age and eGFR at diagnosis were 10 (7-13) years and 100.1 (59-140) ml/min/1.73 m2, respectively. Fifteen patients were initially diagnosed with steroid-resistant nephrotic syndrome. Alport syndrome was suspected in these patients due to persistent microscopic hematuria, eGFR < 90 ml/min/1.73 m2, characteristic histology, and/or non-response to immunosuppression. Of 26 patients who underwent kidney biopsy, light microscopy revealed focal segmental glomerulosclerosis, minimal change disease, and mesangial proliferative glomerulonephritis in 9, 9, and 8 patients, respectively. Electron microscopy (n = 18) showed characteristic glomerular basement membrane changes and/or foot process effacement in 12 and 16 cases, respectively. Twenty-one patients (48.8%) had high-frequency sensorineural hearing loss, while two had lenticonus. Twelve patients progressed to chronic kidney disease stages 4-5. Median survival (IQR) with eGFR > 30 ml/min/1.73 m2 was 15.6 (13-18) years. CONCLUSIONS The phenotype of Alport syndrome varies from asymptomatic urinary abnormalities to hematuria, proteinuria and/or low eGFR, and steroid-resistant nephrotic syndrome. Adverse outcomes are common, especially in boys with X-linked disease.
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Affiliation(s)
- Menka Yadav
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Trishla Jadon
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Geetika Singh
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Kshetrimayum Ghanapriya Devi
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Monica Chandan
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Priyanka Khandelwal
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Jitendra Meena
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | | | - Mohammed Faruq
- Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology, Delhi, India
| | - Pankaj Hari
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Aditi Sinha
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
| | - Arvind Bagga
- Division of Nephrology, ICMR Center for Advanced Research in Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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Nozu K, Resontoc LPR, Hooman N, Vasudevan A, Ding J, Kang HG. Investigation of the current situation regarding diagnosis and treatment of Alport syndrome in Asian countries: results of survey of the Asian Paediatric Nephrology association (AsPNA) tubular and inherited working group. Clin Exp Nephrol 2023; 27:776-780. [PMID: 37289334 PMCID: PMC10432360 DOI: 10.1007/s10157-023-02358-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023]
Abstract
BACKGROUND Alport syndrome is one of the most common inherited kidney diseases worldwide. A genetic test or kidney biopsy is necessary for a definite diagnosis of this disease, and an accurate diagnosis system for this disease is highly desired in each country. However, the current situation in Asian countries is not clear. Therefore, the tubular and inherited disease working group of the Asian Pediatric Nephrology Association (AsPNA) aimed to assess the current situation of diagnosis and treatment for Alport syndrome in Asia. METHODS The group conducted an online survey among the members of AsPNA in 2021-2022. Collected data included the number of patients for each inheritance mode, availability of gene tests or kidney biopsy, and treatment strategies for Alport syndrome. RESULTS A total of 165 pediatric nephrologists from 22 countries in Asia participated. Gene test was available in 129 institutes (78%), but the cost was still expensive in most countries. Kidney biopsy was available in 87 institutes (53%); however, only 70 can access electron microscopy, and 42 can conduct type IV collagen α5 chain staining. Regarding treatment, 140 centers use renin-angiotensin system (RAS) inhibitors (85%) for Alport syndrome patients. CONCLUSIONS This study result might suggest that the system is underdeveloped enough to diagnose all Alport syndrome patients in most Asian countries. However, once diagnosed with Alport syndrome, most of them were treated with RAS inhibitors. These survey results can be used to address knowledge, diagnostic system, and treatment strategy gaps and improve the Alport patients' outcomes in Asian countries.
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Affiliation(s)
- Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-Cho, Chuo, Kobe, Hyogo, 650-0017, Japan.
| | - Lourdes Paula Real Resontoc
- Division of Pediatric Nephrology, College of Medicine, University of the Philippines-Philippine General Hospital, Manila, Philippines
| | - Nakysa Hooman
- Ali Asghar Clinical Research Development Center, Department of Pediatrics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Anil Vasudevan
- Department of Pediatric Nephrology, St John's Medical College Hospital, Bengaluru, India
| | - Jie Ding
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, South Korea
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Kuwazuru J, Suico MA, Omachi K, Kojima H, Kamura M, Kaseda S, Kawahara T, Hitora Y, Kato H, Tsukamoto S, Wada M, Asano T, Kotani S, Nakajima M, Misumi S, Sannomiya Y, Horizono J, Koyama Y, Owaki A, Shuto T, Kai H. CyclosporinA Derivative as Therapeutic Candidate for Alport Syndrome by Inducing Mutant Type IV Collagen Secretion. KIDNEY360 2023; 4:909-917. [PMID: 37143203 PMCID: PMC10371266 DOI: 10.34067/kid.0000000000000134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 04/04/2023] [Indexed: 05/06/2023]
Abstract
Key Points Screening of natural product extracts to find candidate compounds that increase mutant type IV collagen α 3,4,5 (α 345(IV)) trimer secretion in Alport syndrome (AS). Cyclosporin A (CsA) and alisporivir (ALV) increase mutant α 345(IV) trimer secretion in AS. PPIF/cyclophilin D mediates the effect of CsA and ALV on mutant trimer secretion. Background Type IV collagen α 3,4,5 (α 345(IV)) is an obligate trimer that is secreted to form a collagen network, which is the structural foundation of basement membrane. Mutation in one of the genes (COL4A3 , A4 , A5 ) encoding these proteins underlies the progressive genetic nephropathy Alport syndrome (AS) due to deficiency in trimerization and/or secretion of the α 345(IV) trimer. Thus, improving mutant α 345(IV) trimerization and secretion could be a good therapeutic approach for AS. Methods Using the nanoluciferase-based platform that we previously developed to detect α 345(IV) formation and secretion in HEK293T cells, we screened libraries of natural product extracts and compounds to find a candidate compound capable of increasing mutant α 345(IV) secretion. Results The screening of >13,000 extracts and >600 compounds revealed that cyclosporin A (CsA) increased the secretion of mutant α 345(IV)-G1244D. To elucidate the mechanism of the effect of CsA, we evaluated CsA derivatives with different ability to bind to calcineurin (Cn) and cyclophilin (Cyp). Alisporivir (ALV), which binds to Cyp but not to Cn, increased the trimer secretion of mutant α 345(IV). Knockdown studies on Cyps showed that PPIF/cyclophilin D was involved in the trimer secretion-enhancing activity of CsA and ALV. We confirmed that other α 345(IV) mutants are also responsive to CsA and ALV. Conclusions CsA was previously reported to improve proteinuria in patients with AS, but owing to its nephrotoxic effect, CsA is not recommended for treatment in patients with AS. Our data raise the possibility that ALV could be a safer option than CsA. This study provides a novel therapeutic candidate for AS with an innovative mechanism of action and reveals an aspect of the intracellular regulatory mechanism of α 345(IV) that was previously unexplored.
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Affiliation(s)
- Jun Kuwazuru
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Mary Ann Suico
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kohei Omachi
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Haruka Kojima
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Misato Kamura
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Shota Kaseda
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Teppei Kawahara
- Department of Instrumental Analysis, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Useful and Unique Natural Products for Drug Discovery and Development (UpRod), Program for Building Regional Innovation Ecosystems, Kumamoto University, Kumamoto, Japan
| | - Yuki Hitora
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Department of Natural Medicines, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Hikaru Kato
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Department of Natural Medicines, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Sachiko Tsukamoto
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Department of Natural Medicines, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Mikiyo Wada
- Department of Instrumental Analysis, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Useful and Unique Natural Products for Drug Discovery and Development (UpRod), Program for Building Regional Innovation Ecosystems, Kumamoto University, Kumamoto, Japan
| | - Toshifumi Asano
- Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Shunsuke Kotani
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Department of Instrumental Analysis, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Makoto Nakajima
- Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Shogo Misumi
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Yuya Sannomiya
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Jun Horizono
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Yuimi Koyama
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Aimi Owaki
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Tsuyoshi Shuto
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Hirofumi Kai
- Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Global Center for Natural Resources Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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Oda Y, Sawa N, Nozu K, Ubara Y. Refractory focal segmental glomerulosclerosis caused by Alport syndrome detected by genetic testing after three decades. BMJ Case Rep 2022; 15:e247393. [PMID: 35288428 PMCID: PMC8921854 DOI: 10.1136/bcr-2021-247393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2022] [Indexed: 01/13/2023] Open
Abstract
A woman in her 50s with a three-decade history of biopsy-proven focal segmental glomerulosclerosis and a family history of end-stage kidney disease presented with worsening proteinuria and declining kidney function after three decades of immunosuppressive therapy. While a repeat kidney biopsy did not reveal findings diagnostic of Alport syndrome, genetic testing demonstrated a heterozygous mutation in COL4A5, which confirmed the diagnosis of X-linked Alport syndrome. The heterozygous in-frame deletion mutation may explain her intact hearing and relatively mild symptoms. Genetic testing enables diagnosis of Alport syndrome of various phenotypes, some of which cannot be diagnosed conventionally with clinical course and kidney biopsy. Genetic disorders including collagen IV nephropathy should be considered as a differential diagnosis in patients with focal segmental glomerulosclerosis, especially when a patient has early-onset proteinuria, a family history of kidney disease, syndromic features or proteinuria refractory to glucocorticoid treatment.
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Affiliation(s)
- Yasuhiro Oda
- Division of Nephrology and Endocrinology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Naoki Sawa
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yoshifumi Ubara
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
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Ning L, Suleiman HY, Miner JH. Synaptopodin deficiency exacerbates kidney disease in a mouse model of Alport syndrome. Am J Physiol Renal Physiol 2021; 321:F12-F25. [PMID: 34029143 DOI: 10.1152/ajprenal.00035.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Synaptopodin (Synpo) is an actin-associated protein in podocyte foot processes. By generating mice that completely lack Synpo, we previously showed that Synpo is dispensable for normal kidney function. However, lack of Synpo worsened adriamycin-induced nephropathy, indicating a protective role for Synpo in injured podocytes. Here, we investigated whether lack of Synpo directly impacts a genetic disease, Alport syndrome (AS), because Synpo is reduced in podocytes of affected humans and mice; whether this is merely an association or pathogenic is unknown. We used collagen type IV-α5 (Col4a5) mutant mice, which model X-linked AS, showing glomerular basement membrane (GBM) abnormalities, eventual foot process effacement, and progression to end-stage kidney disease. We intercrossed mice carrying mutations in Synpo and Col4a5 to produce double-mutant mice. Urine and tissue were taken at select time points to evaluate albuminuria, histopathology, and glomerular capillary wall composition and ultrastructure. Lack of Synpo in Col4a5-/Y, Col4a5-/-, or Col4a5+/- Alport mice led to the acceleration of disease progression, including more severe proteinuria and glomerulosclerosis. Absence of Synpo attenuated the shift of myosin IIA from the podocyte cell body and major processes to actin cables near the GBM in the areas of effacement. We speculate that this is mechanistically associated with enhanced loss of podocytes due to easier detachment from the GBM. We conclude that Synpo deletion exacerbates the disease phenotype in Alport mice, revealing the podocyte actin cytoskeleton as a target for therapy in patients with AS.NEW & NOTEWORTHY Alport syndrome (AS) is a hereditary disease of the glomerular basement with hematuria and proteinuria. Podocytes eventually exhibit foot process effacement, indicating actin cytoskeletal changes. To investigate how cytoskeletal changes impact podocytes, we generated Alport mice lacking synaptopodin, an actin-binding protein in foot processes. Analysis showed a more rapid disease progression, demonstrating that synaptopodin is protective. This suggests that the actin cytoskeleton is a target for therapy in AS and perhaps other glomerular diseases.
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Affiliation(s)
- Liang Ning
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Hani Y Suleiman
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jeffrey H Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
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Ozdemir G, Gulhan B, Atayar E, Saygılı S, Soylemezoglu O, Ozcakar ZB, Eroglu FK, Candan C, Demir BK, Soylu A, Yüksel S, Alpay H, Agbas A, Duzova A, Hayran M, Ozaltin F, Topaloglu R. COL4A3 mutation is an independent risk factor for poor prognosis in children with Alport syndrome. Pediatr Nephrol 2020; 35:1941-1952. [PMID: 32394188 DOI: 10.1007/s00467-020-04574-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/03/2020] [Accepted: 04/07/2020] [Indexed: 01/14/2023]
Abstract
BACKGROUND Alport syndrome (AS) is an inherited glomerular disease caused by mutations in COL4A3, COL4A4, or COL4A5. Associations between clinical manifestations and genotype are not yet well defined. Our study aimed to define clinical and genetic characteristics, establish genotype-phenotype correlations, and determine prognosis of AS in children. METHODS A total of 87 children with AS from 10 pediatric nephrology centers, whom had genetic analyses performed at the Hacettepe University Nephrogenetics Laboratory between February 2017 and February 2019, were included. Data regarding demographics, family history, clinical and laboratory characteristics, histopathological and genetic test results, treatments, and yearly follow-up results were retrospectively analyzed. RESULTS Of 87 patients, 16% presented with nephrotic syndrome. In patients with nephrotic syndrome, kidney biopsy findings showed focal segmental glomerulosclerosis (FSGS) in 79%, and COL4A3 mutations were the leading genetic abnormality (50%). Twenty-four percent of all patients progressed to chronic kidney disease (CKD). The rate of progression to CKD and the decline in the glomerular filtration rate of the patients with COL4A3 mutation were higher than other mutation groups (p < 0.001 and p = 0.04, respectively). In kidney survival analysis, nephrotic syndrome presentation, histopathology of FSGS, COL4A3 mutations, and autosomal recessive inheritance were found as independent risk factors for earlier progression to CKD. Cyclosporin A treatment did not improve kidney survival. CONCLUSIONS We emphasize that genetic testing is important for patients suspected as having AS. Furthermore, COL4A mutations should be considered in patients with FSGS and steroid-resistant nephrotic syndrome. This approach will shed light on the prognosis of patients and help with definitive diagnosis, preventing unnecessary and potentially harmful medications. Graphical abstract.
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Affiliation(s)
- Gulsah Ozdemir
- Division of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, 06230, Ankara, Turkey
| | - Bora Gulhan
- Division of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, 06230, Ankara, Turkey
| | - Emine Atayar
- Division of Pediatric Nephrology, Nephrogenetics Laboratory, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Seha Saygılı
- Division of Pediatric Nephrology, Faculty of Medicine, Istanbul University-Cerrahpaşa, Istanbul, Turkey
| | - Oguz Soylemezoglu
- Division of Pediatric Nephrology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Zeynep Birsin Ozcakar
- Division of Pediatric Nephrology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Fehime Kara Eroglu
- Division of Pediatric Nephrology, Dr. Sami Ulus Maternity and Children's Health Hospital, Ankara, Turkey
| | - Cengiz Candan
- Division of Pediatric Nephrology, Göztepe Training and Research Hospital, Istanbul Medeniyet University, Istanbul, Turkey
| | - Belde Kasap Demir
- Division of Pediatric Nephrology, Tepecik Training and Research Hospital, Izmir, Turkey
| | - Alper Soylu
- Division of Pediatric Nephrology, Faculty of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Selçuk Yüksel
- Division of Pediatric Nephrology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Harika Alpay
- Division of Pediatric Nephrology, Faculty of Medicine, Marmara University, Istanbul, Turkey
| | - Ayse Agbas
- Division of Pediatric Nephrology, Haseki Training and Research Hospital, Istanbul, Turkey
| | - Ali Duzova
- Division of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, 06230, Ankara, Turkey
| | - Mutlu Hayran
- Department of Preventive Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Fatih Ozaltin
- Division of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, 06230, Ankara, Turkey.,Division of Pediatric Nephrology, Nephrogenetics Laboratory, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Rezan Topaloglu
- Division of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, 06230, Ankara, Turkey.
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Abstract
Alport syndrome (AS) is a progressive hereditary renal disease that is characterized by sensorineural hearing loss and ocular abnormalities. It is divided into three modes of inheritance, namely, X-linked Alport syndrome (XLAS), autosomal recessive AS (ARAS), and autosomal dominant AS (ADAS). XLAS is caused by pathogenic variants in COL4A5, while ADAS and ARAS are caused by those in COL4A3/COL4A4. Diagnosis is conventionally made pathologically, but recent advances in comprehensive genetic analysis have enabled genetic testing to be performed for the diagnosis of AS as first-line diagnosis. Because of these advances, substantial information about the genetics of AS has been obtained and the genetic background of this disease has been revealed, including genotype-phenotype correlations and mechanisms of onset in some male XLAS cases that lead to milder phenotypes of late-onset end-stage renal disease (ESRD). There is currently no radical therapy for AS and treatment is only performed to delay progression to ESRD using nephron-protective drugs. Angiotensin-converting enzyme inhibitors can remarkably delay the development of ESRD. Recently, some new drugs for this disease have entered clinical trials or been developed in laboratories. In this article, we review the diagnostic strategy, genotype-phenotype correlation, mechanisms of onset of milder phenotypes, and treatment of AS, among others.
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9
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Nozu K, Nakanishi K, Abe Y, Udagawa T, Okada S, Okamoto T, Kaito H, Kanemoto K, Kobayashi A, Tanaka E, Tanaka K, Hama T, Fujimaru R, Miwa S, Yamamura T, Yamamura N, Horinouchi T, Minamikawa S, Nagata M, Iijima K. A review of clinical characteristics and genetic backgrounds in Alport syndrome. Clin Exp Nephrol 2018; 23:158-168. [PMID: 30128941 PMCID: PMC6510800 DOI: 10.1007/s10157-018-1629-4] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 08/06/2018] [Indexed: 01/15/2023]
Abstract
Alport syndrome (AS) is a progressive hereditary renal disease that is characterized by sensorineural hearing loss and ocular abnormalities. It is divided into three modes of inheritance, namely, X-linked Alport syndrome (XLAS), autosomal recessive AS (ARAS), and autosomal dominant AS (ADAS). XLAS is caused by pathogenic variants in COL4A5, while ADAS and ARAS are caused by those in COL4A3/COL4A4. Diagnosis is conventionally made pathologically, but recent advances in comprehensive genetic analysis have enabled genetic testing to be performed for the diagnosis of AS as first-line diagnosis. Because of these advances, substantial information about the genetics of AS has been obtained and the genetic background of this disease has been revealed, including genotype–phenotype correlations and mechanisms of onset in some male XLAS cases that lead to milder phenotypes of late-onset end-stage renal disease (ESRD). There is currently no radical therapy for AS and treatment is only performed to delay progression to ESRD using nephron-protective drugs. Angiotensin-converting enzyme inhibitors can remarkably delay the development of ESRD. Recently, some new drugs for this disease have entered clinical trials or been developed in laboratories. In this article, we review the diagnostic strategy, genotype–phenotype correlation, mechanisms of onset of milder phenotypes, and treatment of AS, among others.
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Affiliation(s)
- Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
| | - Koichi Nakanishi
- Department of Child Health and Welfare (Pediatrics), Graduate School of Medicine, University of the Ryukyus, Nishihara, Japan
| | - Yoshifusa Abe
- Children Medical Center, Showa University Northern Yokohama Hospital, Yokohama, Kanagawa, Japan
| | - Tomohiro Udagawa
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shinichi Okada
- Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Tottori, Japan
| | - Takayuki Okamoto
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hiroshi Kaito
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Katsuyoshi Kanemoto
- Department of Pediatrics, National Hospital Organization Chiba-East Hospital, Chiba, Japan
| | - Anna Kobayashi
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Kofu, Japan
| | - Eriko Tanaka
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kazuki Tanaka
- Department of Nephrology, Aichi Children's Health and Medical Center, Obu, Japan
| | - Taketsugu Hama
- Department of Pediatrics, Wakayama Medical University, Wakayama, Japan
| | - Rika Fujimaru
- Department of Pediatrics, Osaka City General Hospital, Izumi, Japan
| | - Saori Miwa
- Department of Pediatrics, The Jikei University School of Medicine, Tokyo, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Natsusmi Yamamura
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, Izumi, Japan
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Shogo Minamikawa
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
| | - Michio Nagata
- Kidney and Vascular Pathology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan
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Zhang Y, Ding J. Renal, auricular, and ocular outcomes of Alport syndrome and their current management. Pediatr Nephrol 2018; 33:1309-1316. [PMID: 28864840 DOI: 10.1007/s00467-017-3784-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 08/01/2017] [Accepted: 08/10/2017] [Indexed: 01/27/2023]
Abstract
Alport syndrome is a hereditary glomerular basement membrane disease caused by mutations in the COL4A3/4/5 genes encoding the type IV collagen alpha 3-5 chains. Most cases of Alport syndrome are inherited as X-linked dominant, and some as autosomal recessive or autosomal dominant. The primary manifestations are hematuria, proteinuria, and progressive renal failure, whereas some patients present with sensorineural hearing loss and ocular abnormalities. Renin-angiotensin-aldosterone system blockade is proven to delay the onset of renal failure by reducing proteinuria. Renal transplantation is a curative treatment for patients who have progressed to end-stage renal disease. However, only supportive measures can be used to improve hearing loss and visual loss. Although both stem cell therapy and gene therapy aim to repair the basement membrane defects, technical difficulties require more research in Alport mice before clinical studies. Here, we review the renal, auricular, and ocular manifestations and outcomes of Alport syndrome and their current management.
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Affiliation(s)
- Yanqin Zhang
- Pediatric Department, Peking University First Hospital, Beijing, China
| | - Jie Ding
- Pediatric Department, Peking University First Hospital, Beijing, China.
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Cervera-Acedo C, Coloma A, Huarte-Loza E, Sierra-Carpio M, Domínguez-Garrido E. Phenotype variability in a large Spanish family with Alport syndrome associated with novel mutations in COL4A3 gene. BMC Nephrol 2017; 18:325. [PMID: 29089023 PMCID: PMC5664579 DOI: 10.1186/s12882-017-0735-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 09/25/2017] [Indexed: 11/30/2022] Open
Abstract
Background Alport syndrome is an inherited renal disorder characterized by glomerular basement membrane lesions with hematuria, proteinuria and frequent hearing defects and ocular abnormalities. The disease is associated with mutations in genes encoding α3, α4, or α5 chains of type IV collagen, namely COL4A3 and COL4A4 in chromosome 2 and COL4A5 in chromosome X. In contrast to the well-known X-linked and autosomal recessive phenotypes, there is very little information about the autosomal dominant. In view of the wide spectrum of phenotypes, an exact diagnosis is sometimes difficult to achieve. Methods We investigated a Spanish family with variable phenotype of autosomal dominant Alport syndrome using clinical, histological, and genetic analysis. Results Mutational analysis of COL4A3 and COL4A4 genes showed a novel heterozygous mutation (c. 998G > A; p.G333E) in exon 18 of the COL4A3 gene. Among relatives carrying the novel mutation, the clinical phenotype was variable. Two additional COL4A3 mutations were found, a Pro-Leu substitution in exon 48 (p.P1461L) and a Ser-Cys substitution in exon 49 (p.S1492C), non-pathogenics alone. Conclusion Carriers of p.G333E and p.P1461L or p.S1492C mutations in COL4A3 gene appear to be more severely affected than carriers of only p.G333E mutation, and the clinical findings has an earlier onset. In this way, we could speculate on a synergistic effect of compound heterozygosity that could explain the different phenotype observed in this family.
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Affiliation(s)
- C Cervera-Acedo
- Molecular Diagnostics Unit, Center for Biomedical Research (CIBIR), Fundación Rioja Salud, C/Piqueras 98, 26006, Logroño, La Rioja, Spain
| | - A Coloma
- Department of Nephrology, San Pedro Hospital, Logroño, La Rioja, Spain
| | - E Huarte-Loza
- Department of Nephrology, San Pedro Hospital, Logroño, La Rioja, Spain
| | - M Sierra-Carpio
- Department of Nephrology, San Pedro Hospital, Logroño, La Rioja, Spain
| | - E Domínguez-Garrido
- Molecular Diagnostics Unit, Center for Biomedical Research (CIBIR), Fundación Rioja Salud, C/Piqueras 98, 26006, Logroño, La Rioja, Spain.
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Uchida N, Kumagai N, Nozu K, Fu XJ, Iijima K, Kondo Y, Kure S. Early RAAS Blockade Exerts Renoprotective Effects in Autosomal Recessive Alport Syndrome. TOHOKU J EXP MED 2017; 240:251-257. [PMID: 27904025 DOI: 10.1620/tjem.240.251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Alport syndrome is a progressive renal disease caused by mutations in COL4A3, COL4A4, and COL4A5 genes that encode collagen type IV alpha 3, alpha 4, and alpha 5 chains, respectively. Because of abnormal collagen chain, glomerular basement membrane becomes fragile and most of the patients progress to end-stage renal disease in early adulthood. COL4A5 mutation causes X-linked form of Alport syndrome, and two mutations in either COL4A3 or COL4A4 causes an autosomal recessive Alport syndrome. Recently, renin-angiotensin-aldosterone system (RAAS) blockade has been shown to attenuate effectively disease progression in Alport syndrome. Here we present three Japanese siblings and their father all diagnosed with autosomal recessive Alport syndrome and with different clinical courses, suggesting the importance of the early initiation of RAAS blockade. The father was diagnosed with Alport syndrome. His consanguineous parents and his wife were healthy. All three siblings showed hematuria since infancy. Genetic analysis revealed that they shared the same gene mutations in COL4A3 in a compound heterozygous state: c.2330G>A (p.Gly777Ala) from the mother and c.4354A>T (p.Ser1452Cys) from the father. Although RAAS blockade was initiated for the older sister and brother when their renal function was already impaired, it did not attenuate disease progression. In the youngest brother, RAAS blockade was initiated during normal renal function stage. After the initiation, his renal function has been normal with the very mild proteinuria to date at the age of 17 years. We propose that in Alport syndrome, RAAS blockade should be initiated earlier than renal function is impaired.
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Affiliation(s)
- Nao Uchida
- Department of Pediatrics, Tohoku University School of Medicine
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Peng L, Wei SY, Li LT, He YX, Li B. Comparison of different therapies in high-risk patients with idiopathic membranous nephropathy. J Formos Med Assoc 2016; 115:11-8. [DOI: 10.1016/j.jfma.2015.07.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 07/19/2015] [Accepted: 07/27/2015] [Indexed: 10/23/2022] Open
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Angiopoietin-Like-4, a Potential Target of Tacrolimus, Predicts Earlier Podocyte Injury in Minimal Change Disease. PLoS One 2015; 10:e0137049. [PMID: 26352670 PMCID: PMC4564140 DOI: 10.1371/journal.pone.0137049] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/12/2015] [Indexed: 12/02/2022] Open
Abstract
Podocyte injury plays central roles in proteinuria and kidney dysfunction, therefore, identifying specific biomarker to evaluate earlier podocyte injury is highly desirable. Podocyte-secreted angiopoietin-like-4 (Angptl4) mediates proteinuria in different types of podocytopathy. In the present study, we established an experimental minimal change disease (MCD) rat model, induced by adriamycin (ADR) and resulted in definite podocyte injury, to identify the dynamic changes in Angptl4 expression. We also investigated the direct effects of tacrolimus on Angptl4 and podocyte repair. We determined that the glomerular Angptl4 expression was rapidly upregulated and reached a peak earlier than desmin, an injured podocyte marker, in the ADR rats. Furthermore, this upregulation occurred prior to heavy proteinuria and was accompanied by increased urinary Angptl4. We observed that the Angptl4 upregulation occurred only when podocyte was mainly damaged since we didn’t observe little Angptl4 upregulation in MsPGN patients. In addition, we observed the glomerular Angptl4 mainly located in injured podocytes rather than normal podocytes. Moreover, we found that tacrolimus treatment significantly promoted podocyte repair and reduced glomerular and urinary Angptl4 expression at an earlier stage with a significant serum Angptl4 upregulation. And similar results were confirmed in MCD patients. In conclusion, this study represents the first investigation to demonstrate that Angptl4 can predict podocyte injury at earlier stages in MCD and the identification of earlier podocyte injury biomarkers could facilitate the prompt diagnosis and treatment of patients with podocytopathy, as well as determination of the prognosis and treatment efficacy in these diseases.
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The calcineurin inhibitor tacrolimus reduces proteinuria in membranous nephropathy accompanied by a decrease in angiopoietin-like-4. PLoS One 2014; 9:e106164. [PMID: 25165975 PMCID: PMC4148427 DOI: 10.1371/journal.pone.0106164] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 07/30/2014] [Indexed: 11/19/2022] Open
Abstract
Tacrolimus is an anticalcineurinic agent with potent immunosuppressive activity that has recently been shown to have the added benefit of reducing proteinuria in membranous nephropathy (MN) patients. However, its potential mechanisms remain unknown. To reveal the mechanism, rat cohorts were administered tacrolimus or vehicle from days 7 to 28 after the induction of passive Heymann nephritis (PHN). PHN induction resulted in heavy proteinuria and increased expression of desmin, a marker of injured podocytes. We also showed that the glomerular expression of angiopoietin-like-4 (Angptl4) was markedly upregulated in PHN rats and human MN followed by an increase in urine Angptl4 excretion. In addition, increased Angptl4 expression may be related to podocyte injury and proteinuria. Furthermore, upregulated Angptl4 expression primarily colocalized with podocytes rather than endothelial or mesangial cells, indicating that podocytes may be the source of Angptl4, which then gradually migrated to the glomerular basement membrane over time. However, tacrolimus treatment markedly reduced glomerular and urinary Angptl4, accompanied by a reduction in the established proteinuria and the promotion of podocyte repair. Additionally, glomerular immune deposits and circulating IgG levels induced by PHN clearly decreased following tacrolimus treatment. In conclusion, this is the first demonstration that the calcineurin inhibitor tacrolimus can reduce Angptl4 in podocytes accompanied by a decrease in established proteinuria and promotion of podocyte repair in MN.
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Giani M, Mastrangelo A, Villa R, Turolo S, Marra G, Tirelli AS, Hopfer H, Edefonti A. Alport syndrome: the effects of spironolactone on proteinuria and urinary TGF-β1. Pediatr Nephrol 2013; 28:1837-42. [PMID: 23748277 DOI: 10.1007/s00467-013-2490-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/16/2013] [Accepted: 04/09/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Alport syndrome (AS) is a progressive hereditary glomerular disease. Recent data indicate that aldosterone promotes fibrosis mediated by the transforming growth factor-β1 (TGF-β1) pathway, which may worsen proteinuria. Spironolactone (SP) antagonizes aldosterone and this study aimed to evaluate the efficacy of SP in reducing proteinuria and urinary TGF-β1 excretion in proteinuric AS patients. METHODS The study involved ten children with AS, normal renal function, and persistent proteinuria (>6 months; uPr/uCr ratio >1). SP 25 mg once a day for 6 months was added to existing ACE inhibitor treatment with or without angiotensin-II receptor blockade. Urine and blood samples were examined monthly. Urinary TGF-β1 levels were measured twice before and three times during SP treatment. Plasma renin activity (PRA) and serum aldosterone levels were also measured. In eight patients, uProt/uCreat was also assessed after 9 months and 12 months of SP treatment. RESULTS After beginning SP therapy, all patients showed significant decrease in mean uProt/uCreat ratio (1.77 ± 0.8 to 0.86 ± 0.6; p < 0.001) and mean urinary TGF-β1 levels (104 ± 54 to 41 ± 20 pg/mgCreatinine; p < 0.01), beginning after 30 days of treatment and remaining stable throughout SP administration. PRA remain unchanged, and mean serum aldosterone increased from 105 ± 72 pg/ml to 303 ± 156 pg/ml (p < 0.001). The only side effect was gynecomastia in an obese boy. After 1 year of therapy, mean uProt/uCreat remains low (0.82 ± 0.48). CONCLUSIONS Addition of SP to ACE-I treatment with or without angiotensin II receptor blokers (ARB) significantly reduced proteinuria. This was mediated by decreased urinary TGF-β1 levels and not associated with major side effects.
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Affiliation(s)
- Marisa Giani
- Pediatric Nephrology and Dialysis Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via della Commenda 9, 20122, Milan, Italy
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An update on the pathomechanisms and future therapies of Alport syndrome. Pediatr Nephrol 2013; 28:1025-36. [PMID: 22903660 DOI: 10.1007/s00467-012-2272-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/12/2012] [Accepted: 07/13/2012] [Indexed: 01/08/2023]
Abstract
Alport Syndrome (AS) is an inherited progressive disease that is caused by mutations of the genes encoding the key collagen chains, α3, α4, and α5, which are necessary for the composition of collagen type IV to form a robust glomerular basement membrane (GBM), capable of withstanding the significant biomechanical strain to which the glomerulus is subjected. Progressive loss of the filtration barrier allows excessive proteinuria, which ultimately leads to end-stage kidney disease (ESKD). The evidence for a beneficial renoprotective effect of renin-angiotensin-aldosterone system (RAAS) blockade by angiotensin-converting enzyme (ACE) inhibition and/or angiotensin receptor blockers (ARBs) is well established in AS and recent evidence has shown that it can significantly delay the time to onset of renal replacement therapy and ESKD. Future potential treatments of AS disease progression are evaluated in this review.
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Demosthenous P, Voskarides K, Stylianou K, Hadjigavriel M, Arsali M, Patsias C, Georgaki E, Zirogiannis P, Stavrou C, Daphnis E, Pierides A, Deltas C. X-linked Alport syndrome in Hellenic families: phenotypic heterogeneity and mutations near interruptions of the collagen domain in COL4A5. Clin Genet 2011; 81:240-8. [PMID: 21332469 DOI: 10.1111/j.1399-0004.2011.01647.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The X-linked Alport syndrome (ATS) is caused by mutations in COL4A5 and exhibits a widely variable expression. Usually ATS is heralded with continuous microhematuria which rapidly progresses to proteinuria, hypertension and chronic or end-stage renal disease (ESRD) by adolescence, frequently accompanied by sensorineural deafness and ocular complications. Milder forms of ATS also exist. We studied 42 patients (19M, 23F) of nine Hellenic families suspected clinically of X-linked ATS who presented with marked phenotypic heterogeneity. We identified mutations in COL4A5 in six families. Two males with nonsense mutation E228X reached ESRD by ages 14 and 18. Frameshift mutation 2946delT followed the same course with early onset renal involvement and deafness. However, two males with the milder missense mutation G624D, reached ESRD after 39 years and one patient showed thin basement membrane nephropathy (TBMN). Another 5/8 affected males with missense mutation P628L also developed ESRD between 30 and 57 years, while three exhibit only mild chronic renal failure (CRF). The data support previous findings that certain mutations are associated with milder phenotypes and confirm that mutation G624D may be expressed as TBMN with familial hematuria. Similar conclusions apply for missense mutation P628L. Interestingly, mutations G624D and P628L are near the 12th natural interruption of COL4A5 triple helical domain, which may explain the milder phenotype.
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Affiliation(s)
- P Demosthenous
- Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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Bassareo PP, Marras AR, Mercuro G. Ventricular septal defect in a child with Alport syndrome: a case report. BMC Cardiovasc Disord 2010; 10:48. [PMID: 20920374 PMCID: PMC2958932 DOI: 10.1186/1471-2261-10-48] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/05/2010] [Indexed: 12/16/2022] Open
Abstract
Background Alport syndrome (AS) is a rare inherited disorder characterized by an inflammation of the kidneys and damage to the glomerular capillaries, ultimately leading to renal failure at an early age. To date, rare reports of cardiac involvement in AS have been described, due in the majority of cases to the higher risk of heart conduction abnormalities in these patients, at times requiring implantation of a transcutaneous pacemaker. An increased risk of hypertension is likewise commonly featured. Case presentation We report the case of a 17-year-old female affected by a very severe early form of AS. A previously unreported association of the syndrome with congenital heart disease (CHD), (in this case membranous ventricular septal defect), is also reported. A possible pathophysiological mechanism underlying the concomitant manifestation of these two disorders is suggested. Complications implicated in surgical treatment of CHD are described. Clinical and therapeutic management of AS with cardiovascular involvement are discussed, and a short literature review performed. Conclusions This first report of a cardiovascular association highlights the possible involvement of collagen mutations in the two pathologies. Even when drug-resistance appears to be responsible for the failure to control secondary hypertension in AS, clonidine may represent a safe, effective option in the normalization of high blood pressure.
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Affiliation(s)
- Pier Paolo Bassareo
- Department of Cardiovascular and Neurological Sciences, University of Cagliari, Cagliari, Italy.
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