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Nkoy AB, Ekulu PM, Labarque V, Van den Heuvel LP, Levtchenko EN. HIV-associated nephropathy in children: challenges in a resource-limited setting. Pediatr Nephrol 2023; 38:2509-2521. [PMID: 36472655 DOI: 10.1007/s00467-022-05819-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/26/2022] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
HIV infection remains one of the leading causes of morbidity and mortality worldwide, especially in children living in resource-limited settings. Although the World Health Organization (WHO) recently recommended antiretroviral therapy (ART) initiation upon diagnosis regardless of the number of CD4, ART access remains limited, especially in children living in sub-Saharan Africa (SSA). HIV-infected children who do not receive appropriate ART are at increased risk of developing HIV-associated nephropathy (HIVAN). Although due to genetic susceptibility, SSA is recognized to be the epicenter of HIVAN, limited information is available regarding the burden of HIVAN in children living in Africa. The present review discusses the information available to date on the prevalence, pathogenesis, risk factors, diagnosis, and management of HIVAN in children, focusing on related challenges in a resource-limited setting.
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Affiliation(s)
- Agathe B Nkoy
- Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Pépé M Ekulu
- Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Veerle Labarque
- Department of Pediatric Hematology, University Hospital Leuven, Leuven, Belgium
- Center of Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Lambertus P Van den Heuvel
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium
- Department of Pediatric Nephrology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Elena N Levtchenko
- Laboratory of Pediatric Nephrology, Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.
- Department of Pediatric Nephrology, University Hospital Leuven, Leuven, Belgium.
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Adebayo OC, Van den Heuvel LP, Olowu WA, Levtchenko EN, Labarque V. Sickle cell nephropathy: insights into the pediatric population. Pediatr Nephrol 2022; 37:1231-1243. [PMID: 34050806 DOI: 10.1007/s00467-021-05126-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/10/2021] [Accepted: 05/06/2021] [Indexed: 12/13/2022]
Abstract
The life expectancy of individuals with sickle cell disease has increased over the years, majorly due to an overall improvement in diagnosis and medical care. Nevertheless, this improved longevity has resulted in an increased prevalence of chronic complications such as sickle cell nephropathy (SCN), which poses a challenge to the medical care of the patient, shortening the lifespan of patients by 20-30 years. Clinical presentation of SCN is age-dependent, with kidney dysfunction slowly beginning to develop from childhood, progressing to chronic kidney disease and kidney failure during the third and fourth decades of life. This review explores the epidemiology, pathology, pathophysiology, clinical presentation, and management of SCN by focusing on the pediatric population. It also discusses the factors that can modify SCN susceptibility.
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Affiliation(s)
- Oyindamola C Adebayo
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Lambertus P Van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Wasiu A Olowu
- Pediatric Nephrology and Hypertension Unit, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
| | - Elena N Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium. .,Department of Pediatric Nephrology, University Hospital Leuven, Herestraat 49, Bus 817, 3000, Leuven, Belgium.
| | - Veerle Labarque
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Pediatric Hematology, University Hospital Leuven, Leuven, Belgium
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Adebayo OC, Betukumesu DK, Nkoy AB, Adesoji OM, Ekulu PM, Van den Heuvel LP, Levtchenko EN, Labarque V. Clinical and genetic factors are associated with kidney complications in African children with sickle cell anaemia. Br J Haematol 2021; 196:204-214. [PMID: 34545573 DOI: 10.1111/bjh.17832] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/19/2021] [Accepted: 09/02/2021] [Indexed: 12/11/2022]
Abstract
Clinical and genetic factors have been reported as influencing the development of sickle cell nephropathy (SCN). However, such data remain limited in the paediatric population. In this cross-sectional study, we enrolled 361 sickle cell disease children from the Democratic Republic of Congo. Participants were genotyped for the beta (β)-globin gene, apolipoprotein L1 (APOL1) risk variants, and haem oxygenase-1 (HMOX1) GT-dinucleotide repeats. As markers of kidney damage, albuminuria, hyperfiltration and decreased estimated glomerular filtration with creatinine (eGFRcr) were measured. An association of independent clinical and genetic factors with these markers of kidney damage were assessed via regression analysis. Genetic sequencing confirmed sickle cell anaemia in 326 participants. Albuminuria, hyperfiltration and decreased eGFRcr were present in 65 (20%), 52 (16%) and 18 (5·5%) patients, respectively. Regression analysis revealed frequent blood transfusions, indirect bilirubin and male gender as clinical predictors of SCN. APOL1 high-risk genotype (G1/G1, G2/G2 and G1/G2) was significantly associated with albuminuria (P = 0·04) and hyperfiltration (P = 0·001). HMOX1 GT-dinucleotide long repeats were significantly associated with lower eGFRcr. The study revealed a high burden of kidney damage among Congolese children and provided evidence of the possible role of APOL1 and HMOX1 in making children more susceptible to kidney complications.
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Affiliation(s)
- Oyindamola Christiana Adebayo
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium
| | - DieuMerci Kabasele Betukumesu
- Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Agathe Bikupe Nkoy
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | | | - Pepe Mfutu Ekulu
- Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Lambertus P Van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Nephrology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Elena N Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Veerle Labarque
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Haemato-Oncology, University Hospitals Leuven, Leuven, Belgium
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Ekulu PM, Adebayo OC, Decuypere JP, Bellucci L, Elmonem MA, Nkoy AB, Mekahli D, Bussolati B, van den Heuvel LP, Arcolino FO, Levtchenko EN. Novel Human Podocyte Cell Model Carrying G2/G2 APOL1 High-Risk Genotype. Cells 2021; 10:cells10081914. [PMID: 34440683 PMCID: PMC8391400 DOI: 10.3390/cells10081914] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 02/01/2023] Open
Abstract
Apolipoprotein L1 (APOL1) high-risk genotypes (HRG), G1 and G2, increase the risk of various non-diabetic kidney diseases in the African population. To date, the precise mechanisms by which APOL1 risk variants induce injury on podocytes and other kidney cells remain unclear. Trying to unravel these mechanisms, most studies have used animal or cell models created by gene editing. We developed and characterised conditionally immortalised human podocyte cell lines derived from urine of a donor carrying APOL1 HRG G2/G2. Following induction of APOL1 expression by polyinosinic-polycytidylic acid (poly(I:C)), we assessed functional features of APOL1-induced podocyte dysfunction. As control, APOL1 wild type (G0/G0) podocyte cell line previously generated from a Caucasian donor was used. Upon exposure to poly(I:C), G2/G2 and G0/G0 podocytes upregulated APOL1 expression resulting in podocytes detachment, decreased cells viability and increased apoptosis rate in a genotype-independent manner. Nevertheless, G2/G2 podocyte cell lines exhibited altered features, including upregulation of CD2AP, alteration of cytoskeleton, reduction of autophagic flux and increased permeability in an in vitro model under continuous perfusion. The human APOL1 G2/G2 podocyte cell model is a useful tool for unravelling the mechanisms of APOL1-induced podocyte injury and the cellular functions of APOL1.
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Affiliation(s)
- Pepe M. Ekulu
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Oyindamola C. Adebayo
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Jean-Paul Decuypere
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
| | - Linda Bellucci
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10124 Turin, Italy; (L.B.); (B.B.)
| | - Mohamed A. Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo 11628, Egypt;
| | - Agathe B. Nkoy
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Djalila Mekahli
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Benedetta Bussolati
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10124 Turin, Italy; (L.B.); (B.B.)
| | - Lambertus P. van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatric Nephrology, Radboud University Medical Centre, 6500 Nijmegen, The Netherlands
| | - Fanny O. Arcolino
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Correspondence: ; Tel.: +32-16372647
| | - Elena N. Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
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Jamalpoor A, Othman A, Levtchenko EN, Masereeuw R, Janssen MJ. Molecular Mechanisms and Treatment Options of Nephropathic Cystinosis. Trends Mol Med 2021; 27:673-686. [PMID: 33975805 DOI: 10.1016/j.molmed.2021.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 11/15/2022]
Abstract
Nephropathic cystinosis is a severe, monogenic systemic disorder that presents early in life and leads to progressive organ damage, particularly affecting the kidneys. It is caused by mutations in the CTNS gene, which encodes the lysosomal transporter cystinosin, resulting in intralysosomal accumulation of cystine. Recent studies demonstrated that the loss of cystinosin is associated with disrupted autophagy dynamics, accumulation of distorted mitochondria, and increased oxidative stress, leading to abnormal proliferation and dysfunction of kidney cells. We discuss these molecular mechanisms driving nephropathic cystinosis. Further, we consider how unravelling molecular mechanisms supports the identification and development of new strategies for cystinosis by the use of small molecules, biologicals, and genetic rescue of the disease in vitro and in vivo.
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Affiliation(s)
- Amer Jamalpoor
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, 3584, CG, Utrecht, The Netherlands
| | - Amr Othman
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, 3584, CG, Utrecht, The Netherlands
| | - Elena N Levtchenko
- Department of Pediatric Nephrology & Growth and Regeneration, University Hospitals Leuven & KU Leuven, Leuven, Belgium
| | - Rosalinde Masereeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, 3584, CG, Utrecht, The Netherlands.
| | - Manoe J Janssen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, 3584, CG, Utrecht, The Netherlands.
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Ekulu PM, Nkoy AB, Betukumesu DK, Aloni MN, Makulo JRR, Sumaili EK, Mafuta EM, Elmonem MA, Arcolino FO, Kitetele FN, Lepira FB, van den Heuvel LP, Levtchenko EN. APOL1 Risk Genotypes Are Associated With Early Kidney Damage in Children in Sub-Saharan Africa. Kidney Int Rep 2019; 4:930-938. [PMID: 31317115 PMCID: PMC6612006 DOI: 10.1016/j.ekir.2019.04.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/23/2019] [Accepted: 04/01/2019] [Indexed: 12/11/2022] Open
Abstract
Introduction Apolipoprotein-L1 (APOL1) risk variants G1 and G2 increase the risk of chronic kidney disease (CKD), including HIV-related CKD, among African Americans. However, such data from populations living in Africa, especially children, remain limited. Our research aimed to determine the prevalence of APOL1 risk variants and to assess the association between these variants and early-stage CKD in the general pediatric population and HIV-infected children. Methods In a cross-sectional study, we enrolled 412 children from the general population and 401 HIV-infected children in Kinshasa, Democratic Republic of Congo (DRC). APOL1 high-risk genotype (HRG) was defined by the presence of 2 risk variants (G1/G1, G2/G2, or G1/G2), and low-risk genotype (LRG) by the presence of 0 or 1 risk variants. The main outcome was elevated albuminuria, defined as a urinary albumin/creatinine ratio ≥30 mg/g. Results APOL1 sequence analysis revealed that in the general population, 29 of 412 participants (7.0%) carried HRG, 84 of 412 (20.4%) carried the G1/G0 genotype, and 61 of 412 (14.8%) carried the G2/G0 genotype. In HIV-infected children, 23 of 401 (5.7%) carried HRG, and the same trend as in the general population was observed in regard to the prevalence of LRG. Univariate analysis showed that in the general population, 5 of 29 participants (17.2%) carrying HRG had elevated albuminuria, compared with 35 of 383 (9.0%) with LRG (odds ratio [OR] 2.1, 95% confidence interval [CI] 0.6-6.0; P = 0.13). In HIV-infected children, participants who carried APOL1 HRG had almost 22-fold increased odds of albuminuria compared to those with LRG. Conclusion The APOL1 risk variants are prevalent in children living in DRC. HRG carriers have increased odds of early kidney disease, and infection with HIV dramatically increases this probability.
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Affiliation(s)
- Pepe M Ekulu
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Agathe B Nkoy
- Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Dieumerci K Betukumesu
- Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Michel N Aloni
- Division of Nephrology, Department of Pediatrics, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Jean Robert R Makulo
- Division of Nephrology, Department of Internal Medicine, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Ernest K Sumaili
- Division of Nephrology, Department of Internal Medicine, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Eric M Mafuta
- Department of Biostatistics, Health Public School, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Mohamed A Elmonem
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Fanny O Arcolino
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Faustin N Kitetele
- Division of Infectious Diseases, Department of Pediatrics, Children's Hospital of Kalembelembe, Kinshasa, Democratic Republic of Congo
| | - François B Lepira
- Division of Nephrology, Department of Internal Medicine, University Hospital of Kinshasa, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Lambertus P van den Heuvel
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Elena N Levtchenko
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, University Hospital Leuven, Leuven, Belgium
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van Rijssel AE, Knuijt S, Veys K, Levtchenko EN, Janssen MCH. Swallowing dysfunction in patients with nephropathic cystinosis. Mol Genet Metab 2019; 126:413-415. [PMID: 30685240 DOI: 10.1016/j.ymgme.2019.01.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 01/16/2019] [Accepted: 01/16/2019] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Nephropathic cystinosis is a rare autosomal recessive lysosomal storage disorder caused by mutations in the CTNS gene. Patients with nephropathic cystinosis suffer not only from renal disease but have also other systemic complications like myopathy and swallowing dysfunction. Dysphagia for solid food is mentioned in patients with cystinosis, but in clinical practice swallowing investigations are only performed when the patient has complaints. The aim of this study was to explore the swallowing function in patients with cystinosis by use of the Test of Mastication and Swallowing Solids (TOMASS), and to compare their performance with patients with myotonic dystrophy type 1 - a neuromuscular disease in which dysphagia for solid food is a known problem. METHODS Twenty adult patients with cystinosis (11 men and 9 women, range 19-51 years) and 10 patients with myotonic dystrophy type 1 (5 men and 5 women, range 20-60 years) were included. All cystinosis patients were treated with cysteamine. Data of the two groups were compared with normative data using independent-samples t-tests. In case the variables were not normally distributed, the non-parametric Mann-Whitney U test was used. RESULTS There was a significant difference in the number of bites, masticatory cycles, swallows and total time between the normal values and cystinosis patients. The results of the cystinosis patients were comparable to those of the patients with myotonic dystrophy. DISCUSSION AND CONCLUSION Adult patients with cystinosis have significant dysphagia for solid food. Clinicians treating these patients should be aware of this fact. The TOMASS can be performed easily in clinical practice to investigate whether patients with cystinosis have swallowing dysfunction. The swallowing dysfunction can now be diagnosed by use of a non-invasive, very simple, non-harmful test. It can be discussed whether this should be added to the regular care scheme of cystinosis patients in order to regularly follow-up swallowing function.
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Affiliation(s)
- A E van Rijssel
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - S Knuijt
- Department of Rehabilitation, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - K Veys
- Department of Pediatrics & Department of Growth and Regeneration, University Hospitals Leuven & University of Leuven, Leuven, Belgium
| | - E N Levtchenko
- Department of Pediatrics & Department of Growth and Regeneration, University Hospitals Leuven & University of Leuven, Leuven, Belgium
| | - M C H Janssen
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.
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Elmonem MA, Berlingerio SP, van den Heuvel LP, de Witte PA, Lowe M, Levtchenko EN. Genetic Renal Diseases: The Emerging Role of Zebrafish Models. Cells 2018; 7:cells7090130. [PMID: 30200518 PMCID: PMC6162634 DOI: 10.3390/cells7090130] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
The structural and functional similarity of the larval zebrafish pronephros to the human nephron, together with the recent development of easier and more precise techniques to manipulate the zebrafish genome have motivated many researchers to model human renal diseases in the zebrafish. Over the last few years, great advances have been made, not only in the modeling techniques of genetic diseases in the zebrafish, but also in how to validate and exploit these models, crossing the bridge towards more informative explanations of disease pathophysiology and better designed therapeutic interventions in a cost-effective in vivo system. Here, we review the significant progress in these areas giving special attention to the renal phenotype evaluation techniques. We further discuss the future applications of such models, particularly their role in revealing new genetic diseases of the kidney and their potential use in personalized medicine.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, 11628 Cairo, Egypt.
| | - Sante Princiero Berlingerio
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.
| | - Peter A de Witte
- Laboratory for Molecular Bio-Discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium.
| | - Martin Lowe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK.
| | - Elena N Levtchenko
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
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Di Mise A, Tamma G, Ranieri M, Centrone M, van den Heuvel L, Mekahli D, Levtchenko EN, Valenti G. Activation of Calcium-Sensing Receptor increases intracellular calcium and decreases cAMP and mTOR in PKD1 deficient cells. Sci Rep 2018; 8:5704. [PMID: 29632324 PMCID: PMC5890283 DOI: 10.1038/s41598-018-23732-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 03/13/2018] [Indexed: 12/25/2022] Open
Abstract
Clinical and fundamental research suggest that altered calcium and cAMP signaling might be the most proximal events in ADPKD pathogenesis. Cells from ADPKD cysts have a reduced resting cytosolic calcium [Ca2+]i and increased cAMP levels. CaSR plays an essential role in regulating calcium homeostasis. Its activation is associated with [Ca2+]i increase and cAMP decrease, making CaSR a possible therapeutic target. Human conditionally immortalized Proximal Tubular Epithelial cells (ciPTEC) with stable knockdown of PKD1 (ciPTEC-PC1KD) and ciPTEC generated from an ADPKD1 patient (ciPTEC-PC1Pt) were used as experimental tools. CaSR functional expression was confirmed by studies showing that the calcimimetic NPS-R568 induced a significant increase in [Ca2+]i in ciPTEC-PC1KD and ciPTEC-PC1Pt. Resting [Ca2+]i were significantly lower in ciPTEC-PC1KD with respect to ciPTECwt, confirming calcium dysregulation. As in native cyst cells, significantly higher cAMP levels and mTOR activity were found in ciPTEC-PC1KD compared to ciPTECwt. Of note, NPS-R568 treatment significantly reduced intracellular cAMP and mTOR activity in ciPTEC-PC1KD and ciPTEC-PC1Pt. To conclude, we demonstrated that selective CaSR activation in human ciPTEC carrying PKD1 mutation increases [Ca2+]i, reduces intracellular cAMP and mTOR activity, reversing the principal dysregulations considered the most proximal events in ADPKD pathogenesis, making CaSR a possible candidate as therapeutic target.
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Affiliation(s)
- Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70125, Italy.
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70125, Italy.,Istituto Nazionale di Biostrutture e Biosistemi, Roma, 00136, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70125, Italy
| | - Mariangela Centrone
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70125, Italy
| | - Lambertus van den Heuvel
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, 6525 HP, The Netherlands
| | - Djalila Mekahli
- Department of Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, 3000, Belgium.,Department of Development & Regeneration, University of Leuven (KU Leuven), Leuven, 3000, Belgium
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, 3000, Belgium.,Department of Development & Regeneration, University of Leuven (KU Leuven), Leuven, 3000, Belgium
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, 70125, Italy. .,Istituto Nazionale di Biostrutture e Biosistemi, Roma, 00136, Italy. .,Center of Excellence in Comparative Genomics (CEGBA), University of Bari, Bari, 70125, Italy.
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10
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Veys KR, D'Hauwers KW, van Dongen AJCM, Janssen MC, Besouw MTP, Goossens E, van den Heuvel LP, Wetzels AAMM, Levtchenko EN. First Successful Conception Induced by a Male Cystinosis Patient. JIMD Rep 2017; 38:1-6. [PMID: 28405942 DOI: 10.1007/8904_2017_19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/06/2017] [Accepted: 03/09/2017] [Indexed: 12/17/2022] Open
Abstract
Cystinosis is a rare autosomal recessive lysosomal storage disease characterized by multi-organ cystine accumulation, leading to renal failure and extra-renal organ dysfunction. Azoospermia of unknown origin is the main cause of infertility in all male cystinosis patients. Although spermatogenesis has shown to be intact at the testicular level in some patients, no male cystinosis patient has been reported yet to have successfully induced conception.We present the first successful conception ever reported, induced by a 27-year-old male renal transplant infantile nephropathic cystinosis patient through percutaneous epididymal sperm aspiration (PESA) followed by intracytoplasmatic sperm injection (ICSI). After 36 weeks and 6 days of an uncomplicated pregnancy, a dichorial diamniotic (DCDA) twin was born with an appropriate weight for gestational age and in an apparently healthy status. Moreover, we demonstrate that the sperm of epididymal origin in selected male cystinosis patients can be viable for inducing successful conception.Our observation opens a new perspective in life for many male cystinosis patients whom nowadays have become adults, by showing that despite azoospermia fathering a child can be realized. In addition, our findings raise questions about the possibility of sperm cryopreservation at a young age in these patients.
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Affiliation(s)
- Koenraad R Veys
- Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium. .,Department of Growth and Regeneration, Unit of Organ Systems, KU Leuven, Herestraat 49, 3000, Leuven, Belgium.
| | - Kathleen W D'Hauwers
- Department of Urology, Radboud University Medical Center, Philips van Leydenlaan 15, 6562 EX, Nijmegen, The Netherlands
| | - Angelique J C M van Dongen
- Department of Gynaecology, Radboud University Medical Center, Philips van Leydenlaan 15, 6562 EX, Nijmegen, The Netherlands
| | - Mirian C Janssen
- Department of Internal Medicine, Unit of Metabolic Diseases, Radboud University Medical Center, Philips van Leydenlaan 15, 6562 EX, Nijmegen, The Netherlands
| | - Martine T P Besouw
- Department of Growth and Regeneration, Unit of Organ Systems, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Ellen Goossens
- Department of Reproduction, Biology of the Testis, Genetics and Regenerative Medicine, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090, Brussels, Belgium
| | - Lambert P van den Heuvel
- Department of Growth and Regeneration, Unit of Organ Systems, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Alex A M M Wetzels
- Department of Fertility, Radboud University Medical Center, Philips van Leydenlaan 15, 6562 EX, Nijmegen, The Netherlands
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium.,Department of Growth and Regeneration, Unit of Organ Systems, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
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11
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Ramazani Y, Levtchenko EN, Van Den Heuvel L, Van Schepdael A, Paul P, Ivanova EA, Pastore A, Hartman TM, Price NPJ. Evaluation of carbohydrate-cysteamine thiazolidines as pro-drugs for the treatment of cystinosis. Carbohydr Res 2016; 439:9-15. [PMID: 28033491 DOI: 10.1016/j.carres.2016.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 12/09/2016] [Accepted: 12/12/2016] [Indexed: 10/20/2022]
Abstract
Cystinosis is a genetic disorder caused by malfunction of cystinosin and is characterized by accumulation of cystine. Cysteamine, the medication used in cystinosis, causes halitosis resulting in poor patient compliance. Halitosis is mainly caused by the formation of dimethylsulfide as the final product in the cysteamine metabolism pathway. We have synthesized carbohydrate-cysteamine thiazolidines, and hypothesized that the hydrolytic breakdown of cysteamine-thiazolidines can result in free cysteamine being released in target organs. To examine our hypothesis, we tested these analogs in vitro in patient-derived fibroblasts. Cystinotic fibroblasts were treated with different concentrations of arabinose-cysteamine, glucose-cysteamine and maltose-cysteamine. We demonstrated that the analogs break down into cysteamine extracellularly and might therefore not be fully taken up by the cells under the form of the pro-drug. Potential modifications of the analogs that enable their intracellular rather than extracellular breakdown, is necessary to pursue the potential of these analogs as pro-drugs.
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Affiliation(s)
- Yasaman Ramazani
- Department of Pediatric Nephrology and Growth and Regeneration, University Hospitals Leuven and University of Leuven, UZ Herestraat 49, Box 817, 3000 Leuven, Belgium
| | - Elena N Levtchenko
- Department of Pediatric Nephrology and Growth and Regeneration, University Hospitals Leuven and University of Leuven, UZ Herestraat 49, Box 817, 3000 Leuven, Belgium
| | - Lambertus Van Den Heuvel
- Department of Pediatric Nephrology, Radboud University Medical Center Nijmegen, Nijmegen, The Netherlands
| | - Ann Van Schepdael
- Department of Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, University of Leuven, O&N II Herestraat 49, Box 923, 3000 Leuven, Belgium
| | - Prasanta Paul
- Department of Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, University of Leuven, O&N II Herestraat 49, Box 923, 3000 Leuven, Belgium
| | - Ekaterina A Ivanova
- Department of Pediatric Nephrology and Growth and Regeneration, University Hospitals Leuven and University of Leuven, UZ Herestraat 49, Box 817, 3000 Leuven, Belgium
| | - Anna Pastore
- Laboratory of Metabolomics and Proteomics Bambino Gesu Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165, Rome, Italy
| | - Trina M Hartman
- Agricultural Research Service, U.S. Department of Agriculture, National Center for Agricultural Utilization Research, Peoria, IL 61604, USA
| | - Neil P J Price
- Agricultural Research Service, U.S. Department of Agriculture, National Center for Agricultural Utilization Research, Peoria, IL 61604, USA.
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12
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Ivanova EA, Elmonem MA, Bongaerts I, Luyten T, Missiaen L, van den Heuvel LP, Levtchenko EN, Bultynck G. Ca(2+) signalling in human proximal tubular epithelial cells deficient for cystinosin. Cell Calcium 2016; 60:282-7. [PMID: 27451386 DOI: 10.1016/j.ceca.2016.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/03/2016] [Indexed: 11/17/2022]
Abstract
Nephropathic cystinosis is an autosomal recessive lysosomal storage disorder caused by loss-of-function mutations in the CTNS gene coding for the lysosomal cystine transporter, cystinosin. Recent studies have demonstrated that, apart from cystine accumulation in the lysosomes, cystinosin-deficient cells, especially renal proximal tubular epithelial cells are characterized by abnormal vesicle trafficking and endocytosis, possible lysosomal dysfunction and perturbed intracellular signalling cascades. It is therefore possible that Ca(2+) signalling is disturbed in cystinosis, as it has been demonstrated for other disorders associated with lysosomal dysfunction, such as Gaucher, Niemann-Pick type C and Alzheimer's diseases. In this study we investigated ATP-induced, IP3-induced and lysosomal Ca(2+) release in human proximal tubular epithelial cells derived from control and cystinotic patients. No major dysregulation of intracellular Ca(2+) dynamics was found, although ATP-induced Ca(2+) release appeared slightly sensitized in cystinotic cells compared to control cells. Hence, these subtle changes in Ca(2+) signals elicited by agonists may contribute to the pathogenesis of the disease.
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Affiliation(s)
- Ekaterina A Ivanova
- KU Leuven and UZ Leuven, Department of Pediatric Nephrology & Growth and Regeneration, Leuven, Belgium
| | - Mohamed A Elmonem
- KU Leuven and UZ Leuven, Department of Pediatric Nephrology & Growth and Regeneration, Leuven, Belgium; Cairo University, Faculty of Medicine, Department of Clinical and Chemical Pathology, Cairo, Egypt.
| | - Inge Bongaerts
- KU Leuven and UZ Leuven, Department of Pediatric Nephrology & Growth and Regeneration, Leuven, Belgium
| | - Tomas Luyten
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Ludwig Missiaen
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
| | - Lambertus P van den Heuvel
- KU Leuven and UZ Leuven, Department of Pediatric Nephrology & Growth and Regeneration, Leuven, Belgium; Radboud University Medical Center, Department of Pediatric Nephrology, Nijmegen, The Netherlands
| | - Elena N Levtchenko
- KU Leuven and UZ Leuven, Department of Pediatric Nephrology & Growth and Regeneration, Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, Leuven, Belgium
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13
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Abstract
Cystinosis is a rare, autosomal recessive inherited lysosomal storage disease. It is the most frequent and potentially treatable cause of the inherited renal Fanconi syndrome. If left untreated, renal function rapidly deteriorates towards end-stage renal disease by the end of the first decade of life. Due to its rarity and non-specific presentation, the entity is often not promptly recognized resulting in delayed diagnosis. Two major milestones in cystinosis management, cystine-depleting therapy with cysteamine and renal allograft transplantation, have had a considerable impact on the natural history and prognosis of cystinosis patients. However, due to its significant side effects and a strict 6-hourly dosing regimen, non-adherence to the immediate release of cysteamine bitartrate formulation (Cystagon®) is a major issue that might affect long-term outcome. Recently, a new twice-daily administered delayed-release enteric-coated formula of cysteamine bitartrate (Procysbi(TM)) has been approved by the European Medical Agency for the treatment of cystinosis, and has been shown to be safe and effective. This delayed-release cysteamine has the potential to improve compliance and hence prognosis, through its better dosing regimen, positive impact on quality of life and possibly less side-effects, and is now tested in an ongoing long-term clinical trial. Longer survival of patients with cystinosis makes transition from pediatric to adult-oriented care another challenge in cystinosis management and requires an extended multidisciplinary approach.
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Affiliation(s)
- Koenraad R P Veys
- a Department of Pediatrics, Pediatric Nephrology , University Hospitals Leuven , Belgium
| | - Martine T P Besouw
- b Department of Pediatric Nephrology , University Hospital Ghent , Belgium
| | | | - Maria Van Dyck
- a Department of Pediatrics, Pediatric Nephrology , University Hospitals Leuven , Belgium
| | - Ingele Casteels
- c Department of Ophthalmology , University Hospitals Leuven , Belgium
| | - Elena N Levtchenko
- a Department of Pediatrics, Pediatric Nephrology , University Hospitals Leuven , Belgium
- d Department of Growth & Regeneration , Katholieke Universiteit Leuven , Belgium
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14
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Ivanova EA, van den Heuvel LP, Elmonem MA, De Smedt H, Missiaen L, Pastore A, Mekahli D, Bultynck G, Levtchenko EN. Altered mTOR signalling in nephropathic cystinosis. J Inherit Metab Dis 2016; 39:457-464. [PMID: 26909499 DOI: 10.1007/s10545-016-9919-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/22/2016] [Accepted: 02/02/2016] [Indexed: 11/27/2022]
Abstract
Lysosomes play a central role in regulating autophagy via activation of mammalian target of rapamycin complex 1 (mTORC1). We examined mTORC1 signalling in the lysosomal storage disease nephropathic cystinosis (MIM 219800), in which accumulation of autophagy markers has been previously demonstrated. Cystinosis is caused by mutations in the lysosomal cystine transporter cystinosin and initially affects kidney proximal tubules causing renal Fanconi syndrome, followed by a gradual development of end-stage renal disease and extrarenal complications. Using proximal tubular kidney cells obtained from healthy donors and from cystinotic patients, we demonstrate that cystinosin deficiency is associated with a perturbed mTORC1 signalling, delayed reactivation of mTORC1 after starvation and abnormal lysosomal retention of mTOR during starvation. These effects could not be reversed by treatment with cystine-depleting drug cysteamine. Altered mTORC1 signalling can contribute to the development of proximal tubular dysfunction in cystinosis and points to new possibilities in therapeutic intervention through modulation of mTORC-dependent signalling cascades.
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Affiliation(s)
- Ekaterina A Ivanova
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
| | - Lambertus P van den Heuvel
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mohamed A Elmonem
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Humbert De Smedt
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Ludwig Missiaen
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Anna Pastore
- Laboratory of Proteomics and Metabolomics, Children's Hospital and Research Institute "Bambino Gesù" IRCCS, Rome, Italy
| | - Djalila Mekahli
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium
| | - Greet Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Elena N Levtchenko
- Department of Growth and Regeneration, KU Leuven and University Hospitals Leuven, UZ Herestraat 49, 3000, Leuven, Belgium.
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15
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Ivanova EA, Arcolino FO, Elmonem MA, Rastaldi MP, Giardino L, Cornelissen EM, van den Heuvel LP, Levtchenko EN. Cystinosin deficiency causes podocyte damage and loss associated with increased cell motility. Kidney Int 2016; 89:1037-1048. [PMID: 27083281 DOI: 10.1016/j.kint.2016.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 12/22/2015] [Accepted: 01/07/2016] [Indexed: 12/14/2022]
Abstract
The involvement of the glomerulus in the pathogenesis of cystinosis, caused by loss-of-function mutations in cystinosin (CTNS, 17p13), is a matter of controversy. Although patients with cystinosis demonstrate glomerular lesions and high-molecular-weight proteinuria starting from an early age, a mouse model of cystinosis develops only signs of proximal tubular dysfunction. Here we studied podocyte damage in patients with cystinosis by analyzing urinary podocyte excretion and by in vitro studies of podocytes deficient in cystinosin. Urine from patients with cystinosis presented a significantly higher amount of podocytes compared with controls. In culture, cystinotic podocytes accumulated cystine compatible with cystinosin deficiency. The expression of podocyte specific genes CD2AP, podocalyxin, and synaptopodin and of the WT1 protein was evident in all cell lines. Conditionally immortalized podocyte lines of 2 patients with different CTNS mutations had altered cytoskeleton, impaired cell adhesion sites, and increased individual cell motility. Moreover, these cells showed enhanced phosphorylation of both Akt1 and Akt2 (isoforms of protein kinase B). Inhibition of Akt by a specific inhibitor (Akti inhibitor 1/2) resulted in normalization of the hypermotile phenotype. Thus, our study extends the list of genetic disorders causing podocyte damage and provides the evidence of altered cell signaling cascades resulting in impaired cell adhesion and enhanced cell motility in cystinosis.
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Affiliation(s)
- Ekaterina A Ivanova
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Fanny O Arcolino
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Mohamed A Elmonem
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium; Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Maria P Rastaldi
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and Fondazione D'Amico, Milano, Italy
| | - Laura Giardino
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and Fondazione D'Amico, Milano, Italy
| | - Elisabeth M Cornelissen
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Lambertus P van den Heuvel
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium; Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Elena N Levtchenko
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium.
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Besouw MTP, Van Dyck M, Cassiman D, Claes KJ, Levtchenko EN. Management dilemmas in pediatric nephrology: Cystinosis. Pediatr Nephrol 2015; 30:1349-60. [PMID: 25956701 DOI: 10.1007/s00467-015-3117-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 12/17/2022]
Abstract
BACKGROUND Cystinosis is a rare, inherited autosomal recessive disease caused by the accumulation of free cystine in lysosomes. It is treated by the administration of cysteamine, which should be monitored by trough white blood cell (WBC) cystine measurements to ensure effective treatment. CASE-DIAGNOSIS/TREATMENT The index case had an older brother who had previously been diagnosed with cystinosis, allowing early diagnosis of the index case at the age of 5 months. Cysteamine therapy was started at the age of 3 years; however, monitoring of WBC cystine levels did not occur on a regular basis during most of his life. Growth retardation improved after correction of electrolyte disturbances, the initiation of cysteamine therapy and treatment with recombinant human growth hormone. Renal replacement therapy was started at the age of 11 years, and renal transplantation was performed at the age of 12 years. Extra-renal cystine accumulation caused multiple endocrinopathies (including adrenal insufficiency, hypothyroidism and primary hypogonadism), neurological symptoms, pancytopenia owing to splenomegaly and portal hypertension due to nodular regenerative hyperplasia, aggravated by splenic vein thrombosis and partial portal vein thrombosis. The patient died of diffuse intra-abdominal bleeding caused by severe portal hypertension. CONCLUSION Cysteamine treatment should be started as early as possible, and dosage should be monitored and adapted based on trough WBC cystine levels. RELEVANT INTERNATIONAL GUIDELINE Emma F et al. (2014) Nephropathic cystinosis: an international consensus document. Nephrol Dial Transplant 29:iv87-iv94.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, University Hospital Ghent, De Pintelaan 185, 9000, Ghent, Belgium,
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18
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Di Mise A, Tamma G, Ranieri M, Svelto M, Heuvel BVD, Levtchenko EN, Valenti G. Conditionally immortalized human proximal tubular epithelial cells isolated from the urine of a healthy subject express functional calcium-sensing receptor. Am J Physiol Renal Physiol 2015; 308:F1200-6. [PMID: 25656364 DOI: 10.1152/ajprenal.00352.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 02/03/2015] [Indexed: 02/08/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor, which plays an essential role in regulating Ca(2+) homeostasis. Here we show that conditionally immortalized proximal tubular epithelial cell line (ciPTEC) obtained by immortalizing and subcloning cells exfoliated in the urine of a healthy subject expresses functional endogenous CaSR. Immunolocalization studies of polarized ciPTEC revealed the apical localization of the receptor. By Western blotting of ciPTEC lysates, both monomeric and dimeric forms of CaSR at 130 and ∼250 kDa, respectively, were detected. Functional studies indicated that both external calcium and the positive CaSR allosteric modulator, NPS-R568, induced a significant increase in cytosolic calcium, proving a high sensitivity of the endogenous receptor to its agonists. Calcium depletion from the endoplasmic reticulum using cyclopiazonic acid abolished the increase in cytosolic calcium elicited by NPS-R568, confirming calcium exit from intracellular stores. Activation of CaSR by NPS-R significantly reduced the increase in cAMP elicited by forskolin (FK), a direct activator of adenylate cyclase, further confirming the functional expression of the receptor in this cell line. CaSR expressed in ciPTEC was found to interact with Gq as a downstream effector, which in turn can cause release of calcium from intracellular stores via phospholipase C activation. We conclude that human proximal tubular ciPTEC express functional CaSR and respond to its activation with a release of calcium from intracellular stores. These cell lines represent a valuable tool for research into the disorder associated with gain or loss of function of the CaSR by producing cell lines from patients.
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Affiliation(s)
- Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Maria Svelto
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy
| | - Bert van den Heuvel
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; and
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy;
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Abstract
Cystinosis is an autosomal recessive inherited lysosomal storage disease. It is characterized by generalized proximal tubular dysfunction known as renal Fanconi syndrome and causes end-stage renal disease by the age of about 10 years if left untreated. Extrarenal organs are also affected, including the thyroid gland, gonads, pancreas, liver, muscle, and brain. Treatment consists of administration of cysteamine, resulting in depletion of cystine that is trapped inside the lysosomes. Since cysteamine has a short half-life, it should be administered every 6 hours. Recently, a new delayed-release formulation was marketed, that should be administered every 12 hours. The first studies comparing both cysteamine formulations show comparable results regarding white blood cell cystine depletion (which serves as a measure for cystine accumulation in the body), while a slightly lower daily dose of cysteamine can be used.
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Affiliation(s)
- Martine Tp Besouw
- Department of Pediatric Nephrology, University Hospitals Leuven, Belgium ; Laboratory of Pediatrics, Catholic University Leuven, Leuven, Belgium
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospitals Leuven, Belgium ; Laboratory of Pediatrics, Catholic University Leuven, Leuven, Belgium
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20
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Besouw MTP, Emma F, Levtchenko EN. Management of nephropathic cystinosis. Expert Opin Orphan Drugs 2013. [DOI: 10.1517/21678707.2013.855634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Besouw MTP, Schneider J, Janssen MC, Greco M, Emma F, Cornelissen EA, Desmet K, Skovby F, Nobili F, Lilien MR, De Paepe A, Malfait F, Symoens S, van den Heuvel LP, Levtchenko EN. Copper deficiency in patients with cystinosis with cysteamine toxicity. J Pediatr 2013; 163:754-60. [PMID: 23651769 DOI: 10.1016/j.jpeds.2013.03.078] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 01/09/2013] [Accepted: 03/28/2013] [Indexed: 12/13/2022]
Abstract
OBJECTIVES To assess whether copper deficiency plays a role in the recently described cysteamine toxicity in patients with cystinosis, and to examine whether polymorphisms in copper transporters, lysyl oxidase, and/or type I procollagen genes could be responsible for the occurrence of cysteamine toxicity in a small subset of patients with cystinosis. STUDY DESIGN Thirty-six patients with cystinosis were included: 22 with Fanconi syndrome (including 7 with cysteamine toxicity), 12 after renal transplantation, 1 receiving hemodialysis, and 1 with ocular cystinosis. Serum copper and ceruloplasmin levels and urinary copper/creatinine ratio were measured. Genes ATP7A and CTR1 (encoding copper transporters), LOX (encoding lysyl oxidase), and COL1A1 and COL1A2 (encoding type I procollagen) were analyzed in patients with (n = 6) and without (n = 5) toxicity. Fibroblast (pro)collagen synthesis was compared in patients with (n = 3) and those without (n = 2) cysteamine toxicity. RESULTS All 22 patients with Fanconi syndrome had increased urinary copper excretion. Serum copper and ceruloplasmin levels were decreased in 9 patients, including all 7 patients with cysteamine toxicity. No specific sequence variations were associated with toxicity. All fibroblasts exhibited normal (pro)collagen synthesis. CONCLUSION Patients with cystinosis with cysteamine toxicity demonstrate copper deficiency. This can cause decreased activity of lysyl oxidase, the enzyme that generates the aldehydes required for collagen cross-linking. Thus, copper supplementation might prevent cysteamine toxicity.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, Leuven University Hospital, Leuven, Belgium.
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22
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Monnens LA, Van de Walle J, Knoll J, Levtchenko EN. In memoriam: Professor Cornelis Schroder--8 April 1951-19 September 2012. Pediatr Nephrol 2013; 28:833-4. [PMID: 23436175 DOI: 10.1007/s00467-013-2422-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 01/18/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Leo A Monnens
- Department of Physiology, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands
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23
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Besouw MTP, Van Dyck M, Francois I, Van Hoyweghen E, Levtchenko EN. Detailed studies of growth hormone secretion in cystinosis patients. Pediatr Nephrol 2012; 27:2123-2127. [PMID: 22664570 DOI: 10.1007/s00467-012-2213-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Cystinosis is an autosomal recessive disorder characterized by intralysosomal cystine accumulation. Growth retardation is more pronounced in cystinosis than in other chronic kidney diseases and is mostly not corrected by cysteamine. METHODS Growth was evaluated in nine cystinosis patients, all treated with cysteamine, both after cysteamine and recombinant human growth hormone (rhGH) therapy initiation. Growth hormone (GH) secretion was studied by nocturnal GH measurements in four of nine patients and by glucagon test in four of nine patients. RESULTS RhGH was administered to seven of nine patients. At rhGH initiation, height was below -2 SDS in five of seven patients, final height was above -2 SDS in six of seven. In two patients not treated with rhGH, final height remained below -4 SDS despite cysteamine treatment being started at the age of 6.1 and 8.1 years, respectively. Nocturnal GH secretion was normal in all patients. Glucagon tests revealed GH deficiency in one patient; two of four patients had abnormal GH peak timing. CONCLUSIONS We present the first reported case of GH deficiency in cystinosis. Although no overt GH deficiency was detected in other patients, abnormal GH peak timing can indicate a subclinical GH secretion problem. RhGH significantly improved growth in cystinosis patients and should be initiated early in life.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium.
| | - Maria Van Dyck
- Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Inge Francois
- Department of Pediatric Endocrinology, University Hospitals Leuven, Leuven, Belgium
| | | | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
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24
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Besouw MTP, van Pelt AMM, Gaide Chevronnay HP, Courtoy PJ, Pastore A, Goossens E, Devuyst O, Antignac C, Levtchenko EN. Studying nonobstructive azoospermia in cystinosis: histologic examination of testes and epididymis and sperm analysis in a Ctns⁻/⁻ mouse model. Fertil Steril 2012; 98:162-5. [PMID: 22578532 DOI: 10.1016/j.fertnstert.2012.03.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 03/16/2012] [Accepted: 03/27/2012] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To study the pathogenesis of male infertility in cystinosis due to nonobstructive azoospermia, using a Ctns(-/-) mouse model. DESIGN Observational case-control study. SETTING Academic research laboratory. ANIMAL(S) Male C57BL/6 Ctns(-/-) mice were compared with C57BL/6 wild-type (wt) mice. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Fertility was studied using litter size (n = 3 vs. n = 2). After animals were sacrificed, testes, epididymis, and vas deferens were removed for testicular cystine measurements (n = 5 vs. n = 6), histologic studies (n = 3 vs. n = 3), and sperm analysis (n = 3 vs. n = 3). RESULT(S) Mean testicular cystine content was significantly higher in Ctns(-/-) mice compared with wt mice (26.6 ± 1.22 vs. 0.1 ± 0.01 nmol cystine/mg protein). Testes of Ctns(-/-) mice had lower weight compared with wt mice (0.096 ± 0.009 g vs. 0.112 ± 0.004 g), but mice fertility was similar (litter size 6.6 ± 1.4 vs. 6.3 ± 2.6 pups). Neither histologic nor sperm abnormalities were found. CONCLUSION(S) The Ctns(-/-) mouse model generated on C57BL/6 background is not suitable for clarifying the pathogenesis of male infertility in cystinosis. The etiology of nonobstructive azoospermia in these patients remains unclear.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium.
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25
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Mekahli D, Sammels E, Luyten T, Welkenhuyzen K, van den Heuvel LP, Levtchenko EN, Gijsbers R, Bultynck G, Parys JB, De Smedt H, Missiaen L. Polycystin-1 and polycystin-2 are both required to amplify inositol-trisphosphate-induced Ca2+ release. Cell Calcium 2012; 51:452-8. [PMID: 22456092 DOI: 10.1016/j.ceca.2012.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 02/27/2012] [Accepted: 03/02/2012] [Indexed: 12/31/2022]
Abstract
Autosomal dominant polycystic kidney disease is caused by loss-of-function mutations in the PKD1 or PKD2 genes encoding respectively polycystin-1 and polycystin-2. Polycystin-2 stimulates the inositol trisphosphate (IP(3)) receptor (IP(3)R), a Ca(2+)-release channel in the endoplasmic reticulum (ER). The effect of ER-located polycystin-1 is less clear. Polycystin-1 has been reported both to stimulate and to inhibit the IP(3)R. We now studied the effect of polycystin-1 and of polycystin-2 on the IP(3)R activity under conditions where the cytosolic Ca(2+) concentration was kept constant and the reuptake of released Ca(2+) was prevented. We also studied the interdependence of the interaction of polycystin-1 and polycystin-2 with the IP(3)R. The experiments were done in conditionally immortalized human proximal-tubule epithelial cells in which one or both polycystins were knocked down using lentiviral vectors containing miRNA-based short hairpins. The Ca(2+) release was induced in plasma membrane-permeabilized cells by various IP(3) concentrations at a fixed Ca(2+) concentration under unidirectional (45)Ca(2+)-efflux conditions. We now report that knock down of polycystin-1 or of polycystin-2 inhibited the IP(3)-induced Ca(2+) release. The simultaneous presence of the two polycystins was required to fully amplify the IP(3)-induced Ca(2+) release, since the presence of polycystin-1 alone or of polycystin-2 alone did not result in an increased Ca(2+) release. These novel findings indicate that ER-located polycystin-1 and polycystin-2 operate as a functional complex. They are compatible with the view that loss-of-function mutations in PKD1 and in PKD2 both cause autosomal dominant polycystic kidney disease.
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Affiliation(s)
- D Mekahli
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven Campus Gasthuisberg O&N I, Belgium
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26
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Besouw MTP, Bowker R, Dutertre JP, Emma F, Gahl WA, Greco M, Lilien MR, McKiernan J, Nobili F, Schneider JA, Skovby F, van den Heuvel LP, Van't Hoff WG, Levtchenko EN. Cysteamine toxicity in patients with cystinosis. J Pediatr 2011; 159:1004-11. [PMID: 21784456 DOI: 10.1016/j.jpeds.2011.05.057] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 05/04/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To report new adverse effects of cysteamine. STUDY DESIGN Detailed clinical information was obtained from the patients' physicians. RESULTS New adverse events were reported in 8 of 550 patients with cystinosis treated with cysteamine in Europe during the last 5 years. Detailed clinical information was not available for 2 of these patients, 1 of whom died from cerebral ischemia. The 6 evaluable patients developed vascular elbow lesions (6/6), neurologic symptoms (1/6), bone and muscle pain (2/6), and/or skin striae (2/6). Analysis of biopsy specimens from the elbow lesions demonstrated angioendotheliomatosis with irregular collagen fibers. In 3 of the 6 patients, the daily cysteamine dose exceeded the recommended maximum of 1.95 g/m(2)/day. Dose reduction led to improvement of signs and symptoms in all 6 patients, suggesting a causal relationship with cysteamine administration. CONCLUSION Cysteamine administration can be complicated by the development of skin, vascular, neurologic, muscular, and bone lesions. These lesions improve after cysteamine dose reduction. Doses >1.95 g/m(2)/day should be prescribed with great caution, but underdosing is not advocated.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, Laboratory of Pediatrics, University Hospitals Leuven, Leuven, Belgium
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27
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Van Stralen KJ, Emma F, Jager KJ, Verrina E, Schaefer F, Laube GF, Lewis MA, Levtchenko EN. Improvement in the renal prognosis in nephropathic cystinosis. Clin J Am Soc Nephrol 2011; 6:2485-91. [PMID: 21868618 DOI: 10.2215/cjn.02000311] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Nephropathic cystinosis (NC) is an autosomal recessive disorder occurring in one to two per 100,000 newborns. Because of the rarity of NC, long-term outcome data are scarce. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS 245 NC patients from 18 countries provided data to the ESPN/ERA-EDTA registry. We matched NC patients on renal replacement therapy (RRT) to non-NC children on RRT. RESULTS Between 1979 and 2008, mean age at the start of RRT among NC children increased by 0.15 year per calendar year (95% confidence interval, 0.10 to 0.21) from 8.8 to 12.7 years, whereas we did not observe this in non-NC children. Five-year survival after the start of RRT improved in NC patients from 86.1% (before 1990) to 100% (since 2000) as compared with the control population (89.6% and 94.0%). NC patients received a renal allograft more often (relative risk, 1.09; 95% confidence interval, 1.00 to 1.17) as compared with matched RRT children, and 5-year graft survival was better (94.0% versus 84.0%). NC dialysis patients were less often hypertensive than non-NC children matched for age, country, and dialysis modality (42.7% versus 51.7%) and had lower parathyroid hormone levels (median, 56 versus 140 pg/ml). Although height at start of RRT slightly improved during the past decade, children with NC remained significantly shorter than non-NC children at the start of RRT. CONCLUSIONS We demonstrated improved survival of the renal function as well as better patient and graft survival after the start of RRT in a large European cohort of NC patients over the last two decades.
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Affiliation(s)
- Karlijn J Van Stralen
- European Society for Paediatric Nephrology/European Renal Association and European Dialysis and Transplant Association Registry, Department of Medical Informatics, Academic Medical Center, Amsterdam, The Netherlands.
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28
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Besouw MTP, Holewijn S, Levtchenko EN, Janssen MCH. Non-invasive measurements of atherosclerosis in adult cystinosis patients. J Inherit Metab Dis 2011; 34:811-8. [PMID: 21305353 PMCID: PMC3109266 DOI: 10.1007/s10545-011-9281-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 12/28/2010] [Accepted: 01/13/2011] [Indexed: 01/15/2023]
Abstract
BACKGROUND Cystinosis is characterized by intralysosomal cystine accumulation, causing end stage renal disease around 10 years of age if not treated with cysteamine. Cystine accumulation in blood vessels might increase atheroma formation or arterial stiffness and therefore increase the risk for cardiovascular disease (CVD). This study aimed to investigate the risk for CVD by non-invasive measures of atherosclerosis (NIMA) and to evaluate the effect of cysteamine treatment. PATIENTS AND METHODS Thirteen Dutch adult cystinosis patients were included. White blood cell (WBC) cystine levels, glomerular filtration rate (GFR) and concommitant medications were obtained from medical records. NIMA included carotid intima-media thickness (cIMT, n = 13), pulse wave velocity (PWV, n = 8) and pulse wave analysis (PWA, n = 6). RESULTS GFR ranged between 4-95 mL/min/1.73 m². All but one patient were treated with cysteamine, mean WBC cystine values ranged between 0.34-1.64 nmol cystine/mg protein, 8 patients had mean WBC cystine levels <1 nmol cystine/mg protein. When compared to healthy subjects, cIMT and PWV levels were above normal values in 1 patient for each measure. PWA measurements showed high augmentation index in three patients who did not receive lipid-lowering medication. When corrected for renal function, cIMT and PWV levels were within the normal range. CONCLUSION Young adult cystinosis patients treated with cysteamine have no additional risk for CVD when compared to patients with chronic kidney disease of other causes.
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Affiliation(s)
- Martine T. P. Besouw
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Suzanne Holewijn
- Department of Internal Medicine, Radboud University Medical Centre, 463 PO box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Elena N. Levtchenko
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Mirian C. H. Janssen
- Department of Internal Medicine, Radboud University Medical Centre, 463 PO box 9101, 6500 HB, Nijmegen, The Netherlands
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Abstract
Here we describe the case of a patient followed from birth because of a positive family history for apparent mineralocorticoid excess (AME) in an older brother. The patient, a girl, had normal serum electrolyte and blood pressure measurements in the first months after birth. Not until the age of 11 months did she develop anorexia and failure to thrive in combination with hypertension, hypokalemia, and metabolic alkalosis, which are consistent with the diagnosis of AME. This diagnosis was confirmed by mutation analysis of the HSD11B2 gene (C1228T). Treatment with amiloride and furosemide electrolyte disturbances normalized her blood pressure. At the age of 19 years she unexpectedly suffered a stroke. Additional investigations revealed no accepted risk factor for stroke. We discuss the possible underlying mechanisms for the delayed manifestation of hypertension and electrolyte disturbances in AME, propose an additional explanation for the stroke in this patient, and advise treatment with a mineralocorticoid receptor antagonist to reduce stroke risk in patients with AME.
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Affiliation(s)
- Noël B B Knops
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium.
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30
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Wamelink MMC, Struys EA, Jansen EEW, Blom HJ, Vilboux T, Gahl WA, Kömhoff M, Jakobs C, Levtchenko EN. Elevated concentrations of sedoheptulose in bloodspots of patients with cystinosis caused by the 57-kb deletion: implications for diagnostics and neonatal screening. Mol Genet Metab 2011; 102:339-42. [PMID: 21195649 DOI: 10.1016/j.ymgme.2010.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 12/03/2010] [Accepted: 12/03/2010] [Indexed: 10/18/2022]
Abstract
Cystinosis is an autosomal recessive lysosomal storage disease caused by mutations in CTNS. The most prevalent CTNS mutation is a homozygous 57-kb deletion that also includes an adjacent gene named SHPK (CARKL), encoding sedoheptulokinase. Patients with this deletion have elevated urinary concentrations of sedoheptulose. Using derivatisation with pentafluorobenzyl hydroxylamine and liquid chromatography-tandem mass spectrometry (LC-MS/MS), we developed a new sensitive method for the quantification of sedoheptulose in dried blood spots. This method can be utilized as a quick screening test to detect cystinosis patients homozygous for the 57-kb deletion in CTNS; which is the most common mutation of cystinosis. Sedoheptulose concentrations in the deleted patients were 6 to 23 times above the upper limit for controls. The assessment of sedoheptulose in a bloodspot from a known cystinosis patient homozygous for the 57-kb deletion retrieved from the Dutch neonatal screening program showed that sedoheptulose was already elevated in the neonatal period. There was no overlap in sedoheptulose levels between cystinosis patients homozygous for the 57-kb deletion and cystinosis patients not homozygous for this deletion. Our presented method can be used prior to mutation analysis to detect cystinosis patients homozygous for the 57-kb deletion. We feel that the presented method enables fast (pre)-symptomatic detection of cystinosis patients homozygous for the 57-kb deletion, allowing early treatment.
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Affiliation(s)
- M M C Wamelink
- VU University Medical Center, Department of Clinical Chemistry, Metabolic Unit, Amsterdam, The Netherlands.
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31
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Wilmer MJ, Kluijtmans LAJ, van der Velden TJ, Willems PH, Scheffer PG, Masereeuw R, Monnens LA, van den Heuvel LP, Levtchenko EN. Cysteamine restores glutathione redox status in cultured cystinotic proximal tubular epithelial cells. Biochim Biophys Acta Mol Basis Dis 2011; 1812:643-51. [PMID: 21371554 DOI: 10.1016/j.bbadis.2011.02.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2010] [Revised: 01/28/2011] [Accepted: 02/22/2011] [Indexed: 11/28/2022]
Abstract
Recent evidence implies that impaired metabolism of glutathione has a role in the pathogenesis of nephropathic cystinosis. This recessive inherited disorder is characterized by lysosomal cystine accumulation and results in renal Fanconi syndrome progressing to end stage renal disease in the majority of patients. The most common treatment involves intracellular cystine depletion by cysteamine, delaying the development of end stage renal disease by a yet elusive mechanism. However, cystine depletion does not arrest the disease nor cures Fanconi syndrome in patients, indicating involvement of other yet unknown pathologic pathways. Using a newly developed proximal tubular epithelial cell model from cystinotic patients, we investigate the effect of cystine accumulation and cysteamine on both glutathione and ATP metabolism. In addition to the expected increase in cystine and defective sodium-dependent phosphate reabsorption, we observed less negative glutathione redox status and decreased intracellular ATP levels. No differences between control and cystinosis cell lines were observed with respect to protein turnover, albumin uptake, cytosolic and mitochondrial ATP production, total glutathione levels, protein oxidation and lipid peroxidation. Cysteamine treatment increased total glutathione in both control and cystinotic cells and normalized cystine levels and glutathione redox status in cystinotic cells. However, cysteamine did not improve decreased sodium-dependent phosphate uptake. Our data implicate that cysteamine increases total glutathione and restores glutathione redox status in cystinosis, which is a positive side-effect of this agent next to cystine depletion. This beneficial effect points to a potential role of cysteamine as anti-oxidant for other renal disorders associated with enhanced oxidative stress.
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Affiliation(s)
- Martijn J Wilmer
- Laboratory of Genetic Endocrine and Metabolic Diseases, Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, The Netherlands
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Abstract
Renal proximal tubules are highly sensitive to ischemic and toxic insults and are affected in diverse genetic disorders, of which nephropathic cystinosis is the most common. The disease is caused by mutations in the CTNS gene, encoding the lysosomal cystine transporter cystinosin, and is characterized by accumulation of cystine in the lysosomes throughout the body. In the majority of the patients, this leads to generalized proximal tubular dysfunction (also called DeToni-Debré-Fanconi syndrome) in the first year and progressive renal failure during the first decade. Extrarenal organs are affected by cystinosis as well, with clinical symptoms manifesting mostly after 10 yr of age. The cystine-depleting agent cysteamine significantly improves life expectancy of patients with cystinosis, but offers no cure, pointing to the complexity of the disease mechanism. In this review, current knowledge on the pathogenesis of cystinosis is described and placed in perspective of future research.
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Affiliation(s)
- Martijn J Wilmer
- Dept. of Pediatric Nephrology, Univ. Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
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33
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Taranta A, Wilmer MJ, van den Heuvel LP, Bencivenga P, Bellomo F, Levtchenko EN, Emma F. Analysis of CTNS gene transcripts in nephropathic cystinosis. Pediatr Nephrol 2010; 25:1263-7. [PMID: 20352457 PMCID: PMC2874020 DOI: 10.1007/s00467-010-1502-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 02/23/2010] [Accepted: 03/01/2010] [Indexed: 11/30/2022]
Abstract
Nephropathic cystinosis (NC) is an autosomal recessive disorder caused by mutations of the CTNS gene that encodes for a cystine transmembrane transporter. Several mutations have been described in the coding and promoter regions of the CTNS gene in affected individuals. We selected three patients with NC from two unrelated families, in whom sequence analysis of the CTNS gene detected only one or no mutations. Total RNA was isolated from peripheral blood mononuclear cells or fibroblasts and CTNS transcripts were analyzed. We observed a skipping of exon 5 (85 bp) in two siblings and an intron 9 retention of 75 bp associated with partial replication of exon 9 in the third patient. Genomic DNA analysis of intron regions surrounding exon 5 showed a point mutation in the hypothetical lariat branch site of intron 4 at position -24 (c.141-24 T > C) in the first two patients and a duplication of 266 bp including a part of exon and intron 9 in the third patient. Analysis of CTNS gene transcripts allowed identification of mutations in patients in whom CTNS mutations could not be detected by traditional DNA sequencing. These results support the hypothesis that cystinosis is a monogenic disorder.
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Affiliation(s)
- Anna Taranta
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children's Hospital and Research Institute, Piazza S. Onofrio, 4, 00165, Rome, Italy.
| | - Martijn J. Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Lambert P. van den Heuvel
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands ,Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Paola Bencivenga
- Laboratory of Scientific Research, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Francesco Bellomo
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children’s Hospital and Research Institute, Piazza S. Onofrio, 4, 00165 Rome, Italy
| | - Elena N. Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Francesco Emma
- Department of Nephrology and Urology, Division of Nephrology, Bambino Gesù Children’s Hospital and Research Institute, Piazza S. Onofrio, 4, 00165 Rome, Italy
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34
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Cairo ER, Swarts HGP, Wilmer MJG, Willems PHGM, Levtchenko EN, De Pont JJHHM, Koenderink JB. FXYD2 and Na,K-ATPase expression in isolated human proximal tubular cells: disturbed upregulation on renal hypomagnesemia? J Membr Biol 2009; 231:117-24. [PMID: 19865785 PMCID: PMC2776943 DOI: 10.1007/s00232-009-9210-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 10/08/2009] [Indexed: 11/05/2022]
Abstract
Autosomal dominant renal hypomagnesemia (OMIM 154020), associated with hypocalciuria, has been linked to a 121G to A mutation in the FXYD2 gene. To gain insight into the molecular mechanisms linking this mutation to the clinical phenotype, we studied isolated proximal tubular cells from urine of a patient and a healthy subject. Cells were immortalized and used to assess the effects of hypertonicity-induced overexpression of FXYD2 on amount, activity and apparent affinities for Na+, K+ and ATP of Na,K-ATPase. Both cell lines expressed mRNA for FXYD2a and FXYD2b, and patient cells contained both the wild-type and mutated codons. FXYD2 protein expression was lower in patient cells and could be increased in both cell lines upon culturing in hyperosmotic medium but to a lesser extent in patient cells. Similarly, hyperosmotic culturing increased Na,K-ATPase protein expression and ATP hydrolyzing activity but, again, to a lesser extent in patient cells. Apparent affinities of Na,K-ATPase for Na+, K+ and ATP did not differ between patient and control cells or after hyperosmotic induction. We conclude that human proximal tubular cells respond to a hyperosmotic challenge with an increase in FXYD2 and Na,K-ATPase protein expression, though to a smaller absolute extent in patient cells.
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Affiliation(s)
- Edinio R Cairo
- Department of Biochemistry, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
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Kyrieleis HA, Löwik MM, Pronk I, Cruysberg HR, Kremer JA, Oyen WJ, van den Heuvel BL, Wetzels JF, Levtchenko EN. Long-term outcome of biopsy-proven, frequently relapsing minimal-change nephrotic syndrome in children. Clin J Am Soc Nephrol 2009; 4:1593-600. [PMID: 19808243 PMCID: PMC2758253 DOI: 10.2215/cjn.05691108] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 07/30/2009] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND OBJECTIVES Frequently relapsing and steroid-dependent minimal-change nephrotic syndrome (MCNS) that originates in childhood can persist after puberty in >20% of patients. These patients require immunosuppressive treatment during several decades of their life. We examined long-term adverse effects of persistent nephrotic syndrome and immunosuppressive medications, focusing on renal function, growth, obesity, osteoporosis, hypertension, ocular complications, and fertility in adult patients with biopsy-proven childhood-onset MCNS. Molecular analysis was performed to evaluate a possible association of a complicated course of MCNS with podocyte gene mutations. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We performed a prospective clinical examination of 15 adult patients that included serum and urine analysis; dual-energy x-ray absorptiometry; ophthalmologic examination; semen examination; and molecular analysis of NPHS1, NPHS2, CD2AP, and ACTN4 genes. RESULTS All patients had normal GFR. Most frequent long-term complications were hypertension (in seven of 15 patients) and osteoporosis in one third of patients. Oligozoospermia was found in one patient, reduced sperm motility in four of eight patients, and teratozoospermia in six of eight patients. Ophthalmologic examination revealed myopia in 10 of 15 patients and cataract in three of 15 patients. CONCLUSIONS Children with MCNS that persists after puberty are at risk for complications such as osteoporosis, hypertension, cataract, and sperm abnormalities. Our study underscores a need for more effective and less toxic therapies for relapsing MCNS.
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Affiliation(s)
| | | | | | | | | | | | - Bert L.P. van den Heuvel
- Department of Pediatric Nephrology
- Laboratory of Pediatrics and Neurology
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Jack F.M. Wetzels
- Department of Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; and
| | - Elena N. Levtchenko
- Department of Pediatric Nephrology
- Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
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Devuyst O, Meij I, Jeunemaitre X, Ronco P, Antignac C, Christensen EI, Knoers NV, Levtchenko EN, Deen PM, Müller D, Wagner CA, Rampoldi L, van't Hoff WG. EUNEFRON, the European Network for the Study of Orphan Nephropathies. Nephrol Dial Transplant 2009; 24:2011-5. [PMID: 19264741 DOI: 10.1093/ndt/gfp095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Besouw MTP, Kremer JAM, Janssen MCH, Levtchenko EN. Fertility status in male cystinosis patients treated with cysteamine. Fertil Steril 2009; 93:1880-3. [PMID: 19217094 DOI: 10.1016/j.fertnstert.2008.12.113] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 12/27/2008] [Accepted: 12/29/2008] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To analyze the fertility status in adult, male cystinosis patients treated with cysteamine. Cystinosis is an autosomal recessive disease leading to intralysosomal cystine accumulation. Worldwide, a few female cystinosis patients have given birth. However, no male cystinosis patients are known to have induced pregnancy. Adequate cysteamine treatment might improve male fertility. PATIENT(S) Seven male cystinosis patients (19-43 years) were submitted. INTERVENTION(S) Glomerular filtration rate was estimated using the Cockcroft formula. Serum LH, FSH, testosterone, and inhibin B were determined. Semen analysis was performed in five patients. Testicular biopsy was performed in one patient. RESULTS Glomerular filtration rate ranged between 10 and 110 (normal >90) mL/min/1.73 m(2), LH and FSH levels ranged between 7.4 and 235.0 (normal 1.4-8.5) E/L and 6.8-298.0 (normal 1.5-11) E/L, respectively. Plasma testosterone level ranged between 8.7 and 31.3 (normal 11-45) nmol/L; plasma inhibin B level ranged between 10 and 210 (normal 150-400) ng/L. All of the collected sperm samples showed azoospermia. The testicular biopsy showed a Johnson score of 8 to 9. CONCLUSION(S) We demonstrate azoospermia in male cystinosis patients, even if adequately treated with cysteamine starting from an early age. The finding of spermatogenesis in the testis biopsy of one patient may provide opportunities to male cystinosis patients to produce their own offspring by in vitro fertilization after testicular sperm extraction.
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Affiliation(s)
- Martine T P Besouw
- Department of Pediatrics/Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
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Wilmer MJ, van den Heuvel LP, Rodenburg RJ, Vogel RO, Nijtmans LG, Monnens LA, Levtchenko EN. Mitochondrial complex V expression and activity in cystinotic fibroblasts. Pediatr Res 2008; 64:495-7. [PMID: 18596576 DOI: 10.1203/pdr.0b013e318183fd67] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Alterations in ATP metabolism have been proposed to be involved in the pathogenesis of cystinosis, the most common form of inherited Fanconi syndrome. A recent study showed normal activity of respiratory chain complexes I-IV with decreased ATP levels in cystinotic fibroblasts. Here, we show normal complex V expression and activity in mitochondria of cystinotic fibroblasts. This indicates that alterations in mitochondrial oxidative phosphorylation enzymes are not responsible for ATP decrease in cystinotic fibroblasts.
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Affiliation(s)
- Martijn J Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, 6500 HB, The Netherlands.
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Abstract
Gitelman syndrome (GS), also referred to as familial hypokalemia-hypomagnesemia, is characterized by hypokalemic metabolic alkalosis in combination with significant hypomagnesemia and low urinary calcium excretion. The prevalence is estimated at approximately 1:40,000 and accordingly, the prevalence of heterozygotes is approximately 1% in Caucasian populations, making it one of the most frequent inherited renal tubular disorders. In the majority of cases, symptoms do not appear before the age of six years and the disease is usually diagnosed during adolescence or adulthood. Transient periods of muscle weakness and tetany, sometimes accompanied by abdominal pain, vomiting and fever are often seen in GS patients. Paresthesias, especially in the face, frequently occur. Remarkably, some patients are completely asymptomatic except for the appearance at adult age of chondrocalcinosis that causes swelling, local heat, and tenderness over the affected joints. Blood pressure is lower than that in the general population. Sudden cardiac arrest has been reported occasionally. In general, growth is normal but can be delayed in those GS patients with severe hypokalemia and hypomagnesemia. GS is transmitted as an autosomal recessive trait. Mutations in the solute carrier family12, member 3 gene, SLC12A3, which encodes the thiazide-sensitive NaCl cotransporter (NCC), are found in the majority of GS patients. At present, more than 140 different NCC mutations throughout the whole protein have been identified. In a small minority of GS patients, mutations in the CLCNKB gene, encoding the chloride channel ClC-Kb have been identified. Diagnosis is based on the clinical symptoms and biochemical abnormalities (hypokalemia, metabolic alkalosis, hypomagnesemia and hypocalciuria). Bartter syndrome (especially type III) is the most important genetic disorder to consider in the differential diagnosis of GS. Genetic counseling is important. Antenatal diagnosis for GS is technically feasible but not advised because of the good prognosis in the majority of patients. Most asymptomatic patients with GS remain untreated and undergo ambulatory monitoring, once a year, generally by nephrologists. Lifelong supplementation of magnesium (magnesium-oxide and magnesium-sulfate) is recommended. Cardiac work-up should be offered to screen for risk factors of cardiac arrhythmias. All GS patients are encouraged to maintain a high-sodium and high potassium diet. In general, the long-term prognosis of GS is excellent.
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Affiliation(s)
- Nine V A M Knoers
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Wilmer MJ, Christensen EI, van den Heuvel LP, Monnens LA, Levtchenko EN. Urinary protein excretion pattern and renal expression of megalin and cubilin in nephropathic cystinosis. Am J Kidney Dis 2008; 51:893-903. [PMID: 18455850 DOI: 10.1053/j.ajkd.2008.03.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 03/03/2008] [Indexed: 11/11/2022]
Abstract
BACKGROUND Nephropathic cystinosis is the most common cause of inherited renal Fanconi syndrome, caused by mutations in lysosomal cystine carrier cystinosin that result in lysosomal cystine accumulation throughout the body. How defects in cystinosin cause proximal tubular dysfunction is not known. We hypothesized that cystine accumulation could cause disturbed proximal tubular endocytosis by megalin and cubilin. STUDY DESIGN Megalin, cubilin, and their ligands were studied in kidney tissue by means of immunohistochemistry. Urinary protein excretion pattern was evaluated. SETTING & PARTICIPANTS Kidney tissue from a patient with cystinosis was compared with minimal change nephrotic syndrome tissue, end-stage renal disease tissue, and control renal tissue. Urine from 7 patients with cystinosis was compared with 6 control samples. RESULTS Expression of megalin, cubilin, and ligands (transferrin, albumin, vitamin D-binding protein, alpha(1)-microglobulin, retinol-binding protein, and beta(2)-microglobulin) in convoluted proximal tubules of cystinotic kidney was similar to that in other kidney specimens. In straight tubules, low-molecular-weight proteins were present in only cystinotic kidney samples. Next to low-molecular-weight proteins and albumin, urinary excretion of immunoglobulin G was increased in patients with cystinosis with Fanconi syndrome compared with controls. This was already observed at an early age, suggesting enhanced glomerular permeability in patients with cystinosis. LIMITATIONS This study is essentially observational, and immunohistochemical data are based on 1 cystinotic kidney. CONCLUSION Our findings indicate that low-molecular-weight proteinuria in patients with cystinosis is not caused by decreased megalin and cubilin expression, and glomerular damage might already be present at early stages of the disease.
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Affiliation(s)
- Martijn J Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Taranta A, Petrini S, Palma A, Mannucci L, Wilmer MJ, De Luca V, Diomedi-Camassei F, Corallini S, Bellomo F, van den Heuvel LP, Levtchenko EN, Emma F. Identification and subcellular localization of a new cystinosin isoform. Am J Physiol Renal Physiol 2008; 294:F1101-8. [DOI: 10.1152/ajprenal.00413.2007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Nephropathic cystinosis is a lysosomal disorder caused by functional defects of cystinosin, which mediates cystine efflux into the cytosol. The protein sequence contains at least two signals that target the protein to the lysosomal compartment, one of which is located at the carboxy terminal tail (GYDQL). We have isolated from a human kidney cDNA library a cystinosin isoform, which is generated by an alternative splicing of exon 12 that removes the GYDQL motif. Based on its last three amino acids, we have termed this protein cystinosin-LKG. Contrary to the lysosomal cystinosin isoform, expression experiments performed by transient transfection of green fluorescent protein fusion plasmids in HK2 cells showed that cystinosin-LKG is expressed in the plasma membrane, in lysosomes, and in other cytosolic structures. This subcellular localization of the protein was confirmed by transmission electron microscopy. In addition, immunogold labeling was observed in the endoplasmic reticulum and in the Golgi apparatus. Expression of the protein in renal tubular structures was also directly demonstrated by immunostaining of normal human kidney sections. The plasma membrane localization of cystinosin-LKG was directly tested by [35S]cystine flux experiments in COS-1 cells. In the presence of a proton gradient, a marked enhancement of intracellular cystine transport was observed in cells overexpressing this isoform. These data indicate that the expression of the gene products encoded by the CTNS gene is not restricted to the lysosomal compartment. These finding may help elucidate the mechanisms of cell dysfunction in this disorder.
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Affiliation(s)
- Martijn J Wilmer
- Laboratory of Pediatrics and Neurology (656), Radboud University Nijmegen Medical Centre, P.O. 9101, 6500 HB, Nijmegen, The Netherlands.
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Wamelink MMC, Struys EA, Jansen EEW, Levtchenko EN, Zijlstra FSM, Engelke U, Blom HJ, Jakobs C, Wevers RA. Sedoheptulokinase deficiency due to a 57-kb deletion in cystinosis patients causes urinary accumulation of sedoheptulose: elucidation of the CARKL gene. Hum Mutat 2008; 29:532-6. [PMID: 18186520 DOI: 10.1002/humu.20685] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The most common mutation in the nephropathic cystinosis (CTNS) gene is a homozygous 57-kb deletion that also includes an adjacent gene carbohydrate kinase-like (CARKL). The latter gene encodes a protein that is predicted to function as a carbohydrate kinase. Cystinosis patients with the common 57-kb deletion had strongly elevated urinary concentrations of sedoheptulose (28-451 mmol/mol creatinine; controls and other cystinosis patients <9) and erythritol (234-1110 mmol/mol creatinine; controls and other cystinosis patients <148). Enzyme studies performed on fibroblast homogenates derived from patients carrying the 57-kb deletion revealed 80% reduction in their sedoheptulose phosphorylating activity compared to cystinosis patients with other mutations and controls. This indicates that the CARKL-encoded protein, sedoheptulokinase (SHK), is responsible for the reaction: sedoheptulose + ATP --> sedoheptulose-7-phosphate + ADP and that deletion of CARKL causes urinary accumulation of sedoheptulose and erythritol.
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Affiliation(s)
- Mirjam M C Wamelink
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center, Amsterdam, The Netherlands.
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Besouw MTP, Levtchenko EN, Willemsen MAAP, Noordam K. Growth hormone producing prolactinoma in juvenile cystinosis: a simple coincidence? Pediatr Nephrol 2008; 23:307-10. [PMID: 17638022 PMCID: PMC2668588 DOI: 10.1007/s00467-007-0543-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 05/30/2007] [Accepted: 05/31/2007] [Indexed: 12/01/2022]
Abstract
Juvenile cystinosis was diagnosed in a patient who presented with severe headache attacks and photophobia. Treatment with oral cysteamine and topical cysteamine eye drops was started. One-and-a-half years later, he developed unilateral gynecomastia and elevated prolactin and growth hormone levels. A pituitary macroprolactinoma was discovered and successfully treated with the dopamine agonist cabergoline. Increased serum growth hormone levels were attributed to enhanced growth hormone production by the prolactinoma and somatostatin inhibition by cysteamine. Although the occurrence of prolactinoma in this patient could be a simple coincidence, it might also be a rare yet unrecognised complication of cystinosis.
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Affiliation(s)
- Martine T. P. Besouw
- Department of Pediatric Nephrology, University Medical Centre St Radboud, Nijmegen, The Netherlands
| | - Elena N. Levtchenko
- Department of Pediatric Nephrology, University Medical Centre St Radboud, Nijmegen, The Netherlands
- Geert Grooteplein 10, P.O. 9101, 6500 HB Nijmegen, The Netherlands
| | | | - Kees Noordam
- Department of Metabolic and Endocrine Disorders, University Medical Centre St Radboud, Nijmegen, The Netherlands
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Dorresteijn EM, Kist-van Holthe JE, Levtchenko EN, Nauta J, Hop WCJ, van der Heijden AJ. Mycophenolate mofetil versus cyclosporine for remission maintenance in nephrotic syndrome. Pediatr Nephrol 2008; 23:2013-20. [PMID: 18622632 PMCID: PMC7462920 DOI: 10.1007/s00467-008-0899-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 05/20/2008] [Accepted: 05/20/2008] [Indexed: 11/25/2022]
Abstract
We performed a multi-centre randomized controlled trial to compare the efficacy of mycophenolate mofetil (MMF) to that of cyclosporine A (CsA) in treating children with frequently relapsing nephrotic syndrome and biopsy-proven minimal change disease. Of the 31 randomized initially selected patients, seven were excluded. The remaining 24 children received either MMF 1200 mg/m(2) per day (n = 12) or CsA 4-5 mg/kg per day (n = 12) during a 12-month period. Of the 12 patients in the MMF group, two discontinued the study medication. Evaluation of the changes from the baseline glomerular filtration rate showed an overall significant difference in favour of MMF over the treatment period (p = 0.03). Seven of the 12 patients in the MMF group and 11 of the 12 patients in the CsA group remained in complete remission during the entire study period. Relapse rate in the MMF group was 0.83/year compared to 0.08/year in the CsA group (p = 0.08). None of the patients reported diarrhea. Pharmacokinetic profiles of mycophenolic acid were performed in seven patients. The patient with the lowest area under the curve had three relapses within 6 months. In children with frequently relapsing minimal change nephrotic syndrome, MMF has a favourable side effect profile compared to CsA; however, there is a tendency towards a higher relapse risk in patients treated with MMF.
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Affiliation(s)
- Eiske M. Dorresteijn
- Department of Pediatric Nephrology, Erasmus Medical Center/Sophia Children’s Hospital, Dr Molewaterplein 60, 3015 GJ Rotterdam, the Netherlands
| | | | - Elena N. Levtchenko
- Department of Pediatric Nephrology, University Hospital Leuven, Leuven, Belgium
| | - Jeroen Nauta
- Department of Pediatric Nephrology, Erasmus Medical Center/Sophia Children’s Hospital, Dr Molewaterplein 60, 3015 GJ Rotterdam, the Netherlands
| | - Wim C. J. Hop
- Department of Epidemiology and Biostatistics, Erasmus Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Albert J. van der Heijden
- Department of Pediatric Nephrology, Erasmus Medical Center/Sophia Children’s Hospital, Dr Molewaterplein 60, 3015 GJ Rotterdam, the Netherlands
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46
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Huls M, Kramers C, Levtchenko EN, Wilmer MJG, Dijkman HBPM, Kluijtmans LAJ, van der Hoorn JWA, Russel FGM, Masereeuw R. P-glycoprotein-deficient mice have proximal tubule dysfunction but are protected against ischemic renal injury. Kidney Int 2007; 72:1233-41. [PMID: 17851469 DOI: 10.1038/sj.ki.5002522] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The multidrug resistance gene 1 product, P-glycoprotein (P-gp), is expressed in several excretory organs, including the apical membrane of proximal tubules. After inducing acute renal failure, P-gp expression is upregulated and this might be a protective function by pumping out toxicants and harmful products of oxidative stress. We characterized renal function of P-gp knockout mice and studied its consequences in renal ischemic damage. Compared with wild-type mice, knockout mice have a lower glomerular filtration rate and renal plasma flow. An augmented urinary excretion of sodium, numerous amino acids, calcium, glucose, and low molecular weight proteins was observed along with an increased diuresis. A higher lithium plasma clearance in the knockout mice suggested proximal tubular dysfunction. Electron microscopy showed mitochondrial abnormalities in proximal tubular cells that could account for decreased adenosine triphosphate levels in the cortex. After inducing ischemia, wild-type mice showed a decrease in creatinine clearance and severe proximal tubular necrosis. In contrast, knockout mice had no signs of tubular damage. Our data indicate that P-gp knockout mice have impaired renal function but are protected against ischemic renal injury.
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Affiliation(s)
- M Huls
- Department of Pharmacology and Toxicology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Levtchenko EN, Monnens LAH, Bökenkamp A, Knoers NV. [From gene to disease; Dent's disease caused by abnormalities in the CLCN5 and OCRL1 genes]. Ned Tijdschr Geneeskd 2007; 151:2377-2380. [PMID: 18019214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Dent's disease is an X-linked disorder, characterized by generalized proximal tubular dysfunction, nephrolithiasis, nephrocalcinosis and the development ofend-stage renal disease, generally occurring after the age of thirty. In the majority of cases, the disease is caused by mutations in the CLCN5-gene. The pathogenesis of the disease has not yet been clarified. Defective recycling of multi-ligand proximal tubular receptors megalin and cubilin is considered responsible for the defective reabsorption of low molecular weight proteins, albumin, hormones and vitamins. Treatment with thiazide diuretics to diminish the hypercalciuria in combination with citrate supplements might prevent renal stone formation and deterioration of renal function. In the laboratory ofDNA diagnostics in the Radboud University Nijmegen Medical Centre, the molecular analysis of the CLCN5-gene in patients suspected with this disease is performed.
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Affiliation(s)
- E N Levtchenko
- Universitair Medisch Centrum St Radboud, Postbus 9101, 6500 HB Nijmegen.
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Löwik MM, Groenen PJTA, Pronk I, Lilien MR, Goldschmeding R, Dijkman HB, Levtchenko EN, Monnens LA, van den Heuvel LP. Focal segmental glomerulosclerosis in a patient homozygous for a CD2AP mutation. Kidney Int 2007; 72:1198-203. [PMID: 17713465 DOI: 10.1038/sj.ki.5002469] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histologic diagnosis in several kidney diseases characterized by proteinuria and a severe decrease in kidney function. Mutations in several genes were found in patients with primary FSGS, one of which is a CD2-associated protein CD2AP (originally referred to as CMS). This gene encodes an adaptor protein that plays a role in endocytosis, cell motility, and cell survival. Mice deficient in Cd2ap (the mouse homolog) die due to kidney failure, while heterozygous mice develop lesions similar to those of FSGS patients. In the kidney, CD2AP regulates the actin cytoskeleton. The only previously described patient with CD2AP mutation had a severely truncated protein. In this study, we describe a patient with a novel mutation resulting in a premature stop codon yielding a protein truncated by only 4%. This shortened CD2AP protein displays a significantly decreased F-actin binding efficiency in vitro with no expression of the mutated allele in the patient's lymphocytes. Heterozygous expression of the CD2AP mutation in both parents did not lead to any kidney pathology, as both have normal glomerular filtration rates and no proteinuria.
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Affiliation(s)
- M M Löwik
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Wilmer MJ, Willems PH, Verkaart S, Visch HJ, de Graaf-Hess A, Blom HJ, Monnens LA, van den Heuvel LP, Levtchenko EN. Cystine dimethylester model of cystinosis: still reliable? Pediatr Res 2007; 62:151-5. [PMID: 17597653 DOI: 10.1203/pdr.0b013e31809fd9a7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The ability of cystine dimethylester (CDME) to load lysosomes with cystine has been used to establish the basic defect in cystinosis: defective cystine exodus from lysosomes. Using CDME loading, it has been postulated that cystine accumulation in cystinosis affects mitochondrial ATP production, resulting in defective renal tubular reabsorption. Recent studies in cystinotic fibroblasts, however, show normal adenosine triphosphate (ATP) generation capacity. To investigate the effect of CDME in more detail, mitochondrial ATP generation, reactive oxygen species production, and viability are compared in fibroblasts loaded with CDME with those of cystinotic cells with a defective cystine transporter. Intracellular cystine levels were comparable in fibroblasts loaded with CDME (1 mM, 30 min) and cystinotic fibroblasts. Intracellular ATP levels and mitochondrial ATP production were decreased in fibroblasts loaded with CDME, but normal in cystinotic fibroblasts. Superoxide production was increased with 300% after CDME loading, whereas no changes were observed in cystinotic fibroblasts. Exposure to CDME led to cell death in a time- and concentration-dependent manner. Our data demonstrate that CDME has a toxic effect on mitochondrial ATP production and cell viability. These effects are not observed in cystinotic cells, indicating that a more appropriate model is required for studying the pathogenesis of cystinosis.
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Affiliation(s)
- Martijn J Wilmer
- Laboratory of Pediatrics and Neurology, Radboud University Nijmegen Medical Centre, 6500 HB, Nijmegen, The Netherlands.
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Kyrieleis HAC, Levtchenko EN, Wetzels JFM. Long-Term Outcome After Cyclophosphamide Treatment in Children With Steroid-Dependent and Frequently Relapsing Minimal Change Nephrotic Syndrome. Am J Kidney Dis 2007; 49:592-7. [PMID: 17472840 DOI: 10.1053/j.ajkd.2007.02.270] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 02/22/2007] [Indexed: 11/11/2022]
Abstract
BACKGROUND Seventy percent of children with minimal change nephrotic syndrome (MCNS) have a steroid-dependent or frequent relapsing course of the disease, and most are treated with cyclophosphamide. We describe the clinical course of children with biopsy-proven MCNS treated with cyclophosphamide for steroid-dependent or frequently relapsing nephrotic syndrome at our institution from 1971 to 2003. METHODS From our pathology registry, we identified 93 patients with biopsy-proven MCNS who received cyclophosphamide therapy. Follow-up information from medical records and mailed questionnaires could be obtained for 80 patients (86%). RESULTS Only 35% of patients experienced no relapse after cyclophosphamide therapy. Twenty-one patients subsequently were treated with cyclosporine, with only 3 (14%) achieving persistent remission. At the end of follow-up, 23 patients (25%) still experienced relapse, and all except 3 patients required continuous immunosuppressive therapy. However, the cumulative incidence of persistent complete remission (>2 years without medication) increased over time (35% at 2 years, 52% at 6 years, and 71% at 15 years after the start of cyclophosphamide therapy), and no patient developed kidney failure. By means of univariate analysis, age younger than 3 years at onset predicted a lower likelihood of attaining remission (P < 0.05). CONCLUSION More than a quarter of a selected group of cyclophosphamide-treated patients with steroid-dependent or frequently relapsing MCNS were not in remission after puberty and required prolonged immunosuppressive treatment. There is an urgent need for more effective treatment modalities resulting in persistent remission in these patients.
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Affiliation(s)
- Henriette A C Kyrieleis
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
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