RESUMO
One of the hallmarks of chronic kidney disease (CKD) is the development of vascular calcification. Inorganic pyrophosphate is a potent inhibitor of calcification, and previous studies have reported low plasma pyrophosphate levels in hemodialysis patients. A long-term mouse model of CKD-accelerated vascular calcification was developed to study pyrophosphate metabolism and to test whether oral pyrophosphate supplementation attenuates the propensity for arterial calcification. CKD was induced by repeated injections of aristolochic acid in wild-type and Abcc6-/- mice, which tend to develop vascular calcifications. CKD accelerated the development of vascular calcifications in Abcc6-/- mice, in the aorta and small renal arteries, and decreased circulating pyrophosphate levels. Oral pyrophosphate supplementation for 6 months attenuated CKD-induced vascular calcification in this model. These results show that oral pyrophosphate may be of interest in preventing vascular calcification in patients with CKD. KEY MESSAGES: Chronic kidney disease accelerates the development of vascular calcification in pyrophosphate-deficient mice. Oral pyrophosphate supplementation for 6 months attenuates chronic kidney disease-induced vascular calcification in a mouse model. Oral pyrophosphate may be of interest in preventing vascular calcification in patients with chronic kidney disease.
Assuntos
Glioxilatos , Preparações para Cabelo , Cabelo , Nefropatias , Rim , Humanos , Glioxilatos/efeitos adversos , Glioxilatos/farmacologia , Cabelo/efeitos dos fármacos , Rim/efeitos dos fármacos , Rim/lesões , Preparações para Cabelo/efeitos adversos , Preparações para Cabelo/análise , Preparações para Cabelo/farmacologia , Nefropatias/induzido quimicamenteRESUMO
Calcific uremic arteriolopathy (CUA) is a severely morbid disease, affecting mostly dialyzed end-stage renal disease (ESRD) patients, associated with calcium deposits in the skin. Calcifications have been identified in ESRD patients without CUA, indicating that their presence is not specific to the disease. The objective of this retrospective multicenter study was to compare elastic fiber structure and skin calcifications in ESRD patients with CUA to those without CUA using innovative structural techniques. Fourteen ESRD patients with CUA were compared to 12 ESRD patients without CUA. Analyses of elastic fiber structure and skin calcifications using multiphoton microscopy followed by machine-learning analysis and field-emission scanning electron microscopy coupled with energy dispersive X-ray were performed. Elastic fibers specifically appeared fragmented in CUA. Quantitative analyses of multiphoton images showed that they were significantly straighter in ESRD patients with CUA than without CUA. Interstitial and vascular calcifications were observed in both groups of ESRD patients, but vascular calcifications specifically appeared massive and circumferential in CUA. Unlike interstitial calcifications, massive circumferential vascular calcifications and elastic fibers straightening appeared specific to CUA. The origins of such specific elastic fiber's alteration are still to be explored and may involve relationships with ischemic vascular or inflammatory processes.
Assuntos
Calciofilaxia , Falência Renal Crônica , Calcificação Vascular , Humanos , Tecido Elástico , Falência Renal Crônica/complicações , Margens de Excisão , Microscopia Eletrônica de VarreduraRESUMO
Arterial calcification is a common feature of pseudoxanthoma elasticum (PXE), a disease characterized by ABCC6 mutations, inducing a deficiency in pyrophosphate, a key inhibitor of calcium phosphate crystallization in arteries. METHODS: we analyzed whether long-term exposure of Abcc6-/- mice (a murine model of PXE) to a mild vitamin D supplementation, with or without calcium, would impact the development of vascular calcification. Eight groups of mice (including Abcc6-/- and wild-type) received vitamin D supplementation every 2 weeks, a calcium-enriched diet alone (calcium in drinking water), both vitamin D supplementation and calcium-enriched diet, or a standard diet (controls) for 6 months. Aorta and kidney artery calcification was assessed by 3D-micro-computed tomography, Optical PhotoThermal IR (OPTIR) spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and Yasue staining. RESULTS: at 6 months, although vitamin D and/or calcium did not significantly increase serum calcium levels, vitamin D and calcium supplementation significantly worsened aorta and renal artery calcification in Abcc6-/- mice. CONCLUSIONS: vitamin D and/or calcium supplementation accelerate vascular calcification in a murine model of PXE. These results sound a warning regarding the use of these supplementations in PXE patients and, to a larger extent, patients with low systemic pyrophosphate levels.
Assuntos
Calcificação Fisiológica/efeitos dos fármacos , Cálcio da Dieta/farmacologia , Cálcio/farmacologia , Pseudoxantoma Elástico/tratamento farmacológico , Calcificação Vascular/tratamento farmacológico , Vitamina D/farmacologia , Animais , Artérias/efeitos dos fármacos , Artérias/metabolismo , Suplementos Nutricionais , Modelos Animais de Doenças , Feminino , Camundongos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Pseudoxantoma Elástico/metabolismo , Calcificação Vascular/metabolismoRESUMO
Calpains, intracellular proteases specifically inhibited by calpastatin, play a major role in neoangiogenesis involved in tumor invasiveness and metastasis. They are partly exteriorized via the ATP-binding cassette transporter A1(ABCA1) transporter, but the importance of this process in tumor growth is still unknown. The aim of our study was to investigate the role of extracellular calpains in a model of melanoma by blocking their extracellular activity or exteriorization. In the first approach, a B16-F10 model of melanoma was developed in transgenic mice expressing high extracellular levels of calpastatin. In these mice, tumor growth was inhibited by â¼ 3-fold compared with wild-type animals. In vitro cytotoxicity assays and in vivo tumor studies have demonstrated that this protection was associated with a defect in tumor neoangiogenesis. Similarly, in wild-type animals given probenecid to blunt ABCA1 activity, melanoma tumor growth was inhibited by â¼ 3-fold. Again, this response was associated with a defect in neoangiogenesis. In vitro studies confirmed that probenecid limited endothelial cell migration and capillary formation from vascular explants. The observed reduction in fibronectin cleavage under these conditions is potentially involved in the response. Collectively, these studies demonstrate that probenecid, by blunting ABCA1 activity and thereby calpain exteriorization, limits melanoma tumor neoangiogenesis and invasiveness.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/antagonistas & inibidores , Calpaína/metabolismo , Melanoma Experimental/tratamento farmacológico , Neovascularização Patológica/tratamento farmacológico , Probenecid/farmacologia , Neoplasias Cutâneas/tratamento farmacológico , Transportador 1 de Cassete de Ligação de ATP/genética , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Linhagem Celular Tumoral/transplante , Proliferação de Células/efeitos dos fármacos , Humanos , Masculino , Melanoma Experimental/irrigação sanguínea , Melanoma Experimental/patologia , Camundongos , Camundongos Transgênicos , Neovascularização Patológica/patologia , Probenecid/uso terapêutico , Neoplasias Cutâneas/irrigação sanguínea , Neoplasias Cutâneas/patologiaRESUMO
Most kidney stones are made of calcium oxalate crystals. Randall's plaque, an apatite deposit at the tip of the renal papilla, is considered to at the origin of these stones. Hypercalciuria may promote Randall's plaque formation and growth. We analyzed whether long-term exposure of Abcc6-/- mice (a murine model of Randall's plaque) to vitamin D supplementation, with or without a calcium-rich diet, would accelerate the formation of Randall's plaque. Eight groups of mice (including Abcc6-/- and wild type) received vitamin D alone (100,000 UI/kg every 2 weeks), a calcium-enriched diet alone (calcium gluconate 2 g/L in drinking water), both vitamin D supplementation and a calcium-rich diet, or a standard diet (controls) for 6 months. Kidney calcifications were assessed by 3-dimensional microcomputed tomography, µ-Fourier transform infrared spectroscopy, field emission-scanning electron microscopy, transmission electron microscopy, and Yasue staining. At 6 months, Abcc6-/- mice exposed to vitamin D and calcium supplementation developed massive Randall's plaque when compared with control Abcc6-/- mice (P < 0.01). Wild-type animals did not develop significant calcifications when exposed to vitamin D. Combined administration of vitamin D and calcium significantly accelerates Randall's plaque formation in a murine model. This original model raises concerns about the cumulative risk of vitamin D supplementation and calcium intakes in Randall's plaque formation.
Assuntos
Cálcio da Dieta/efeitos adversos , Suplementos Nutricionais/efeitos adversos , Cálculos Renais/induzido quimicamente , Medula Renal/metabolismo , Vitamina D/efeitos adversos , Animais , Calcinose/induzido quimicamente , Calcinose/metabolismo , Calcinose/patologia , Cálcio da Dieta/administração & dosagem , Modelos Animais de Doenças , Progressão da Doença , Feminino , Cálculos Renais/metabolismo , Cálculos Renais/patologia , Medula Renal/patologia , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Fatores de Tempo , Vitamina D/administração & dosagemRESUMO
Increased urinary oxalate excretion (hyperoxaluria) promotes the formation of calcium oxalate crystals. Monogenic diseases due to hepatic enzymes deficiency result in chronic hyperoxaluria, promoting end-stage renal disease in children and young adults. Ethylene glycol poisoning also results in hyperoxaluria promoting acute renal failure and frequently death. Stiripentol is an antiepileptic drug used to treat children affected by Dravet syndrome, possibly by inhibiting neuronal lactate dehydrogenase 5 isoenzyme. As this isoenzyme is also the last step of hepatic oxalate production, we hypothesized that Stiripentol would potentially reduce hepatic oxalate production and urine oxalate excretion. In vitro, Stiripentol decreased in a dose-dependent manner the synthesis of oxalate by hepatocytes. In vivo, Stiripentol oral administration reduced significantly urine oxalate excretion in rats. Stiripentol protected kidneys against calcium oxalate crystal deposits in acute ethylene glycol intoxication and chronic calcium oxalate nephropathy models. In both models, Stiripentol improved significantly renal function. Patients affected by Dravet syndrome and treated with Stiripentol had a lower urine oxalate excretion than control patients. A young girl affected by severe type I hyperoxaluria received Stiripentol for several weeks: urine oxalate excretion decreased by two-thirds. Stiripentol is a promising potential therapy against genetic hyperoxaluria and ethylene glycol poisoning.
Assuntos
Dioxolanos/farmacologia , Etilenoglicol/intoxicação , Hiperoxalúria Primária/prevenção & controle , Nefrolitíase/prevenção & controle , Animais , Oxalato de Cálcio/metabolismo , Epilepsias Mioclônicas/tratamento farmacológico , Epilepsias Mioclônicas/metabolismo , Epilepsias Mioclônicas/patologia , Feminino , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Hiperoxalúria Primária/metabolismo , Hiperoxalúria Primária/patologia , Rim/metabolismo , Rim/patologia , Masculino , Nefrolitíase/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: Pseudoxanthoma elasticum (PXE) is a genetic disease caused by mutations in the ABCC6 gene that result in low pyrophosphate levels and subsequent progressive soft tissue calcifications. PXE mainly affects the skin, retina, and arteries. However, many patients with PXE experience kidney stones. We determined the prevalence of this pathology in patients with PXE and examined the possible underlying mechanisms in murine models. METHODS: We conducted a retrospective study in a large cohort of patients with PXE and analyzed urine samples and kidneys from Abcc6-/- mice at various ages. We used Yasue staining, scanning electron microscopy, electron microscopy coupled to electron energy loss spectroscopy, and Fourier transform infrared microspectroscopy to characterize kidney calcifications. RESULTS: Among 113 patients with PXE, 45 (40%) had a past medical history of kidney stones. Five of six computed tomography scans performed showed evidence of massive papillary calcifications (Randall plaques). Abcc6-/- mice spontaneously developed kidney interstitial apatite calcifications with aging. These calcifications appeared specifically at the tip of the papilla and formed Randall plaques similar to those observed in human kidneys. Compared with controls, Abcc6-/- mice had low urinary excretion of pyrophosphate. CONCLUSIONS: The frequency of kidney stones and probably, Randall plaque is extremely high in patients with PXE, and Abcc6-/- mice provide a new and useful model in which to study Randall plaque formation. Our findings also suggest that pyrophosphate administration should be evaluated for the prevention of Randall plaque and kidney stones.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Cálculos Renais/etiologia , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Pseudoxantoma Elástico/genética , Pseudoxantoma Elástico/patologia , Animais , Biópsia por Agulha , Calcinose/genética , Calcinose/patologia , Estudos de Coortes , Modelos Animais de Doenças , Feminino , Humanos , Imuno-Histoquímica , Incidência , Cálculos Renais/epidemiologia , Cálculos Renais/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Prognóstico , Pseudoxantoma Elástico/complicações , Pseudoxantoma Elástico/diagnóstico por imagem , Estudos Retrospectivos , Medição de Risco , Tomografia Computadorizada por Raios X/métodos , UrináliseRESUMO
Various disorders including pseudoxanthoma elasticum (PXE) and generalized arterial calcification of infancy (GACI), which are caused by inactivating mutations in ABCC6 and ENPP1, respectively, present with extensive tissue calcification due to reduced plasma pyrophosphate (PPi). However, it has always been assumed that the bioavailability of orally administered PPi is negligible. Here, we demonstrate increased PPi concentration in the circulation of humans after oral PPi administration. Furthermore, in mouse models of PXE and GACI, oral PPi provided via drinking water attenuated their ectopic calcification phenotype. Noticeably, provision of drinking water with 0.3 mM PPi to mice heterozygous for inactivating mutations in Enpp1 during pregnancy robustly inhibited ectopic calcification in their Enpp1-/- offspring. Our work shows that orally administered PPi is readily absorbed in humans and mice and inhibits connective tissue calcification in mouse models of PXE and GACI PPi, which is recognized as safe by the FDA, therefore not only has great potential as an effective and extremely low-cost treatment for these currently intractable genetic disorders, but also in other conditions involving connective tissue calcification.