A hiperfosfatemia está relacionada com o hiperparatireoidismo secundário renal (HPTSR) e com a progressão da doença renal crônica (DRC). A retenção de fósforo estimula a síntese do fator de crescimento de fibroblastos 23 (FGF-23), o qual promove fosfatúria, com o objetivo de evitar o aparecimento de hiperfosfatemia. Atualmente, o tratamento disponível para DRC é de manutenção e, portanto, novas estratégias para evitar a progressão da DRC seriam de grande relevância. Recentemente têm sido demonstrado o papel da célula-tronco mesenquimal (CTM) em minimizar os mecanismos inflamatórios e imunológicos envolvidos na progressão da DRC. Portanto, o estudo teve como hipótese de que a CTM possa evitar ou controlar a progressão para o HPTSR, investigada por meio da avaliação de biomarcadores do metabolismo de fósforo, ou seja, as concentrações sérica de fósforo (sP), FGF-23, cálcio total e cálcio ionizado, bem como a excreção fracionada de fósforo urinária (uFEP) em cães com DRC nos estágios 2 (Grupo A) e 3 (Grupo B), submetidos ou não a terapia com CTM, bem como investigar se os valores elevados de FGF-23 estariam relacionados com o menor tempo de sobrevida. Trata-se de um estudo prospectivo, longitudinal, duplo-cego e randomizado em que foram avaliados 22 cães com DRC, tratados com solução fisiológica (SF) ou CTM, avaliados a cada 30 a 45 dias em 12 momentos (T0 a T12). No Grupo A (n= 9; SF: n= 6, CTM: n= 3) todos os cães eram normofosfatêmicos no momento inicial do acompanhamento (T0) e foi observado níveis elevados de FGF-23 em 33,3% dos cães (3 de 9), assim como o aumento de uFEP foi detectado em 33,3% dos casos (3 de 9). A média ± EPM dos valores de FGF-23 sérico do Grupo A foi de 481,5 ± 75,23pg/mL. Já no Grupo B (n = 13; SF: n = 6, CTM: n = 7), todos os cães apresentaram altas concentrações séricas de FGF-23 desde T0 (média ± EPM de 12744 ± 6879pg/mL), sendo que 53,8% dos cães eram normofosfatêmicos. A média ± EPM de fósforo sérico em T0, T6 e T12 ou momento do óbito no Grupo A e B foi de 3,74 ± 0,13mg/dL e 6,40 ± 0,54mg/dL. Ao longo do curso da doença, o desenvolvimento de hiperfosfatemia foi observada em apenas 11,1% dos cães do Grupo A e em 84,6% dos cães do Grupo B. O Grupo B (SF e CTM) apresentou valores mais elevados de FGF-23 do que o Grupo A (SF e CTM), e foi detectada diferença estatística entre os dois grupos. A uFEP nos cães dos Grupos A e B em T0, T6 e T12 ou óbito obteve média ± EPM de 20,93 ± 3,92% e 24,05 ± 2,22%, respectivamente. Além disso, a sobrevida foi menor no Grupo B, a qual estava associada com hiperfosfatemia intensa, altas concentrações de FGF-23 e diminuição da uFEP. Dessa forma, em cães DRC normofosfatêmicos, a presença de aumentos de uFEP e de FGF-23 parece terem atuado como marcador precoce do HPTSR. Em contrapartida, nos estágios tardios da DRC, o aumento de FGF-23 associado a diminuição da uFEP pode indicar mau prognóstico. Em relação à terapia com CTM nos cães com DRC, de acordo com o número de cães avaliados e os resultados obtidos, não foi possível concluir de forma contundente sobre o efeito da terapia com CTM na doença renal crônica de curso natural em cães, entretanto, os resultados obtidos foram relevantes, pois suscitaram questões quanto ao momento ou o estágio da DRC que seria o mais adequado para a indicação da terapia celular para que os efeitos benéficos possam ser obtidos. Assim, ainda se faz necessária a condução de mais pesquisas com um número maior de cães com DRC para avaliar efeito da CTM em evitar o distúrbio no metabolismo mineral, bem como a progressão da DRC em cães / Hyperphosphatemia is associated with renal secondary hyperparathyroidism (SRHP) and chronic kidney disease (CKD) progression. Phosphorus retention stimulates the synthesis of fibroblast growth factor 23 (FGF-23), which promotes phosphaturia in order to avoid the onset of hyperphosphatemia. Conservative treatment of CKD is currently avaliable and new strategies are needed and welcome to avoid the progression of renal injury. Recent studies have shown the role of mesenchymal stem cell (MSC) in minimizing inflammatory and immunological mechanisms known as mediators of CKD progression. Therefore, it was hypothesized that MSCs could avoid or control the progression to SRHP, assessed by serum phosphorus (sP), FGF-23, total and ionized calcium and fractional excretion of phosphorus (uFEP) in CKD dogs in Stages 2 (Group A) and 3 (Group B), also was investigated whether high values of FGF-23 could be associatted with shorter survival time. Prospective, double-blind, randomized and longitudinal study was conducted enrolling 22 dogs with CKD treated with saline solution (SS) or MSC, which were evaluated every 30 to 45 days in 12 moments (T0 to T12). In Group A (n = 9; SF: n = 6, CTM: n = 3) all dogs were normophosphatemic at the beginning of the follow-up (T0) and high levels of FGF-23 were already detected in 33.3% of dogs (3 of 9), as well as increased in uFEP (33.3%; 3 of 9). The mean ± SEM of serum FGF-23 in Group A was 481.50 ± 75.23pg/mL. In Group B (n = 13; SS: n = 6, MSC: n = 7), all dogs showed high concentrations of serum FGF-23 since T0 (mean ± SEM of 12744 ± 6979pg/mL), and normophosphatemia detected in 53.8% of them. The mean ± SEM of serum phosphorus at T0, T6 and T12 or death in Group A and B was 3.74 ± 0.13mg/dL and 6.40 ± 0.54mg/dL. Hyperphosphatemia developed during the follow-up in only 11.1% of the dogs of Group A and 84.6% of the dogs of Group B. Group B (SS and MSC) had higher levels of FGF-23 than Group A (SS and MSC), and difference bewteen those groups detected. The uFEP in dogs of Groups A and B at T0, T6 and T12 or death obtained mean ± SEM of 20.93 ± 3.92% and 24.05 ± 2.22%, respectively. Furthermore, the survival rate was lower in Group B, which was associated with severe hyperphosphatemia, high values of serum FGF-23 and decreased uFEP. Therefore in normophophatemic CKD dogs, the increased in uFEP and high levels of FGF-23 may act as an early marker of SRHP. However, in later stages of CKD, increased levels of serum FGF-23 associated with decreased uFEP and hyperphosphatemia may indicate poor prognosis. Regarding to the MSC therapy in dogs with CKD, the number of dogs involved and also according to the results, it still has not allowed to conclude the effect of therapy with mesenchymal stem cell in spontaneous chronic kidney disease; however, the results obtained raised important questions such as the time or the stage of CKD that could be more suitable for the use of stem cell therapy in order to get its beneficial effects. Therefore, futher studies are needed, including greater number of dogs with CKD and then to evaluate the effect or action of MSC to avoid disturbances in mineral metabolism as well as the progression of CKD in dogs

A hiperfosfatemia está relacionada com o hiperparatireoidismo secundário renal (HPTSR) e com a progressão da doença renal crônica (DRC). A retenção de fósforo estimula a síntese do fator de crescimento de fibroblastos 23 (FGF-23), o qual promove fosfatúria, com o objetivo de evitar o aparecimento de hiperfosfatemia. Atualmente, o tratamento disponível para DRC é de manutenção e, portanto, novas estratégias para evitar a progressão da DRC seriam de grande relevância. Recentemente têm sido demonstrado o papel da célula-tronco mesenquimal (CTM) em minimizar os mecanismos inflamatórios e imunológicos envolvidos na progressão da DRC. Portanto, o estudo teve como hipótese de que a CTM possa evitar ou controlar a progressão para o HPTSR, investigada por meio da avaliação de biomarcadores do metabolismo de fósforo, ou seja, as concentrações sérica de fósforo (sP), FGF-23, cálcio total e cálcio ionizado, bem como a excreção fracionada de fósforo urinária (uFEP) em cães com DRC nos estágios 2 (Grupo A) e 3 (Grupo B), submetidos ou não a terapia com CTM, bem como investigar se os valores elevados de FGF-23 estariam relacionados com o menor tempo de sobrevida. Trata-se de um estudo prospectivo, longitudinal, duplo-cego e randomizado em que foram avaliados 22 cães com DRC, tratados com solução fisiológica (SF) ou CTM, avaliados a cada 30 a 45 dias em 12 momentos (T0 a T12). No Grupo A (n= 9; SF: n= 6, CTM: n= 3) todos os cães eram normofosfatêmicos no momento inicial do acompanhamento (T0) e foi observado níveis elevados de FGF-23 em 33,3% dos cães (3 de 9), assim como o aumento de uFEP foi detectado em 33,3% dos casos (3 de 9). A média ± EPM dos valores de FGF-23 sérico do Grupo A foi de 481,5 ± 75,23pg/mL. Já no Grupo B (n = 13; SF: n = 6, CTM: n = 7), todos os cães apresentaram altas concentrações séricas de FGF-23 desde T0 (média ± EPM de 12744 ± 6879pg/mL), sendo que 53,8% dos cães eram normofosfatêmicos. A média ± EPM de fósforo sérico em T0, T6 e T12 ou momento do óbito no Grupo A e B foi de 3,74 ± 0,13mg/dL e 6,40 ± 0,54mg/dL. Ao longo do curso da doença, o desenvolvimento de hiperfosfatemia foi observada em apenas 11,1% dos cães do Grupo A e em 84,6% dos cães do Grupo B. O Grupo B (SF e CTM) apresentou valores mais elevados de FGF-23 do que o Grupo A (SF e CTM), e foi detectada diferença estatística entre os dois grupos. A uFEP nos cães dos Grupos A e B em T0, T6 e T12 ou óbito obteve média ± EPM de 20,93 ± 3,92% e 24,05 ± 2,22%, respectivamente. Além disso, a sobrevida foi menor no Grupo B, a qual estava associada com hiperfosfatemia intensa, altas concentrações de FGF-23 e diminuição da uFEP. Dessa forma, em cães DRC normofosfatêmicos, a presença de aumentos de uFEP e de FGF-23 parece terem atuado como marcador precoce do HPTSR. Em contrapartida, nos estágios tardios da DRC, o aumento de FGF-23 associado a diminuição da uFEP pode indicar mau prognóstico. Em relação à terapia com CTM nos cães com DRC, de acordo com o número de cães avaliados e os resultados obtidos, não foi possível concluir de forma contundente sobre o efeito da terapia com CTM na doença renal crônica de curso natural em cães, entretanto, os resultados obtidos foram relevantes, pois suscitaram questões quanto ao momento ou o estágio da DRC que seria o mais adequado para a indicação da terapia celular para que os efeitos benéficos possam ser obtidos. Assim, ainda se faz necessária a condução de mais pesquisas com um número maior de cães com DRC para avaliar efeito da CTM em evitar o distúrbio no metabolismo mineral, bem como a progressão da DRC em cães / Hyperphosphatemia is associated with renal secondary hyperparathyroidism (SRHP) and chronic kidney disease (CKD) progression. Phosphorus retention stimulates the synthesis of fibroblast growth factor 23 (FGF-23), which promotes phosphaturia in order to avoid the onset of hyperphosphatemia. Conservative treatment of CKD is currently avaliable and new strategies are needed and welcome to avoid the progression of renal injury. Recent studies have shown the role of mesenchymal stem cell (MSC) in minimizing inflammatory and immunological mechanisms known as mediators of CKD progression. Therefore, it was hypothesized that MSCs could avoid or control the progression to SRHP, assessed by serum phosphorus (sP), FGF-23, total and ionized calcium and fractional excretion of phosphorus (uFEP) in CKD dogs in Stages 2 (Group A) and 3 (Group B), also was investigated whether high values of FGF-23 could be associatted with shorter survival time. Prospective, double-blind, randomized and longitudinal study was conducted enrolling 22 dogs with CKD treated with saline solution (SS) or MSC, which were evaluated every 30 to 45 days in 12 moments (T0 to T12). In Group A (n = 9; SF: n = 6, CTM: n = 3) all dogs were normophosphatemic at the beginning of the follow-up (T0) and high levels of FGF-23 were already detected in 33.3% of dogs (3 of 9), as well as increased in uFEP (33.3%; 3 of 9). The mean ± SEM of serum FGF-23 in Group A was 481.50 ± 75.23pg/mL. In Group B (n = 13; SS: n = 6, MSC: n = 7), all dogs showed high concentrations of serum FGF-23 since T0 (mean ± SEM of 12744 ± 6979pg/mL), and normophosphatemia detected in 53.8% of them. The mean ± SEM of serum phosphorus at T0, T6 and T12 or death in Group A and B was 3.74 ± 0.13mg/dL and 6.40 ± 0.54mg/dL. Hyperphosphatemia developed during the follow-up in only 11.1% of the dogs of Group A and 84.6% of the dogs of Group B. Group B (SS and MSC) had higher levels of FGF-23 than Group A (SS and MSC), and difference bewteen those groups detected. The uFEP in dogs of Groups A and B at T0, T6 and T12 or death obtained mean ± SEM of 20.93 ± 3.92% and 24.05 ± 2.22%, respectively. Furthermore, the survival rate was lower in Group B, which was associated with severe hyperphosphatemia, high values of serum FGF-23 and decreased uFEP. Therefore in normophophatemic CKD dogs, the increased in uFEP and high levels of FGF-23 may act as an early marker of SRHP. However, in later stages of CKD, increased levels of serum FGF-23 associated with decreased uFEP and hyperphosphatemia may indicate poor prognosis. Regarding to the MSC therapy in dogs with CKD, the number of dogs involved and also according to the results, it still has not allowed to conclude the effect of therapy with mesenchymal stem cell in spontaneous chronic kidney disease; however, the results obtained raised important questions such as the time or the stage of CKD that could be more suitable for the use of stem cell therapy in order to get its beneficial effects. Therefore, futher studies are needed, including greater number of dogs with CKD and then to evaluate the effect or action of MSC to avoid disturbances in mineral metabolism as well as the progression of CKD in dogs

A doença renal crônica (DRC) é a afecção renal mais frequente em cães e caracteriza-se pela progressiva redução do número de néfrons funcionais. Com a evolução da doença, os cães podem apresentar um conjunto de manifestações clínicas denominada uremia. O suporte nutricional objetiva atenuar os efeitos do estado urêmico, retardar a progressão da doença e melhorar a qualidade de vida dos animais. O presente estudo objetivou avaliar os efeitos da dieta coadjuvante e manejo dietético no metabolismo de cálcio e fósforo [fósforo, cálcio total (CaT), cálcio iônico (Cai), paratormônio (PTH) e FGF-23 séricos], escore de condição corporal (ECC), escore de massa muscular (EMM), concentrações séricas de aminoácidos (AAs) e citocinas inflamatórias (CIT), bem como a capacidade antioxidante total (CAT) de cães com DRC alimentados com dieta coadjuvante. Foram selecionados 10 cães com DRC estádios 3 e 4 (IRIS, 2015) provenientes do atendimento do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo. As variáveis PTH, FGF-23, AAs, CIT e CAT foram avaliadas no início do estudo (T0) e após 6 meses de manejo dietético (T6). As determinações séricas de ureia, creatinina, CaT, Cai e fósforo; ECC e EMM foram determinadas em T0 e a cada 30 dias, durante os 6 meses de estudo. Para a análise dos resultados, testes estatísticos paramétricos e não paramétricos foram empregados e valores de p&lt;0,05 foram considerados significativos. As concentrações séricas de ureia, fósforo, CaT, Cai, IL-6, IL-10, TNF-&#945;, CAT, PTH e FGF-23 não apresentaram diferença entre os momentos T0 e T6. A creatinina elevou-se em T6 (p=0,0022). Os AAs fenilalanina, triptofano e ornitina decresceram no tempo T6 (p=0,0273; p=0,0253; p=0,0443, respectivamente) e a hidroxiprolina aumentou em T6 (p=0,0073). As concentrações séricas de PTH apresentaram correlação com a creatinina e ureia (r=0,45, p&lt;0,05; r=0,67, p&lt;0,01; respectivamente). O Cai apresentou correlação negativa com a ureia (r=-0,59, p&lt;0,01) e o fósforo sérico apresentou correlação positiva com o FGF-23 (r=0,51; p&lt;0,05). A ureia e creatinina apresentaram correlação positiva (r=0,62; p&lt;0,01). De acordo com os resultados encontrados, conclui-se que a dieta e o manejo nutricional empregados foram eficazes no controle do hiperparatireoidismo secundário renal, estresse oxidativo, marcadores inflamatórios e na manutenção do escore de condição corporal, massa muscular e nutrição proteica dos cães avaliados. / Chronic kidney disease (CKD) is the most common kidney disease in dogs and characterized by progressive reduction in the number of functional nephrons. With the evolution of the disease the dogs may present a set of clinical manifestations denominated uremia. The efforts of nutritional support are to mitigate the effects of uremic state, slow the progression of the disease and improve the quality of life of the animals. The aim of this study was to evaluate the effects of prescription diet and dietary management on the metabolism of calcium and phosphorus [phosphorus, total calcium (CaT), ionized calcium (Cai), parathyroid hormone (PTH) and FGF-23 in the serum], body condition score (BCS), muscle mass score (MME), serum concentrations of amino acids (AAs) and inflammatory cytokines (CYT), as well as the total antioxidant capacity (TAC) of dogs with CKD fed with a coadjuvant diet. Were selected 10 dogs with CKD stage 3 and 4 (IRIS, 2015), from the Veterinary Hospital at School of Veterinary Medicine and Animal Science, University of São Paulo. The PTH, FGF-23, AAs, CYT and TAC variables were evaluated at baseline (T0) and after 6 months of dietary management (T6). The serum determinations of urea, creatinine, CaT, Cai and phosphorus; BCS and MMS were determined at T0 and every 30 days, for 6 months. For the analysis of the results, parametric and non-parametric statistical tests were used and values of p<0.05 were considered significant. Serum concentrations of urea, phosphorus, CaT, Cai, IL-6, IL-10, TNF-&#945;, CAT, PTH, FGF-23 did not differ between T0 and T6. Serum creatinine increased in T6 (p=0.0022). The AAs phenylalanine, tryptophan and ornithine decreased in T6 (p=0.0273; p=0.0253; p=0.0443, respectively) and hydroxyproline increased in T6 (p=0.0073). Serum PTH concentrations correlate positively with the concentrations of creatinine and urea (r=0.45, p&lt;0.05; r=0.67, p&lt;0.01; respectively). The Cai was negatively correlated with urea (r = -0.59, p&lt;0.01) and serum phosphorus was positively correlated with FGF-23 (r = 0.51; p&lt;0.05). The urea and creatinine were positively correlated (r=0.62; p&lt;0.01). It was concluded that diet and nutritional management were effective in the control of renal secondary hyperparathyroidism, oxidative stress, inflammatory markers and maintenance of body condition score, muscle mass and protein nutrition in the evaluated dogs.

A doença renal crônica (DRC) é a afecção renal mais frequente em cães e caracteriza-se pela progressiva redução do número de néfrons funcionais. Com a evolução da doença, os cães podem apresentar um conjunto de manifestações clínicas denominada uremia. O suporte nutricional objetiva atenuar os efeitos do estado urêmico, retardar a progressão da doença e melhorar a qualidade de vida dos animais. O presente estudo objetivou avaliar os efeitos da dieta coadjuvante e manejo dietético no metabolismo de cálcio e fósforo [fósforo, cálcio total (CaT), cálcio iônico (Cai), paratormônio (PTH) e FGF-23 séricos], escore de condição corporal (ECC), escore de massa muscular (EMM), concentrações séricas de aminoácidos (AAs) e citocinas inflamatórias (CIT), bem como a capacidade antioxidante total (CAT) de cães com DRC alimentados com dieta coadjuvante. Foram selecionados 10 cães com DRC estádios 3 e 4 (IRIS, 2015) provenientes do atendimento do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo. As variáveis PTH, FGF-23, AAs, CIT e CAT foram avaliadas no início do estudo (T0) e após 6 meses de manejo dietético (T6). As determinações séricas de ureia, creatinina, CaT, Cai e fósforo; ECC e EMM foram determinadas em T0 e a cada 30 dias, durante os 6 meses de estudo. Para a análise dos resultados, testes estatísticos paramétricos e não paramétricos foram empregados e valores de p&lt;0,05 foram considerados significativos. As concentrações séricas de ureia, fósforo, CaT, Cai, IL-6, IL-10, TNF-&#945;, CAT, PTH e FGF-23 não apresentaram diferença entre os momentos T0 e T6. A creatinina elevou-se em T6 (p=0,0022). Os AAs fenilalanina, triptofano e ornitina decresceram no tempo T6 (p=0,0273; p=0,0253; p=0,0443, respectivamente) e a hidroxiprolina aumentou em T6 (p=0,0073). As concentrações séricas de PTH apresentaram correlação com a creatinina e ureia (r=0,45, p&lt;0,05; r=0,67, p&lt;0,01; respectivamente). O Cai apresentou correlação negativa com a ureia (r=-0,59, p&lt;0,01) e o fósforo sérico apresentou correlação positiva com o FGF-23 (r=0,51; p&lt;0,05). A ureia e creatinina apresentaram correlação positiva (r=0,62; p&lt;0,01). De acordo com os resultados encontrados, conclui-se que a dieta e o manejo nutricional empregados foram eficazes no controle do hiperparatireoidismo secundário renal, estresse oxidativo, marcadores inflamatórios e na manutenção do escore de condição corporal, massa muscular e nutrição proteica dos cães avaliados. / Chronic kidney disease (CKD) is the most common kidney disease in dogs and characterized by progressive reduction in the number of functional nephrons. With the evolution of the disease the dogs may present a set of clinical manifestations denominated uremia. The efforts of nutritional support are to mitigate the effects of uremic state, slow the progression of the disease and improve the quality of life of the animals. The aim of this study was to evaluate the effects of prescription diet and dietary management on the metabolism of calcium and phosphorus [phosphorus, total calcium (CaT), ionized calcium (Cai), parathyroid hormone (PTH) and FGF-23 in the serum], body condition score (BCS), muscle mass score (MME), serum concentrations of amino acids (AAs) and inflammatory cytokines (CYT), as well as the total antioxidant capacity (TAC) of dogs with CKD fed with a coadjuvant diet. Were selected 10 dogs with CKD stage 3 and 4 (IRIS, 2015), from the Veterinary Hospital at School of Veterinary Medicine and Animal Science, University of São Paulo. The PTH, FGF-23, AAs, CYT and TAC variables were evaluated at baseline (T0) and after 6 months of dietary management (T6). The serum determinations of urea, creatinine, CaT, Cai and phosphorus; BCS and MMS were determined at T0 and every 30 days, for 6 months. For the analysis of the results, parametric and non-parametric statistical tests were used and values of p<0.05 were considered significant. Serum concentrations of urea, phosphorus, CaT, Cai, IL-6, IL-10, TNF-&#945;, CAT, PTH, FGF-23 did not differ between T0 and T6. Serum creatinine increased in T6 (p=0.0022). The AAs phenylalanine, tryptophan and ornithine decreased in T6 (p=0.0273; p=0.0253; p=0.0443, respectively) and hydroxyproline increased in T6 (p=0.0073). Serum PTH concentrations correlate positively with the concentrations of creatinine and urea (r=0.45, p&lt;0.05; r=0.67, p&lt;0.01; respectively). The Cai was negatively correlated with urea (r = -0.59, p&lt;0.01) and serum phosphorus was positively correlated with FGF-23 (r = 0.51; p&lt;0.05). The urea and creatinine were positively correlated (r=0.62; p&lt;0.01). It was concluded that diet and nutritional management were effective in the control of renal secondary hyperparathyroidism, oxidative stress, inflammatory markers and maintenance of body condition score, muscle mass and protein nutrition in the evaluated dogs.

BACKGROUND Vascular calcification is a major risk factor for cardiovascular morbidity and mortality in patients with end stage renal disease (ESRD). In Western countries, Blacks with ESRD appear to have lesser degrees of vascular calcification compared to non-Blacks. However, there is no published data on the association of ethnic differences in vascular calcification and survival in ESRD from Sub-Saharan Africa. METHODS This study assessed the 5-year change in vascular calcification and mortality in a previously published cohort of patients with ESRD. Vascular calcification was assessed by abdominal aortic calcification score (lateral abdominal radiograph) and vascular stiffness by pulse wave velocity. RESULTS Sixty-six of the original 74 participants, studied a baseline, were identified. The median age was 46.6 years (37.6-59.2) and 57.6% were women. Abdominal aortic calcification showed no progression among Blacks [baseline range 0-5, follow up range 0-8 (p=1.00)], but a nonsignificant trend to progression among non-Blacks [baseline range 0-19, follow up range 0-22 (p=0.066)]. Black participants did not display a survival advantage (p=0.870). Overall, sepsis was the most common cause of mortality (64% of those with an identifiable cause of death). Non-Blacks had higher parathyroidectomy rates than Blacks with 9/30 cases compared to 2/36 (p=0.036). After adjustment for parathyroidectomy at follow up, the odds ratio of having abdominal vascular calcification score of ≥1 amongst non-Blacks was 8.6-fold greater compared to Blacks (p= 0.03). Central aortic systolic pressures (CASP) and pulse wave velocities (PWV) were higher in the study population than age matched normative values. At follow up, a positive correlation (r=0.3) was observed between PWV and abdominal aortic calcification (p=0.04). Elevated baseline coronary artery calcification score and FGF-23 level at baseline were not associated with a difference in mortality. CONCLUSION There was no significant progression in vascular calcification among Blacks. After adjusting for increased parathyroidectomy rates, there was a greater progression of vascular calcification amongst non-Blacks compared to Blacks highlighting possible ethnic differences in calcium phosphate metabolism in patients with ESRD. The lack of vascular calcification progression in Blacks was not however associated with improved survival, but the sample size was small.

<p>Human physiology is dependent on an accurate phosphate (Pi) homeostasis. Defective Pi regulation causes hyper- or hypophosphatemia, which are associated with ectopic calcification or impaired bone mineralization, and a shortened life span. Current endocrine models of Pi homeostasis are incomplete. However, studies of acquired and hereditary disorders of Pi homeostasis have revealed new potential Pi regulating hormones, Phosphatonin(s). One of these is fibroblast growth factor-23 (FGF23). FGF23 is produced in bone and is secreted into the circulation. Mutations in FGF23 causes disturbed Pi regulation, without the appropriate counter-regulatory actions of parathyroid hormone or vitamin D. By the generation of FGF23 transgenic mice, which display phenotypic similarities to patients with hypophosphatemic disorders, we show that FGF23 exerts endocrine actions in the kidney and causes osteomalacia. Renal FGF23 actions severely decrease Pi reabsorption and expression of Klotho, a suggested age suppressor gene, known to be crucial in FGF23 receptor binding and activation. In bone, our transgenic model displays impaired osteoclast polarization, which should be detrimental to osteoclastic bone resorption in osteomalacia. However, in our model osteoclasts efficiently participate in bone matrix degradation. Furthermore, we investigated a large population-based cohort in order to elucidate the role of FGF23 in normal physiology. Importantly, we were able to demonstrate an association of FGF23 to parathyroid hormone, renal function and bone mineral density and we found a correlation of FGF23 to weight and body fat mass. The studies on which this thesis is based, demonstrate that FGF23 has phosphatonin-like properties and that the skeleton functions as an endocrine organ. In addition, the results indicate that FGF23 has a role in bone mineral and lipid metabolism, and that FGF23 is a possible diagnostic marker and therapeutic target for the future.</p>

Human physiology is dependent on an accurate phosphate (Pi) homeostasis. Defective Pi regulation causes hyper- or hypophosphatemia, which are associated with ectopic calcification or impaired bone mineralization, and a shortened life span. Current endocrine models of Pi homeostasis are incomplete. However, studies of acquired and hereditary disorders of Pi homeostasis have revealed new potential Pi regulating hormones, Phosphatonin(s). One of these is fibroblast growth factor-23 (FGF23). FGF23 is produced in bone and is secreted into the circulation. Mutations in FGF23 causes disturbed Pi regulation, without the appropriate counter-regulatory actions of parathyroid hormone or vitamin D. By the generation of FGF23 transgenic mice, which display phenotypic similarities to patients with hypophosphatemic disorders, we show that FGF23 exerts endocrine actions in the kidney and causes osteomalacia. Renal FGF23 actions severely decrease Pi reabsorption and expression of Klotho, a suggested age suppressor gene, known to be crucial in FGF23 receptor binding and activation. In bone, our transgenic model displays impaired osteoclast polarization, which should be detrimental to osteoclastic bone resorption in osteomalacia. However, in our model osteoclasts efficiently participate in bone matrix degradation. Furthermore, we investigated a large population-based cohort in order to elucidate the role of FGF23 in normal physiology. Importantly, we were able to demonstrate an association of FGF23 to parathyroid hormone, renal function and bone mineral density and we found a correlation of FGF23 to weight and body fat mass. The studies on which this thesis is based, demonstrate that FGF23 has phosphatonin-like properties and that the skeleton functions as an endocrine organ. In addition, the results indicate that FGF23 has a role in bone mineral and lipid metabolism, and that FGF23 is a possible diagnostic marker and therapeutic target for the future.

Fibroblast growth factor 23 (FGF-23) has recently been shown to be involved in phosphate regulation and bone mineralization. This study evaluated the effect of FGF-23 on three human cell lines (Caco-2, HK-2, SaOS-2) representing three different sites of phosphate regulation (small intestine, kidney proximal tubules, and bone, respectively). FGF-23 induced gene expression was studied using Clontech human Atlas glass microarrays containing various assortments of genes and by a custom designed oligo microarray containing specific genes selected for their biological relevance to FGF-23's potential function. FGF-23 induced differential gene expression in all three cell types, suggesting that FGF-23 may be capable of acting on these three primary sites of phosphate regulation. Human small intestine-like endothelial cell line, Caco-2, showed upregulation of several genes including parathyroid hormone receptors 1 and 2. FGF-23 inhibited the expression of water channel transporters aquaporin 5 and 6 in human osteoblast-like SaOS-2 cells while upregulating aquaporin expression in HK-2 cells. Somatostatin receptors 1-4 were identified to be upregulated in the human kidney, HK-2 cell line. Mucin 2, a gene that is linked to abnormal cellular growth, was consistently induced by FGF-23 in all three cell lines. Families of aquaporins, somatostatins, parathyroid hormones, and other identified differentially expressed genes are involved in different signaling pathways that are associated with phosphate and calcium regulation. Selected candidates were analyzed further by real-time RT-PCR. These data support FGF-23 induced regulation of aquaporin 5 mRNA in HK-2 cells and 1-alpha-hydroxylase mRNA in Caco cells. FGF-23 induced changes in mRNA analysis of four additional genes was less than two-fold in triplicate analysis of selected samples. Taken together, these results suggest that each cell type may have responded to FGF-23, but additional validation of the array data set will be required to identify those genes specifically regulated by FGF-23. Further refinement of this data set will undoubtedly uncover additional functions of FGF-23 and may provide valuable insight into designing therapeutic approaches for phosphate specific disorders.

L'insuffisance rénale chronique (IRC) demeure un problème de santé publique du fait de l'augmentation de sa prévalence. Malgré l'amélioration de la prise en charge, le taux de mortalité reste plus élevé comparé à la population générale. Parmi les causes de décès, les maladies cardiovasculaires, d'origine multifactorielle (élargissement et hypertrophie des artères, athérosclérose, calcifications vasculaires et valvulaires) sont au premier plan. A côté des facteurs de risque classiques, des facteurs non traditionnels, liés aux perturbations métaboliques de l'IRC, ont été mis en évidence, comme l'inflammation, la malnutrition, le stress oxydant, les anomalies du métabolisme minéralo-osseux. La meilleure connaissance de la physiopathologie de la vasculopathie de l'IRC permet d'émerger de nouveaux biomarqueurs pour stratifier le risque cardiovasculaire chez l'IRC.OBJECTIFS-METHODOLOGIE GENERALE : Nous avons réalisé une approche biochimique pour explorer trois composantes du risque cardiovasculaire chez l'IRC : stress oxydant, perturbations qualitatives des HDL (high-density lipoprotein) et métabolisme minéralo-osseux.RESULTATS : Dans une première publication la production d'anion superoxyde a été évaluée, via une méthode de chemoluminescence, en fonction du stade de l'IRC. Alors que la surproduction de formes réactives de l'oxygène est bien connue au stade 5d et peut être liée à la procédure dialytique, il existe peu de données aux stades précoces. Notre étude a porté sur 136 patients IRC non dialysés des stades 1à 5. Les résultats montrent que la production de FRO est assurée aux stades 4 et 5. Un bas débit de filtration glomérulaire (MDRD<30ml/min/1.73m2), l'inflammation (fibrinogène >3.7g/l) et des taux anormaux d' HDL (<1.42mM et >1.75mM) apparaissent comme les principaux déterminants du stress oxydant chez l'IRC non dialysé.Alors que dans la population générale, un taux bas de HDL est reconnu comme un facteur de risque important, nous avons montré (publication 1) que des taux anormaux de HDL, bas comme hauts, étaient indépendamment associés au stress oxydant chez les sujets IRC. Dans une deuxième publication, nous avons précisé la composition des HDL en se basant sur d'éventuelles modifications qualitatives des protéines associées à la structure des lipoprotéines. Une étude protéomique a été réalisée chez 7 patients hémodialysés versus 7 sujets sains. Nous avons retrouvé 40 protéines exprimées différemment sur les 122 identifiées, dont l'apoCII, l'apoCIII qui sont significativement augmentées et la transferrine abaissée. Ces protéines interviennent dans de nombreuses fonctions comme la réponse inflammatoire, l'activation du complément, la régulation de l'oxydation des lipoprotéines, l'homéostasie des cations.Dans une troisième publication, l'épuration du FGF23, phosphatonine impliquée dans les anomalies du métabolisme minéralo-osseux, été étudiée chez l'hémodialysé chronique en fonction de la techniques de dialyse (hémodialyse (HD) high flux versus hémodiafiltration on line (OL-HDF)). Notre étude a porté sur 53 patients dans le groupe HD et 32 patients dans le groupe OL-HDF. Dans les deux groupes le taux de FGF23 en post-dialyse est significativement plus bas qu'en pré-dialyse. Cependant, le taux de réduction, la clairance et le KT/V du FGF23 sont significativement plus bas dans le groupe OL-HDF.CONCLUSION-PERSPECTIVES : Chez l'IRC, avec l'appariation de facteurs de risque non traditionnels, de nouveaux biomarqueurs ont émergés dans la stratification du risque cardio-vasculaire. Ces biomarqueurs peuvent devenir des bioacteurs et représenter de nouvelles cibles d'action et de prévention de l'atteinte cardio-vasculaire chez l'IRC. La complexité des mécanismes physiopathologiques impliqués, nous incite à proposer des approches multimarqueurs. Actuellement des études biocliniques se poursuivent en mettant en place des cohortes régionales de patients aux stades 1 à 5 et de patients incidents en dialyse. / BACKGROUND: Chronic kidney disease (CKD) is a public health problem because of its increasing prevalence. Despite care improvements, the mortality rate remains higher compared to general population. Among causes of death, cardiovascular diseases with multifactorial origins (enlargement and hypertrophy of arteries, atherosclerosis, vascular and valvular calcifications) are in the foreground. Besides the traditional risk factors, non-traditional factors associated with metabolic disorders in CKD were bring out, such as inflammation, malnutrition, oxidative stress, mineral and bone disorder. A better knowledge of vasculopathy physiopathology in CKD allows the emergence of new biomarkers to stratify cardiovascular risk in CKD.AIMS-METHODOLOGY: We performed a biochemical approach to explore three components of cardiovascular risk in CKD: oxidative stress, qualitative alterations of HDL (high-density lipoprotein) and mineral and bone disorder.RESULTS: In a first publication, the superoxide anion production, according to the stage of CKD, was assessed using a chemiluminescence method. While the overproduction of reactive oxygen species is well known at the 5d stage of CKD and may be related to the dialysis procedure, there are few data in the early stages. Our study included 136 non-dialysis patients at stages 1 to 5 of CKD. Results showed an enhanced superoxide production at the pre-dialysis phase, stages 4 and 5 of CKD. Reduced glomerular filtration rate (MDRD <30 ml / min / 1.73m2), inflammation (fibrinogène≥3.7g / l) and abnormal levels of HDL (<1.42mM and ≥1.75mM) appears as main determinants of oxidative stress in non-dialysis CKD patients.While in general population, a low HDL rate is recognized as an important risk factor, we showed (publication 1) that abnormal levels of HDL, low as high, were independently associated with oxidative stress in CKD subjects. In a second publication, we have defined the HDL composition based on qualitative changes in the structure of proteins associated with lipoproteins. A proteomic study was performed in 7 patients on hemodialysis versus 7 healthy subjects. We found 40 proteins differently expressed on the 122 identified, including apoCII, apoCIII which are significantly increased and transferrin lowered. These proteins are involved in many functions such as inflammatory response, complement activation, regulation of lipoprotein oxidation and homeostasis cations. In a third publication, the removal of FGF23, phosphatonin involved in mineral and bone metabolism, was studied in chronic hemodialysis according to the dialysis techniques (high flux hemodialysis (HD) versus on line hemodiafiltration (OL- HDF)). Our study included 53 patients in the HD group and 32 patients in the OL-HDF group. In both groups the rate of FGF23 in post-dialysis was significantly lower than in pre-dialysis. However, rate of reduction, clearance and KT / V of FGF23 were significantly lower in the OL-HDF group.CONCLUSION-PROSPECTS: In the IRC, with the appearance of non traditional risk-factors, new biomarkers have emerged in the stratification of cardiovascular risk. These biomarkers can become bioactors and represent novel targets of action and prevention in the cardiovascular disease in CKD. The complexity of the involved physiopatholological mechanisms, leads us to propose multimarkers approaches. Currently bioclinical studies continue with the constitution of regional cohorts of patients at stages 1 to 5 of CKD and incident dialysis.

Fibroblast growth factor-23 (FGF23) is a novel, bone-produced hormone that regulates renal phosphate (Pi) reabsorption and calcitriol metabolism. Disorders of mineral and bone metabolism, such as autosomal dominant hypophosphatemic rickets (ADHR) and hyperostosis-hyperphosphatemia syndrome (HHS), witness the importance of well-balanced serum levels of FGF23. Patients with chronic kidney disease (CKD) are highly morbid due to Pi retention/hyperphosphatemia and calcitriol deficiency, which lead to elevated serum levels of parathyroid hormone (PTH) and secondary hyperparathyroidism (sHPT). As a response to hyperphosphatemia, CKD patients have also remarkably high serum FGF23 levels, which are associated with cardiovascular risk factors and increased mortality in CKD. The overall aim of this dissertation was to discern a possible role of FGF23 in parathyroid biology. Our in vitro experiments on isolated bovine parathyroid cells demonstrate that FGF23 directly and dose-dependently suppresses the PTH production and secretion, while increasing the expression of the 25-hydroxyvitamin D3-activating enzyme 1α-hydroxylase. We investigated possible expressional changes in the FGF23 receptor co-factor Klotho in hyperparathyroid disorders and found that Klotho expression is decreased or absent and inversely correlated to serum calcium (Ca) in adenomas of primary HPT (pHPT). In the hyperplastic parathyroid glands of sHPT, Klotho expression declines in parallel with the kidney function and correlates with the glomerular filtration rate. Moreover, Klotho expression is suppressed by Ca and FGF23, increased by calcitriol, but unaffected by Pi and PTH in vitro. Finally, we identified a novel missense mutation in the gene encoding GALNT3, which is normally involved in the post-translational glycosylation of FGF23, as the cause of aberrant FGF23 processing in a patient with HHS. In summary, we provide evidence for a novel bone/parathyroid axis in which FGF23 functions as a direct, negative regulator of the PTH production. High extracellular Ca is a major determinant of the Klotho expression in pHPT, whereas the Klotho levels in sHPT may be attributed to a combination of the high FGF23 and Ca, and low calcitriol levels associated with CKD. Hence, the decreased Klotho expression in sHPT could explain the concomitantly high FGF23 and PTH levels, as well as the failure of FGF23 to prevent or mitigate the development of sHPT in CKD.