L’insuffisance rénale chronique (IRC) est associée à une diminution de la clairance métabolique des médicaments résultant en partie de l’inhibition des cytochromes P450 (CYP450) et des enzymes de phase II, notamment la N-acétyltransférase 2 (NAT2), tel que démontré chez le rat. Nous avons précédemment démontré le rôle de l'hormone parathyroïdienne (PTH) dans la diminution des CYP450 hépatiques chez le rat souffrant d’IRC. Toutefois, l’étude des mécanismes sous-jacents pouvant être facilitée par l’utilisation de souris transgéniques, l’objectif de cette étude consiste à confirmer ces résultats dans un modèle murin. D’abord, afin de valider ce modèle expérimental, une IRC a été induite par néphrectomie subtotale 3/4 chez des souris C57BL/6, puis l’expression protéique et génique des CYP450 et de la Nat2 hépatiques a été étudiée. Les résultats indiquent que l’IRC induit effectivement une diminution d’expression de ces enzymes dans un modèle murin. Ensuite, des souris mutantes pour le gène codant la PTH (PTH-/-) et les souris correspondantes de type sauvage (PTH+/+) ont été néphrectomisées, puis l’expression protéique et génique des CYP450 hépatiques a été analysée. Si la PTH est responsable de la diminution du CYP450 en situation d’IRC, les souris PTH-/- atteintes d’IRC ne devraient présenter aucune baisse d’expression. Les résultats obtenus pour les souris PTH-/- ne peuvent être interprétés, puisque chez les souris PTH+/+ atteintes d'IRC, le CYP450 hépatique est inchangé par rapport aux souris PTH+/+ témoins. Des expériences supplémentaires seront requises afin de déterminer si la régulation à la baisse du CYP450 précédemment observée est contrecarrée par l’absence de PTH. / Chronic renal failure (CRF) is associated with a decrease in the metabolic clearance of drugs, which is partly due to a reduced expression of cytochrome P450 (CYP450) and phase II enzymes, namely N-acetyltransferase 2 (NAT2). This phenomenon has been shown in the rat. We have previously demonstrated the role of parathyroid hormone (PTH) in CYP450 down-regulation in rats with CRF. However, the study of mechanisms underlying the down-regulation of CYP450 by PTH should be confirmed with the use of knockout mice. The aim of this study was, therefore, to confirm these results in a murine model. Firstly, to validate this experimental model, CRF was produced in C57BL/6 mice using the 3/4 subtotal nephrectomy. Protein and mRNA levels of hepatic CYP450 and Nat2 were then analyzed. The results showed that CRF down-regulates these enzymes, as previously observed in the rat. Finally, PTH-null mice (PTH-/-) and their corresponding wild type (PTH+/+) were nephrectomized in order to analyze protein and mRNA expression of hepatic CYP450. If PTH is responsible for the decrease of CYP450 in the presence of CRF, then PTH-/- mice with CRF should not show any reduction in CYP450 expression compared to controls. The results concerning the PTH-/- mice could not be interpreted because PTH+/+ mice with CRF did not show any significant difference of CYP450 expression when compared to PTH+/+ controls. Thus, additional experiments must be conducted in order to determine the role of PTH in CYP450 down-regulation in CRF mice.

Le développement et l'homéostasie des os requièrent l'orchestration spatio-temporelle d'un grand nombre de signaux moléculaires. Ces signaux entraînent l'activation ou l'inhibition de différents facteurs de transcription, lesquels sont en mesure de contrôler la prolifération et la différenciation des ostéoblastes et des chondrocytes. L'intégrité de ces différents mécanismes se doit d'être maintenu tout au long de la vie. Ainsi, une anomalie dans l'un de ces mécanismes conduit à l'apparition de pathologies osseuses et métaboliques telles qu’une hypophosphatémie, l'ostéoporose ou l'ostéoarthrite (OA). Afin d'en apprendre davantage sur la biologie osseuse, le projet décrit dans cette thèse a pour objectif de caractériser de nouveaux mécanismes de régulation transcriptionnelle pour deux gènes importants dans le développement des os et le maintien de leur intégrité. Il s’agit du Paired-like Homeodomain Transcription Factor 1 (PITX1) et du Phosphate-regulating gene with homology to endopeptidase on the X chromosome (PHEX). Le premier mécanisme présenté dans cette thèse concerne la régulation transcriptionnelle du gène PITX1, un facteur de transcription à homéodomaine nécessaire, notamment, au développement des os des membres inférieurs et au maintien de l'intégrité du cartilage articulaire chez l'adulte. Ainsi, dans les chondrocytes articulaires, on note que l'expression de PITX1 est assurée par le recrutement du facteur de transcription E2F1 à deux éléments de réponse présents dans la région proximale du promoteur de PITX1. Aussi, dans les chondrocytes articulaires de patients souffrant d'OA, dans lesquels l'expression de PITX1 est fortement diminuée, un mécanisme de répression transcriptionnelle, lequel implique la protéine multifonctionnelle Prohibitin (PHB1), semble être activé. En effet, dans ces chondroytes, on note une forte accumulation nucléaire de PHB1 comparativement aux chondrocytes articulaires de sujets sains. Le second mécanisme présenté dans cette thèse concerne la répression transcriptionnelle de PHEX, la peptidase mutée dans le syndrome d'hypophosphatémie lié au chromosome X (X-Linked Hypophosphatemia, XLH), lequel se caractérise par une hypophosphatémie et une ostéomalacie. Le traitement d'ostéoblastes à la Parathyroid hormone-related protein (PTHrP) permet d’observer la répression de PHEX. Afin de caractériser le mécanisme responsable de cette répression, des expériences de gènes rapporteurs ont révélé la présence de deux éléments de réponse pour le répresseur transcriptionnel E4BP4 dans le promoteur de PHEX. La suppression de l'expression d'E4BP4 par l'utilisation d'ARN d'interférence a permis de valider que ce facteur de transcription est responsable de la répression de PHEX suite au traitement d'ostéoblastes à la PTHrP. En somme ces nouveaux mécanismes de régulation transcriptionnelle permettent de mieux comprendre la régulation de l'expression de PITX1 et de PHEX. Aussi, cette nouvelle implication de PHB1 dans la pathogenèse de l'OA offre de nouvelles possibilités de traitement et pourrait servir pour le diagnostic précoce de cette pathologie. Enfin, la caractérisation d'E4BP4 en tant que médiateur pour la répression de PHEX par la PTHrP suggère que ce répresseur transcriptionnel pourrait être impliqué dans le contrôle de la minéralisation des os et des niveaux de phosphate sanguin. / Bone development and homeostasis need a large amount of molecular signals to be finely regulated in time and space. These signals lead to the activation or to the inhibition of different transcription factors, which are implicated in the control of osteoblast and chondrocyte proliferation and differentiation. The integrity of these mechanisms is required in order to have a healthy life. Indeed, if one of these mechanisms is dysfunctional, different diseases could develop such as hypophosphatemia, osteoporosis and osteoarthritis (OA). In order to contribute to the comprehension of bone biology, the present thesis describes new mechanisms for the transcriptional regulation of two genes implicated in bone development and regulation: PITX1 (Paired-like Homeodomain Transcription Factor 1) and PHEX (Phosphate-regulating gene with homology to endopeptidase on the X chromosome). The first mechanism described in this thesis relates to the transcriptional regulation of PITX1, a gene that encodes for a member of the homeobox family of transcription factors. PITX1 is required in bone development of inferior members and in the maintenance of the articular cartilage integrity in adults. Thereby, we showed that in articular chondrocytes, the expression of PITX1 is activated after the transcription factor E2F1 was recruited at two response elements in the proximal region of its promoter. Moreover, in articular chondrocytes from OA patients, we observed that the expression of PITX1 is strongly decreased. We proposed that the mechanism responsible for this repression requires the multitask protein Prohibitin (PHB1), which is strongly accumulated in OA chondrocyte nuclei, but not in chondrocyte nuclei from healthy individuals. The second mechanism described in this thesis reports a transcriptional mechanism by which PHEX, the gene that encodes for the peptidase mutated in the syndrome X-Linked Hypophosphatemia (XLH)and characterized by hypophosphatemia and osteomalecia, is repressed. We showed that the treatment of osteoblasts with the Parathyroid hormone-related protein (PTHrP) induced a decrease in PHEX expression. In order to characterize the mechanism responsible for this repression, we performed gene reporter experiments and identified two response elements for the transcription factor E4BP4 in the PHEX promoter. The downregulation of E4BP4 by siRNA led to the validation that this repressor decreased the expression of PHEX in osteoblasts after their treatment with PTHrP. In conclusion, the new transcriptional mechanisms presented in this thesis allow a better understanding of PITX1 and PHEX expression. Moreover, the potential role of PHB1 in the establishment of OA presents many interesting possibilities regarding the treatment and diagnosis of this disease. Finally, the characterization of E4BP4 as a mediator of PHEX repression by the PTHrP suggests that E4BP4 could be implicated in the control of bone mineralization and phosphate levels in the blood.

Inúmeros estudos têm demonstrado elevada prevalência de hipovitaminose D (deficiência/insuficiência de 25(OH)D) em indivíduos normais e em pacientes com e sem doença renal. Como os pacientes transplantados renais têm maior risco de desenvolver câncer de pele, são orientados a evitar exposição ao sol e usar filtro solar. A combinação de doença renal crônica (DRC) e menor exposição ao sol contribuem para que esses pacientes desenvolvam hipovitaminose D, o que pode piorar ou favorecer o desenvolvimento de doença óssea. O objetivo desse estudo foi avaliar a concentração sérica de 25(OH)D e a prevalência de hipovitaminose D em uma amostra representativa (N=149) de pacientes transplantados renais do Hospital das Clinicas da Universidade de São Paulo. Avaliamos ainda se a hipovitaminose poderia ser atribuída a menor exposição ao sol ou ingestão insuficiente de alimentos fontes. Comparamos os níveis séricos de 25(OH)D desses pacientes com o de indivíduos normais. Hipovitaminose D, definida pelos níveis séricos de 25(OH)D menores que 30 ng/ml, foi observada em 79% dos pacientes transplantados e o principal fator determinante foi a menor exposição ao sol.Os níveis séricos de creatinina e de paratormônio (PTH) foram significativamente mais elevados nos pacientes com hipovitaminose quando comparados aos com níveis normais de 25(OH)D. Observamos uma correlação inversa dos níveis séricos de 25(OH)D com os de paratormônio (r= -0,24; p<0,03). A prevalência de hipovitaminose D foi maior nos pacientes transplantados que nos indivíduos normais. Os níveis séricos de creatinina e PTH foram mais elevados nos transplantados, enquanto os de Ca, P e albumina menores que dos indivíduos normais. Em conclusão: A hipovitaminose D é freqüente nos pacientes transplantados renais e orientação dietética, exposição solar curta e regular ou mesmo a suplementação com vitamina D seriam medidas simples para assegurar níveis adequados dessa vitamina / Recent epidemiological studies have shown a high prevalence vitamin D deficiency in normal population and in patients with and without kidney diseases. In addition, kidney transplant patients are at higher risk for skin cancer, so they are advised to avoid sun and use sunscreen. Because of the combination of chronic kidney disease (CKD) and sun avoidance, kidney transplant patients are at high risk for developing hypovitaminosis D. We evaluated serum 25 vitamin D levels in a representative sample (N = 149) of kidney transplant patients from the University of São Paulo Transplant Unit. Our objectives were to determine the prevalence of hypovitaminosis D, comparing them to normal volunteers, as well as, to identify the factors that could be associated with this decrease in serum 25 vitamin D, such as sun exposure and dietary habits. Hypovitaminosis D, defined by serum levels < 30 ng/mL, was found in 79% of kidney transplant patients, and the main associated factor was low sun exposure. Patients that presented hypovitaminosis D had higher serum creatinine and parathormone (PTH) levels. Serum 25 vitamin D correlated with serum PTH (r= - 0.24; p=0.03). When compared to normal volunteers, renal transplant patients presented a higher prevalence of hypovitaminosis D, as well as low serum calcium, phosphate albumin, and higher creatinine, and PTH. Our results confirm a high prevalence of hypovitaminosis D in renal transplant patients. In conclusion, hypovitaminosis D is frequent in kidney transplant patients, therefore dietary orientation, short or regular sun exposure, and vitamin D supplementation are important determinants of vitamin D status

O objetivo deste estudo foi analisar o metabolismo ósseo de pacientes com proteinúria glomerular sem uso prévio de drogas que afetassem esse metabolismo. Dezessete pacientes foram estudados com biópsia óssea para análise histomorfométrica e fragmentos ósseos foram obtidos para cultura de célula (n=13) na qual nós avaliamos proliferação de osteoblasto. A comparação dos achados histomorfométricos a controles de literatura demonstrou uma diminuição da remodelação óssea e comprometimento de sua microarquitetura. Corroborando com esse resultado houve diminuição da proliferação dos osteoblastos dos pacientes quando comparados a controles (n=5) doadores de órgãos. Análise bioquímica revelou correlação negativa da 25(OH)D3 com a proteinúria e positiva com a proliferação dos osteoblastos em cultura / The objective of this study was to analyze bone metabolism in proteinuria glomerular patients not having previously used drugs affecting bone metabolism. Seventeen patients were studied with histomorphometric analysis of bone biopsies and bone fragments were obtained for cell culture (n = 13), in which we evaluated osteoblastic proliferation. Comparing patients to controls of literature indicate reduced bone remodeling and altered bone microarchitecture. In corroboration, mean osteoblast proliferation was lower in patient samples when compared with those for normal osteoblasts obtained from age-matched, gender-matched donor organs (n = 5). Concentrations of 25-hydroxyvitamin-D3 correlated negatively with proteinuria and positively with osteoblast proliferation in culture

INTRODUÇÃO: A primeira doença humana atribuída à resistência hormonal foi o pseudo-hipoparatireoidismo (PHP), uma doença rara caracterizada por hipocalcemia, hiperfosfatemia e níveis elevados de hormônio paratireoidiano (PTH) na presença de função renal normal, quadro condizente com resistência ao PTH. A classificação original do PHP leva em consideração a osteodistrofia hereditária de Albright (AHO): presente no PHP1a e ausente no PHP1b. Na medida em que as bases moleculares do PHP têm sido compreendidas, uma classificação baseada no genótipo tem surgido. Segundo ela, pacientes com PHP1a apresentam mutações na região codificadora da Gsalfa do GNAS e o padrão de herança é autossômico dominante relacionado à transmissão materna. Por outro lado, o PHP1b é caracterizado por alterações nas regiões diferencialmente metiladas (DMRs) do GNAS por mecanismos não completamente esclarecidos, limitando a previsão do seu padrão de herança. Pacientes que apresentam a AHO na ausência de resistência hormonal têm o diagnóstico de pseudopseudo-hipoparatireoidismo (PPHP) e seu padrão de herança é autossômico dominante relacionado à transmissão paterna de mutações na região codificadora da Gsalfa do GNAS. OBJETIVOS: Classificar 25 pacientes com PHP com base em defeitos no GNAS e caracterizar seu fenótipo. Pesquisar mutações no GNAS nos quatro pacientes com PPHP e também caracterizar seu fenótipo. MÉTODOS: A avaliação fenotípica incluiu análise das resistências hormonais, pesquisa de repercussões crônicas da hipocalcemia/hiperfosfatemia (calcificações em sistema nervoso central: SNC e catarata) e identificação da AHO. A análise do GNAS foi feita por sequenciamento automático e MLPA (região codificadora da Gsalfa) e por MS-MLPA (região regulatória: DMRs). RESULTADOS: Resistência ao PTH foi identificada nos 25 pacientes com PHP e resistência ao TSH em 17/25. Calcificações em SNC e catarata estiveram presentes em 18 e 10 pacientes com PHP, respectivamente. A AHO foi caracterizada por: face arredondada (n=18), braquidactilia (n=11), baixa estatura (n=8), ossificações subcutâneas (n=6), obesidade (n=9) e retardo mental (n=3). Identificamos oito mutações (cinco novas) na região codificadora da Gsalfa em 10 pacientes com PHP1a e quatro pacientes com PPHP. Quinze pacientes apresentaram alteração no padrão de metilação das DMRs (genótipo: PHP1b). O fenótipo dos pacientes foi semelhante nos dois grupos. DISCUSSÃO E CONCLUSÃO: Nenhuma das classificações do PHP foi capaz de predizer gravidade ou o curso clínico da doença. Porém, o diagnóstico do PHP1a baseado no genótipo possibilitou a identificação precoce de uma paciente, a exclusão de PHP1a na filha de outra paciente e o aconselhamento genético em duas famílias. O diagnóstico de PHP1b em uma paciente só foi possível graças ao genótipo, visto que seu perfil laboratorial osteometabólico era inconclusivo. Com base no fenótipo, 8/15 pacientes com PHP1b seriam classificados como PHP1a considerando a presença de dois ou mais estigmas da AHO, podendo levar a falhas no aconselhamento genético. Portanto, concluímos que a classificação do PHP baseada na análise do GNAS é mais informativa do que a baseada no fenótipo, permitindo o diagnóstico precoce e o aconselhamento genético de casos familiais de PHP1a. A identificação do PHP1b deve ser promissora na medida em que seus mecanismos de transmissão forem mais bem entendidos / BACKGROUND: The first human disease attributed to hormone resistance was pseudohypoparathyroidism (PHP), a rare disease characterized by hypocalcemia, hyperphosphatemia and elevated parathyroid hormone (PTH) levels in the presence of normal renal function, consistent picture of PTH resistance. The original classification of PHP takes into account the Albright hereditary osteodystrophy (AHO): present in PHP1a and absent in PHP1b. As the molecular bases of PHP have been understood, a classification based on genotype has emerged. According to it, PHP1a patients present mutations in the Gsalpha coding region of the GNAS and the pattern of inheritance is autosomal dominant related to maternal transmission. On the other hand, PHP1b is characterized by alterations in differentially methylated regions (DMRs) of the GNAS by mechanisms not completely clear, limiting the prediction of the pattern of inheritance. Patients who present AHO in the absence of hormone resistance have the diagnosis of pseudopseudohypoparathyroidism (PPHP) and their pattern of inheritance is autosomal dominant related to paternal transmission of mutations in the Gsalfa coding region of the GNAS. OBJECTIVE: To classify 25 patients with PHP based on GNAS molecular defects and to characterize their phenotype. To search for GNAS mutations in four patients with PPHP and also to characterize their phenotype. METHODS: The phenotypic evaluation included analysis of hormone resistances, research of chronic repercussions of hypocalcemia/hyperphosphatemia (calcifications in central nervous system: CNS and cataract) and identification of AHO. The analysis of the GNAS was done by automated sequencing and MLPA (Gsalphaa coding region) and by MS-MLPA (regulatory region: DMRs). RESULTS: PTH resistance was identified in 25 patients with PHP and TSH resistance in 17/25. Calcifications in CNS and cataract were present in 18 and 10 patients with PHP, respectively. AHO was characterized by: rounded face (n=18), brachydactyly (n=11), short stature (n=8), subcutaneous ossifications (n=6), obesity (n=9) and mental retardation (n=3). We identified eight mutations (five novels) in the Gsalpha coding region in 10 patients with PHP1a. Fifteen patients presented alterations in the methylation pattern of DMRs (genotype: PHP1b). The phenotype of patients was similar in both groups. DISCUSSION AND CONCLUSION: None of the PHP classifications was able to predict the severity or clinical course of the disease. However, the diagnosis of PHP1a based on genotype allowed the early identification of one patient, the exclusion of PHP1a in the daughter of another patient and genetic counseling in two families. The PHP1b diagnosis in one patient was only possible due to the genotype, as her bone metabolism profile was inconclusive. Based on phenotype, 8/15 PHP1b patients would have been classified as PHP1a considering the presence of two or more AHO stigmas, being able to lead to failures in genetic counseling. Therefore, we conclude that the PHP classification based on GNAS analysis is more informative than that based on phenotype, allowing the early diagnosis and the genetic counseling for familial cases of PHP1a. The identification of PHP1b may be promising as its transmission mechanisms are better clarified

INTRODUÇÃO: O distúrbio mineral e ósseo (DMO) contribue significativamente para a redução da sobrevida em pacientes em terapia renal substibutiva (TRS). Os artigos que tratam do assunto, em sua grande maioria, envolvem pacientes submetidos a hemodiálise (HD) e essas publicações embasam as principais diretrizes (Kidney Disease Outcomes Quality Initiative - KDOQI - e o Kidney Disease: Improving Global Outcomes - KDIGO). MÉTODOS: Utilizamos a base de dados do Brazilian Peritoneal Dialysis (BRAZPD), estudo multicêntrico prospectivo, observacional, que avaliou pacientes em diálise peritoneal (DP), entre dezembro de 2004 e janeiro de 2011. Dos 9905 pacientes incluídos nessa base, selecionamos 844 que apresentavam dados demográficos, clínicos e laboratoriais completos e tempo em DP superior a 6 meses. Esse grupo de pacientes foi avaliado no seguimento de 24 meses. As variáveis de confusão foram corrigidas por modelos estatísticos (Cox e competing risk) e os níveis séricos de cálcio (Ca), fósforo (P) e paratormônio (PTH) relacionados com a sobrevida dos pacientes. RESULTADOS: Encontramos níveis menores de relative hazard quando os pacientes apresentavam valores de Ca e P próximos a 9,7 e 5,0 mg/dL, respectivamente. Encontramos significância estatística ao associar os níveis de Ca categorizados, conforme a orientação do KDIGO (Ca: 8,4 - 10,2 mg/dL, p = 0,03), e a sobrevida. Da mesma forma foi encontrada associação entre os níveis de P e a sobrevida dos pacientes, categorizados segundo as recomendações do KDOQI e KDIGO (P: 3,5 - 5,5 mg/dL, p < 0,01, para ambos). Outros limites de Ca (8,6 - 10,3 mg/dL, p < 0,01) e P (3,5 - 6,7 mg/dL, p < 0,01), encontrados nesse estudo, mostraram risco adicional. Apesar dos pacientes com níveis de PTH próximos a 532 pg/mL apresentarem menor relative hazard, não encontramos diferença significativamente estatística para sobrevida quando categorizados para valores de PTH tanto conforme o KDOQI (150 - 300 pg/mL) quanto para o KDIGO (150- 600 pg /mL). CONCLUSÕES: Em conclusão, manter os níveis de Ca conforme as orientações do KDIGO e P conforme orientações das duas diretrizes mostraram-se eficazes para melhora da sobrevida. Valores de Ca e P, propostos por esse estudo, evidenciaram risco adicional quando os valores ultrapassaram 8,6 - 10,3 mg/dL e 3,5 - 6,7 mg/dL, respectivamente. Os níveis de PTH não se associaram a sobrevida, mesmo quando dentro dos limites recomendados pelas duas diretrizes / INTRODUCTION: Mineral and bone disorders (MBD) contribute significantly to reduced survival of patients on dialysis. The main guidelines, Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease: Improving Global Outcomes (KDIGO), related to the subject, were based upon the mostly in articles involving hemodialysis patients. The aim of our study was to analyze calcium (Ca), phosphorus (P) and parathyroid hormone (PTH) as predictors of survival in the Brazilian Peritoneal Dialysis II (BRAZPDII) cohort. METHODS: We used the Brazilian Peritoneal Dialysis II (BRAZPDII) database, an observational multi-centric prospective study, which assessed patients on Peritoneal Dialysis (PD) between December 2004 and January 2011. Amongst 9,905 patients included in this base, we selected 844 who presented complete demographic, clinical and laboratory data as well as 6 months on PD. This group of patients was followed up for 24 months. The confounding variables were included in multivariate models (Cox and competing risk), serum levels of Ca, P and PTH were the variables of interest and associated with patients\' survival on PD. RESULTS: Ca and P presenting improvements association with relative hazard when the values close to 9.7 and 5.0 mg/dL, respectively. We found a significant association between the levels of calcium, categorized by KDIGO (Ca: 8.4 - 10.2 mg/dL), and survival (p = 0.03), likewise, a compelling association between levels of P, categorized by both guidelines (KDOQI and KDIGO - P: 3.5 - 5.5 mg/dL, p < 0.01). Other ranges of Ca, (8.6 - 10.3 mg/dL, p < 0.01) and P (3.5 - 6.7 mg/dL, p < 0.01), which were proposed in this study, have shown additional risk. In spite of patients with PTH levels close to 532 pg/mL show better survival, we found no significant statistical association values of PTH categorized according to both guidelines, KDOQI (150 - 300 pg/mL) and KDIGO (150 - 600 pg/mL). CONCLUSION: In conclusion, the ranges levels of Ca proposed by KDIGO and P proposed by the both guidelines, and based in hemodialysis patients studies, has improved survival also in patients on PD. Higher levels of Ca and P have shown additional risk. Despite PTH being in the limits recommended in both guidelines, they were not associated with survival

INTRODUÇÃO: Em pacientes transplantados renais, a paratireoidectomia está associada à piora aguda da função renal. Os efeitos agudos e crônicos da paratireoidectomia sobre a filtração glomerular foram pouco estudados em Hiperparatireoidismo Primário (HPTP). MÉTODO E CASUÍSTICA: Neste estudo retrospectivo de coorte, foram estudados 494 pacientes submetidos a paratireoidectomia por HPTP, entre os anos de 2007 e 2016. Variações agudas da creatinina foram aferidas diariamente na internação, até o 4o pós-operatório, sendo classificados conforme os critérios de KDIGO para IRA. Dados bioquímicos incluíram dosagem sérica de creatinina, cálcio iônico e total, paratormônio (PTH) e 25-OH vitamina D. A taxa de filtração glomerular foi estimada a partir da equação CKD-EPI. Foram comparados dados de função renal pré e pós-operatórios até 5 anos de seguimento. RESULTADOS: Dos 494 pacientes, 391 (79,1%) eram mulheres e 422 (85,4%) de cor branca. A causa mais comum de HPTP foi adenoma de paratireóide (351, 71,1%) e a mediana de idade foi de 58 anos. As medianas (Q1-Q3) de creatinina, PTH e cálcio total séricos foram de: 0,81 mg/dL (0,68-1,01), 154,5 pg/mL (106-238,5) e 10,9 mg/dL (10,3-11,5) respectivamente. A mediana de eGFR préoperatória foi de 86 mL/min x 1,73m2. No período agudo, houve redução mediana de 26 mL/min x 1,73m2 na eGFR (p < 0,0001), que representou -27,44% (±19,12%) de variação aguda da eGFR. De acordo com os critérios de IRA, 41,1% dos pacientes tiveram IRA estágio 1, 5,9% estágio 2 e 1,8% estágio 3. Outros 223 pacientes (45,1%) tiveram elevação da creatinina porém não preencheram critérios de IRA. Na análise univariada foram observadas correlações fracas, porém significativas, entre o percentual de variação aguda de eGFR e os seguintes fatores pré-operatórios: idade, PTH, cálcio e creatinina. Uma redução definitiva da eGFR foi observada em 60,7% dos pacientes, após 12 meses de seguimento. CONCLUSÃO: Houve significativa redução aguda da função renal após paratireoidectomia por HPTP, sendo que quase metade dos pacientes preencheram critérios de IRA. Observou-se importante recuperação da eGFR no primeiro mês de pós-operatório, podendo ocorrer algum grau de perda definitva de função renal / INTRODUCTION: In kidney transplant patients, parathyroidectomy is associated with acute decrease in renal function. Acute and chronic effects of parathyroidectomy on renal function have not been as extensively studied in primary hyperparathyroidism (PHPT). PATIENTS AND METHODS: Retrospective cohort study of 494 patients undergoing parathyroidectomy for PHPT. Acute renal changes were evaluated daily until day 4 post parathyroidectomy, and stratified according to acute kidney injury (AKI) criteria. Biochemical assessment included serum creatinine, total and ionized calcium, PTH, and 25-hydroxyvitamin D (25OHD). EGFR were calculated using the CKD-EPI equation. We compared preoperative and postoperative renal function up to 5 years of follow-up. RESULTS: 391 (79.1%) patients were female and 422 (85.4%) were non-African American. Median age was 58 years old. Median (interquartile range) preoperative serum creatinine, PTH and total calcium were 0.81 mg/dL (0.68- 1.01), 154.5 pg/mL (106-238.5), and 10.9 mg/dL (10.3-11.5) respectively. Median (interquartile range) preoperative eGFR was 86 mL/min/1.73m2 (65-101.3). After surgery the median acute decrease in eGFR was 26 mL/min/1.73m2 (p < 0.0001). Acutely, 41.1% patients developed AKI stage 1, 5.9% AKI stage 2 and 1.8% AKI stage 3. Acute eGFR decrease (%) correlated with age, PTH, calcium and preoperative creatinine, in univariate analysis. Permanent reduction in eGFR occurred in 60.7 % of the patients, after acute episode. CONCLUSION: There is a significant acute impairment in renal function after parathyroidectomy for PHPT and almost half of patients meet the criteria for AKI. Significant eGFR recovery was observed during first month after surgery, but a small permanent reduction may occur

Síndrome das pernas inquietas (SPI) é um distúrbio do sono com alta prevalência entre pacientes em hemodiálise, nos quais o mecanismo é pouco conhecido. Tem sido postulado que alterações do metabolismo mineral e ósseo relacionadasà doença renal crônica, especialmente o hiperparatireoidismo secundário, possam estar relacionadas à patogênese da SPI. Este trabalho teve como objetivo principal avaliar a SPI antes e após paratireoidectomia (PTX). Além disso, avaliamos dados objetivos do sono por meio de polissonografia, com ênfase em apneia do sono. Estudamos prospectivamente 19 pacientes (6 homens, idade 48 ± 11 anos) com hiperparatireoidismo grave pré e pós-PTX. O diagnóstico e o escore de gravidade da SPI foram avaliados de acordo com o Grupo de Estudo Internacional de SPI. Polissonografia pré e pós-PTX forneceu dados de arquitetura do sono, movimentos periódicos de pernas e apneia do sono, medida por meio do índice de apneia-hipopneia/hora de sono (IAH). SPI foi encontrada em 10 pacientes (53%) e se associou com maiores níveis de fosfato (p=0,005) e maior gravidade da dor (p=0,003). Após a PTX, houve redução dos níveis séricos de paratormônio, fosfato e aumento dos níveis de 25-hidroxivitamina D, calicreína-6 e fetuína-A. A PTX reduziu a SPI para 21% (p=0,044), acompanhada por redução nos escores de gravidade e alívio da dor e do prurido. A análise de regressão logística mostrou que o fosfato pré-PTX permaneceu independentemente associado com SPI (OR=7,28; p=0,035), em modelo ajustado para hemoglobina, idade e sexo. Apneia do sono (IAH > 5) foi encontrada em 11 pacientes pré e 14 pós-PTX (63% vs. 74%, p=0,698). Observamos uma correlação entre o IAH e a relação água corporal extracelular/massa magra (r=0,535, p=0,018), assim como correlação com a circunferência do pescoço pré-PTX (r=0,471, p=0,042). Entretanto, não observamos correlação do IAH com o deslocamento de fluidos da perna direita durante o sono (p=0,09), que aumentou significativamente após PTX (p=0,011). Concluímos que a PTX melhora a SPI, com cura completa ou melhora significativa. Se essa melhora está relacionada à diminuição do paratormônio ou do fósforo necessita de investigação adicional. Além disso, o presente estudo confirma a alta prevalência de apneia do sono entre pacientes em hemodiálise, o que não se modificou com a PTX / Restless legs syndrome (RLS) is a sleep disorder with high prevalence among patients on hemodialysis, which underlying mechanism is still unknown. It has been postulate that bone metabolism disorder, especially secondary hyperparathyroidism may be implicated in the pathogenesis. The present study aimed to evaluate RLS before and after parathyroidectomy (PTX). In addition, we evaluated objective data through polysomnography, focusing on sleep apnea. We prospectively evaluated 19 patients (6 men, aged 48 ± 11 years) with severe hyperparathyroidism pre and post-surgical treatment, parathyroidectomy (PTX). RLS diagnosis and rating scale were accessed based on the International RLS Study Group. Polysomnography pre and post PTX provided data on sleep architecture, periodic leg movements of sleep and apnea-hypopnea index (AHI). RLS was observed in 10 patients (53%), and was associated with higher levels of phosphate (p=0,005) and severe pain (p=0,003). After PTX, there was a reduction of serum parathyroid hormone, serum phosphate, and an increase of 25hydroxyvitamin D, kallicrein-6 and Fetuin-A. PTX improved RLS to 21% (p=0,04), accompanied by a decrease in rating scale, in association with alleviation of pain and pruritus. Logistic regression shows that serum phosphate pre PTX remained independently associated with RLS (HR=7,28; p=0,035), in a model adjusted for hemoglobin, age and gender. Sleep apnea (AHI > 5) was found in 11 patients pre and 14 patients post PTX (63% vs. 74%, p=0,698). There was a correlation between AHI and the relation extracellular water/ lean body mass (r=0,535; p=0,018) as well as a correlation between AHI and neck circumference (r=0,471; p=0,042). However, there was no correlation between AHI and spontaneous rostral fluid shift (p=0,09) that has increased after PTX (p=0,011). We concluded that PTX provided an opportunity to improve RLS. Whether RLS may be improved by reduction of serum phosphorus or parathyroid hormone, merits further investigation. In addition, PTX had no impact on the high prevalence of sleep apnea in this population

A doença cardiovascular (DCV) é a principal causa de mortalidade nos pacientes com doença renal crônica (DRC) e a hipertrofia de ventrículo esquerdo (HVE), a alteração mais freqüente. A remodelação cardíaca (RC) patológica ocorre em resposta a agressões como sobrecarga de volume ou de pressão e é influenciada por ativação neurohormonal, fatores locais, inflamação, isquemia, necrose e apoptose celular. Os miócitos são as principais células envolvidas na RC. Avaliamos o papel da hiperfosfatemia e do paratormônio (PTH) em animais urêmicos. Trinta e dois ratos Wistar machos foram submetidos à paratireoidectomia (PTX) e nefrectomia (Nx), com reposição contínua de PTH em concentração fisiológica (PTHf= 0,022 ug/100g/h) ou elevada (PTHe=0,11 ug/100g/h). Os animais sham (N=16) foram operados e recebiam infusão de veículo. Apenas o conteúdo de fósforo nas dietas era diferente, ou seja: pobre=0,2% (pP) ou rica em fósforo=1,2% (rP). Dividimos os animais em 6 grupos: Sham: Sham-pP (G1), Sham-rP (G2); PTX+Nx: PTHf-pP (G3), PTHf-rP (G4), PTHe-pP (G5), PTHe-rP (G6). Semanalmente determinamos o peso e a pressão arterial caudal. Creatinina, fósforo, cálcio PTH e hematócrito foram analisados. Após 8 semanas os animais foram sacrificados. A hipertrofia e fibrose miocárdicas foram analisadas com o sistema digital Leica. O peso do coração corrigido por 100g peso corporal foi maior nos grupos G5 e G6 e apresentou uma correlação positiva com hipertrofia e fibrose miocárdica. A hipertrofia e fibrose foram menores no G3, quando comparado aos grupos Nx. A hipertrofia miocárdica foi maior no G6, evidenciando o papel do P neste processo. A fibrose mocárdica ocorreu principalmente em subendocárdio e foi mais intensa no G6. Analisamos a expressão do fator transformador de crescimento (TGF-beta) e angiotensina II que foram mais intensas nos grupos G5 e G6. As lesões das artérias coronarianas foram avaliadas de forma semi-quantitativa e os animais G5 e G6 mostraram calcificações de camada média. A expressão da alfa-actina se correlacionou negativamente com as lesões coronarianas. Nossos resultados demonstraram a importância do fósforo e PTH na fisiopatologia da DCV, sendo necessário um melhor controle destes elementos para prevenção de mortalidade nos pacientes com DRC. / Cardiovascular disease (CVD) is the leading cause of mortality in patients with chronic kidney disease (CKD), and left ventricular hypertrophy (LVH) is the most common alteration. Pathologic cardiac remodeling (CR) occurs in response to injuries such as volume or pressure overload, and it is influenced by neurohormonal activation, local factors, inflammation, ischemia, necrosis and cellular apoptosis. Myocytes are the principal cells involved in CR. We evaluated the role of hyperphosphatemia and parathyroid hormone (PTH) in uremic animals. Thirty-two male Wistar rats were submitted to parathyroidectomy (PTX) and nephrectomy (Nx), with PTH continuous replacement in physiologic concentration (PTHf=0.022ug/100g/h) or elevated (PTHe=0.11ug/100g/h). The sham animals (N=16) were operated and received vehicle infusion. Only the phosphorus content in diets was different, that is: poor = 0.2% (pP) or rich in phosphorus = 1.2% (rP). We divided the animals into 6 groups: Sham: Sham-pP (G1), Sham-rP (G2); PTX+Nx: PTHf-pP (G3), PTHf-rP (G4), PTHe-pP (G5), PTHe-rP (G6). We determined the weight and caudal blood pressure weekly. Creatinine, phosphorus, PTH calcium and hematocrit were analyzed. After 8 weeks, the animals were sacrificed. Myocardial hypertrophy and fibrosis were analyzed using Leica digital system. The weight of the heart corrected for 100g body weight was greater in groups G5 and G6 and presented a positive correlation with myocardial hypertrophy and fibrosis. Hypertrophy and fibrosis were lower in G3, when compared to Nx groups. Myocardial hypertrophy was higher in G6, determining the role of P in this process. Myocardial fibrosis occurred mainly in subendocardium and was more intense in G6. We analyzed the expression of transforming growth factor (TGF-alfa) and angiotensin II, which were more intense in groups G5 and G6. Coronary artery lesions were evaluated semiquantitatively and G5 and G6 animals showed middle layer calcifications. Expression of alfa-actin correlated negatively with coronary lesions. Our results demonstrated the importance of phosphorus and PTH in the pathophysiology of CVD; therefore, a better control of these elements is required in order to prevent mortality in patients with CKD.

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.