Made available in DSpace on 2016-01-26T18:55:41Z (GMT). No. of bitstreams: 1 Yona Murad.pdf: 235020 bytes, checksum: 9b83ae7421537fd5e72802ad16c29b88 (MD5) Previous issue date: 2014-09-26 / In order to determine the hematologic changes resulting from the use of rhGH (recombinant human growth hormone), associated or not with physical training in rats, eighty Wistar rats, average weight of 211.8 g were randomly divided into four groups (n=20): CT (control group without physical training and without administration of rhGH), GH (group without physical training and with rhGH), TR (group with physical training and without rhGH) and TRGH (physical training group with rhGH). The animals in groups GH and TRGH received 0.2 IU/kg rhGH subcutaneously every two days during the 30 day period. Physical training was performed using a jumping protocol consisting of four sets of ten jumps with overload of 50% of body weight, three days a week, in a cylindrical container with 38 cm of heated water (30° C). At the end of 4 weeks, the animals were weighed, anesthetized and then killed by exsanguination for collection of blood for analyses. The following parameters were evaluated: number of erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, RDW (Red Cell Distribution Width), and leukocyte count. Red blood cell parameters did not change with exercise training and / or hormonal supplementation. In all groups RDW remained unchanged. The leukocyte count of the animals that have done physical training and were supplemented with hormone was higher when compared to sedentary rats (P < 0.05). The administration of rhGH at a dose of 0.2 IU/kg associated with exercise training increased the number of leukocytes, but did not change the remaining parameters of the hemogram in sedentary and active rats. It was not possible to detect an increase in erythropoiesis, through the use of rhGH, using these variables. / Com o objetivo de verificar as alterações hematológicas decorrentes do uso do rhGH (hormônio do crescimento recombinante humano), associado ou não ao treinamento físico, foram utilizados 80 ratos da linhagem Wistar, peso médio de 211,8 g que foram distribuídos aleatoriamente em quatro grupos (n=20): CT (grupo controle sem treinamento físico e sem administração de rhGH), GH (grupo sem treinamento físico e com rhGH), TR (grupo com treinamento físico e sem rhGH) e TRGH (grupo com treinamento físico e com rhGH). Os animais dos grupos GH e TRGH receberam 0,2 UI/kg de rhGH por via subcutânea a cada dois dias durante o período de 30 dias. O treinamento físico foi realizado por meio de protocolo de salto composto de quatro séries de dez saltos, com sobrecarga de 50% do peso corpóreo, durante três dias na semana, em um recipiente cilíndrico com 38 cm de água aquecida (30°C) em seu interior. Ao final de 4 semanas, os animais foram pesados, anestesiados e então mortos por exsanguinação para colheita do sangue para a realização do hemograma. Foram avaliados os seguintes parâmetros: número de eritrócitos, hemoglobina, hematócrito, volume corpuscular médio, concentração de hemoglobina corpuscular média, RDW (Red Cell Distribution Width) e contagem de leucócitos totais. As variáveis do eritrograma não sofreram alterações com o treinamento físico e/ou suplementação hormonal. Em todos os grupos, os valores de RDW permaneceram inalterados. A contagem de leucócitos dos animais que fizeram treinamento físico e foram suplementados com hormônio foi maior quando comparados aos sedentários (P<0,05). Conclui-se que a administração do rhGH na dose de 0,2 UI/kg associado ao treinamento físico induziu a leucocitose, porém não influenciou os parâmetros da série vermelha tanto em animais sedentários como ativos. Não foi possível, a partir destas variáveis, detectar estímulo na eritropoiese destes animais.

Made available in DSpace on 2016-07-18T17:53:13Z (GMT). No. of bitstreams: 1 Yona Murad.pdf: 235020 bytes, checksum: 9b83ae7421537fd5e72802ad16c29b88 (MD5) Previous issue date: 2014-09-26 / In order to determine the hematologic changes resulting from the use of rhGH (recombinant human growth hormone), associated or not with physical training in rats, eighty Wistar rats, average weight of 211.8 g were randomly divided into four groups (n=20): CT (control group without physical training and without administration of rhGH), GH (group without physical training and with rhGH), TR (group with physical training and without rhGH) and TRGH (physical training group with rhGH). The animals in groups GH and TRGH received 0.2 IU/kg rhGH subcutaneously every two days during the 30 day period. Physical training was performed using a jumping protocol consisting of four sets of ten jumps with overload of 50% of body weight, three days a week, in a cylindrical container with 38 cm of heated water (30° C). At the end of 4 weeks, the animals were weighed, anesthetized and then killed by exsanguination for collection of blood for analyses. The following parameters were evaluated: number of erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, RDW (Red Cell Distribution Width), and leukocyte count. Red blood cell parameters did not change with exercise training and / or hormonal supplementation. In all groups RDW remained unchanged. The leukocyte count of the animals that have done physical training and were supplemented with hormone was higher when compared to sedentary rats (P < 0.05). The administration of rhGH at a dose of 0.2 IU/kg associated with exercise training increased the number of leukocytes, but did not change the remaining parameters of the hemogram in sedentary and active rats. It was not possible to detect an increase in erythropoiesis, through the use of rhGH, using these variables. / Com o objetivo de verificar as alterações hematológicas decorrentes do uso do rhGH (hormônio do crescimento recombinante humano), associado ou não ao treinamento físico, foram utilizados 80 ratos da linhagem Wistar, peso médio de 211,8 g que foram distribuídos aleatoriamente em quatro grupos (n=20): CT (grupo controle sem treinamento físico e sem administração de rhGH), GH (grupo sem treinamento físico e com rhGH), TR (grupo com treinamento físico e sem rhGH) e TRGH (grupo com treinamento físico e com rhGH). Os animais dos grupos GH e TRGH receberam 0,2 UI/kg de rhGH por via subcutânea a cada dois dias durante o período de 30 dias. O treinamento físico foi realizado por meio de protocolo de salto composto de quatro séries de dez saltos, com sobrecarga de 50% do peso corpóreo, durante três dias na semana, em um recipiente cilíndrico com 38 cm de água aquecida (30°C) em seu interior. Ao final de 4 semanas, os animais foram pesados, anestesiados e então mortos por exsanguinação para colheita do sangue para a realização do hemograma. Foram avaliados os seguintes parâmetros: número de eritrócitos, hemoglobina, hematócrito, volume corpuscular médio, concentração de hemoglobina corpuscular média, RDW (Red Cell Distribution Width) e contagem de leucócitos totais. As variáveis do eritrograma não sofreram alterações com o treinamento físico e/ou suplementação hormonal. Em todos os grupos, os valores de RDW permaneceram inalterados. A contagem de leucócitos dos animais que fizeram treinamento físico e foram suplementados com hormônio foi maior quando comparados aos sedentários (P<0,05). Conclui-se que a administração do rhGH na dose de 0,2 UI/kg associado ao treinamento físico induziu a leucocitose, porém não influenciou os parâmetros da série vermelha tanto em animais sedentários como ativos. Não foi possível, a partir destas variáveis, detectar estímulo na eritropoiese destes animais.

Haematopoietic stem and progenitor cells (HSPCs) are crucial for lifelong blood cell production. We analysed the cell cycle and cell production rate in HSPCs in murine haematopoiesis. The labelling of DNA-synthesizing cells by two thymidine analogues, optimized for in-vivo use, enabled the determination of the cell cycle flow rate into the G2-phase, the duration of the S-phase and the average cell cycle time in Sca-1+ and Sca-1- HSPCs. The determination of cells with 2n DNA content and labelled during the preceding S-phase was used to establish the cell flow rates in the G1-phase. Our measurements revealed a significant difference in how Sca-1+ and Sca-1- HSPCs self-renew and differentiate. The division of Sca-1+ progenitors led to the loss of the Sca-1 marker in about half of newly produced cells, corresponding to asymmetric cell division. In contrast both Sca-1- progenitors, arising from mitotic cell division, entered a new round of the cell cycle. This corresponds to symmetric self-renewing cell division. The novel data also enabled us to estimate the cell production rates in the Sca-1+ and in three subtypes of Sca-1- HSPCs. We focused on adult murine erythroid differentiation in the next part of our study. We introduced an original flow cytometry approach for identifying and studying erythroid...

Hematopoiesis is a precisely regulated process, dependent on the activity of hematopoietic cytokines and their receptors. Due to an extra round of whole genome duplication in teleost fish, two paralogs of many important genes, including some hematopoietic cytokines and their receptors, are present in the zebrafish (Danio rerio) genome. In this project, we have been investigating the role of zebrafish Kit ligands in hematopoiesis. Kit ligand is a pleiotropic cytokine, which is essential for vertebrate erythropoiesis; however, in zebrafish, no such role has been reported so far. To determine the function of zebrafish paralogs of Kit ligand (Kitlga and Kitlgb) in hematopoiesis, we performed in vivo and ex vivo gain- and loss-of-function experiments. Strikingly, we were the first to report the synergistic cooperation of zebrafish Kitlga with erythropoietin and dexamethasone, enabling the growth of kidney marrow-derived suspension cells and providing optimal conditions for the expansion of adult erythroid progenitors. We assume that by using different cytokine combinations, optimal conditions for the growth of other hematopoietic cell types can be established, and therefore, this new approach now available for the...

In the mammalian genome, 5‟-CpG-3‟ dinucleotides are frequently methylated, correlating with transcriptional silencing. Genome-wide waves of demethylation are thought to occur only twice during development, in primordial germ cells and in the pre-implantation embryo. They are followed by de novo methylation, setting up a pattern that is inherited throughout development. No global methylation changes are thought to occur during further somatic development, although methylation does alter at gene-specific loci, contributing to tissue-specific patterns of gene expression. Here we studied DNA methylation in differentiating mouse erythroblasts in vivo using several approaches including genomic-scale, reduced representation bisulfite sequencing (RRBS). Surprisingly, demethylation at the erythroid-specific β-globin locus was coincident with a wave of global DNA demethylation at most genomic elements, including repetitive elements and genes silenced in erythropoiesis. Over 30% of total methylation is irreversibly lost during erythroid differentiation. Demethylation occurred through a passive mechanism, requiring the rapid DNA replication triggered with the onset of erythroid terminal differentiation. Global loss of DNA methylation was not associated with a global increase in transcription, as determined by GeneChip analysis. We propose that global demethylation is a consequence of cellular mechanisms required for the rapid demethylation and induction of β-globin and other erythroid genes. Our findings demonstrate that, contrary to previously held dogma, DNA demethylation can occur globally during somatic cell differentiation, providing a new experimental model for the study of global demethylation in development and disease.

Background: FDA black box warning, Risk Evaluation and Mitigation Strategies (REMS), and CMS national coverage determination (NCD) aim to reduce inappropriate use of erythropoiesis-stimulating agents (ESAs) that are widely used in anemic patients. Previous studies have not linked specific safety interventions to changes in ESA utilization patterns in the inpatient settings nor assessed such interventions on off-label use of the drugs. Ineffectiveness of the intervention and lag time between such interventions and the observed change in clinical practice could lead to serious clinical outcomes. In addition, such interventions may unintentionally reduce on-label and some off-label use of ESAs considered “appropriate” in patients who could otherwise benefit. Objectives: The primary aim of the study is to quantify the impacts of the (1) addition of black box warning, (2) implementation of NCD, and (3) institution of REMS on ESA on-label and off-label utilization patterns of adult inpatients. Demographic, clinical condition, physician, and hospital characteristics of ESAs users by their use category are also described in detail. Methods: Electronic health records in Cerner Database from January 1, 2005 to June 30, 2011 were used. The use of the two erythropoietic drugs: epoetin alfa and darbepoetin alfa were categorized into three groups using ICD-9-CM diagnoses and procedures codes and patients’ medication information. The three categories were (1) on-label use (approved by the FDA); (2) off-label use supported (use for the indications not approved by the FDA, but there is strong clinical evidence to support its use); and (3) off-label use unsupported (use for the indications not approved by the FDA and lacking clinical evidence). The immediate and trend impacts of the interventions on the proportion of ESAs prescribed for each usage category between 2005 and 2011 were assessed using an interrupted time series technique. The likelihood of receiving ESAs among patients with on-label, off-label supported, off-label unsupported indications was assessed using a generalized estimating equation approach with binary logistic regression technique, clustering for hospitals and controlling for potential confounders such as patient characteristics, patient clinical conditions, physician specialty, and hospital characteristics. Results: During the study period, there were 111,363 encounters of ESA use. These encounters represented 86,763 patients admitted to Cerner health system between January 1, 2005 and June 30, 2011. Of these patients, 66,121 were prescribed epoetin alfa only (76.2%); 20,088 darbepoetin alfa only (23.2%); and 554 were prescribed both epoetin alfa and darbepoetin alfa (0.6%). Forty-nine percent of the patients used ESAs for the on-label indications, 8.6% for off-label supported indications, and 42.7% for the off-label unsupported indications. The main uses of ESAs in our sample were for CKD (ONS, 41.1%) and chronic anemia (OFU, 31.8%). From 2005 to 2010, the proportion of visits with ESA ONS and OFS use decreased 53.2% and 81.9%, while ESA OFU increased 112.6%. Results from binary logistic regression using GEE model showed overall decreasing trends in ESA use for the on-label and off-label supported indications, but not off-label unsupported indications. REMS had no impact on the odds of receiving ESAs among patients with on-label and off-label conditions. Black box warning reduced the odds of being prescribed with epoetin alfa in patients with off-label unsupported conditions by 40%. It was also associated with 4% and 15% per month reduction in the odds of using darbepoetin alfa in patients with off-label supported and unsupported conditions. Lastly, there was a significant decline in all categories of ESA use the month after Medicare national coverage determination was implemented. The impact of NCD ranged from a 20% reduction in the odds of off-label supported use to a 37% reduction in on-label use. Age, gender, race, source of payment, admission type, clinical complexity, discharge disposition, and hospital size were significant associated with ESA use on-label and off-label. Conclusion: This study was the first to determine the impact of safety interventions on ESA on-label and off-label utilization patterns in the inpatient settings using the Cerner database. We demonstrated lag between the interventions and observed change in clinical practice, and the relative impacts of three types of safety interventions on on-label and off-label ESA use in the hospital settings. The indirect impact of the reimbursement change was the potential unintended consequence of reducing the likelihood of receiving ESAs for a patient with indicated conditions who could have otherwise benefited from the drugs.

L’anémie de Blackfan-Diamond (ABD) est une maladie hématologique rare qui touche 4 à 7 individus/ million de naissances. Cette maladie se manifeste par une érythroblastopénie congénitale sévère (≤ 5% de précurseurs érythroïdes dans la moelle osseuse). L’anémie est arégénérative et souvent macrocytaire et associée à des malformations osseuses dans 40% des cas. 70% des patients sont porteurs d’une mutation hétérozygote pour un gène de protéine ribosomique impliquée dans la traduction cellulaire. Les gènes les plus fréquemment mutés sont les gènes RPS19 (25%), RPL11 (5%) et RPL5 (7%). La maladie est hétérogène et évolutive. Les liens entre la traduction cellulaire et l’érythropoïèse ne sont pas bien élucidés. Les objectifs de cette thèse ont été d’étudier les métabolismes de l’hème et du fer ainsi que l’expression des globines dans des cellules de patients atteints d'ABD et dans un modèle shARN ciblant l'expression de ces trois gènes afin de comprendre les causes du tropisme érythroïde de la maladie. Ce travail de recherche a permis de mettre en évidence un défaut majeur de synthèse des globines ayant pour conséquence une augmentation de la quantité d’hème libre et une production de formes réactives de l'oxygène toxiques dans les cellules des patients qui pourraient expliquer en partie l’apoptose cellulaire et le déficit de globules rouges. Alors que le métabolisme du fer ne semblait pas altéré dans l'ABD, l’étude de l’expression de différentes protéines importantes pour l’érythropoïèse au cours de la différenciation érythroïde in vitro dans des conditions contrôles et chez des patients a permis de confirmer et de caractériser le retard de différenciation cellulaire en cas de mutation des gènes RPL5 et RPL11. Ce travail montre que le retard de différenciation et le défaut d'hémoglobinisation mis en évidence s'expliquent par un déficit du facteur de transcription GATA-1 qui est primordial au cours de l'érythropoïèse. Ce déficit de GATA-1 dans des cellules déficitaires en RPL11 est dû à une dégradation de sa protéine chaperonne HSP70. La restauration de HSP70, permet d'augmenter l'expression de GATA-1 et d'améliorer la différenciation érythroïde et l'hémoglobinisation cellulaire pour le gène RPL11. Ces résultats permettent de mieux comprendre le tropisme érythroïde de l'ABD et de proposer HSP70 comme une cible thérapeutique prometteuse dans son traitement. / Diamond-Blackfan anemia (DBA) is a rare hematologic disease that affects 4 to 7 individuals / million births. This disease is characterized by a severe congenital erythroblastopenia (less than 5% erythroid precursors in the bone marrow). Anemia is agerenative, often macrocytic and associated with bone malformations in 40% of cases. 70% of patients carry a heterozygous mutation for a ribosomal protein gene involved in cell translation. The most frequently mutated genes are RPS19 (25%), RPL11 (5%) and RPL5 (7%) genes. The disease is heterogeneous and can evolve. The link between cell translation and erythropoiesis is not well understood. The objectives of this thesis were to study haem and iron metabolisms as well as the expression of globins in DBA patients cells and CD34+ cells transduced with shRNA targeting the expression of these three genes in order to understand the causes of the erythroid tropism of the disease. This research has highlighted a major defect of globin synthesis resulting in an increase in the amount of free heme and a production of toxic ROS in patients' cells that could explain in part cell apoptosis and red blood cell deficiency. While iron metabolism did not appear to be altered in DBA, the study of the expression of various important proteins for erythropoiesis in normal CD34+ or DBA cells during erythroid differentiation in vitro confirmed a strong cell differentiation delay for RPL5 and RPL11 mutations. This work shows that the delay of differentiation and the lack of hemoglobinization can be explained by a deficiency of the transcription factor GATA-1, which is essential during erythropoiesis. This deficiency of GATA-1 in shRPL11 cells is due to a degradation of its chaperone protein HSP70. The restoration of HSP70 increases the expression of GATA-1 and improves erythroid differentiation and cellular hemoglobinization for the shRPL11 condition. These results provide a better understanding of the erythroid tropism of ABD and suggest a role for HSP70 as a promising therapeutic target in its treatment.

As síndromes talassêmicas (?- e ?-talassemia) são as desordens mais comuns e frequentes associadas com eritropoese ineficaz. O desbalanço na produção das cadeias ?- e ?-globinas resulta no comprometimento da produção de eritrócitos, em anemia e aumento de progenitores eritroides no sangue periférico. Enquanto os pacientes homozigóticos afetados por essas desordens demonstram alterações características dos parâmetros relacionados a eritropoese, a relação entre grau de anemia, eritropoese alterada e disfunção do metabolismo de ferro ainda não foram investigados nos indivíduos com ?+-talassemia heterozigótica ou ?+-talassêmia. Duzentos e vinte seis indivíduos (75 do gênero feminino e 151 do gênero masculino) foram recrutados e divididos em 5 grupos: Controle (n=28), doadores de sangue regulares (DSR, n=23), ?+-talassemia heterozigótica (TAT, n=14), ?+-thalassemia (traço ?-talassêmico, TBT, n=20) e ?0-talassemia, (?-talassemia maior, BTM, n=27). As amostras foram analisadas para parâmetros hematológicos (Micros ABX 60); ferro sérico, capacidade total de ligação ao ferro e saturação de transferrina por método colorimétrico (Pointe Scientific, Inc., Canton, MI, USA), ferritina e proteína C-reativa ultra sensível por imunoensaio (Immulite 1000); receptor solúvel de transferrina, eritropoetina, fator de diferenciação do crescimento 15 (R&D Systems) e hepcidina (Intrinsic LifeSciences, La Jolla, CA) por ELISA. As razões sTfR/log ferritina e (hepcidina/ferritina)/sTfR foram calculadas para avaliar o metabolismo do ferro. sTfR/log ferritina pode distinguir depleção dos estoques de ferro de eritropoese deficiente de ferro, enquanto (hepcidina/ferritina)/sTfR pode avaliar os estímulos contrários (disponibilidade de ferro e atividade eritropoética) que controlam a síntese de hepcidina e a absorção de ferro, na ausência de estímulos inflamatórios. Foi demonstrado que TAT teve significativa redução da hepcidina e aumento do receptor solúvel de transferrina, com parâmetros hematológicos relativamente normais. Em contraste, todos os parâmetros hematológicos de TBT foram significativamente diferentes do Controle, incluindo aumento dos níveis do receptor solúvel de transferrina, ferritina, eritropoetina e fator de diferenciação do crescimento 15. Essas alterações em ambos os grupos sugerem um balanço alterado entre eritropoese e metabolismo de ferro. Os índices sTfR/log ferritina e (hepcidina/ferritina)/sTfR estão, respectivamente, aumentado e reduzido comparados ao Controle, proporcional a severidade de cada grupo talassêmico. Em conclusão, destacamos que, pela primeira vez, foram descritas alterações no metabolismo de ferro em indivíduos com ?+-talassemia heterozigótica. Esses dados demonstram que, no contexto da saúde pública, são necessários identificação e acompanhamento dos portadores de ?+-talassemia. / The thalassemia syndromes (?- and ?-thalassemia) are the most common and frequent disorders associated with ineffective erythropoiesis. Imbalance of ?- or ?-globin chain production results in impaired red blood cell synthesis, anemia and more erythroid progenitors in the blood stream. While patients affected by these disorders show definitive altered parameters related to erythropoiesis, the relationship between the degree of anemia, altered erythropoiesis and dysfunctional iron metabolism have not been investigated in both carriers of ?-thalassemia and ?-thalassemia. 226 subjects (75 females and 151 males) were recruited to this study and divided in 5 groups: Control (n=28), repeat blood donors (DSR, n=23), ?+-thalassemia heterozygous carriers (TAT, n=14), ?+-thalassemia (?-thalassemia trait, TBT, n=20) and ?0-thalassemia, (?-thalassemia major, BTM, n=27). Samples were tested for hematological parameters (Micros ABX 60); serum iron, total iron binding capacity, and transferrin saturation by the colorimetric method (Pointe Scientific, Inc., Canton, MI, USA), ferritin and high sensitive C-reactive protein by immunoassay (Immulite 1000); soluble transferrin receptor, erythropoietin and growth differentiation factor 15 (R&D Systems) and hepcidin (Intrinsic LifeSciences, La Jolla, CA) by ELISA. Were calculated the ratios sTfR/log ferritin and (hepcidin/ferritin)/sTfR to evaluate iron metabolism. sTfR/log ferritin can distinguish storage iron depletion from iron-deficient erythropoiesis, while (hepcidin/ferritin)/sTfR can be utilized to explore and quantify the opposing forces (i.e. iron availability and erythropoietic activity) regulating hepcidin synthesis and iron absorption in absence of inflammatory stimuli. We demonstrate that TAT have a significantly reduced hepcidin and increased soluble transferrin receptor levels but relatively normal hematological findings. In contrast, TBT have all hematological parameters significantly different from controls, including increased soluble transferrin receptor, ferritin, erythropoietin and growth differentiation factor 15 levels. These changings in both groups suggest an altered balance between erythropoiesis and iron metabolism. The indexes sTfR/log ferritin and (hepcidin/ferritin)/sTfR are respectively increased and reduced relative to controls, proportional to the severity of each thalassemia group. In conclusion, we emphasize that, for the first time in the literature, subjects with heterozygous ?+-thalassemia have altered iron metabolism. Our data demonstrate that within the context of public health, identification and monitoring of patients with ?+-thalassemia are needed.

A síndrome de emagrecimento progressivo (SEP) é responsável por elevada morbidade e mortalidade de calitriquídeos mantidos em cativeiro em diferentes instituições. Essa síndrome representa um desafio aos médicos veterinários por suas características ainda pouco esclarecidas e são poucos os estudos multidisciplinares que visam à avaliação dos diferentes sistemas, como os órgãos linfo-hematopoiéticos. O objetivo foi caracterizar a evolução e duração da SEP, associando os dados clínicos, laboratoriais e anatomopatológicos dos órgãos linfo-hematopoiéticos de saguis naturalmente acometidos por SEP no cativeiro. Foram analisadas as fichas clínicas, necroscópicas e os resultados das amostras de sangue e urina de 47 saguis doentes, Callithrix spp., machos e fêmeas, que foram a óbito devido a SEP e eram provenientes de dois criadouros diferentes do estado de São Paulo. Os fragmentos dos órgãos linfo-hematopoiéticos, intestino delgado e do fígado foram processados e avaliados. Os resultados caracterizaram que a SEP acomete calitriquídeos de espécies diferentes, adultos, sem predisposição sexual, mantidos sob condições estáveis de manejo por em média 42 meses e a duração clínica varia de 41 dias a 1 ano e 7 meses. As características clínicas na fase inicial foram predominantemente sinais gastrintestinais e na fase terminal, sinais gastrintestinais e extra-intestinais. A anemia macrocítica normo ou hipocrômica com policromasia, esferocitose, presença de corpúsculos de Heinz e hemoglobinúria foi a alteração hematológica mais frequente. As lesões dos órgãos linfo-hematopoiéticos foram características de anemia hemolítica ou foram inespecíficas e reacionais caracterizadas por hiperplasia ou depleção das células da medula óssea, baço e linfonodo e lesões degenerativas no fígado. Na SEP, a associação clínica, laboratorial e anatomopatológica possibilitou a caracterização da evolução e duração clínica, da anemia e das alterações dos órgãos linfo-hematopoiéticos, cujas lesões foram consideradas secundárias à desnutrição crônica e progressiva decorrente da severa enterite atrófica. / Wasting marmoset syndrome (WMS) causes high morbidity and mortality of marmosets and tamarins kept in captivity in different colonies. WMS challenges the veterinarian due to its unclear and not established features and there are few multidisciplinary studies that carried out an evaluation of different systems, such the lymphohematopoietic system. The aim was described the duration and evolution of illness based on an association of clinical, laboratory and pathological aspects of WMS. Medical record, laboratory data and pathological findings were analyzed of 47 Callithrix spp., males and females, sick marmosets that died due to WMS in two different colonies in São Paulo state. Tissue samples of small intestine, lymphohematopoietc system and liver were histological processed and evaluated. The results showed that WMS affects adult marmosets of different species; there are no sex-related differences, and the marmosets are at least 42 months under similar general management at colony. The clinical duration of WMS is from 41 days to 1 year and 7 months. The clinical features were gastrointestinal symptoms in the beginning and extra-gastrointestinal and gastrointestinal signs in the end. Normochromic or hypochromic macrocytic anemia with polychromasia, spherocytes, Heinz bodies, and hemoglobinuria is the common hematological result. The lymphohematopoietic system lesions were the common findings of hemolytic anemia or unspecific and reacting features such as hyperplasia or depletion of cell numbers of bone marrow, spleen and lymph node, and degenerative lesions of liver. The clinical, laboratory and pathological association allowed the characterization of evolution and duration of the WMS, the anemia and the lesions of lymphohematopoietic organs which lesions were considered secondary to chronic and progressive malnutrition as a result of severe atrophic.

L’érythropoïèse est le processus de formation des globules rouges. L’anémie demeure à l’heure actuelle un problème de santé publique majeur. Par conséquent, une meilleure compréhension des mécanismes impliqués dans le contrôle de ce processus dans des conditions physiologiques et pathologiques, ainsi que l’établissement de stratégies thérapeutiques ciblées constituent un enjeu de recherche majeur. Le récepteur de la transferrine 1 (CD71/RTf1) est un élément essentiel de l'érythropoïèse, la majorité des travaux de recherche étant focalisés sur son rôle indéniable dans le métabolisme du fer. Cependant, de nouveaux ligands du RTf1 ont été découverts ouvrant de nouvelles perspectives relatives aux fonctionnalités de ce récepteur. Ayant démontré que le RTf1 fixait les immunoglobulines A1 (IgA1), nous nous sommes intéressés au rôle des IgA1 dans l’érythropoïèse. Nous montrons que le RTf1 lié aux polymères d'IgA1 (pIgA1) induit la croissance et une augmentation de la prolifération des érythroblastes en concentration sous-optimale d'érythropoïétine (Epo). De même, l'expression transgénique d’IgA1 humaine (souris alpha1-KI), ou le traitement de souris de type sauvage avec les pIgA1 permettent une récupération accélérée de l’anémie aiguë. L’engagement du RTf1 module la sensibilité à l'Epo, en diminuant le seuil d'activation cellulaire, et en induisant les voies de signalisation MAPK/ERK et phosphatidylinositol-3-kinase (PI3K/AKT). Ces données mettent en évidence un nouveau rôle du RTf1 en tant que régulateur positif de l'érythropoïèse. Parallèlement au RTf1, nous avons identifié un autre récepteur pouvant constituer une cible thérapeutique pour corriger une érythropoïèse inefficace : le récepteur de l’activine de type IIA (ActRIIA). Dans un modèle murin de Beta-thalassémie intermédiaire (Hbbth1/th1), résultant d'une déficience génétique de la chaîne Beta de la globine, nous montrons que l'administration d'une protéine de fusion constituée du domaine extracellulaire de l’ActRIIA lié à un fragment Fc d’IgG de souris (RAP-011), corrige l'anémie, augmente le taux d'hémoglobine et diminue la splénomégalie. Ce traitement favorise l’érythropoïèse splénique et diminue la saturation de la transferrine et l’hémolyse. Fait intéressant, des niveaux élevés de GDF11 (Growth Differentiation Factor 11) sont observés sur des coupes spléniques de souris thalassémiques ainsi que dans le sérum de patients thalassémiques. In vivo, l’inhibition de l’interaction GDF11/ActRIIa par le RAP-011 favorise l’apoptose des érythroblastes précoces par la voie Fas/FasLigand. Ces résultats suggèrent que l’activation constitutive des signaux GDF11/ActRIIA contribue à l’établissement d’une érythropoïèse inefficace caractéristique de la Beta-thalassémie. La neutralisation de cette signalisation inverse ce processus. En conclusion, nos travaux ouvrent de nouvelles perspectives dans la compréhension de l'hématopoïèse normale et pathologique, et pourraient conduire à envisager des traitements innovants pour l'anémie. / Anemia produced by a variety of underlying causes is the most common disorder of the blood, and remains a major global public health problem associated with a poor quality of life for many patients. Thus, better understanding the erythroid process in physiological and pathological conditions, and developing new strategies to boost erythropoiesis appear of great interest. Transferrin receptor 1 (CD71/TfR1) plays an essential role in erythropoiesis, and investigations of TfR1 functions have been focused on their undeniable role in iron metabolism. However, recent data demonstrate that TfR1 is a multi-ligand receptor that participates in a wide array of cellular functions. We have identified TfR1 as a receptor for A1 isotype immunoglobulins (IgA1). In this work, we show that pIgA1s are able through their interaction with the TfR1, to stimulate erythropoiesis by sensitizing erythroblasts to Epo. Likewise, transgenic expression of human IgA1 (Alpha1-KI mice) or treatment of wild-type mice with pIgA1 accelerated recovery from acute anemia. TfR1 engagement by pIgA1 increased cell sensitivity to Epo by inducing activation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. These findings unveiled a new role of TfR1 as a signaling competent molecule positively regulating erythropoiesis. In addition to TfR1, our work identifies another receptor as a putative target for correcting ineffective erythropoiesis: the activin receptor IIA (ActRIIA). Indeed, using a mouse model of Beta-thalassemia intermedia (Hbbth1/th1) resulting from a genetic deficiency of Beta-globin chain, we show that administration of a ligand trap (named RAP-011), consisting in a fusion protein between the extracellular domain of ActRIIA and the Fc fragment of a mouse IgG, improves anemia, increases total hemoglobin levels and decreases splenomegaly. In addition, targeting ActRIIa signaling corrects ineffective erythropoiesis in the spleen, reduces hemolysis and transferrin saturation. Interestingly, high levels of Growth Differentiation Factor 11 (GDF11) are detected in spleen sections from Beta-thalassemic mice, as well as in sera from thalassemic patients. In addition, the inactivation of GDF11 promotes terminal erythroblast differentiation. Finally, blockade of the GDF11/ActRIIa signaling, promotes premature apoptosis of early erythroblasts through induction of Fas/FasLigand pathway. Therefore, these results first suggest that constitutive GDF11/ActRIIa signaling pathway may promote ineffective erythropoiesis in Beta-thalassemia intermedia, and secondly, support the use of ActRIIa traps for the treatment of chronic anemia and ineffective erythropoiesis. Altogether, these results open new perspectives in the understanding of normal and pathological hematopoiesis and lead to propose innovative treatments for anemia.