La dimérisation des récepteurs couplés aux protéines G est un nouveau concept apparu dans la littérature au cours des quelques années qui ont précédé le début de notre travail. Bien qu’il soit clairement établi que les récepteurs sont capables de former des homo et des hétérodimères, les conséquences fonctionnelles de telles interactions demeurent souvent peu claires. Dans une étude précédente, le laboratoire d’accueil a montré que les récepteurs aux chimiokines CCR2 et CCR5 forment des homo et des hétérodimères de manière constitutive et identifié une coopérativité négative de liaison de nature allostérique entre les deux sites de liaison de CCR2 et CCR5 dans des cellules co-exprimant les deux récepteurs. Dans ce travail, nous avons étendu cette étude au récepteur CXCR4, structurellement plus éloigné que CCR2 et CCR5 entre eux. Nous montrons par une méthode biophysique se basant sur le transfert d’énergie de bioluminescence (le BRET) que CCR2, CCR5 et CXCR4 forment des homodimères et des hétérodimères de manière constitutive. De plus nous démontrons une coopérativité négative de liaison de nature allostérique des deux sites de liaisons pour les hétérodimères CCR2/CXCR4 et CCR5/CXCR4. lorsque CXCR4 est co-exprimé avec CCR2 ou CCR5, la chimiokine spécifique de CXCR4 (SDF-1α) inhibe la liaison du traceur spécifique de CCR2 (MCP-1) ou du traceur spécifique de CCR5 (MIP-1β), et vice-versa. La nature allostérique de ces interactions est démontrée par des expériences mesurant la dissociation de traceurs en présence ou non de compétiteurs. La coopérativité négative de liaison de nature allostérique des deux sites de liaisons est montrée également dans des cellules primaires, excluant tout effet indésirable dû à la surexpression de récepteurs. Nous montrons également que l’antagoniste spécifique de CXCR4 (AMD3100) inhibe la liaison du traceur spécifique de CCR2 (MCP-1) ou du traceur spécifique de CCR5 (MIP-1β), et vice-versa (TAK-779 vs SDF-1α), uniquement quand CXCR4 est co-exprimé respectivement avec CCR2 ou CCR5. Il s’agit là de la première preuve montrant que les interactions allostériques au sein d’hétérodimères de récepteurs aux chimiokines impliquent aussi des antagonistes, et qu’un antagoniste de récepteur aux chimiokines influence la réponse fonctionnelle d’un autre récepteur aux chimiokines auquel il ne se lie pas. De tels effets fonctionnels ont été montré dans des expériences de mobilisation de Ca++, de chimiotactisme sur lymphoblastes et dans des expériences d’air pouch in vivo.

Yersinia pestis, the infective agent of bubonic and pneumonic plague, is classified as a category A agent of bioterrorism. YopM, a protein toxin of Y. pestis, is necessary for full virulence in a systemic plague mouse model with ambient-temperature grown bacteria. We used this model to identify the cells undermined by YopM. Natural killer (NK) cells were previously reported to be lost in spleen and blood in a YopM-associated way; however, NK cell depletion was found not to occur in liver, and ablation of NK cells had no effect on bacterial growth, indicating that NK cells are redundant for the YopM-mediated virulence mechanism. In mice either ablated for Gr1+ cells or lacking the chemokine receptor CCR2, wildtype growth was at least partially restored to the ΔyopM Y. pestis in both spleen and liver. In a mouse model of bubonic plague, CCR2 also was shown to be required for the ΔyopM Y. pestis to show wildtype growth in skin. These data pointed towards Gr1+CCR2+ cells, which include polymorphonuclear leukocytes (PMNs), inflammatory monocytes and inflammatory dendritic cells (iDCs), as key cellular components in controlling the in vivo growth of the ΔyopM Y. pestis. Recruitment of Gr1+CCR2+ cells into both organs was not YopM-dependent, except iDCs, whose influx from blood into spleen was blocked by the YopM-producing Y. pestis parent strain, but not the ΔyopM mutant. Ablation of PMNs, another main subset of Gr1+CCR2+ cells, relieved the growth limitation of the ΔyopM Y. pestis in liver, but not in spleen. Taken together, the data imply that YopM disables the recruitment of CCR2+Gr1+ iDCs into spleen but compromises the function of CCR2+Gr1+ PMNs in liver. These results were recapitulated when the infecting ambient-temperature-grown bacteria received 3 hours of incubation at 37°C. However, the appearance of the ΔyopM mutant phenotype was postponed at least 24 hours, indicating that some virulence property of Y. pestis that was induced by the temperature transition compensated for the loss of YopM in the ΔyopM strain at an early stage of the infection. In general, these findings provide a framework for focusing future research to identify YopM’s direct molecular targets.

Final publication is available at http://dx.doi.org/10.1016/j.exer.2012.08.013. Congrong Guo, Atsushi Otani, Akio Oishi, Hiroshi Kojima, Yukiko Makiyama, Satoko Nakagawa, Nagahisa Yoshimura, Knockout of ccr2 alleviates photoreceptor cell death in a model of retinitis pigmentosa, Experimental Eye Research, Volume 104, November 2012, Pages 39-47, ISSN 0014-4835 / 京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18680号 / 医博第3952号 / 新制||医||1007(附属図書館) / 31613 / 京都大学大学院医学研究科医学専攻 / (主査)教授 長澤 丘司, 教授 伊藤 壽一, 教授 長田 重一 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

O processo de reparo ósseo depende de uma resposta inflamatória inicial e transitória, a qual envolve a participação de diversos leucócitos, como células da linhagem monócito/macrófago. O receptor CCR2 é importante para o recrutamento de macrófagos durante as respostas imunes, além de ter um papel na regulação da osteoclastogênese. Assim, o objetivo do presente estudo foi investigar papel de células CCR2+ no processo de reparo ósseo alveolar pós-exodontia em camundongos, por meio de análises microscópicas (MicroCT, histomorfometria, análise de birrefringência e imuno-histoquímica) e moleculares (PCRArray) comparativas entre as linhagens C57Bl/6 (WT) e CCR2KO, ao longo dos períodos de 0 hora, 7, 14 e 21 dias pós-exodontia do incisivo superior direito. Como resultado geral das análises microscópicas, constatamos que a ausência de células CCR2+ não afetou o resultado final do reparo ósseo alveolar em camundongos CCR2KO, mas levou a alterações transitórias e estatisticamente significantes (p<0,05) para quantificação de infiltrado inflamatório, vasos sanguíneos, fibroblastos, fibras colágenas, osteoblastos e osteoclastos. Além disso, a ausência de células CCR2+ resultou em diminuição (p<0,05) de células F4/80+ e CCR5+ no infiltrado inflamatório ao longo do processo de reparo ósseo alveolar de camundongos CCR2KO, demonstrando o papel do receptor CCR2 no recrutamento de macrófagos (células F4/80+), bem como sugerindo que as células F4/80+ apresentam dupla positividade para os receptores CCR2 e CCR5. Neste contexto, o receptor CCR5 seria o responsável pela migração remanescente, ainda que reduzida, de células F4/80+ nos animais CCR2KO. Considerando os resultados moleculares, a ausência de CCR2 resultou na alteração da expressão de diferentes marcadores em camundongos CCR2KO, tais como: o fator de crescimento TGF1, marcadores de matriz COL1, MMP1a, MMP2 e MMP9, marcadores ósseos RUNX2, DMP1, RANKL, RANK e CTSK, e marcadores de MSCs CD106, COT-4, NANOG, CD146 e CD105, bem como de marcadores imunológicos como as citocinas IL-6 e TNF-a, receptores de quimiocinas CCR1, CCR5 e CXCR1,e as quimiocinas CCL12, CCL20, CCL25 e CXCL12. Em conclusão, estes resultados indicam que células CCR2+ desempenham diferentes funções no reparo ósseo alveolar em camundongos, influenciando tanto a resposta inflamatória, como os eventos teciduais observados ao longo deste processo. / The bone repair process depends of an initial and transitory inflammatory response, which involves the participation of various leukocytes subsets, as of the monocyte/macrophage lineage. The CCR2 receptor is important to macrophage recruitment during immune responses, and play an active role in the regulation of osteoclastogenesis. Thereby, the purpose of this study was to investigate the role of CCR2+ cells in the alveolar bone repair process in mice, by means of microscopic (MicroCT, histomorphometry, birefringence analysis and immunohistochemistry) and molecular (PCRArray) comparative analysis between C57BL / 6 (WT) and CCR2KO mice during periods of 0 hour, 7, 14 and 21 days post-extraction of the right upper incisor. As a result of the microscopic analysis, we noted that the absence of CCR2+ cells did not affect in the overall outcome of alveolar bone repair in CCR2KO mice, but resulted in transient and statistically significant (p<0.05) alterations of inflammatory infiltrate, blood vessels, fibroblasts, collagen fibers, osteoblasts and osteoclasts counts. Furthermore, the absence of CCR2+cells resulted in a decrease (p<0.05) of CCR5+ and F4/80+ cells in the inflammatory infiltrate along the alveolar bone repair process in CCR2KO mice, demonstrating the role of CCR2 receptor in macrophages migration (F4/80+ cells), as well as suggesting that the F4/80+ cells are double positive for CCR2 and CCR5. In this context, CCR5 receptor could be responsible for the remaining (but reduced) migration, of the F4/80 + cells in CCR2KO mice. According to molecular results, the absence of CCR2 resulted in an altered expression of different markers in CCR2KO mice, such as: growth factor TGF1, the matrix markers COL1, MMP1a, MMP2 and MMP9, the bone markers RUNX2, DMP1 RANKL, RANK and CTSK, and MSCs markers CD106, OCT-4, NANOG, CD146 and CD105, as well as immunological markers as IL-6 and TNF-, chemokine receptors CCR1, CXCR1 and CCR5, and the chemokines CCL12, CCL20, CCL25 and CXCL12. In conclusion, these results indicate that CCR2+ cells have different functions in alveolar bone repair in mice, influencing the inflammatory response and also tissue events observed throughout the process events.

Monócitos podem ser classificados em três subgrupos de acordo com o nível de expressão dos marcadores CD14 e CD16. Monócitos clássicos são os mais abundantes no sangue. Eles expressam um fenótipo CD14+CD16-CCR2+, conferindo a eles a habilidade de migrar rapidamente a sítios inflamatórios, através da resposta à quimiocina CCL2 (CC chemokine ligand 2). Aqui apresentamos a identificação e caracterização de uma expansão de um novo subgrupo de monócitos durante a infecção por SIV e HIV. Essas células são indistinguíveis dos monócitos clássicos quanto à expressão de CD14 e CD16; porém não expressam CCR2 de superfície. A análise do transcriptoma de células selecionadas confirmou que elas representam uma subpopulação distinta que expressa níveis mais baixos de citocinas inflamatórias e marcadores de ativação que as CCR2+. Elas exibem fagocitose alterada e quimiotaxia deficiente em resposta a CCL2 e CCL7, além de serem refratárias à infecção por SIV e apresentarem atividade antiproliferativa. Nós as denominamos monócitos clássicos atípicos CCR2- (ACC monocytes), e acreditamos que elas têm um papel importante na patogenia da AIDS, possivelmente refletindo uma resposta anti-inflamatória contra a excessiva imunoativação observada durante a infecção por SIV e HIV. Tratamento antirretroviral leva a um declínio dessa subpopulação tanto em macacos como seres humanos, sugerindo que a replicação viral é capaz de induzir esse fenótipo atípico / Monocytes have been categorized in three main subpopulations based on CD14 and CD16 surface expression. Classical monocytes are the most abundant subset in the blood. They express a CD14+CD16-CCR2+ phenotype, which confers on them the ability to migrate to inflammatory sites by quickly responding to CC chemokine ligand 2 (CCL2) signaling. Here we identified and characterized the surge and expansion of a novel monocyte subset during SIV and HIV infection. They were undistinguishable from classical monocytes regarding CD14 and CD16 expression, but did not express surface CCR2. Transcriptome analysis of sorted cells confirmed that they represent a distinct subpopulation that expresses lower levels of inflammatory cytokines and activation markers than their CCR2+ counterparts. They exhibited impaired phagocytosis and deficient chemotaxis in response to CCL2 and CCL7, besides being refractory to SIV infection and showing antiproliferative activity. We named these cells atypical CCR2- classical (ACC) monocytes, and believe they play an important role in AIDS pathogenesis, possibly reflecting an anti-inflammatory response against the extreme immune activation observed during SIV and HIV infection. Antiretroviral therapy caused this population to decline in both macaque and human subjects, suggesting that this atypical phenotype may be induced by viral replication

O processo de reparo ósseo depende de uma resposta inflamatória inicial e transitória, a qual envolve a participação de diversos leucócitos, como células da linhagem monócito/macrófago. O receptor CCR2 é importante para o recrutamento de macrófagos durante as respostas imunes, além de ter um papel na regulação da osteoclastogênese. Assim, o objetivo do presente estudo foi investigar papel de células CCR2+ no processo de reparo ósseo alveolar pós-exodontia em camundongos, por meio de análises microscópicas (MicroCT, histomorfometria, análise de birrefringência e imuno-histoquímica) e moleculares (PCRArray) comparativas entre as linhagens C57Bl/6 (WT) e CCR2KO, ao longo dos períodos de 0 hora, 7, 14 e 21 dias pós-exodontia do incisivo superior direito. Como resultado geral das análises microscópicas, constatamos que a ausência de células CCR2+ não afetou o resultado final do reparo ósseo alveolar em camundongos CCR2KO, mas levou a alterações transitórias e estatisticamente significantes (p<0,05) para quantificação de infiltrado inflamatório, vasos sanguíneos, fibroblastos, fibras colágenas, osteoblastos e osteoclastos. Além disso, a ausência de células CCR2+ resultou em diminuição (p<0,05) de células F4/80+ e CCR5+ no infiltrado inflamatório ao longo do processo de reparo ósseo alveolar de camundongos CCR2KO, demonstrando o papel do receptor CCR2 no recrutamento de macrófagos (células F4/80+), bem como sugerindo que as células F4/80+ apresentam dupla positividade para os receptores CCR2 e CCR5. Neste contexto, o receptor CCR5 seria o responsável pela migração remanescente, ainda que reduzida, de células F4/80+ nos animais CCR2KO. Considerando os resultados moleculares, a ausência de CCR2 resultou na alteração da expressão de diferentes marcadores em camundongos CCR2KO, tais como: o fator de crescimento TGF1, marcadores de matriz COL1, MMP1a, MMP2 e MMP9, marcadores ósseos RUNX2, DMP1, RANKL, RANK e CTSK, e marcadores de MSCs CD106, COT-4, NANOG, CD146 e CD105, bem como de marcadores imunológicos como as citocinas IL-6 e TNF-a, receptores de quimiocinas CCR1, CCR5 e CXCR1,e as quimiocinas CCL12, CCL20, CCL25 e CXCL12. Em conclusão, estes resultados indicam que células CCR2+ desempenham diferentes funções no reparo ósseo alveolar em camundongos, influenciando tanto a resposta inflamatória, como os eventos teciduais observados ao longo deste processo. / The bone repair process depends of an initial and transitory inflammatory response, which involves the participation of various leukocytes subsets, as of the monocyte/macrophage lineage. The CCR2 receptor is important to macrophage recruitment during immune responses, and play an active role in the regulation of osteoclastogenesis. Thereby, the purpose of this study was to investigate the role of CCR2+ cells in the alveolar bone repair process in mice, by means of microscopic (MicroCT, histomorphometry, birefringence analysis and immunohistochemistry) and molecular (PCRArray) comparative analysis between C57BL / 6 (WT) and CCR2KO mice during periods of 0 hour, 7, 14 and 21 days post-extraction of the right upper incisor. As a result of the microscopic analysis, we noted that the absence of CCR2+ cells did not affect in the overall outcome of alveolar bone repair in CCR2KO mice, but resulted in transient and statistically significant (p<0.05) alterations of inflammatory infiltrate, blood vessels, fibroblasts, collagen fibers, osteoblasts and osteoclasts counts. Furthermore, the absence of CCR2+cells resulted in a decrease (p<0.05) of CCR5+ and F4/80+ cells in the inflammatory infiltrate along the alveolar bone repair process in CCR2KO mice, demonstrating the role of CCR2 receptor in macrophages migration (F4/80+ cells), as well as suggesting that the F4/80+ cells are double positive for CCR2 and CCR5. In this context, CCR5 receptor could be responsible for the remaining (but reduced) migration, of the F4/80 + cells in CCR2KO mice. According to molecular results, the absence of CCR2 resulted in an altered expression of different markers in CCR2KO mice, such as: growth factor TGF1, the matrix markers COL1, MMP1a, MMP2 and MMP9, the bone markers RUNX2, DMP1 RANKL, RANK and CTSK, and MSCs markers CD106, OCT-4, NANOG, CD146 and CD105, as well as immunological markers as IL-6 and TNF-, chemokine receptors CCR1, CXCR1 and CCR5, and the chemokines CCL12, CCL20, CCL25 and CXCL12. In conclusion, these results indicate that CCR2+ cells have different functions in alveolar bone repair in mice, influencing the inflammatory response and also tissue events observed throughout the process events.

Monócitos podem ser classificados em três subgrupos de acordo com o nível de expressão dos marcadores CD14 e CD16. Monócitos clássicos são os mais abundantes no sangue. Eles expressam um fenótipo CD14+CD16-CCR2+, conferindo a eles a habilidade de migrar rapidamente a sítios inflamatórios, através da resposta à quimiocina CCL2 (CC chemokine ligand 2). Aqui apresentamos a identificação e caracterização de uma expansão de um novo subgrupo de monócitos durante a infecção por SIV e HIV. Essas células são indistinguíveis dos monócitos clássicos quanto à expressão de CD14 e CD16; porém não expressam CCR2 de superfície. A análise do transcriptoma de células selecionadas confirmou que elas representam uma subpopulação distinta que expressa níveis mais baixos de citocinas inflamatórias e marcadores de ativação que as CCR2+. Elas exibem fagocitose alterada e quimiotaxia deficiente em resposta a CCL2 e CCL7, além de serem refratárias à infecção por SIV e apresentarem atividade antiproliferativa. Nós as denominamos monócitos clássicos atípicos CCR2- (ACC monocytes), e acreditamos que elas têm um papel importante na patogenia da AIDS, possivelmente refletindo uma resposta anti-inflamatória contra a excessiva imunoativação observada durante a infecção por SIV e HIV. Tratamento antirretroviral leva a um declínio dessa subpopulação tanto em macacos como seres humanos, sugerindo que a replicação viral é capaz de induzir esse fenótipo atípico / Monocytes have been categorized in three main subpopulations based on CD14 and CD16 surface expression. Classical monocytes are the most abundant subset in the blood. They express a CD14+CD16-CCR2+ phenotype, which confers on them the ability to migrate to inflammatory sites by quickly responding to CC chemokine ligand 2 (CCL2) signaling. Here we identified and characterized the surge and expansion of a novel monocyte subset during SIV and HIV infection. They were undistinguishable from classical monocytes regarding CD14 and CD16 expression, but did not express surface CCR2. Transcriptome analysis of sorted cells confirmed that they represent a distinct subpopulation that expresses lower levels of inflammatory cytokines and activation markers than their CCR2+ counterparts. They exhibited impaired phagocytosis and deficient chemotaxis in response to CCL2 and CCL7, besides being refractory to SIV infection and showing antiproliferative activity. We named these cells atypical CCR2- classical (ACC) monocytes, and believe they play an important role in AIDS pathogenesis, possibly reflecting an anti-inflammatory response against the extreme immune activation observed during SIV and HIV infection. Antiretroviral therapy caused this population to decline in both macaque and human subjects, suggesting that this atypical phenotype may be induced by viral replication

Made available in DSpace on 2016-07-13T19:05:36Z (GMT). No. of bitstreams: 2 mariana_cunha_ioc_dout_2015.pdf: 12334433 bytes, checksum: 5e288d54da3b70496ff176f2e68a6290 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil / Introdução: O CCR2 é o receptor do CCL2/MCP-1. O CCR2 é expresso em monócitos, células endoteliais, neutrófilos ativados, micróglia e astrócitos. Recentemente, alguns estudos mostram a expressão constitutiva do CCR2 e do CCL2 em regiões do sistema nervoso central, como o hipocampo. Como o hipocampo está envolvido com a consolidação de memória, nós analisamos o papel do CCR2 no processo de aprendizado e consolidação de memória. Métodos: Animais geneticamente deficientes para o CCR2 e animais controle foram submetidos a esquiva passiva e a natação forçada, para examinar a memória aversiva e a memória contextual. A resposta motora foi avaliada pelo ensaio de campo aberto, e o reflexo pelo teste de inibição de pré-pulso. Os animais foram submetidos a esquiva passiva de múltiplos treinos para analisar a curva de aprendizado e o esquecimento da memória. O próximo passo foi verificar a expressão de importantes mediadores envolvidos com a consolidação de memória por western blotting, como a ERK fosforilada e BDNF. E o ultimo passo foi verificar se a deficiência do CCR2 afeta a sinapse no hipocampo, pela expressão e co-localização de PSD95 e sinaptofisina por imunohistoquímica e a expressão de sinaptofisina e PSD95 por western blotting. Resultados: A ausência do CCR2, impediu a consolidação de memória aversiva e a memória contextual O animal deficiente para o CCR2 requer mais treinos para aprender na esquiva passiva e a memória decai de forma mais rápida, quando comparado com o grupo controle. A expressão de ERK fosforilada está reduzida 1 hora após um treino na esquiva passiva no hipocampo de animais deficientes para o CCR2 assim como a expressão de BDNF maduro está reduzida 12 horas após um treino na esquiva passiva. Nós observamos que a deficiência do CCR2 afeta a sinapse, com importante redução da co-localização entre sinaptofisina e PSD95 no hipocampo e redução na expressão de sinaptofisina no hipocampo. Os animais CCR2-/- tem aumento da expressão da proteina amilóide beta no hipocampo e no córtex cerebral ao redor dos vasos sanguíneos, associado com redução da perfusão sanguínea no cérebro, redução da expressão de caspases-3 e -12, sem diferença na expressão de IBA-1 e nos níveis de citocinas e quimiocinas no cérebro. Conclusão: A ausência do CCR2 altera a estrutura das sinapses, reduzindo a expressão da proteína pré-sináptica sinaptofisina e PSD95, bem como leva ao acúmulo de proteína amiloide beta no tecido cerebral, culminando com a disfunção cognitiva / Abstract: Background: CCR2 is the receptor for CCL2/MCP-1. CCR2 is expressed in monocytes, endothelial cells, activated neutrophils, microglial cells and astrocytes. Some studies show the constitutive expression of CCR2 and CCL2/MCP-1 in specific areas of the central nervous system, such as the hippocampus. Because the hippocampus is important for memory consolidation, we studied the role of CCR2 in learning process and in memory consolidation. Methods: CCR2 deficient mice and wild type were submitted to passive avoidance test and to water maze test, to evaluate aversive memory and contextual memory, respectively. The motor response was evaluated by open field test, while the reflex was evaluated by pre-pulse inhibitory response. The animals were submitted to passive avoidance test of multiple trials, to analyze the learning curve and the retrieval of memory. The next step was to verify the expression of proteins involved with memory consolidation, such as the phosphorylated ERK and mature BDNF by western blotting,. And the last step was to verify if the CCR2 deficiency affect the synapsis in hippocampus, by the expression and co-localization of PSD95 and synaptophysin using immunohistochemistry and the expression of synaptophysin and PSD95 by western blotting. Results: The absence of CCR2, impaired consolidation of aversive and contextual memories The CCR2 deficient mice required more trials to learn in passive avoidance test and the memory decay was faster, when compared to the wild type group. The expression of phosphorylated ERK is decreased 1 hour after one trial in passive avoidance test in the hippocampus of CCR2 deficient mice as was the expression of mature BDNF 12 hours after one trial in passive avoidance test. We observed that the deficiency of CCR2 affects the synapsis, with an important decrease in co-localization of PSD95 and synaptophysin in the hippocampus and decreased expression of synaptophysin in the hippocampus of CCR2 deficient mice. CCR2-/- animal had increased expression of beta amyloid protein around the blood vessels in the hippocampus and in the cortex, associated with decreased brain perfusion, increased expression of caspase-12 and caspase-3, but no difference in the expression of IBA-1 and in cytokines and chemokines levels. Conclusions: Absence of CCR2 changes the structure of synapsis, decreasing the pre-synaptic protein synaptophysin in hippocampus and also lead to accumulation of beta amyloid protein in brain tissue, culminating with cognitive dysfunction

Le sepsis est la réaction inflammatoire généralisée secondaire à une infection. C’est une pathologie fréquente et grave qui fait intervenir le système immunitaire. L’action de l’immunité innée se fait par l’activation et le recrutement des monocytes, des cellules mononuclées circulantes qui modulent le phénomène inflammatoire. La mobilisation des monocytes fait intervenir les cytokines chimiotactiques (chimiokines) et leurs récepteurs. Nous nous sommes spécifiquement intéressé dans ce travail au rôle de l’expression monocytaire des récepteurs aux chimiokines CCR2 et CX3CR1 au cours du sepsis. Pour ce faire, nous avons utilisé des modèles murins de sepsis et analysé le rôle d’un polymorphisme génétique de CX3CR1 dans une cohorte de malades atteints de sepsis. Nous avons montré qu’au cours du sepsis, les monocytes présentaient une augmentation de l’adhérence aux parois vasculaire contrôlée par le récepteur CX3CR1. Nous avons également montré que les monocytes inflammatoires jouaient un rôle essentiel dans la régulation du phénomène inflammatoire au cours du sepsis en protégeant le rein des lésions septiques. Cette protection est médiée par l’expression de CX3CR1. L’allèle I249 du gène Cx3cr1, à l’origine d’une augmentation des propriétés adhésives du couple CX3CR1/CX3CL1, est un facteur protecteur dans la survenue d’insuffisance rénale aiguë chez le malade atteint de sepsis. Collectivement, ces travaux confirment un rôle régulateur des monocytes inflammatoires au cours du sepsis et identifient de potentielles nouvelles cibles thérapeutiques. / Sepsis is the generalized inflammatory response secondary to an infection. This is a common and serious condition that involves the immune system. The action of innate immunity in sepsis is mediated by the activation and recruitment of monocytes, which are mononuclear circulating cells, which modulate the inflammatory process. The mobilization of monocytes involves chemotactic cytokines (chemokines) and their receptors. This work was specifically focused on the role of monocyte expression of chemokine receptors CCR2 and CX3CR1 in sepsis. To this end, we used mouse models of sepsis and analyzed the role of a common genetic polymorphism of CX3CR1 in a cohort of patients with sepsis.We have shown that in sepsis, monocytes’ motility was modified with an increase of their adhesion to vascular walls that was controlled in part by CX3CR1. We have also shown that inflammatory monocytes play a key role in the regulation of the inflammatory phenomenon in sepsis and that they protected the kidney from septic lesions via a CX3CR1 mediated adhesion mechanism. The I249 allele of CX3CR1, confering increased adhesive properties to monocytes, is a protective factor regarding the occurrence of acute kidney injury in septic patients. Collectively, these data confirm a a regulatory role for inflammatory monocytes during sepsis and identify potential new therapeutic targets.

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13454号 / 論医博第2247号 / 新制||医||1055(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 竹内 理, 教授 杉田 昌彦, 教授 生田 宏一 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM