Asthma is a chronic condition characterized by variable airflow obstruction, bronchial hyper-responsiveness, airway inflammation and remodeling. In spite of tremendous advances, the regulatory mechanisms controlling these pathological features have not yet been completely addressed. From an immunological perspective, type 2 inflammation and eosinophilic infiltration are the most striking hallmarks of asthma. At physiological level, structural changes such as increase in smooth muscle mass take the center stage which is usually associated with clinical measures of asthma. There might be some regulatory mediators capable of tuning airway inflammation and remodeling under homeostatic conditions but abrogated in asthmatic conditions. Semaphorin 3E (Sema3E) is an axon guidance molecule that is ubiquitously expressed and plays diverse roles in structural and inflammatory cells such as regulation of cell migration, proliferation and angiogenesis. However, its role in clinical and experimental asthma remains unclear. In this thesis, I have set out to uncover the expression and function of Sema3E in allergic asthma. It is generally hypothesized that Sema3E is down-regulated in allergic asthma which orchestrates the function of inflammatory (dendritic cells and neutrophils) and structural (airway smooth muscle) cells. Replenishment of Sema3E, which is suppressed under asthmatic conditions, could confer protection against allergic asthma by modulation of cellular functions. I began by comparing the expression of Sema3E between allergic asthmatics and healthy subjects. A remarkable down-regulation of Sema3E under asthmatic patients was observed which was further confirmed in a mouse model of the disease. Decreased expression of Sema3E was specifically demonstrated on bronchial epithelial cells obtained from asthmatic patients at both mRNA and protein levels. To address the function of Sema3E in allergic asthma in vivo, I extended my studies to mouse models of the disease and demonstrated that Sema3e gene deletion results in exacerbated allergic asthma pathology induced by allergen exposure. To investigate the translational relevance of my findings, I performed treatment of an asthmatic mouse model with exogenous Sema3E in which its intranasal administration attenuated airway inflammation, remodeling and hyper-responsiveness. The mechanism underlying Sema3E’s role in pathogenesis of allergic asthma was extensively studied indicating a crucial role of this mediator in modulation of dendritic cells and neutrophils functions. Our data demonstrated that both dendritic cells and neutrophils express the Sema3E high affinity receptor, PlexinD1, which makes them responsive to Sema3E treatment. Then, I studied expression and function of PlexinD1 on human airway smooth muscle (ASM) cells. I found that PlexinD1 surface expression was reduced on ASM cells from asthmatic patients. Treatment of ASM cells with Sema3E inhibited their proliferation and migration as the characteristic feature of airway remodeling. Suppression of Rac1 GTPase activity and phosphorylation of Akt/PI3K and ERK/MAPK were found as signaling mechanisms underlying Sema3E’s inhibitory effects. Together, these findings show that Sema3E thereby appears as a novel regulatory mediator, upstream of pro-allergic events, suggestive of a new approach to attenuate allergic asthma deficits. / May 2016

No description available.

La broncho-pneumopathie chronique obstructive (BPCO) est une maladie respiratoire inflammatoire chronique caractérisée par une limitation progressive et irréversible des débits aériens causée par l’inhalation à long terme de particules nocives telles que le tabac. La BPCO présente un remodelage majeur et hétérogène des voies aériennes comportant une grande variabilité inter-individuelle. La réponse inflammatoire et immunitaire au cours de la BPCO est caractérisée par une infiltration du tissu respiratoire par les polynucléaires neutrophiles (PN), les macrophages et par les cellules T. La dégradation des fibres élastiques du poumon en peptides solubles d’élastine (PE) par le biais de la sécrétion de protéases par les cellules de l’immunité innée est une caractéristique constante de la BPCO. Ces PE participent à la physiopathologie de la BPCO comme cela a été démontré dans différents modèles murins de la maladie emphysémateuse. L’orientation de la réponse des cellules T helper (Th) et des cellules T cytotoxiques (Tc) au cours de la BPCO n’est pas élucidée et reste controversée. L’objectif principal de ce travail de thèse a été de définir l’orientation de la réponse Th et Tc ainsi que le rôle des PE dans le remodelage associé à la BPCO. Pour cela, nous avons étudié la signature cytokinique Th-1/Tc-1 (IFN-), Th-2/Tc-2 (IL-4), Th-17/Tc-17 (IL-17) spécifique du remodelage bronchique associé à la BPCO au niveau cellulaire, mais également transcriptionnel et fonctionnel. L’association entre les résultats expérimentaux obtenus et le phénotype des patients inclus a été analysé de manière à déterminer le rôle de ces mécanismes dans l’expression clinique de cette pathologie respiratoire chronique. Les résultats obtenus ont mis en évidence une diminution de l’expression de l’IL-4 (Th2) chez les patients BPCO par rapport aux sujets contrôles ainsi qu’une potentialisation de l’expression de cette cytokine en présence des PE. / Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory respiratory pathology characterized by a progressive and irreversible limitation of airflow caused by the long-term inhalation of harmful particles such as tobacco. COPD presents a major and heterogeneous remodeling of the airways with important inter-individual variability. The inflammatory and immune response during COPD is characterized by infiltration of pulmonary tissue by neutrophils (PN), macrophages, and T cells. The degradation of lung elastic fibers into soluble elastin peptides (EP) is caused by the secretion of proteases by innate immunity cells and it is a consistent feature of COPD. These EP participate in the pathophysiology of COPD as demonstrated in different murine models of the emphysematous disease. The T helper (Th) and the T cytotoxic (Tc) orientation during COPD is unclear andremains controversial. The main objective of this work was to define the Th and Tc responses as well as the role ofEP in airways remodeling associated to COPD. For this purpose, we studied the cytokine signature Th-1/Tc-1 (IFN- ), Th-2/Tc-2 (IL-4), Th-17/Tc-17 (IL-17) specific of the airway remodeling associated to COPD both at the cellular, transcriptional and functional level. Association between the experimental results obtained and the phenotype of the patients included in the study was analyzed in order to determine the role of these mechanisms in the clinical expression of this chronic respiratory pathology. The results obtained showed a decrease in the expression of IL-4 (Th2) in COPD patients compared to control subjects as well as a potentiation of this cytokine expression in the presence of EP.

Asthma is a chronic disorder highlighted by intermittent airway inflammation and characterized by paroxysmal dyspnea and airway hyperresponsiveness (AHR). A key feature of severe asthma is the development of airway wall remodeling, which is thought to occur through repeated rounds of inflammation and tissue repair. Remodeling includes structural changes such as increased mass of airway smooth muscle (ASM), and excessive collagen deposition. ASM cells contribute to airway remodeling via the expression and secretion of extracellular matrix (ECM) proteins. This is particularly driven by inflammatory processes, which include mediators such as transforming growth factor (TGF)-β1 and damage associated molecular pattern (DAMP) proteins, such as high mobility group box 1 (HMGB1). HMGB1 is ubiquitously expressed as a non-histone DNA-binding protein that can regulate gene expression, but can also be released in response to stress to underpin inflammation and tissue repair. In this study we tested the hypothesis that extracellular HMGB1 induces signaling pathways that control responses linked to progression of airway inflammation, remodeling and hyperresponsiveness in human ASM cells. We used primary cultured ASM cells as well as hTERT-immortalized human ASM cells. With immunoblotting we demonstrate that exogenous HMGB1 (10 ng/mL) can induce rapid and sustained phosphorylation of p42/p44 mitogen-activated protein kinase (MAPK) that is comparable to that induced by a potent mitogen, platelet derived growth factor (PDGF-BB, 10 ng/mL). We also found that TGF-β1 (2.5 ng/mL) promotes the accumulation of secreted HMGB1 in culture medium in a time line concomitant with expression of ECM proteins, collagen and fibronectin, suggesting a role for HMGB1 in pro-fibrotic effects of TGF-β1. By lentiviral delivery, we induced stable expression of short hairpin RNA (shRNA) that silenced expression of endogenous HMGB1 or mammalian diaphanous 1 (mDia1), a cytoplasmic scaffold protein that is required for HMGB1-induced cell responses through one of its receptors, receptor for advanced glycation end products (RAGE). Immunoblot analyses revealed that silencing of mDia1 was associated with markedly decreased induction of p42/p44 MAPK phosphorylation by exogenous HMGB1. In HMGB1-silenced human ASM cells, we observed significantly reduced synthesis and secretion of collagen A1 and fibronectin in response to TGF-β1 (2.5 ng/mL, 0-48 hrs). However, exogenous HMGB1 was not sufficient to rescue ECM synthesis in response to TGF-β1 in HMGB1-silenced cells - this suggests that intracellular, but not necessarily secreted HMGB1, regulates ECM expression and secretion in response to TGF-β1. Consistent with this interpretation, exogenous HMGB1 alone was not sufficient to induce ECM synthesis or secretion in primary cultured ASM cells. In conclusion, we show that though in human ASM cells extracellular HMGB1 alone can activate MAPK signaling, likely via mDia1-dependent pathways involving RAGE. it is not capable of prompting ECM protein expression. Recombinanat exogenous HMGB1 does not appear to directly affect ECM synthesis, rather intracellular (nuclear) HMGB1 likely modulates activity of genes that are affected by TGF-β1. Overall, HMGB1 has potential to regulate tissue repair processes involving ASM through intracellular and extracellular mechanisms, thus our findings support further work to elucidate the role of HMGB1 in pathogenesis of obstructive airway disease.

Le remodelage bronchique regroupe des entités physiopaphologiques commel’hypertrophie musculaire lisse dans l’asthme ou l’augmentation d’épaisseur bronchique surl’infiltration de cellules inflammatoires et l’accumulation de fibrose dans la BPCO. Cesremodelages sont corrélés à l’obstruction fonctionnelle et donc à la sévèrité de ces maladies.L’analyse de biopsies bronchique ou pulmonaire permet d’étudier ce phénoméne qui, aprèsune meilleure compréhension, est une cible thérapeutique intérressante. Le premier articleest une revue d’indications de bronchoscopie chez les patients de réanimation. La deuxièmeétude a montré une augmentation des fibrocytes sanguins au cours d’exacerbation sévèrede patient BPCO et une corrélation entre leur taux et le risque de décès du patient. La voiede signalisation du CXCR4 semble impliquée dans ce recrutement. La troisième étudecherche à explorer la localisation et les caractéristiques intra-pulmonaires des fibrocyteschez le patient BPCO à l’état stable. La quatrième étude a montré, in vivo, que le gallopamil,un inhibiteur calcique, pouvait diminuer la taille de muscle lisse bronchique de patientasthmatique sévère en ciblant la biogenèse mitochondriale. Ceci pourrait en faire une armethérapeutique interressante et totalement novatrice. La dernière étude a permis d’isoler unphénotype de patient asthmatique non sévère à « muscle lisse bronchique augmenté » quiprésente un risque accru d’exacerbation et de contrôle non optimal de leur asthme. Lesmitochondries semblent jouer un rôle clé comme dans l’asthme sévère. / Airway remodeling groups pathophysiological entities such as smooth musclehypertrophy in asthma or increase bronchial thickness due to infiltration of inflammatory cellsand fibrosis in COPD. These remodeling is correlated with the functional obstruction andtherefore with the severity of these diseases. The bronchial or lung biopsies analysis allowsto study this phenomenon which, after understanding, is an interesting therapeutic target.The first article is a review of indications of bronchoscopy in critically ill patients. The secondstudy showed an increase in blood fibrocytes during severe exacerbation of COPD patientand a correlation between their rate and the risk of patient death. CXCR4 signaling pathwayseems to be involved in the fibrocyte recruitment. The third study seeks to explore thelocation and characteristics of intra-pulmonary fibrocytes in stable COPD patients. The fourthstudy has shown, in vivo, that gallopamil, a calcium channel blocker, could reduce airwaysmooth muscle size in severe asthmatic patient by targeting mitochondrial biogenesis. Thiscould make it an interesting therapeutic weapon and totally innovative. The last study hasisolated a non-severe asthma phenotype with "increased bronchial smooth muscle," whichpresents an increased risk of exacerbation and a suboptimal control of their asthma. Themitochondria appear to play a key role as in severe asthma.

A prevalência mundial de asma na infância é alta. Alterações estruturais das vias aéreas são observadas na asma, e podem ocorrer precocemente na infância. Este estudo tem como objetivo comparar os resultados de um modelo de sensibilização alérgica, em camundongos de diferentes idades. Para tanto foram utilizados camundongos Balb/C pré-desmamados, jovens e adultos. O grupo de animais pré desmamados foram divididos em outros dois grupos (18D 18D1), sendo que ambos foram sensibilizados com duas injeções intraperitoneal (i.p.) de 10 g ovalbumina (OVA) no 5º e 7º dia de vida. Após, o primeiro grupo de camundongos pré desmamados foram submetidos a 01 (um) desafio, este consistente em receberem inalações por 3 dias consecutivos, a 3% de OVA, por 10 minutos, nos dias 14, 15 e 16. O segundo grupo de camundongos pré desmamados foram submetidos 02 (dois) desafios, estes nos dias 09, 10 e 11; e 14, 15 e 16 dias de vida. O grupo de camundongos jovens (40D) receberam as mesmas inalações nos dias 22 a 24 e depois nos dias 36 a 38. Um quarto grupo de camundongos, denominados adultos (100D), foram sensibilizados com 10 g OVA i.p. nos dias 60 e 62 de vida; e também recebendo inalações por 3 dias consecutivos a 3% de OVA, por 10 minutos, nos dias 77 a 79 de vida, repetindo o procedimento nos dias 96, 97 e 98, sendo que os animais em todos os xiii grupos foram sacrificados 48hs após a última inalação. Todos os grupos possuíam um grupo controle respectivo, mesmo protocolo, mas ao invés de OVA, recebiam apenas solução salina. Observamos que os animais sensibilizados, quando comparados entre si, não apresentavam diferença quanto à densidade de células de eosinófilos (p = 0,052). A densidade de células TCD3+ foi maior nos camundongos adultos e no grupo de animais pré desmamados com dois desafios (p<0,001), não havendo diferença nos demais grupos (p=1,000). Foi possível observar também uma maior expressão de IL-5 nas vias aéreas quando comparados os grupos OVA de 18 dias de vida (18D e 18D1) com os seus controles (p=0,017). Todavia não houve esta diferença de IL-5 nos grupos jovens e adultos. Entre os grupos controles, a expressão de IL-5 foi menor nos grupos de 18 dias de vida (18D e 18D1) em relação aos animais dos grupos de 40 e 100 dias de vida (40D e 100D - p<0,001). Verificamos ainda que o grupo de animais pré desmamados com um desafio (p = 0,003) e os camundongos adultos (p = 0,006) apresentaram aumento da expressão de TGF- nas vias aéreas, quando comparados aos seus respectivos controles; e que os camundongos do grupo pré desmamado com um ou dois desafios apresentaram maior expressão de PAS no epitélio bronquiolar, quando comparado aos camundongos jovens e adultos (18D e 18D1 - p=0,007 e 40D e 100D - p=0,073). Entre os camundongos sensibilizados, o grupo pré desmamado com um único desafio, apresentou menor fração de área de colágeno comparado ao grupo de camundongos pré desmamados que receberam dois desafios (p<0,001), não havendo outras diferenças entre os grupos. xiv Camundongos jovens e adultos apresentaram um aumento de espessura do músculo liso da via aérea (MLB) quando comparados a seus respectivos controles (p = 0,048). Desta forma, foi possível demonstrar que os camundongos pré desmamados podem desenvolver alterações inflamatórias e estruturais nas vias aéreas, porém apresentam características diferentes das alterações observadas em animais com maior idade. Por fim, conclui-se que o presente estudo proporciona resultado e forma a ser utilizado como base para um estudo experimental, seja para verificar o resultado de medicamentos, seja para um estudo comparativo em crianças, jovens e adultos com asma, a fim de se verificar as diferenças apresentadas; e assim, auxiliar na adequada conduta clínica para prevenção ou combate dessa doença / The prevalence of childhood asthma is high worldwide. Recent data indicate that asthma structural changes occur early in childhood, and that structure alterations occur early in life. In this study we have aimed to compare a model of allergic sensitization in infantile, juvenile and adult mice. BALB/c mice at different ages were sensitized with two intraperitoneal injections (i.p.) of 10 g ovalbumin (OVA) at day 05 and 07 and received 3 daily inhalations of 3% OVA for 10 min on days 14 to 16 and 09 to 11 - 14 to 16 the infantile groups (18d - 18d1).The juvenile mice (40d) at days 22 to 24 - 36 to 38 and adult mice (100d) were sensitized with 3% OVA i.p. at day 60 and 62 and received 2x 3 daily inhalations at days 77-79 and at day 96-98, being euthanized 48h later. Control groups received saline using the same protocols. The OVA treated animals were compared among each other there were no differences regarding eosinophil cell density (p= 0.052). The density of T CD3+ cells was higher in the adult mice and in the infantile group with two challenges in relation to 18D e 40D (p=0.000), but without differences between the former groups (p= 1.000). When OVA groups were compared to the respective controls, infantile groups presented increased IL-5 expression in the airways (p=0.017), no differences were observed in the juvenile and adult mice. Among controls, IL-5 expression was lower in the infantile groups in relation to the juvenile and adult mice (p<0.001). The infantile group (p=0.003) with one challenge and the adult mice (p=0.006) presented increased TGF- expression in the airways when compared to their respective controls. Infantile mice with one or two challenges presented more PAS positivity in the bronchiolar epithelium than the juvenile and adult mice (p=0.007 and p=0.073). Among the OVA mice, infantile mice with one xvi challenge presented lower collagen area fraction than the group of infantile mice that received two challenges (p=0.000), without further differences among groups. Juvenile and adult mice had increased ASM thickness when compared to their age related controls (p=0.48). In summary, we have shown that infantile mice develop inflammatory and structural alterations in the airways, but that are partially different from those developed in older animals. Understanding the phenotypic differences in children vs adult asthma is very important to treat disease adequately and to manage prevention of severity

A prevalência mundial de asma na infância é alta. Alterações estruturais das vias aéreas são observadas na asma, e podem ocorrer precocemente na infância. Este estudo tem como objetivo comparar os resultados de um modelo de sensibilização alérgica, em camundongos de diferentes idades. Para tanto foram utilizados camundongos Balb/C pré-desmamados, jovens e adultos. O grupo de animais pré desmamados foram divididos em outros dois grupos (18D 18D1), sendo que ambos foram sensibilizados com duas injeções intraperitoneal (i.p.) de 10 g ovalbumina (OVA) no 5º e 7º dia de vida. Após, o primeiro grupo de camundongos pré desmamados foram submetidos a 01 (um) desafio, este consistente em receberem inalações por 3 dias consecutivos, a 3% de OVA, por 10 minutos, nos dias 14, 15 e 16. O segundo grupo de camundongos pré desmamados foram submetidos 02 (dois) desafios, estes nos dias 09, 10 e 11; e 14, 15 e 16 dias de vida. O grupo de camundongos jovens (40D) receberam as mesmas inalações nos dias 22 a 24 e depois nos dias 36 a 38. Um quarto grupo de camundongos, denominados adultos (100D), foram sensibilizados com 10 g OVA i.p. nos dias 60 e 62 de vida; e também recebendo inalações por 3 dias consecutivos a 3% de OVA, por 10 minutos, nos dias 77 a 79 de vida, repetindo o procedimento nos dias 96, 97 e 98, sendo que os animais em todos os xiii grupos foram sacrificados 48hs após a última inalação. Todos os grupos possuíam um grupo controle respectivo, mesmo protocolo, mas ao invés de OVA, recebiam apenas solução salina. Observamos que os animais sensibilizados, quando comparados entre si, não apresentavam diferença quanto à densidade de células de eosinófilos (p = 0,052). A densidade de células TCD3+ foi maior nos camundongos adultos e no grupo de animais pré desmamados com dois desafios (p<0,001), não havendo diferença nos demais grupos (p=1,000). Foi possível observar também uma maior expressão de IL-5 nas vias aéreas quando comparados os grupos OVA de 18 dias de vida (18D e 18D1) com os seus controles (p=0,017). Todavia não houve esta diferença de IL-5 nos grupos jovens e adultos. Entre os grupos controles, a expressão de IL-5 foi menor nos grupos de 18 dias de vida (18D e 18D1) em relação aos animais dos grupos de 40 e 100 dias de vida (40D e 100D - p<0,001). Verificamos ainda que o grupo de animais pré desmamados com um desafio (p = 0,003) e os camundongos adultos (p = 0,006) apresentaram aumento da expressão de TGF- nas vias aéreas, quando comparados aos seus respectivos controles; e que os camundongos do grupo pré desmamado com um ou dois desafios apresentaram maior expressão de PAS no epitélio bronquiolar, quando comparado aos camundongos jovens e adultos (18D e 18D1 - p=0,007 e 40D e 100D - p=0,073). Entre os camundongos sensibilizados, o grupo pré desmamado com um único desafio, apresentou menor fração de área de colágeno comparado ao grupo de camundongos pré desmamados que receberam dois desafios (p<0,001), não havendo outras diferenças entre os grupos. xiv Camundongos jovens e adultos apresentaram um aumento de espessura do músculo liso da via aérea (MLB) quando comparados a seus respectivos controles (p = 0,048). Desta forma, foi possível demonstrar que os camundongos pré desmamados podem desenvolver alterações inflamatórias e estruturais nas vias aéreas, porém apresentam características diferentes das alterações observadas em animais com maior idade. Por fim, conclui-se que o presente estudo proporciona resultado e forma a ser utilizado como base para um estudo experimental, seja para verificar o resultado de medicamentos, seja para um estudo comparativo em crianças, jovens e adultos com asma, a fim de se verificar as diferenças apresentadas; e assim, auxiliar na adequada conduta clínica para prevenção ou combate dessa doença / The prevalence of childhood asthma is high worldwide. Recent data indicate that asthma structural changes occur early in childhood, and that structure alterations occur early in life. In this study we have aimed to compare a model of allergic sensitization in infantile, juvenile and adult mice. BALB/c mice at different ages were sensitized with two intraperitoneal injections (i.p.) of 10 g ovalbumin (OVA) at day 05 and 07 and received 3 daily inhalations of 3% OVA for 10 min on days 14 to 16 and 09 to 11 - 14 to 16 the infantile groups (18d - 18d1).The juvenile mice (40d) at days 22 to 24 - 36 to 38 and adult mice (100d) were sensitized with 3% OVA i.p. at day 60 and 62 and received 2x 3 daily inhalations at days 77-79 and at day 96-98, being euthanized 48h later. Control groups received saline using the same protocols. The OVA treated animals were compared among each other there were no differences regarding eosinophil cell density (p= 0.052). The density of T CD3+ cells was higher in the adult mice and in the infantile group with two challenges in relation to 18D e 40D (p=0.000), but without differences between the former groups (p= 1.000). When OVA groups were compared to the respective controls, infantile groups presented increased IL-5 expression in the airways (p=0.017), no differences were observed in the juvenile and adult mice. Among controls, IL-5 expression was lower in the infantile groups in relation to the juvenile and adult mice (p<0.001). The infantile group (p=0.003) with one challenge and the adult mice (p=0.006) presented increased TGF- expression in the airways when compared to their respective controls. Infantile mice with one or two challenges presented more PAS positivity in the bronchiolar epithelium than the juvenile and adult mice (p=0.007 and p=0.073). Among the OVA mice, infantile mice with one xvi challenge presented lower collagen area fraction than the group of infantile mice that received two challenges (p=0.000), without further differences among groups. Juvenile and adult mice had increased ASM thickness when compared to their age related controls (p=0.48). In summary, we have shown that infantile mice develop inflammatory and structural alterations in the airways, but that are partially different from those developed in older animals. Understanding the phenotypic differences in children vs adult asthma is very important to treat disease adequately and to manage prevention of severity

Airway remodeling in asthma includes alterations in extracellular matrix and airway smooth muscle (ASM) mass. For this study, ASM cells were obtained from rats that were challenged with ovalbumin (OVA) or saline (SAL) as control. OVA and SAL cells were seeded on plastic control (PC) or on plates coated with decorin or biglycan. OVA cell number was significantly increased versus SAL cells, for cells seeded on PC (48 h). A significant decrease in cell number was observed for both OVA and SAL cells seeded on decorin compared to PC cells (48 h). OVA cells, however, showed a more modest reduction in cell number. Furthermore, biglycan decreased SAL cell number only. Compared to no strain (NS), mechanical strain (S) reduced cell number for OVA and SAL cells on all matrices. In addition, S up-regulated expression of beta 1-integrin relative to NS controls. Results suggest an ability of ASM cells to be modulated by matrix and mechanical stimulation.

Le remodelage des voies aériennes est un phénomène mal connu, dont le rôle est central dans la sévérité des maladies broncho-pulmonaires obstructives chroniques telles que l’asthme et la broncho-pneumopathie obstructive chronique (BPCO). La recherche est nécessaire pour comprendre les mécanismes et les conséquences fonctionnelles, qui diffèrent dans ces deux maladies. L’imagerie a le potentiel de pouvoir évaluer de façon non-invasive, in vivo, les mécanismes mis en oeuvre dans ces maladies tandis que la recherche de marqueurs pertinents est une nécessité. Dans l’asthme, chez l’animal, nous avons évalué la densité péribronchique dans des modèles murins de sensibilisation allergique. Ce marqueur a été démontré comme étant un reflet du remodelage des voies aériennes et pourrait être utilisé dans des études précliniques. Chez l’homme, nous avons d’abord optimisé les performances d’un logiciel de segmentation 3D des volumes bronchiques, en termes d’automatisation, détection de bronches distales et squelettisation. Ce logiciel a été appliqué lors d’une étude thérapeutique en double aveugle versus placebo pour évaluer l’effet du gallopamil dans l’asthme sévère. Nos résultats montrent que le remodelage musculaire lisse est une composante clé du remodelage dans l’asthme, et que le TDM quantitatif permet d’évaluer les effets de molécules lors d’essais cliniques. Dans la BPCO, nous avons mis en évidence à l’aide de la TDM quantitative que le remodelage bronchique est impliqué dans une complication particulière qui n’est pas mise en oeuvre dans l’asthme, à savoir le développement d’une hypertension artérielle pulmonaire. D’autre part, nous avons montré que la mesure automatique des petits vaisseaux permet une analyse complémentaire et supporte l’hypothèse d’un phénotype distinct de BPCO associé à une maladie vasculaire. Enfin l’IRM pulmonaire reste un challenge pour l’imagerie du fait de la faible teneur en protons et des mouvements cardiaque et respiratoire. Nous avons testé et optimisé une nouvelle séquence permettant d’obtenir des imageries de qualité très proches de celles du TDM. Ces résultats ouvrent des perspectives sur l’imagerie non irradiante des maladies broncho-pulmonaires chroniques par IRM. / Airway remodeling is a critical outcome in broncho-pulmonary obstructive disorders such as asthma, COPD and cystic fibrosis. Research is needed in order to better understand the pathophysiological process underlying these different diseases, as well as their functional significance and consesquences in vivo. Imaging allows non-invasive and quantitative assessment of the remodeling process in vivo. In asthma, we have assessed the value of peribronchial density using microCT in murine models of ovalbumine sensitization. This novel biomarker was shown to relate with remodeling than inflammation of airways and could be used in preclinical studies. In humans, we first optimized an existing chain of post treatment in order to segment in 3 dimensions bronchi volumes in order to improve automation, detection and skeletonization. The software was applied in a prospective randomized double-blinded study in severe asthma, in order to test the effect of a new therapeutic anticalcic agent. Results showed that the software enables a non-invasive assessment of airway smooth muscle remodeling in severe asthma during therapeutic studies. In COPD, we have shown that quantitative CT is able to unravel new complex mechanisms that are involved in COPD but not in asthma, i.e. the development of pulmonary hypertension. CT measurements of small vessels were also shown to add complementary information on COPD phenotypes, supporting the existence of distinct subtypes of COPD related to a vascular rather than a broncho-pulmonary disease. Finally, lung MRI is still a challenging field of investigation, owing to the very low proton density of bronchi, the presence of movement artifact. We have tested and optimized an innovative sequence combined with respiratory synchronization in order to get images in close agreement with CT. Perspectives related to this novel non-invasive, quantitative and radiation-free imaging technique are promising in the evaluation of broncho-pulmonary obstructive diseases.

No description available.