Each year, aging and age-related deficits in cognitive function affect larger population worldwide. Research on aging has focused on changes in gray matter and white matter with age. A quantitative analysis of magnetic resonance images from healthy subjects of 16-79 years showed a significant negative correlation between gray matter volume and age (Taki et al., 2004). In addition, age-related cognitive decline is reported to be associated with white matter changes such as myelin damage, a result of both the inability of microglia to clear out damaged myelin debris and oligodendrocyte to support remyelination. Eotaxin-1 (CCL11) belongs to a group of eosinophil-specific chemoattractant originally found in peripheral immune system mediating allergic inflammation, asthma and atopic dermatitis (Garcia-Zepeda et al., 1996; Spergel, Mizoguchi, Oettgen, Bhan, & Geha, 1999). Recently it has been reported to have endogenous sources in the CNS and to increase with age in cerebral spinal fluid (CSF) as well as periphery in blood plasma. While CCL11 has been identified to increase with age, injection of CCL11 inhibit neurogenesis in young mice, which is likely to be mediated by C-C chemokine receptor type 3 (CCR3). CCR3 is also the only receptor for CCL11 that is expressed by oligodendrocyte precursor cells (OPCs) and by activated microglia in mice, which means it may participate in the process of microglial phagocytosis and oligodendrocyte myelination. To investigate if CCR3 is an important factor in the normal aging brain and its potential role in these existing findings, immunohistochemistry, stereology and densitometry were performed in the anterior cingulate cortex and cingulum from brain tissue of 4 young adults and 6 aged rhesus monkeys that were behaviorally tested previously to 1) demonstrate any association between CCR3 expression level and age 2) characterize changes in CCR3 level in relation to cognitive impairment 3) identify cellular localization of CCR3. We found a significant increase in amount of CCR3 cingulate cortex with age, which suggests its pro-disease effect in other pathways such as the interaction between CNS and T cell immune system. Although for aged group increase in CCR3+ cell density in white matter appeared insignificant, we found that CCR3 was expressed exclusively in OPCs but was absent in mature oligodendrocytes. indicating its role in OPC proliferation, oligodendrocyte maturation and myelination.

Des cellules immunitaires appartenant à l’immunité de type 3 sont localisées dans muqueuse digestive. Les micro-organismes du microbiote stimulent le système immunitaire pour le maintenir en veille face à de potentiels agents infectieux, tout en ayant une tolérance pour les micro-organismes commensaux. Des études montrent des anomalies du microbiote intestinal chez les patients arthritiques. Ceci suggère une dérégulation de l’immunité mucosale digestive dans la survenue de l’inflammation articulaire. Des cellules de l’immunité mucosale pourraient migrer vers les sites articulaires, notamment grâce à des récepteurs aux chimiokines. Le facteur RORγt, indispensable à la différenciation des cellules de l’immunité de type 3, est régulé négativement par le récepteur PPARγ. A l’aide de modèle murins, nous avons étudié l’impact de l’invalidation de PPARγ et de l’inhibition du récepteur aux chimiokines CCR3 sur les relations entre sphères digestive et articulaire. Nous avons montré que l’induction d’une colite au cours d’une arthrite au collagène modifie le microbiote intestinal, retarde l’apparition et diminue la sévérité des lésions articulaires. Nous avons démontré que les souris PPARγ-/- développent spontanément une inflammation articulaire associées à des anomalies dans la répartition des cellules immunitaires de type 3 de la muqueuse digestive. Ces souris sont dysbiotiques avec une flore enrichie notamment en entérobactéries, mais non-arthritogène. Enfin, l’inhibition de CCR3 au cours du développement d’une arthrite au collagène retarde et diminue la sévérité de la pathologie et altère la répartition des leucocytes dans les articulations et de la muqueuse digestive / Numerous type 3 immune cells (Th17 and ILC3) are physiologically located in lamina propria of the intestine. Microbial agents within the gut shape the immune system to make it efficient against threats but peaceful with commensals. Recent studies demonstrated changes in gut microbiota composition (dysbiosis) in chronic inflammatory rheumatism. These results suggest a role for mucosal immunity alteration in articular inflammation occurrence. Indeed, some type 3 immune cells once activated by microbiota, are thought to migrate to joints, involving notably chemokines receptors. Transcription factor RORγt, the master regulator of type 3 immune cells, could be negatively regulated by nuclear receptor PPARγ. Using experimental murine models, we studied the consequence of PPARγ deficiency and consequence of the chemokine receptor CCR3 inhibition on the joint-gut axis. Firstly, we demonstrated that experimental colitis induces microbiota changes, delays and reduces collagen-induced arthritis severity. Secondly, we showed that PPARγ deficient mice display spontaneous joint inflammation associated with abnormal type 3 distribution within the gut. Dysbiosis with enrichment in facultative anaerobic Enterobacteriaceae was found in these mice. Fecal microbiota transfer demonstrated this microbiota is non-arthritogenic. Finally, we demonstrated that CCR3 inhibition has profound anti-arthritic potencies associated with changes in leukocytes distribution within the joint-gut axis

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Eosinophils are commonly described as cells from innate immunity that act on parasitic infections and lung diseases. However, in recent years, new functions are being added to these cells, among them, the maintenance of reproductive homeostasis. In addition, since the 1960s, studies have shown the estrogen relationship and the selective eosinophils migration to the uterus of castrated rats. The elucidation of the mechanism for the migration of these cells appears to be based on findings showing that the CCR3 receptor and its CCL11 chemokine are expressed in the human endometrium. Objective: The objective of this study was to evaluate the CCR3 participation in the eosinophils migration to the uterus of castrated mice, induced by 17-β-estradiol (E2). Methods: C57/BL6 mice, which received subcutaneous E2 injection, were used to determine the time and dose response of E2 (times 6, 12, 24 and 48 hours and doses of 0.1, 1, 3, 10, 30, 100 and 300 μg/kg) that promotes uterine weight gain and eosinophil migration. Subsequently, using the air bubble model, we sought to standardize CCL11- induced eosinophil recruitment, and the dose of the CCR3 antagonist (SB 328437 at doses of 1, 3 and 10 mg/kg) which promotes reduction in eosinophils migration. In addition, in the same model, the effect of the uterine extract with and without the administration of E2 (at the times of 6, 12 and 24 h) on the leukocyte migration was evaluated. Finally, an investigation was carried out on the effect of SB 328437 on uterine weight and eosinophil recruitment. The eosinophil peroxidase (EPO) absorbance and histology were used to evaluate the eosinophil migration, in which the uterus was stained with orcein specific for eosinophils. Results: The results demonstrated that the dose of 100 μg/kg E2 in the 24 hour period promoted a 40% increase in uterine weight, accompanied by eosinophil migration. In the air bubble model, it was observed that CCL11 recruited eosinophils, and SB 328437 promoted a 55% reduction in migration of these cells. The extract of the uterus caused the migration of total and eosinophilic leukocytes, but there was no difference between the groups with and without the administration of E2. Corroborating the results of SB 328437 in the air bubble experiment, the evaluation of its effect on uterine weight and eosinophils recruitment demonstrated that dose of 3 mg/kg reduced both parameters (approximately 45% and 56%, respectively) when stimulated with E2. The results were analyzed using ANOVA with Tukey post-test (more than two groups), and t test (two groups). Conclusion: Based on the results, it was possible to confirm the hypothesis that the CCR3 receptor participates in the eosinophils migration to the uterus of C57/BL6 mice after E2 induction. Furthermore, it represents an important pathway to be considered in studies aimed at elucidating mechanisms in in physiological and pathological processes involving the eosinophils recruitment. / Os eosinófilos são comumente descritos como células pertencentes à imunidade inata que agem em infecções parasitárias e nas doenças pulmonares. Porém, nos últimos anos, novas funções estão sendo acrescidas a essas células, dentre as quais, de manutenção da homeostase reprodutiva. Além disso, desde a década de 60, estudos demonstraram a relação do estrogênio com a migração seletiva de eosinófilos para o útero de ratas castradas. A elucidação do mecanismo para a migração dessas células baseia-se em achados evidenciando que o receptor CCR3 e sua quimiocina CCL11 estão expressos no endométrio humano. Objetivo: Diante do exposto, o estudo objetivou avaliar a participação do CCR3 na migração de eosinófilos para o útero de camundongos castrados, induzida por 17-β-estradiol (E2). Metodologia: Camundongos C57/BL6 receberam a injeção de E2 subcutânea, objetivando determinar o tempo e a dose resposta do E2 (tempos de 6, 12, 24 e 48 horas e doses de 0,1, 1, 3, 10, 30, 100 e 300 μg/kg) que promove aumento do peso do útero e migração de eosinófilos. Posteriormente, utilizando o modelo de bolha de ar, buscou-se padronizar o recrutamento de eosinófilos induzido por CCL11, e a dose do antagonista do CCR3 (SB 328437, nas doses de 1, 3 e 10 mg/kg) que promove redução da migração de eosinófilos. Ademais, no mesmo modelo, avaliou-se o efeito do extrato do útero com e sem a administração de E2 (nos tempos de 6, 12 e 24 h), na migração de leucócitos. Por último, foi realizada uma investigação sobre o efeito do SB 328437 no peso do útero e no recrutamento de eosinófilos. Para avaliação da migração de eosinófilos foi utilizada a absorbância da Peroxidase de Eosinófilos (EPO) e a histologia, no qual, os úteros foram corados com orceína, específico para eosinófilos. Resultados: Os resultados demonstraram que a dose de 100 μg/kg de E2 no tempo de 24 horas promoveu aumento de 40% no peso do útero, acompanhado da migração de eosinófilos. No modelo de bolha de ar, observou-se que a CCL11 recrutou os eosinófilos, e o SB 328437 promoveu redução de 55% na migração dessas células. O extrato do útero provocou a migração de leucócitos totais e de eosinófilos, porém não houve diferença entre os grupos com ou sem a administração de E2. Corroborando os resultados do SB 328437 no experimento da bolha de ar, a avaliação do efeito do antagonista no peso do útero e no recrutamento de eosinófilos, demonstrou que a dose de 3 mg/kg reduziu ambos os parâmetros (aproximadamente em 45% e 56%, respectivamente) quando estimulados com E2. Os resultados foram analisados utilizando o ANOVA com pós- teste de Tukey (mais de dois grupos), e o teste t (em dois grupos). Conclusão: Perante os resultados encontrados, foi possível confirmar a hipótese de que o receptor CCR3 participa da migração de eosinófilos para o útero de camundongos C57/BL6, após indução com E2. Outrossim, representa uma importante via a ser considerada em estudos que visam a elucidação de mecanismos em processos fisiológicos e patológicos envolvendo o recrutamento de eosinófilos. / São Cristóvão, SE

Introdução: A dermatite atópica (DA) é uma doença cutânea inflamatória de caráter crônico, recidivante, em que o prurido intenso e a xerose cutânea são frequentes. A etiopatogenia da DA é multifatorial, envolvendo fatores genéticos, ambientais e imunológicos. Eosinófilos são leucócitos polimorfonucleares multifuncionais que estão implicados na patogênese de diversos processos inflamatórios, incluindo a DA. Além da produção e secreção de diversas proteínas presentes nos grânulos citoplasmáticos, os eosinófilos também apresentam potencial para secretar metaloproteinases, enzimas proteolíticas que degradam vários componentes da matriz extracelular, e estão presentes em diversos processos fisiológicos e patológicos. Objetivo: Avaliar: 1) o perfil fenotípico dos eosinófilos na dermatite atópica do adulto, através da expressão das moléculas CCR3, CD23, CD38, CD69 e CD62L; 2) o perfil funcional, a partir da secreção de metaloproteinases, inibidores teciduais de metaloproteinases e RANTES por eosinófilos purificados. Métodos: Foram incluídos 41 adultos diagnosticados com DA, de acordo com os critérios de Hanifin & Rajka e 45 controles adultos sadios. A gravidade da doença foi mensurada através do escore de gravidade EASI (Eczema Area and Severity Index). Eosinófilos (LIN 1- CCR3+) do sangue periférico foram analisados para os marcadores CCR3, CD38, CD69, CD23 e CD62L através da citometria de fluxo (LSRFortessa, BD Biosciences) a análise foi realizada com o FlowJo 7.5.6 software. Eosinófilos purificados de indivíduos com DA e indivíduos controles foram estimulados com enterotoxina de Staphylococcus aureus B (SEB) e FSL-1 (agonista de receptores Toll-like 2 e 6), e os sobrenadantes foram coletados para dosagem de metaloproteinases (MMPs), inibidores teciduais de metaloproteinases 1 e 2 (TIMP-1 e TIMP-2) e RANTES por ELISA e por Cytometric bead array. Resultados: Indivíduos com DA apresentaram maior frequência de eosinófilos (LIN1- CCR3+), relacionada à gravidade da doença. Observou-se também, que a frequência de CD62L (L-selectina) e de CD23 (receptor de baixa afinidade para IgE) em eosinófilos (LIN1- CCR3+) diminui em pacientes com DA. Os receptores de ativação precoce (CD69) e tardio (CD38) não mostraram diferença estatística entre os grupos analisados. Os níveis séricos de MMPs e de TIMPs foram similares entre os controles e pacientes. Ao analisarmos a secreção de MMPs e de (TIMPs), a partir de eosinófilos purificados de pacientes com dermatite atópica, observamos diminuição dos níveis basais de TIMP-1 e TIMP-2 e de RANTES. Conclusões: Na DA do adulto, o perfil fenotípico e funcional dos eosinófilos mostrou: perfil de ativação da fase aguda, com expressão aumentada de CCR3; potencial de migração elevado, em decorrência da diminuição da expressão de CD62L; falhas no processo de ativação dos eosinófilos via CD23, bem como, no remodelamento tecidual mediado por TIMP-1 e TIMP-2 e na quimotaxia mediada por RANTES / Introduction: Atopic dermatitis (AD) is an inflammatory, chronic and recurrent skin disease characterized by intense pruritus and xerosis. AD has a complex etiopathogenesis, which involves the influence of genetics, environment, and immunological disorders, among others. Eosinophils are multifunctional polymorphonuclear leukocytes that contribute to the pathogenesis of several inflammatory processes, such as AD. In addition to the production and secretion of diverse proteins of the cytoplasmic granules, eosinophils have also the potential to secrete metalloproteinases (MMPs), proteolytic enzymes with a primary role for degrading several extracellular matrix components, present in distinct physiological and pathological processes. Objective: To evaluate:1) the phenotypic profile of eosinophils in adults with atopic dermatitis through the expression of CCR3, CD23, CD38, CD69 and CD62L molecules; 2) the functional profile through secretion of MMPs, tissue inhibitors of metalloproteinases 1 and 2 ( TIMP-1 and TIMP-2) and RANTES by purified eosinophils. Methods: This work enrolled 41 patients with AD, diagnosed according to Hanifin & Rajka\'s criteria) and 45 healthy controls. Severity of the disease was established utilizing EASI (Eczema Area and Severity Index). Eosinophils (Lineage cocktail 1- CCR3+) from peripheral blood were analyzed for CCR3, CD38, CD69, CD23 and CD62L by flow cytometry (LSRFortessa, BD Biosciences), and analysis was performed using the FlowJo 7.5.6 software. Purified eosinophils were stimulated with Staphylococcus aureus enterotoxin B (SEB) FSL-1 (Toll-like receptor 2/6 agonist), and supernatants were collected for MMPs, TIMPs and RANTES secretion, evaluated by ELISA and cytometric bead array (CBA). Results: Patients with AD have a higher frequency of eosinophils (LIN1- CCR3+), related to disease severity. Moreover, the frequency of CD62L (L-selectin) and CD23 (low-affinity receptor for IgE) in (LIN1- CCR3+) eosinophils was reduced in individuals with AD. CD69 and CD38 (early and late activation receptors) did not show significant difference in the studied groups. Serum levels of MMPs and of TIMP-1 and TIMP-2 were similar in healthy controls and AD patients. When analyzing secretion of MMPs and TIMPs by purified eosinophils from AD individuals, we detected a decrease in baseline levels of TIMP-1, TIMP-2, and reduced RANTES-mediated chemotaxis. Conclusions: Eosinophils in AD exhibit an activation profile of acute phase, with enhanced CCR3 expression, high potential for migration due to reduced expression of CD62, defective activation mechanisms via CD23, altered tissue remodeling process mediated by TIMP-1 and TIMP-2 and reduced RANTES-mediated chemotaxis

Introdução: A dermatite atópica (DA) é uma doença cutânea inflamatória de caráter crônico, recidivante, em que o prurido intenso e a xerose cutânea são frequentes. A etiopatogenia da DA é multifatorial, envolvendo fatores genéticos, ambientais e imunológicos. Eosinófilos são leucócitos polimorfonucleares multifuncionais que estão implicados na patogênese de diversos processos inflamatórios, incluindo a DA. Além da produção e secreção de diversas proteínas presentes nos grânulos citoplasmáticos, os eosinófilos também apresentam potencial para secretar metaloproteinases, enzimas proteolíticas que degradam vários componentes da matriz extracelular, e estão presentes em diversos processos fisiológicos e patológicos. Objetivo: Avaliar: 1) o perfil fenotípico dos eosinófilos na dermatite atópica do adulto, através da expressão das moléculas CCR3, CD23, CD38, CD69 e CD62L; 2) o perfil funcional, a partir da secreção de metaloproteinases, inibidores teciduais de metaloproteinases e RANTES por eosinófilos purificados. Métodos: Foram incluídos 41 adultos diagnosticados com DA, de acordo com os critérios de Hanifin & Rajka e 45 controles adultos sadios. A gravidade da doença foi mensurada através do escore de gravidade EASI (Eczema Area and Severity Index). Eosinófilos (LIN 1- CCR3+) do sangue periférico foram analisados para os marcadores CCR3, CD38, CD69, CD23 e CD62L através da citometria de fluxo (LSRFortessa, BD Biosciences) a análise foi realizada com o FlowJo 7.5.6 software. Eosinófilos purificados de indivíduos com DA e indivíduos controles foram estimulados com enterotoxina de Staphylococcus aureus B (SEB) e FSL-1 (agonista de receptores Toll-like 2 e 6), e os sobrenadantes foram coletados para dosagem de metaloproteinases (MMPs), inibidores teciduais de metaloproteinases 1 e 2 (TIMP-1 e TIMP-2) e RANTES por ELISA e por Cytometric bead array. Resultados: Indivíduos com DA apresentaram maior frequência de eosinófilos (LIN1- CCR3+), relacionada à gravidade da doença. Observou-se também, que a frequência de CD62L (L-selectina) e de CD23 (receptor de baixa afinidade para IgE) em eosinófilos (LIN1- CCR3+) diminui em pacientes com DA. Os receptores de ativação precoce (CD69) e tardio (CD38) não mostraram diferença estatística entre os grupos analisados. Os níveis séricos de MMPs e de TIMPs foram similares entre os controles e pacientes. Ao analisarmos a secreção de MMPs e de (TIMPs), a partir de eosinófilos purificados de pacientes com dermatite atópica, observamos diminuição dos níveis basais de TIMP-1 e TIMP-2 e de RANTES. Conclusões: Na DA do adulto, o perfil fenotípico e funcional dos eosinófilos mostrou: perfil de ativação da fase aguda, com expressão aumentada de CCR3; potencial de migração elevado, em decorrência da diminuição da expressão de CD62L; falhas no processo de ativação dos eosinófilos via CD23, bem como, no remodelamento tecidual mediado por TIMP-1 e TIMP-2 e na quimotaxia mediada por RANTES / Introduction: Atopic dermatitis (AD) is an inflammatory, chronic and recurrent skin disease characterized by intense pruritus and xerosis. AD has a complex etiopathogenesis, which involves the influence of genetics, environment, and immunological disorders, among others. Eosinophils are multifunctional polymorphonuclear leukocytes that contribute to the pathogenesis of several inflammatory processes, such as AD. In addition to the production and secretion of diverse proteins of the cytoplasmic granules, eosinophils have also the potential to secrete metalloproteinases (MMPs), proteolytic enzymes with a primary role for degrading several extracellular matrix components, present in distinct physiological and pathological processes. Objective: To evaluate:1) the phenotypic profile of eosinophils in adults with atopic dermatitis through the expression of CCR3, CD23, CD38, CD69 and CD62L molecules; 2) the functional profile through secretion of MMPs, tissue inhibitors of metalloproteinases 1 and 2 ( TIMP-1 and TIMP-2) and RANTES by purified eosinophils. Methods: This work enrolled 41 patients with AD, diagnosed according to Hanifin & Rajka\'s criteria) and 45 healthy controls. Severity of the disease was established utilizing EASI (Eczema Area and Severity Index). Eosinophils (Lineage cocktail 1- CCR3+) from peripheral blood were analyzed for CCR3, CD38, CD69, CD23 and CD62L by flow cytometry (LSRFortessa, BD Biosciences), and analysis was performed using the FlowJo 7.5.6 software. Purified eosinophils were stimulated with Staphylococcus aureus enterotoxin B (SEB) FSL-1 (Toll-like receptor 2/6 agonist), and supernatants were collected for MMPs, TIMPs and RANTES secretion, evaluated by ELISA and cytometric bead array (CBA). Results: Patients with AD have a higher frequency of eosinophils (LIN1- CCR3+), related to disease severity. Moreover, the frequency of CD62L (L-selectin) and CD23 (low-affinity receptor for IgE) in (LIN1- CCR3+) eosinophils was reduced in individuals with AD. CD69 and CD38 (early and late activation receptors) did not show significant difference in the studied groups. Serum levels of MMPs and of TIMP-1 and TIMP-2 were similar in healthy controls and AD patients. When analyzing secretion of MMPs and TIMPs by purified eosinophils from AD individuals, we detected a decrease in baseline levels of TIMP-1, TIMP-2, and reduced RANTES-mediated chemotaxis. Conclusions: Eosinophils in AD exhibit an activation profile of acute phase, with enhanced CCR3 expression, high potential for migration due to reduced expression of CD62, defective activation mechanisms via CD23, altered tissue remodeling process mediated by TIMP-1 and TIMP-2 and reduced RANTES-mediated chemotaxis

Asthma is a respiratory disease that affects 2.5-3 million Canadians. This condition is characterized by a Th2-driven immune response that implicates the infiltration of eosinophils and remodelling of the airways. In the last decade, airway smooth muscle cells (ASMC) have became the subject of intense research in the field of inflammatory lung diseases including asthma. It is known that ASMC respond to a wide variety of inflammatory mediators such as cytokines and chemokines. Function of ASMC in the context of asthma has extended beyond its traditional role of a structural cell. Indeed, it is believed that they can participate in the initiation and the perpetuation of the inflammatory response that takes place in the airway of asthmatic subjects. The general aim of this work was to investigate the role of ASMC in the pathogenesis of asthma. More specifically, we studied the expression of two C-C chemokine receptors, CCR3 and CCR1 in the context of asthma. / For the first time, this work describes the expression of chemokine receptors by ASMC. We have shown that eotaxin, an important chemokine in asthma, induces migration of ASMC through the activation of CCR3. Although CCR3 expression is not regulated by Th2 cytokines in vitro, ASMC isolated from asthmatic patients expressed intrinsically higher levels of the surface receptor when compared to controls. We also describe the expression of CCR1 by ASMC, a receptor involved in airway remodelling in an animal model of asthma. We reported the expression of CCR1 mRNA in biopsies obtained from mild, moderate and severe asthmatics and showed that mild group express the highest level of CCR1. We also confirmed that ASMC express the receptor in vivo and showed that stimulation of this receptor with its ligands induces intra-cellular calcium mobilization, which confirms its functionality. Regulation of CCR1 on ASMC was also assessed using proinflammatory, Th1 and Th2 cytokines. We found that TNF-alpha and to a lesser extent, IFN-gamma, upregulated CCR1 mRNA and protein expression, while Th2 cytokines had no effect. The effect of these two cytokines was totally suppressed by either dexamethasone or mithramycin. / Collectively, our results demonstrate the expression of functional C-C chemokine receptors by ASMC. Interestingly, we have shown that CCR3 activation mediates ASMC migration and provides a new possible mechanism for the increased smooth muscle mass observed in asthmatic patients. Although the exact function of the CCR1 expressed by ASMC is unknown, our results suggest an involvement in asthma pathogenesis, possibly through airway remodelling.

No description available.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Allergic asthma is an immunological disease, mediated by CD4+ Th2 cells, and its prevalence has increased over recent decades. Features of allergic asthma include airway hyperresponsiveness (AHR), airway eosinophilia, excessive airway mucus production, and increased IgE and Th2 cytokine levels. Airway remodeling with pulmonary fibrosis is noted in the progress of asthma. In this thesis, a murine model of allergic asthma was used to investigate the effect of cyclophosphamide (CY) on asthma and the involvement of regulatory T cells (Treg), and the role of Granulocyte-macrophage colony stimulating-factor (GM-CSF) in allergic asthma by using GM-CSF knockout mice. CY is a cytotoxic agent, which paradoxically augments several immune responses. The first part of this thesis was aimed to study the effects of CY in a murine model of allergic airway inflammation. BALB/c mice were immunized with ovalbumin (OVA) on days 0 and 14, and challenged with aerosolized OVA from days 21 to 27. Some mice additionally received CY on days -2 and 12. In the CY-treated animals, pronounced worsening of inflammatory features was noted, including increases in eosinophil infiltration, epithelial thickness, mucus occlusion and eosinophil numbers in bronchoalveolar lavage fluid (BALF). Increased total and OVA-specific serum IgE were also noted in the CY-treated animals. In cell cultures from peritracheal lymph nodes, the Th2 cytokines IL-4 and IL-5 were elevated in animals treated with CY. It was hypothesized that the effects of CY could be caused by reduced immunosuppression mediated by Treg. mRNA expression of the immunosuppressive cytokines IL-10 and TGF-beta was reduced in the lungs of CY-treated mice. The expression of FoxP3, a marker of naturally occurring Treg, was significantly reduced in spleens, thymuses and peritracheal lymph nodes after the second injection of CY, and in the lung tissue after allergen challenge in CY-treated mice. Furthermore, lung IL-10-producing CD4+ T cells and CTLA-4+-bearing CD4+ T cells were reduced after allergen aerosol challenge in CY-treated mice. Thus CY worsened the features of allergic pulmonary inflammation in this model, in association with increased production of IgE and Th2 cytokines. The reduction in expression of FoxP3 and immunosuppressive cytokines by CY suggests that toxicity to Treg may contribute to the increased inflammation. GM-CSF plays a role in the growth, development, and maturation of bone marrow hemopoietic cells into mature blood cells, and has been proposed to be involved in potentiating the function of inflammatory cells in allergic inflammation. In the second part of this thesis, GM-CSF knockout (KO) mice were used to investigate the role of GM-CSF. In allergic KO mice, airway eosinophils were only shown in the perivascular, but not peribronchial areas in the lung, compared to the allergic wild-type (WT) mice in which eosinophil infiltration appeared in both areas. Eosinophil numbers were drastically reduced in the bronchoalveolar lavage fluid (BALF) of KO mice. IL-5 production in the lung tissue and BALF in allergic KO mice was reduced; similar results were also found in peritracheal draining lymph nodes after in vitro stimulation assays. However, IL-4 and IL-13 production, airway hyperresponsiveness (AHR), and serum IgE production were not affected in allergic KO mice. Surprisingly, lung IFN-gamma mRNA and BALF levels were increased in allergic KO mice. Lung mRNA levels of CCR3, a key chemokine receptor on eosinophils, were significantly reduced in allergic KO mice, whereas expression of the chemokines eotaxin and RANTES were at similar levels in allergic KO and WT mice. Lung mRNA levels of the IFN-gamma-inducible chemokines Mig (CXCL9) and IP-10 (CXCL10), which are antagonists of CCR3, and their receptor CXCR3 were increased in allergic KO mice, compared with allergic WT mice. Data obtained from flow cytometry showed more eosinophils survived in the lung of WT mice than KO mice. Another allergy model, a peritoneal allergy model was performed to investigate inflammation in a different model. Leukocyte subpopulations such as neutrophils, eosinophils, macrophages, and lymphocytes were reduced in the peritoneal lavage fluid of allergic KO mice. The findings revealed that GM-CSF is essential for IL-5 production, pulmonary airway eosinophilia and eosinophil survival. In the absence of GM-CSF, over-production of IFN-???? may induce chemokines, including Mig and IP-10, which are antagonists for CCR3 and may reduce airway eosinophil infiltration. In this thesis, a murine model of allergic asthma has been used to obtain novel findings on the regulation of allergic inflammation. The results with CY are relevant to the treatment of asthma patients with CY and other cytotoxic agents. The findings in the GM-CSF KO mice suggest that GM-CSF is a potential therapeutic target in asthma, and that in assessment of new therapeutic agents for asthma, effects on GM-CSF should be considered.