Alteration In Pulmonary Immune Function /Host Resistance

我们正在研究环氧合酶在肺部对环境因素的反应中的作用。在基线时，COX-1基因缺失小鼠的肺前列腺素E_2水平低于野生型或COX-2基因缺失小鼠，但在基础肺功能或肺组织病理学方面，两种基因型之间没有显著差异。在过敏原(卵清蛋白)致敏/暴露后，COX-1基因缺失和COX-2基因缺失小鼠的肺炎症指数显著高于野生型小鼠。COX-1基因缺失小鼠呼吸道嗜酸性粒细胞数量增加，CD3+/CD4+淋巴细胞(TH细胞)数量增加。来自过敏性COX-1缺失呼吸道的肺泡巨噬细胞表现出激活的生化和形态证据。COX-1基因缺失小鼠的支气管肺泡灌洗液(BALF)中TH2细胞因子IL-4、IL-5和IL-13水平显著升高，LTB4和半胱氨基白三烯水平升高，趋化因子TARC和eoaxin水平升高。COX-1基因缺失小鼠的这些变化与BALF IgE水平升高和MUC5AC产生/粘蛋白分泌增加有关。此外，过敏性COX-1和过敏性COX-2缺失小鼠肺组织中黏附分子VCAM-1和ICAM-1的表达均增加。过敏性COX-1基因缺失的小鼠肺顺应性降低，变应原诱导的支气管收缩增加，对吸入乙酰甲胆碱表现出高反应性。我们还研究了COX基因的干扰对其他环境相关因素的肺反应的影响，包括吸入内毒素(细菌脂多糖)、五氧化二钒和流感病毒。在脂多糖暴露后，所有小鼠都表现出更强的支气管收缩和乙酰甲胆碱高反应性；然而，与野生型对照相比，COX-1缺失和COX-2缺失小鼠的这些变化要明显得多。有趣的是，在脂多糖暴露后，不同基因型的BALF细胞或肺组织病理学没有显著差异。因此，COX-1和COX-2的平衡在调节吸入性内毒素的生理性反应而不是炎症反应中起重要作用。在五氧化二钒(V2O5)暴露后，COX-2基因缺失的小鼠，而不是COX-1基因缺失的小鼠，急性肺部炎症增加，并发展成更多的肺纤维化(肺组织羟脯氨酸增加和三色染色增强)。我们还利用肺部流感传染性模型来评估宿主抵抗力，并确定COX-1基因缺失和COX-2基因缺失小鼠对病毒感染的先天或获得性免疫反应是否存在缺陷。在初步研究中，小鼠通过鼻腔途径接种适应了香港甲型流感病毒的小鼠，并跟踪治疗1周以评估免疫反应。我们发现，COX-2基因缺失的小鼠没有急性发热反应，在感染后第6天，BALF细胞和促炎细胞因子TNFa、IL-1b和干扰素-g的水平降低。与对病毒的弱化反应一致，50%的COX-2基因缺失小鼠在感染后一周内死亡，而野生型小鼠没有死亡。相反，COX-1基因缺失的小鼠在感染后第4天BALF细胞增加，TNFa和IL-1b水平增加。因此，COX基因缺陷小鼠的反应因环境刺激而异。我们最近开发出了肺特异性高表达人COX-1的转基因小鼠(小鼠CC10启动子驱动)。这些小鼠被用来确定在基线和各种环境刺激后增加的COX衍生二十烷类化合物对肺功能的影响。

We are investigating the role of cyclooxygenases in the pulmonary response to environmental agents. At baseline, lung prostaglandin E2 levels are lower in COX-1 null mice compared to either wild type or COX-2 null mice, but there are no significant differences in basal lung function or in lung histopathology between the genotypes. Following allergen (ovalbumin) sensitization/exposure, lung inflammatory indices are significantly greater in COX-1 null and COX-2 null mice compared to wild type mice. Airways of allergic COX-1 null mice have increased numbers of eosinophils and increased numbers of CD3+/CD4+ lymphocytes (TH cells). Alveolar macrophages from allergic COX-1 null airways show biochemical and morphologic evidence of activation. Bronchoalveolar lavage fluid (BALF) from allergic COX-1 null mice contains significantly higher levels of the TH2 cytokines IL-4, IL-5 and IL-13, increased levels of LTB4 and the cysteinyl leukotrienes, and increased levels of the chemokines TARC and eotaxin. These changes in the COX-1 null mice are associated with increased BALF IgE levels and increased MUC5AC production/mucin secretion. Moreover, expression of the adhesion molecules VCAM-1 and ICAM-1 are increased in the lungs of both allergic COX-1 and allergic COX-2 null mice. Allergic COX-1 null mice have reduced lung compliance, increased allergen-induced bronchoconstriction and display hyperresponsiveness to inhaled methacholine. We have also examined the effects of disruption of COX genes on the pulmonary responses to other environmentally relevant agents including inhaled endotoxin (bacterial lipopolysaccharide, LPS), vanadium pentoxide, and influenza virus. Following LPS exposure, all mice exhibit increased bronchoconstriction and methacholine hyperresponsiveness; however, these changes are much more pronounced in both the COX-1 null and COX-2 null mice relative to wild type controls. Interestingly, there are no significant differences in BALF cells or lung histopathology between the genotypes following LPS exposure. Thus, the balance of COX-1 and COX-2 is important in regulating the physiologic but not the inflammatory responses to inhaled LPS. Following vanadium pentoxide (V2O5) exposure, COX-2 null mice, but not COX-1 null mice, have increased acute lung inflammation and develop more lung fibrosis (increased lung hydroxyproline and enhanced trichrome staining). We have also utilized a pulmonary influenza infectivity model to evaluate host resistance and to determine if there are defects in innate or adaptive immune responses to viral infection in COX-1 null and COX-2 null mice. In preliminary studies, mice were treated with a mouse adapted Hong Kong influenza A virus via the intranasal route and followed for 1 week to evaluate the immune response. We found that COX-2 null mice have an absent acute febrile response, and have reduced BALF cells and levels of the proinflammatory cytokines TNFa, IL-1b and interferon-g on day 6 post-infection. Consistent with the attenuated response to the virus, 50% of COX-2 null mice die within 1 week of infection, whereas none of the wild type mice die. In contrast, COX-1 null mice have increased BALF cells and increased levels of TNFa and IL-1b on day 4 post-infection. Thus, the response of COX-deficient mice varies depending on the environmental stimulus. We have recently developed transgenic mice with lung-specific overexpression of human COX-1 (murine CC10 promoter driven). These mice are being used to determine the effect of increased COX-derived eicosanoids on lung function at baseline and after various environmental stimuli.