Dietary DHA mitigates ozone induced pulmonary inflammation

项目摘要 假设和假说：臭氧（O3）是一种标准的空气污染物，它增加了慢性 肺部疾病。O3暴露对健康的有害影响部分是通过肺 由肺泡巨噬细胞产生细胞因子/趋化因子引发的炎症。O3诱导的炎症 在肺泡巨噬细胞中，由Toll样受体4（TLR 4）驱动，增加NF κ B B活化， 随后产生促炎细胞因子。因此，靶向TLR 4驱动的信号转导在 肺泡巨噬细胞是减轻O3诱导的肺部炎症的可行靶点。在这 应用，我们专注于调节肺泡巨噬细胞TLR 4介导的饮食的作用， O3暴露后的炎症反应。具体来说，膳食二十二碳六烯酸（DHA）， ω-3多不饱和脂肪酸，在西方饮食中消耗很少，可以防止O3- 诱发肺部炎症。基于强有力的初步数据，我们提出了中心假设 DHA通过两种不同的机制抑制和解决肺部炎症：1）结构上， 我们认为，质膜的DHA酰基链重塑了肺泡上皮细胞的大小和组成， 巨噬细胞脂筏抑制下游信号传导和细胞因子分泌; 2）生物化学，DHA 经过酶促转化为专门的促分解脂质介质（SPM）， 高效免疫溶解剂。因此，DHA衍生的SPM降低NF κ B B活化 以及促炎细胞因子/趋化因子的产生，同时促进细胞凋亡的清除。 称为“巨噬细胞增多症”。这一假设得到了初步数据的支持，表明DHA 减少小鼠O3诱导的肺部炎症，增加SPM水平，同时增加 SPM受体ALX/FPR 2的表达，并在体外重塑脂筏大小。方法： 定义DHA的结构和生化机制，我们提出了三个目标。目标1： 将证明DHA通过以下方式改善O3诱导的肺部炎症和损伤的消退： DHA补充剂和DHA缺乏小鼠的使用。在目标2中，我们将建立机制， DHA通过其重塑肺泡巨噬细胞脂筏的生物物理结构， 使用最先进的定量成像方法进行下游信号传导。在目标3中，我们将建立 DHA如何通过产生SPM（包括 使用ALX/FPR敲除小鼠。拟议的目标将创新性地合并吸入 毒理学、营养生物化学、膜生物物理学和免疫学。影响： 该提案的完成将：1）为临床DHA补充提供科学依据 减轻O3引起的发病率的研究; 2）提供以下方面的关键机制联系： 环境污染物暴露和饮食，将告知有针对性的治疗策略。总的来说，这 应用是高度优先考虑的，因为它为长期改善饮食奠定了基础。 对非达标空气污染区易感人群的建议，以减轻有害的 健康影响。

PROJECT SUMMARY Premise and hypothesis: Ozone (O3) is a criteria air pollutant that increases the incidence of chronic pulmonary diseases. The detrimental health effects upon O3 exposure occur in part through pulmonary inflammation initiated by alveolar macrophage production of cytokine/chemokines. O3-induced inflammation in the alveolar macrophage is driven by toll-like receptor 4 (TLR4), that increases NFB activation and subsequent production of proinflammatory cytokines. Therefore, targeting TLR4 driven signaling in alveolar macrophages is a viable target to mitigate O3-induced pulmonary inflammation. In this application, we focus on the role of diet in regulating alveolar macrophage TLR4-mediated inflammatory responses upon O3 exposure. Specifically, dietary docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid that is poorly consumed in the western diet, may protect against O3- induced pulmonary inflammation. Based on strong preliminary data, we propose the central hypothesis that DHA suppresses and resolves pulmonary inflammation through two distinct mechanisms: 1) Structurally, we propose that DHA acyl chains of the plasma membrane remodel the size and composition of alveolar macrophage lipid rafts to suppress downstream signaling and cytokine secretion; 2) Biochemically, DHA undergoes enzymatic conversion into specialized pro-resolving lipid mediators (SPM), which are highly potent immunoresolvants. As a consequence, DHA-derived SPMs decrease NFB activation and the production of proinflammatory cyto/chemokines while promoting the clearance of apoptotic cells termed ‘efferocytosis’. The hypothesis is supported by preliminary data to show that DHA decreases murine O3 induced pulmonary inflammation, augments levels of SPMs while increasing expression of the SPM receptor ALX/FPR2, and remodels lipid raft size in vitro. Approach: To define the structural and biochemical mechanisms of DHA, we propose three aims. In Aim 1, we will demonstrate that DHA improves O3-induced pulmonary inflammation and resolution of injury through the use of DHA supplementation and a DHA-deficient mouse. In Aim 2, we will establish the mechanism by which DHA remodels the biophysical structure of lipid rafts of alveolar macrophages to suppress downstream signaling using cutting-edge quantitative imaging approaches. In Aim 3, we will establish how DHA improves O3-induced pulmonary inflammation through the production of SPMs including the use of an ALX/FPR knockout mouse. The proposed aims will innovatively merge inhalation toxicology, nutritional biochemistry, membrane biophysics, and immunology. Impact: Completion of this proposal will: 1) provide the scientific rationale for clinical DHA supplementation studies mitigating O3-induced morbidity and; 2) provide key mechanistic links between environmental pollutant exposure and diet that will inform targeted therapeutic strategies. Collectively, this application is of high priority given that it sets the basis for long-term improved dietary recommendations for susceptible populations in nonattainment air pollution areas to mitigate detrimental health effects.