Identifying and Characterizing "Corticosteroid-unresponsive" Genes in Asthma

该项目的目标是确定哮喘发病机制的新机制，以及严重疾病患者的新治疗方法。 该项目将利用小鼠过敏性哮喘模型来实现这些目标。 不同的皮质类固醇无反应基因组调节皮质类固醇治疗无效的严重哮喘的疾病严重程度。 我们假设，皮质类固醇无反应基因的鉴定可能 为疾病发病机制提供新的见解，并确定新的治疗方法 哮喘患者的治疗方法。 肺的全基因组分析 来自临床相关的屋尘螨（HDM）激发哮喘模型的转录组鉴定了载脂蛋白E（apoE）的上调表达， 尽管用皮质类固醇治疗，其仍然持续升高。 这导致鉴定出apoE LDL受体（LDLR）途径作为内源性的LDL受体通路。 哮喘中AHR和杯状细胞增生的负调节因子（载脂蛋白E通过LDL受体介导的负调节屋尘螨诱导的哮喘） 通路 Yao X，Fredriksson K，Yu ZX，Xu X，Raghavachari N，Keiden KJ，Zywicke GJ， Kwak M，Amar MJ，Remaley AT，Levine SJ. Am J Respir Crit Care Med. 2010年7月9日。 Epub before print）。 特别是，我们发现apoE由肺巨噬细胞表达，并通过LDL受体依赖性机制负调节气道高反应性和杯状细胞增生。 此外，我们发现这些作用是通过纤毛气道上皮细胞表达的LDL受体介导的。 这项对哮喘患者肺转录组的全基因组分析已经确定了额外的类固醇无反应基因，这些基因在哮喘中的作用尚不清楚。 正在进行的研究使用这些候选皮质类固醇无反应基因的靶向缺失小鼠来确定这些候选基因在哮喘发病机制中的作用。 这种方法导致肽聚糖识别蛋白1作为介导的屋尘螨诱导的哮喘的发病机制的鉴定。 HDM激发的Pglyrp 1-/-小鼠显示BALF嗜酸性粒细胞和淋巴细胞、血清IgE和粘液细胞化生减少，而与WT小鼠相比，气道高反应性没有改变。HDM攻击的Pglyrp 1-/-小鼠的肺中Th 2细胞因子减少，这反映了CD 4 + Th 2细胞数量的减少。HDM攻击的Pglyrp 1-/-小鼠的BALF和肺匀浆中C-C趋化因子也减少。此外，由来自HDM攻击的Pglyrp 1-/-小鼠的肺泡巨噬细胞分泌的CCL 17、CCL 22和CCL 24显著减少。由于炎症细胞和气道上皮细胞均表达Pglyrp 1，因此进行骨髓移植以产生嵌合小鼠并评估哪种细胞类型促进HDM诱导的气道炎症。在造血细胞而非结构细胞上缺乏Pglyrp 1的小鼠显示出HDM诱导的嗜酸性粒细胞和淋巴细胞气道炎症的减少。这表明造血细胞如肺泡巨噬细胞的Pglyrp 1表达通过上调C-C趋化因子的产生介导了HDM诱导的气道炎症，C-C趋化因子将嗜酸性粒细胞和Th 2细胞募集到肺中。这发现了一个新的先天免疫反应蛋白家族，它促进了HDM诱导的哮喘气道炎症。

This project that has the goal of identifying novel mechanisms of asthma pathogenesis, as well as new treatment approaches for patients with severe disease. The project will utilize murine models of allergic asthma to achieve these goals. Distinct sets of corticosteroid-unresponsive genes modulate disease severity in severe asthma that is refractory to corticosteroid therapy. We hypothesized that the identification of corticosteroid-unresponsive genes may provide new insights into disease pathogenesis and identify novel therapeutic approaches for asthmatic patients. Genome-wide profiling of the lung transcriptome from a clinically relevant, house dust mite (HDM) challenge model of asthma identified the up-regulated expression of apolipoprotein E (apoE), which remained persistently elevated despite treatment with corticosteroids. This lead to the identification of an apoE LDL receptor (LDLR) pathway as an endogenous negative regulator of AHR and goblet cell hyperplasia in asthma (Apolipoprotein E Negatively Regulates House Dust Mite-induced Asthma via a LDL Receptor-mediated Pathway. Yao X, Fredriksson K, Yu ZX, Xu X, Raghavachari N, Keeran KJ, Zywicke GJ, Kwak M, Amar MJ, Remaley AT, Levine SJ. Am J Respir Crit Care Med. 2010 Jul 9. Epub ahead of print). In particular, we showed that apoE is expressed by lung macrophages and negatively regulates airway hyperreactivity and goblet cell hyperplasia via a LDL receptor-dependent mechanism. Furthermore, we showed that these effects are mediated via LDL receptors that are expressed by ciliated airway epithelial cells. This genome-wide analysis of the lung transcriptome in asthma has identified additional steroid-unresponsive genes that are not known to have a role in asthma. Ongoing studies are using mice with targeted deletions in these candidate corticosteroid-unresponsive genes to define the role of these candidate genes in the pathogenesis of asthma. This approach resulted in the identification of peptidoglycan recognition protein 1 as mediating the pathogenesis of house dust mite-induced asthma. HDM-challenged Pglyrp1-/- mice showed decreases in BALF eosinophils and lymphocytes, serum IgE, and mucous cell metaplasia, whereas airway hyperresponisveness was not changed when compared to WT mice. Th2 cytokines were reduced in the lungs of HDM-challenged Pglyrp1-/- mice, which reflected a decreased number of CD4+ Th2 cells. There was also a reduction in C-C chemokines in BALF and lung homogenates from HDM-challenged Pglyrp1-/- mice. Furthermore, secretion of CCL17, CCL22 and CCL24 by alveolar macrophages from HDM-challenged Pglyrp1-/- mice was markedly reduced. Since both inflammatory cells and airway epithelial cells express Pglyrp1, bone marrow transplantation was performed to generate chimeric mice and assess which cell type promotes HDM-induced airway inflammation. Mice lacking Pglyrp1 on hematopoietic cells, not structural cells, showed a reduction in HDM-induced eosinophilic and lymphocytic airway inflammation. This showed that Pglyrp1 expression by hematopoietic cells, such as alveolar macrophages, mediates HDM-induced airway inflammation by up-regulating the production of C-C chemokines that recruit eosinophils and Th2 cells to the lung. This identified a new family of innate immune response proteins that promotes HDM-induced airway inflammation in asthma.