Abnormality in Gene Expression of Key Mediators of Vitamin A Action in COPD

描述（由申请人提供）： 慢性支气管炎和肺气肿是两种慢性阻塞性肺疾病（COPD），在美国是发病和死亡的重要原因。吸烟者中COPD的死亡率较高，许多研究结果表明维生素A营养状况与COPD和终生吸烟可能存在关联。维生素A及其活性代谢产物维甲酸（RA）对许多组织/器官（包括肺）的生长和分化非常重要。已知RA可有效促进木瓜蛋白酶诱导的犬肺气肿和弹性蛋白酶诱导的成年大鼠肺气肿的肺泡化。我们之前报道过，在我们的豚鼠模型中，香烟烟雾暴露引起了肺中视黄醇的积累和RA的减少，这表明类维生素A代谢和信号传导发生了异常。我们最近从肺组织研究联盟（LTRC）获得了关于COPD肺标本中维甲酸作用的一些介质的蛋白水平和表达的初步数据。蛋白质印迹数据揭示了轻度、中度和重度肺气肿之间LRAT、CRBP-I、CRABP-II、CYP 26 A1、RAR 1、RAR 2、RAR 3和RXR 1的蛋白质水平的差异。免疫组织化学数据表明这些样品之间LRAT、CRBP-1、CRABP-II和RAR 2染色的差异。微阵列数据还揭示了RDH 10、RDH 12、RDH 13、RALDH 1、RALDH 2、CRABP-II、CYP 26 A1、RAR-1、RAR-2、RAR 3和RXR-1在这些标本之间的差异表达。利用来自人类COPD研究的微阵列数据挖掘现有GEO数据集，揭示了CRBP-1和RAR-3的表达差异与疾病状态。基于上述研究，我们假设在某些类型的COPD中，维生素A作用的一些关键介质的基因表达异常，可能抑制正常修复。 本研究的目的是建立肺气肿的严重程度与上述基因以及STRA 6（最近显示负责细胞对视黄醇的内化）和RAR 2亚型（特别是RAR 22）的表达水平之间的关系，因为其表达与COPD相关的肺癌发展呈负相关。CRBP、LRAT、STRA 6、CRABP-II（人）、RAR-2和CYP 26 A1由RA直接诱导。已从LTRC获得来自患有轻度、中度和重度肺气肿的COPD患者的固定和冷冻肺组织用于初步研究。对于拟定的研究，COPD患者的标本将进行年龄匹配，并分为两组：吸烟者和非吸烟者。我们已经开发了这项研究所需的所有工具，包括免疫组织化学，Western印迹分析，实时PCR和微阵列。 如果成功地建立了维生素A作用和COPD的介质的基因表达之间的关系，它将有助于我们设计潜在的治疗药物靶向这些基因中的一些或在提供/恢复适当水平的RA。公共卫生相关性：本研究的目的是阐明COPD患者肺气肿的严重程度与肺中维甲酸作用的关键介质表达异常之间的关系。(End摘要）

DESCRIPTION (provided by applicant): Chronic bronchitis and emphysema are two kinds of chronic obstructive pulmonary disease (COPD), which are important causes of morbidity and mortality in the United States. Death rates from COPD are higher among cigarette smokers and numerous findings suggest a possible association of vitamin A nutritional status with COPD and lifetime cigarette smoking. Vitamin A and its active metabolite retinoic acid (RA) are important for growth and differentiation of many tissues/organs, including lung. RA is known to be effective in promoting alveolization in papain-induced emphysema in dogs and elastase-induced emphysema in adult rats. We have reported earlier that cigarette smoke exposure in our guinea pig model caused an accumulation of retinol and a decrease in RA in lung, suggesting an abnormality in retinoid metabolism and signaling had occurred. We have recently obtained preliminary data on the protein levels and expression of some of the mediators of retinoid action of COPD lung specimens from Lung Tissue Research Consortium (LTRC). Western blot data reveal a difference in the protein levels of LRAT, CRBP-I, CRABP-II, CYP26A1, RAR1, RAR2, RAR3, and RXR1 between mild, moderate and severe emphysema. Immunohistochemical data indicate a difference on LRAT, CRBP-1, CRABP-II and RAR2 staining between these samples. Microarray data also reveal a differential expression of RDH10, RDH12, RDH13, RALDH1, RALDH2, CRABP-II, CYP26A1, RAR-1, RAR-2, RAR3, and RXR-1 between these specimens. Mining of existing GEO datasets with microarray data from human COPD studies revealed expression differences for CRBP-1 and RAR-3 with disease state. Based on the above studies, we hypothesize that in some types of COPD, there is an abnormality in the expression of genes for some of the key mediators of vitamin A action that might inhibit normal repair. The objective of this study is to establish a relationship between the severity of emphysema and levels of expression of the above referred genes as well as STRA6 (recently shown to be responsible for internalization of retinol by the cells) and RAR2 subtypes, particularly RAR22 since its expression inversely correlates with lung cancer development associated with COPD. CRBP, LRAT, STRA6, CRABP-II (human), RAR-2, and CYP26A1 are directly induced by RA. Fixed and frozen lung tissues from COPD patients with mild, moderate and severe emphysema have been obtained from LTRC for preliminary studies. For the proposed studies, specimens from the COPD patients will be age-matched and divided into two groups: smokers and non-smokers. We have developed all of the tools required for this study, including immunohistochemistry, Western blot analysis, Real-Time PCR and microarray. If successful in establishing that there is a relationship between expression of the genes of the mediators of vitamin A action and COPD, it will help us in designing potentially therapeutic drugs targeting some of these genes or in providing/restoring appropriate levels of RA. PUBLIC HEALTH RELEVANCE: The objective of this study is to elucidate the relationship between severity of emphysema in COPD patients and abnormality in the expression of key mediators of retinoid action in lung. (End of Abstract)