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慢性阻塞性肺疾病(COPD)的两种类型，是美国发病率和死亡率的重要原因。吸烟者死于COPD的死亡率更高，许多研究结果表明维生素A营养状况可能与COPD和终生吸烟有关。维生素A及其活性代谢物维甲酸(RA)对包括肺在内的许多组织/器官的生长和分化具有重要作用。已知RA能有效促进木瓜酶诱导的犬肺气肿和成年大鼠弹性酶诱导的肺气肿的肺泡化。我们早些时候已经报道，在我们的豚鼠模型中，香烟烟雾暴露导致肺中视黄醇的积聚和RA的减少，这表明维甲酸代谢和信号转导发生了异常。我们最近获得了来自肺组织研究联盟(LTRC)的COPD肺标本中一些维甲酸作用介质的蛋白水平和表达的初步数据。免疫印迹结果显示LRAT、CRBP-I、CRABP-II、CYP26A1、RAR1、RAR2、RAR3和RXR1的蛋白水平在轻、中、重度肺气肿之间存在差异。免疫组织化学结果显示，LRAT、CRBP-1、CRABP-II和RAR2染色在这些标本之间存在差异。微阵列数据还显示，RDH10、RDH12、RDH13、RALDH1、RALDH2、CRABP-II、CYP26A1、RAR-1、RAR-2、RAR3和RXR-1在这些标本中的表达存在差异。利用来自人类COPD研究的微阵列数据挖掘现有的GEO数据集，发现CRBP-1和RAR-3的表达随着疾病状态的不同而存在差异。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，可能会抑制正常修复。本研究的目的是建立肺气肿的严重程度与上述基因以及STRA6(最近被发现负责细胞内化视黄醇)和RAR2亚型，特别是RAR22的表达水平之间的关系，因为它的表达与COPD相关的肺癌的发展呈负相关。CRBP、LRAT、STRA6、CRABP-II(人)、RAR-2和CYP26A1由RA直接诱导。慢性阻塞性肺疾病轻、中、重度肺气肿患者的固定和冰冻肺组织已从LTRC获得，用于初步研究。在拟议的研究中，来自COPD患者的样本将进行年龄匹配，并分为两组：吸烟者和不吸烟者。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、蛋白质印迹分析、实时聚合酶链式反应和微阵列。如果成功地确定维生素A作用介质的基因表达与COPD之间存在关系，这将有助于我们设计针对其中一些基因的潜在治疗药物，或提供/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的关系。(摘要结束)

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)