The goal of this study is to define the environmentally induced epigenetic marks and their impact on gene expression that result in the granulomatous lung disease, chronic beryllium disease (CBD). The study relies on the expertise and strengths of our uniquely qualified investigative team. This study will define pathogenic pathways and risk factors for CBD, the precursor to this disease (beryllium sensitization; BeS) and similar environmentally induced diseases. Exposure to an inhaled Be antigen(s) in the setting of a genetically susceptible host, initiates a Th1 immune response, with antigen presentation occurring via HLA Class II on antigen presenting cell (APC) in the context of CD4+ T cells. Subsequently, CD4+ T cells and APCs are recruited to the lung, proliferate, produce cytokines and chemokine's, and eventually form granulomas. An increased prevalence of HLA-DPB1 alleles with a glutamic acid at amino acid position 69 (E69) is found in CBD and BeS This same polymorphism may be found in up to 40% of Be exposed workers without BeS or CBD, suggesting that other susceptibility factors or forms of genetic regulation must be important in disease pathogenesis, in addition to exposure. Growing data in other immune-mediated diseases suggests that epigenetic mechanisms in combination with genetic susceptibility and environment may help explain disease risk. Epigenetic modifications determine the Th1 versus Th2 immune response through DNA methylation and histone modifications of key genes such as FOXP3, and thus impact health and disease. To date epigenetic alterations have not been explored in environmentally induced granulomatous diseases. Our preliminary data demonstrate significant genome-wide DNA methylation differences in pivotal immune response genes and networks at the site of exposure and disease, the lung, in CBD compared to BeS. Based on this information, the overarching hypothesis for this proposal is that epigenetic mechanisms impact gene expression and immune cell differentiation, ultimately impacting the risk of granulomatous lung disease. Using an integrated genomic approach we will first define epigenetic alterations (genome wide methylation) in CD4+ lung cells, with and without beryllium exposure in a case control study of CBD, BeS and normal controls. Subsequently, we will determine functional methylation alterations that impact gene transcription, information which will expand our understanding of the pathogenesis of CBD. As demethylating agents, such as 5- azacytidine (AZA) and decitabine are currently being used to treat immune mediated diseases, we will evaluate changes in validated methylation and gene expression targets treating CBD, BeS and control CD4+ lung cells with demethylating (AZA) or methylating (folic acid) agents. This study will provide data relevant to this class of agents as targets for therapy. Furthermore, the information gained from this proposal will shed light on the pathogenesis of other exposure related non-infectious granulomatous diseases, and on genome-exposure relationships, as our understanding of the epigenome grows.
The reason why some develop exposure related diseases, such as the scarring lung disease chronic beryllium disease, while others do not, and why some develop more severe forms of these diseases is not well understood. This proposal will define factors that may explain why some people get CBD, while also defining new genes important in the development of this and other similar diseases, as well as helping us understand how exposure to beryllium can change these genes and factors increasing the risk for this disease. In future studies, these factors may serve as biomarkers or predictors of disease and ultimately even targets for therapy.
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