A novel intervention strategy for emphysema by targeting the Nrf2 pathway

Johns Hopkins University, Baltimore MD

Investigators

Linked publications, trials & patents

Abstract

[unreadable] DESCRIPTION (provided by applicant): Chronic obstructive pulmonary disease (COPD) is currently the fifth leading cause of death and affects more than 210 million people worldwide. This debilitating disease is clinically defined by irreversible airflow limitation in the lung that is primarily attributed to pulmonary emphysema and chronic bronchitis due to cigarette smoke (CS). COPD is characterized by abnormal inflammation, air space enlargement, and the loss of alveolar structure. Current treatments such as anti-inflammatories or bronchodilators are inadequate in treating COPD because they do not alter the underlying disease process and as a result do not reduce the progression of the disease. Because the prevalence of COPD is estimated to increase in the coming decades, it is imperative to identify novel therapeutic approaches to reduce the progression of COPD by targeting pathways identified to be involved in COPD pathogenesis. Our laboratory has discovered that nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), a redox-sensitive transcription factor, positively regulates the expression of genes encoding antioxidants and xenobiotic detoxification enzymes and confers cytoprotection against oxidative stress and inflammation in the lungs after exposure to cigarette smoke. Kelch-like ECH-associated protein 1 (Keapl) negatively regulates Nrf2 activity by targeting Nrf2 for proteasomal degradation under normal conditions. However, during oxidative stress (e.g. exposure to cigarette smoke) the transcription factor dissociates from its inhibitor, translocates to the nucleus and activates the expression of antioxidant and detoxifying genes. Disruption of the Nrf2 gene in mice causes greater oxidant-antioxidant imbalance and inflammation, which results in an earlier onset and more severe emphysema due to chronic cigarette smoke exposure. Therefore, we hypothesize that enhancing Nrf2 activity (by a genetic or small molecule approach) can attenuate CS-induced emphysema by decreasing oxidative stress, inflammation and apoptosis in the lung by up-regulating antioxidant and detoxifying genes. Specific Aim 1will test the hypothesis that enhancement of Nrf2 activity will reduce the progression of CS- induced emphysema using a genetic approach in a mouse model by generating conditional knockout mice in which the Keapl gene is disrupted through a tamoxifen inducible system that will lead to a global increase in Nrf2 activity. Specific Aim 2 will test the efficacy of a potent small molecule activator of Nrf2 (CDDO-Me), which will be used to intervene during the development of CS-induced emphysema in mice. The proposed translational study will provide new insights of Nrf2 pathways in the pathogenesis of COPD and aid in the development of a novel therapeutic approach for intervening in COPD. [unreadable] [unreadable] [unreadable]