Targeting Underlying Pathophysiological Mechanisms to Develop Novel Therapies for Chronic Obstructive Lung Disease

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Chronic obstructive pulmonary disease (COPD) is characterized by airflow obstruction, increased mucus production, and predisposition to recurrent lower respiratory tract infections. It affects ~5% of the US population, ranking third as a cause of mortality. This high prevalence and disease chronicity results in frequent hospitalizations, and need for lifelong therapies. In spite of this high disease burden, there have been no new FDA approved therapies in the past two decades. Chronic cigarette smoke exposure, the commonest cause of COPD, leads to increased generation of reactive oxygen species (ROS), decreased mitochondrial ability to handle these ROS, and cell death, with the latter leading to breakdown of alveolar surfaces, blebbing, and decreased pulmonary surface for adequate oxygen exchange. Cilia are tubulin-containing hair-like projections on the cell surface of epithelial cells lining the tracheobronchial tree that beat in a coordinated, metachronal wave to sweep inhaled pollutants and pathogens away from the lungs. In COPD, these cilia are sparse, stunted, and beat with lower frequencies than in healthy lungs leading to poor mucociliary clearance (MCC) and recurrent infections. Mitochondrial dysfunction due to overwhelming ROS production is also associated with defective cilia formation. Our prior work led to identification of a 12-amino acid peptide that we termed Cardiac Targeting Peptide due to its ability to transduce normal mouse heart tissue after peripheral injection. An alanine scan with sequential, single alanine substitutions led to the discovery of two alanine mutants (S7A and R11A with serine at position 7 and arginine at position 11 substituted with alanine) that instead of the heart robustly transduced lung epithelial tissue after a peripheral injection. A key player in ciliogenesis is Notch, a transcription factor that determines pluripotent Club cell fate and differentiation into mucus producing goblet cells at the expense of multi-ciliated cells. We have shown that treatment of reciliating mouse tracheal and human nasal epithelial cell cultures with 2nM DAPT (N-[N-(3,5-Difluorophenacetyl)-L- alanyl]-S-phenylglycine t-butyl ester), a small molecule Notch inhibitor, led to significant increase in degree of ciliogenesis, cilia length, and ciliary beat frequency compared to controls. In this grant, we are proposing to develop these novel lung targeting peptides as vectors to deliver a number of different ROS scavengers (Szeto-Schiller peptide, Mitotempo, reduced glutathione) to lungs of mice with smoke-induced COPD. We are also proposing to utilize DAPT in vivo in these mice to improve ciliary function with the ultimate goal of improving MCC. Our overarching goal is to target novel pathophysiological pathways in COPD by enhancing mitochondrial function and ciliogenesis to improve MCC.