Acute lung Injury (ALI) is a common cause of respiratory failure in critically ill patients. It has an incidence of ~ 200,000 cases each year in the United States alone and is associated with an unacceptably high mortality rate of 25-40% and 3.6 million hospital days in reported cases. Although, our understanding of the mechanisms relevant to the pathogenesis and the resolution of ALI and Acute Respiratory Distress Syndrome (ARDS) has increased during the past four decades, all current therapies for ALI/ARDS still rely on supportive care and no effective therapeutic options are available to improve clinical outcome. Thus, the development of new treatment strategies for ALI/ARDS that are safe, effective, and based on deeper understanding of the mechanisms involved in ALI pathogenesis is warranted. This proposal aims to clarify the cell type-specific role of MTOR (mechanistic [formerly mammalian] target of rapamycin) in ALI and test the utility of simultaneous but differential cell-specific targeting of MTOR to control ALI. The proposal is based on our published and on-going work that implicates a cell type-specific role for MTOR in inflammation; it mediates inflammation in epithelial cells whereas it serves to limit endothelial cell inflammation. Intriguingly, however, the ?net effect? of MTOR signaling results in a proinflammatory phenotype in the lung. The proposal will address the following three inter-related, but independent, aims.
Aim 1 will test the hypothesis that MTOR limits ALI by serving an anti-inflammatory function in pulmonary endothelium. Studies in this aim will ascertain the role of endothelial MTOR in moderating ALI by determining the effects of modulating MTOR signaling in pulmonary endothelium on lung inflammation and injury.
Aim 2 will investigate the possibility that MTOR promotes ALI by exerting a proinflammatory function in alveolar epithelium.
Aim 2 studies will determine the role of epithelial MTOR in augmenting ALI by monitoring the effects of modulating MTOR signaling in alveolar epithelium on lung inflammation and injury.
Aim 3 will test the hypothesis that targeting MTOR simultaneously but differentially in a cell type-specific manner (increasing it in pulmonary endothelium but decreasing it in alveolar epithelium) will yield a superior protective and therapeutic benefit against ALI. The proposed studies will be carried out using established mouse models of ALI and will utilize a very new and exciting approach that uses unique cell-specific DNA nuclear targeting sequences (DTSs) in the plasmid to direct cell-specific plasmid nuclear uptake and gene (shRNA or cDNA) expression in the desired cell type. The plasmids will be delivered into the lungs of mice via electroporation, which yields high level of gene expression without inducing inflammation or any cell damage to the epithelial or endothelial cell layer. The creative use of cell-specific DTS carrying plasmid and electroporation will provide valuable insight into the cell- specific role of MTOR in ALI and the basis for novel therapeutic approaches involving cell-specific modulation of MTOR to control ALI.
/ RELEVANCE TO PUBLIC HEALTH Acute lung Injury (ALI) is a common disease with an incidence of ~ 200,000 cases each year in the United States alone. Despite the use of state-of-the-art treatment, ALI is associated with an unacceptably high mortality rate and accounts for ~75000 deaths in the United States every year. The proposed studies are designed to gain novel insights into pathogenesis of ALI by studying the differential action of MTOR (Mechanistic Target of Rapamycin), a master regulator of cell growth and metabolism, in two very important but different cell types (endothelial vs. epithelial cells) in the lung. We will use this new information to develop a new gene therapy approach to differentially target MTOR in these cell types and evaluate its effectiveness in preventing and treating ALI in mice; this is an entirely new concept that may lead to development of novel cell- specific treatment strategies to control ALI.