Impact of Diet Induced Obesity on Acute Lung Injury

PROJECT SUMMARY Obesity afflicts 42% of the adults in the United States and is associated with significant deleterious health effects. Acute respiratory distress syndrome (ARDS) represents a final pathway of acute lung injury (ALI) arising from infectious, such as pneumonia, or sterile, such as ventilator induced lung injury, etiologies, and is associated

with high mortality. Obese patients are at increased risk of developing ARDS. This proposal addresses the critical need to better understand the mechanisms that underlie the increased susceptibility of obese patients to ARDS. We have shown in a murine model of high fat diet that obesity results in more severe ALI in sterile and infectious

models of ARDS. Obesity is characterized by increased fatty acid (FA) release that exceeds metabolic demands. Although FA are important for the physiologic regulation of a number of processes, high levels are deleterious. We have found increased free FA in the lung of obese mice after infectious and sterile ALI. FA are broken down

by means of oxidation for energy generation inside the mitochondria, whereas endogenous FA are synthesized de novo from acetyl coenzyme A. High fat diet was associated with increased lung expression of carnitine palmitoyltransferase 1a (CPT1a), an essential rate limiting enzyme for oxidation, and decreased

expression of fatty acid synthase (FASN), the enzyme catalyzing de novo FA synthesis, and of the mitochondrial fusion protein mitofusin 2 (MFN2) after ALI. Mitochondria alter size and shape via fission and fusion to meet cellular metabolic demands. Mitochondrial alterations in the alveolar epithelium have been implicated in ALI

pathogenesis. We demonstrated that depletion of FASN in alveolar epithelial type 2 cells was associated with more severe ALI and impaired mitochondrial bioenergetics. In this proposal, we hypothesize high fat diet induced downregulation of mitochondrial fusion and lipid synthesis lead to impaired mitochondrial metabolisml after injury.

Mitochondrial overload through excessive oxidation further exacerbates mitochondrial dysfunction. Aim 1 will investigate the role of FA utilization in the pathogenesis of experimental obesity induced ALI by using genetic and pharmacologic approaches to inhibit and enhance oxidation. Aim 2 will delineate the association between

FASN regulation, mitochondrial dynamics and alveolar epithelial cell type 2 dysfunction in ALI with high fat diet using genetic approaches to inhibit FASN and MFN1/2 in a sterile and infectious model of ALI. Aim 3 will characterize dysregulated metabolic pathways based on body mass index (BMI) in patients with ARDS using

plasma metabolomic profiling. These studies will provide insight into the interplay between obesity and ARDS and may uncover an unappreciated role for lipid metabolism in ALI. This proposal plays a central role in a career development plan for becoming a successful independent investigator focused on lung biology and lipid

metabolism. Weill Cornell Medicine is an ideal environment in which to execute this training plan not only because of its excellent physical resources, but also because of its intellectual community of researchers with a track record of strong mentorship of early stage investigators.