U of M Researchers Discover Thyroid Hormone Speeds Clearance of Lung Edema Fluid

MINNEAPOLIS / ST. PAUL (September 30, 2008) — A recent study conducted by researchers at the University of Minnesota Medical School and the Center for Lung Science and Health demonstrated that thyroid hormone (T3) rapidly facilitates the removal of fluid that can flood the airspaces of the lung.  This new use of the hormone holds particular promise for patients suffering from pulmonary edema that occurs in association with heart failure and with acute lung injury or acute respiratory distress syndrome, a life-threatening condition for which there is no current established treatment.

In pulmonary edema, the tiny air sacs of the lung become flooded with excess fluid and are unable to carry out their critical function of gas exchange.  Ongoing fluid accumulation can result in shortness of breath, low oxygen levels and ultimately respiratory failure. Maneesh Bhargava, M.D. and David Ingbar, M.D., and colleagues, at the University of Minnesota Center for Lung Science and Health, demonstrated for the first time that thyroid hormones can act directly in a novel fashion in the lung to rapidly clear excess fluid from the air spaces. This new application for this well-studied thyroid hormone was carried out in an animal model of acute lung injury. The findings suggest the potential that aerosolized or inhaled thyroid hormone could be used as a treatment for heart failure, lung injury and premature lung disease.  

A non-lethal model of acute lung injury and edema was established by exposing rats to a high concentration of oxygen (hyperoxia, 95 percent oxygen) for 60 hours; a separate group of control rats were exposed to room air which contains only about 21 percent oxygen. Although the hyperoxia caused the disruption of the air sacs’ cell barriers and an influx of fluid, the researchers were able to demonstrate that the cell’s receptors for the thyroid hormone were not affected. When thyroid hormone was directly delivered to the air spaces of injured rat lungs, the edema fluid, which accumulated in response to injury, returned to nearly normal levels. 

This study, funded by support from the Cargill Pulmonary Research Fund of the Minnesota Medical Foundation, the National Institute of Heart, Lung, and Blood Institute, the University of Minnesota Academic Health Center, and the Will Rogers Institute, demonstrated that T3 thyroid hormone could rapidly reverse fluid accumulation in injured rat lungs if delivered directly to the air spaces.  T3’s rapid and direct effect on augmenting edema clearance in injured rat lungs suggests that further studies are warranted to evaluate its potential in human subjects as a possible strategy for treating critically ill patients with lung edema.

The Center for Lung Science and Health, an interdisciplinary center affiliated with the University of Minnesota Medical School, facilitates interdisciplinary research, education, and outreach activities in order to promote lung health and improve care of patients with lung disease. The Center is part of the University of Minnesota Academic Health Center, one of the most comprehensive facilities for health professionals in the nation, fostering interdisciplinary study, research, and education. For additional information about the Center for Lung Science and Health, visit http://www.lung.umn.edu.

Contact: Diane Kachel, Center for Lung Science and Health, 612-624-2671 or kach0034@umn.edu
Laura Stroup, Academic Health Center, 612-624-5680 or stro0481@umn.edu