A recent study published in the July issue of the Journal of Immunology helps explain why some humans contract bacterial super-infections like pneumonia with influenza. The research was led by Le Bonheur Pediatrician-in-Chief Jon McCullers, MD – an infectious disease specialist who is also chair of the Department of Pediatrics for the University of Tennessee Health Science Center and adjunct faculty at St. Jude Children's Research Hospital.
"It's been known that the influenza virus does something to suppress host immune function, which can facilitate development of deadly secondary bacterial pneumonias," said McCullers. "But we haven't known what that was or why it happens."
McCullers' research – conducted at his National Institutes of Health-funded laboratory at St. Jude Children's Research Hospital by UTHSC graduate student Hazem Ghoneim, a PhD candidate -- used advanced techniques to differentiate types of alveolar macrophages found in the lungs and airways. Researchers found that of the three types identified, only one is truly capable of fending off secondary bacterial infection. This population of macrophages, labeled the resident alveolar macrophages, is depleted during a flu infection.
"We found that influenza is specifically killing these true alveolar macrophages," said McCullers. "The window of time someone is susceptible to secondary infections corresponds with the time it takes for the other two types of alveolar macrophages to differentiate so they are then able to fight off the infection."
McCullers says his study is a step toward developing strategies for treatment.
"This discovery provides a roadmap for developing immunotherapies that can supplement the natural defenses of our body when they are at their weakest. Influenza and pneumonia are the seventh leading cause of death in the U.S., and we desperately need research such as this to improve our armamentarium," said McCullers.
About Le Bonheur Children's Hospital
Le Bonheur Children's Hospital in Memphis, Tenn., treats more than 250,000 children each year in a 255-bed hospital that features state-of-the-art technology and family-friendly resources. Nationally recognized, Le Bonheur is ranked by U.S. News & World Report as a Best Children's Hospital. Serving as a primary teaching affiliate for the University Tennessee Health Science Center, the hospital trains more pediatricians than any other hospital in the state. For more information, please call (901) 287-6030 or visit lebonheur.org. Follow us on Twitter at twitter.com/lebonheurchild or like us at Facebook at facebook.com/lebonheurchildrens.
About the University of Tennessee Health Science Center
As Tennessee's only public, statewide academic health system, the mission of the University of Tennessee Health Science Center is to bring the benefits of the health sciences to the achievement and maintenance of human health, with a focus on the citizens of Tennessee and the region, by pursuing an integrated program of education, research, clinical care, and public service. Founded in 1911, during its more than 100 years, UT Health Science Center has educated and trained more than 56,000 health care professionals in academic settings and health care facilities across the state. For more information, visit http://www.uthsc.edu.
Journal
The Journal of Immunology