An inhaled immune system stimulant protects mice against lethal pneumococcal pneumonia and other deadly bacterial, viral and fungal infections of the lungs, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reports at a major scientific meeting.
Their findings have implications for protecting immuno-compromised patients against infection and the general public against respiratory epidemics and biological weapons. The research is a featured presentation at the annual meeting of the American Society for Cell Biology Dec. 3 in Washington, D.C.
"This aerosol stimulates an innate immune system response in the lung lining fluid that kills the invading pathogens virtually on contact," says Brenton Scott, Ph.D., post-doctoral fellow in M. D. Anderson's Department of Pulmonary Medicine, and first author of the abstract presented at ASCB. "It also works in mice with suppressed immune systems."
The innate immune system is the body's inflammatory first response to infection or injury. It produces proteins and peptides that act as natural antibiotics to broadly kill invading bacteria, viruses or fungi.
"Pneumonia is a leading cause of death from infection in the United States and a major cause of death among cancer patients and others with suppressed immune systems," says Burton Dickey, M.D., professor and chair of pulmonary medicine and senior author of the research.
Untreated mice exposed to S. pneumoniae, the most common form of bacterial pneumonia, died within days. Mice treated with the Aerosolized Lung Innate Immune Stimulant (ALIIS), developed by the researchers, two hours before exposure had an 83 percent survival rate. All of the mice treated between 4 and 24 hours before exposure survived.
The effect slowly declines over five days, Scott says. Giving the stimulant after infection also provides some protection.
The team got similar results testing ALIIS as a protectant against lethal doses of several other types of pneumonia, as well as influenza virus, the mold aspergillus, and the Class A bioterror agents anthrax, bubonic plague, and tularemia.
ALIIS consists of a purified extract of a common bacterium, Haemophilus influenzae, that causes ear and sinus infections in children. The bacterium is essentially broken open, purified and administered as an aerosol.
Preclinical research continues, with early clinical trials - most likely to test a protective role in cancer patients - at least a year away.
The innate immune system indiscriminately targets invading pathogens and also recruits the adaptive immune system to launch a more targeted, pathogen-specific response. The adaptive immune system takes a few days to respond, Dickey says.