July 6 (UPI) -- Researchers at the Natural Institutes of Health have identified a naturally occurring lipid that disease-causing bacterium use to damage a host's immune response and increase the chance of infection. The discovery may also mean a new potent inflammation therapy against bacterial and viral diseases.
Lipids, which are waxy, fatty acids, are known to help the bacteria that causes the disease tularemia. The bacteria, Francisella tularensis, uses the lipid to suppress host inflammation when infecting mouse and human cells.
In a new study, published in the Journal of Innate Immunity, researchers from NIH's National Institute of Allergy and Infectious Diseases found a form of the lipid phosphatidylethanoloamine, or PE, present in the bacterium.
The scientists considered its potential therapeutic value. Because the bacterium is extremely infectious and difficult to work with, the group developed synthetic lipids -- PE2410 and PEPC2410 -- that would be easier to study and produce.
They confirmed that the synthetic lipids also suppressed the immune response during infection of mouse and human cells in the laboratory. They then tested the natural and synthetic PE in the laboratory against dengue fever virus-infected human cells. Both versions impaired the immune response compared to the response in infected but untreated cells.
The composition of PE found in the bacterium is different from that found in other bacteria. In cell-culture experiments, the researchers found that both the natural and synthetic form of PE reduced inflammation caused by the bacteria and dengue fever virus.
Tularemia is a potentially fatal disease spread to humans by an infected animal or bites from mosquitoes, ticks or deer flies. It can be treated with antibiotics, but is difficult to diagnose because it can suppress the human immune response.
Dengue fever, which is spread by Aedes aegypti mosquitoes, is rarely fatal but leads to symptoms such as high fever, severe headache and body pain. And there is no specific treatment for it.
The researchers said they will continue exploring how F. tularensis impedes the immune response, and hope the findings will lead to a potent, broad-spectrum anti-inflammatory therapeutic.