Researchers from National Institutes of Health (NIH) identified a natural lipid used by a disease-causing bacterium to impair the host immune response.
Naturally occurring lipids assist Francisella tularensis bacteria to suppress host inflammation and cause tularemia in mice and humans. It spreads to humans via contact with an infected animal or through the bite of a mosquito, tick or deer fly. Antibiotics are efficient against this life threatening disease. However, it is difficult to diagnose as F. tularensis bacteria can suppress the human immune response system. Although dengue fever, primarily spread by Aedes aegypti mosquitoes is rarely fatal, it progresses to high fever, severe headache and pain throughout the body. There is no specific treatment for dengue fever. The researchers from NIH’s National Institute of Allergy and Infectious Diseases found a form of the lipid phosphatidylethanoloamine, or PE that reduced inflammation caused by both tularemia bacteria and dengue fever virus as the composition of PE found in F. tularensis differs from PE found in other bacteria. The research was published in the Journal of Innate Immunity on July 03, 2018.
The researchers observed that PE impaired the immune response and stated that it can be a potential therapeutic target against inflammation. As naturally occurring F. tularensis is highly infectious and viral infections involve an unconstrained inflammatory response the team developed synthetic lipids — PE2410 and PEPC2410 to study and verified that both synthetic lipids suppressed the immune response during infection of mouse and human cells in the laboratory. Further experiments included testing natural and their synthetic PE in the laboratory against dengue fever virus-infected human cells. Both versions of PE inhibited the immune response compared to the immune response seen in infected but untreated cells. The researchers urge further exploration of impairing mechanism of F. tularensis against the immune system. The results are expected to boost development of a potent, broad-spectrum anti-inflammatory therapeutics.