As the Worm Turns: Cornell study shows Trichinella parasites turn the host’s immune system against i
Thursday, February 18, 2016
As the Worm Turns: Cornell study shows Trichinella parasites turn the host’s immune system against itself
ITHACA -- A new study from the College of Veterinary Medicine at Cornell University shows that Trichinella worms recruit their hosts’ immune systems to feed and shelter them within muscle tissue. Senior author Judy Appleton, Professor of Immunology, says the same may hold true in other parasitic worm infections: “The worm stimulates an immune response, then co-opts the immune response to help itself.” The study was described in the December 2015 PLOS Pathogens.
Trichinella infestation can lead to trichinosis, also called trichinellosis, a disease with symptoms ranging from headaches and fever to heart and breathing problems. Severe cases may end in death. Trichinella larvae are commonly found in the meat of wild and domestic animals and are able to spread when infected meat is eaten raw or undercooked.
Appleton’s research focuses on white blood cells called eosinophils, which don’t attack perceived invaders the way other white blood cells do. Eosinophils had long been perceived as helpful in combatting infection. Instead, they appear to help the worms survive. Earlier work from Appleton’s lab showed that eosinophils block the production of nitric oxide (NO), a gas produced by the immune system that is toxic to Trichinella. The follow-up study in PLOS reveals that eosinophils not only prevent the NO gas attack, their presence is actually necessary for the worm to thrive.
“We found that muscle tissue is mounting a repair response, like it would against an injury. Then the eosinophils are coming in, presumably to help with the repair, but coincidentally they help the parasite grow. We found evidence of a shift in metabolism in the muscle that would provide more glucose to the worm,” says Appleton.
This insight is useful in the battle to end parasitic worm infections, which currently affect an estimated 2 billion people worldwide, by pushing the science in the right direction.
“When you vaccinate for an infectious disease, you’re trying to induce a certain kind of immune response,” says Appleton. “Understanding the roles these blood cells can play will help in developing effective therapeutics that use the immune system.”
Cornell College of Veterinary Medicine