Worms use immune system to extract food from cells

February 16, 2016 by Merry R. Buckley
Trichinella spiralis newborn larvae invade skeletal muscle cells, inducing the formation of the unique cell-parasite complex called the nurse cell.

White blood cells are usually our allies in fighting infections, but new research shows that when Trichinella worms first invade muscle cells, one particular type of white blood cell doesn't attack – rather it helps the worms extract nutrients from the body, making the worms stronger and more successful.

Lead author Lu Huang says this leg up from the immune system is necessary for Trichinella to grow normally. A postdoctoral associate in the Department of Microbiology and Immunology in Cornell's College of Veterinary Medicine, Huang says these cells, called eosinophils, may play this same subversive role in many other parasitic worm infections.

"Large numbers of eosinophils flock to sites of infection in all worm infections," says Huang. "Once they're there they can promote nutrient uptake, providing a favorable environment for the worms."

This is a tactic controlled by the worm, says senior author Judy Appleton, vice provost, director of Engaged Cornell and the Alfred H. Caspary Professor of Immunology at the Baker Institute for Animal Health in the College of Veterinary Medicine. "The worm stimulates an immune response, then co-opts the immune response to help itself."

In previous work, Appleton's lab showed that eosinophils helped worms survive in the body by tamping down the production of nitric oxide (NO), a gas that the immune system produces and is toxic to Trichinella . Their follow-up work, described in the December 2015 PLOS Pathogens, revealed the eosinophils not only prevented this gas attack on Trichinella, their presence was 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.

These gifts of forbearance (withholding a gas attack) and sustenance (providing glucose) that eosinophils bestow upon are surely bad news for the infected host, but Appleton points out that this knowledge is power in the battle to end parasitic worm infections, which currently effect an estimated 2 billion people worldwide. Knowing that eosinophils may not be our allies in fighting these pathogens can push the science in the right direction, she says.

"When you vaccinate for an infectious disease, you're trying to induce a certain kind of ," she says. The dogma on eosinophils used to be that they are helpful in combatting infection, but Appleton's lab has revealed that stimulating eosinophils would likely help a parasite to survive within the host.

"Understanding the roles these blood cells can play will help in developing effective therapeutics that use the . If you boost the in a worm infection you might get a result that you don't want."

Explore further: Invading worms cause the body to shut down defenses

More information: Lu Huang et al. Eosinophils and IL-4 Support Nematode Growth Coincident with an Innate Response to Tissue Injury, PLOS Pathogens (2015). DOI: 10.1371/journal.ppat.1005347

Related Stories

Invading worms cause the body to shut down defenses

October 20, 2014

When parasitic worms invade muscle tissue, white blood cells called eosinophils rush to the scene. A study published in the Journal of Immunology this month reveals that these cells actually start a chain reaction that stops ...

Weight loss helps to oust worms

January 17, 2013

Scientists from The University of Manchester have discovered that weight loss plays an important role in the body's response to fighting off intestinal worms.

Call for help to killer cells improves cancer rejection

June 11, 2015

Sometimes it takes a long time to solve a puzzle: In 1893, German surgeon G. Reinbach discovered that tumor tissue is often infiltrated by special cells of the immune system called eosinophils. Ever since then, scientists ...

Recommended for you

Researchers reveal role of gene in IBD

April 26, 2017

Inside a healthy gut, bacteria and immune cells maintain a delicate balance. If that balance is disturbed, a condition called inflammatory bowel disease or IBD can result. Patients with IBD can experience diarrhea, abdominal ...

When liver immune cells turn bad

April 21, 2017

A high-fat diet and obesity turn "hero" virus-fighting liver immune cells "rogue", leading to insulin resistance, a condition that often results in type 2 diabetes, according to research published today in Science Immunology.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Feb 24, 2016
Help the worms? It quite surprised me. Hope further study can find solution to this.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.