Worm Therapy—an Expanding Science

When people think of worm therapy, they may cringe. I know I would, at the thought of ingesting parasite to cure a disease. However, there are some inflammatory diseases mediated by a Th1 response that scientists are beginning to try to treat with helminthic worms! Inflammatory bowel disease is one of them, but there are others.  

In humans, when in a controlled environment, worms are given to patients with IBD in juice. These worms are usually live eggs (or ova) or larvae. The patients drink the juice, and the worms travel to the gut where they mature and set up shop. The worms are thought to elicit at Th2/ Tfh response in these patients, which could control the proinflammatory Th1 response that exacerbates the symptoms of IBD. Essentially, the worms direct the immune system to switch to a Th2 response because of their antigenic properties. There’s a neat article by Summers, et al. listed below that details the procedure and mechanism of this type of treatment.

However, some patients may not be up for drinking worms. It is, after all, psychologically stressful trying to rationalize the idea of infesting yourself with a parasite that will live and grow inside of you. Speaking of growing—it may be even more stressful when thinking about the consequences of a parasitic infection that gets out of hand. So scientists have been thinking of new ways to elicit this “worm response” without actually using live worms.

Some scientists, including Y. Motomura et al., who we will discuss this week, are trying to come up with a way to administer worm antigens without having to administer the actual worm. This eliminates the worry about adverse side effects of parasitic infection, worm reproduction, and having to actually ingest the worms. The theory behind the thought is that if we can find the antigens that the body recognizes and reacts to, we can create the same Th2-driven response in patients with IBD without needing worms present in the body. To me, this sounds like a much better alternative!

What Motomura et al. did was try to see if this type of treatment would work. Because we don’t know which specific worm antigens our bodies recognize, the experimenters improvised. They blended up T. spiralis larvae and administered the worm smoothie to mice. This effectively gave the mice’s immune systems all the worm antigens to work with. Excitingly enough, some of the antigens were recognized by the mice, who produced a Th2- driven immune response against them. When Motomura et al. looked for macroscopic and microscopic/ histological markers of Chron’s Disease in the mice infected with worm antigen, they found that the macroscopic and microscopic symptoms of CD were much less severe in those mice versus the control mice.

This suggests that there may be alternative ways of delivering worm therapy, although knowing how to do so in humans is a long way off. There are still missing pieces to the puzzle, like knowing which antigens cause immune responses, what the right dosage of the antigens is, how often treatment is needed, etc. Further research will need to be done before we can know for sure. However, despite the fact that it may be a long way off, it is still exciting to know that other options are available to those who suffer from inflammatory bowel disease. 

References:

http://www.int-med.uiowa.edu/news/Stories02.asp?displayid=35

Summers RW, Elliott DE, Urban JR. JF et al. Trichuris suis therapy

in Crohn’s disease. Gut 2005; 54:87–90

Helminth antigen-based strategy ameliorate inflammation in an experimental model of colitis, Y. Motomura et al.