Helminths and Inflammatory Bowel Disease: Another Mechanism of Action

Earlier this week, I was looking through old stories in the mainstream media about using helminths therapeutically, and came across a truly excellent one (along with loads of garbage) that I had forgotten about.  It appeared in 2010, in Scientific American, and recounts the story of a man with ulcerative colitis who achieved remission using Trichuris trichuria (human whip worms).[i]  This is the single best documented case study in the medical literature.[ii]

I was particularly excited about re-discovering this one, as I was reminded of yet another astounding finding regarding helminths, apart from their direct anti-inflammatory effect and their positive effect on the bacterial microbiome.

In following the man’s case, the doctors found that as his colony of TTO died off, his symptoms flared.  During one such flare up, they found that “…immune cells in tissues with active colitis produced large quantities of an inflammatory signaling molecule named interluekin-17 (IL-17), but very little IL-22, the latter of which has been linked to wound healing and mucus production. When worms recolonized the colon, however, immune cells began manufacturing much more IL-22. Blood profiling and genetic analysis further revealed that tissues in which helminths thrived increased carbohydrate metabolism—a prerequisite for mucus production.”  (UC is associated with decreased mucus production.)

The presence of helminths causes immune cells to produce more of a molecule that leads to wound healing?!  That’s just amazing!  How it had slipped my mind, I don’t know.

Dr. P’ng Loke (one of my favorite researchers, who I have mentioned before), the lead author of the published case study, hypothesizes that “…the mucus serves as a defensive barrier between bacteria and the gut that prevents bacteria from causing inflammation and crossing over into other tissues.”

Dr. Loke was apparently stunned by his findings.  The article in Scientific American concludes with this quote, as will I: “When I first sat down to lunch with the guy who called me and he started telling me his story, I was really quite skeptical…But now I am completely changing my mind about helminthic therapy.”

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[i] https://www.scientificamerican.com/article/helminthic-therapy-mucus/

[ii] M. J. Broadhurst, J. M. Leung, V. Kashyap, J. M. McCune, U. Mahadevan, J. H. McKerrow, P. Loke, IL-22⁺ CD4⁺ T Cells Are Associated with Therapeutic Trichuris trichiura Infection in an Ulcerative Colitis Patient Sci. Transl. Med. 2, 60ra88 (2010).