Mike the Mad Biologist

Nematodes and Crohn’s Disease?

When I was taking invertebrate zoology, my teacher remarked that if you got rid of all multicellular organisms, and replaced nematodes (tiny little, multicellular worms) with points of lights, you would see the outline of every multicellular organism on the planet. Since nematodes are everywhere, it’s surprising that the role of nematodes in the maintenance of ‘normal’ health hasn’t been well investigated. So this NY Times magazine article about nematodes and Crohn’s disease fascinating (all the more so since I just helped submit a proposal to study the effects of the microbiome on inflammatory bowel disease):

The prevalence of inflammatory bowel disease (I.B.D.) across North America increased markedly during the 20th century. Many thought that “bad” genes would eventually explain the spike, but Weinstock didn’t buy it. In areas where fewer than two generations ago the I.B.D. incidence might have been as low as 1 in 10,000, it was now 1 in 250. A defective gene couldn’t spread that quickly, he reasoned. It had to be something in the environment. But what? Stumped, Weinstock tried turning the question around. Instead of asking what triggered I.B.D., he asked what, before the 20th century, protected against it?

…These worms, or helminths, have a paradoxical effect on the host. Rather than induce inflammation, which is the body’s typical response to invasion, the intruders calm the host immune system. They force a peace, scientists think, to avoid eviction and keep the host–their home and food source–as healthy as possible. As Weinstock considered the I.B.D. puzzle, he wondered if immune manipulation by worms could incidentally protect against other diseases.

Comparison of the prevalence of I.B.D. and surveys of worm-infestation rates revealed a telling pattern. About 10 years after improved hygiene and deworming efforts reduced worms in a given population, I.B.D. rates jumped. Weinstock had his hypothesis: after a long coevolution, the human immune system came to depend on the worms for proper functioning. When cleaner conditions and new medicines evicted the worms from our bodies, the immune system went out of kilter.

The NY Times also has a related article on worms and allergies.

Comments

  1. #1 Left_Wing_Fox
    July 3, 2008

    Ironic.

    The Death knell of “Woo” for me was my brother’s battle with Crohn’s Disease. Before the doctors finally tracked down his ailment, we tried an “alternative” practitioner, who confidently declared the problem to be “Parasites” , and prescribed large doses of ground cloves in pill form. Years later, I would run into a co-worker who was also eating diets prescribed by herbalists to combat these unspecified “Parasites”.

  2. #2 caynazzo
    July 3, 2008

    What’s a “genetic cell”? Sounds an a lot like germ cell, but that’s not likely. In any event what a tortured last few sentences.

  3. #3 Gabe
    July 4, 2008

    Interesting. I remember watching Discovery Channel quite a few years ago and in one of those random “future research” shows they were talking about a new research on how sterile nematodes implanted in patients helped in the control of extreme colon pain (probably Crohn). It seems these worms do indeed need some extra love in some serious research labs.

  4. #4 Django
    July 10, 2008

    “Genetic cell”? I took that to mean a cell with ‘Your’ genes, as opposed to all the other cells with bacterial, nematode,etc genes that also make up “You”. A neat idea – we are our own little Gaias…

  5. #5 Adam
    August 6, 2008

    Big thanks for info