# Is Crohn's disease the result of a parasite-free environment?



## Guest (Mar 24, 2001)

I also posted this over on the Crohn's BB;I think it's a very intriguing hypothesis which needs further examination.---------------------------------------------: FASEB J 2000 Sep;14(12):1848-55 Does the failure to acquire helminthic parasites predispose to Crohn's disease?Elliott DE, Urban JF JR, Argo CK, Weinstock JVDepartment of Internal Medicine, Division of Gastroenterology/Hepatology, University of Iowa, Iowa City, Iowa 52242, USA.Two polarized patterns (Th1 and Th2) of cytokines regulate inflammatory responses. Each cytokine pattern inhibits production of the opposing pattern. Lymphocytes from inflamed intestine due to Crohn's disease secrete a Th1 pattern of cytokines. Crohn's disease is most prevalent in highly industrialized countries with temperate climates. It occurs rarely in tropical third world countries with poor sanitation. We propose that exposure to an environmental agent predisposes individuals to Crohn's disease. Parasitic worms (helminths) are common in tropical climates and in populations subject to crowding and poor sanitation. Children are most subject to helminthic colonization. Many helminths live within or migrate through the human gut where they interact with the mucosal immune system. The host mounts a mucosal response that includes Th2 cytokine production limiting helminthic colonization. Helminths and their eggs probably are the most potent stimulators of mucosal Th2 responses. The Th2 response provoked by parasitic worms can modulate immune reactions to unrelated parasitic, bacterial, and viral infections. Many people in developed countries now live in increasingly hygienic environments, avoiding exposure to helminths. Perhaps failure to acquire these parasites and experience mucosal Th2 conditioning predisposes to Crohn's disease, which is an overly active Th1 inflammation.


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## Mike NoLomotil (Jun 6, 2000)

Comment:"We propose that exposure to an environmental agent predisposes individuals to Crohn's disease. "[This is an elucidation of the "TILT" Or Toxin Induced Loss Of Tolerance postulate...which is beginning to show its merit as in vivo bowel immune studies become more common]But, unless Bengtssons recent work in Sweden using jejunal isolation can be interpreted differntly, this does not appear to be the mechanism (abscence of helminth)...at least no the sole mechanism of the aberrant mucosal response seen more prominently in western cultures. While the association is logical, and the TILT postulate is shared y more and more immunologists, this mechanism of modulation needs some scrutiny in the context of the finidngs in the research at Sahlgrens University in Sweden.perhaps as they move past the current stage of QUANTIFYING WHAT is happening they will someday go looking for WHY. But probably not until the WHAT is fully elucidated.MNL_____________ www.leapallergy.com


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## Guest (Apr 3, 2001)

More about those worms...







In the book Parasite Rex by Carl Zimmer, the author notes an interesting experiment to test the idea that Crohn's disease and related gut disorders represent an overzealous attack by the immune system to a nonexistent parasite infection. University of Iowa scientists deliberately infected seven subjects who had ulcerative colitis and Crohn's with the eggs of a parasitic worm. To quote from Zimmer: "Within a couple of weeks the eggs had hatched, the larvae had grown, and six out of the seven people went into complete remission".Hmmmmmm.....


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## Mike NoLomotil (Jun 6, 2000)

This might be intereting if they can get a large group, and use jejunal isolation AND colonic isolation techniques to quantify the mechanism. Bengtsson has reported being puzzled by an apparent "local antigen-antibody" response of the small bowel mucosa ABSENT SPECIFIC IgE to allergens PROVED to provoke a response by blind oral challenge. SO absent this, while the microvasculature reaction can sort of be explained (the cellular responses), the humoral response in absence of specific IgE could not.I agree that perhaps a "Hmmmmm...." is in order. Maybe when Bengtsson is done with ingestants he can dump some helminths into the isolated bowel sections and analyze the washings to quantify what the heck happened if he can duplicate these results.Its certainly worth asking Dr. Brostoff about, or even to ask Dr. Bengtsson. I will put it "on the list" of interesting theories/phenomena to request feedback on next time we speak and post what his/their response might be.MNL______________ www.leapallergy.com


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