Allergies, hygiene, bugs & worms

As discussed in Chap. 7 of the book, the hygiene hypothesis suggests that reduced exposure to dirt during infancy in Western developed countries leads to increases in allergies, eczema, and possibly auto-immune disease. It is clear that these countries are facing an epidemic of allergies and even potentially lethal food allergies. It is also true that animal experiments have shown that early exposure to microbes “educates” the immune system such that it does not over-react to new stimulants, as well as microbes normally living the gut (“commensal” bacteria). The Nov. 24 issue of Nature has an up to date commentary on the hygiene hypothesis and allergies, as well as a story about attempts to use commensal bacteria such as those commonly found in yogurtto combat allergies. The bottom line is that the results of such studies are mixed at this point, but investigators remain optimistic that the right combination of commensals, genes and lifestyle may result in an effective therapy.

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The story contains several quotes from my colleague Sarkis Mazmanian, who is also cited in my book, as we are collaborating on a project on commensal bacteria in the mouse model of the autism risk factor, maternal infection.

Oh, and worms? Yes, using parasitic worms (helminths) to educate the immune system back into balance is also being tested in autoimmune disorders of several types.

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2 Responses to Allergies, hygiene, bugs & worms

  1. Thanks for the post. Regarding allergies and their ‘treatment’ with pro-, pre-biotics I do wonder if this is the the best strategy or not. Assuming that there is quite a complex communication between gut microbiota and our immune system and that our immune system might be developmentally ‘primed’ to identify ‘self-bacteria’ from not-self-bacteria based on our early exposure and what type of bacteria colonise us starting with our passage down the birth canal (assuming our journey into the world began this way), the question about whether we can truly ‘alter’ our bacterial makeup after a certain period has to be asked. Whether also the ‘right’ kind of bacteria from probiotics et al are able to actually re-colonise the right part of the gut (surviving the stomach) is another question with few answers. Dare I even mention the words: ‘bacterial transplantation’?
    As for helminth therapy, worms have been our evolutionary friends/enemies for quite a long time. The effect of our erradication of these symbiotic creatures as part of our shiny, sanitised lifestyles is perhaps only just starting to be realised.

    • phpatterson says:

      Excellent points Paul W. It has indeed been suggested that it is difficult to truly alter the gut microbiota by simple oral application of bacteria. We are currently experimenting with this in the mouse. It is possible that one needs to give an antibiotic first in order to clear the way. Or, it may be that a simple, acute application reorders the balance of microbiota without colonizing with the new bacteria. We hope to get good data on this soon. This is why using germ-free mice does not reflect the much more complex, natural situation.

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