Tuesday, June 26, 2012

Microbiome to go, please. Or, where do bugs stop and we begin?

Admittedly, I had never wondered which species make up the hundreds of trillions of microbes living on my skin, up my nose and in my gut. Don’t look down on me — you have ‘em too. A team of 200 researchers did wonder, however, and under the auspices of the Human Microbiome Project recently published a first look at the typical mix of flora inhabiting a healthy American.

Knowing what the bug mix looks like in healthy people, researchers can now watch for how the mix changes as diseases develop.

One surprise to come from the work is that disease-causing bacteria live in most of us, but our helpful bugs keep them in check. Also surprising, and a little unsettling, is the prospect that those of us with disease-causing microbiomes may one day undergo a “fecal transplant,” where a prescription sample of healthy stool from a nearby biorepository is used to restore health. This according to UAB gastroenterologist Peter Mannon, M.D., who was among the authors of the HMP’s lead microbiome article published in Nature last week.

Also fascinating to me is what promises to come out of the field in the next five years. We wrote an article about how Dr. Mannon’s work jibes that of UAB’s Casey Weaver, Ph.D. Dr. Weaver is working with the theory that humans, their bacteria, viruses and fungi have become a single super-organism. In fact, gut bacteria do most of the work of digesting human food, not the body.

It gets weirder. Dr. Weaver and others have come across evidence immune system may not have evolved to repel invaders. Instead, the system could have come about to decide which of the bugs we “invite in” are good or bad at the borders of their pen (our guts). If true, the immune system’s ability to repel invaders might be a lucky after-effect of its more ancient role — managing gut bacteria.

The problem is that evolution is sloppy. The system in place to manage bugs may be mistakenly recognizing helpful bugs as threats. If so, it could be adding to chronic inflammation, not just in Crohn’s disease or irritable bowel syndrome as expected, but also in cancer, heart disease, diabetes and obesity.

The news broke recently in a big way, with leading writers having some fun with it. Here’s a few of my favorite headlines:

In Good Health? Thank Your 100 Trillion Bacteria (New York Times, @ginakolata)

Finally, A Map Of All The Microbes On Your Body (National Public Radio, @robsteinnews)

Discover the Frenemy Within (actually a subhead, Wall Street Journal, @ronwinslow)

For the best graphic I have seen on the microbiome, check out Scientific American’s interactive feature.

Also just out, this from the Lab Rat blog at Scientific American with some serious details about how microbes help us digest food.

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