Later On

A blog written for those whose interests more or less match mine.

Rise in allergies linked to our war on bacteria

leave a comment »

Interesting note by Diana Gitig of Ars Technica:

“Allergic diseases have reached pandemic levels,” begins David Artis’s new paper in Nature Medicine. Artis goes on to say that, while everyone knows allergies are caused by a combination of factors involving both nature and nurture, that knowledge doesn’t help us identify what is culpable — it is not at all clear exactly what is involved, or how the relevant players promote allergic responses.

arstechnica

There is some evidence that one of the causes lies within our guts. Epidemiological studies have linked changes in the species present in commensal bacteria — the trillions of microorganisms that reside in our colon — to the development of allergic diseases. (Typically, somewhere between 1,000 and 15,000 different bacterial species inhabit our guts.) And immunologists know that signaling molecules produced by some immune cells mediate allergic inflammation.

 

Animal studies have provided the link between these two, showing that commensal bacteria promote allergic inflammation. But these researchers wanted to know more about how.

To figure it out, Artis and his colleagues at Penn’s School of Veterinary Medicine treated mice with a broad range of oral antibiotics to diminish or deplete their commensal bacteria and then examined different immunological parameters. They used a combination of five different antibiotics, ranging from ampicillin, which is fairly run of the mill, to vancomycin, which is kind of a nasty one.

They found that mice treated with antibiotics had elevated levels of antibodies known to be important in allergies and asthma (IgE class antibodies). The elevated antibodies in turn increased the levels of basophils, immune cells that play a role in inflammation, both allergic and otherwise.

This connection doesn’t only apply to mice but also to humans who have high levels of IgE for genetic reasons. People with genetically elevated levels of IgE are hypersusceptible to eczema and infections, and antibodies that neutralize IgE are used to treat asthma.

The antibiotic treatments and IgE did not act by promoting the survival of mature basophils, but rather by promoting the proliferation of basophil precursor cells in the bone marrow. Commensal bacteria limit this proliferative capacity.

That discovery is the real insight contributed by this paper. It has been well known for some time that . . .

Continue reading.

Here’s another brief note (from The Scientist) on the topic. I almost blogged this some days ago, with the idea that people (especially Americans?) who are culturally inclined to admire Rugged Individualism—the person who is entire unto him/herself, independent of others and not requiring help—tend to see the individual as remarkably separate (despite the fact that the individual’s clothing, food, shelter, knowledge, and language all come from other people, and all of us (save for some hypothetical handful) live interdependently with our fellows. In particular, as the note suggests, our own bodily processes cannot operate properly without the incorporation and cooperation of microbes that are not really a part of us but live in us and are essential to our health.

The line between us and our environment is very fuzzy indeed: we and our environment merge into each other.

Written by LeisureGuy

29 March 2012 at 8:45 am

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.