stress-gut bacteria -disease

[Guest guest]

Gut reaction

Spencer Hunt

The Columbus Dispatch, Ohio

04-11-11

April 10--Doctors and scientists know that stress can lead to illness. They just

don't know why.

But they are starting to understand where it all might begin.

Ohio State University researchers say they have found that stress-related

illnesses likely start in an unlikely place -- among the hordes of good and bad

bacteria that live in our guts.

There are as many as 500 species of bacteria living inside our large intestines.

With a combined population that approaches 100 trillion, these microbes help

transfer nutrients and vitamins to the body while others help break down wastes

and kill harmful food-borne bacteria.

, an OSU immunologist and animal physiologist, found that stress

in mice activates the immune system to fight off illness, even when there is no

threat.

Other researchers say 's work might be the first to demonstrate a link

between gut bacteria and the immune system. And they say it could help lead the

way to new treatments for stress-related diseases in people, including heart

disease, inflammatory bowel disease and diarrhea.

" It identifies a potential signal, or source of a signal, that's responsible for

the inflammatory stress response, " said Monika Fleshner, an integrative

physiologist at the University of Colorado and president-elect of the

Psychoneuroimmunology Research Society.

Fleshner said stress causes the human immune system to overproduce a class of

proteins called cytokines, which are linked to inflammation or swelling in body

tissues. These proteins typically emerge when the body is fighting off a

disease.

" A lot of symptoms of diseases are caused by the inflammatory response, "

said. " When we feel sick, those are cytokines signaling to the brain that you

should feel sick. "

It's unclear what health risks high concentrations of cytokines pose to people

who aren't sick but are stressed out. said some research suggests that

cytokines are a factor in heart disease and chronic inflammatory bowel disease.

's research found that stressed-out mice (aggressive mice are placed in

their cages) had high concentrations of inflammatory cytokine in their blood. In

some cases, levels of this type of cytokine were 100 times more concentrated in

stressed mice than in non-stressed mice.

Stress also altered the normal balance of gut bacteria. Colonies of clostridium,

a class of 100 species of bacteria, grew 28 percent in mice while another class,

bacteroides, shrank nearly in half.

established the link between the bacteria and the inflammatory cytokine

when he treated the mice with antibiotics.

The stressed-out mice treated with antibiotics had low concentrations of

bacteria and low levels of the inflammatory cytokine. That meant that the

changes in bacteria levels and not some other stress-related factor were

influencing cytokine production.

The research, published late last year in the journal Brain, Behavior and

Immunity, show that what happens in the gut has a direct link to health, said

Mark Lyte, a microbial endocrinologist at Texas Tech University's Health

Sciences Center.

Lyte helped design 's experiment and is a co-author of the study.

said more work needs to be done to further define how changes in gut

bacteria activate the body's immune response.

" Is it a single bacteria or a group that affect this response? " he said. " The

other thing is trying to understand which immune cells in the body are producing

these cytokines. "

Fleshner said she also will work to find answers to these questions.

" If we could understand a little more about potentially using bacteria to quiet

those inflammatory processes, we could have a whole new (treatment) strategy, "

she said.

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