New Risk for Asthma, Allergy Found

Changes in gut bacteria and fungi may increase chances of problems

THURSDAY, Dec. 23, 2004 (HealthDayNews) -- Do you have the guts to resist allergies and asthma?

A University of Michigan study says changes in the bacteria and fungi (microflora) in the gastrointestinal tract may intensify immune system response to common allergens inhaled into the lungs. This can result in an increased risk of developing chronic asthma or allergies.

"Our research indicates that microflora lining the walls of the gastrointestinal tract are a major underlying factor responsible for the immune system's ability to ignore inhaled allergens. Change the microflora in the gut and you upset the immune system's balance between tolerance and sensitization," study author Gary Huffnagle, an associate professor of internal medicine and of microbiology and immunology, said in a prepared statement.

He and a colleague tested this theory in a mouse they developed that mimics how some humans develop allergies after taking antibiotics, which can upset the balance of gut microflora.

The study appears in the January issue of Infection and Immunity.

"If lungs are repeatedly exposed to an allergen, regulatory T-cells (immune cells that can moderate immune system response) learn to recognize the allergen as not dangerous and something that can be safely ignored," Huffnagle said.

"Most researchers think that tolerance develops in the lungs, but we believe it actually occurs in the gut. When immune cells in the GI tract come in contact with swallowed allergens, that interaction triggers the development of regulatory T-cells, which then migrate to the lungs," he said.

More information

The Cleveland Clinic Foundation has more about allergies.

SOURCE: University of Michigan Health System, news release, Dec. 23, 2004
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