Bacteria trigger production of key immune cells

SINGAPORE (Reuters) - Allergies and autoimmune diseases such as rheumatoid arthritis could one day be prevented by consuming a type of bacteria, like probiotics taken in yogurt, according to a study published on Thursday.

The researchers fed mice with a family of bacteria and found that it triggered the production of certain white blood cells, called regulatory T cells.

"By increasing regulatory T cells, they will help suppress many of our allergies and autoimmune diseases," said one of the scientists, Kenya Honda, an immunology associate professor at the University of Tokyo.

Regulatory T cells are white blood cells that regulate the immune system and prevent it from excessive reactions.

When an immune system goes into an overdrive, it can cause allergies. It can also destroy healthy cells and tissues and cause autoimmune diseases like rheumatoid arthritis, psoriasis or scaly skin, and Crohn's disease.

Honda and colleagues, who published their findings in the journal Science, used antibiotics to flush all bacteria from the guts of a group of mice.

They later fed the rodents 46 species of harmless Clostridium bacteria and found that regulatory T cells quickly returned to their colons.

"The 46 strains were isolated from healthy, conventionally reared mice," Honda said by telephone. "And the strains were sufficient for the induction of regulatory T cells in their colons."

The researchers next fed the bacteria to normal mice and found that it produced elevated levels of regulatory T cells in their colons. These normal mice were also able to ward off some allergies and colitis, an autoimmune disease, Honda said.

"We fed the clostridium species to normal, conventionally reared mice ... they had more regulatory T cells in their colons and they were resistant to colitis and other allergies," he said.

Looking ahead, Honda said experts can study the possibility of including live Clostridium bacteria in fermented foods.

"We may be able to use live Clostridium species in probiotics, like in yoghurt. If you drink Clostridium species, you may be able to increase regulatory T cells in your intestines and your allergic responses will be taken care of," he said.

Probiotics are live micro-organisms that are believed to be good for their hosts.

There are many other strains of Clostridium and some are harmful, including one that causes tetanus and the Clostridium difficile, a drug-resistant superbug. But these were not in the cocktail of bacteria given to the mice.

SOURCE: http://link.reuters.com/zup53r Science, online December 23, 2010.