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Missing bacteria linked with asthma

by Kurt Kleiner
Oct 9 / 15

Image above: Rothia dentocariosa, one of the bacteria missing from babies who were likely to develop asthma. Credit: Microbe World

Children who are lacking four specific kinds of gut bacteria at three months of age are much more likely to go on to develop asthma. And preliminary results suggest that inoculating them with those bacteria could protect them from developing the disease.

Brett Finlay (UBC), director of CIFAR’s new Humans & the Microbiome program, published the research with colleagues in the journal Science Translational Medicine last week. The research confirms previous suggestions that gut microbes played a role in asthma, while narrowing down the bacteria involved and the window during which they are important.

“There’s a lot of interesting evidence associating microbes with asthma. If you have antibiotics early in life you have higher rates of asthma. If you’re born by caesarean section you have higher rates of asthma. If you’re breast fed you have lower rates. We have all of these correlations with microbiota. But this is the first time anyone has shown that gut microbes early in life actually impact on asthma later in life,” Finlay says.

The researchers analyzed the microbes found in feces taken from 319 babies at three months of age. In the 22 of those who went on to develop asthma by age three, four specific types of bacteria were missing — Faecalibacterium, Lachnospira, Veillonella and Rothia, or FLVR for short.

Asthma usually results from an allergic reaction. It seems likely that one or more of the FLVR bacteria somehow assist in developing a healthy immune response that protects against asthma.

By the time they were one year old the children who would go on to develop asthma had mostly acquired the FLVR bacteria, so it seems that the bacteria need to be present during an early developmental window to have their positive effect.

Finlay and his colleagues also tested the effect of the bacteria using germ-free mice. They infected all of the mice with the complete microbiome from the feces of the children who would go on to develop asthma. Then they went ahead and exposed some of the mice to the FLVR bacteria.

The mice who did not receive the FLVR bacteria developed asthma-like symptoms, while those who received the FLVR bacteria were protected. The work suggests that in the future children at risk of asthma might be treated with probiotics to prevent it from developing.

Finlay says that the next step is to find out if all of the bacteria are needed for the protective effect, and to determine exactly what mechanism creates the protection.