Is Ruminococcus gnavus responsible for some childhood allergies?
A bacterial marker for intestinal dysbiosis may explain the onset of respiratory allergy episodes.
The development of childhood allergies is often associated with intestinal dysbiosis, but until now, no bacteria had been identified as the agent responsible for the disease. Taiwanese researchers have recently described a bacterium that may explain the onset of respiratory allergies in children.
Their study stands out from previous studies because the researchers analyzed the microbiota before and after the appearance of allergies (previous studies were often interested in subjects who were already sick). The researchers removed genetic and environmental biases by basing it around thirty twins, from birth to age three. They analyzed the children’s stools from birth to one year of age to characterize the microbiota. To validate their results, they also developed a parallel experimental model for asthma (mice), whom they infected with Ruminococcus gnavus to confirm that the bacterium was indeed responsible for the development of allergies, and to study the pathophysiological mechanisms. The results showed that R. gnavus, an anaerobic gram-positive bacteria from the order Clostridiales, is responsible for the onset of allergic episodes such as asthma and allergic rhinitis in the study population of children, a result that was corroborated by the animal model. The overabundance of R. gnavus seems to cause inflammation in the intestinal tract, which increases the number of lymphocytes and eosinophils that are released into blood and lymphatic circulation, and in turn causes an allergic reaction in the respiratory tract.
This discovery may allow for the future development of therapies specifically targeting this bacterium in order to limit respiratory allergy episodes in children
Chua HH et al. Intestinal Dysbiosis Featuring Abundance of Ruminococcus gnavus Associates With Allergic Diseases in Infants. Gastroenterology 2017 sept. 11. https://www.ncbi.nlm.nih.gov/pubmed/28912020