Healthy gut may be protective against atopic wheeze in kids

An analysis using data from the Barwon Infant Study (BIS) revealed that a more mature infant gut microbiota in late infancy may protect against the development of atopic wheeze in early childhood.

“Our [study] showed that a more mature gut microbiota at 1 year of age was associated with a lower chance of developing food allergies and asthma in childhood,” said Dr Yuan Gao from Deakin University, Geelong, Australia, at ERS 2023. “This appeared to be driven by the overall composition of the gut microbiota rather than specific bacteria.”

The researchers analysed faecal samples collected from BIS participants (n=1,074) at 1 month, 6 months, and a year after birth. Atopic wheeze at 1 year and 4 years was ascertained from parent-reported wheeze in the next 12 months, plus skin prick testing. In a randomly selected subset (n=323), microbiota-by-age z-scores (MAZ) at each timepoint were estimated with infant faecal amplicon sequence variants to represent microbial maturation in the first year of life. [ERS 2023, abstract OA1434]

The odds of atopic wheeze were halved at both 1 year (odds ratio [OR], 0.51; p<0.001) and 4 years of age (OR, 0.52; p=0.014) with each standard deviation increase in MAZ at 1 year of age. “[These imply that] the more mature the gut microbiota, the less likely the children were to have allergy-related wheeze,” Gao said.

It is unclear how mature gut microbiota contributes to the prevention of allergy-related illnesses. But given the complex origins and development of the gut microbiota and infant immune system, the protective effect of a healthy gut microbiome could have been due to bacterial communities acting in multiple different ways rather than via one specific mechanism, Gao noted.

Finding new ways to boost gut microbiome maturation

“With so little known about why babies develop allergies and asthma, more research is needed … We hope that by understanding how the gut microbiota improves the immune system, new ways of preventing allergy-related disease such as asthma can be developed,” Gao said.

Gao shared the team’s plans of recruiting children for a new study (ARROW) to ascertain the protective effect of dead bacteria against wheezing illnesses or asthma. These bacteria are to be administered orally in hopes of boosting a healthy immune response to viral infections.

“If we can find ways to boost the maturity of gut microbiota, this could have a significant effect on the incidence of allergies … It will be interesting to see the results from ARROW,” commented Dr Erol Gaillard, Secretary of the ERS group on paediatric allergy and asthma, who was unaffiliated with the study.

Less exposure to the outside may also do harm

“Allergy-related illnesses such as asthma and eczema are some of the commonest conditions affecting children,” said Gaillard. “We are not sure why this happens, but theories include smaller families where children are less exposed to several other siblings and the germs they inevitably carry, less diverse food eaten at an early age, and less exposure to farm animals in some communities.”

“[The current findings] fit with some of these other theories because exposure to a variety of bacteria from an early age is very likely if babies and children are regularly mixing with other children and animals and are exposed to a larger variety of foods,” Gaillard added.