The risk for childhood wheeze is greatly reduced when babies collect the right bugs in their microbiome early in life, new research from two studies shows. They have gone from the hygiene hypothesis to the microbial dysbiosis hypothesis; said Christine Cole Johnson, PhD, from the Henry Ford Health System in Detroit.
“The microbes established in a baby’s first months of life from the mother are important,” she explained. The type of community that develops in a baby’s gut and skin; “affects not only asthma, but the whole immune system.”She and her colleagues looked at fecal samples from infants — members of the Wayne County Health; Environment, Allergy and Asthma Longitudinal Study (WHEALS) — taken at 1 and 6 months.
They used 16S V4 sequencing; to see whether the bacterial taxa in the gut microbiome of those infants would predict; who would have whole immune system 10 years later. Gut bacterial diversification during infancy was slower in the now 10-year-old children with allergic asthma; and immature gut communities at 6 months increased the odds that a child would have allergic asthma; t 10 years.
Previous studies have shown that the risk for asthma is lower in children raise on farms; and when a parent licks a pacifier to clean it.They are the first group to show that very early microbial gut communities; actually impact asthma outcome at the ages of 10 and 11,” Johnson reported. In fact, the odds that a 10-year-old child will have allergic asthma are elevate if he or she was born by emergency cesarean; does not have a dog, is black, and has an immature gut bacterial community.
In general, boys are more likely than girls to have asthma at a young age; however, boys often grow out of it but girls are less likely to.In the WHEALS cohort; a more mature bacterial community at 1 month and a more immature bacterial community at 6 months; were associate with allergic asthma in both boys and girls.However; the increase in allergic asthma at 10 years related to this downward trajectory in diversity was more likely to affect girls than boys. “We do not understand why,” Johnson said.
Various hypotheses include the difference in lung size in boys and girls at birth and the difference in the placenta makeup. “Boys and girls may be different much earlier on than we think,” she explained. One day, a baby’s microbiome might be predictive of asthma risk, but adequate evidence has yet to be gather to provide definite answers. “There is a lot we need to find out,” said Johnson.
The risk for wheeze is also decrease in children expose to microbes through vaginal delivery and exclusive breast-feeding, according to results from another study presented at the meeting.The first major exposure to microbes occurs when babies pass through the birth canal and acquire maternal bacteria. That could be important, said Christian Rosas-Salazar, MD, from Monroe Carell Jr. Children’s Hospital at Vanderbilt in Nashville, Tennessee.
Investigators identify recurrent wheeze in 132 of the children (9%) on multi variable logistic regression adjusted for infant’s age, sex, maternal asthma, early-life exposure to antibiotics, and secondhand smoking.The risk for recurrent wheeze decreased by about 40% in children who had been deliver vaginally and were breast-fed (adjusted odds ratio [aOR], 0.63; 95% confidence interval [CI], 0.41 – 0.98; P = .04). However, in children delivered by cesarean section, breast-feeding did not affect the risk for recurrent wheeze (aOR, 1.51; 95% CI, 0.76 – 2.98; P = .2).
This study — which took into account the duration and exclusivity of breast-feeding and examine potential underlying mechanisms of its association with wheeze. Breast milk might be responsible for feeding the gut bacteria that babies collect in the birth canal, which could be the reason that the combination of breast-feeding and vaginal delivery has a protective effect, said Johnson.
“Microbes might actually be transfer to the baby through the breast milk to feed those bacteria. It’s complex,” she explained. “We know that breast milk changes almost every day to match the needs of the baby,” but more research is need to understand the association better.