Increased risk of childhood asthma development associated with specific infant airway microbiota ¹. 

By: Puck deRoos

According to the CDC the prevalence of childhood asthma has dramatically increased within the past decade, rising to become the top reason for missed school days and affecting over 6 million children in the United States alone². 

Researchers at the University of Copenhagen have found an association between an infant’s airway microbiota at one month old and the development of childhood asthma by age six. 

Previously, another factor associated with an increased risk of developing childhood asthma was delivery via cesarean section³, while living with farm animals, an older sibling, or attending day care decreased the risk of developing childhood asthma ^4,5. 

In this new study, scientists have specifically found a correlation between the presence of Veillonella (importance 28.1%), Prevotella (23.7%), and Gemella (importance 16.3%) bacteria in the airway at age one month with an increased risk of asthma development before age six. Furthermore, they analyzed the topical airway immune profile from the mucosal lining and discovered an independent correlation between the previously mentioned bacteria and the development of childhood asthma. 

At age one month, researchers found that children who developed asthma had a higher diversity of microbes, but also have an increased ratio of high-risk bacteria Vallonella and Prevotella. They found no association between specific taxa of microbes and asthma development by 6 years at ages 1 week or 3 months old. 

A larger proportion of high-risk bacteria in a critical period of airway immune development poses a major threat to normal development. The children who developed asthma early in life showed a reduction in tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), which are secreted by the bodies immune cells to fight inflammation and infections. They convergently showed an increase in Chemokine (C-C motif) ligand 2 (CCL2) and CCL17 levels in the topical immune profile. 

The airway microbiota samples were taken during the first three months of life from 700 children monitored for the development of asthma using 16S ribosomal RNA gene amplicon sequencing from the population based Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC 2010). The use of this cohort strengthened the results of the study because all children were sampled during infancy before the development of any symptoms, and were uniformly monitored for the development of any asthmatic symptoms through childhood. 

The findings of this study suggest that the development of childhood asthma may be connected to the interactions between early-life airway microbiota and the developing immune system. Because different areas of the human body have different microbial compositions which are considered healthy, determining specific microbes increasing the risk for childhood asthma may provide tools to prevent the disease’s spread.

1. Thorsen, J., Rasmussen, M.A., Waage, J. et al. Infant airway microbiota and topical immune perturbations in the origins of childhood asthma. Nat Commun 10, 5001 (2019) doi:10.1038/s41467-019-12989-7
2. The Centers for Disease Control and Prevention (CDC, 2019).
3. Thavagnanam, S., Fleming, J., Bromley, A., Shields, M. D. & Cardwell, C. R. A meta-analysis of the association between Caesarean section and childhood asthma. Clin. Exp. Allergy38, 629–633 (2008).
4. Illi, S. et al. Protection from childhood asthma and allergy in Alpine farm environments—the GABRIEL advanced studies. J. Allergy Clin. Immunol. 129, 1470–1477.e6 (2012).
5. Ball, T. M. et al. Siblings, day-care attendance, and the risk of asthma and wheezing during childhood. N. Engl. J. Med.343, 538–543 (2000).