Researchers from the Asthma Research Center at Vanderbilt University Medical Center are digging further into the role of early life viral-bacterial interactions in the short- and long-term outcomes of acute respiratory infections (ARIs).
Christian Rosas-Salazar, M.D., an assistant professor of pediatrics at Monroe Carell Jr. Children’s Hospital at Vanderbilt, and colleagues reported in 2018 in the Journal of Allergy and Immunology that infants with higher amounts of Lactobacillus in their nose or upper throat during an acute respiratory syncytial virus (RSV) infection were less likely to develop childhood wheezing illnesses. “These findings provide insights into how RSV infection in infancy can cause wheezing later in life, and how the normal bacteria that live in and on us may protect us from disease,” Rosas-Salazar said.
Now, as part of an NIH-funded study, Rosas-Salazar and colleagues are examining the feasibility of modifying upper airway microbial communities, with the goal of reducing the incidence of common childhood respiratory diseases.
The Upper Airway Microbiome
While there is a strong association between early-life RSV infection and the development of asthma and other childhood wheezing illnesses, the pathways underlying the association are not fully understood.
“These findings provide insights into how the normal bacteria that live in and on us may protect us from disease.”
The upper airway bacterial microbiome has been shown to play an important role in the pathogenesis of viral ARIs. Earlier work from Rosas-Salazar and colleagues revealed that, compared to healthy infants, infants with RSV ARI have lower nasal abundances of Lactobacillus, Staphylococcus and Corynebacterium and increased nasal abundances of Haemophilus, Moraxella and Streptococcus.
More recently, Rosas-Salazar and colleagues showed that the abundance of Haemophilus was associated with multiple immune response mediators during RSV ARI in infancy.
Lactobacillus Detection
In the 2018 study, Rosas-Salazar and colleagues examined the role of the nasopharyngeal microbiome in the development of childhood wheezing illnesses following RSV by conducting a study of 118 previously healthy, term infants with confirmed RSV ARI. They collected bacteria from the infants’ noses and upper throats and monitored them until age two to assess wheezing outcomes.
Lactobacillus in the upper airway of infants with RSV ARI was associated with about 70 percent lower odds of subsequent wheeze, and about 80 percent lower odds of recurrent wheeze, at two years of age. The study was the first to report a protective effect of early life upper airway colonization with Lactobacillus on asthma-related outcomes in children.
“Detection of Lactobacillus in the upper airways of RSV-infected infants could be used to predict the later development of childhood wheezing illnesses.”
A Microbial Intervention
Rosas-Salazar says the findings point to the idea of using the detection of Lactobacillus as a biomarker and its probiotic administration to the airways as a preventative approach, which will be further investigated in the new NIH award.
“These results suggest that the detection of Lactobacillus in the upper airways of RSV-infected infants could be used to predict the later development of childhood wheezing illnesses,” Rosas-Salazar explained. “Furthermore, they open the possibility of studying the nasal administration of certain bacteria in infancy to prevent the development of these illnesses.”
