Predicting lung disease in infants

Once thought to be sterile until after birth, the airway of an infant is actually colonized with bacteria or bacterial DNA when he is born, suggests a recent study.

The University of Alabama researchers and colleagues have found that this is true for infants born as early as 24 weeks gestation.

How microbes get into the airways and the purpose of this pre-birth colonization are still unclear, but the pattern of colonization appears to have an important link to later severe neonatal lung disease.

An early microbial imbalance, or dysbiosis, is predictive for the development of bronchopulmonary dysplasia, or BPD, a chronic lung disease of prematurity. The extremely low birth-weight, or ELBW, infants in this study had an average birth weight of 1 pound, 8 ounces.

Researchers found that the ELBW infants who went on to develop life-threatening BPD showed abnormal microbial colonization patterns at birth, as compared to pre-term infants who did not get BPD.

"Right at birth, your respiratory microbiome can possibly predict your risk for BPD," said lead investigator Charitharth Vivek Lal.

The study also suggests that the 'healthy' pattern of colonization seen in the BPD-resistant ELBW infants, with increased abundance of Lactobacillus, is protective.

"We speculate that the early airway microbiome may prime the developing pulmonary immune system, and dysbiosis in its development may set the stage for subsequent lung disease," the researchers said. "Should a disordered airway microbiome prove to be involved in the pathogenesis of disease, it will be of immediate interest to attempt to develop novel therapeutic interventions."

As for the source of the microbes, Lal and colleagues wrote, "As it is commonly believed that colonization of neonates originates in the birth canal, we were surprised to find that the airway microbiome of vaginally delivered and caesarean section-delivered neonates were similar, which suggests that the microbial DNA in the airways is probably transplacentally derived, consistent with reports that the placenta has a rich microbiome."

The researchers speculate that this transmission of bacteria or bacterial DNA to the in-utero infant could be via blood or amniotic fluid.

The study appears in the journal Scientific Reports.