Common gut compound may be key to preventing and treating bronchiolitis in babies

A potentially groundbreaking discovery demonstrates that human gut bacteria may contain a compound that minimizes the harmful effects of respiratory syncytial virus (RSV). RSV is an important cause of lower respiratory infections in children 2 and under, specifically bronchiolitis.

Brazilian researchers conducted this work as an extension of four previous projects. Before, the researchers used various strategies to alter the gut environment in mice, generally by administering antibiotics or increasing the fiber in their diets. Afterwards, they’d test their responses to RSV. However, there was a significant limitation in their past work that they wanted to address in the latest work. The tests used synthetic, lab-grown RSV that isn’t seen in humans. This time around, they collected samples of the virus from two children treated at a local hospital.

A significant finding from earlier studies showed that acetate, a short-chain fatty acid derived from gut bacteria, protected mice against RSV and mitigated disease severity in those infected. Taking this into account, the viral samples from the children were inoculated into mice.

Once infected, the mice received acetate. Even with live samples, the acetate demonstrated positive effects. There was a 93% reduction in viral load and mitigation of airway inflammation.

Although pivotal, these experiments were conducted in mice and the researchers wanted to take it further by recruiting human infants suffering from the virus. “This type of study points to a correlation but doesn’t guarantee that it’s one of cause and effect,” says Marco Aurélio Ramirez Vinolo, penultimate author of the article and a co-principal investigator for the study.

To account for this, the team took it a step further and analyzed the gut bacteria and amount of short-chain fatty acids through stool samples from 17 infants. Through cross-tabulation, they found consistent results that children with bronchiolitis that had higher acetate levels suffered from less severe disease.

Vinolo believes that their series has enough supporting evidence to begin clinical trials that can verify the safety and efficacy of acetate utilization in prevention and treatment of bronchiolitis.  “We’ve been planning this for some years, but the pandemic has been an obstacle. We aim to complete the first trial in 2022, possibly with intranasal treatment,” he says.

Further, Vinolo states that their work shows that a balanced diet with plenty of fiber for gut health and immunity can’t hurt. “We don’t yet know whether eating habits can induce acetate production by gut microbiota sufficiently to protect human infants, but the possibility has been demonstrated in laboratory animals.”

This study is published in the journal eBioMedicine.

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