Researchers give knowledge on how lung microorganisms secure against attacking microbes

Overview

• Post By : Kumar Jeetendra


• Source: eLife


• Date: 09 Dec,2020

New insight on how bacteria in the lungs protect against invading pathogens has been published today in the open-access eLife journal.

The study in mice shows that a strain of lung bacteria called Lactobacillus provides a barrier against Streptococcus pneumoniae (S. pneumoniae) colonisation in animals previously infected with influenza A virus when applied therapeutically following infection. S. pneumoniae can lead to severe pneumonia especially in older patients. In light of increasing antibiotic resistance, these findings indicate that probiotics may provide an alternative treatment strategy for bacterial lung infections.

In healthy organisms,’commensal’ bacteria, which live inside the host without harming it, provide a competitive barrier against invading bacterial pathogens.

“It is already well known how commensal bacteria in the gut fight off pathogens,” explains co-first author Soner Yildiz, Postdoctoral Research Fellow at the University of Geneva, Switzerland. “But how lung bacteria such as Lactobacillus execute this role is not as clear.”

To deal with this gap, Yildiz and colleagues studied the use of lung microbiota from Pneumococcus colonization in mice. The team had previously reported that a significant amount of Lactobacillus bacteria, which are known to behave as antimicrobials and immune system modulators, exist in the lung microbiota of healthy mice. In the present study, they identified these commensal bacteria as Lactobacillus murinus (L. murinus), with further gene sequencing and microscopy showing that the bacteria are tightly associated with mouse lung tissue.

They found that L. murinus inhibited the growth of the pathogen through the release of lactic acid. “This antibacterial activity wasn’t restricted to S. pneumoniae,” states co-first author João Pereira Bonifacio Lopes, PhD student at the University of Geneva. “It also affected S. aureaus, the pathogen that can cause bloodstream, bone and joint infections, in addition to pneumonia.”

Finallythey treated mice with L. murinus following influenza A infection and found that the bacteria provided a barrier against pneumococcal colonization in the animals.

This suggests that resident commensals in the lung could be applied as probiotics to counteract lung colonization by pathogenic bacteria. However, further studies are needed before this can be explored as a potential treatment in humans. If it one day proves to be effective, the approach could improve the clinical outcomes for patients who are susceptible to respiratory tract infections.”

Mirco Schmolke, Senior Author, Group Leader, University of Geneva