Low-dose natural antimicrobial exacerbates chronic lung infection in cystic fibrosis

Respiratory failure caused by chronic lung infection with Pseudomonas aeruginosa bacteria is a common cause of death in patients with cystic fibrosis (CF), a genetic disease that is common in individuals of European descent. A study published on April 24th in PLOS Pathogens demonstrates that an antimicrobial peptide produced by human immune cells can promote mutations in the bacterium that make it more lethal. Daniel Wozniak, from The Ohio State University Wexner Medical Center, USA, and colleagues studied a process called “mucoid conversion”, which involves mutations in Pseudomonas that produce a sticky sugar coating of the bacteria which makes them more resistant to various treatments. The process is fairly well understood, and involves mutation of a particular Pseudomonas gene called mucA. Searching for factors of the human host that facilitate mucA mutation, the scientists found that specific immune system cells called polymorphonucleocytes (or neutrophils), which are present in large numbers in lung cells of patients with CF, can trigger Pseudomonas mucoid conversion, and that a specific antimicrobial factor produced by these cells called LL-37 plays a key role. At high doses, LL-37 can kill bacteria by poking large holes into their cell walls. However, at lower concentrations (which seem to mimic the situation in the lungs of CF patients), the scientists found that some LL-37 molecules can enter the bacterial cells without killing them. Once inside, LL-37 ap...
Source: Cystic Fibrosis Worldwide Blog - Category: Respiratory Medicine Authors: Tags: Research and Discovery Source Type: blogs