Researchers have discovered how a common bacterium manipulates the human immune system during respiratory infections, leading to persistent illness.
A team from The University of Queensland identified how this bacterium impacts the immune system.
Professor Ulrike Kappler from UQ’s School of Chemical and Molecular Biosciences led the study on Haemophilus influenzae, a bacterium known to worsen respiratory infections.
“These bacteria can be particularly harmful to vulnerable populations like individuals with cystic fibrosis, asthma, the elderly, and Indigenous communities,” explained Professor Kappler.
“They can significantly exacerbate symptoms in conditions such as asthma and chronic obstructive pulmonary disease.”
The study revealed that the bacterium persists by dampening the body’s immune responses, effectively inducing tolerance in human respiratory tissues.
According to Professor Kappler, Haemophilus influenzae has the unique ability to communicate with and disable the immune system, tricking it into perceiving no threat.
The researchers simulated human nasal tissue in the laboratory to mimic the respiratory tract and observed gene expression changes over a simulated 14-day infection.
They noticed minimal production of inflammation molecules over time, a stark contrast to the typical rapid response of human cells to bacterial infections.
“When we exposed the tissue to both live and dead Haemophilus influenzae, the dead bacteria triggered a swift inflammation response, while the live bacteria prevented this reaction,” Professor Kappler explained.
“This demonstrated the bacterium’s ability to actively suppress the human immune system.”
Co-author and paediatric respiratory physician Emeritus Professor Peter Sly from UQ’s Faculty of Medicine highlighted how Haemophilus influenzae can establish chronic infections by residing within respiratory tract surface cells.
“This behavior sets it apart from many other bacteria,” noted Emeritus Professor Sly.
“If the local immunity weakens, such as during a viral infection, the bacteria may capitalize on the opportunity to cause a more severe infection.”
This discovery paves the way for future research on developing treatments that empower the immune system to identify and eliminate these bacteria to prevent infections.
“We aim to explore treatments that enhance the immune system’s capacity to detect and eradicate the pathogen before it inflicts further harm,” Professor Kappler stated.
The study findings were published in PLOS Pathogens.
