Bacterial Manipulation: How Haemophilus influenzae Tricks the Human Immune System
Researchers at The University of Queensland have made a groundbreaking discovery on how the common bacterium, Haemophilus influenzae, is able to manipulate the human immune system during respiratory infections, leading to persistent illness. Led by Professor Ulrike Kappler from UQ’s School of Chemical and Molecular Biosciences, the study delved into the virulence mechanisms of this bacterium known for exacerbating respiratory tract infections.
According to Professor Kappler, Haemophilus influenzae poses a significant threat to vulnerable populations such as those with cystic fibrosis, asthma, the elderly, and Indigenous communities. In conditions like asthma and chronic obstructive pulmonary disease, these bacteria can greatly worsen symptoms. The research unveiled how the bacterium evades the body’s immune responses by inducing a state of tolerance in human respiratory tissues.
One of the distinguishing abilities of Haemophilus influenzae is its capability to communicate with and suppress the immune system, tricking it into believing there is no danger present. The researchers recreated human nasal tissue in the lab to simulate the surfaces of the respiratory tract and observed gene expression changes over a 14-day ‘infection’ period.
The study revealed minimal production of inflammation molecules over time, which would typically be generated shortly after bacteria invade human cells. Professor Kappler explained, “We conducted experiments using both live and dead Haemophilus influenzae, where the dead bacteria triggered a rapid release of inflammatory markers, while live bacteria blocked this response, showcasing the bacterium’s ability to dampen the human immune system.”
Co-author and paediatric respiratory physician, Emeritus Professor Peter Sly from UQ’s Faculty of Medicine, emphasized how these findings shed light on how Haemophilus influenzae can establish chronic infections, residing within the respiratory tract’s surface cells. This unique behavior sets it apart from many other bacteria, allowing it to thrive and cause severe infections when local immunity weakens, such as during a viral infection.
The implications of this research are significant, paving the way for future investigations into new treatments aimed at preventing these infections. By boosting the immune system’s ability to identify and eliminate these bacteria, researchers hope to develop strategies to stop them in their tracks before further damage ensues.
The findings of this study were recently published in PLOS Pathogens, marking a milestone in understanding how Haemophilus influenzae outsmarts the human immune system and opens doors for innovative approaches in combating respiratory infections.
