Researchers discover how Haemophilus influenzae bacteria manipulate human immune responses, leading to chronic infections and worsened symptoms.
RT’s Three Key Takeaways:
- Immune System Manipulation: Haemophilus influenzae can deactivate the human immune system, allowing it to persist in the respiratory tract and cause chronic infections.
- Impact on Vulnerable Groups: The bacterium is particularly harmful to individuals with conditions like cystic fibrosis, asthma, COPD, the elderly, and Indigenous communities, significantly worsening their symptoms.
- Future Treatments: The discovery of the bacterium’s ability to suppress immune responses may lead to the development of new treatments that enhance the immune system’s ability to detect and eliminate Haemophilus influenzae.
Researchers from The University of Queensland have identified how a common bacterium is able to manipulate the human immune system during respiratory infections and cause persistent illness.
The research, led by professor Ulrike Kappler, PhD, from the School of Chemical and Molecular Biosciences, studied the virulence mechanisms of Haemophilus influenzae, a bacterium that plays a significant role in worsening respiratory tract infections.
“These bacteria are especially damaging to vulnerable groups, such as those with cystic fibrosis, asthma, the elderly, and Indigenous communities,” says Kappler in a release. “In some conditions, such as asthma and chronic obstructive pulmonary disease, they can drastically worsen symptoms. Our research shows the bacterium persists by essentially turning off the body’s immune responses, inducing a state of tolerance in human respiratory tissues.”
Bacteria Deactivates Immune System
Kappler says the bacterium had a unique ability to “talk” to and deactivate the immune system, convincing it there was no threat.
The researchers prepared human nasal tissue in the lab, growing it to resemble the surfaces of the human respiratory tract, then monitored gene expression changes over a 14-day “infection.”
They found very limited production of inflammation molecules over time, which normally would be produced within hours of bacteria infecting human cells.
“We then applied both live and dead Haemophilus influenzae, showing the dead bacteria caused a fast production of the inflammation makers, while live bacteria prevented this,” Kappler says in a release. “This proved that the bacteria can actively reduce the human immune response.”
Chronic Infections and Future Treatments
Co-author and pediatric respiratory physician emeritus professor Peter Sly, PhD, from the Faculty of Medicine, said the results show how Haemophilus influenzae can cause chronic infections, essentially living in the cells that form the surface of the respiratory tract.
“This is a rare behavior that many other bacteria don’t possess,” Sly says in a release. “If local immunity drops, for example during a viral infection, the bacteria may be able to ‘take over’ and cause a more severe infection.”
Researchers say the findings will lead to future work toward new treatments to prevent these infections by helping the immune system to recognize and kill these bacteria.
“We’ll look at ways of developing treatments that enhance the immune system’s ability to detect and eliminate the pathogen before it can cause further damage,” Kappler says in a release.
The research was published in PLOS Pathogens.
Photo caption: A microscopic view of Haemophilus influenzae bacteria
Photo credit: University of Queensland
