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 from UQ's 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.
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." Professor Ulrike Kappler from UQ's School of Chemical and Molecular Biosciences Professor Kappler said 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.