Respiratory bacteria turn off immune system to survive, study finds

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," Professor Kappler said. "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."

"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," Professor Kappler said. "This proved that the bacteria can actively reduce the human immune response."

Image source: University of Queensland.