How tiny bacteria outsmart the human immune system

Respiratory infections are as ubiquitous as they are overwhelming. However, what if a bacterium known widely as Haemophilus influenzae, has a unique trick up its microscopic sleeve? It “turns off” our immune systems to thrive and sustain. 

This fascinating revelation comes to from the heart of the labs at The University of Queensland. The study was led by Professor Ulrike Kappler from UQ’s School of Chemical and Molecular Biosciences. 

Bacteria vs. immune system

Let’s take a detour into the fascinating world of bacteria. They’re not always the bad guys as we often perceive them to be.

However, bacteria like Haemophilus influenzae are clever survivors. They dodge blows from our immune system as they’ve perfected their camouflage art. Sadly, our immunity fails to spot them.

Our immune system is the unsung hero within us. It fights tirelessly to detect and eliminate harmful germs. Yet, bacteria can outfox these defenses. They use the immune system to their advantage.

Vulnerable groups

The tiny organisms can wreak havoc in vulnerable individuals. They put these individuals at the mercy of worsening symptoms.

“These bacteria are especially damaging to vulnerable groups, such as those with cystic fibrosis, asthma, the elderly, and Indigenous communities,” noted Professor Kappler.

“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.”

Keen to know how this bacterium operates? The answer, quite surprisingly, lies in its ability to “talk” to and deactivate our immune system. It performs an impressive act of deception, convincing our defense mechanisms that there’s no threat looming.

Simulation of infection

The nefarious operations of this bacterium unravel its ability to “talk” to and deactivate our immune system. It’s an impostor in our midst, convincing our body that there’s no threat on the horizon.

To understand this phenomenon, the UQ team simulated an infection by preparing human nasal tissue in the lab. This artificial environment mimicked the lining of our respiratory tracts. Over two weeks of ‘infection,’ they monitored the changes in gene expression.

Their findings? An astoundingly limited production of inflammation molecules, the body’s usual response to bacterial invasion.

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

Bacteria and immune systems

Collaborating on this research journey is pediatric respiratory physician Emeritus Professor Peter Sly from UQ’s Faculty of Medicine. 

“This is a rare behavior that many other bacteria don’t possess,” noted Professor Sly. “If local immunity drops, for example during a viral infection, the bacteria may be able to ‘take over’ and cause a more severe infection.”

The valuable insights derived from this study will pave the path towards finding new treatments.

“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,” said Professor Kappler.

Bacteria and immune system dynamics

As the intricate dynamics between bacteria and our immune system continue to unfold, we remain curious, fascinated, and a tad bit wary. 

Additionally, exploring how this bacterium interacts with other pathogens and the microbiome might reveal complex interdependencies that either hinder or assist its survival.

After all, isn’t it a strange thought to consider how the microscopic organisms in our bodies pull the strings? Does this knowledge make you look at common respiratory infections in a new light?

Public health and beyond

This newfound understanding of Haemophilus influenzae’s sneaky abilities underscores the importance of early detection and targeted treatment.

This research can directly benefit public health initiatives by fostering the development of more effective diagnostic tools and preventative measures.

Moreover, the possibility of refining vaccines and developing therapies to counteract the bacterium’s evasive strategies could potentially mitigate the impact of associated respiratory infections.

The study is published in the journal PLOS Pathogens.

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