Nav: Home

Bacteria can 'outsmart' programmed cell death

December 24, 2019

Certain bacteria can override a defence mechanism of the immune system, so called programmed cell death, through inhibition of death effector molecules by their outer membranes components. Shigella bacteria, which cause diarrhoea, use lipopolysaccharides (LPS) on their surface to block the effector caspases. Lipopolysaccharides are a component of the bacterial outer membrane. This strategy enables the bacteria to multiply within the cell. This is the result of a study conducted by the molecular immunologist Professor Hamid Kashkar and his team in the institute for Medical Microbiology and Immunology at the CECAD Cluster of Excellence in Aging Research at the University of Cologne. The article 'Cytosolic Gram-negative bacteria prevent apoptosis by inhibition of effector caspases through LPS' by Günther et al. appeared in the current issue of Nature Microbiology.

Various bacterial pathogens can escape our immune system by staying and multiplying within our body cells (intracellularly). The intracellular propagation of pathogens later leads to cell breakdown and the release of microorganisms that infect neighbouring cells, spread and cause tissue damage and infectious disease. However, the body has a response to this bacterial strategy: programmed cell death, or apoptosis, reacts to cellular stress situations during infections and causes quick suicide of the infected cells.

Due to this rapid self-destruction programme of our body cells, pathogens cannot multiply - the immune system successfully eliminates them. Scientists have observed in the past that pathogens can effectively block apoptosis, allowing them to reproduce and spread intracellularly. However, the molecular mechanism responsible for how these bacteria 'outsmarted' the immune system was largely unknown.

Kashkar lab has now showed that the pathogen that causes shigellosis (Shigella), a typical cause of acute inflammatory diarrhoea, blocks apoptosis by efficiently blocking certain enzymes, so-called caspases, which act as engines that initiate apoptosis.

The biologists showed that lipopolysaccharides bind and block the caspase. Bacteria without complete LPS, on the other hand, spark apoptosis, which blocks them from reproducing intracellularly. They are successfully eliminated by the immune system and thus no longer able to cause infectious diseases. Kashkar lab's work has thus deciphered an important bacterial strategy to prevent the rapid death of the host cell and establish a niche to spread.
-end-


University of Cologne

Related Immune System Articles:

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.
Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.
How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.
Immune system upgrade
Theoretically, our immune system could detect and kill cancer cells.
Using the immune system as a defence against cancer
Research published today in the British Journal of Cancer has found that a naturally occurring molecule and a component of the immune system that can successfully target and kill cancer cells, can also encourage immunity against cancer resurgence.
First impressions go a long way in the immune system
An algorithm that predicts the immune response to a pathogen could lead to early diagnosis for such diseases as tuberculosis
Filming how our immune system kill bacteria
To kill bacteria in the blood, our immune system relies on nanomachines that can open deadly holes in their targets.
Putting the break on our immune system's response
Researchers have discovered how a tiny molecule known as miR-132 acts as a 'handbrake' on our immune system -- helping us fight infection.
Decoding the human immune system
For the first time ever, researchers are comprehensively sequencing the human immune system, which is billions of times larger than the human genome.
Masterswitch discovered in body's immune system
Scientists have discovered a critical part of the body's immune system with potentially major implications for the treatment of some of the most devastating diseases affecting humans.
More Immune System News and Immune System Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Processing The Pandemic
Between the pandemic and America's reckoning with racism and police brutality, many of us are anxious, angry, and depressed. This hour, TED Fellow and writer Laurel Braitman helps us process it all.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Invisible Allies
As scientists have been scrambling to find new and better ways to treat covid-19, they've come across some unexpected allies. Invisible and primordial, these protectors have been with us all along. And they just might help us to better weather this viral storm. To kick things off, we travel through time from a homeless shelter to a military hospital, pondering the pandemic-fighting power of the sun. And then, we dive deep into the periodic table to look at how a simple element might actually be a microbe's biggest foe. This episode was reported by Simon Adler and Molly Webster, and produced by Annie McEwen and Pat Walters. Support Radiolab today at Radiolab.org/donate.