Nav: Home

Time to put TB on a diet!

January 19, 2017

Global Tuberculosis Report, the disease kills over 1.5 million people a year. Although the mortality rate has dropped by 47% since 1990 due to advances in preventive and treatment options, the tuberculosis bacillus is growing increasingly resistant to antibiotics. For this reason, biochemists at the University of Geneva (UNIGE), Switzerland, are attempting to identify the mechanisms that enable the bacterium to reproduce, spread and survive in latent form in our macrophages. The scientists have discovered that the bacterium has the ability to "reprogramm" the cell it infects so that it can feed on its lipids. The UNIGE research results, which will be published in the PLOS Pathogens journal, will pave the way for new treatment opportunities based on starving and weakening the bacterium.

Tuberculosis is a highly contagious disease that spreads through the air via droplets of saliva. Although treatments exist for tuberculosis, new antibiotic-resistant strains are preventing TB from being eradicated. The goal is to find new ways to tackle the disease, which requires a thorough understanding of how the bacterium, known as Mycobacterium tuberculosis, behaves once it takes hold of the macrophages in our lungs. The team headed by Thierry Soldati, Professor at the Biochemistry department in UNIGE's Science faculty, has been working on a model system that acts like the macrophages in our immune system: the social amoeba Dictyostelium, a unicellular microorganism.

«We infected the amoebae with the Mycobacterium marinum bacterium, which induces tuberculosis in fish,» explains Caroline Barisch, a researcher at UNIGE and the study's first author. «The pathogen behaves in the same manner as the TB bacillus, which means that we were able to use our simple and ethically responsible system to undertake experiments that could not be carried out directly on humans.» Scientists had previously recognised that for the bacterium to survive, replicate and spread, it needed to consume the lipids that exist in the form of droplets in macrophages. Without this source of food, the bacillus cannot survive latently and wait for a weakness in the immune system in order to develop. It is well worth remembering that 30% of the world's population is infected by a dormant form of the TB bacillus.

The UNIGE biochemists observed the infection in vitro, analysing each stage of the process whereby the bacterium feeds on the lipids of its host. As Thierry Soldati explains: «We subsequently discovered that the mycobacterium can "reprogramm" the infected cell so that it diverts and attracts all the amoeba's fat reserves --not just the lipid droplets but also the membranes-- so that it can feed on them.» The researchers suppressed the lipid droplets of the host cells, the bacterium's preferred food source, and found that the bacterium has a back-up plan that allows it to compensate for this shortage by drawing on the lipids within the host's membranes. This shows that this lipid diet is most likely crucial for the survival of the bacterium.

«We now know that the bacillus is extremely 'addicted' to this high-fat food,» continues Caroline Barisch. «Our current aim is to find a way to starve the bacillus by depriving it of access to the fat stores in our macrophages. The goal will be to target the enzymes of the bacillus and render them incapable of absorbing lipids.» It is a discovery that opens the door to the prospect of new forms of treatment for neutralising the strains that are resistant to antibiotics.
-end-


Université de Genève

Related Immune System Articles:

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.
How a fungus can cripple the immune system
An international research team led by Professor Oliver Werz of Friedrich Schiller University, Jena, has now discovered how the fungus knocks out the immune defenses, enabling a potentially fatal fungal infection to develop.
How the immune system protects us against bowel cancer
Researchers from Charité - Universitätsmedizin Berlin have discovered a protective mechanism which is used by the body to protect intestinal stem cells from turning cancerous.
How herpesviruses shape the immune system
DZIF scientists at the Helmholtz Zentrum München have developed an analytic method that can very precisely detect viral infections using immune responses.
More Immune System News and Immune System Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab