Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacteria persist as stowaways

08.02.2018

HZI scientists decipher the mechanism used by gastrointestinal germs to switch their infection programme from acute to chronic

Each year, bacteria of the Yersinia genus cause several thousand cases of gastrointestinal infections in Germany alone. In most cases, the human immune system manages to eliminate the bacteria. But in a fraction of the afflicted individuals, a chronic infection develops that can promote the manifestation of autoimmune diseases in the long term.


Bacteria of the species Yersinia pseudotuberculosis invade human tissue.

HZI/Manfred Rohde

Scientists from the Helmholtz Centre for Infection Research (HZI) in Braunschweig recently discovered the trick these Yersinia germs use to hide from the immune system: They reduce the production of a toxin by means of which they promote the inflammation of the afflicted tissue during an acute infection. As a result, the inflammation subsides allowing the bacteria to escape the attention of the immune system. The researchers published their results in PLOS Pathogens.

The most widely known Yersinia germ is Yersinia pestis, the cause of the plague that can be transmitted by fleabites. Other species, such as Yersinia enterocolitica and Yersinia pseudotuberculosis, usually enter the human body via contaminated foods, for example raw pork meat, and can elicit severe diarrhoeal diseases or vomiting.

This is how the body eliminates the majority of the pathogens, while the immune system takes over the remaining clean-up work. However, a Yersinia infection can just as well become chronic and then even promote autoimmune diseases, such as reactive arthritis. But it is still unclear how the bacteria manage to survive for years inside the body without being detected by the immune system and how they promote immune reactions against a body's own tissue.

Some Yersinia strains produce a toxin called CNFY during the acute infection phase and release it into the host cells. Once inside the cells, the substance blocks cell division which, in turn, leads to a steadily increasing cell size and facilitates the attack by the pathogen. "Yersinia uses CNFY to accelerate the spread of the infection and inflammation in the tissue, which is ultimately fatal for the infected host," says Prof Petra Dersch, who is the director of the "Molecular Infection Biology" department at the HZI.

Mice usually overcome a Yersinia infection rapidly and without being harmed. Approximately ten percent of the cases are fatal and approximately ten percent turn chronic. Petra Dersch and her team of researchers at the HZI applied state-of-the-art sequencing methods to look very closely at the mice showing a chronic course of disease and the associated Yersinia germs:

A transcriptome analysis revealed which genes in the bacteria and the mice are active and which are not. "We found the production of CNFY in the persisting, i.e. surviving, yersiniae to be down-regulated," says Dersch. "But in the absence of CNFY, the immune system no longer detects the bacteria, the inflammatory reaction subsides and the mice survive. This trick allows the yersiniae to hide for months in the caecum (appendix) of the mice."

Tissue analyses done by microscope also reveal a difference between yersiniae causing acute versus chronic infection: During acute infection phases, the rapidly growing bacteria produce micro-colonies that are recognised by the immune system. In contrast, the persistent bacteria are found as single cells within the tissue, which makes them more difficult to detect.

Collaborating with Dr Till Strowig, the head of the "Microbial Immune Regulation" Young Investigator group at the HZI, the scientists also showed that Yersinia pathogens can even change the microbial community in the intestines. "A Yersinia infection shifts the composition of the microbiota in the intestines in favour of inflammation-promoting bacterial species," says Dersch.

It has been known for a long time that there is a correlation between Yersinia infections and inflammatory autoimmune diseases, such as a reactive arthritis, but the underlying mechanism is still unknown. "Our transcriptome analyses showed that the immune response to the residing bacteria in the chronically infected mice is rather inconspicuous, but still detectable," says Petra Dersch. "Consequently, antibodies against inherent tissue might be produced since some of the surface structures of the host cells resemble those of the bacteria. This might also explain the increased manifestation of arthritis in Yersinia patients."

In January, Petra Dersch was admitted to the European Academy of Microbiology. Founded in 2009, the Academy promotes microbiological research in Europe and aims to cross-link the scientists more closely. To this end, the Academy organises meetings and congresses and develops recommendations concerning critical issues of microbiology. The members of the Academy are renowned scientists who are elected by the Academy.

Original publication:
Wiebke Heine, Michael Beckstette, Ann Kathrin Heroven, Sophie Thiemann, Ulrike Heise, Aaron M. Nuss, Fabio Pisano, Till Strowig, Petra Dersch: Loss of CNFy toxin-1 induced inflammation drives Yersinia pseudotuberculosis into persistency. PLOS Pathogens, 2018, DOI: 10.1371/journal.ppat.1006858

The press release and a picture are also available on our website: https://www.helmholtz-hzi.de/en/news_events/news/view/article/complete/bacteria_...

Helmholtz Centre for Infection Research:
Scientists at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, Germany, are engaged in the study of different mechanisms of infection and of the body’s response to infection. Helping to improve the scientific community’s understanding of a given bacterium’s or virus’ pathogenicity is key to developing effective new treatments and vaccines. The HZI is a partner of the German Center for Infection Research (DZIF). http://www.helmholtz-hzi.de/en

Contact:
Susanne Thiele, Press Officer
susanne.thiele@helmholtz-hzi.de
Dr Andreas Fischer, Editor
andreas.fischer@helmholtz-hzi.de

Helmholtz Centre for Infection Research
Press and Communication
Inhoffenstr. 7
D-38124 Braunschweig
Germany

Phone: +49 531 6181-1404

Susanne Thiele | Helmholtz-Zentrum für Infektionsforschung

More articles from Life Sciences:

nachricht New image of a cancer-related enzyme in action helps explain gene regulation
05.06.2020 | Penn State

nachricht Protecting the Neuronal Architecture
05.06.2020 | Universität Heidelberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Restoring vision by gene therapy

Latest scientific findings give hope for people with incurable retinal degeneration

Humans rely dominantly on their eyesight. Losing vision means not being able to read, recognize faces or find objects. Macular degeneration is one of the major...

Im Focus: Small Protein, Big Impact

In meningococci, the RNA-binding protein ProQ plays a major role. Together with RNA molecules, it regulates processes that are important for pathogenic properties of the bacteria.

Meningococci are bacteria that can cause life-threatening meningitis and sepsis. These pathogens use a small protein with a large impact: The RNA-binding...

Im Focus: K-State study reveals asymmetry in spin directions of galaxies

Research also suggests the early universe could have been spinning

An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...

Im Focus: New measurement exacerbates old problem

Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.

Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

New image of a cancer-related enzyme in action helps explain gene regulation

05.06.2020 | Life Sciences

Silicon 'neurons' may add a new dimension to computer processors

05.06.2020 | Physics and Astronomy

Protecting the Neuronal Architecture

05.06.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>