Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Helicobacter pylori - the key behind its recognition is somewhere else

01.11.2004


The first step against infection is the detection of microorganisms capable of causing disease. This is done through the recognition of molecular structures not shared by the host, but also present in other harmless or even useful microbes. A question that has puzzled scientists for many years is how the host knows exactly against which microbes to mount an immune response. But now, in the November issue of Nature Immunology, scientists describe for the first time an ingenious bacteria-recognition mechanism by epithelial cells, which allows the distinction to be made between dangerous and innocuous bacteria.

The innate immune system is the mammals’ first line of defence as it can be mobilised almost immediately, and so has a crucial role in the prevention and/or fight of infection. Key players in the recognition of bacteria are two families of receptors: Toll-like receptors (TLR), which are normally expressed in cell membranes, and the nucleotide-binding oligomerization domain (Nod) family, found in the cytoplasm.

A simple system by which the innate immune system can differentiate between pathogenic (disease-inducing) and non-pathogenic bacteria is by selective expression of these receptors. For example, TLR and Nod receptors, specific for bacterial molecular components, are expressed in sterile areas of the body like the internal organs, the bloodstream or the cytoplasm. The logic behind this is that if bacteria are found at those locations it would be as result of an infection and consequently an immune response should be mounted. This differential receptor expression however, can not explain how in places like the digestive system, where a varied population of both pathogenic and non-pathogenic extracellular bacteria exist, we are still able to discriminate and attack only the those which can induce disease.



But now Jérôme Viala , Catherine Chaput, Ivo G. Boneca, Richard L. Ferrero and colleagues at the Institute Pasteur in Paris, the National University of Ireland and the Millenium Pharmaceuticals in Cambridge, Massachusetts, USA while working on the mechanism of recognition by epithelial cells of a pathogenic variant of Helicobacter pylori (H. pylori) which is associated with ulcers and stomach cancer, found one such mechanism of discrimination between “good” and “bad” bacteria.

The team of scientist discovered that the inflammatory reaction of epithelial cells in response to H. pylori was triggered through Nod1, a member of the Nod receptor family, localised in the cytoplasm of the epithelial cells. This was very interesting, as H. pylori does not enter the cells during infection and until now was thought to be recognised through a member of the TLR family, which are normally localised on the cell surface.

In addition, Viala , Ferrero and colleagues also show that the activation of Nod1 and subsequent inflammatory response against infection, was dependent of a bacterial syringe-like structure called type IV secretion system.

Further experiments led to the discovery that H. pylori induces an inflammatory response in gastric epithelial cells by injecting peptidoglycan, a component of the bacterial cell wall, into these cells through a type IV secretion system. The peptidoglycan is then recognised in the cytoplasm by Nod1 leading to the production of pro-inflammatory molecules, which will start an immune response against the pathogenic bacteria. It is not clear why bacteria have conserved such a mechanism if, as it seems, it can be harmful for their survival but one hypothesis is that it might have advantages not yet discovered.

These results are extremely interesting when considering the fact that while most pathogenic bacteria present this type of syringe-like secretion systems, non-pathogenic bacteria, on the other hand, generally do not have such systems of interaction. A good example is non-pathogenic variants of H. pylori which have no secretion system.

Viala , Ferrero and colleagues’s work is very important for the understanding of how the body deals with infection not only because it shows that an intracellular receptor (Nod1) can recognise an extracellular bacterium without this entering the cytoplasm, but also because it describes for the first time a bacterial recognition system that is able to discriminate between dangerous and innocuous microorganisms and mount a response only when necessary.

Piece researched and written by: Catarina Amorim (catarina.amorim@linacre.ox.ac.uk)

Catarina Amorim | alfa
Further information:
http://www.nature.com
http://www.oces.mcies.pt

More articles from Health and Medicine:

nachricht Hot cars can hit deadly temperatures in as little as one hour
24.05.2018 | Arizona State University

nachricht 3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

Beyond the limits of conventional electronics: stable organic molecular nanowires

24.05.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>