Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Immune factor allows viral infections to become chronic

08.03.2016

Many viral diseases tend to become chronic – including infections with the HI virus. In persons affected, the immune response is not sufficient to eliminate the virus permanently. Scientists at the University of Bonn have now identified an immune factor which is partially responsible for this. Their results give rise to hopes for new therapeutic approaches. The work, which included researchers from the University of Cologne and the Technical University of Munich, is being published in the renowned journal "Nature Immunology."

The HI virus triggers the immunodeficiency disease AIDS. The infection has a chronic course – the immune system is not able to get rid of the pathogen. This is due among other things to the fact that the virus directly attacks and destroys certain immune cells known as helper T cells.


Prof. Dr. Joachim L. Schultze and Dr. Marc Beyer (from left) from LIMES Institute of University of Bonn.

(c) Photo: Barbara Frommann/Uni Bonn


In the lab: Dr. Zeinab Abdullah from the Institute of Experimental Immunology at University Hospital Bonn.

(c) Photo: Uniklinik RWTH Aachen

However, many helper T cells are not affected by the virus at all. Nonetheless their function is impaired in the case of AIDS. Normally, helper T cells secrete inflammatory messengers during an infection. As a result of this chemical distress call, killer T cells (the body's own defense troops) become ready to fight and are guided to the site. By contrast, in AIDS and other chronic infections, the helper T cells remain silent. But why is that?

To answer this question, the researchers initially analyzed which genes in the silent helper cells of HIV patients are active. Result: In chronic inflammation, the immune function of the helper T cells is inhibited by various signaling pathways. These signaling pathways in turn are apparently controlled by a single molecule known as tumor necrosis factor (TNF).

This factor appears to be responsible for the weak immune response. "We investigated mice suffering from a chronic viral infection similar to an HIV infection and inactivated the TNF molecule in them," explains Dr. Marc Beyer from Life and Medical Sciences Institute (LIMES) of the University of Bonn. "As a result, the helper T cells worked normally once again. After ten days, the animals had completely eliminated the virus; they were healthy."

Misdirected protective function

Paradoxically, the tumor necrosis factor has exactly the opposite effect in acute viral attacks: It brings the immune system up to full speed and additionally ensures that cells infected with the virus commit suicide. "Therefore, in an acute infection, large quantities of TNF are formed very rapidly," says Dr. Zeinab Abdullah from the Institute of Experimental Immunology at the University Hospital Bonn. "In chronic infections, on the other hand, the body secretes small amounts of TNF over a long period of time. This appears to cause the helper T cells to shut down to some extent."

The researchers suspect that this is a protective mechanism. A prolonged strong immune reaction can in particular destroy healthy tissues as well – with life-threatening consequences. TNF could act as a type of emergency brake which prevents this. Exactly what the tumor necrosis factor does on a molecular level is still largely unknown. The scientists involved now want to examine this question in detail.

The results may establish new therapeutic options in the medium term. Thus there are drugs which inhibit the effect of TNF. These TNF blockers are used in the treatment of autoimmune diseases such as rheumatism, for example. They are to prevent defense cells from attacking the body itself. "Among other things, we want to investigate what effects these drugs have in rheumatism patients who are additionally suffering from a chronic viral infection," says Marc Beyer.

Publication: Tumor-necrosis factor impairs CD4+ T cell-mediated immunological control in chronic viral infection; Nature Immunology; DOI: 10.1038/ni.3399

Media contact information:

Dr. Marc Beyer
LIMES Institute
University of Bonn
Tel. ++49-228-7362792
Email: marc.beyer@uni-bonn.de

Dr. Zeinab Abdullah
Institute of Experimental Immunology
University Hospital Bonn
Tel. ++49-228-28711038
Email: Zeinab.Abdullah@ukb.uni-bonn.de

Johannes Seiler | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bonn.de

More articles from Health and Medicine:

nachricht Research reveals how diabetes in pregnancy affects baby's heart
13.12.2017 | University of California - Los Angeles Health Sciences

nachricht Routing gene therapy directly into the brain
07.12.2017 | Boston Children's Hospital

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Gecko adhesion technology moves closer to industrial uses

13.12.2017 | Information Technology

Columbia engineers create artificial graphene in a nanofabricated semiconductor structure

13.12.2017 | Physics and Astronomy

Research reveals how diabetes in pregnancy affects baby's heart

13.12.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>