Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Immunological defense mechanism leaves malaria patients vulnerable to deadly infection

19.12.2011
The link between malaria and salmonella infections has been explained for the first time, opening the way to more effective treatments.

Malaria patients are at high risk of developing fatal bacterial infections, especially salmonella infections. This is commonly believed to be due to generalised immunosuppression by malaria, whereby the entire immune system is weakened and compromised.

However, researchers at the London School of Hygiene & Tropical Medicine have discovered that the increased vulnerability to salmonella infections is a side effect of the body's attempts to protect itself from the damaging effects of the malaria infection.

The researchers describe this defence mechanism as a trade-off, where the body fights one enemy but exposes itself to the other. This was demonstrated in their study exploring the connection between malaria and non-typhoid salmonella (NTS)- an infection which is particularly dangerous for children.

Children with malaria can develop anaemia, which puts them at higher risk of developing severe bacterial infections of the blood, caused in up to 70% of the cases by NTS. This infection is fatal in up to 25% of the infected children. To prevent these bacterial infections, or develop an effective treatment, scientists needed to understand the mechanism behind this connection between malaria and salmonella.

Professor Eleanor Riley, one of the lead authors of the study, says: "It is a widespread belief that malaria is an immunosuppressive disease; that once the disease is contracted, the patient will be susceptible to several other infections because of a compromised immune system. However, this study shows that increased susceptibility to salmonella infections is due to a very specific immunological effect which does not affect the immune system as a whole."

Infection by the malaria parasite periodically causes red blood-cells to burst, releasing the parasite offspring, but also releasing heme – a breakdown product of haemoglobin – which is extremely toxic once outside the red blood cell.

The Medical Research Council (MRC) funded study, published in Nature Medicine, found that in malaria-infected mice (which show exactly the same susceptibility to salmonella as is seen in humans) the body's natural response to defend itself from the dangers of heme, an enzyme that degrades it (heme oxygenase-1 or HO-1), very selectively affects the immune system, crippling the production of white blood-cells (neutrophils) that are essential to fight NTS. These crippled cells are unable to kill the bacteria, allowing them to spread freely.

"The key is in the rupture of the red-blood cells," says Dr Aubrey Cunnington, Clinical Research Fellow at LSHTM and co-author of the study. "Sickle-cell anaemia patients, where similar red cell damage occurs, are also more susceptible to NTS. But, numerically speaking, malaria is the most common cause of NTS. Where the incidence of malaria is decreasing, so are the salmonella infections."

The team identified Tin Protoporphyrin (SnPP) as a candidate for the prevention of salmonella infection. SnPP inhibits the activity of the heme oxygenase enzyme, reversing the susceptibility to salmonellosis in malaria infections.

But the authors say that careful testing will be needed before considering SnPP use in humans, as blocking the action of HO-1 may leave the heme free to cause tissue damage.

For further information or to request interviews please contact the press office of the London School of Hygiene & Tropical Medicine by emailing Paula.Fentiman@lshtm.ac.uk or Giorgio.Defaveri@lshtm.ac.uk or calling +44 (0)20 7927 2802.

Notes for Editors

1. Reference Article. A.J. Cunnington, J.B. de Souza, R-M. Walther, E.M.Riley; Malaria impairs resistance to Salmonella through heme- and heme oxygenase–dependent dysfunctional granulocyte mobilization, Nature Medicine, (2011), http://dx.doi.org/10.1038/nm.2601

2. Additional research notes. Although this study was carried out in mice, the team's ongoing (unpublished) studies in The Gambia have confirmed that exactly the same type of neutrophil dysfunction occurs in children with malaria. Importantly, their neutrophil function is impaired for up to two months after treatment of their malaria infection, leaving them at risk of NTS infection for many weeks after recovering from their acute episode of malaria.

3. About LSHTM. The London School of Hygiene & Tropical Medicine (LSHTM) is a renowned research-led postgraduate institution of public health and global health. Its mission is to improve health in the UK and worldwide through the pursuit of excellence in research, postgraduate teaching and advanced training in national and international public health and tropical medicine, and through informing policy and practice in these areas. Part of the University of London, the School is the largest institution of its kind in Europe with a remarkable depth and breadth of expertise encompassing many disciplines associated with public health. www.lshtm.ac.uk

4 - About the MRC. For almost 100 years the Medical Research Council has improved the health of people in the UK and around the world by supporting the highest quality science. The MRC invests in world-class scientists. It has produced 29 Nobel Prize winners and sustains a flourishing environment for internationally recognised research. The MRC focuses on making an impact and provides the financial muscle and scientific expertise behind medical breakthroughs, including one of the first antibiotics penicillin, the structure of DNA and the lethal link between smoking and cancer. Today MRC funded scientists tackle research into the major health challenges of the 21st century.

Paula Fentiman | EurekAlert!
Further information:
http://www.lshtm.ac.uk
http://www.mrc.ac.uk

More articles from Health and Medicine:

nachricht Nanoparticles as a Solution against Antibiotic Resistance?
15.12.2017 | Friedrich-Schiller-Universität Jena

nachricht Plasmonic biosensors enable development of new easy-to-use health tests
14.12.2017 | Aalto University

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: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

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...

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

New technique could make captured carbon more valuable

15.12.2017 | Life Sciences

First-of-its-kind chemical oscillator offers new level of molecular control

15.12.2017 | Life Sciences

A chip for environmental and health monitoring

15.12.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>