Navigation Links
Immunological defense mechanism leaves malaria patients vulnerable to deadly infection
Date:12/18/2011

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.


'/>"/>

Contact: Paula Fentiman
paula.fentiman@lshtm.ac.uk
44-207-927-2802
London School of Hygiene & Tropical Medicine
Source:Eurekalert

Related biology news :

1. Pitt/UPMC: Exceptional cognitive and physical health in old age leaves immunological fingerprint
2. Keystone Symposia to hold conference in Seattle on immunological mechanisms of vaccination
3. How Salmonella forms evil twins to evade the bodys defenses
4. An unexpected player in a cancer defense system
5. Targeting bacterial gas defenses allow for increased efficacy of numerous antibiotics
6. GTSI Wins Department of Defense Contract to Provide Biometric Automated Toolset Systems for U.S. Army
7. Encyclopedia of Bioterrorism Defense, 2nd edition
8. Rainbows without pigments offer new defense against fraud
9. MU researchers find missing link in plant defense against fungal disease
10. Big picture of how interferon-induced genes launch antiviral defenses revealed
11. Host or foreign -- the bodys frontline defense mechanism understood
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/24/2016)... Ampronix facilitates superior patient care by providing unparalleled technology to leaders of ... the latest premium product recently added to the range of products distributed by Ampronix. ... ... ... Medical Display- Ampronix News ...
(Date:5/3/2016)... VILNIUS, Lithuania , May 3, 2016 /PRNewswire/ ... today released the MegaMatcher Automated Biometric Identification ... deployment of large-scale multi-biometric projects. MegaMatcher ABIS can ... and accuracy using any combination of fingerprint, face ... of MegaMatcher SDK and MegaMatcher ...
(Date:4/19/2016)... The new GEZE SecuLogic access ... "all-in-one" system solution for all door components. It can ... door interface with integration authorization management system, and thus ... minimal dimensions of the access control and the optimum ... offer considerable freedom of design with regard to the ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... 2016 , ... Supplyframe, the Industry Network for electronics hardware ... . Located in Pasadena, Calif., the Design Lab’s mission is to bring together ... built and brought to market. , The Design Lab is Supplyframe’s physical representation ...
(Date:6/23/2016)... 2016  Blueprint Bio, a company dedicated to identifying, ... community, has closed its Series A funding round, according ... "We have received a commitment from Forentis Fund ... to meet our current goals," stated Matthew Nunez ... to complete validation on the current projects in our ...
(Date:6/23/2016)... ... June 23, 2016 , ... Regulatory Compliance Associates® Inc. (RCA), ... free webinar on Performing Quality Investigations: Getting to Root Cause. ... no charge. , Incomplete investigations are still a major concern to the Regulatory ...
(Date:6/22/2016)... , June 22, 2016 Cell ... will allow them to produce up to one ... one lot within one week. These high-quality, consistent ... laboriously preparing cells and spend more time doing ... through a proprietary, high-volume manufacturing process that produces ...
Breaking Biology Technology: