Carbon monoxide could help malaria10th May 2011
Scientists in Portugal have succeeded in laying bare the exact genetic mechanism through which people with sickle-cell anaemia are protected against malaria.
The findings could pave the way for the development of new malaria treatments.
Sickle-cell anaemia exists in people who inherit at least two faulty genes.
In those people, red blood cells are abnormally shaped, giving the condition its name.
The genes governing the disease code for haemoglobin, a protein which carries oxygen around the body in red blood cells.
However, the gene has persisted through countless generations because of a side-effect: it gives the carrier some resistance to the deadly tropical killer disease, malaria.
A research team led by Miguel Soares and Ana Ferreira of the Gulbenkian Institute of Science in Oeiras, Portugal found that the gene does this not by protecting against infection by the malaria parasite, as was widely believed.
In studies on genetically modified mice, they found that the faulty gene prevented the disease from taking hold after infection.
One component of the haemoglobin molecule, known as haem, is present in free form in mice with the faulty gene.
Normal mice did not have it at all, however.
So the team injected a group of normal mice with haem, and then infected them with malaria.
This haem-injected group did not go on to develop malaria.
However, Soares and his team also discovered that too much haem could have the opposite effect, and promote the malaria parasite.
The researchers, writing in the journal Cell, speculated that free haem might act in a manner similar to a vaccination, meaning that it can be dangerous and protective, depending on the concentration.
Free haem in the bloodstream was also found to be self-limiting in mice with one sickle-cell gene, because of the role played by carbon monoxide.
They tested their hypothesis by allowing a group of malaria-infected mice to inhale small quantities of carbon monoxide, not enough to be toxic.
This group of mice did not develop the disease, either.
The study concluded that small quantities of carbon monoxide could be beneficial in people already infected with the malaria parasite.
However, they said that more factors were at play in malaria than just the level of free haem in the blood.
An inflammatory response to the disease is also known to play a role, boosting levels of toxic T-cells in the blood.
However, mice carrying one sickle-cell gene were protected against such a build-up, although they have not yet discovered exactly why.
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Title: Carbon monoxide could help malaria
Author: Luisetta Mudie
Article Id: 18398
Date Added: 10th May 2011