Discovery of a new trigger for antifungal defence
Scientists at the MRC Centre for Medical Mycology made a discovery that could help in the fight against a fungus that kills around 200,000 people every year and causes lung and allergic diseases in millions of others.
Aspergillosis is one of the most feared complications for patients undergoing treatments such as organ transplantation as it can lead to an invasive infection that is fatal in over 50% of cases. It is also thought to be responsible for a range of different lung diseases including asthma, in millions of people worldwide.
Aspergillosis infection is caused by a fungus called Aspergillus fumigatus, a common mould which is found in soil and compost heaps and is transported in the air as microscopic spores.
The spores from Aspergillus are inhaled by everybody every day, and for most healthy people the spores do not lead to disease, but for those with a weakened immune system, such as those undergoing chemotherapy for cancer or transplant surgery, or those with a lung condition like cystic fibrosis these fungal infections can be deadly.
The fungus is so effective because it is very difficult to diagnose and treat. Scientists have been trying to understand how the human immune system recognises the fungus so they can develop therapies based on stimulating these body’s defences.
A study led by researchers at the MRC Centre for Medical Mycology identified a novel mechanism which responds to an ‘unexpected’ part of the fungus, triggering the immune system.
The team discovered that a key immune mechanism – a receptor on cells called MelLec – recognises a specific pigment in the fungi called melanin. When MelLec senses melanin, it helps send antifungal immune defences into action. This is unusual because it was previously thought that the immune system primarily recognised sugars in the cell wall of fungi.
This group have also found that variants of this receptor in people can make them more susceptible to infection, if they are undergoing medical procedures such as transplantation.
This finding will eventually inform the development of novel diagnostics and drugs to help combat these infections, and to better understand which patient groups may be at a higher risk of developing Aspergillus infections.
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MRC Centre for Medical Mycology