Shetland pony study offers clues that could help prevent allergies in people

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A Culicoides biting midge.
A Culicoides biting midge.

Long-tormented allergy sufferers might one day have Shetland ponies to thank for their blessed relief.

The immune response of Shetland ponies to insect bites has been studied by an international team of scientists, whose findings could ultimately prevent people developing allergies.

The researchers have shown that the horse immune system can respond to midge bites in a way that prevents – rather than triggers – allergic reactions.

The ponies’ immune response to bites is similar to what happens in people with allergies.

Understanding what triggers allergic reactions could help researchers come up with ways to stop people developing sensitivities.

It was previously thought that ponies which do not suffer reactions to bites do so because their immune system does not recognise the allergens carried by the insects.

However, the researchers found that all horses responded, with their immune systems generating two kinds of responses.

One response produces allergy symptoms, such as itching and inflammation, while the other prevents an allergic reaction.

After being exposed to midges, the horse immune system can release cytokines, which affect the behaviour of other cells.

Ponies that react to midge bites release cytokines known as IL-4, which trigger allergy symptoms.

In ponies that are not sensitive to bites, another cytokine, INF-?, is released, which blocks cells that would otherwise trigger allergic reactions.

It could be possible to prevent people developing sensitivities through priming the human immune system to respond in a way that does not trigger reactions.

Allergies are caused by complex interactions between genetic and environmental factors.

The reason why some individuals develop sensitivities, while others do not, is not fully understood.

The study, published in the open-access journal PLOS ONE, was funded by the Dutch Foundation for Technical Sciences and was carried out by researchers in Britain, South Africa and the Netherlands, with most of the Dutch scientists based at Utrecht University.

“We believe this finding could have direct practical implications, for example by helping immune responses to choose the ‘right’ direction in individuals who we would like to protect from developing occupation-associated allergies,” said one of the study’s authors, Dr Dietmar Zaiss, from the School of Biological Sciences at Scotland’s University of Edinburgh.

The study is entitled, “Allergen-Specific Cytokine Polarization Protects Shetland Ponies against Culicoides obsoletus-induced Insect Bite Hypersensitivity”.

Meulenbroeks C, van der Lugt JJ, van der Meide NMA, Willemse T, Rutten VPMG, et al. (2015) Allergen-Specific Cytokine Polarization Protects Shetland Ponies against Culicoides obsoletus-Induced Insect Bite Hypersensitivity. PLoS ONE 10(4): e0122090. doi:10.1371/journal.pone.0122090

The full study can be read here

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