Genetics / Health / Medicine / Science

Epigenetics and allergies

Everybody lately seems to be talking about gut health and its relationship to the growing issue of allergies (be it hayfever or something more serious). But it turns out that’s not the only factor that people are very actively looking into right now: researchers are also starting to point the finger at epigenetics.

I’ve posted about epigenetics before, but here’s a brief recap: epigenetics refers to changes to the DNA we carry in all our cells which aren’t to do with the sequence of bases and helical structure first described by Watson and Crick (based on the crystallography work of Rosalind Franklin, without whom they would have taken a lot longer to find the answers). These modifications can be in the form of tags called methyl and acetyl groups, which attach to the bases, or they can be changes to the proteins called histones which DNA wraps around. Both of these types of epigenetic change are thought to contribute to allergic reactions.

How does that work? Well, these epigenetic modifications can make it easier or harder to “read” particular stretches of DNA. If DNA is harder to read, chances are that less of it will be transcribed, which means ultimately, less of it will be translated into new proteins. Histones in particular have been found to influence the regulation of cells intimately involved with allergic reactions, like T-cells, macrophages and fibroblasts.

Allergic reactions happen when the body recognises some shape on the surface of an allergen (which can be just about anything) as non-self — and this recognition happens because the T-cell is shaped so that the shape on the allergen fits into it like a key into a lock.

So if histones are modified to allow certain kinds of T-cells to be manufactured at enormous rates, then there’s more likely to be a T-cell type that recognises the protein on the surface of, for example, the skin of an apple. And what a T-cell recognises, it wants to kill, so our immune systems kick off. Inflammation starts and all kinds of cells rush into the affected area — which is great, if there’s a nasty bacterium waiting there to wreak havoc. Not so good if we just wanted to eat our apple in peace, and suddenly our throat starts swelling up so we can’t breathe!

The exciting thing is, understanding the role epigenetics plays in allergic reactions gives us another tool to start dealing with allergies. Allergic reactions are becoming more and more of a problem, particularly in industrialised countries, so this is an important development!

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