Karolinska Institutet

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Food for Thought – Our Bacteria Are Also Controlled by Epigenetics

Louise Sjöholm has an undergraduate degree in molecular biology as well as a doctorate in depression genetics from the Karolinska Institute. For the last seven years, Louise has worked in the epigenetic field and researches the role of the gastrointestinal tract in relation to autoimmune diseases, i.e. diseases where the body’s own immune system attacks its own tissue. Furthermore, she seeks to broaden our understanding of the epigenetics of bacteria and what connections there are to health and disease.

In my previous post here at Food Pharmacy, I wrote about epigenetics, which to repeat is – the link between inheritance and the environment, in conjunction with their important role in both disease and health. Interestingly, there is more that is affected by the environment (through, for example, what we eat) than just our DNA. This also applies to the bacteria both within and upon our bodies and their genetic coding. They, just as we, are controlled by epigenetic mechanisms.

The epigenetics of bacteria and its connection to diseases is a relatively unexplored area. Quite odd seeing as that, we are in fact only “10% human” – the rest of us is actually made up of bacteria and other microorganisms. We are merely landlords. This, broken down means that, for each cell in our body there are nine times as many microbes in and on us!

There is research which shows that bacteria can actually affect our own epigenome. For example, studies have shown that, that is exactly how the stomach ulcer bacteria Helicobacter pylori works to induce stomach cancer: through epigenetic mechanisms that fight our defense against this bacteria. And even changes within bacterias own epigenomes could potentially contribute to various diseases, due to their basic functions being steered by epigenetic mechanics. Imagine for example, that bacterias production of serotonin, vitamin B12 and vitamin K become disrupted. Surprisingly, some bacterias ability to infect and make us sick (e.g., Escherichia coli, Salmonella and Vibrio) also seem to be partly controlled by epigenetic mechanisms.

My research attempts to, among other things, understand and investigate the epigenetic changes of bacteria, primarily DNA-methylation. This is to determine if there are connections to various diseases. I am developing a new method that can be used to study the most common epigenetic modification of bacteria: methylation of the DNA base A. I hope this new technique will serve as a first screening method and complement the other expensive and more time-consuming methods available. Thus, that we will then be able to understand more about the interaction between us and our bacteria, the tenants.

Perhaps it’s time for us epigeneticists to start studying the remaining 90% of what we call our body?

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