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02 Jul 2019

Is the microbiome the secret to improving our killer cell immunity?

Melbourne researchers have established that the microbiome and its metabolic products promote the way specialised killer immune cells (CD8 T cells) protect us from infections.

Published today in Immunity, University of Melbourne Associate Professor Sammy Bedoui, Immunology Laboratory Head at the Doherty Institute, and study leader, said this discovery could potentially improve cancer immunotherapy and immunisations as these treatments heavily rely on killer T cells.

Microbiota are a large community of microbes that live within us and are actually important for our well-being. Among other things, they produce vital amino acids and vitamins that we depend on. These good microbes also protect us diseases by keeping nasty bacteria in check.

Lead author of the study Dr Annabell Bachem, postdoctoral researcher at the Doherty Institute said their discovery of the link between microbiota and killer T cells is a novel finding, as T cells in immune organs and microbiota exist in different locations and therefore don’t physically meet.

“Discovering that microbiota-derived metabolites that can not only diffuse into immune organs but also improve killer T cells is very exciting,“ she said.

Associate Professor Sammy Bedoui said that a healthy and diverse microbiome and in particular its metabolites were crucial to produce the impact on the immune cells.

“We saw in our experiments that these microbiota-derived metabolites cause dramatic changes in the metabolism of the killer T cells; they change to use their energy in a more sustainable way, which is why they survive better,” Associate Professor Bedoui said.

“Our findings were also remarkable because these ‘survivor’ cells that were promoted by the microbiota and its metabolites are also the ones that have been shown to respond best to immunotherapy.”

Currently only around 40 per cent of cancer patients respond favourably to immunotherapy.

“Having gained deeper insights into the molecular mechanisms of how the microbiota influence the immune system is really exciting. Supported by a research grant from Merck, we can now search for ways of harnessing this process to accelerate the development of new drugs that enhance the efficacy of cancer immunotherapy,” Professor Bedoui said.

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