Modifying the gut microbiota to protect the ageing eye and brain.

As we age, cellular and molecular changes in the eye and the brain lead to worsening vision and memory, and increase our risk of developing dementias. This presents a huge public healthcare and economic challenge in our increasingly aged population. These age-associated changes are regulated by our immune system which in turn is strongly influenced by the vast community of microbes living within our gut (the gut microbiota). Changes in the composition and function of the gut microbiota have been linked with declining brain health, with recent studies implicating microbial modulation of signalling between the gut and the immune system (the ‘gut-immune-brain axis’). Growing evidence also supports a role for microbial involvement in age-associated eye diseases. I have recently shown that transferring gut microbiota from young donor mice to aged mice can reverse some of the detrimental inflammatory changes of ageing in the gut, the immune system, the brain, and the eye. In this proposal I will define which components of the microbiota transfers are responsible for these beneficial effects in aged recipients. Specifically, I will establish whether the whole microbiota community, specific microbes, or specific microbial products are responsible for improving brain and eye function and determine how they exert their effects. Ultimately, this work will establish how we can modify the aged gut microbiota to protect against both cognitive and visual decline in later life, and potentially protect people at risk from progression to sight loss and dementias.