Gut bacteria could play a role in eye disease, study finds

Gut bacteria could be contributing to a group of eye diseases that can cause loss of vision and even blindness, researchers from Sun Yat-sen University and University College London have found. That means the diseases could potentially be treated with antibiotics, according to the study published in peer-reviewed journal Cell on February 26. The eye diseases – known as inherited retinal degenerations – have more than 250 associated genes. “The onset of [disease] typically varies from birth to early adulthood, with lifelong implications for patients and their families,” said the research team, led by Professor Wei Lai from Sun Yat-sen University in Guangzhou and Professor Richard Lee from UCL. One gene found to cause this type of eye disease has been identified as the Crumbs homology 1, or CRB1 – and that is where the researchers found a link to gut bacteria. “We found CRB1 was expressed both in the retinal pigment epithelium (RPE) and in the gut,” the paper said, referring to the pigmented layer of the retina. Inherited retinal degenerations have long been considered solely genetic eye conditions. But during their eight-year study, the researchers found that the CRB1 gene was expressed not just in the retinal barrier, but also in the epithelium – a thin, protective layer of cells – of the colon. The gene plays a key role in maintaining barriers in both the eyes and the gut. If there is a mutation that affects the gene they are vulnerable, and bacteria could travel from the lower gastrointestinal tract to the retina through the bloodstream, causing loss of vision. Gene therapy is used as the main treatment for CRB1-linked retinal degenerations to try to reintroduce normal gene expression. But in the study, the scientists found in experiments on mice that antibiotics could clear out the bacteria and stop the eye disease from progressing. They said antibiotics would not repair damage to the eyes but they could help treat the disease. The connection between the gut microbiome and other organs in the body, including the brain, has increasingly been in the spotlight in recent decades, with researchers highlighting the link between gut health and overall health. The latest study findings could have “broader significance”, Wei said in the paper. “We believe that this mechanism could also exist in other retinal diseases,” he said, referring to bacteria reaching the eye from the gut.