Gut flora and AMD

The composition of the gut microbiome may have an impact on the development of age-related macular degeneration (AMD), thereby opening up potential new avenues of research and therapeutic strategies, according to Swiss researcher Martin S Zinkernagel MD, PhD. “We know that diet has an impact on the gut microbiome, which may constitute a link between nutrition and the development of AMD. The impact of specific bacterial species on the development of experimental choroidal neovascularisation is currently being investigated. Future treatments for AMD may well target the composition of the gut microbiome,” he told the 17th EURETINA Congress in Barcelona. The intestinal microbiome forms a complex ecosystem of up to 100 trillion microbes per individual, with the human body containing roughly as many bacteria as human cells, said Dr Zinkernagel, Bern University Hospital, Switzerland. “To date, more than 10,000 bacteria species have been identified in the gut, and there are approximately 100 times more genes in the gut microbiome than human genes, so there are a vast number of organisms residing there,” he said. The intestinal gut flora plays a major role in the degradation and digestion of nutrition and is a fundamental component of human physiology. Changes in the microbiome can trigger changes in human cellular activities and contribute to the development of metabolic diseases such as diabetes or atherosclerosis, said Dr Zinkernagel. MULTIFACTORIAL DISEASE He noted that AMD is a multifactorial disease in which nutrition and genetics are known to play a role, although very few studies have specifically targeted the gut microbiome as a potential contributory factor to the progression of the disease. He said that one recent study, however, showed that high-fat diets exacerbate choroidal neovascularisation in a mouse model by increasing the relative abundance of the phylum Firmicutes in the gut microbiome. To explore this link further, Dr Zinkernagel initiated a pilot study of 12 patients with neovascular AMD and 11 age-matched controls without AMD to establish whether the compositional and functional diversity of the intestinal microbiome is associated with neovascular AMD. After sequencing the intestinal metagenomes of both sets of patients, the results showed an enrichment of certain microbial genera, namely oscillibacter, anaerotruncus, eubacterium ventriosum and ruminococcus torques in AMD patients versus bacteroides eggerthii in controls. The next step for Dr Zinkernagel and his research team is to validate these results in a larger study. He concluded that the findings may ultimately open a significant field of research and therapeutic development if the observations lead to opportunities for beneficial modification of the microbiome to alter the course of the retinal pathology. Martin S Zinkernagel: martin.zinkernagel@insel.ch

Tags: gut bacteria