Retinitis pigmentosa is associated with shifts in the gut microbiome

Abstract Background: The gut microbiome is known to influence the pathogenesis and progression of neurodegenerative diseases. However, there has been relatively little focus upon the implications of the gut microbiome in retinal diseases such as retinitis pigmentosa (RP) that leads to photoreceptor degeneration and is the main worldwide cause of complete blindness in adulthood. Here, we investigated changes in gut microbiome composition linked to RP, by assessing both retinal degeneration and gut microbiome in the rd10 mouse model of RP as compared to control C57BL/6J mice.Results: In rd10 mice, retinal responsiveness to flashlight stimuli was deteriorated with respect to observed in age-matched control mice, with decreased amplitudes in the a- and b-wave responses of the electroretinogram and concomitant reduction of the visual acuity. This functional decline in dystrophic animals was accompanied by photoreceptor loss, evidenced by decreased outer nuclear layer thickness, and morphologic anomalies in photoreceptor cells. Changes in retinal neurons were paralleled to induction of reactive gliosis in retina, with increased microglial cell numbers and higher Müller cell reactivity in rd10 mice. Furthermore, 16S rRNA gene amplicon sequencing data showed a microbial gut dysbiosis with differences in alpha and beta diversity at the genera, species and amplicon sequence variants (ASV) levels between dystrophic and control mice. A taxonomic partitioning of ASV was observed since unique ASVs present in only one group had a cumulative relative microbial abundance between 17.6% (rd10 mice) and 26.7% (C57BL/6J mice). Remarkably, four fairly common ASV in healthy gut microbiome belonging to -Rikenella spp., Muribaculaceace spp., Prevotellaceae UCG-001 spp., and Bacilli spp.- were absent in the gut microbiome of retinal disease mice, while Bacteroides caecimuris was significantly enriched in mice with retinitis pigmentosa. Conclusions: Our results indicate that retinal degenerative changes in retinitis pigmentosa are linked to relevant gut microbiome changes. The findings suggest that microbiome shifting could be considered as potential biomarker and therapeutic target for retinal degenerative diseases.