Shared microbial community changes in female rats and humans with Rett syndrome

Background Rett syndrome (RTT) is an X-linked neurodevelopmental disorder predominantly caused by alterations of the methyl-CpG-binding protein 2 (MECP2) gene. The gut microbiome has been implicated in neurodevelopmental disorders such as Autism Spectrum Disorder (ASD) as a regulator of disease severity. Although the gut microbiome has been previously characterized in humans with RTT, the impact of MECP2 mutation on the composition of the gut microbiome in animal models where the host and diet can be experimentally controlled remains to be elucidated.Methods We evaluated the microbial community through 16S sequencing of fecal samples collected across postnatal development as behavioral symptoms appear and progress in a novel zinc-finger nuclease rat model of RTT. Additionally, we profiled fecal levels of fatty acids in MecP2 deficient rats. Lastly, we compared our results to predicted functional shifts in the microbiota of females with RTT compared to their mothers to further examine the translational potential of the current RTT rat model.Results We have identified microbial taxa that are differentially abundant across key timepoints in a zinc-finger nuclease rat model of RTT compared to WT. Furthermore, we have characterized functional categories of gut microbes that are similarly affected in females with RTT and female RTT rats, including similar alterations in pathways related to short chain fatty acid (SCFA) activity. Lastly, we have demonstrated that SCFA levels are decreased in the feces of RTT rats compared to WT.Limitations The current study is potentially limited by age related differences in the microbiome of RTT participants and controls as well as medication effects on the microbiome. Additionally, the current study did not assess male MeCP2-deficient rats, and it may be relevant in future studies to address potentially disparate microbial changes in male and female rats and humans with RTT.Conclusions The results of our studies establish distinct microbial community shifts that occur in RTT across developmental time points independently of diet or environmental factors. We identify p105 as a key translational timepoint at which microbial shifts most closely mirror reported microbiota communities in RTT patients. Overall, these results represent an important step in translational RTT research.