Diversity of gut microbiota in autism reveals differential abundance of various bacterial species-CME medical conference 2017
Gut microbiome play an important role in early development and predisposition to disease. Gut-Brain axis provides bidirectional communicational route; imbalance of which can have pathophysiological consequences. Various factors play a role in the development of the gut microbiome. Gut dysbiosis is a frontier in autism research and affects 85% of autistic children (NIH report). Their microbiome typically has few overall microbes and smaller number of health promising microbes than their neurotypical peers. In view of this we have made an attempt to check the hypothesis that the gut microbes affect the brain thus altering the behaviour of an individual.
Materials and Methods: 16s rRNA sequence of autism samples were retrieved from the American Gut Project Archive. Taxonomic assignment was inferred by similarity based identification and clustering methods using Quantitative Insights Into Microbial Ecology (QIIME). With the taxonomic assignment of the sequences, species abundance was characterized and co-occurrence network was built to infer species interaction. Also measures of diversity- α(within) and β(between) was performed to identify species abundance and to find exclusive bacterial species present in autistic subjects. Statistical parameters such as mean, standard deviation, distance matrix were considered to validate the significance of the result obtained.
Result: Various bacteria such as Ruminococcus sp., Bifidobacterium sp., Prevotella sp., Coprococcus sp., Sutterella sp., Luminococcus sp., Desulfovibrionaceace sp. have been found to be with varying abundance in autistic subjects when compared to normal individuals. Phylogenetic analysis revealed distinct bacterial families with varied species abundance within and across samples. Co-occurrence network for overlapping bacterial species in autism indicated interplay of various genes whose functioning is annexed to autistic gut.
These findings indicate the connecting link between gut-microbiome-brain-axis and the autistic behaviour which provide better means of diagnosis and treatment.