New evidences on the altered gut microbiota in autism spectrum disorders

Francesco Strati,Antonio Calabrò,Joussef Hayek,Duccio Cavalieri,Olivier Jousson,Daniela Renzi,Silvia Leoncini,Davide Albanese,Claudio De Felice,Carlotta De Filippo,Claudio Donati

doi:10.1186/s40168-017-0242-1

Abstract

BackgroundAutism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by social and behavioural impairments. In addition to neurological symptoms, ASD subjects frequently suffer from gastrointestinal abnormalities, thus implying a role of the gut microbiota in ASD gastrointestinal pathophysiology.ResultsHere, we characterized the bacterial and fungal gut microbiota in a cohort of autistic individuals demonstrating the presence of an altered microbial community structure. A fraction of 90% of the autistic subjects were classified as severe ASDs. We found a significant increase in the Firmicutes/Bacteroidetes ratio in autistic subjects due to a reduction of the Bacteroidetes relative abundance. At the genus level, we observed a decrease in the relative abundance of Alistipes, Bilophila, Dialister, Parabacteroides, and Veillonella in the ASD cohort, while Collinsella, Corynebacterium, Dorea, and Lactobacillus were significantly increased. Constipation has been then associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by high levels of bacterial taxa belonging to Escherichia/Shigella and Clostridium cluster XVIII. We also observed that the relative abundance of the fungal genus Candida was more than double in the autistic than neurotypical subjects, yet due to a larger dispersion of values, this difference was only partially significant.ConclusionsThe finding that, besides the bacterial gut microbiota, also the gut mycobiota contributes to the alteration of the intestinal microbial community structure in ASDs opens the possibility for new potential intervention strategies aimed at the relief of gastrointestinal symptoms in ASDs.

Highlights

Autism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by social and behavioural impairments
We characterized the bacterial gut microbiota and the less studied gut mycobiota of subjects affected by autism through ampliconbased metataxonomic analysis of the V3–V5 regions of the prokaryotic 16S ribosomal DNA and of the internal transcribed spacer 1 (ITS1) region of the fungal rDNA in order to better understand the microbial community structure associated with ASDs and its involvement on GI abnormalities
Autistic subjects harbour an altered bacterial gut microbiota For the characterization of the gut microbiota associated with autism, we recruited 40 autistic subjects (36 out of 40 autistic subjects were classified as severe ASDs, Childhood Autism Rating Scale (CARS) value >37) and 40 neurotypical controls (Table 1, Additional file 1: Table S1)

Summary

Introduction

Autism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by social and behavioural impairments. The term “autism spectrum disorders” (ASDs) refers to a group of neurodevelopmental disorders with an early life stage onset characterized by alterations in social interactions and communication and by restricted and repetitive behaviour [1]. It is well accepted the contribution of both genetic and environmental factors in the aetiology of ASDs [2, 3]. We characterized the bacterial gut microbiota and the less studied gut mycobiota of subjects affected by autism through ampliconbased metataxonomic analysis of the V3–V5 regions of the prokaryotic 16S ribosomal DNA and of the internal transcribed spacer 1 (ITS1) region of the fungal rDNA in order to better understand the microbial community structure associated with ASDs and its involvement on GI abnormalities

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