Background

Autism spectrum disorder (ASD) is characterised by an impairment of social interactions and communication associated with repetitive behaviour and restrictive interests.

Up to 70% of ASD children have gastrointestinal (GI) disorders, which are associated with ASD severity and influenced by feeding disorders. There is also an imbalance in the intestinal microbiota in ASD.

The intestinal microbiota plays a key role in the development and functioning of the brain through the so-called "gut-brain" axis. The gut-brain axis is able to influence inflammation of the brain by altering the barrier between the brain and the blood, known as the blood-brain barrier (BBB), which is essential for proper functioning of the brain. A number of studies have shown that inflammation of the brain and alteration of the BBB are involved in autism.

These phenomena (intestinal dysbiosis, neuroinflammation, and alterations of the BBB) have never been simultaneously explored in ASD patients. It is therefore currently unknown how these different processes interact and participate in autism.

Thus, we would like to know whether an imbalance of the gut microbiota could participate in BBB damage in ASD through neuroinflammation.

Objective

We hypothesize that the composition of the gut microbiota is associated with BBB integrity in ASD.

Thus, the principal aim of this study is to highlight this link.

In addition, we will examine the processes of gut and brain inflammation (gut permeability and inflammation, neuroinflammation, balance of the immune response), as well as the possible influence of the link between the gut microbiota and BBB impairment on certain ASD characteristics, such as ASD severity. The products of the food eaten by the children (called nutrients) will also be analysed, because the way our body assimilates food (the metabolome) can influence the balance of the intestinal microbiota.

Methodology

This is a monocentric, observational, cross-sectional study of 60 children with ASD, aged 6 to 16, living in the Languedoc-Roussillon region and from the ELENA cohort.

We plan to administer three parental questionnaires and carry out a stool analysis, blood test, and clinical examination of the included children.

The stool samples will be collected at home, and the blood test and clinical examination will be performed in the clinical genetics department of the CHU of Montpellier.