Is autism spectrum disorder (ASD) influenced by the composition of the gut microbiome and the health of the intestinal mucosa?

Currently no one disputes the relationship and interaction between the intestinal microbiome and the brain. Little by little we are better understanding this bidirectional communication between the brain and the intestine, so we know that the microbiome can affect the brain and vice versa. 

Let's see how the following review: «Microbiome–Gut–Mucosal–Immune–Brain Axis and Autism Spectrum Disorder (ASD): A Novel Proposal of the Role of the Gut Microbiome in ASD Aetiology» provides a new vision on autism spectrum disorder (ASD), to do so it studies the relationship between the intestinal microbiome and the brain, through the microbiome-gut-immune system-brain axis, and its influence on the etiology of ASD. It focuses on seeing how imbalances in the intestinal microbiota can influence the pathogenesis of ASD, exploring how inflammation, oxidative stress and neuroendocrine modulation are involved.

This new concept, with a broader and more comprehensive perspective, in which the connection and interaction of the intestinal microbiota, the intestinal mucosa, the immune system and the brain is considered, will take center stage and play a fundamental role in the health and development of the individual. Learning about the connections between the brain, the immune system and the intestine could help in diagnoses and possible new therapies. 

The interaction between all these elements (microbiota, intestinal mucosa, immune system and brain) occurs through different biochemical, immunological and neuronal signals:

• Production of metabolites by the intestinal microbiota.
• Modulation of the intestinal immune response.
• Transmission of nerve signals through the vagus nerve.
• Release of chemical mediators in the brain.

We know that certain diseases can be related to an altered composition of the intestinal microbiome or dysbiosis, such as inflammatory, autoimmune diseases, cancer and obesity, and that errors in the communication pathways between the intestine and the brain can produce neuropsychiatric disorders and affect functions. cerebral. It will be necessary to understand and know the modifications produced both at the cellular and molecular level due to intestinal dysbiosis and in this way help in the development of new therapeutic approaches. 

Alterations in the intestinal microbiota, the intestinal barrier, the immune system and/or the communication between the intestine and the brain can produce communication errors in the axis (MGMI-Brain Axis). Could these communication errors contribute to the etiology and expression of ASD symptoms? 

Let's look at some statements:

• Metabolites produced by bacteria in the intestinal microbiota, such as neurotransmitters and short-chain fatty acids, can influence brain function and behavior. 
• The intestinal microbiota is capable of modulating both immunological and neuroinflammatory responses, affecting both neurological development and brain function. 
• Factors such as inflammation, oxidative stress and neuroendocrine modulation are considered as possible pathways by which alterations in the gut microbiota could play a role in neurodevelopment. 
• Alterations in the intestinal microbiota, such as a microbial imbalance or dysbiosis and increased intestinal permeability, could trigger abnormal immune responses, leading to systemic inflammation and/or activation of immune cells, potentially affecting brain development and behavior.

In the review they took into consideration some research carried out in humans, in some of them associations were obtained between intestinal dysbiosis and greater severity of ASD symptoms, in others connections were found between dysbiosis and risk of ASD, as well as due to genetic and environmental factors. . In those in which interventions were carried out directly on the microbiome, improvements in behavior were obtained.

With all this, the review concludes that the possibility that dysbiosis, intestinal permeability and a dysfunction in the MGMI-Brain Axis communication have a role in the pathogenesis of ASD should be considered, suggesting that they should be taken into account. take into account new therapeutic strategies giving prominence to the composition of the intestinal microbiome.

The close relationship between these systems reveals the need to study and address both mental health and gastrointestinal health in a comprehensive and joint manner.

This makes us wonder if there is a significant variation in the composition of the intestinal microbiota of children with ASD and thus a possible therapeutic route.

Some research suggests that modulating the gut microbiome could have beneficial effects on the health and well-being of people with ASD. These individual interventions would be aimed at modulating the microbiome, focusing on dietary control, the use of probiotics and prebiotics. In this way, the intestinal microbiome would become a potential therapeutic target in cases of ASD.

Article written by Enevia Health Collaborator: Loles Marco 

Graduated in Human Nutrition and Dietetics.

lolesmarcobermudo@gmail.com

Bibliography:

1. De Sales-Millán, Amapola et al. “Microbiome-Gut-Mucosal-Immune-Brain Axis and Autism Spectrum Disorder (ASD): A Novel Proposal of the Role of the Gut Microbiome in ASD Aetiology.” Behavioral sciences (Basel, Switzerland) vol. 13.7 548. June 30, 2023, doi:10.3390/bs13070548
2. Lungba, Rayan M et al. “The Role of the Gut Microbiota and the Immune System in the Development of Autism.” Cureus vol. 12.10 e11226. 28 Oct. 2020, doi:10.7759/cureus.11226