Role of the Gut Vascular Barrier and Microbiota in Autism Spectrum Disorders

Role of the Gut Vascular Barrier and Microbiota in Autism Spectrum Disorders: Evaluation of Efficacy of Postbiotic-based Nutraceutical Treatment

Recent research links gut microbiota alterations to Autism Spectrum Disorders (ASD), a neurobiological condition with multifactorial bases. In some ASD patients, altered gut flora and increased intestinal permeability are observed, influencing the central nervous system's development and function. Chronic gastrointestinal (GI) symptoms are commonly associated with ASD and correlate with its severity. This non-pharmacological interventional clinical study aims to investigate the role of gut microbiota on ASD and the effectiveness of postbiotic-based dietary supplements in children aged 3-8 years old. Gastrointestinal symptoms, behavioral profile and analysis of intestinal metagenomic and metabolomic profiles will be assessed before and after one-month treatment. The results of the study could enhance understanding of non-pharmacological therapeutic approaches in ASD and improve clinical management strategies and the behavioural functioning for children with ASD.

Modulating the microbiota could be an effective way to improve gastrointestinal issues and related behavioral symptoms in children with ASD, offering new treatment avenues. There is particular interest in alternatives to fecal microbiota transplantation, such as postbiotic supplements, which contain molecules naturally released during microbiota metabolism.

These molecules can regulate intestinal homeostasis and microbe-host interactions generating health benefits, possess anti-inflammatory and immunomodulatory activities, and contribute to the barrier activity of the intestinal epithelium. In line with findings for other nutraceutical therapies, dietary supplementation with postbiotics could resolve bowel problems in children with ASD and have positive consequences on behavioral regulation; however, the data collected in the literature is still scarce and limited to studies on mouse models of ASD.

This non-pharmacological clinical study, part of a collaboration between Fondazione IRCCS Istituto Neurologico Carlo Besta (FINCB) and Istituto Clinico Humanitas (ICH), evaluates postbiotic-based supplements' impact on gut microbiota's role in ASD.

Stool samples will be collected from patients at FINCB and FDG, and transported to ICH for analysis of the intestinal bacterial community and intestinal permeability. Participants will then receive a postbiotic-based dietary supplement. After treatment, changes in bowel habits, intestinal bacteria characteristics, intestinal permeability, and any behavioral changes will be evaluated.

Existing literature highlights the protective effects of postbiotics derived from Lactobacillus paracasei CNCM I-5220 on the intestine, specifically contributing to the maintenance of intestinal barrier integrity and protection against leaky gut syndrome.

Unlike probiotics, it provides immediate benefits without live bacteria risks, offering a safe alternative for fragile populations. PostbiotiX Comfort®, which includes the same fermented FOS by L. paracasei found in various infant food supplements (such as Smart D3 Matrix, Polivit Immuno Matrix, and Idra Matrix), will be utilized in this study. These products have been safely used in other formulations without any recorded safety concerns and have demonstrated an excellent toxicological profile.

Inclusion Criteria:

• Group 1 and 2:

Inclusion criteria

• Diagnosis of ASD according to DSM-5 diagnostic criteria;
• Clinical neurological evaluation by child neurologist and neuropsychologist with administration of standardized instruments such as Autism Diagnostic Observation Schedule-2 (ADOS-2) and/or Autism Diagnostic Interview-Revised (ADI-R) to support diagnosis;
• Assessment of psychomotor or intellectual development (Griffiths Scales, Wechsler Scales, Leiter Scale)
• Assessment of the following symptoms in the past three months: constipation, diarrhea, abnormal stool consistency, abnormal stool smell, flatulence, abdominal pain, unexplained daytime irritability, and nighttime awakening, and abdominal tenderness. The degree of gastrointestinal disturbances will be quantified before recruitment using an Italian version of the GI Severity Index. A score of at least 2 in a single item of gastrointestinal symptoms (item 1-6) was required for entry into the symptomatic group.
• Signed informed consent for analysis of intestinal microbiota and metabolome and administration of nutraceutical therapy with PostbiotiX Comfort ®.

Group 3 Inclusion criteria

• Males or females aged between 3 and 8 years whit typical development and absence of gastrointestinal symtomps
• Signed informed consent for analysis of intestinal microbiota and metabolome

Exclusion Criteria:

Group 1 and 2

• Exclusion Criteria
• Children with syndromic ASD or defined genetic diseases;
• Subjects with significant health problems requiring surgical treatment or continuous medical; treatment;
• Severe gastrointestinal problems requiring immediate (life-threatening) treatment;
• Severely underweight/malnourished children;
• Use of medications that may affect biomarkers assessed, for example: antibiotics and/or pre-, probiotics within 1 month prior to enrollment.

Group 3 exclusion criteria

- Participants with gastrointestinal problems requiring immediate (life-threatening) treatment, or with gastrointestinal symptoms such as chronic irregular bowel movements (constipation, diarrhea), encopresis, recurrent abdominal bloating and pain, gastroesophageal reflux and vomiting, or food aversion.