ABSTRACT
Many neurological disorders have a distinctive colonic microbiome (CM) signature. Particularly, children with autism spectrum disorders (ASD) exhibit a very dissimilar CM when compared to neurotypical (NT) ones, mostly at the species level. Thus far, knowledge on this matter comes from high-throughput (yet very expensive and time-consuming) analytical platforms, such as massive high-throughput sequencing of bacterial 16S rRNA. Here, pure (260/280 nm, ~1.85) stool DNA samples (200 ng.µL-1) from 48 participants [39 ASD, 9 NT; 3-13 y] were used to amplify four candidate differential CM markers [Bacteroides fragilis (BF), Faecalibacterium prausnitzii (FP), Desulfovibrio vulgaris (DV), Akkermansia muciniphila (AM)], using micro-organism-specific oligonucleotide primers [265 bp (BF), 198 bp (FP), 196 bp (DV), 327 bp (AM)] and a standardized two-step [low (step 1: °Tm-5 °C) to high (stage 2: °Tm-0 °C) astringent annealing] PCR protocol (2S-PCR). The method was sensitive enough to differentiate all CM biomarkers in the studied stool donors [↑ abundance: NT (BF, FP, AM), ASD (DV)], and phylogenetic analysis confirmed the primers' specificity.
ABSTRACT
Introduction: Background: gastrointestinal disorders (GIDs) are common comorbidities in patients with autism spectrum disorders (ASD); treatments with gluten- and casein-free (LGLC) diets or prebiotic/probiotic supplements may reduce the severity of GIDs. Objective: to integrate and discuss the evidence on the effectiveness of LGLC diet therapies and prebiotic/probiotic supplements on GIDs in patients with ASD. Methodology: the guidelines for the publication of systematic reviews and meta-analyses (PRISMA) were used. Participant characteristics, dietary interventions, prebiotic/prebiotic supplementation, effects of interventions on GIDs, risk of bias, and safety of treatments were analyzed. Results: fifteen investigations were analyzed; the prevalence of GIDs among patients with ASD was high (58 %; range, 27-83 %). In more than 20 % of the patients managed with LGLC diets or supplements GID severity decreased (mainly constipation, diarrhea, and abdominal pain). Increases in the counts of beneficial bacteria and a decrease in the proportion of pathogenic bacteria were reported after supplement use. However, all these investigations had significant methodological biases. Conclusions: although reductions in the frequency and severity of some GIDs have been found, the effectiveness of these treatments has not been proven yet. Given the methodological differences in the investigations, the design of rigorous studies to evaluate the therapeutic effects of these treatments on gastrointestinal health in patients with ASD is warranted.
Introducción: Antecedentes: los trastornos gastrointestinales (TGI) son comorbilidades comunes en los pacientes con trastornos del espectro autista (TEA); los tratamientos con dietas libres de gluten y caseína (LGLC) o suplementos de prebióticos/probióticos podrían reducir la severidad de los TGI. Objetivo: integrar y discutir la evidencia sobre la efectividad de las terapias con dietas LGLC y suplementos de prebióticos/probióticos sobre los TGI en pacientes con TEA. Metodología: se utilizaron las guías para la publicación de revisiones sistemáticas y metaanálisis (PRISMA). Se analizaron las características de los participantes, las intervenciones dietéticas, la administración de suplementos de prebióticos/prebióticos, los efectos de las intervenciones sobre los TGI, el riesgo de sesgo de los estudios y la seguridad de los tratamientos. Resultados: se analizaron quince investigaciones; la prevalencia de los TGI entre los pacientes con TEA fue alta (58 %; rango, 27-83 %). En más del 20 % de los pacientes intervenidos con dietas LGLC o suplementos disminuyó la severidad de los TGI (principalmente estreñimiento, diarrea y dolor abdominal). Se reportaron aumentos en los conteos de bacterias benéficas y una disminución de la proporción de bacterias patógenas tras el uso de los suplementos. Sin embargo, todas estas investigaciones presentaron sesgos metodológicos importantes. Conclusiones: aunque se han encontrado reducciones en la frecuencia y severidad de algunos TGI, la efectividad de estos tratamientos aún no se ha comprobado. Dadas las diferencias metodológicas de las investigaciones, se justifica el diseño de estudios rigurosos para evaluar los efectos terapéuticos de estos tratamientos sobre la salud gastrointestinal en pacientes con TEA.
