Decreased Immune Regulation in Children with ASD Who Experience GI Symptoms
Objectives: To assess immune dysfunction and relationship to behavior in children with ASD with and without GI co-morbidities.
Methods: Over a hundred children participated in our study and were placed into one of four study groups based on responses from two questionnaires: children with ASD who experience GI symptoms of irregular bowel habits (ASDGI) and children with ASD who do not have a history of GI symptoms (ASDNOGI) compared to typically developing children with GI symptoms (TDGI) and typically developing children without a history of GI symptoms (TDNOGI). Peripheral blood mononuclear cells (PBMC) were isolated from participant’s blood, stimulated in-vitro for 24 hrs and supernatants were assessed for cytokine production via Luminex multiplex assays. Behavioral assessments and diagnosis were performed by trained clinicians.
Results: Our data show children in the ASDNOGI group demonstrated elevated innate immune responses, including increased levels of IL-1α, IL-1β and TNFα after stimulation with Toll-Like receptor (TLR)-4 ligands compared to TDNOGI controls. The ASDGI group produced increased levels of the mucosal relevant cytokines IL-5, IL-15 and IL-17 compared to ASDNOGI following TLR-4 stimulation. The production of the regulatory cytokine TGFb1 was decreased in all stimulatory conditions in children with ASDGI compared with children in either ASDNOGI or TDNOGI groups. While diagnostic scores from the ADOS were not different between ASD groups we did find that children in the ASDGI group have worse scores on the Aberrant Behaviors Checklist (ABC) subscales in: Irritability, Hyperactivity and Social Withdrawal. We also report finding positive correlations between TLR-4 stimulated innate cytokines IL-1 α, IL-1β and TNFα and worsening behavioral scores on the ABC.
Conclusions: While immune responses in children with ASD and GI symptoms were generally similar to children with ASD without GI symptoms, we did find evidence of reduced regulatory cytokines and increased mucosal related cytokines in the ASDGI group that may suggest that children with ASD and GI symptoms have a unique imbalance between regulatory and inflammatory pathways.