A team from the Royal Free and University College School of Medicine and St Mark's Hospital, London, England investigated the characteristics of colitis with ileal lymphoid nodular hyperplasia (LNH) in children, and determined whether LNH was specific for autism.
Ileo-colonoscopy was performed in 21 consecutively evaluated children with autistic spectrum disorders and bowel symptoms.
Blinded comparison was made with 8 children with histologically normal ileum and colon, 10 developmentally-normal children with ileal LNH, 15 with Crohn's disease, and 14 with ulcerative colitis.
This is consistent with increasing evidence for gut epithelial dysfunction in autism
|Dr Simon Murch|
The researchers performed immunohistochemistry for cell lineage and functional markers, and histochemistry for glycosaminoglycans and basement membrane thickness.
Histology demonstrated lymphocytic colitis in the autistic children, less severe than classical inflammatory bowel disease. However, basement membrane thickness and mucosal cell density were significantly increased above those of all other groups, including patients with inflammatory bowel disease.
CD8+density and intraepithelial lymphocyte numbers were higher than those in the Crohn's disease, LNH, and normal control groups; and CD3 and plasma cell density and crypt proliferation were higher than those in normal and LNH control groups.
Epithelial, but not lamina propria, glycosaminoglycans were disrupted. However, the epithelium was HLA-DR-, suggesting a predominantly TH2 response.
Dr Simon Murch said on behalf of the group, "Immunohistochemistry confirms a distinct lymphocytic colitis in autistic spectrum disorders, in which the epithelium appears particularly affected. This is consistent with increasing evidence for gut epithelial dysfunction in autism."
In an accompanying Editorial Perspective, William F. Balistreri comments, "This seems to point to gut epithelial dysfunction leading to altered permeability and subsequent entry of central nervous system-altering substances.
"It follows that treatment of the gut disease may affect the CNS disease."