Overexpression of S100β within the cerebral cortex in autism

Introduction: Neuroglial activation and ‘neuroinflammation’ have been previously reported in cases with ASD (Vargas et al. Ann Neurol 2005; 57: 67). We examined glial cell activation within the cerebral cortex of an established cohort of cases (forming part of the Autism Tissue Program (ATP) ‘Brain Atlas Project’).Material and methods: 200-lm-thick formalin-fixed, celloidin-embedded brain tissue slices (Brodmann Areas 17, 21, 22, 24, 32, 44, 45) from eight ASD cases (ages 4–67) and eight neurologically normal cases (ages 4–75), obtained with ethical approval through the ATP (USA), were embedded in paraffin, serially resectioned (10 lm), immunolabelled with CD68, MHC II, GFAP and S100β (Dako, Ely, UK), and processed for quantitative image analysis using Image-Pro Plus software (Media Cybernetics, Marlow, UK). Data were analysed using multi-level statistical models (GLM, GEE) to determine group effects.Results: Varying degrees of glial activation were found within the cortical white matter in ASD cases, whereas microglial activation was largely absent within the cortical grey matter. Significantly greater numbers of S100β+ve cells were found in ASD in all cortical regions.Conclusions: Overexpression of S100β (a calcium-binding protein restricted to astrocytes in the brain), although not directly associated with neuroinflammation, and reported in a number of other brain disorders, represents an important consistent finding in these ASD cases