Immuno-localisation of anti-thyroid antibodies in adult human cerebral cortex

Expression of thyroid-stimulating hormone receptor (TSH-R) has been demonstrated in adipocytes, lymphocytes, bone, kidney, heart, intestine and rat brain. Immuno-reactive TSH-R has been localised in rat brain and human embryonic cerebral cortex but not in adult human brain. We designed a pilot study to determine whether anti-thyroid auto-antibodies immuno-localise in normal adult human cerebral cortex. Forensic samples from the frontal, motor, sensory, occipital, cingulate and parieto-occipito-temporal association cortices were obtained from five individuals who had died of trauma. Although there were no head injuries, the prior psychiatric history of patients was unknown. The tissues were probed with commercial antibodies against both human TSH-R and human thyroglobulin (TG). Anti-TSH-R IgG immuno-localised to cell bodies and axons of large neurones in all 6 regions of all 5 brains. The intensity and percentage of neurones labelled were similar in all tissue sections. TSH-R immuno-label was also observed in vascular endothelial cells in the cingulate gyrus. Although also found in all 5 brains and all six cortical regions, TG localised exclusively in vascular smooth muscle cells and not on neurones. Although limited by the small sample size and number of brain areas examined, this is the first study describing the presence of antigenic targets for anti-TSH-R IgG on human cortical neurons, and anti-TG IgG in cerebral vasculature.