Immunological Dysfunction in Tourette Syndrome and Related Disorders

Abstract

Chronic tic disorder and Tourette syndrome are common childhood-onset neurological diseases. However, the pathophysiology underlying these disorders is unclear, and most studies have focused on the disinhibition of the corticostriatal-thalamocortical circuit. An autoimmune dysfunction has been proposed in the pathogenetic mechanism of Tourette syndrome and related neuropsychiatric disorders such as obsessive-compulsive disorder, autism, and attention-deficit/hyperactivity disorder. This is based on evidence from animal model studies and clinical findings. Herein, we review and give an update on the clinical characteristics, clinical evidence, and genetic studies in vitro as well as animal studies regarding immune dysfunction in Tourette syndrome.

Keywords: PANDAS; Tourette syndrome; basal ganglia; immunological dysfunction; neuroinflammation.

Figure 1

Summary of the possible underlying mechanism leading to immune dysfunction in Tourette syndrome. Predisposing conditions include dysfunction of dopamine metabolism (hyperdopaminergic state) and genetic susceptibility. External triggers such as allergen and pathogen may also, in part, facilitate periphery and brain immune dysregulation. In the periphery, reduced regulatory cells (which might be facilitated by the hyperdopaminergic state), increased release of proinflammatory cytokines, and activation of T-cells and B-cells may lead to reduced immune tolerance. Additionally, the decreased IgG3 level may lead to a defective immune response to pathogens, hence resulting in persistent inflammation. In the brain, regulation of immune-related genes in localized inflammatory microglial activation in the striatum in TS may result in neuroinflammation and additionally affect neuronal survival and abnormalities in neurogenesis. However, the production of any specific pathogenic autoantibody remains to be explored.