The neuroimmune network represents a dense network of multiple signals mediated by neurotransmitters, hormones, growth factors, and cytokines produced by multiple lineage cells and is crucial for maintaining neuroimmune homeostasis. Endogenous and exogenous stimuli, which are dangerous to the body, are detected by sensor cells, and they rapidly inform the brain through this network. Innate immunity is thought to play a major role in the neuroimmune network, through cytokines and other mediators released from secretary innate immune cells. Recent research has revealed that innate immunity has its own memory. This is accomplished by metabolic and epigenetic changes. Such changes may result in augmenting immune protection with a risk of excessive inflammatory responses to subsequent stimuli (trained immunity). Alternatively, innate immune memory can induce suppressive effects (tolerance), which may impose a risk of impaired immune defense. Innate immune memory affects the neuroimmune network for a prolonged period, and dysregulated innate immune memory has been implicated with pathogenesis of neuropsychiatric conditions. This chapter summarizes a role of innate immune memory (trained immunity vs. tolerance) in neuroinflammation in association with neuropsychiatric conditions including autism spectrum disorders (ASD).
Part of the book: Cytokines
Autism spectrum disorder (ASD) is a behaviorally defined syndrome with frequent co-morbidities. Evidence indicate a role of innate immunity in ASD pathogenesis. This study addressed whether innate immune abnormalities are associated with ASD co-morbid conditions and/or other clinical co-variables when assessed as changes in monocyte cytokine profiles. This study included 109 ASD (median 11.5 year) and 26 non-ASD subjects (median 11.4 year). Monocyte cytokine profiles were evaluated in association with age/ethnicity, ASD severity, medications, and co-morbidities present in >15% of ASD subjects [gastrointestinal (GI) symptoms, epilepsy, allergic rhinitis, specific antibody deficiency (SAD), and fluctuating behavioral symptoms resembling pediatric acute-onset neuropsychiatric syndrome (PANS)]. ASD severity did not affect frequency of co-morbid conditions. GI symptoms, epilepsy, SAD, and PANS like symptoms revealed associations with changes in production of tumor necrosis factor-α (TNF-α)/soluble TNF-receptor II (sTNFRII), interleukin-1ß (IL-1ß)/IL-6/IL-10, and IL-6, respectively, mostly independent of other co-variables. ASD severity was associated with changes in multiple cytokines but frequently affected by other clinical co-variables. Our findings revealed associations between specific monocyte cytokine profiles and certain co-morbid conditions in ASD subjects, independent of other clinical co-variables. Our findings will aid in assessing treatment options for ASD co-morbidities and their effects on ASD behavioral symptoms.
Part of the book: Autism Spectrum Disorder