The Immune System, Cytokines, and Biomarkers in Autism Spectrum Disorder

Hydrogen-Rich Water Ameliorates Autistic-Like Behavioral Abnormalities in Valproic Acid-Treated Adolescent Mice Offspring

Due to its anti-inflammatory and anti-oxidative effects, recent research has demonstrated that molecular hydrogen can serve as a new medical approach for depression, anxiety and traumatic brain injury. However, its potential effects on neurodevelopmental diseases, such as autism are still elusive. The present study aims to investigate the potential effects of hydrogen-rich water (HRW) administration on valproic acid (VPA)-induced autistic-like behavioral deficits, and the associated underlying mechanism in adolescent mice offspring. Pregnant ICR mice were randomly divided into five groups (n = 6). One group was injected with saline (NAV group) and provided hydrogen-free water. The other four groups were injected with VPA (600 mg/kg, intraperitoneally, i.p.) on pregnant day (PND) 12.5. One group was provided with hydrogen-free water (VEH group) and the other three groups were provided HRW at different segments, postnatal day 1 (PND 1) to PND 21 (PHV group), PND 13 to PND 21 (PVS group) or from PND 13 to postnatal day 42 (PVL group). Behavioral tests, including open field, novelty suppressed feeding (NSF), hot plate, social interaction (SI) and contextual fear memory tests were conducted between postnatal day 35–42. We found that HRW administration significantly reversed the autistic-like behaviors induced by maternal VPA exposure in the adolescent offspring of both male and female adolescent offspring. Furthermore, HRW administration significantly reversed the alternation of serum levels of interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α), but without any effects on the BDNF levels in maternal VPA-exposed mice offspring. These data suggest the need for additional research on HRW as a potential preventive strategy for autism and related disorders.

Lay Summary: Maternal VPA injection induces autistic-like behavioral deficits in adolescent mice offspring. HRW administration ameliorates autistic-like behavioral deficits. HRW administration reverses the alternation of serum levels of IL-6 and TNF-α induced by VPA.

Social impairments in autism spectrum disorder are related to maternal immune history profile

Maternal immune activation has been highlighted as a factor that might increase the risk and severity of autism spectrum disorder (ASD) in children. Preclinical animal evidence shows that immune activation in mothers during pregnancy causes ASD-like behavioural traits in offspring. To this point, there has been no investigation of whether immune system activation in human mothers during pregnancy is associated with more severe symptoms in children with ASD. In this study, data from an existing ASD cohort (N=220) were analysed to investigate whether immune conditions in the mother were associated with greater severity of autism-related symptoms. Results showed that children whose mothers reported a history of immune activation (allergies and asthma) had significantly higher scores on the Social Responsiveness Scale (SRS; P=0.016), suggesting more severe social impairment symptoms in these children. This increasing severity of social impairment symptoms was further shown on the SRS cognition (P=0.007) and mannerisms (P=0.002) subscales. While immune history was associated with an increase in the severity of social impairment symptoms, history of autoimmune conditions in the mother did not have any effect in this cohort. To the best of our knowledge, this study is the first to show an association between immune activation history in the mother and increased ASD symptom severity in children with ASD. These findings support the idea of an immune system-mediated subtype in ASD, where the immune history of the mother may be an important factor.

Inflammation and Neuro-Immune Dysregulations in Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and interaction and restricted-repetitive patterns of behavior, interests, or activities. Strong inflammation states are associated with ASD. This inflammatory condition is often linked to immune system dysfunction. Several cell types are enrolled to trigger and sustain these processes. Neuro-inflammation and neuro-immune abnormalities have now been established in ASD as key factors in its development and maintenance. In this review, we will explore inflammatory conditions, dysfunctions in neuro-immune cross-talk, and immune system treatments in ASD management.

Immune imbalance of global gene expression, and cytokine, chemokine and selectin levels in the brains of offspring with social deficits via maternal immune activation

The murine maternal immune activation (MIA) offspring model enables longitudinal studies to explore aberrant social behaviors similar to those observed in humans. High levels of cytokines, chemokines and cell adhesion molecules (CAM) have been found in the plasma and/or brains of psychiatric patients. We hypothesized that upregulation of the systemic or brain immune response has an augmenting effect by potentially increasing the interplay between the neuronal and immune systems during the growth of the MIA offspring. In this study, a C57BL/6j MIA female offspring model exhibiting social deficits was established. The expression of fetal interferon (IFN)-stimulated (gbp3, irgm1, ifi44), adolescent immunodevelopmental transcription factor (eg, r2, tfap2b), hormone (pomc, hcrt), adult selectin (sell, selp) and neuroligin (nlgn2) genes was altered. Systemic upregulation of endogenous IL-10 occurred at the adult stage, while both IL-1β and IL-6 were increased and persisted in the sera throughout the growth of the MIA offspring. The cerebral IL-6 levels were endogenously upregulated, but both MCP-1 (macrophage inflammatory protein-1) and L-selectin levels were downregulated at the adolescent and/or adult stages. However, the MIA offspring were susceptible to lipopolysaccharide (LPS) stimulation. After reinjecting the MIA offspring with LPS in adulthood, a variety of sera and cerebral cytokines, chemokines and CAMs were increased. Particularly, both MCP-1 and L-selectin showed relatively high expression in the brain compared with the expression levels in phosphate-buffered saline (PBS)-treated offspring injected with LPS. Potentially, MCP-1 was attracted to the L-selectin-mediated immune cells due to augmentation of the immune response following stimulation in MIA female offspring.

Prenatal paracetamol exposure and child neurodevelopment: A review

BACKGROUND

The non-prescription medication paracetamol (acetaminophen, APAP) is currently recommended as a safe pain and fever treatment during pregnancy. However, recent studies suggest a possible association between APAP use in pregnancy and offspring neurodevelopment.

OBJECTIVES

To conduct a review of publications reporting associations between prenatal APAP use and offspring neurodevelopmental outcomes.

METHODS

Relevant sources were identified through a key word search of multiple databases (Medline, CINAHL, OVID and TOXNET) in September 2016. All English language observational studies of pregnancy APAP and three classes of neurodevelopmental outcomes (autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and intelligence quotient (IQ)) were included. One reviewer (AZB) independently screened all titles and abstracts, extracted and analyzed the data.

RESULTS

64 studies were retrieved and 55 were ineligible. Nine prospective cohort studies fulfilled all inclusion criteria. Data pooling was not appropriate due to heterogeneity in outcomes. All included studies suggested an association between prenatal APAP exposure and the neurodevelopmental outcomes; ADHD, ASD, or lower IQ. Longer duration of APAP use was associated with increased risk. Associations were strongest for hyperactivity and attention-related outcomes. Little modification of associations by indication for use was reported.

CONCLUSIONS

Together, these nine studies suggest an increased risk of adverse neurodevelopmental outcomes following prenatal APAP exposure. Further studies are urgently needed with; precise indication of use and exposure assessment of use both in utero and in early life. Given the current findings, pregnant women should be cautioned against indiscriminate use of APAP. These results have substantial public health implications.

Serum Cytokine and Growth Factor Levels in Children with Autism Spectrum Disorder

BACKGROUND The immune system may have a role in the pathogenesis of autism spectrum disorder (ASD), including typical and atypical autism. The aim of this study was to determine whether a cytokine and growth factor panel could be identified for the diagnosis and prognosis in children with ASD, including typical and atypical autism. MATERIAL AND METHODS This study included 26 children with ASD (typical or atypical) and 11 of their siblings who did not have ASD. A panel of ten serum cytokines and growth factors were investigated using addressable laser bead assay (ALBIA) and enzyme-linked immunosorbent assay (ELISA) kits. Results were correlated with scores using the Childhood Autism Rating Scale (CARS) and Autism Diagnostic Observation Schedule (ADOS) for the children with ASD and compared with the findings from their siblings without ASD. RESULTS There were no statistically significant differences in serum cytokine and growth factor levels between children with ASD and their siblings. The scores using CARS and ADOS were significantly greater in children with typical autism compared with children with atypical autism as part of the ASD spectrum. Serum levels of cytokines and growth factors showed a positive correlation with CARS and ADOS scores but differed between children with typical and atypical autism and their siblings. CONCLUSIONS The findings of this study showed that serum measurement of appropriately selected panels of cytokines and growth factors might have a role in the diagnosis of ASD.

Systemic inflammation in asocial BTBR T+ tf/J mice predisposes them to increased psoriatic inflammation

Autistic Spectrum disorder (ASD) is a neurobehavioral disorder characterized by defects in communication skills leading to restricted sociability. ASD has immense dysregulation in immune responses which is thought to affect neuronal system and thus behavior. ASD patients and BTBR T⁺ tf/J (BTBR) autistic mice have increased systemic inflammation due to dysfunction in innate and adaptive immune responses. Recent studies suggest that ASD patients are associated with several co-morbid autoimmune disorders including psoriasis. However underlying mechanisms for this phenomenon have not been explored. In this study, we used imiquimod (IMQ)-induced psoriatic inflammation in social C57BL/6 (C57) mice and asocial BTBR mice to investigate whether systemic inflammation in BTBR is associated with increased susceptibility to psoriatic inflammation. Our data shows that BTBR mice have increased expression of TLR7/IL-6/IL-23 in systemic DCs but not in skin as compared to C57 mice at baseline. This leads to much greater psoriatic inflammation in BTBR mice upon IMQ application than C57 mice. Consequently, BTBR mice also have higher Th17 related immune responses in the skin and systemic compartment. Overall our study suggests that systemic innate (TLR7/IL-23/IL-6 in DCs) and adaptive (Th17 related signaling) immune responses are heightened in BTBR mice at baseline which predisposes them for greater psoriatic inflammation than C57 mice upon IMQ application. This could be one of the reasons for increased psoriatic inflammation in patients with ASD. Therapies that aim to decrease immune activation may not only benefit ASD-associated neurobehavioral abnormalities but also comorbid disorders such as psoriasis.

Alterations in plasma cytokine levels in chinese children with autism spectrum disorder

Genetic alterations, together with environmental risk factors during infancy and childhood, contribute significantly to the etiology of autism spectrum disorder (ASD), a heterogeneous neurodevelopmental condition characterized by impairments in social interaction and restricted, repetitive behaviors. Mounting evidence points to a critical contribution of immunological risk factors to the development of ASD. By affecting multiple neurodevelopmental processes, immune system dysfunction could act as a point of convergence between genetics and environmental factors in ASD. Previous studies have shown altered cytokine levels in individuals with ASD, but research in Asian populations are limited. Here, we measured the plasma levels of 11 candidate cytokines in ASD and typically developing (TD) children. The cohort included 41 TD children and 87 children with ASD, aged 1-6 years. We found that as compared to the TD group, children with ASD had higher plasma levels of Eotaxin, TGF-β1 and TNF-α. The increase in TGF-β1 level was most significant in males, while the increase in Eotaxin was most significant in females. Eotaxin level negatively correlated with the social affect score (SA) in ADOS, while TNF-α level positively correlated with total development quotient (DQ), measured using GMDS. These pilot findings suggest potentially important roles of Eotaxin, TGF-β1 and TNF-α in ASD in the Chinese population. Autism Res 2018, 11: 989-999. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Alteration of immune system function is an important risk factor for autism spectrum disorder (ASD). Here we found that the levels of cytokines, including Eotaxin, TGF-β1 and TNF-α, are elevated in Chinese children with ASD, as compared to typically developing children. The change in TGF-β1 level was most prominent in boys, while that of Eotaxin was more significant in girls. These results provide evidence for changes in cytokine profile in Chinese children with ASD.

Children With Autism Spectrum Disorder With Regression Exhibit a Different Profile in Plasma Cytokines and Adhesion Molecules Compared to Children Without Such Regression

Background: In the etiopathogenesis of autism spectrum disorder (ASD), it has been suggested that a proinflammatory condition, as well as an alteration in adhesion molecules in the early stages of neurodevelopment, may play a role in the pathophysiology of the disorder. This study set out to evaluate the plasma levels of certain inflammatory cytokines, adhesion molecules, and growth factors in a sample of pediatric patients with ASD and compare them to the levels in a control group of healthy children. Methods: Fifty-four children (45 males and nine females) aged 2-6, who were diagnosed with ASD, and a control group of 54 typically-developing children of similar ages were selected. The diagnosis of ASD was carried out in accordance with the DSM-5 criteria and the data obtained from a developmental semi-structured clinical interview and the ADOS evaluation test. Additional testing was carried out to identify the children's developmental level and severity of ASD symptomatology. Patients with ASD were further divided into two subgroups based on developmental parameters: ASD children with neurodevelopmental regression (AMR) and ASD children without neurodevelopmental regression (ANMR). Analyses of plasma molecules, such as cathepsin, IL1β, IL6, IL8, MPO, RANTES, MCP, BDNF, PAI NCAM, sICAM, sVCAM and NGF, were performed. Results: Higher levels of NGF were observed in the ASD group compared with the levels in the control group (p < 0.05). However, in the analysis of the ASD subgroups, lower plasma levels of NCAM and higher levels of NGF were found in the group of ASD children without developmental regression compared to the levels in the group of typically-developing children. Conclusions: These results suggest differences that could be related to different pathophysiological mechanisms in ASD. There is not a specific profile for the expression of relevant plasma cytokines, adhesion molecules or growth factors in children with ASD compared with that in typically-developing children. However, in the ANMR and AMR subgroups, some of the adhesion molecules and neuronal growth factors show differences that may be related to synaptogenesis.

Neuroimmune and Inflammatory Signals in Complex Disorders of the Central Nervous System

An extensive microglial-astrocyte-monocyte-neuronal cross talk seems to be crucial for normal brain function, development, and recovery. However, under certain conditions neuroinflammatory interactions between brain cells and neuroimmune cells influence disease outcome and brain pathology. Microglial cells express a range of functional states with dynamically pleomorphic profiles from a surveilling status of synaptic transmission to an active player in major events of development such as synaptic elimination, regeneration, and repair. Also, inflammation mediates a series of neurotoxic roles in neuropsychiatric conditions and neurodegenerative diseases. The present review discusses data on the involvement of neuroinflammatory conditions that alter neuroimmune interactions in four different pathologies. In the first section of this review, we discuss the ability of the early developing brain to respond to a focal lesion with a rapid compensatory plasticity of intact axons and the role of microglial activation and proinflammatory cytokines in brain repair. In the second section, we present data of neuroinflammation and neurodegenerative disorders and discuss the role of reactive astrocytes in motor neuron toxicity and the progression of amyotrophic lateral sclerosis. In the third section, we discuss major depressive disorders as the consequence of dysfunctional interactions between neural and immune signals that result in increased peripheral immune responses and increase proinflammatory cytokines. In the last section, we discuss autism spectrum disorders and altered brain circuitries that emerge from abnormal long-term responses of innate inflammatory cytokines and microglial phenotypic dysfunctions.

Modulation of Immunological Pathways in Autistic and Neurotypical Lymphoblastoid Cell Lines by the Enteric Microbiome Metabolite Propionic Acid

Propionic acid (PPA) is a ubiquitous short-chain fatty acid which is a fermentation product of the enteric microbiome and present or added to many foods. While PPA has beneficial effects, it is also associated with human disorders, including autism spectrum disorders (ASDs). We previously demonstrated that PPA modulates mitochondrial dysfunction differentially in subsets of lymphoblastoid cell lines (LCLs) derived from patients with ASD. Specifically, PPA significantly increases mitochondrial function in LCLs that have mitochondrial dysfunction at baseline [individuals with autistic disorder with atypical mitochondrial function (AD-A) LCLs] as compared to ASD LCLs with normal mitochondrial function [individuals with autistic disorder with normal mitochondrial function (AD-N) LCLs] and control (CNT) LCLs. PPA at 1 mM was found to have a minimal effect on expression of immune genes in CNT and AD-N LCLs. However, as hypothesized, Panther analysis demonstrated that 1 mM PPA exposure at 24 or 48 h resulted in significant activation of the immune system genes in AD-A LCLs. When the effect of PPA on ASD LCLs were compared to the CNT LCLs, both ASD groups demonstrated immune pathway activation, although the AD-A LCLs demonstrate a wider activation of immune genes. Ingenuity Pathway Analysis identified several immune-related pathways as key Canonical Pathways that were differentially regulated, specifically human leukocyte antigen expression and immunoglobulin production genes were upregulated. These data demonstrate that the enteric microbiome metabolite PPA can evoke atypical immune activation in LCLs with an underlying abnormal metabolic state. As PPA, as well as enteric bacteria which produce PPA, have been implicated in a wide variety of diseases which have components of immune dysfunction, including ASD, diabetes, obesity, and inflammatory diseases, insight into this metabolic modulator may have wide applications for both health and disease.

Tics and Tourette: a clinical, pathophysiological and etiological review

PURPOSE OF REVIEW

Describe developments in the etiological understanding of Tourette syndrome.

RECENT FINDINGS

Tourette syndrome is a complex heterogenous clinical syndrome, which is not a unitary entity. Pathophysiological models describe gamma-aminobutyric acid-ergic-associated disinhibition of cortico-basal ganglia motor, sensory and limbic loops. MRI studies support basal ganglia volume loss, with additional white matter and cerebellar changes. Tourette syndrome cause likely involves multiple vulnerability genes and environmental factors. Only recently have some vulnerability gene findings been replicated, including histidine decarboxylase and neurexin 1, yet these rare variants only explain a small proportion of patients. Planned large genetic studies will improve genetic understanding. The role of inflammation as a contributor to disease expression is now supported by large epidemiological studies showing an association with maternal autoimmunity and childhood infection. Investigation of blood cytokines, blood mRNA and brain mRNA expression support the role of a persistent immune activation, and there are similarities with the immune literature of autistic spectrum disorder. Current treatment is symptomatic, although there is a better appreciation of factors that influence treatment response.

SUMMARY

At present, therapeutics is focused on symptom-based treatments, yet with improved etiological understanding, we will move toward disease-modifying therapies in the future.