Differential monocyte responses to TLR ligands in children with autism spectrum disorders

Targeting gut microbiome: A novel and potential therapy for autism

Autism spectrum disorder (ASD) is a severely neurodevelopmental disorder that impairs a child's ability to communicate and interact with others. Children with neurodevelopmental disorder, including ASD, are regularly affected by gastrointestinal problems and dysbiosis of gut microbiota. On the other hand, humans live in a co-evolutionary association with plenty of microorganisms that resident on the exposed and internal surfaces of our bodies. The microbiome, refers to the collection of microbes and their genetic material, confers a variety of physiologic benefits to the host in many key aspects of life as well as being responsible for some diseases. A large body of preclinical literature indicates that gut microbiome plays an important role in the bidirectional gut-brain axis that communicates between the gut and central nervous system. Moreover, accumulating evidences suggest that the gut microbiome is involved in the pathogenesis of ASD. The present review introduces the increasing evidence suggesting the reciprocal interaction network among microbiome, gut and brain. It also discusses the possible mechanisms by which gut microbiome influences the etiology of ASD via altering gut-brain axis. Most importantly, it highlights the new findings of targeting gut microbiome, including probiotic treatment and fecal microbiota transplant, as novel and potential therapeutics for ASD diseases.

Toll-like receptors, NF-κB, and IL-27 mediate adenosine A2A receptor signaling in BTBR T+ Itpr3tf/J mice

Autism is a predominant neurodevelopmental disorder characterized by impaired communication, social deficits, and repetitive behaviors. Recent research has proposed that the impairment of innate immunity may play an important role in autism. Toll-like receptors (TLRs) are potential therapeutic targets against neuroinflammation. The BTBR T⁺ Itpr3^tf/J (BTBR) mouse is a well-known model of autism, showing repetitive behaviors such as cognitive inflexibility and increased grooming as compared to C57BL/6 (B6) mice. Adenosine A2A receptor (A2AR) signaling is involved in inflammation, brain injury, and lymphocyte infiltration into the CNS, but the role of A2AR in autism remains unknown. We investigated the effect of A2AR antagonist SCH 5826 (SCH) and agonist CGS 21680 (CGS) on the expression levels of TLRs, IL-27, NF-κB p65, and IκBα in BTBR mice. Treatment of BTBR mice with SCH increased the percentage of splenic CD14⁺TLR2⁺ cells, CD14⁺TLR3⁺ cells, CD14⁺TLR4⁺ cells, and decreased the percentage of CD14⁺IL-27⁺ cells, as compared to the untreated BTBR mice. Our results reveal that BTBR mice treated with CGS had reversal of SCH-induced immunological responses. Moreover, mRNA and protein expression analyses confirmed increased expression of TLR2, TLR3, TLR4, and NF-κB p65 in brain tissue, and decreased IL-27 and IκBα expression following SCH treatment, as compared to the untreated-BTBR and CGS-treated BTBR mice. Together, these results suggest that the A2AR agonist corrects neuroimmune dysfunction observed in BTBR mice, and thus has the potential as a therapeutic approach in autism.

The putative role of environmental aluminium in the development of chronic neuropathology in adults and children. How strong is the evidence and what could be the mechanisms involved?

The conceptualisation of autistic spectrum disorder and Alzheimer's disease has undergone something of a paradigm shift in recent years and rather than being viewed as single illnesses with a unitary pathogenesis and pathophysiology they are increasingly considered to be heterogeneous syndromes with a complex multifactorial aetiopathogenesis, involving a highly complex and diverse combination of genetic, epigenetic and environmental factors. One such environmental factor implicated as a potential cause in both syndromes is aluminium, as an element or as part of a salt, received, for example, in oral form or as an adjuvant. Such administration has the potential to induce pathology via several routes such as provoking dysfunction and/or activation of glial cells which play an indispensable role in the regulation of central nervous system homeostasis and neurodevelopment. Other routes include the generation of oxidative stress, depletion of reduced glutathione, direct and indirect reductions in mitochondrial performance and integrity, and increasing the production of proinflammatory cytokines in both the brain and peripherally. The mechanisms whereby environmental aluminium could contribute to the development of the highly specific pattern of neuropathology seen in Alzheimer's disease are described. Also detailed are several mechanisms whereby significant quantities of aluminium introduced via immunisation could produce chronic neuropathology in genetically susceptible children. Accordingly, it is recommended that the use of aluminium salts in immunisations should be discontinued and that adults should take steps to minimise their exposure to environmental aluminium.

Developmental disruption of amygdala transcriptome and socioemotional behavior in rats exposed to valproic acid prenatally

Background

The amygdala controls socioemotional behavior and has consistently been implicated in the etiology of autism spectrum disorder (ASD). Precocious amygdala development is commonly reported in ASD youth with the degree of overgrowth positively correlated to the severity of ASD symptoms. Prenatal exposure to VPA leads to an ASD phenotype in both humans and rats and has become a commonly used tool to model the complexity of ASD symptoms in the laboratory. Here, we examined abnormalities in gene expression in the amygdala and socioemotional behavior across development in the valproic acid (VPA) rat model of ASD.

Methods

Rat dams received oral gavage of VPA (500 mg/kg) or saline daily between E11 and 13. Socioemotional behavior was tracked across development in both sexes. RNA sequencing and proteomics were performed on amygdala samples from male rats across development.

Results

Effects of VPA on time spent in social proximity and anxiety-like behavior were sex dependent, with social abnormalities presenting in males and heightened anxiety in females. Across time VPA stunted developmental and immune, but enhanced cellular death and disorder, pathways in the amygdala relative to saline controls. At postnatal day 10, gene pathways involved in nervous system and cellular development displayed predicted activations in prenatally exposed VPA amygdala samples. By juvenile age, however, transcriptomic and proteomic pathways displayed reductions in cellular growth and neural development. Alterations in immune pathways, calcium signaling, Rho GTPases, and protein kinase A signaling were also observed.

Conclusions

As behavioral, developmental, and genomic alterations are similar to those reported in ASD, these results lend support to prenatal exposure to VPA as a useful tool for understanding how developmental insults to molecular pathways in the amygdala give rise to ASD-related syndromes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-017-0160-x) contains supplementary material, which is available to authorized users.

Beyond infection - Maternal immune activation by environmental factors, microglial development, and relevance for autism spectrum disorders

Immune molecules such as cytokines and chemokines and the cells that produce them within the brain, notably microglia, are critical for normal brain development. This recognition has in recent years led to the working hypothesis that inflammatory events during pregnancy, e.g. in response to infection, may disrupt the normal expression of immune molecules during critical stages of neural development and thereby contribute to the risk for neurodevelopmental disorders such as autism spectrum disorder (ASD). This hypothesis has in large part been shepherded by the work of Dr. Paul Patterson and colleagues, which has elegantly demonstrated that a single viral infection or injection of a viral mimetic to pregnant mice significantly and persistently impacts offspring immune and nervous system function, changes that underlie ASD-like behavioral dysfunction including social and communication deficits. Subsequent studies by many labs - in humans and in non-human animal models - have supported the hypothesis that ongoing disrupted immune molecule expression and/or neuroinflammation contributes to at least a significant subset of ASD. The heterogeneous clinical and biological phenotypes observed in ASD strongly suggest that in genetically susceptible individuals, environmental risk factors combine or synergize to create a tipping or threshold point for dysfunction. Importantly, animal studies showing a link between maternal immune activation (MIA) and ASD-like outcomes in offspring involve different species and diverse environmental factors associated with ASD in humans, beyond infection, including toxin exposures, maternal stress, and maternal obesity, all of which impact inflammatory or immune pathways. The goal of this review is to highlight the broader implications of Dr. Patterson's work for the field of autism, with a focus on the impact that MIA by diverse environmental factors has on fetal brain development, immune system development, and the pathophysiology of ASD.

Endocannabinod Signal Dysregulation in Autism Spectrum Disorders: A Correlation Link between Inflammatory State and Neuro-Immune Alterations

Several studies highlight a key involvement of endocannabinoid (EC) system in autism pathophysiology. The EC system is a complex network of lipid signaling pathways comprised of arachidonic acid-derived compounds (anandamide, AEA) and 2-arachidonoyl glycerol (2-AG), their G-protein-coupled receptors (cannabinoid receptors CB1 and CB2) and the associated enzymes. In addition to autism, the EC system is also involved in several other psychiatric disorders (i.e., anxiety, major depression, bipolar disorder and schizophrenia). This system is a key regulator of metabolic and cellular pathways involved in autism, such as food intake, energy metabolism and immune system control. Early studies in autism animal models have demonstrated alterations in the brain's EC system. Autism is also characterized by immune system dysregulation. This alteration includes differential monocyte and macrophage responses, and abnormal cytokine and T cell levels. EC system dysfunction in a monocyte and macrophagic cellular model of autism has been demonstrated by showing that the mRNA and protein for CB2 receptor and EC enzymes were significantly dysregulated, further indicating the involvement of the EC system in autism-associated immunological disruptions. Taken together, these new findings offer a novel perspective in autism research and indicate that the EC system could represent a novel target option for autism pharmacotherapy.

Long-term altered immune responses following fetal priming in a non-human primate model of maternal immune activation

Infection during pregnancy can lead to activation of the maternal immune system and has been associated with an increased risk of having an offspring later diagnosed with a neurodevelopmental disorders (NDD) such as autism spectrum disorder (ASD) or schizophrenia (SZ). Most maternal immune activation (MIA) studies to date have been in rodents and usually involve the use of lipopolysaccharide (LPS) or polyinosinic:polycytidylic acid (poly I:C). However, since NDD are based on behavioral changes, a model of MIA in non-human primates could potentially provide data that helps illuminate complex behavioral and immune outputs in human NDD. In this study twenty-one pregnant rhesus macaques were either given three injections over 72 hours of poly I:C-LC, a double stranded RNA analog (viral mimic), or saline as a control. Injections were given near the end of the first trimester or near the end of the second trimester to determine if there were differences in immune output due to the timing of MIA.An additional three non-treated animals were used as controls. The offspring were followed until 4 years of age, with blood collected at the end of their first (year 1) and fourth (year 4) years to assess dynamic cellular immune function. Induced responses from peripheral immune cells were measured using multiplex assays.At one year of age, MIA exposed offspring displayed elevated production of innate inflammatory cytokines including: interleukin (IL)-1β, IL-6, IL-12p40, and tumor necrosis factor (TNF)α at baseline and following stimulation. At four years of age, the MIA exposed offspring continued to display elevated IL-1β, and there was also a pattern of an increased production of T-cell helper type (T_H)-2 cytokines, IL-4 and IL-13. Throughout this time period, the offspring of MIA treated dams exhibited altered behavioral phenotypes including increased stereotyped behaviors. During the first two years, stereotyped behaviors were associated with innate cytokine production. Self-directed behaviors were associated with T_H2 cytokine production at year 4. Data from this study suggests long-term behavioral and immune activation was present in offspring following MIA. This novel non-human primate model of MIA may provide a relevant clinically translational model to help further elucidate the role between immune dysfunction and complex behavioral outputs following MIA.

Increase of cytosolic phospholipase A2 as hydrolytic enzyme of phospholipids and autism cognitive, social and sensory dysfunction severity

BACKGROUND

Autism is neurodevelopmental disorder that is characterized by developmental, behavioral, social and sensory abnormalities. Researchers have focused in last years in immunological alteration and inflammation as a hot subject in autism field. This work aims to study the alteration in phospholipids (PE, PS, and PC) together with the change in cPLA2 concentration as the main phospholipid hydrolytic enzyme in autistic patients compared to control. It was also extended to find a correlation between these biomarkers and severity of autism measured as childhood autism rating scale (CARS), Social responsiveness scale (SRS), and Short sensory profile (SSP).

METHODS

Phospholipids (PE, PS, PC) and cPLA2 as biochemical parameters were determined in the plasma of 48 Saudi autistic male patients, categorized as mild-moderate and severe as indicated by their Childhood Autism Rating Scale (CARS), social responsiveness scale (SRS) and short sensory profile (SSP) and compared to 40 age- and gender-matched control samples.

RESULTS

The reported data demonstrate significantly lower levels of PE, PS, and PC together with a significant increase in cPLA2. While association between severity of autism and impaired phospholipid concentration was completely lacked, an association between cPLA2 and impaired sensory processing was observed.

CONCLUSIONS

The impaired phospholipid level and remarkable increased in cPLA2 concentration asserted their roles in the etiology of autism. Receiver operating characteristic analysis together with predictiveness diagrams proved that the measured parameters could be used as predictive biomarkers of clinical symptoms and provide significant guidance for future therapeutic strategy to re-establish physiological homeostasis.

Dynamic Akt/mTOR Signaling in Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a behaviorally defined disorder affecting 1 in 68 children. Currently, there is no known cause for the majority of ASD cases nor are there physiological diagnostic tools or biomarkers to aid behavioral diagnosis. Whole-genome linkage studies, genome-wide association studies, copy number variation screening, and SNP analyses have identified several ASD candidate genes, but which vary greatly among individuals and family clusters, suggesting that a variety of genetic mutations may result in a common pathology or alter a common mechanistic pathway. The Akt/mammalian target of rapamycin (mTOR) pathway is involved in many cellular processes including synaptic plasticity and immune function that can alter neurodevelopment. In this study, we examined the activity of the Akt/mTOR pathway in cells isolated from children with ASD and typically developing controls. We observed higher activity of mTOR, extracellular receptor kinase, and p70S6 kinase and lower activity of glycogen synthase kinase 3 (GSK3)α and tuberin (TSC2) in cells from children with ASD. These data suggest a phosphorylation pattern indicative of higher activity in the Akt/mTOR pathway in children with general/idiopathic ASD and may suggest a common pathological pathway of interest for ASD.

Immune Endophenotypes in Children With Autism Spectrum Disorder

BACKGROUND

Autism spectrum disorder (ASD) is characterized by social communication deficits and restricted, repetitive patterns of behavior. Varied immunological findings have been reported in children with ASD. To address the question of heterogeneity in immune responses, we sought to examine the diversity of immune profiles within a representative cohort of boys with ASD.

METHODS

Peripheral blood mononuclear cells from male children with ASD (n = 50) and from typically developing age-matched male control subjects (n = 16) were stimulated with either lipopolysaccharide or phytohemagglutinin. Cytokine production was assessed after stimulation. The ASD study population was clustered into subgroups based on immune responses and assessed for behavioral outcomes.

RESULTS

Children with ASD who had a proinflammatory profile based on lipopolysaccharide stimulation were more developmentally impaired as assessed by the Mullen Scales of Early Learning. They also had greater impairments in social affect as measured by the Autism Diagnostic Observation Schedule. These children also displayed more frequent sleep disturbances and episodes of aggression. Similarly, children with ASD and a more activated T cell cytokine profile after phytohemagglutinin stimulation were more developmentally impaired as measured by the Mullen Scales of Early Learning.

CONCLUSIONS

Children with ASD may be phenotypically characterized based upon their immune profile. Those showing either an innate proinflammatory response or increased T cell activation/skewing display a more impaired behavioral profile than children with noninflamed or non-T cell activated immune profiles. These data suggest that there may be several possible immune subphenotypes within the ASD population that correlate with more severe behavioral impairments.

Neonatal Cytokine Profiles Associated With Autism Spectrum Disorder

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that can be reliably diagnosed at age 24 months. Immunological phenomena, including skewed cytokine production, have been observed among children with ASD. Little is known about whether immune dysregulation is present before diagnosis of ASD.

METHODS

We examined neonatal blood spots from 214 children with ASD (141 severe, 73 mild/moderate), 62 children with typical development, and 27 children with developmental delay as control subjects who participated in the Childhood Autism Risks from Genetics and the Environment study, a population-based case-control study. Levels of 17 cytokines and chemokines were compared across groups and in relation to developmental and behavioral domains.

RESULTS

Interleukin (IL)-1β and IL-4 were independently associated with ASD compared with typical development, although these relationships varied by ASD symptom intensity. Elevated IL-4 was associated with increased odds of severe ASD (odds ratio [OR] = 1.40, 95% confidence interval [CI], 1.03, 1.91), whereas IL-1β was associated with increased odds of mild/moderate ASD (OR = 3.02, 95% CI, 1.43, 6.38). Additionally, IL-4 was associated with a higher likelihood of severe ASD versus mild/moderate ASD (OR = 1.35, 95% CI, 1.04, 1.75). In male subjects with ASD, IL-4 was negatively associated with nonverbal cognitive ability (β = -3.63, SE = 1.33, p = .04).

CONCLUSIONS

This study is part of a growing effort to identify early biological markers for ASD. We demonstrate that peripheral cytokine profiles at birth are associated with ASD later in childhood and that cytokine profiles vary depending on ASD severity. Cytokines have complex roles in neurodevelopment, and dysregulated levels may be indicative of genetic differences and environmental exposures or their interactions that relate to ASD.

Toll-like receptor 4 signaling is associated with upregulated NADPH oxidase expression in peripheral T cells of children with autism

Autism spectrum disorders (ASD) affect millions of children worldwide, and are characterized by impairment in social interaction and communication, and specific repetitive behavioral patterns. Growing evidence highlights a role of toll-like receptors (TLRs) in the pathogenesis of ASD. Specifically, TLR-4 activation has been shown to be associated with increased pro-inflammatory cytokines as well as autistic symptoms in offspring. NADPH oxidase (NOX-2) derived reactive oxygen species (ROS) have also been shown to play pathogenic role under inflammatory conditions. However, the role of TLR-4 in the regulation of NOX-2 derived ROS has not been explored in ASD, particularly in T cells. Therefore, this study explored TLR-4 and NOX-2 related signaling in peripheral T cells of ASD patients (n=35) and age-matched typically developing children (n=30). In this study, we find that ASD individuals have increased TLR-4 expression on T cells which is associated with increased NOX-2 expression and ROS generation as compared to typically developing children. Moreover, activation of TLR-4 on T cells by lipopolysaccharide (LPS) in vitro leads to enhanced generation of NOX-2 derived ROS via nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) pathway. These data support a link between T cell TLR-4 activation and NOX-2/ROS upregulation in ASD patients. Our study has implications in the context of neuroinflammation observed in ASD patients as ROS may lead to amplification and perpetuation of inflammation both in the periphery and central nervous system. Our data also suggest that therapeutic targeting of TLR-4 signaling may lead to reduction in inflammation of ASD patients.

Environmental factors influencing the risk of autism

Autism is a developmental disability with age of onset in childhood (under 3 years old), which is characterized by definite impairments in social interactions, abnormalities in speech, and stereotyped pattern of behaviors. Due to the progress of autism in recent decades, a wide range of studies have been done to identify the etiological factors of autism. It has been found that genetic and environmental factors are both involved in autism pathogenesis. Hence, in this review article, a set of environmental factors involved in the occurrence of autism has been collected, and finally, some practical recommendations for reduction of the risk of this devastating disease in children are represented.

The Role of the Immune System in Autism Spectrum Disorder

Autism is a neurodevelopmental disorder characterized by deficits in communication and social skills as well as repetitive and stereotypical behaviors. While much effort has focused on the identification of genes associated with autism, research emerging within the past two decades suggests that immune dysfunction is a viable risk factor contributing to the neurodevelopmental deficits observed in autism spectrum disorders (ASD). Further, it is the heterogeneity within this disorder that has brought to light much of the current thinking regarding the subphenotypes within ASD and how the immune system is associated with these distinctions. This review will focus on the two main axes of immune involvement in ASD, namely dysfunction in the prenatal and postnatal periods. During gestation, prenatal insults including maternal infection and subsequent immunological activation may increase the risk of autism in the child. Similarly, the presence of maternally derived anti-brain autoantibodies found in ~20% of mothers whose children are at risk for developing autism has defined an additional subphenotype of ASD. The postnatal environment, on the other hand, is characterized by related but distinct profiles of immune dysregulation, inflammation, and endogenous autoantibodies that all persist within the affected individual. Further definition of the role of immune dysregulation in ASD thus necessitates a deeper understanding of the interaction between both maternal and child immune systems, and the role they have in diagnosis and treatment.

C57BL/6J bone marrow transplant increases sociability in BTBR T+ Itpr3tf/J mice

Associative studies across a range of neurodevelopmental disorders have revealed a relationship between immune system function and behavioral deficits. These correlations are particularly evident in individuals with autism spectrum disorders (ASD), a developmental disorder characterized by social behavior deficits and noted for its high instances of immune system dysfunction. Mouse models provide a unique opportunity to explore causal links between immune and nervous system function and reveal how changes in these systems alter behavioral profiles. The BTBR T⁺ Itpr3^tf/J (BTBR) mouse strain is characterized by both social behavior impairments and aberrant immune responses, affording the unique opportunity to investigate the causal relationship between behavior and immunity through direct manipulation of these systems. Using bone marrow from the highly social C57BL/6J (C57) mouse strain, BTBR mice were tested for changes in social approach behavior and repetitive grooming following irradiation and bone marrow transplant. BTBR recipient mice treated with allogeneic bone marrow from C57 donor mice, but not syngeneic BTBR bone marrow, displayed increased sociability as measured by the three-chamber social approach task and total time spent social sniffing. In addition, C57 recipient mice given allogeneic bone marrow from BTBR donors showed a significant increase in repetitive grooming behavior. These data provide evidence for a causal relationship between peripheral immune phenotype and social behavior in the BTBR mouse strain and further strengthen and expand on our existing understanding of the role of immune function in behavior.

Peripheral Inflammatory Markers Contributing to Comorbidities in Autism

This study evaluates the contribution of peripheral biomarkers to comorbidities and clinical findings in autism. Seventeen autistic children and age-matched typically developing (AMTD), between three to nine years old were evaluated. The diagnostic followed the Diagnostic and Statistical Manual of Mental Disorders 4th Edition (DMS-IV) and the Childhood Autism Rating Scale (CARS) was applied to classify the severity. Cytokine profile was evaluated in plasma using a sandwich type ELISA. Paraclinical events included electroencephalography (EEG) record. Statistical analysis was done to explore significant differences in cytokine profile between autism and AMTD groups and respect clinical and paraclinical parameters. Significant differences were found to IL-1β, IL-6, IL-17, IL-12p40, and IL-12p70 cytokines in individuals with autism compared with AMTD (p < 0.05). All autistic patients showed interictalepileptiform activity at EEG, however, only 37.5% suffered epilepsy. There was not a regional focalization of the abnormalities that were detectable with EEG in autistic patients with history of epilepsy. A higher IL-6 level was observed in patients without history of epilepsy with interictalepileptiform activity in the frontal brain region, p < 0.05. In conclusion, peripheral inflammatory markers might be useful as potential biomarkers to predict comorbidities in autism as well as reinforce and aid informed decision-making related to EEG findings in children with Autism spectrum disorders (ASD).

Integrative analysis of genetic data sets reveals a shared innate immune component in autism spectrum disorder and its co-morbidities

BACKGROUND

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder that tends to co-occur with other diseases, including asthma, inflammatory bowel disease, infections, cerebral palsy, dilated cardiomyopathy, muscular dystrophy, and schizophrenia. However, the molecular basis of this co-occurrence, and whether it is due to a shared component that influences both pathophysiology and environmental triggering of illness, has not been elucidated. To address this, we deploy a three-tiered transcriptomic meta-analysis that functions at the gene, pathway, and disease levels across ASD and its co-morbidities.

RESULTS

Our analysis reveals a novel shared innate immune component between ASD and all but three of its co-morbidities that were examined. In particular, we find that the Toll-like receptor signaling and the chemokine signaling pathways, which are key pathways in the innate immune response, have the highest shared statistical significance. Moreover, the disease genes that overlap these two innate immunity pathways can be used to classify the cases of ASD and its co-morbidities vs. controls with at least 70 % accuracy.

CONCLUSIONS

This finding suggests that a neuropsychiatric condition and the majority of its non-brain-related co-morbidities share a dysregulated signal that serves as not only a common genetic basis for the diseases but also as a link to environmental triggers. It also raises the possibility that treatment and/or prophylaxis used for disorders of innate immunity may be successfully used for ASD patients with immune-related phenotypes.

Multiple inflammasome complexes are activated in autistic spectrum disorders

BACKGROUND

Inflammasomes are multimeric protein platforms involved in the regulation of inflammatory responses whose activity results in the production of proinflammatory cytokines. Because neuroinflammation is observed in autistic spectrum disorders (ASD), a neurologic condition of childhood resulting in a complex behavioural impairment, we analyzed the inflammasomes activity in ASD. Additionally we verified whether alterations of the gastrointestinal (GI) barriers might play a role in inflammasomes activation.

METHODS

The activity of the inflammasomes, the concentration of the inflammasomes-derived proinflammatory cytokines interleukin (IL)-1β and IL-18, and serum parameters of GI damage were analyzed in 25 ASD children, 23 healthy siblings (HS) and 30 unrelated age-matched healthy controls (HC).

RESULTS

A significant upregulation of the AIM2 and the NLRP3 inflammasomes and an increased production of IL-1β and IL-18 that was associated with a consistent reduction of IL-33, an anti inflammation cytokine were observed in ASD alone. Notably, in a possible immune-mediated attempt to dampen inflammation, IL-37, a suppressor of innate inflammatory responses, was significantly augmented in these same children. Finally, intestinal fatty acid binding protein (IFABP), an index of altered GI permeability, was significantly increased in serum of ASD and HS.

CONCLUSIONS

These results show that the inflammasomes are activated in ASD and shed light on the molecular mechanisms responsible for ASD-associated neuroinflammation. The observation that GI alterations could be present as well in ASD offers a possible link between such alterations and neuroinflammation. Therapeutic strategies targeting inflammasome activation could be useful in ASD.

Characterization of immune cell phenotypes in adults with autism spectrum disorders

Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by impairments in verbal and non-verbal communication, impaired social interactions and repetitive behaviors. There is evidence of a link between ASD symptoms and immune dysfunction, but few studies have been performed in adult patients to confirm this. In this work, we used flow cytometry to study immunological differences in peripheral blood mononuclear cells from 59 adult patients and 26 healthy control subjects to identify possible immune cell profiles related with this group of disorders. We analyzed six immune cell subpopulations (ie, B-cells, CD4(+) and CD8(+) T-cells, NK, NKT cells, and monocytes) and their corresponding stages of apoptosis and activation. The most noteworthy results showed that, compared to healthy controls, patients had increased percentages of CD8(+) T-cells and B-cells, and a decrease in the percentage of NKT cells. Regarding CD25 expression, we found overall CD25(+) overexpression, primarily in NK and NKT cells. Apoptosis percentage showed an increasing trend only in monocytes of patients. These data support a link between ASD and immune dysfunction, suggesting that specific cellular phenotypes and/or activation status of immune cells may be relevant in adult ASD.

Acetaminophen Use for Fever in Children Associated with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and restrictive behavior, interests, and activities. Our previous case-control study showed that use of acetaminophen at age 12-18 months is associated with increased likelihood for ASD (OR 8.37, 95% CI 2.08-33.7). In this study, we again show that acetaminophen use is associated with ASD (p = 0.013). Because these children are older than in our first study, the association is reversed; fewer children with ASD vs. non-ASD children use acetaminophen as a "first choice" compared to "never use" (OR 0.165, 95% CI 0.045, 0.599). We found significantly more children with ASD vs. non- ASD children change to the use of ibuprofen when acetaminophen is not effective at reducing fever (p = 0.033) and theorize this change in use is due to endocannabinoid system dysfunction. We also found that children with ASD vs. non-ASD children are significantly more likely to show an increase in sociability when they have a fever (p = 0.037) and theorize that this increase is due to anandamide activation of the endocannabinoid system in ASD children with low endocannabinoid tone from early acetaminophen use. In light of this we recommend that acetaminophen use be reviewed for safety in children.

Expression Profiling of LPS Responsive miRNA in Primary Human Macrophages

microRNAs (miRNAs) have emerged as important regulators of the innate and adaptive immune response. The purpose of the present study was to interrogate miRNA profiles of primary human macrophages challenged with bacterial lipopolysaccharide (LPS) with focus on expression kinetics. We employed Nanostring platform to precisely characterize the changes in miRNA expression following different doses and durations of LPS exposure. Differentially expressed miRNAs were identified in response to LPS challenge with convergent and divergent expression profiles. Pathway analysis of LPS-responsive miRNAs revealed regulation of biological processes linked to key cell signaling (including PIK3-Akt, MAP kinase, ErbB) and pathogen response pathways. Our data provide a comprehensive miRNA profiling of human primary macrophages treated with LPS. These results show that bacterial Toll like receptor (TLR) ligands can temporally modulate macrophage miRNA expression.

Innate immune receptor Toll-like receptor 4 signalling in neuropsychiatric diseases

The innate immunity is a stereotyped first line of defense against pathogens and unspecified damage signals. One of main actors of innate immunity are the Toll-like receptors (TLRs), and one of the better characterized members of this family is TLR-4, that it is mainly activated by Gram-negative bacteria lipopolysaccharide. In brain, TLR-4 organizes innate immune responses against infections or cellular damage, but also possesses other physiological functions. In the last years, some evidences suggest a role of TLR-4 in stress and stress-related neuropsychiatric diseases. Peripheral and brain TLR-4 activation triggers sickness behavior, and its expression is a risk factor of depression. Some elements of the TLR-4 signaling pathway are up-regulated in peripheral samples and brain post-mortem tissue from depressed and suicidal patients. The "leaky gut" hypothesis of neuropsychiatric diseases is based on the existence of an increase of the intestinal permeability which results in bacterial translocation able to activate TLR-4. Enhanced peripheral TLR-4 expression/activity has been described in subjects diagnosed with schizophrenia, bipolar disorder and in autistic children. A role for TLR-4 in drugs abuse has been also proposed. The therapeutic potential of pharmacological/genetic modulation of TLRs signaling pathways in neuropsychiatry is promising, but a great preclinical/clinical scientific effort is still needed.

A Non-inflammatory Role for Microglia in Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction, difficulties with language, and repetitive/restricted behaviors. The etiology of ASD is still largely unclear, but immune dysfunction and abnormalities in synaptogenesis have repeatedly been implicated as contributing to the disease phenotype. However, an understanding of how and if these two processes are related has not firmly been established. As non-inflammatory roles of microglia become increasingly recognized as critical to normal neurodevelopment, it is important to consider how dysfunction in these processes might explain the seemingly disparate findings of immune dysfunction and aberrant synaptogenesis seen in ASD. In this review, we highlight research demonstrating the importance of microglia to the development of normal neural networks, review recent studies demonstrating abnormal microglia in autism, and discuss how the relationship between these processes may contribute to the development of autism and other neurodevelopmental disorders at the cellular level.

From molecules to neural morphology: understanding neuroinflammation in autism spectrum condition

Growing evidence points toward a critical role for early (prenatal) atypical neurodevelopmental processes in the aetiology of autism spectrum condition (ASC). One such process that could impact early neural development is inflammation. We review the evidence for atypical expression of molecular markers in the amniotic fluid, serum, cerebrospinal fluid (CSF), and the brain parenchyma that suggest a role for inflammation in the emergence of ASC. This is complemented with a number of neuroimaging and neuropathological studies describing microglial activation. Implications for treatment are discussed.

Risk factors in autism: Thinking outside the brain

Autism spectrum disorders (ASD) are complex neurodevelopmental conditions that have been rising markedly in prevalence for the past 30 years, now thought to affect 1 in 68 in the United States. This has prompted the search for possible explanations, and has even resulted in some controversy regarding the "true" prevalence of autism. ASD are influenced by a variety of genetic, environmental, and possibly immunological factors that act during critical periods to alter key developmental processes. This can affect multiple systems and manifests as the social and behavioral deficits that define these disorders. The interaction of environmental exposures in the context of an individual's genetic susceptibilities manifests differently in each case, leading to heterogeneous phenotypes and varied comorbid symptoms within the disorder. This has also made it very difficult to elucidate underlying genes and exposure profiles, but progress is being made in this area. Some pharmaceutical drugs, toxicants, and metabolic and nutritional factors have been identified in epidemiological studies as increasing autism risk, especially during the prenatal period. Immunologic risk factors, including maternal infection during pregnancy, autoantibodies to fetal brain proteins, and familial autoimmune disease, have consistently been observed across multiple studies, as have immune abnormalities in individuals with ASD. Mechanistic research using animal models and patient-derived stem cells will help researchers to understand the complex etiology of these neurodevelopmental disorders, which will lead to more effective therapies and preventative strategies. Proposed therapies that need more investigation include special diets, probiotics, immune modulation, oxytocin, and personalized pharmacogenomic targets. The ongoing search for biomarkers and better treatments will result in earlier identification of ASD and provide much needed help and relief for afflicted families.

Adaptive and Innate Immune Responses in Autism: Rationale for Therapeutic Use of Intravenous Immunoglobulin

Background

Autism is a complex polygenic neurodevelopmental disorder characterized by deficits in communication and social interactions as well as specific stereotypical behaviors. Both genetic and environmental factors appear to contribute to the pathogenesis of autism. Accumulating data including changes in immune responses, linkage to major histocompatibility complex antigens, and the presence of autoantibodies to neural tissues/antigens suggest that the immune system plays an important role in its pathogenesis.

Summary

In this brief review, we discuss the data regarding changes in both innate and adaptive immunity in autism and the evidence in favor of the role of the immune system, especially of maternal autoantibodies in the pathogenesis of a subset of patients with autism. The rationale for possible therapeutic use of intravenous immunoglobulin is also discussed.

Decreased Phosphorylated Protein Kinase B (Akt) in Individuals with Autism Associated with High Epidermal Growth Factor Receptor (EGFR) and Low Gamma-Aminobutyric Acid (GABA)

Dysregulation of the PI3K/AKT/mammalian target of rapamycin (mTOR) pathway could contribute to the pathogenesis of autism spectrum disorders. In this study, phosphorylated Akt concentration was measured in 37 autistic children and 12, gender and age similar neurotypical, controls using an enzyme-linked immunosorbent assay. Akt levels were compared to biomarkers known to be associated with epidermal growth factor receptor (EGFR) and c-Met (hepatocyte growth factor (HGF) receptor) pathways and severity levels of 19 autism-related symptoms. We found phosphorylated Akt levels significantly lower in autistic children and low Akt levels correlated with high EGFR and HGF and low gamma-aminobutyric acid, but not other biomarkers. Low Akt levels also correlated significantly with increased severity of receptive language, conversational language, hypotonia, rocking and pacing, and stimming, These results suggest a relationship between decreased phosphorylated Akt and selected symptom severity in autistic children and support the suggestion that the AKT pathways may be associated with the etiology of autism.

Immune mediators in the brain and peripheral tissues in autism spectrum disorder

Increasing evidence points to a central role for immune dysregulation in autism spectrum disorder (ASD). Several ASD risk genes encode components of the immune system and many maternal immune system-related risk factors--including autoimmunity, infection and fetal reactive antibodies--are associated with ASD. In addition, there is evidence of ongoing immune dysregulation in individuals with ASD and in animal models of this disorder. Recently, several molecular signalling pathways--including pathways downstream of cytokines, the receptor MET, major histocompatibility complex class I molecules, microglia and complement factors--have been identified that link immune activation to ASD phenotypes. Together, these findings indicate that the immune system is a point of convergence for multiple ASD-related genetic and environmental risk factors.

The Impact of Neuroimmune Alterations in Autism Spectrum Disorder

Autism spectrum disorder (ASD) involves a complex interplay of both genetic and environmental risk factors, with immune alterations and synaptic connection deficiency in early life. In the past decade, studies of ASD have substantially increased, in both humans and animal models. Immunological imbalance (including autoimmunity) has been proposed as a major etiological component in ASD, taking into account increased levels of pro-inflammatory cytokines observed in postmortem brain from patients, as well as autoantibody production. Also, epidemiological studies have established a correlation of ASD with family history of autoimmune diseases; associations with major histocompatibility complex haplotypes and abnormal levels of immunological markers in the blood. Moreover, the use of animal models to study ASD is providing increasing information on the relationship between the immune system and the pathophysiology of ASD. Herein, we will discuss the accumulating literature for ASD, giving special attention to the relevant aspects of factors that may be related to the neuroimmune interface in the development of ASD, including changes in neuroplasticity.

Inflammation impairs social cognitive processing: A randomized controlled trial of endotoxin

Neuropsychiatric disorders (e.g., autism, schizophrenia) are partially characterized by social cognitive deficits, including impairments in the ability to perceive others' emotional states, which is an aspect of social cognition known as theory of mind (ToM). There is also evidence that inflammation may be implicated in the etiology of these disorders, but experimental data linking inflammation to deficits in social cognition is sparse. Thus, we examined whether exposure to an experimental inflammatory challenge led to changes in ToM. One hundred and fifteen (n=115) healthy participants were randomly assigned to receive either endotoxin, which is an inflammatory challenge, or placebo. Participants completed a social cognition task, the Reading the Mind in the Eyes (RME) test, at baseline and at the peak of the inflammatory response for the endotoxin group. The RME test, a validated measure of ToM, evaluates how accurately participants can identify the emotional state of another person by looking only at their eyes. We found that endotoxin (vs. placebo) led to decreases in performance on the RME test from baseline to the peak of inflammatory response, indicating that acute inflammation can lead to decreases in the ability to accurately and reliably comprehend emotional information from others. Given that deficits in ToM are implicated in neuropsychiatric disorders, including those which may have an inflammatory basis, these results may have implications for understanding the links between inflammation, social cognition, and neuropsychiatric disorders.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT01671150.

Reconfigurable microfluidic device with integrated antibody arrays for capture, multiplexed stimulation, and cytokine profiling of human monocytes

Monocytes represent a class of immune cells that play a key role in the innate and adaptive immune response against infections. One mechanism employed by monocytes for sensing foreign antigens is via toll-like receptors (TLRs)-transmembrane proteins that distinguish classes of foreign pathogens, for example, bacteria (TLR4, 5, and 9) vs. fungi (TLR2) vs. viruses (TLR3, 7, and 8). Binding of antigens activates a signaling cascade through TLR receptors that culminate in secretion of inflammatory cytokines. Detection of these cytokines can provide valuable clinical data for drug developers and disease investigations, but this usually requires a large sample volume and can be technically inefficient with traditional techniques such as flow cytometry, enzyme-linked immunosorbent assay, or luminex. This paper describes an approach whereby antibody arrays for capturing cells and secreted cytokines are encapsulated within a microfluidic device that can be reconfigured to operate in serial or parallel mode. In serial mode, the device represents one long channel that may be perfused with a small volume of minimally processed blood. Once monocytes are captured onto antibody spots imprinted into the floor of the device, the straight channel is reconfigured to form nine individually perfusable chambers. To prove this concept, the microfluidic platform was used to capture monocytes from minimally processed human blood in serial mode and then to stimulate monocytes with different TLR agonists in parallel mode. Three cytokines, tumor necrosis factor-α, interleukin (IL)-6, and IL-10, were detected using anti-cytokine antibody arrays integrated into each of the six chambers. We foresee further use of this device in applications such as pediatric immunology or drug/vaccine testing where it is important to balance small sample volume with the need for high information content.

Serotonin mediated immunoregulation and neural functions: Complicity in the aetiology of autism spectrum disorders

Serotonergic system has long been implicated in the aetiology of autism spectrum disorders (ASD), since platelet hyperserotonemia is consistently observed in a subset of autistic patients, who respond well to selective serotonin reuptake inhibitors. Apart from being a neurotransmitter, serotonin functions as a neurotrophic factor directing brain development and as an immunoregulator modulating immune responses. Serotonin transporter (SERT) regulates serotonin level in lymphoid tissues to ensure its proper functioning in innate and adaptive responses. Immunological molecules such as cytokines in turn regulate the transcription and activity of SERT. Dysregulation of serotonergic system could trigger signalling cascades that affect normal neural-immune interactions culminating in neurodevelopmental and neural connectivity defects precipitating behavioural abnormalities, or the disease phenotypes. Therefore, we suggest that a better understanding of the cross talk between serotonergic genes, immune systems and serotonergic neurotransmission will open wider avenues to develop pharmacological leads for addressing the core ASD behavioural deficits.

A model for the induction of autism in the ecosystem of the human body: the anatomy of a modern pandemic?

Background

The field of autism research is currently divided based on a fundamental question regarding the nature of autism: Some are convinced that autism is a pandemic of modern culture, with environmental factors at the roots. Others are convinced that the disease is not pandemic in nature, but rather that it has been with humanity for millennia, with its biological and neurological underpinnings just now being understood.

Objective

In this review, two lines of reasoning are examined which suggest that autism is indeed a pandemic of modern culture. First, given the widely appreciated derailment of immune function by modern culture, evidence that autism is strongly associated with aberrant immune function is examined. Second, evidence is reviewed indicating that autism is associated with ‘triggers’ that are, for the most part, a construct of modern culture. In light of this reasoning, current epidemiological evidence regarding the incidence of autism, including the role of changing awareness and diagnostic criteria, is examined. Finally, the potential role of the microbial flora (the microbiome) in the pathogenesis of autism is discussed, with the view that the microbial flora is a subset of the life associated with the human body, and that the entire human biome, including both the microbial flora and the fauna, has been radically destabilized by modern culture.

Conclusions

It is suggested that the unequivocal way to resolve the debate regarding the pandemic nature of autism is to perform an experiment: monitor the prevalence of autism after normalizing immune function in a Western population using readily available approaches that address the well-known factors underlying the immune dysfunction in that population.

Developmental neurotoxicity - challenges in the 21st century and in vitro opportunities

In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test- based guidelines are prohibitively expensive, at $ 1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies.

Inflammatory profiles in the BTBR mouse: how relevant are they to autism spectrum disorders?

Autism spectrum disorders (ASD) are a group of disorders characterized by core behavioral features including stereotyped interests, repetitive behaviors and impairments in communication and social interaction. In addition, widespread changes in the immune systems of individuals with ASD have been identified, in particular increased evidence of inflammation in the periphery and central nervous system. While the etiology of these disorders remains unclear, it appears that multiple gene and environmental factors are involved. The need for animal models paralleling the behavioral and immunological features of ASD is paramount to better understand the link between immune system dysregulation and behavioral deficits observed in these disorders. As such, the asocial BTBR mouse strain displays both ASD relevant behaviors and persistent immune dysregulation, providing a model system that has and continues to be instructive in understanding the complex nature of ASD.

Inflammatory Activity in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a severe neurodevelopmental disorder in early childhood characterized by impairment in communication and behavior. Recent research is focused on the immune dysregulation as a potential pathomechanism leading to ASD. Thus, we addressed the hypothesis that inflammatory activity might be enhanced in children suffering from ASD. We examined 15 children with ASD (13 boys/2 girls, mean age of 9.3 ± 0.7 years) and 20 age/gender-matched healthy subjects as a control group. All children were medication free and in good health. Hematological parameters in venous blood and plasma levels of pro-inflammatory cytokines - tumor necrosis factor alpha (TNF-α), interleukin 1ß (IL-1ß), and interleukin 8 (IL-8) - were assessed in each subject using human ultra-sensitive ELISA kits. In addition, TBARS as a marker of oxidative stress was evaluated. We found that the level of IL-8 was significantly increased in the ASD children, whereas the other markers remained unappreciably changed compared to controls (p = 0.003). In conclusion, the study demonstrates a discrete immune dysfunction in ASD of pro-inflammatory character.

Association between toll-like receptors expression and major depressive disorder

Accumulating evidences suggest that Toll-like receptors (TLRs) were involved in the pathophysiology of major depressive disorder. TLR4 was thought to be associated with major depressive disorder in animal model, but the others were still unknown. In order to examine TLR1-9 mRNA expression levels in peripheral blood and their relationships with the psychopathology of major depressive disorder, 30 patients with major depressive disorder were compared with 29 healthy controls. The 17-item Hamilton Depression Rating Scale (HAMD-17) was used to assess the severity of major depression. The mRNA expression levels of TLRs were examined in parallel with a housekeeping gene using real-time polymerase chain reaction (RT-PCR). Analysis of covariance with age and body mass index adjustment revealed a significantly higher expression of TLR3, 4, 5 and 7 mRNA but lower expression of TLR1 and 6 in patients with major depressive disorder as compared with healthy controls. Multiple linear regression analysis revealed that TLR4 was an independent risk factor relating to severity of major depression. These findings suggest that TLRs, especially TLR4, may be involved in the psychopathology of major depression.

Change in plasma cytokine levels during risperidone treatment in children with autism

BACKGROUND

Atypical antipsychotics decrease irritability in autism. They also affect the cytokine network. Psychological stress, depression, and, possibly, autism spectrum disorder (ASD) are associated with the production of pro-inflammatory cytokines. We sought to determine if risperidone treatment led to changes in plasma cytokine levels.

METHODS

Forty-five subjects from an open-label study of risperidone treatment of children and adolescents with ASD, ages 4-18 years, had an analysis of 27 different cytokines at baseline and after 8 weeks of treatment using multiplex assays (Millipore) and read on the Luminex 100(™) platform. We examined changes in each of the cytokine levels in the entire group, and also compared changes in cytokines in responders versus nonresponders.

RESULTS

After 8 weeks of risperidone treatment, 2 of the 27 plasma cytokines showed statistically significant decreases in median levels: Eotaxin (p=0.0003) and monocyte chemoattractant protein-1 (MCP-1) (p=0.0024). Six of the 48 subjects met two criteria for responders to risperidone, and the median values of interleukin (IL)-5 were significantly higher (p=0.005) in the overall responder group than in nonresponders.

CONCLUSIONS

Two cytokines, eotaxin and MCP-1, which have previously been identified as abnormally elevated in children with autism, decreased during treatment with risperidone. This suggests a possible mechanism of action of risperidone treatment and a balancing of the immune system in affected subjects in this very preliminary study.

Evidence supporting an altered immune response in ASD

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by deficits in social interactions, communication, and increased stereotypical repetitive behaviors. The immune system plays an important role in neurodevelopment, regulating neuronal proliferation, synapse formation and plasticity, as well as removing apoptotic neurons. Immune dysfunction in ASD has been repeatedly described by many research groups across the globe. Symptoms of immune dysfunction in ASD include neuroinflammation, presence of autoantibodies, increased T cell responses, and enhanced innate NK cell and monocyte immune responses. Moreover these responses are frequently associated with more impairment in core ASD features including impaired social interactions, repetitive behaviors and communication. In mouse models replacing immune components in animals that exhibit autistic relevant features leads to improvement in behavior in these animals. Taken together this research suggests that the immune dysfunction often seen in ASD directly affects aspects of neurodevelopment and neurological processes leading to changes in behavior. Discussion of immune abnormalities in ASD will be the focus of this review.

Cytokine profiles by peripheral blood monocytes are associated with changes in behavioral symptoms following immune insults in a subset of ASD subjects: an inflammatory subtype?

BACKGROUND

Some children with autism spectrum disorders (ASD) are characterized by fluctuating behavioral symptoms following immune insults, persistent gastrointestinal (GI) symptoms, and a lack of response to the first-line intervention measures. These children have been categorized as the ASD-inflammatory subtype (ASD-IS) for this study. We reported a high prevalence of non-IgE mediated food allergy (NFA) in young ASD children before, but not all ASD/NFA children reveal such clinical features of ASD-IS. This study addressed whether behavioral changes of ASD-IS are associated with innate immune abnormalities manifested in isolated peripheral blood (PB) monocytes (Mo), major innate immune cells in the PB.

METHODS

This study includes three groups of ASD subjects (ASD-IS subjects (N = 24), ASD controls with a history of NFA (ASD/NFA (N = 20), and ASD/non-NFA controls (N = 20)) and three groups of non-ASD controls (non-ASD/NFA subjects (N = 16), those diagnosed with pediatric acute onset-neuropsychiatric syndrome (PANS, N = 18), and normal controls without NFA or PANS (N = 16)). Functions of purified PB Mo were assessed by measuring the production of inflammatory and counter-regulatory cytokines with or without stimuli of innate immunity (lipopolysaccharide (LPS), zymosan, CL097, and candida heat extracts as a source of β-lactam). In ASD-IS and PANS subjects, these assays were done in the state of behavioral exacerbation ('flare') and in the stable ('non-flare') condition. ASD-IS children in the 'flare' state revealed worsening irritability, lethargy and hyperactivity.

RESULTS

'Flare' ASD-IS PB Mo produced higher amounts of inflammatory cytokines (IL-1β and IL-6) without stimuli than 'non-flare' ASD-IS cells. With zymosan, 'flare' ASD-IS cells produced more IL-1β than most control cells, despite spontaneous production of large amounts of IL-1ß. Moreover, 'flare' ASD-IS Mo produced less IL-10, a counterregulatory cytokine, in response to stimuli than 'non-flare' cells or other control cells. These changes were not observed in PANS cells.

CONCLUSIONS

We observed an imbalance in the production of inflammatory (IL-1ß and IL-6) and counterregulatory (IL-10) cytokines by 'flare' ASD-IS monocytes, which may indicate an association between intrinsic abnormalities of PB Mo and changes in behavioral symptoms in the ASD-IS subjects.

Increased Epidermal Growth Factor Receptor (EGFR) Associated with Hepatocyte Growth Factor (HGF) and Symptom Severity in Children with Autism Spectrum Disorders (ASDs)

BACKGROUND

One in 88 children in the US is thought to have one of the autism spectrum disorders (ASDs). ASDs are characterized by social impairments and communication problems. Growth factors and their receptors may play a role in the etiology of ASDs. Research has shown that epidermal growth factor receptor (EGFR) activation is associated with nerve cell development and repair. This study was designed to measure plasma levels of EGFR in autistic children and correlate these levels with its ligand, epidermal growth factor, other related putative biomarkers such as hepatocyte growth factor (HGF), the ligand for MET (MNNG HOS transforming gene) receptor, as well as the symptom severity of 19 different behavioral symptoms.

SUBJECTS AND METHODS

Plasma EGFR concentration was measured in 33 autistic children and 34 age- and gender-similar neurotypical controls, using an enzyme-linked immunosorbent assay. Plasma EGFR levels were compared to putative biomarkers known to be associated with EGFR and MET and severity levels of 19 autism-related symptoms.

RESULTS

We found plasma EGFR levels significantly higher in autistic children, when compared to neurotypical controls. EGFR levels correlated with HGF and high-mobility group protein B1 (HMGB1) levels, but not other tested putative biomarkers, and EGFR levels correlated significantly with severity of expressive language, conversational language, focus/attention, hyperactivity, eye contact, and sound sensitivity deficiencies.

CONCLUSIONS

These results suggest a relationship between increased plasma EGFR levels and designated symptom severity in autistic children. A strong correlation between plasma EGFR and HGF and HMGB1 suggests that increased EGFR levels may be associated with the HGF/Met signaling pathway, as well as inflammation.

High-mobility group box 1 (HMGB1) in childhood: from bench to bedside

High-mobility group box protein 1 (HMGB1) is a nonhistone nuclear protein that has a dual function. Inside the cell, HMGB1 binds DNA, regulating transcription and determining chromosomal architecture. Outside the cell, HMGB1 activates the innate system and mediates a wide range of physiological and pathological responses. HMGB1 exerts these actions through differential engagement of multiple surface receptors, including Toll-like receptor (TLR)2, TLR4, and receptor for advanced glycation end products (RAGE). HMGB1 is implicated as a late mediator of sepsis and is also involved in inflammatory and autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, HMGB1 was associated with tumor progression, becoming a potential therapeutic target, due to its involvement in the resistance to chemotherapy. Its implication on the pathogenesis of systemic vasculitis and inflammatory bowel diseases has also been evaluated. Moreover, it regulates neuroinflammation after traumatic brain injuries or cerebral infectious diseases. The aim of this review is to analyze these different roles of HMGB1, both in physiological and pathological conditions, discussing clinical and scientific implications in the field of pediatrics.

CONCLUSION

HMGB1 plays a key role in several pediatric diseases, opening new scenarios for diagnostic biomarkers and therapeutic strategies development.

Maternal immune activation leads to activated inflammatory macrophages in offspring

Several epidemiological studies have shown an association between infection or inflammation during pregnancy and increased risk of autism in the child. In addition, animal models have illustrated that maternal inflammation during gestation can cause autism-relevant behaviors in the offspring; so called maternal immune activation (MIA) models. More recently, permanent changes in T cell cytokine responses were reported in children with autism and in offspring of MIA mice; however, the cytokine responses of other immune cell populations have not been thoroughly investigated in these MIA models. Similar to changes in T cell function, we hypothesized that following MIA, offspring will have long-term changes in macrophage function. To test this theory, we utilized the poly (I:C) MIA mouse model in C57BL/6J mice and examined macrophage cytokine production in adult offspring. Pregnant dams were given either a single injection of 20mg/kg polyinosinic-polycytidylic acid, poly (I:C), or saline delivered intraperitoneally on gestational day 12.5. When offspring of poly (I:C) treated dams reached 10weeks of age, femurs were collected and bone marrow-derived macrophages were generated. Cytokine production was measured in bone marrow-derived macrophages incubated for 24h in either growth media alone, LPS, IL-4/LPS, or IFN-γ/LPS. Following stimulation with LPS alone, or the combination of IFN-γ/LPS, macrophages from offspring of poly (I:C) treated dams produced higher levels of IL-12(p40) (p<0.04) suggesting an increased M1 polarization. In addition, even without the presence of a polarizing cytokine or LPS stimulus, macrophages from offspring of poly (I:C) treated dams exhibited a higher production of CCL3 (p=0.05). Moreover, CCL3 levels were further increased when stimulated with LPS, or polarized with either IL-4/LPS or IFN-γ/LPS (p<0.05) suggesting a general increase in production of this chemokine. Collectively, these data suggest that MIA can produce lasting changes in macrophage function that are sustained into adulthood.

Immune dysregulation as a cause of autoinflammation in fragile X premutation carriers: link between FMRI CGG repeat number and decreased cytokine responses

Background

Increased rates of autoinflammatory and autoimmune disorders have been observed in female premutation carriers of CGG repeat expansion alleles of between 55–200 repeats in the fragile X mental retardation 1 (FMR1) gene. To determine whether an abnormal immune profile was present at a cellular level that may predispose female carriers to autoinflammatory conditions, we investigated dynamic cytokine production following stimulation of blood cells. In addition, splenocyte responses were examined in an FMR1 CGG knock-in mouse model of the fragile X premutation.

Methods

Human monocyte and peripheral blood leukocytes (PBLs) were isolated from the blood of 36 female FMR1 premutation carriers and 15 age-matched controls. Cells were cultured with media alone, LPS or PHA. In the animal model, splenocytes were isolated from 32 CGG knock-in mice and 32 wild type littermates. Splenocytes were cultured with media alone or LPS or PMA/Ionomycin. Concentrations of cytokines (GM-CSF, IL-1β, IL-6, IL-10, IL-13, IL-17, IFNγ, TNFα, and MCP-1) were determined from the supernatants of cellular cultures via Luminex multiplex assay. Additionally, phenotypic cellular markers were assessed on cells isolated from human subjects via flow cytometry.

Results

We found decreases in cytokine production in human premutation carriers as well as in the FMR1 knock-in mice when compared with controls. Levels of cytokines were found to be associated with CGG repeat length in both human and mouse. Furthermore, T cells from human premutation carriers showed decreases in cell surface markers of activation when compared with controls.

Conclusions

In this study, FMR1 CGG repeat expansions are associated with decreased immune responses and immune dysregulation in both humans and mice. Deficits in immune responses in female premutation carriers may lead to increased susceptibility to autoimmunity and further research is warranted to determine the link between FMR1 CGG repeat lengths and onset of autoinflammatory conditions.