Glial Cells

20 Papers / 3 Studies / Adjuvant / ASD Subtypes / Astrocytes / Cytokines / Detoxification / Endothelial Cells / Genes / Glial Cells / Glutathione / HLA / Immune / Inflammation / Males / Mercury / Mitochondria / Oxidative Stress / Sulfhydryl Groups / Thimerosal / Toxicants

The Putative Role of Environmental Mercury in the Pathogenesis and Pathophysiology of Autism Spectrum Disorders and Subtypes

Excerpt:
“Environmental mercury is neurotoxic at doses well below the current reference levels considered to be safe, with evidence of neurotoxicity in children exposed to environmental sources including fish consumption and ethylmercury-containing vaccines. Possible neurotoxic mechanisms of mercury include direct effects on sulfhydryl groups, pericytes and cerebral endothelial cells, accumulation within astrocytes, microglial activation, induction of chronic oxidative stress, activation of immune-inflammatory pathways and impairment of mitochondrial functioning. (Epi-)genetic factors which may increase susceptibility to the toxic effects of mercury in ASD include the following: a greater propensity of males to the long-term neurotoxic effects of postnatal exposure and genetic polymorphisms in glutathione transferases and other glutathione-related genes and in selenoproteins. Furthermore, immune and inflammatory responses to immunisations with mercury-containing adjuvants are strongly influenced by polymorphisms in the human leukocyte antigen (HLA) region and by genes encoding effector proteins such as cytokines and pattern recognition receptors. Some epidemiological studies investigating a possible relationship between high environmental exposure to methylmercury and impaired neurodevelopment have reported a positive dose-dependent effect.”

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  • July 22, 2017
Glial Cells / Males / Neurons / Toxicants

Gestational Exposure to Air Pollution Alters Cortical Volume, Microglial Morphology, and Microglia-Neuron Interactions in a Sex-Specific Manner

Excerpts:

“…several large scale epidemiological studies have recently linked prenatal air pollution exposure with an increased risk of neurodevelopmental disorders such as autism spectrum disorder (ASD).”

“We have demonstrated that prenatal exposure to DEP in mice, i.e., to the pregnant dams throughout gestation, results in a persistent vulnerability to behavioral deficits in adult offspring, especially in males, which is intriguing given the greater incidence of ASD in males to females (∼4:1).”

“DEP exposure increased inflammatory cytokine protein and altered the morphology of microglia, consistent with activation or a delay in maturation, only within the embryonic brains of male mice…”

“Consistent with this hypothesis, we found increased microglial-neuronal interactions in male offspring that received DEP compared to all other groups. Taken together, these data suggest a mechanism by which prenatal exposure to environmental toxins may affect microglial development and long-term function, and thereby contribute to the risk of neurodevelopmental disorders.”

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  • May 31, 2017
Glial Cells / Inflammation / Neuroinflammation / Oxidative Stress / Toxicants

Large Brains in Autism: The Challenge of Pervasive Abnormality

Excerpt: “Oxidative stress, brain inflammation, and microgliosis have been much documented in association with toxic exposures including various heavy metals…the awareness that the brain as well as medical conditions of children with autism may be conditioned by chronic biomedical abnormalities such as inflammation opens the possibility that meaningful biomedical interventions may be possible well past the window of maximal neuroplasticity in early childhood because the basis for assuming that all deficits can be attributed to fixed early developmental alterations in neural architecture has now been undermined.”

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  • June 29, 2016
Androgens / Excitotoxicity / Glial Cells / Glutamate / Homocysteine / Immune / Inflammation / Mercury / Metallothionein / Mitochondria / Neurons / Review / Thimerosal / Toxicants / Transsulfuration

A possible central mechanism in autism spectrum disorders, part 2: immunoexcitotoxicity

Abstract

In this section, I explore the effects of mercury and inflammation on transsulfuration reactions, which can lead to elevations in androgens, and how this might relate to the male preponderance of autism spectrum disorders (ASD). It is known that mercury interferes with these biochemical reactions and that chronically elevated androgen levels also enhance the neurodevelopmental effects of excitotoxins. Both androgens and glutamate alter neuronal and glial calcium oscillations, which are known to regulate cell migration, maturation, and final brain cytoarchitectural structure. Studies have also shown high levels of DHEA and low levels of DHEA-S in ASD, which can result from both mercury toxicity and chronic inflammation. Chronic microglial activation appears to be a hallmark of ASD. Peripheral immune stimulation, mercury, and elevated levels of androgens can all stimulate microglial activation. Linked to both transsulfuration problems and chronic mercury toxicity are elevations in homocysteine levels in ASD patients. Homocysteine and especially its metabolic products are powerful excitotoxins. Intimately linked to elevations in DHEA, excitotoxicity and mercury toxicity are abnormalities in mitochondrial function. A number of studies have shown that reduced energy production by mitochondria greatly enhances excitotoxicity. Finally, I discuss the effects of chronic inflammation and elevated mercury levels on glutathione and metallothionein.

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  • January 1, 2015
Genes / Glial Cells / Immune

Transcriptome analysis reveals dysregulation of innate immune response genes and neuronal activity-dependent genes in autism

Abstract

Recent studies of genomic variation associated with autism have suggested the existence of extreme heterogeneity. Large-scale transcriptomics should complement these results to identify core molecular pathways underlying autism. Here we report results from a large-scale RNA sequencing effort, utilizing region-matched autism and control brains to identify neuronal and microglial genes robustly dysregulated in autism cortical brain. Remarkably, we note that a gene expression module corresponding to M2-activation states in microglia is negatively correlated with a differentially expressed neuronal module, implicating dysregulated microglial responses in concert with altered neuronal activity-dependent genes in autism brains. These observations provide pathways and candidate genes that highlight the interplay between innate immunity and neuronal activity in the aetiology of autism.

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  • December 10, 2014
Adjuvant / Aluminum / Autoimmunity / Cytokines / Dendritic cells / Excitotoxicity / GI / Glial Cells / Glutamate / Immune / Mercury / Review / Thimerosal / TNF-α / Toxicants / Vaccine Schedule

A possible central mechanism in autism spectrum disorders, part 1

Abstract

The autism spectrum disorders (ASD) are a group of related neurodevelopmental disorders that have been increasing in incidence since the 1980s. Despite a considerable amount of data being collected from cases, a central mechanism has not been offered. A careful review of ASD cases discloses a number of events that adhere to an immunoexcitotoxic mechanism. This mechanism explains the link between excessive vaccination, use of aluminum and ethylmercury as vaccine adjuvants, food allergies, gut dysbiosis, and abnormal formation of the developing brain. It has now been shown that chronic microglial activation is present in autistic brains from age 5 years to age 44 years. A considerable amount of evidence, both experimental and clinical, indicates that repeated microglial activation can initiate priming of the microglia and that subsequent stimulation can produce an exaggerated microglial response that can be prolonged. It is also known that one phenotypic form of microglia activation can result in an outpouring of neurotoxic levels of the excitotoxins, glutamate and quinolinic acid. Studies have shown that careful control of brain glutamate levels is essential to brain pathway development and that excesses can result in arrest of neural migration, as well as dendritic and synaptic loss. It has also been shown that certain cytokines, such as TNF-alpha, can, via its receptor, interact with glutamate receptors to enhance the neurotoxic reaction. To describe this interaction I have coined the term immunoexcitotoxicity, which is described in this article.

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  • November 1, 2014
Aluminum / Autism Biomarkers / Glial Cells / Inflammation / Lipids / Mercury / Mitochondria / Neuroinflammation / Oxidative Stress / Thimerosal / Toxicants

Biomarkers in Autism

Abstract

Autism spectrum disorders (ASDs) are complex, heterogeneous disorders caused by an interaction between genetic vulnerability and environmental factors. In an effort to better target the underlying roots of ASD for diagnosis and treatment, efforts to identify reliable biomarkers in genetics, neuroimaging, gene expression, and measures of the body’s metabolism are growing. For this article, we review the published studies of potential biomarkers in autism and conclude that while there is increasing promise of finding biomarkers that can help us target treatment, there are none with enough evidence to support routine clinical use unless medical illness is suspected. Promising biomarkers include those for mitochondrial function, oxidative stress, and immune function. Genetic clusters are also suggesting the potential for useful biomarkers.

Excerpt: “A recent review assessed the research on physiological abnormalities associated with ASD (44). The authors identified four main mechanisms that have been increasingly studied during the past decade: immunologic/inflammation, oxidative stress, environmental toxicants, and mitochondrial abnormalities. In addition, there is accumulating research on the lipid, GI systems, microglial activation, and the microbiome, and how these can also contribute to generating biomarkers associated with ASD (45, 46).

Pathways are interconnected with a defect in one likely leading to dysfunction in others. Many metabolic disorders can lead to endpoints such as impaired methylation, sulfuration, and detoxification pathways and nutritional deficiencies. Mitochondrial dysfunction, environmental risk factors, metabolic imbalances, and genetic susceptibility can all lead to oxidative stress (47), which in turn leads to inflammation, damaged cell membranes, autoimmunity (48), impaired methylation (49), cell death (48), and neurological deficits (50). The brain is highly vulnerable to oxidative stress (51), particularly in children (52) during the early part of development (47). As environmental events and metabolic imbalances affect oxidative stress and methylation, they also can affect the expression of genes.”

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  • August 12, 2014
Amygdala / Cytokines / Dendritic cells / GI / Glial Cells / Immune / Inflammation / Regression

Myeloid dendritic cells frequencies are increased in children with autism spectrum disorder and associated with amygdala volume and repetitive behaviors

Excerpt:
“Dendritic cells play key roles in modulating immune responses and differences in frequencies or functions of these cells may result in immune dysfunction in children with ASD. These data further implicate innate immune cells in the complex pathophysiology of ASD.”

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  • July 16, 2013
Autoimmunity / Cytokines / Glial Cells / Immune / Inflammation / Post-mortem / Pregnancy

Immunological and autoimmune considerations of Autism Spectrum Disorders

Excerpt:
“While the etiology of ASD remains unknown, various clues suggest a possible association with altered immune responses and ASD. Inflammation in the brain and CNS has been reported by several groups with notable microglia activation and increased cytokine production in postmortem brain specimens of young and old individuals with ASD.”

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  • July 15, 2013

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