Neuroinflammatory Gene Expression Alterations in Anterior Cingulate Cortical White and Gray Matter of Males With Autism Spectrum Disorder

Evidence for putative pathophysiological mechanisms of autism spectrum disorder (ASD), including peripheral inflammation, blood–brain barrier disruption, white matter alterations, and abnormal synaptic overgrowth, indicate a possible involvement of neuroinflammation in the disorder. Neuroinflammation plays a role in the development and maintenance of the dendritic spines involved in glutamatergic and GABAergic neurotransmission, and also influences blood–brain permeability. Cytokines released from microglia can impact the length, location or organization of dendritic spines on excitatory and inhibitory cells as well as recruit and impact glial cell function around the neurons. In this study, gene expression levels of anti- and pro-inflammatory signaling molecules, as well as oligodendrocyte and astrocyte marker proteins, were measured in both gray and white matter tissue in the anterior cingulate cortex from ASD and age-matched typically developing (TD) control brain donors, ranging from ages 4 to 37 years. Expression levels of the pro-inflammatory gene, HLA-DR, were significantly reduced in gray matter and expression levels of the anti-inflammatory gene MRC1 were significantly elevated in white matter from ASD donors as compared to TD donors, but neither retained statistical significance after correction for multiple comparisons. Modest trends toward differences in expression levels were also observed for the pro-inflammatory (CD68, IL1β) and anti-inflammatory genes (IGF1, IGF1R) comparing ASD donors to TD donors. The direction of gene expression changes comparing ASD to TD donors did not reveal consistent findings implicating an elevated pro- or anti-inflammatory state in ASD. However, altered expression of pro- and anti-inflammatory gene expression indicates some involvement of neuroinflammation in ASD. Lay Summary: The anterior cingulate cortex is an integral brain region in modulating social behaviors including nonverbal communication. The study found that inflammatory gene expression levels were altered in this brain region. We hypothesize that the inflammatory changes in this area could impact neuronal function. The finding has future implications in using these molecular markers to identify potential environmental exposures and distinct cell differences in autism

Vitamin D receptor gene expression in human and mouse cingulate cortex

Autism Spectrum Disorder (ASD) is characterized by a variety of social, sensory, and developmental symptoms. It is estimated that there are 66 cases per 10,000 children in the United States, placing the U.S. in the top ten countries with the highest prevalence of autism. Japan currently has the highest rate at 161 cases per 10,000. There is currently no known cure for this developmental disorder and the diagnostic protocol is not very clear. Those diagnosed are likely to face years of therapy and exposure to different medications to treat the symptoms. However, one risk factor that has received more attention in recent studies is that of Vitamin D and its relationship with ASD. It has been shown that environmental factors can lead to gene expression changes that may affect social behaviors, a core deficit of ASD. Vitamin D deficiencies during development can lead to the upregulation of DNA-repair genes and maternal deficiencies during pregnancy which may inhibit gene repair in the developing fetus. Deficits in Vitamin D have been linked to an increase in the autoimmune response of the body and are thought to lower the immune system’s attack on infections. Quantitative PCR was used to evaluate vitamin D receptor expression in human and mouse homogenate brain tissue punches from the cingulate cortex to determine Vitamin D receptor expression levels. Associations between Vitamin D and ASD may bring us one step closer to determining whether a simple addition of Vitamin D during the prenatal period could help decrease the risk of a developmental disorder such as autism

Laser Capture Microdissection Analysis of Inflammatory-Related Alterations in Postmortem Brain Tissue of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a social, sensory and developmental condition that affects one in 59 children and specifically one in 42 boys. Despite the 15% increase in prevalence in the last two years, there is no specific etiology, objective diagnostic criteria, or drug treatment. However, up-regulation of inflammation in ASD patients has been demonstrated in blood samples. Increased peripheral inflammation could have devastating effects on the developing brain. Peripheral inflammation in the blood could cross the blood-brain-barrier to stimulate microglia in the brain to produce aberrant levels of cytokines that regulate neuroinflammation such as insulin-like growth factor one (IGF1) that could alter neuronal cell-surface expression and neurotransmission. Additionally, arginase serves as a marker of inflammation, produced and expressed during cellular remodeling during brain injury. A balance of neurotransmitters, glutamate and gamma-aminobutyric acid (GABA), is critical to facilitate inter-regional signaling in the brain. Alterations of inflammatory molecules and the effects on glutamatergic neurons ability to uptake GABA in certain brain areas is currently unknown in ASD. Pathological changes in brain areas associated with social behaviors have been identified in postmortem tissue from ASD donors when compared to typically developing (TD) age and gender matched control tissue, as well as, in imaging scans of living individuals with ASD. We hypothesize that expression of inflammatory related molecules are increased in the identified brain areas related to symptoms of ASD and can be associated with altered gene expression changes in neurons as shown by gamma-aminobutyric acid type A receptor alpha 1 subunit (GABRA1). Dysfunction of GABRA1 on glutamatergic neurons could disrupt the typical neuronal balance of glutamate and GABA signaling. Inflammatory markers, IGF1 and insulin-like growth factor one receptor (IGF1R), were evaluated using quantitative polymerase chain reaction (QPCR). Additionally, IGF1 and arginase were evaluated using immunohistochemistry in both white and gray matter from the anterior cingulate cortex (ACC). Laser capture microdissection (LCM) was used to obtain single cell captures of glutamatergic neurons. IGF1R and GABRA1 gene expression was measured using end point PCR. A significant increase in IGF1 expression was obtained in the white matter punch in comparison to typically developed age-matched subjects using QPCR during initial statistical significance, however, was ultimately not significant. Additionally, IGF1R expression was significantly increased in ASD neurons in comparison to TD subjects utilizing the LCM method. However, a decrease expression in GABRA1 trended significance indicating a possible alteration in the neuron’s ability to facilitate proper signaling. These findings are the foundation of future investigations of signaling pathways in ASD that may uncover cell-specific etiologies and drug therapies for a condition that is only projected to increase in prevalence