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Oligodendrocyte involvement in Gulf War Illness.

ABSTRACT: Low level sarin nerve gas and other anti-cholinesterase agents have been implicated in Gulf War illness (GWI), a chronic multi-symptom disorder characterized by cognitive, pain and fatigue symptoms that continues to afflict roughly 32% of veterans from the 1990-1991 Gulf War. How disrupting cholinergic synaptic transmission could produce chronic illness is unclear, but recent research indicates that acetylcholine also mediates communication between axons and oligodendrocytes. Here we investigated the hypothesis that oligodendrocyte development is disrupted by Gulf War agents, by experiments using the sarin-surrogate acetylcholinesterase inhibitor, diisopropyl fluorophosphate (DFP). The effects of corticosterone, which is used in some GWI animal models, were also investigated. The data show that DFP decreased both the number of mature and dividing oligodendrocytes in the rat prefrontal cortex (PFC), but differences were found between PFC and corpus callosum. The differences seen between the PFC and corpus callosum likely reflect the higher percentage of proliferating oligodendroglia in the adult PFC. In cell culture, DFP also decreased oligodendrocyte survival through a non-cholinergic mechanism. Corticosterone promoted maturation of oligodendrocytes, and when used in combination with DFP it had protective effects by increasing the pool of mature oligodendrocytes and decreasing proliferation. Cell culture studies indicate direct effects of both DFP and corticosterone on OPCs, and by comparison with in vivo results, we conclude that in addition to direct effects, systemic effects and interruption of neuron-glia interactions contribute to the detrimental effects of GW agents on oligodendrocytes. Our results demonstrate that oligodendrocytes are an important component of the pathophysiology of GWI.

SUBMITTER: Belgrad J

PROVIDER: S-EPMC6899710 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Oligodendrocyte involvement in Gulf War Illness.

Belgrad Jillian J Dutta Dipankar J DJ Bromley-Coolidge Samantha S Kelly Kimberly A KA Michalovicz Lindsay T LT Sullivan Kimberly A KA O'Callaghan James P JP Fields Richard Douglas RD

Glia 20190724 11

Low level sarin nerve gas and other anti-cholinesterase agents have been implicated in Gulf War illness (GWI), a chronic multi-symptom disorder characterized by cognitive, pain and fatigue symptoms that continues to afflict roughly 32% of veterans from the 1990-1991 Gulf War. How disrupting cholinergic synaptic transmission could produce chronic illness is unclear, but recent research indicates that acetylcholine also mediates communication between axons and oligodendrocytes. Here we investigate ...[more]

PMID: 31339622

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Project description:Gulf War Illness (GWI) is a complex condition that involves multiple organ systems and is characterized by an abrupt or delayed onset of persistent/relapsing symptomatology such as memory and other neurological problems, muscle and joint pain, gastrointestinal issues, hormonal imbalance, immune dysfunction and debilitating fatigue. Currently, treatment of the condition relies solely on management of symptomatology and improvement in quality of life due to a lack of knowledgeof the underlying mechanisms of disease onset and progression. An improved understanding of the key mechanisms of GWI and dysfunction within regulatory systems will lead to more objective diagnosis methods and adequate management of patients by providing targeted approaches to treatment. Disruption of DNA methylation patterns has been tied to various immune, neurological and endocrine disease states; however, the status of this epigenetic mark in GWI remains uncertain. This study aimed at identifying biomarkers of GWI by gaining knowledge on DNA methylation patterns of GWI in an effort to determine therapeutic targets of disease activity and provide insight into disease onset and progression. Methods: Genomic DNA from 10 GWI patients and 10 healthy controls [HC] (“experimental cohort”) prepared from PBMCs was analyzed with ELISA-based DNA methylation assays and Illumina MethylationEPIC microarrays. These arrays allow measuring the methylation status at 850,000 CpG sites. Methylation changes in promoter regions were separately analyzed and used as input data in ingenuity pathway analysis software to identify altered functional pathways. Relevant differentially methylated CpG sites (DMS) were validated by pyrosequencing. Results: Global DNA methylation levels using the ELISA-based assay on the DNA isolated from PBMCs of GWI patients were similar to those of HC. However, deeper evaluation using microarray-based genome-wide technology allowed detection of DMS in GWI patients with respect to HC. As an overall 10,767 CpG sites presented with differential DNA methylation levels across promoters, gene regulatory elements and within coding regions of genes. Majority of these DMS were hypermethylated in GWI patients as compared to the HC, and more than half of these sites localized to promoters and gene regulatory elements, relative to distribution of DMSin the network as a whole, indicating gene regulatory potential. Functional pathway analysis of the 776 genes with differentially methylated promoters (DMPs) fulfilling FDR≤0.2 criteriafollowing a genomic region-based approachlinks GWI to defects in at least 15 different pathways mostly related to cell signaling with a strong immune component. Conclusions: This is the first study that has explored genome-wide epigenetic changes associated with GWI using the new MethylationEPIC microarrays covering about 850,000 CpG sites; which builds on previous methylation preliminary reports. The data obtained are consistent with previous evidence for dysregulation of the immune system in GWI and suggests a role of this epigenetic modification on the DNA pathobiology of GWI. They are also consistent with previous reports showing a Th1- to Th2-mediated immune response shift in GWI in addition to altered immune system function. Future validation studies in larger cohorts of GWI patients and evaluation of the effects of these methylation patterns on gene expression regulation are granted.

Project description:BACKGROUND:Gulf War Illness (GWI) remains a serious health consequence for at least 11,000 veterans of the first Gulf War in the early 1990s. Our understanding of the health consequences that resulted remains inadequate, and this is of great concern with another deployment to the same theater of operations occurring now. Chronic immune cell dysfunction and activation have been demonstrated in patients with GWI, although the literature is not uniform. We exposed GWI patients and matched controls to an exercise challenge to explore differences in immune cell function measured by classic immune assays and gene expression profiling. METHODS:This pilot study enrolled 9 GWI cases identified from the Department of Veterans Affairs GWI registry, and 11 sedentary control veterans who had not been deployed to the Persian Gulf and were matched to cases by sex, body mass index (BMI) and age. We measured peripheral blood cell numbers, NK cytotoxicity, cytokines and expression levels of 20,000 genes immediately before, immediately after and 4 hours following a standard bicycle ergometer exercise challenge. RESULTS:A repeated-measures analysis of variance revealed statistically significant differences for three NK cell subsets and NK cytotoxicity between cases and controls (p < 0.05). Linear regression analysis correlating NK cell numbers to the gene expression profiles showed high correlation of genes associated with NK cell function, serving as a biologic validation of both the in vitro assays and the microarray platform. Intracellular perforin levels in NK and CD8 T-cells trended lower and showed a flatter profile in GWI cases than controls, as did the expression levels of the perforin gene PRF1. Genes distinguishing cases from controls were associated with the glucocorticoid signaling pathway. CONCLUSION:GWI patients demonstrated impaired immune function as demonstrated by decreased NK cytotoxicity and altered gene expression associated with NK cell function. Pro-inflammatory cytokines, T-cell ratios, and dysregulated mediators of the stress response (including salivary cortisol) were also altered in GWI cases compared to control subjects. An interesting and potentially important observation was that the exercise challenge augments these differences, with the most significant effects observed immediately after the stressor, possibly implicating some block in the NK and CD8 T-cells ability to respond to "stress-mediated activation". This has positive implications for the development of laboratory diagnostic tests for this syndrome and provides a paradigm for exploration of the immuno-physiological mechanisms that are operating in GWI, and similar complex syndromes. Our results do not necessarily elucidate the cause of GWI, but they do reveal a role for immune cell dysfunction in sustaining illness.

Project description:The Boston University-based Gulf War Illness Consortium (GWIC) is a multidisciplinary initiative developed to provide detailed understanding of brain and immune alterations that underlie Gulf War illness (GWI), the persistent multisymptom disorder associated with military service in the 1990-1991 Gulf War. The core GWIC case-control clinical study conducted in-depth brain and immune evaluation of 269 Gulf War veterans (223 GWI cases, 46 controls) at three U.S. sites that included clinical assessments, brain imaging, neuropsychological testing, and analyses of a broad range of immune and immunogenetic parameters. GWI cases were similar to controls on most demographic, military, and deployment characteristics although on average were two years younger, with a higher proportion of enlisted personnel vs. officers. Results of physical evaluation and routine clinical lab tests were largely normal, with few differences between GWI cases and healthy controls. However, veterans with GWI scored significantly worse than controls on standardized assessments of general health, pain, fatigue, and sleep quality and had higher rates of diagnosed conditions that included hypertension, respiratory and sinus conditions, gastrointestinal conditions, and current or lifetime depression and post-traumatic stress disorder. Among multiple deployment experiences/exposures reported by veterans, multivariable logistic regression identified just two significant GWI risk factors: extended use of skin pesticides in theater (adjusted OR = 3.25, p = 0.005) and experiencing mild traumatic brain injury during deployment (OR = 7.39, p = 0.009). Gulf War experiences associated with intense stress or trauma (e.g., participation in ground combat) were not associated with GWI. Data and samples from the GWIC project are now stored in a repository for use by GWI researchers. Future reports will present detailed findings on brain structure and function, immune function, and association of neuroimmune measures with characteristics of GWI and Gulf War service.

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Oligodendrocyte involvement in Gulf War Illness.

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Oligodendrocyte involvement in Gulf War Illness.

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