Impaired immune function in Gulf War Illness

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>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.</p> <p>Results</p> <p>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 <it>in vitro </it>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.</p> <p>Conclusion</p> <p>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.</p

Predicting Health Impacts of the World Trade Center Disaster: 1. Halogenated hydrocarbons, symptom syndromes, secondary victimization, and the burdens of history

The recent attack on the World Trade Center, in addition to direct injury and psychological trauma, has exposed a vast population to dioxins, dibenzofurans, related endocrine disruptors, and a multitude of other physiologically active chemicals arising from the decomposition of the massive quantities of halogenated hydrocarbons and other plastics within the affected buildings. The impacts of these chemical species have been compounded by exposure to asbestos, fiberglass, crushed glass, concrete, plastic, and other irritating dusts. To address the manifold complexities of this incident we combine recent theoretical perspectives on immune, CNS, and sociocultural cognition with empirical studies on survivors of past large toxic fires, other community-scale chemical exposure incidents, and the aftereffects of war. Our analysis suggests the appearance of complex, but distinct and characteristic, spectra of synergistically linked social, psychosocial, psychological and physical symptoms among the 100,000 or so persons most directly affected by the WTC attack. The different 'eigenpatterns' should become increasingly comorbid as a function of exposure. The expected outcome greatly transcends a simple 'Post Traumatic Stress Disorder' model, and may resemble a particularly acute form of Gulf War Syndrome. We explore the role of external social factors in subsequent exacerbation of the syndrome -- secondary victimization -- and study the path-dependent influence of individual and community-level historical patterns of stress. We suggest that workplace and other organizations can act as ameliorating intermediaries. Those without acess to such buffering structures appear to face a particularly bleak future

Model-Based Therapeutic Correction of Hypothalamic-Pituitary-Adrenal Axis Dysfunction

The hypothalamic-pituitary-adrenal (HPA) axis is a major system maintaining body homeostasis by regulating the neuroendocrine and sympathetic nervous systems as well modulating immune function. Recent work has shown that the complex dynamics of this system accommodate several stable steady states, one of which corresponds to the hypocortisol state observed in patients with chronic fatigue syndrome (CFS). At present these dynamics are not formally considered in the development of treatment strategies. Here we use model-based predictive control (MPC) methodology to estimate robust treatment courses for displacing the HPA axis from an abnormal hypocortisol steady state back to a healthy cortisol level. This approach was applied to a recent model of HPA axis dynamics incorporating glucocorticoid receptor kinetics. A candidate treatment that displays robust properties in the face of significant biological variability and measurement uncertainty requires that cortisol be further suppressed for a short period until adrenocorticotropic hormone levels exceed 30% of baseline. Treatment may then be discontinued, and the HPA axis will naturally progress to a stable attractor defined by normal hormone levels. Suppression of biologically available cortisol may be achieved through the use of binding proteins such as CBG and certain metabolizing enzymes, thus offering possible avenues for deployment in a clinical setting. Treatment strategies can therefore be designed that maximally exploit system dynamics to provide a robust response to treatment and ensure a positive outcome over a wide range of conditions. Perhaps most importantly, a treatment course involving further reduction in cortisol, even transient, is quite counterintuitive and challenges the conventional strategy of supplementing cortisol levels, an approach based on steady-state reasoning

Translational Biomarker Research for Militarily Relevant Populations in Neurocognitive Diseases

In recent decades more soldiers are being mobilized to conflict areas, such as the over 2 million service members, who have been deployed to Iraq and Afghanistan since October 2001, which includes but is not limited to Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF); or the 700,000 service veterans deployed to the Persian Gulf War in 1990-91 in the US. The UK mobilized over 46,000 military personnel to Iraq, 9,500 British troops to Afghanistan and 50,000 troops to the Gulf War. Soldiers are being exposed to traumatic events such as physical and psychological trauma, as well as chemical exposure and therefore service members are at risk of postdeployment health-related issues, associated commonly with post-traumatic stress disorder (PTSD) and traumatic brain injury (TBI) among OEF/OIF veterans, as well as Gulf War Illness (GWI) among the Persian Gulf War Veteran population. Although progress has been made in identifying underlying pathology for TBI and PTSD and acute as well as sub-acute biomarkers have been identified, with commercially available tests on the horizon, the work presented here addresses a critical but underinvestigated issue, the need for chronic biomarkers for these conditions, as they can go undetected for an extended period of time. Additionally, more evidence has surfaced that discusses how symptoms related to mild TBI (mTBI) can last for years after the insult, emphasizing the importance of investigatjng biomarkers at a late timepoint after injury as, owing to the mild nature of the injury, the condition was often undiagnosed at the time. PTSD itself still lacks an objective measure that can capture its complexity, whereas co-morbidity of PTSD with TBI further complicates the issue. The other mentioned militarily relevant condition, termed GWI, faces similar issues. Veterans deployed to the Persian Gulf War in 1991 suffer from a disease that has shown to exhibit persistent multisymptom complexity. No biomarker has been identified for this particular population thus making objective diagnosis difficult. Besides the identification of clinical biomarkers, much research has been done in preclinical models, yet there is still a need to verify and validate such animal models in order to demonstrate their utility. Once the validity of a preclinical model has been confirmed, investigation of pathogenic mechanisms in those models has the potential to reveal therapeutic targets of relevance to the human condition. Chapter 1 will discuss epidemiology, current clinical diagnosis and pathophysiology of TBI, PTSD and GWI as well as the status of biomarker research in each of these three areas. The thesis then focuses on the identification of plasma biomarkers in human patient populations, specifically in military populations suffering from TBI, PTSD or both at chronic time points post traumatic exposure (Chapters 2 & 3). In Chapter 4, we then explore whether or not such changes are present in our established animal model of TBI. In Chapter 5 we investigate peripheral biomarkers in plasma samples from Gulf War veterans and in two animal models of GWI. Given the complexity of TBI, PTSD and GWI clinical presentation and pathogenesis and their heterogeneity in human populations, it is anticipated that a valid biomarker for broad application will in fact require assessment of many markers to create a panel that can support diagnosis. The lipidomic and proteomic analyses I employed in this work are approaches with the required breadth and lack of bias to be successful in such an undertaking, and I hope that the work described in this thesis provides a foundation for future development of such biomarker panels

Identification of Biomolecular Pathways Associated With the Central Nervous System Based Symptoms of Gulf War Illness

The clinical profile of GWI is characterized by the presence the central nervous systems (CNS) symptoms which include memory impairment, anxiety, widespread pain and motor problems. Now, even twenty years later, veterans with GWI continue to suffer from these persistent symptoms. Currently, there is no treatment available for treating GWI, which is largely due to the complexity of the clinical presentation of this illness and the heterogeneity of GW exposures. The main goals of this thesis were to develop and characterize GW agent exposure mouse models that recapitulate the CNS symptoms of GWI and to identify the underlying aberrant biological pathways. Three major objectives were undertaken to accomplish these goals: (1) Two mouse models of GW-agent exposure were developed using combination of the anti-nerve gas treatment pyridostigmine bromide (PB), pesticides (permethrin), an insect repellent (N,N-Diethyl-meta-toluamide) and stress. Neurobehavioral studies show that combined exposure to GW agents produced anxiety and sensorimotor deficits in one mouse model and anxiety and cognitive impairment in the other. Neuropathological studies showed a presence of astrogliosis in both models. (2) Exploratory proteomic studies suggested that lipid-metabolism and immune/inflammation were associated with GW-agent exposure. (3) As lipid dysfunction is upstream of the inflammatory pathways, a lipidomics approach was used to identify the GW-agent exposure dependent lipid profiles. Lipid profiles of mouse models of GW-agent exposure were compared with those of other neurological conditions to identify profiles that were unique to GW-agent exposure. Lipid profiles were interrogated to identify lipid-metabolism pathways that may be amenable to therapeutic targeting. Studies described in this thesis provide novel insight into the pathobiology of GWI and suggest that pathways involved in phosphatidylcholine metabolism might be of therapeutic value in treating the CNS symptoms of GWI

Covariates of corticotropin-releasing hormone (CRH) concentrations in cerebrospinal fluid (CSF) from healthy humans

BACKGROUND: Define covariates of cerebrospinal corticotropin-releasing hormone (CRH) levels in normal humans. CRH(CSF )was measured in 9 normal subjects as part of an intensive study of physiological responses stressors in chronic pain and fatigue states. CRH(CSF )was first correlated with demographic, vital sign, HPA axis, validated questionnaire domains, baseline and maximal responses to pain, exercise and other stressors. Significant factors were used for linear regression modeling. RESULTS: Highly significant correlations were found despite the small number of subjects. Three models were defined: (a) CRH(CSF )with blood glucose and sodium (explained variance = 0.979, adjusted R(2 )= 0.958, p = 0.02 by 2-tailed testing); (b) CRH(CSF )with resting respiratory and heart rates (R(2 )= 0.963, adjusted R(2 )= 0.939, p = 0.007); and (c) CRH(CSF )with SF-36 Vitality and Multidimensional Fatigue Inventory Physical Fatigue domains (R(2 )= 0.859, adjusted R(2 )= 0.789, p = 0.02). CONCLUSIONS: Low CRH(CSF )was predicted by lower glucose, respiratory and heart rates, and higher sodium and psychometric constructs of well being. Responses at peak exercise and to other acute stressors were not correlated. CRH(CSF )may have reflected an overall, or chronic, set-point for physiological responses, but did not predict the reserves available to respond to immediate stressors

Investigations of the conscious sensation of fatigue in patients with chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a debilitating disorder of unknown pathogenesis, characterised by fatigue which is not relieved by rest, accompanied by assorted symptoms including cognitive difficulties, pain, and unrefreshing sleep. One hallmark of the symptom complex in CFS is a transient exacerbation of the fatigue state after relatively minor physical activity or cognitive activity often termed a post-exertional exacerbation . By applying challenge paradigms, the studies presented in this thesis aimed to analyse the biological underpinnings of the disorder during periods of worsened fatigue and symptoms following the imposition of environmental challenges a physical exercise protocol and a simulated-driving protocol (representing a cognitively-demanding task). These paradigms allowed analysis of a working conceptual model that CFS is a result of central sensitisation , representing augmented responsiveness of the central nervous system (CNS) to signals either from the periphery or from within the brain - resulting in altered sensory processing within the brain and ultimately the excessive conscious sensation of fatigue. Across the two challenge studies, patients with CFS reported high levels of fatigue in their baseline state (consistent with the diagnostic criteria for the disorder). This was measured using a new fatigue scale specifically designed for these studies to allow real-time measurement of the phenomenon. In comparison to matched healthy participants, at baseline, the patients had impairments in cognitive function, longer night-time sleep, less day-time physical activity and movement, and less heart rate variability - an index of vagal activity, around the time of night-time sleep, but no alterations in gene expression for biomarkers previously linked with the sensation of fatigue, or in indices of interoception. These findings are generally consistent with previous evidence for autonomic nervous system and cognitive disturbances in patients with CFS. However, while both the physical and cognitive challenges induced an exacerbation of fatigue lasting hours-to-days in patients with CFS (with little or no change in healthy participants), there were no corresponding changes in gene expression, cognitive performance, indices of interoception, indices of vagal activity, or sleep and activity patterns. As such, the inability to detect meaningful changes in biological parameters indirectly reflecting central sensitisation post-challenge did not allow for confirmation or denial of the hypothesis that the post-exertional exacerbation of fatigue and related symptoms is due to central sensitisation . Further studies are warranted using these challenge protocols in conjunction with more direct measures of central sensitisation such as functional neuro-imaging

Norepinephrine mediates the effects of restraint stress on Theiler's Murine Encephalomyelitis Virus

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 13-15).Theiler's Murine Encephalomyelitis Virus (TMEV) is an important model of multiple sclerosis (MS) (Lipton, 1975). Theiler's virus induces a biphasic disease that, in the chronic phase, causes a remitting relapsing demyelination of the central nervous system (CNS) similar to that of MS. Chronic restraint stress in the acute/early phase profoundly affects vulnerability to TMEV. When an animal is subjected to a stressor, several biological pathways are activated. Previous studies conducted in our lab have investigated the role of the hypothalamic pituitary adrenal (HPA) axis and the glucocorticoid corticosterone. The sympathetic nervous system (SNS) is also activated by stress and initiates the release of the catecholamine norepinephrine (NE) from the adrenal medulla. Norepinephrine is believed to have immunosuppressive effects. Here, we attempt to determine if NE is mediating the deleterious effects restraint stress on TMEV. To examine this issue, seventy-one 24-day old male CBA mice were surgically implanted with either a pellet of the β₂-adrenergic antagonist nadolol, or a pellet containing only vehicle on three days prior to infection. The mice were then restrained for 12 hours overnight, and infected intracranially with 5 X10⁴ PFU of the BeAn strain of TMEV on day 0 post infection. For the following 4 weeks, restraint was administered 5 nights a week for 12 hours per session. The effects of stress on TMEV were measured daily using two scales, one to measure the relative sickness of the animal and the second to measure the degree of hind limb weakness and paralysis. The body weight of the animals was also recorded daily. This study confirms that norepinephrine is indeed a mediator of the stress response. Animals receiving the placebo had higher mortality, more severe clinical symptoms, and greater hind limb weakness and paralysis than animals receiving the norepinephrine antagonist nadolol