Social stress exacerbations on acute Theiler's virus infection: a role for Interleukin-6

Neurodegenerative diseases, such as multiple sclerosis (MS), are adversely affected by both stress and inflammation. Theiler's murine encephalomyelitis virus infection is an excellent animal model of MS, allowing examination of central nervous system inflammation during the acute phase of infection. Social disruption stress exacerbates acute Theiler's virus infection. Both social disruption stress and Theiler's virus infection elevate the proinflammatory cytokine, Interleukin-6 (IL-6). The current study examined the necessity and sufficiency of IL-6 in mediating the negative effects of social disruption stress in acute Theiler's virus infection. Experiment 1 blocked IL-6 function with a neutralizing antibody administered simultaneously with social disruption stress. All mice were then infected, and measures of illness, motor impairment and physiological signs of disease were collected up to 21 d postinfection. Experiment 2 administered exogenous IL-6 for one week (replacing social disruption with the cytokine treatment), followed by infection. Measures identical to those collected in Experiment 1 were collected for up to 21 d postinfection. Results indicate that IL-6 is necessary for the development of the sickness, motor impairment, and immunological effects of social stress in acute Theiler's virus infection. In contrast, IL-6 alone can induce some, but not all, of the sickness behavior exacerbations, and was not sufficient for the development of either motor impairment or immunological effects previously associated with social disruption stress. These results have many important implications for further research in the effects of social stress on Theiler's virus infection, as well as clinical implications for both MS and other inflammatory mediated diseases, such as Alzheimer's disease and Parkinson's disease

The effect of stress on the neuropathogenesis of Theiler's virus-induced demyelination as an animal model of multiple sclerosis

Stressful life events have been associated with the onset and/or exacerbation of multiple sclerosis (MS). To investigate the effects of stress on the pathogenesis of MS, we employed restraint stress (RST) in the TheilerâÂÂs virus-induced demyelination (TVID) model, an animal model for human MS. Intracerebral inoculation of susceptible strain of mice with TheilerâÂÂs murine encephalomyelitis virus (TMEV) results in a biphasic disease â an acute encephalomyelitis and chronic demyelination. The establishment of persistent viral infection is critical in inducing immune-mediated demyelination during the chronic disease. The exposure of mice to RST prior to viral infection produced a stress response as evidenced by elevated circulating corticosterone (CORT). To further study the effect of stress on the immune response to TMEV infection and demyelination, we first examined the cytokine and chemokine response during the acute TMEV infection. We demonstrated that RST down-regulated the virus-induced expression of chemokines, Ltn, IP-10, RANTES, and pro-inflammatory cytokines, TNF, IFN and LT in both the brain and spleen during early infection. Histologically, a decreased pattern of inflammation was observed in the brain of restrained mice as compared to non-restrained mice. The increased viral titer was noted in the CNS of restrained mice and was correlated with the decreased production of pro-inflammatory cytokine, suggesting an impaired immune response by RST. Secondly, the duration of stress on the late demyelination was investigated. Repeated and chronically stressed SJL/J mice developed an early onset of clinical signs and a delayed onset was observed in acutely stressed mice. Both acute and chronic RST suppressed the antibody response to TMEV and stressed displayed a higher incidence of demyelination than non-restrained mice. Axonal loss was also noted in chronic stressed mice. Additionally, RST caused an increased systemic viral infection in extraneural organs during the acute infection and cardiotropic TMEV was isolated from the heart of stressed mice. Taken together, stress resulted in profound immunsuppression during acute infection, which may consequently increase the incidence of demyelination. The present study may be generalized in human MS which is potentially triggered by viral infection

The effects of neuroinflammation on the subventricular zone neurogenic compartment following Theiler's Murine Encephalomyelitis virus infection and its regulation by Galectin-3

The subventricular zone (SVZ) is an adult neurogenic niche that contains multipotent stem/progenitor cells that may be a viable target for remyelination in Multiple Sclerosis. In response to demyelination, SVZ progenitors are recruited into myelin lesions. Currently, the effect of inflammation on the endogenous brain stem cell compartment remains poorly characterised. Theiler's murine encephalomyelitis virus (TMEV) induces a demyelinating disease in susceptible SJL/J mice, due to persistence of the virus, which models the chronic progressive form of multiple sclerosis. In contrast, virus is rapidly cleared in TMEV resistant C57BL/6 mice. This viral clearance is critically dependent on infiltration of CD4+ and CD8+ T cells during the first 3-14 days after infection, through the blood vessels and meninges. This project aimed to characterise the impact of TMEV induced inflammation on SVZ homeostasis. In both strains of mice the most pronounced and consistent inflammation in the CNS was observed in periventricular regions and in particular, the SVZ, which showed targeted infection by the TMEV virus. However, the time course and kinetics for infiltration at 3,7 and 14 days post infection have very different profiles between resistant C57BL/6 and susceptible SJL mice. Using RT-PCR arrays and ELISA I have shown that these differences in T cell infiltration to the SVZ may be due to much higher chemokine and cytokine expression levels in B6 mice. TMEV infection decreases SVZ cell proliferation and results in a loss of neuroblast numbers. Galectin-3 (Gal-3) is a β-galactoside binding protein that is constitutively expressed specifically in the SVZ. Following TMEV infection Gal-3 levels are significantly upregulated in the SVZ, with higher expression in B6 mice compared to SJL mice. Primary SVZ astrocytes secrete extracellular Galectin-3 at much higher levels than cortical astrocytes. Galectin-3 is a pro-inflammatory mediator which upon secretion is able to activate immune and inflammatory signaling events and amplify pro-inflammatory cytokine production. Both SJL and B6 Gal-3-/- KO mice have decreased expression of CCL2, CCL5 CXCL10 and CCL8 chemokines in the SVZ after TMEV infection. Deletion of Gal-3 prevents the loss of SVZ proliferation and in B6 mice decreases hematopoietic cell infiltration and enhances ectopic neuroblast emigration. These data implicate Galectin- 3 as a novel regulator of the SVZ inflammatory response and may provide a new target for regulating T cell CNS immigration in autoimmune disease

The Impact of Social Stress on Central Nervous System Inflammation and T Cell Response to Theiler’s Virus Infection

A growing body of evidence suggests that social stress contributes to the pathogenesis of neurodegenerative diseases, such as multiple sclerosis (MS). For example, prior research has shown that social disruption (SDR) stress behaviorally and immunologically exacerbates Theiler’s murine encephalomyelitis virus (TMEV) infection. TMEV infection results in acute infection of the central nervous system (CNS) followed by a chronic demyelinating autoimmune disease, similar to that seen in MS. Research suggests that social stress exerts these effects by altering the immune response to infection. More specifically, it is hypothesized that SDR sensitizes the acute inflammatory response to infection and suppresses T cell effector function in the acute phase of disease. It was demonstrated that SDR is sufficient to alter inflammation. Exposure to a single session of SDR increases IL-­‐1β mRNA expression; however, IL-­‐6 mRNA expression, but not IL-­‐1β, is up regulated in response to chronic SDR. Furthermore, chronic SDR prior to infection resulted in increased infection related central IL-­‐6 and IL-­‐1β mRNA expression, and central administration of IL-­‐6 neutralizing antibody during SDR reverses this increase in neuroinflammation. This suggests that SDR sensitizes infection related CNS inflammation through an up-­‐regulation of IL-­‐6. Chronic SDR prior to infection also resulted in enhanced CNS viral titers and suppression of virus-­‐induced CD4 and CD8 T cell IFN-­‐γ release within the CNS. As a whole, this research indicates that SDR exacerbates the disease course of TMEV infection by altering the central innate and adaptive immune response to infection. This research enhances our understanding of the mechanisms by which social stress exacerbates neurodegenerative disease pathogenesis

DEVELOPING METHODS FOR ANTAGONIZING TNF-α AND IL-1β IN THE CENTRAL NERVOUS SYSTEM

Stressful life events have been linked to the onset, susceptibility, and even progression of neurodegenerative diseases such as multiple sclerosis (MS). Theiler’s murine encephalomyelitis virus (TMEV) infection, a well-characterized animal model of MS, is used in our laboratory to investigate the interaction between social stressors and disease development. Social disruption (SDR), a model of social stress used in our laboratory, appears to worsen Theiler’s virus infection through excessive inflammation. Prior findings from our laboratory indicate that pro-inflammatory cytokine IL-6 is partially mediating the negative effects of SDR in the development of Theiler’s virus infection. In order to examine the role of other pro-inflammatory cytokines, our objective was to develop techniques to block the cytokines TNF-α and IL-1β. Prior studies have indicated stress-induced release of these cytokines (TNF-α and IL-1β) may mediate the adverse effects of disease development in subsequent immune challenges. Balb/cJ mice were implanted with a permanent indwelling cannula in the left lateral ventricle of the brain and allowed to recover for one week prior to manipulations. Once the animals recovered from cannulation surgery, neutralizing antibody to TNF-α or IL-1β was administered during the period of SDR. Antibody-SDR treatments continued for one week. Mice were sacrificed the morning following last day of SDR. Brains and sera were collected to measure TNF-α or IL-1β levels. Spleens were harvested to examine the development of glucocorticoid resistance (GCR), a hallmark of SDR, in the TNF-α study only. The ELISA assay was not sensitive enough to the tissue levels of TNF-α, therefore successful antagonism was undetectable. In contrast, IL-1β was elevated during SDR; however, it appears that the antibody was only partially effective at the dose administered. The GCR assay indicated that resistance occurred in antibody treated and control mice in the TNF-α study, signifying that antibody treatment does not interfere with the development of normal social stress effects. Future studies are necessary to identify an effective blocking dose for the neutralizing antibody to IL-1β. In addition, we also need to develop alternative assays, such as RT-PCR or an RNase protection assay, that are sensitive to the levels of TNF-α associated with SDR.This research was supported by F31 NS504762 Fellowship to RRJ, NMSS RG3128 and NINDS RO1 NS39569to CJRW and MWM, and the Office of Honors and Academic Scholarships

Experimental Autoimmune Encephalomyelitis

Experimental Autoimmune Encephalomyelitis - Models, Disease Biology and Experimental Therapy is totally focused on the model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). The book chapters give a very good and in depth overview about the currently existing and most used EAE models. In addition, chapters dealing with novel experimental therapeutic approaches demonstrate the usefulness of the EAE model for MS research. With an international perspective, this book features contributions from authors throughout the world, Australia, Germany, Japan, Spain, Taiwan, and USA. There is an impressive international Faculty that provides insight into current research themes. This further demonstrates the importance of EAE in research all over the world. The book will provide established researchers and students with novel insights and guidance for their research and will help to push the field forward

The impact of social stress on acute Theiler's murine encephalitis virus infection.

Stress is known to alter immune function, both in positive and negative ways. The disparate effects of stress on immune function remains an active area of investigation. This thesis investigates how the application of social disruption stress either prior to or concurrent with infection alters the neuropathogenesis of Theiler's murine encephalitis virus. Experiment 1 verified that social disruption prior to infection exacerbated the course of infection. Experiment 2 examined application of social disruption concurrent with infection, and found that this may produce a delay in symptom onset, and possibly a protective effect. Experiment 3 directly compared the two schedules to each other. The previous findings were replicated and expanded with additional measures (both behavioral and physiological) that further verified the earlier findings. Social disruption applied prior to infection resulted in greater behavioral and physiological exacerbation of the disease. Concurrently applied stress remained protective or inhibitory in the disease progression. Timing of stress is one of several quantitative aspects of stress that has been found to impact the stress-immune interaction and should be further investigated

The effects of psychological stress on an animal model of multiple sclerosis, Theiler's virus induced demyelination

Multiple Sclerosis (MS) is the most common demyelinating condition of the central nervous system (CNS), resulting in paralysis and death. The etiology of MS is unknown. However, genetics, exposure to a pathogen, psychological stress and gender are all implicated in the onset and progression of the disease. An animal model of MS, Theilers virus (TMEV) infection, causes a biphasic disease. An early CNS viral infection, if allowed to persist within the CNS, is followed by a chronic CNS autoimmune demyelinating condition that is similar to MS. The development of Theilers Virus Induced Demyelination (TVID) is under genetic control: SJL mice are highly susceptible to viral persistence and TVID while CBA mice have an intermediate susceptibility. Chronic restraint stress (RST) administered during the first four weeks of TMEV infection influenced the subsequent development of TVID differentially across strain and sex of mice. TVID was exacerbated by RST in male and female SJL mice, but in the CBA strain, TVID was alleviated by RST in male mice only. This pattern of results in SJL and CBA mice could be seen in the chronic phase of TVID on multiple dependent measures: body weights, behavioral signs of the chronic phase, rotarod performance (an automated measure of motor abilities), and inflammation, demyelination, and axonal loss within the spinal cord. The exacerbation of TVID in SJL mice provides some of the first experimental evidence that coincides with reports of stress precipitating the onset of MS in human patients. The sex dependent alleviation of TVID in CBA mice illustrates the complex interaction between genetic predisposition, gender, stress, and exposure to a pathogen that has been proposed for the development of MS

The Effects of Chronic Restraint Stress on Innate and Adaptive Immune Responses to Acute Theiler?s Murine Encephalomyelitis Virus Infection ? An Animal Model of Human Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated prevalent chronic demyelinating and neurodegenerative disease of the central nervous system that begins with an abrupt onset during early adulthood. MS is idiopathic, but many factors are thought to influence the pathogenesis of the disease, which include genetic, gender and environmental factors. To date, there is much evidence that suggest that both the onset and progression of MS is facilitated by both viral infections and stress. Theiler’s murine encephalomyelitis virus (TMEV) is a picornavirus that upon inoculation into susceptible strains of mice (i.e. SJL and CBA) causes a persistent infection which, in turn, results in an early acute encephalomyelitis followed by a late chronic immune-mediated demyelinating and neurodegenerative disease that pathologically resembles MS. In contrast, resistant mice (i.e C57BL/6 and BALB/c) are able to clear the virus from the CNS, and consequently do not develop chronic demyelination. Previous studies indicated that stress during early infection of susceptible mice can increase CNS viral titers and alter dissemination of TMEV, decrease early cytokine and chemokine expression in the spleen and CNS, and result in an exacerbated late demyelinating disease. The studies herein, focused on the hypothesis that chronic stress during early infection with TMEV infection would lead to drastic immunosuppression of both innate and adaptive arms of immunity, and that this immunosuppression may overcome the genetically controlled resistance of C57BL/6 mice to Theiler’s virus-induced demyelination. In these series of studies, we were able to show that stress, regardless of mouse strain susceptibility, decreases NK cell activity, and increased viral titers at day 1 p.i. Furthermore, after seven days of stress, susceptible mice demonstrated decreased virus specific T-cell effector function in both the CNS and spleens as indicated by a globalized reduction in type 1 and type 2 cytokines, as well as transcription factors. Importantly, these decreased responses were, in part, attributable to the actions of glucocorticoids. However, stress during early infection of C57BL/6 mice did not alter resistance to demyelination. These results begin to shed light on how stress, infection, and genetics can influence the onset of human MS