Differential effects of stress-induced adrenal function on components of the herpes simplex virus-specific memory cytotoxic T-lymphocyte response

Characterization of beta2-adrenergic receptor knockout mouse model during Chlamydia muridarum genital infection

Chlamydia genital infection caused by Chlamydia trachomatis is the most common bacterial sexually transmitted disease worldwide. A mouse model has been developed in our laboratory to better understand the effect of cold-induced stress on chlamydia genital infection and immune response. However, the stress mechanism affecting the host response to Chlamydia muridarum genital infection remains unclear. Here, we demonstrate a role for the beta2-adrenergic receptor (β2-AR), which binds noradrenaline and modulates the immune response against chlamydia genital infection in a mouse model. A successful β2-AR homozygous knockout (KO) mouse model was used to study the infection and analyze the immune response. Our data show that stressed mice lacking the β2-AR are less susceptible to C. muridarum genital infection than controls. A correlation was obtained between lower organ load and higher interferon-gamma production by CD4+ and CD8+ cells of the KO mice. Furthermore, exposure of CD4+ T cells to noradrenaline alters the production of cytokines in mice during C. muridarum genital infection. This study suggests that the blockade of β2-AR signaling could be used to increase resistance to chlamydia genital infection. We value the β2-AR KO as a viable model that can provide reproducible results in investigating medical research, including chlamydia genital infection.

Mucosal herpes immunity and immunopathology to ocular and genital herpes simplex virus infections

Herpes simplex viruses type 1 and type 2 (HSV-1 and HSV-2) are amongst the most common human infectious viral pathogens capable of causing serious clinical diseases at every stage of life, from fatal disseminated disease in newborns to cold sores genital ulcerations and blinding eye disease. Primary mucocutaneous infection with HSV-1 & HSV-2 is followed by a lifelong viral latency in the sensory ganglia. In the majority of cases, herpes infections are clinically asymptomatic. However, in symptomatic individuals, the latent HSV can spontaneously and frequently reactivate, reinfecting the muco-cutaneous surfaces and causing painful recurrent diseases. The innate and adaptive mucosal immunities to herpes infections and disease remain to be fully characterized. The understanding of innate and adaptive immune mechanisms operating at muco-cutaneous surfaces is fundamental to the design of next-generation herpes vaccines. In this paper, the phenotypic and functional properties of innate and adaptive mucosal immune cells, their role in antiherpes immunity, and immunopathology are reviewed. The progress and limitations in developing a safe and efficient mucosal herpes vaccine are discussed.

Herpes keratitis

Herpes simplex virus-1 (HSV-1) infects the majority of the world's population. These infections are often asymptomatic, but ocular HSV-1 infections cause multiple pathologies with perhaps the most destructive being herpes stromal keratitis (HSK). HSK lesions, which are immunoinflammatory in nature, can recur throughout life and often cause progressive corneal scaring resulting in visual impairment. Current treatment involves broad local immunosuppression with topical steroids along with antiviral coverage. Unfortunately, the immunopathologic mechanisms defined in animal models of HSK have not yet translated into improved therapy. Herein, we review the clinical epidemiology and pathology of the disease and summarize the large amount of basic research regarding the immunopathology of HSK. We examine the role of the innate and adaptive immune system in the clearance of virus and the destruction of the normal corneal architecture that is typical of HSK. Our goal is to define current knowledge of the pathogenic mechanisms and recurrent nature of HSK and identify areas that require further study.

Of mice and not humans: how reliable are animal models for evaluation of herpes CD8(+)-T cell-epitopes-based immunotherapeutic vaccine candidates?

Herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2)-specific CD8(+) T cells that reside in sensory ganglia, appear to control recurrent herpetic disease by aborting or reducing spontaneous and sporadic reactivations of latent virus. A reliable animal model is the ultimate key factor to test the efficacy of therapeutic vaccines that boost the level and the quality of sensory ganglia-resident CD8(+) T cells against spontaneous herpes reactivation from sensory neurons, yet its relevance has been often overlooked. Herpes vaccinologists are hesitant about using mouse as a model in pre-clinical development of therapeutic vaccines because they do not adequately mimic spontaneous viral shedding or recurrent symptomatic diseases, as occurs in human. Alternatives to mouse models are rabbits and guinea pigs in which reactivation arise spontaneously with clinical herpetic features relevant to human disease. However, while rabbits and guinea pigs develop spontaneous HSV reactivation and recurrent ocular and genital disease none of them can mount CD8(+) T cell responses specific to Human Leukocyte Antigen- (HLA-)restricted epitopes. In this review, we discuss the advantages and limitations of these animal models and describe a novel "humanized" HLA transgenic rabbit, which shows spontaneous HSV-1 reactivation, recurrent ocular disease and mounts CD8(+) T cell responses to HLA-restricted epitopes. Adequate investments are needed to develop reliable preclinical animal models, such as HLA class I and class II double transgenic rabbits and guinea pigs to balance the ethical and financial concerns associated with the rising number of unsuccessful clinical trials for therapeutic vaccine formulations tested in unreliable mouse models.

Infection, immunity and the neuroendocrine response

The Central Nervous (CNS) and Immune Systems (IS) are the two major adaptive systems which respond rapidly to numerous challenges that are able to compromise health. The defensive response strictly linking innate to acquired immunity, works continuously to limit pathogen invasion and damage. The efficiency of the innate response is crucial for survival and for an optimum priming of acquired immunity. During infection, the immune response is modulated by an integrated neuro-immune network which potentiates innate immunity, controls potential harmful effects and also addresses metabolic and nutritional modifications supporting immune function. In the last decade much knowledge has been gained on the molecular signals that orchestrate this integrated adaptive response, with focus on the systemic mediators which have a crucial role in driving and controlling an efficient protective response. These mediators are also able to signal alterations and control pathway dysfunctions which may be involved in the persistence and/or overexpression of inflammation that may lead to tissue damage and to a negative metabolic impact, causing retarded growth. This review aims to describe some important signalling pathways which drive bidirectional communication between the Immune and Nervous Systems during infection. Particular emphasis is placed on pro-inflammatory cytokines, immunomodulator hormones such as Glucocorticoids (GCs), Growth hormone (GH), Insulin-like Growth Factor-1 (IGF-1), and Leptin, as well as nutritional factors such as Zinc (Zn). Finally, the review includes up-to-date information on this neuroimmune cross-talk in domestic animals. Data in domestic animal species are still limited, but there are several exciting areas of research, like the potential interaction pathways between mediators (i.e. cytokine-HPA regulation, IL-6-GCS-Zn, cytokines-GH/IGF-1, IL-6-GH-Leptin and thymus activity) that are or could be promising topics of future research in veterinary medicine.

Chronic restraint stress impairs T-cell immunity and promotes tumor progression in mice

Long-term exposure to stressful situations can affect the immune system. The T-cell response is an important component of anti-tumoral immunity. Hence, impairment of the immune function induced by a chronic stressor has been postulated to alter the immunosurveillance of tumors, thus leading to a worse neoplastic prognosis. Here, we show that chronic restraint stress affects T-cell mediated immunity in mice. This was evidenced by a decrease of mitogen-induced T-cell proliferation, a reduction in CD4(+)T lymphocyte number and a decrease of tumor necrosis factor-alpha (TNF-alpha) and Interferon-gamma (IFN-gamma) production in stressed mice. Additionally, mice subjected to chronic restraint stress displayed an enhancement of tumor growth in a syngeneic lymphoma model, i.e. an increase of tumor proliferation and a reduction of animal survival. Finally, stressed mice had a reduced specific cytotoxic response against these tumor cells. These results suggest that chronic exposure to stress promotes cancer establishment and subsequent progression, probably by depressing T-cell mediated immunity. The T-cell immunity impairment as well as the tumor progression enhancement emphasize the importance of the therapeutic management of stress to improve the prognosis of cancer patients.

Corticosterone impairs dendritic cell maturation and function

Dendritic cells (DC) play a critical role in initiating and directing adaptive immune responses against pathogens and tumours. Immature DC are thought to act as sentinels in peripheral tissues where their main function is to capture antigen at sites of infection, whereas mature DC are highly efficient at priming T-cell-mediated immune responses against infectious pathogens. The DC maturation process is thought to be an important step in the efficient generation of cytotoxic T lymphocytes (CTL). It is well established that many aspects of immune function, including CTL-mediated antiviral immunity, are modulated by neuroendocrine-derived products. Corticosterone (CORT), an adrenal hormone produced at increased concentrations during a stress response, has been shown to play a role in impaired CTL responses in stressed animals, leading to high mortality in mice normally resistant to viral infection. While direct effects of neuroendocrine mediators on CTL have been studied, little is known about their effects on DC that are critical for CTL priming. Here, we found that physiologically relevant concentrations of CORT, acting via the glucocorticoid receptor, functionally compromise DC maturation. DC exposed to CORT remained phenotypically and functionally immature after stimulation with lipopolysaccharide and were impaired for the production of interleukin (IL)-6, IL-12, and tumour necrosis factor-alpha. These effects were biologically significant, as CORT treatment resulted in a marked reduction in the ability of DC to prime naive CD8(+) T cells in vivo. These findings offer a potential mechanism underlying stress-associated immunosuppression.

Psychological stress compromises CD8+ T cell control of latent herpes simplex virus type 1 infections

Recurrent HSV-1 ocular disease results from reactivation of latent virus in trigeminal ganglia, often following immunosuppression or exposure to a variety of psychological or physical stressors. HSV-specific CD8+ T cells can block HSV-1 reactivation from latency in ex vivo trigeminal ganglia cultures through production of IFN-gamma. In this study, we establish that either CD8+ T cell depletion or exposure to restraint stress permit HSV-1 to transiently escape from latency in vivo. Restraint stress caused a reduction of TG-resident HSV-specific CD8+ T cells and a functional compromise of those cells that survive. Together, these effects of stress resulted in an approximate 65% reduction of cells capable of producing IFN-gamma in response to reactivating virus. Our findings demonstrate persistent in vivo regulation of latent HSV-1 by CD8+ T cells, and strongly support the concept that stress induces HSV-1 reactivation from latency at least in part by compromising CD8+ T cell surveillance of latently infected neurons.

Effect of electric foot shock and psychological stress on activities of murine splenic natural killer and lymphokine-activated killer cells, cytotoxic T lymphocytes, natural killer receptors and mRNA transcripts for granzymes and perforin

To explore the mechanism of stress-induced inhibition of natural killer (NK) activity, female C57BL/6 mice were stimulated by electric foot shock and psychological stress for 7 days consecutively. The shocked mice received scrambled, uncontrollable, inescapable 0.6 mA electric shocks in a communication box 120 times during 60 min. The mice in the psychological stress group were put into the communication box without electric foot shock. The plasma corticosterone level in both stressed groups was significantly higher than that in controls on days 1, 3, 5 and 7 and showed the highest level on day 3 in the foot shock stress. According to these results, therefore, we investigated the effect of stress on immunological function on day 3, and measured body weight, weight of the spleen, number of splenocytes, splenic NK, lymphokine-activated killer (LAK) and cytotoxic T lymphocyte (CTL) activities, NK receptors, and mRNA transcripts for granzymes A and B and perforin in splenocytes. The NK, LAK and CTL activities, and NK receptors in mice with both types of stress were significantly decreased compared to those of the control mice, but the decreases were greater in the foot-shocked mice than in the psychological-stress mice. The mRNA transcripts for granzyme A and perforin were significantly decreased only in the foot-shocked mice. On the other hand, the foot-shock stress increased granzyme B. The above findings suggest that stress induced inhibition of NK, LAK and CTL activities partially via affecting NK receptors, granzymes and perforin.

Effect of intense wrestling exercise on leucocytes and adhesion molecules in adolescent boys

BACKGROUND

In adults, exercise is a powerful and natural stimulator of immune cells and adhesion molecules. Far less is known about exercise responses during childhood and adolescence and whether or not exercise in "real life" activities of healthy adolescents influences immune responses.

OBJECTIVE

To determine if strenuous exercise leads to significant changes in leucocyte number and adhesion molecule expression in adolescent boys.

METHODS

Eleven healthy, high school boys, aged 14-18.5 years, performed a single, typical, 1.5 hour wrestling practice session. Blood was sampled before and after the session. Flow cytometry was used to evaluate changes in immune responses.

RESULTS

The exercise led to significant (p<0.05) and robust increases in granulocytes, monocytes, and all lymphocyte subpopulations. The most significant changes were observed for natural killer cells (p<0.0005). The number of T cytotoxic and T helper cells expressing CD62L increased significantly (p<0.002 and p<0.0005 respectively), as did the number of T cytotoxic and T helper cells not expressing CD62L (p<0.003 and p<0.009 respectively). The density of CD62L on lymphocytes decreased significantly with exercise (p<0.0005), whereas CD11a (p<0.01) and CD54 (p<0.01) increased.

CONCLUSIONS

The data show that an intense wrestling bout in adolescent boys leads to profound stimulation of the immune system. The role of these common changes in overall immune status and the development of the immune and haemopoietic systems has yet to be determined.

Stress-related modulation of matrix metalloproteinase expression

Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs), whose expression can be controlled by cytokines, play a role in extracellular matrix remodeling in physiological and pathological processes. Using a blister chamber wound model on UV-B-exposed human forearm skin, we examined whether stress or mood-associated neuroendocrine alteration is sufficient to modulate MMP and TIMP expression. We did not find evidence that depressive symptoms were reliably associated with modulation of either MMP or TIMP expression. However, we did find that activation of the hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal medullary (SAM) axes can modulate levels of MMPs. A positive association between plasma norepinephrine levels and MMP-2 protein levels, and a negative correlation between plasma cortisol levels and MMP-2 levels were found. The data suggest that activation of the HPA and SAM axes, even in individuals within the normal range of depressive symptoms, could mediate MMP levels and wound healing in blister wounds.

Systemic vs. local cytokine and leukocyte responses to unilateral wrist flexion exercise

We hypothesized that brief exercise of a small muscle group would lead to local rather than systemic alterations in cytokines, peripheral blood mononuclear cells, and mediators of angiogenesis. Fifteen men and eight women (age range 22-36 yr old) performed 10 min of unilateral wrist flexion exercise. Blood was sampled from venous catheters in the resting and exercising arm at baseline, at the end of exercise, and at 10, 30, 60, and 120 min after exercise. Lactate was significantly elevated in the exercising arm (+276 +/- 35%; P < 0.0005) with no change in the resting arm. In contrast, increases in both arms were observed for interleukin-6 (+139 +/- 51%; P < 0.0005), growth hormone (+1,104 +/- 284%; P < 0.003), natural killer cells (+81 +/- 9%; P < 0.0005), and lymphocytes expressing CD62L, CD11a, and CD54. There were no significant differences in these increases between the resting and exercising arm. Catecholamines increased in both arms [epinephrine peak increase, +226 +/- 36% (P < 0.001); norepinephrine peak increase, +90 +/- 15% (P < 0.01)]. Fibroblast growth factor-2 initially decreased with exercise in both arms, and this was followed by a rebound increase. Vascular endothelial growth factor demonstrated a small but significant increase in both arms (+124 +/- 31%; P < 0.05). Brief, low-intensity exercise leads to a systemic rather than local response of mediators that could be involved in inflammation, repair, or angiogenic adaptation to physical activity.

The effects of stress on memory cytotoxic T lymphocyte-mediated protection against herpes simplex virus infection at mucosal sites

Psychological stress has been shown to affect many components of the innate and adaptive immune responses to a variety of pathogens including herpes simplex virus (HSV). Mucosal tissues are clinically relevant sites of infection with HSV as well as with many other common pathogens. However, there is a scarcity of experimental evidence that stress affects mucosal immunity. We have taken advantage of a murine model of HSV-specific immune protection that is mediated by only memory cytotoxic T lymphocytes (CTLm) specific for a single CTL recognition epitope within glycoprotein B of HSV-1 (gB498-505). This CTLm population is elicited by vaccination with a recombinant vaccinia virus, which expresses this epitope in the absence of any other HSV-encoded antigens. We report here that stress reduces the ability of gB498-505-specific CTLm to protect against a lethal intranasal or intravaginal HSV infection. Also, stress decreases the ability of these CTLm to limit virus levels at the mucosal site of infection but does not have a significant effect on the levels of virus in the innervating sensory ganglia. Finally, stress decreases protection against HSV-mediated pathology of the vaginal epithelium. These studies are the first to examine the effects of stress on CTLm activation and function in vivo.

Chemical sympathectomy alters cytotoxic T lymphocyte responses to herpes simplex virus infection

Numerous studies have sought to delineate the impact of neuroendocrine function on overall immune responsiveness. Using various murine models, we and others have previously shown that both adrenal-dependent and adrenal-independent mechanisms regulate components of the primary and memory cellular immune responses to herpes simplex virus type 1 (HSV-1) infection. We have extended these studies by determining the impact of 6-hydroxydopamine (6-OHDA)-induced peripheral sympathetic denervation on these responses. C57BL/6 mice treated with 6-OHDA (200 mg/kg) were inhibited in their ability to generate primary, HSV-specific cytotoxic T lymphocytes (CTL) in response to HSV infection. Sympathectomy also suppressed the activation and function of HSV-specific memory CTL (CTLm). In addition, administration of 6-OHDA resulted in a transient but substantial increase in levels of circulating corticosterone and hypothalamic Fos expression. Together, these findings suggest that peripheral sympathetic denervation may modulate immune function via activation of the hypothalamic-pituitary-adrenal (HPA) axis.

Aberrant nuclear expression of AP-1 and NFkappaB in lymphocytes of women stressed by the experience of breast biopsy

We have investigated the expression of AP-1 and NFkappaB in peripheral blood lymphocytes of women scheduled for breast biopsy. Samples were collected when women were informed of the need for biopsy (prebiopsy, T1, 5-7 days prior to the actual biopsy) and 7-10 days after they learned the result of their biopsy (postbiopsy, T2). At the time of blood collection, psychological stress was evaluated using Speilberger's State Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Women scheduled to undergo breast biopsy reported significant increases in anxiety (STAI) and mood disturbance (POMS). Gel shift mobility assays showed that mitogen stimulated peripheral blood lymphocytes of these women were less capable of the nuclear expression of AP-1 or NFkappaB at T1. Similar assessments, 7-10 days after the women learned of the results of their breast biopsy, showed these same women to have a marked reduction in anxiety and mood disturbance and an increased nuclear translocation of AP-1 and NFkappaB. These results show a significant decrease in nuclear AP-1 and NFkappaB expression during the period of emotional distress prior to biopsy with a return of nuclear transcription activity to normal levels when distress was relieved. Several studies have correlated increased psychological stress with decreased immune function. The results of this study suggest that psychological stress may mediate immunosuppression by altering the expression of the transcription factors, AP-1 and NFkappaB.

Plasma corticosterone and immune reactivity in restrained female C3H mice

Psychological stressors are known to stimulate the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system resulting in the release of corticosterone and catecholamines respectively. They have also been reported to induce cytokine production. All these molecules affect various immune parameters and can alter overall immune competence of the individual. The purpose of this investigation was to study the regulation of the production of corticosterone during stress and its possible effects on immune reactivity. In a first series of experiments, the possible regulation of corticosterone production by interleukin (IL)-1beta and peripheral catecholamines during restraint was assessed using a pharmacological approach in mice. Plasma IL-1beta concentrations remained at basal after 1-h restraint and the stress-induced increase of plasma corticosterone was not modified by a peripheral injection of an IL-1 receptor antagonist (IL-1ra). By contrast, chemical sympathectomy potentiated the restraint-induced increase in plasma corticosterone concentration, this potentiation being reversed by IL-1ra. In a second series of experiments, the role of corticosterone in stress-immune relationships was studied in adrenalectomized mice subjected to restraint and immunized with sheep erythrocytes. Non-specific immunity, i.e. proliferation of splenocytes and thymocytes and plasma levels of IL-1beta, as well as specific immunity, i.e. antibody production and delayed hypersensitivity, were not altered after 2-h restraint. Adrenalectomy failed to induce immune effects in stressed animals, except that delayed hypersensitivity was stronger in adrenalectomized animals, revealing that the high levels of corticosterone produced during stress have an anti-inflammatory activity. The present data show that the stress-induced production of corticosterone was modulated by both peripheral catecholamines and IL-1beta. However, this production of corticosterone was unable to modulate immune reactivity except delayed hypersensitivity.