Immunogenic dendritic cells primed by social defeat enhance adaptive immunity to influenza A virus

SIR+ models: accounting for interaction-dependent disease susceptibility in the planning of public health interventions

Avoiding physical contact is regarded as one of the safest and most advisable strategies to follow to reduce pathogen spread. The flip side of this approach is that a lack of social interactions may negatively affect other dimensions of health, like induction of immunosuppressive anxiety and depression or preventing interactions of importance with a diversity of microbes, which may be necessary to train our immune system or to maintain its normal levels of activity. These may in turn negatively affect a population's susceptibility to infection and the incidence of severe disease. We suggest that future pandemic modelling may benefit from relying on 'SIR+ models': epidemiological models extended to account for the benefits of social interactions that affect immune resilience. We develop an SIR+ model and discuss which specific interventions may be more effective in balancing the trade-off between minimizing pathogen spread and maximizing other interaction-dependent health benefits. Our SIR+ model reflects the idea that health is not just the mere absence of disease, but rather a state of physical, mental and social well-being that can also be dependent on the same social connections that allow pathogen spread, and the modelling of public health interventions for future pandemics should account for this multidimensionality.

A Review of the Effects of Some Extrinsic Factors on Mice Used in Research

Animals have been used in research for over 2,000 y. From very crude experiments conducted by ancient scholars, animal research, as a science, was refined over hundreds of years to what we know it as today. However, the housing conditions of animals used for research did not improve significantly until less than 100 years ago when guidelines for housing research animals were first published. In addition, it was not until relatively recently that some extrinsic factors were recognized as a research variable, even when animals were housed under recommended guidelines. For example, temperature, humidity, light, noise, vibration, diet, water, caging, bedding, etc., can all potentially affect research using mice, contributing the inability of others to reproduce published findings. Consequently, these external factors should be carefully considered in the design, planning, and execution of animal experiments. In addition, as recommended by others, the housing and husbandry conditions of the animals should be described in detail in publications resulting from animal research to improve study reproducibility. Here, we briefly review some common, and less common, external factors that affect research in one of the most popular animal models, the mouse.

Asthma and posttraumatic stress disorder (PTSD): Emerging links, potential models and mechanisms

Posttraumatic stress disorder (PTSD) is a highly prevalent, debilitating mental health condition. A better understanding of contributory neurobiological mechanisms will lead to effective treatments, improving quality of life for patients. Given that not all trauma-exposed individuals develop PTSD, identification of pre-trauma susceptibility factors that can modulate posttraumatic outcomes is important. Recent clinical evidence supports a strong link between inflammatory conditions and PTSD. A particularly strong association has been reported between asthma and PTSD prevalence and severity. Unlike many other PTSD-comorbid inflammatory conditions, asthma often develops in children, sensitizing them to subsequent posttraumatic pathology throughout their lifetime. Currently, there is a significant need to understand the neurobiology, shared mechanisms, and inflammatory mediators that may contribute to comorbid asthma and PTSD. Here, we provide a translational perspective of asthma and PTSD risk and comorbidity, focusing on clinical associations, relevant rodent paradigms and potential mechanisms that may translate asthma-associated inflammation to PTSD development.

Dendritic Cells: Neglected Modulators of Peripheral Immune Responses and Neuroinflammation in Mood Disorders?

Affective disorders (AD) including major depressive disorder (MDD) and bipolar disorder (BD) are common mood disorders associated with increased disability and poor health outcomes. Altered immune responses characterized by increased serum levels of pro-inflammatory cytokines and neuroinflammation are common findings in patients with AD and in corresponding animal models. Dendritic cells (DCs) represent a heterogeneous population of myeloid cells that orchestrate innate and adaptive immune responses and self-tolerance. Upon sensing exogenous and endogenous danger signals, mature DCs secrete proinflammatory factors, acquire migratory and antigen presenting capacities and thus contribute to neuroinflammation in trauma, autoimmunity, and neurodegenerative diseases. However, little is known about the involvement of DCs in the pathogenesis of AD. In this review, we summarize the current knowledge on DCs in peripheral immune responses and neuroinflammation in MDD and BD. In addition, we consider the impact of DCs on neuroinflammation and behavior in animal models of AD. Finally, we will discuss therapeutic perspectives targeting DCs and their effector molecules in mood disorders.

A new perspective for mitigation of SARS-CoV-2 infection: priming the innate immune system for viral attack

The course of infection by SARS-CoV-2 frequently includes a long asymptomatic period, followed in some individuals by an immune dysregulation period that may lead to complications and immunopathology-induced death. This course of disease suggests that the virus often evades detection by the innate immune system. We suggest a novel therapeutic approach to mitigate the infection's severity, probability of complications and duration. We propose that priming an individual's innate immune system for viral attack shortly before it is expected to occur may allow pre-activation of the preferable trajectory of immune response, leading to early detection of the virus. Priming can be carried out, for example, by administering a standard vaccine or another reagent that elicits a broad anti-viral innate immune response. By the time that the expected SARS-CoV-2 infection occurs, activation cascades will have been put in motion and levels of immune factors needed to combat the infection will have been elevated. The infection would thus be cleared faster and with less complication than otherwise, alleviating adverse clinical outcomes at the individual level. Moreover, priming may also mitigate population-level risk by reducing need for hospitalizations and decreasing the infectious period of individuals, thus slowing the spread and reducing the impact of the epidemic. In view of the latter consideration, our proposal may have a significant epidemiological impact even if applied primarily to low-risk individuals, such as young adults, who often show mild symptoms or none, by shortening the period during which they unknowingly infect others. The proposed view is, at this time, an unproven hypothesis. Although supported by robust bio-medical reasoning and multiple lines of evidence, carefully designed clinical trials are necessary.

From early adversities to immune activation in psychiatric disorders: the role of the sympathetic nervous system

Increased peripheral levels of cytokines and central microglial activation have been reported in patients with psychiatric disorders. The degree of both innate and adaptive immune activation is also associated with worse clinical outcomes and poor treatment response in these patients. Understanding the possible causes and mechanisms leading to this immune activation is therefore an important and necessary step for the development of novel and more effective treatment strategies for these patients. In this work, we review the evidence of literature pointing to childhood trauma as one of the main causes behind the increased immune activation in patients with psychiatric disorders. We then discuss the potential mechanisms linking the experience of early life adversity (ELA) to innate immune activation. Specifically, we focus on the innervation of the bone marrow from sympathetic nervous system (SNS) as a new and emerging mechanism that has the potential to bridge the observed increases in both central and peripheral inflammatory markers in patients exposed to ELA. Experimental studies in laboratory rodents suggest that SNS activation following early life stress exposure causes a shift in the profile of innate immune cells, with an increase in proinflammatory monocytes. In turn, these cells traffic to the brain and influence neural circuitry, which manifests as increased anxiety and other relevant behavioural phenotypes. To date, however, very few studies have been conducted to explore this candidate mechanism in humans. Future research is also needed to clarify whether these pathways could be partially reversible to improve prevention and treatment strategies in the future.

A Pilot Study Using a Multistaged Integrated Analysis of Gene Expression and Methylation to Evaluate Mechanisms for Evening Fatigue in Women Who Received Chemotherapy for Breast Cancer

CONTEXT

Fatigue is the most common symptom associated with cancer and its treatment. Investigation of molecular mechanisms associated with fatigue may identify new therapeutic targets.

OBJECTIVE

The objective of this pilot study was to evaluate the relationships between gene expression and methylation status and evening fatigue severity in women with breast cancer who received chemotherapy.

METHODS

Latent class analysis (LCA) was used to identify evening fatigue phenotypes. In this analysis, the lowest (i.e., moderate, n = 7) and highest (i.e., very high, n = 29) fatigue-severity classes identified using LCA were analyzed via two stages. First, a total of 32,609 transcripts from whole blood were evaluated for differences in expression levels between the classes. Next, 637 methylation sites located within the putative transcription factor binding sites for those genes demonstrating differential expression were evaluated for differential methylation state between the classes.

RESULTS

A total of 89 transcripts in 75 unique genes were differentially expressed between the moderate (the lowest fatigue-severity class identified) and very high evening fatigue classes. In addition, 23 differentially methylated probes and three differentially methylated regions were found between the moderate and very high evening fatigue classes.

CONCLUSIONS

Using a multistaged integrated analysis of gene expression and methylation, differential methylation was identified in the regulatory regions of genes associated with previously hypothesized mechanisms for fatigue, including inflammation, immune function, neurotransmission, circadian rhythm, skeletal muscle energy, carbohydrate metabolism, and renal function as well as core biological processes including gene transcription and the cell-cycle regulation.

The role of stress in the mosaic of autoimmunity: An overlooked association

Stress is defined as the pscyophysiological reaction in which the steady state is disturbed or threatened. Stress is not always perceived as a negative response. Stress results when environmental demands exceed an individuals' adaptive capacities. Autoimmune diseases are heterogeneous group of chronic diseases which occur secondary to loss of self antigen tolerance. The etiopathogenesis of autoimmune disease is uncertain. Genetic factors as well as environmental factors appear to interplay, leading to a cascade of events resulting in disease onset. Stress has been postulated to play a role in disease onset in the genetically susceptible patients. During the stress response, catecholamines and glucocorticoids are released from locus coeruleus and adrenal gland. These biomolecules exert control over various immune cells in the innate and adaptive arms of the immune system, thereby altering the cytokine profile released. The increase of IL-4 promotes T-helper 2 (T_h2) cell differentiation, while the decrease in IL-12 and the increased IL-10 production reduce the number of T-helper 1 (T_h1) cells. The relationship between stress and autoimmune diseases is intricate. Stress has been shown to be associated with disease onset, and disease exacerbations in rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, Graves' disease as well as other autoimmune conditions. In certain conditions such as psoriasis, stress has been implicated in delaying lesion clearance upon the application of standard treatment regimes. Finally, psychological therapy and cognitive behavioral therapy aimed to reduce stress levels was shown to be effective in influencing better outcomes in many autoimmune diseases. The purpose of this paper is to closer inspect the clinical evidence regarding the role of stress on influencing the various aspects of disease entities.

Alterations of the Innate Immune System in Susceptibility and Resilience After Social Defeat Stress

Dysregulation of innate immune responses has frequently been reported in stress-associated psychiatric disorders such as major depression. In mice, enhanced circulating cytokine levels as well as altered innate immune cell numbers have been found after stress exposure. In addition, stress-induced recruitment of peripheral monocytes to the brain has been shown to promote anxiety-like behavior. However, it is yet unclear whether specific differences in the innate immune system are associated with stress susceptibility or resilience in mice. Utilizing chronic social defeat, a model of depression and stress vulnerability, we characterized peripheral and brain-invading myeloid cells in stress-susceptible and resilient animals. In all defeated animals, we found reduced percentages of CD11c⁺ dendritic cells (DCs) by flow cytometry in the spleen when compared to non-defeated controls. Exclusively in susceptible mice conventional DCs of the spleen showed up-regulated expression of MHC class II and co-stimulatory CD80 molecules pointing toward an enhanced maturation phenotype of these cells. Susceptible, but not resilient animals further exhibited an increase in inflammatory Ly6C^hi monocytes and higher numbers of spleen-derived CD11b⁺ cells that produced the proinflammatory cytokine tumor necrosis factor (TNF) upon lipopolysaccharide (LPS) stimulation. Increased percentages of peripheral CD45^hi CD11b⁺ cells immigrated into the brain of defeated mice, regardless of resilience or susceptibility. However, cellular infiltrates in the brain of susceptible mice contained higher percentages of CC chemokine receptor 2 (CCR2⁺) Ly6C^hi monocytes representing an inflammatory phenotype. Thus, we defined specific stress-related immune signatures involving conventional DCs and inflammatory Ly6C^hi monocytes in susceptible and resilient mice. Together, our findings suggest an impact of the innate immune system in vulnerability to stress-related disorders such as major depression.

Pathogen-Host Defense in the Evolution of Depression: Insights into Epidemiology, Genetics, Bioregional Differences and Female Preponderance

Significant attention has been paid to the potential adaptive value of depression as it relates to interactions with people in the social world. However, in this review, we outline the rationale of why certain features of depression including its environmental and genetic risk factors, its association with the acute phase response and its age of onset and female preponderance appear to have evolved from human interactions with pathogens in the microbial world. Approaching the relationship between inflammation and depression from this evolutionary perspective yields a number of insights that may reveal important clues regarding the origin and epidemiology of the disorder as well as the persistence of its risk alleles in the modern human genome.

Rehmannia glutinosa polysaccharide liposome as a novel strategy for stimulating an efficient immune response and their effects on dendritic cells

Nanomedicine, the medical application of nanotechnology, promises a seemingly limitless range of applications from drug delivery to adjuvants and therapeutics. Our current research is focused on natural polymer-based liposome adjuvants. With the aim of inducing protective and long-lasting immunity, the immunological adjuvant activity of Rehmannia glutinosa polysaccharide liposome (RGPL) was investigated. In vivo, the splenic lymphocyte proliferation ratios and ovalbumin-specific immunoglobulin G titers of ovalbumin-RGPL-vaccinated mice were significantly upregulated. In draining lymph nodes, the expression of MHC II⁺CD11c⁺ and CD86⁺CD11c⁺ was increased by RGPL; in addition, the percentages of central memory cells (T_CM) and effector memory cells (T_EM) were also elevated. RGPL could effectively provide adequate antigen exposure in lymph nodes. In vitro, RGPL could promote dendritic cell maturation and enhance dendritic cell functions, such as the mixed lymphocyte reaction and antigen presentation. Overall, the results demonstrated that RGPL has the potential to act as an effective controlled release vaccine adjuvant.

Glucocorticoids enhance the in vivo migratory response of human monocytes

Glucocorticoids (GCs) are best known for their potent anti-inflammatory effects. However, an emerging model for glucocorticoid (GC) regulation of in vivo inflammation also includes a delayed, preparatory effect that manifests as enhanced inflammation following exposure to an inflammatory stimulus. When GCs are transiently elevated in vivo following exposure to a stressful event, this model proposes that a subsequent period of increased inflammatory responsiveness is adaptive because it enhances resistance to a subsequent stressor. In the present study, we examined the migratory response of human monocytes/macrophages following transient in vivo exposure to stress-associated concentrations of cortisol. Participants were administered cortisol for 6h to elevate in vivo cortisol levels to approximate those observed during major systemic stress. Monocytes in peripheral blood and macrophages in sterile inflammatory tissue (skin blisters) were studied before and after exposure to cortisol or placebo. We found that exposure to cortisol induced transient upregulation of monocyte mRNA for CCR2, the receptor for monocyte chemotactic protein-1 (MCP-1/CCL2) as well as for the chemokine receptor CX3CR1. At the same time, mRNA for the transcription factor IκBα was decreased. Monocyte surface expression of CCR2 but not CX3CR1 increased in the first 24h after cortisol exposure. Transient exposure to cortisol also led to an increased number of macrophages and neutrophils in fluid derived from a sterile inflammatory site in vivo. These findings suggest that the delayed, pro-inflammatory effects of cortisol on the human inflammatory responses may include enhanced localization of effector cells at sites of in vivo inflammation.

Gene Expression Profiling of Evening Fatigue in Women Undergoing Chemotherapy for Breast Cancer

Moderate-to-severe fatigue occurs in up to 94% of oncology patients undergoing active treatment. Current interventions for fatigue are not efficacious. A major impediment to the development of effective treatments is a lack of understanding of the fundamental mechanisms underlying fatigue. In the current study, differences in phenotypic characteristics and gene expression profiles were evaluated in a sample of breast cancer patients undergoing chemotherapy (CTX) who reported low (n = 19) and high (n = 25) levels of evening fatigue. Compared to the low group, patients in the high evening fatigue group reported lower functional status scores, higher comorbidity scores, and fewer prior cancer treatments. One gene was identified as upregulated and 11 as downregulated in the high evening fatigue group. Gene set analysis found 24 downregulated and 94 simultaneously up- and downregulated pathways between the two fatigue groups. Transcript origin analysis found that differential expression (DE) originated primarily from monocytes and dendritic cell types. Query of public data sources found 18 gene expression experiments with similar DE profiles. Our analyses revealed that inflammation, neurotransmitter regulation, and energy metabolism are likely mechanisms associated with evening fatigue severity; that CTX may contribute to fatigue seen in oncology patients; and that the patterns of gene expression may be shared with other models of fatigue (e.g., physical exercise and pathogen-induced sickness behavior). These results suggest that the mechanisms that underlie fatigue in oncology patients are multifactorial.

Inflammation and lithium: clues to mechanisms contributing to suicide-linked traits

Suicide is one of the leading causes of death in the United States, yet it remains difficult to understand the mechanistic provocations and to intervene therapeutically. Stress is recognized as a frequent precursor to suicide. Psychological stress is well established to cause activation of the inflammatory response, including causing neuroinflammation, an increase of inflammatory molecules in the central nervous system (CNS). Neuroinflammation is increasingly recognized as affecting many aspects of CNS functions and behaviors. In particular, much evidence demonstrates that inflammatory markers are elevated in traits that have been linked to suicidal behavior, including aggression, impulsivity and depression. Lithium is recognized as significantly reducing suicidal behavior, is anti-inflammatory and diminishes aggression, impulsivity and depression traits, each of which is associated with elevated inflammation. The anti-inflammatory effects of lithium result from its inhibition of glycogen synthase kinase-3 (GSK3). GSK3 has been demonstrated to strongly promote inflammation, aggressive behavior in rodents and depression-like behaviors in rodents, whereas regulation of impulsivity by GSK3 has not yet been investigated. Altogether, evidence is building supporting the hypothesis that stress activates GSK3, which in turn promotes inflammation, and that inflammation is linked to behaviors associated with suicide, including particularly aggression, impulsivity and depression. Further investigation of these links may provide a clearer understanding of the causes of suicidal behavior and provide leads for the development of effective preventative interventions, which may include inhibitors of GSK3.

The effects of mind-body therapies on the immune system: meta-analysis

Importance

Psychological and health-restorative benefits of mind-body therapies have been investigated, but their impact on the immune system remain less defined.

Objective

To conduct the first comprehensive review of available controlled trial evidence to evaluate the effects of mind-body therapies on the immune system, focusing on markers of inflammation and anti-viral related immune responses.

Methods

Data sources included MEDLINE, CINAHL, SPORTDiscus, and PsycINFO through September 1, 2013. Randomized controlled trials published in English evaluating at least four weeks of Tai Chi, Qi Gong, meditation, or Yoga that reported immune outcome measures were selected. Studies were synthesized separately by inflammatory (n = 18), anti-viral related immunity (n = 7), and enumerative (n = 14) outcomes measures. We performed random-effects meta-analyses using standardized mean difference when appropriate.

Results

Thirty-four studies published in 39 articles (total 2, 219 participants) met inclusion criteria. For inflammatory measures, after 7 to 16 weeks of mind-body intervention, there was a moderate effect on reduction of C-reactive protein (effect size [ES], 0.58; 95% confidence interval [CI], 0.04 to 1.12), a small but not statistically significant reduction of interleukin-6 (ES, 0.35; 95% CI, −0.04 to 0.75), and negligible effect on tumor necrosis factor-α (ES, 0.21; 95% CI, −0.15 to 0.58). For anti-viral related immune and enumerative measures, there were negligible effects on CD4 counts (ES, 0.15; 95% CI, −0.04 to 0.34) and natural killer cell counts (ES, 0.12, 95% CI −0.21 to 0.45). Some evidence indicated mind-body therapies increase immune responses to vaccination.

Conclusions

Mind-body therapies reduce markers of inflammation and influence virus-specific immune responses to vaccination despite minimal evidence suggesting effects on resting anti-viral or enumerative measures. These immunomodulatory effects, albeit incomplete, warrant further methodologically rigorous studies to determine the clinical implications of these findings for inflammatory and infectious disease outcomes.

Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via β-adrenergic induction of myelopoiesis

Across a variety of adverse life circumstances, such as social isolation and low socioeconomic status, mammalian immune cells have been found to show a conserved transcriptional response to adversity (CTRA) involving increased expression of proinflammatory genes. The present study examines whether such effects might stem in part from the selective up-regulation of a subpopulation of immature proinflammatory monocytes (Ly-6c(high) in mice, CD16(-) in humans) within the circulating leukocyte pool. Transcriptome representation analyses showed relative expansion of the immature proinflammatory monocyte transcriptome in peripheral blood mononuclear cells from people subject to chronic social stress (low socioeconomic status) and mice subject to repeated social defeat. Cellular dissection of the mouse peripheral blood mononuclear cell transcriptome confirmed these results, and promoter-based bioinformatic analyses indicated increased activity of transcription factors involved in early myeloid lineage differentiation and proinflammatory effector function (PU.1, NF-κB, EGR1, MZF1, NRF2). Analysis of bone marrow hematopoiesis confirmed increased myelopoietic output of Ly-6c(high) monocytes and Ly-6c(intermediate) granulocytes in mice subject to repeated social defeat, and these effects were blocked by pharmacologic antagonists of β-adrenoreceptors and the myelopoietic growth factor GM-CSF. These results suggest that sympathetic nervous system-induced up-regulation of myelopoiesis mediates the proinflammatory component of the leukocyte CTRA dynamic and may contribute to the increased risk of inflammation-related disease associated with adverse social conditions.

Psychosocial stress and inflammation in cancer

Stress-induced immune dysregulation results in significant health consequences for immune related disorders including viral infections, chronic autoimmune disease, and tumor growth and metastasis. In this mini-review we discuss the sympathetic, neuroendocrine and immunologic mechanisms by which psychosocial stress can impact cancer biology. Both human and animal studies have shown the sympathetic and neuroendocrine responses to psychosocial stress significantly impacts cancer, in part, through regulation of inflammatory mediators. Psychosocial stressors stimulate neuroendocrine, sympathetic, and immune responses that result in the activation of the hypothalamic-pituitary-adrenal (HPA)-axis, sympathetic nervous system (SNS), and the subsequent regulation of inflammatory responses by immune cells. Social disruption (SDR) stress, a murine model of psychosocial stress and repeated social defeat, provides a novel and powerful tool to probe the mechanisms leading to stress-induced alterations in inflammation, tumor growth, progression, and metastasis. In this review, we will focus on SDR as an important model of psychosocial stress in understanding neural-immune mechanisms in cancer.

The evolutionary significance of depression in Pathogen Host Defense (PATHOS-D)

Given the manifold ways that depression impairs Darwinian fitness, the persistence in the human genome of risk alleles for the disorder remains a much debated mystery. Evolutionary theories that view depressive symptoms as adaptive fail to provide parsimonious explanations for why even mild depressive symptoms impair fitness-relevant social functioning, whereas theories that suggest that depression is maladaptive fail to account for the high prevalence of depression risk alleles in human populations. These limitations warrant novel explanations for the origin and persistence of depression risk alleles. Accordingly, studies on risk alleles for depression were identified using PubMed and Ovid MEDLINE to examine data supporting the hypothesis that risk alleles for depression originated and have been retained in the human genome because these alleles promote pathogen host defense, which includes an integrated suite of immunological and behavioral responses to infection. Depression risk alleles identified by both candidate gene and genome-wide association study (GWAS) methodologies were found to be regularly associated with immune responses to infection that were likely to enhance survival in the ancestral environment. Moreover, data support the role of specific depressive symptoms in pathogen host defense including hyperthermia, reduced bodily iron stores, conservation/withdrawal behavior, hypervigilance and anorexia. By shifting the adaptive context of depression risk alleles from relations with conspecifics to relations with the microbial world, the Pathogen Host Defense (PATHOS-D) hypothesis provides a novel explanation for how depression can be nonadaptive in the social realm, whereas its risk alleles are nonetheless represented at prevalence rates that bespeak an adaptive function.

β-Adrenergic receptor mediated increases in activation and function of natural killer cells following repeated social disruption

Natural killer (NK) cells are specialized innate lymphocytes important in the early defense against tumor and virus bearing cells. Many factors influence the immune system's effectiveness against pathogens, including stress. Social disruption (SDR) "primes" macrophages/monocytes and dendritic cells thereby enhancing their anti-microbial function. What remains unclear is whether similar responses are evident in NK cells. Current studies investigated the cellular distribution and activation/inhibitory phenotypes of NK cells in the spleen, lung, and blood of C57BL/6 male mice following SDR. Furthermore, cytolytic activity and anti-viral cytokine production of splenic NK cells were determined. Lastly, β-adrenergic receptor (β-AR) signaling was investigated to determine possible mechanisms behind the SDR-induced NK cell alterations. Results indicated NK cells from SDR mice have increased expression of CD16 and CD69 and reduced NKG2a and Ly49a expression on splenic CD3-/DX5+ NK cells indicative of an activated phenotype, both immediately and 14h post-SDR. Administration of propranolol (10mg/kg; non-selective β-adrenergic receptor antagonist) was shown to block these "priming" effects at the 14h time-point. In the lung, SDR had similar effects on activation and inhibitory receptors 14h post-SDR, however no alterations were evident in the blood besides increased NK cells directly after SDR. Additionally, splenic NK cells from SDR mice had increased CD107a surface expression, cytolytic activity, and IFN-γ production was increased upon costimulation with IgG and IL-2 ex vivo. Collectively, these data suggest that social stress "primes" NK cells in the spleen and lung to be more proficient in their cytolytic and anti-viral/tumor effecter functions through β-adrenergic receptor dependent signaling.

Stress and the anti-influenza immune response: repeated social defeat augments clonal expansion of CD8(+)T cells during primary influenza A viral infection

Social disruption stress (SDR) prior to primary influenza A virus (IAV) infection augments memory to IAV re-challenge in a T cell-specific manner. However, the effect of SDR on the primary anti-viral immune response has not been elucidated. In this study, SDR-infected (INF) mice terminated viral gene expression earlier and mounted an enhanced pulmonary IAV-specific CD8(+)T cell response versus controls. Additionally, SDR-INF mice had a more pro-inflammatory lung profile prior to and during infection and an attenuated corticosterone response. These data demonstrate neuroendocrine modification of the lung microenvironment and increased antigen-specific T cell activation, clonal expansion and viral control in stress-exposed mice.

Social disruption induced priming of CNS inflammatory response to Theiler's virus is dependent upon stress induced IL-6 release

Chronic social disruption stress (SDR) exacerbates acute and chronic phase Theiler's murine encephalomyelitis virus (TMEV) infection, a mouse model of multiple sclerosis. However, the precise mechanism by which this occurs remains unknown. The present study suggests that SDR exacerbates TMEV disease course by priming virus-induced neuroinflammation. It was demonstrated that IL-1β mRNA expression increases following acute SDR; however, IL-6 mRNA expression, but not IL-1β, is upregulated in response to chronic SDR. Furthermore, this study demonstrated SDR prior to infection increases infection related central IL-6 and IL-1β mRNA expression, and administration of IL-6 neutralizing antibody during SDR reverses this increase in neuroinflammation.

Direct association between pharyngeal viral secretion and host cytokine response in severe pandemic influenza

BACKGROUND

Severe disease caused by 2009 pandemic influenza A/H1N1virus is characterized by the presence of hypercytokinemia. The origin of the exacerbated cytokine response is unclear. As observed previously, uncontrolled influenza virus replication could strongly influence cytokine production. The objective of the present study was to evaluate the relationship between host cytokine responses and viral levels in pandemic influenza critically ill patients.

METHODS

Twenty three patients admitted to the ICU with primary viral pneumonia were included in this study. A quantitative PCR based method targeting the M1 influenza gene was developed to quantify pharyngeal viral load. In addition, by using a multiplex based assay, we systematically evaluated host cytokine responses to the viral infection at admission to the ICU. Correlation studies between cytokine levels and viral load were done by calculating the Spearman correlation coefficient.

RESULTS

Fifteen patients needed of intubation and ventilation, while eight did not need of mechanical ventilation during ICU hospitalization. Viral load in pharyngeal swabs was 300 fold higher in the group of patients with the worst respiratory condition at admission to the ICU. Pharyngeal viral load directly correlated with plasma levels of the pro-inflammatory cytokines IL-6, IL-12p70, IFN-γ, the chemotactic factors MIP-1β, GM-CSF, the angiogenic mediator VEGF and also of the immuno-modulatory cytokine IL-1ra (p < 0.05). Correlation studies demonstrated also the existence of a significant positive association between the levels of these mediators, evidencing that they are simultaneously regulated in response to the virus.

CONCLUSIONS

Severe respiratory disease caused by the 2009 pandemic influenza virus is characterized by the existence of a direct association between viral replication and host cytokine response, revealing a potential pathogenic link with the severe disease caused by other influenza subtypes such as H5N1.

Reciprocal regulation of the neural and innate immune systems

Innate immune responses are regulated by microorganisms and cell death, as well as by a third class of stress signal from the nervous and endocrine systems. The innate immune system also feeds back, through the production of cytokines, to regulate the function of the central nervous system (CNS), and this has effects on behaviour. These signals provide an extrinsic regulatory circuit that links physiological, social and environmental conditions, as perceived by the CNS, with transcriptional 'decision-making' in leukocytes. CNS-mediated regulation of innate immune responses optimizes total organism fitness and provides new opportunities for therapeutic control of chronic infectious, inflammatory and neuropsychiatric diseases.