Adrenergic inhibition of innate anti-viral response: PKA blockade of Type I interferon gene transcription mediates catecholamine support for HIV-1 replication

Regulation of IFNβ expression: focusing on the role of its promoter and transcription regulators

IFNβ is a single-copy gene without an intron. Under normal circumstances, it shows low or no expression in cells. It is upregulated only when the body needs it or is stimulated. Stimuli bind to the pattern recognition receptors (PRRs) and pass via various signaling pathways to several basic transcriptional regulators, such as IRFs, NF-кB, and AP-1. Subsequently, the transcriptional regulators enter the nucleus and bind to regulatory elements of the IFNβ promoter. After various modifications, the position of the nucleosome is altered and the complex is assembled to activate the IFNβ expression. However, IFNβ regulation involves a complex network. For the study of immunity and diseases, it is important to understand how transcription factors bind to regulatory elements through specific forms, which elements in cells are involved in regulation, what regulation occurs during the assembly of enhancers and transcription complexes, and the possible regulatory mechanisms after transcription. Thus, this review focuses on the various regulatory mechanisms and elements involved in the activation of IFNβ expression. In addition, we discuss the impact of this regulation in biology.

Hold Breath: Autonomic Neural Regulation of Innate Immunity to Defend Against SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel member of the genus of betacoronavirus, which caused a pandemic of coronavirus disease 2019 (COVID-19) worldwide. The innate immune system plays a critical role in eliminating the virus, which induces inflammatory cytokine and chemokine secretion, produces different interferons, and activates the adaptive immune system. Interactions between the autonomic nervous system and innate immunity release neurotransmitters or neuropeptides to balance the excess secretion of inflammatory cytokines, control the inflammation, and restore the host homeostasis. However, more neuro-immune mechanisms to defend against viral infection should be elucidated. Here, we mainly review and provide our understanding and viewpoint on the interaction between respiratory viral proteins and host cell receptors, innate immune responses to respiratory viral infection, and the autonomic neural regulation of the innate immune system to control respiratory viruses caused by lungs and airways inflammation.

Sympathetic Nerves and Innate Immune System in the Spleen: Implications of Impairment in HIV-1 and Relevant Models

The immune and sympathetic nervous systems are major targets of human, murine and simian immunodeficiency viruses (HIV-1, MAIDS, and SIV, respectively). The spleen is a major reservoir for these retroviruses, providing a sanctuary for persistent infection of myeloid cells in the white and red pulps. This is despite the fact that circulating HIV-1 levels remain undetectable in infected patients receiving combined antiretroviral therapy. These viruses sequester in immune organs, preventing effective cures. The spleen remains understudied in its role in HIV-1 pathogenesis, despite it hosting a quarter of the body’s lymphocytes and diverse macrophage populations targeted by HIV-1. HIV-1 infection reduces the white pulp, and induces perivascular hyalinization, vascular dysfunction, tissue infarction, and chronic inflammation characterized by activated epithelial-like macrophages. LP-BM5, the retrovirus that induces MAIDS, is a well-established model of AIDS. Immune pathology in MAIDs is similar to SIV and HIV-1 infection. As in SIV and HIV, MAIDS markedly changes splenic architecture, and causes sympathetic dysfunction, contributing to inflammation and immune dysfunction. In MAIDs, SIV, and HIV, the viruses commandeer splenic macrophages for their replication, and shift macrophages to an M2 phenotype. Additionally, in plasmacytoid dendritic cells, HIV-1 blocks sympathetic augmentation of interferon-β (IFN-β) transcription, which promotes viral replication. Here, we review viral–sympathetic interactions in innate immunity and pathophysiology in the spleen in HIV-1 and relevant models. The situation remains that research in this area is still sparse and original hypotheses proposed largely remain unanswered.

Stress and cancer: mechanisms, significance and future directions

The notion that stress and cancer are interlinked has dominated lay discourse for decades. More recent animal studies indicate that stress can substantially facilitate cancer progression through modulating most hallmarks of cancer, and molecular and systemic mechanisms mediating these effects have been elucidated. However, available clinical evidence for such deleterious effects is inconsistent, as epidemiological and stress-reducing clinical interventions have yielded mixed effects on cancer mortality. In this Review, we describe and discuss specific mediating mechanisms identified by preclinical research, and parallel clinical findings. We explain the discrepancy between preclinical and clinical outcomes, through pointing to experimental strengths leveraged by animal studies and through discussing methodological and conceptual obstacles that prevent clinical studies from reflecting the impacts of stress. We suggest approaches to circumvent such obstacles, based on targeting critical phases of cancer progression that are more likely to be stress-sensitive; pharmacologically limiting adrenergic-inflammatory responses triggered by medical procedures; and focusing on more vulnerable populations, employing personalized pharmacological and psychosocial approaches. Recent clinical trials support our hypothesis that psychological and/or pharmacological inhibition of excess adrenergic and/or inflammatory stress signalling, especially alongside cancer treatments, could save lives.

Role of sleep deprivation in immune-related disease risk and outcomes

Modern societies are experiencing an increasing trend of reduced sleep duration, with nocturnal sleeping time below the recommended ranges for health. Epidemiological and laboratory studies have demonstrated detrimental effects of sleep deprivation on health. Sleep exerts an immune-supportive function, promoting host defense against infection and inflammatory insults. Sleep deprivation has been associated with alterations of innate and adaptive immune parameters, leading to a chronic inflammatory state and an increased risk for infectious/inflammatory pathologies, including cardiometabolic, neoplastic, autoimmune and neurodegenerative diseases. Here, we review recent advancements on the immune responses to sleep deprivation as evidenced by experimental and epidemiological studies, the pathophysiology, and the role for the sleep deprivation-induced immune changes in increasing the risk for chronic diseases. Gaps in knowledge and methodological pitfalls still remain. Further understanding of the causal relationship between sleep deprivation and immune deregulation would help to identify individuals at risk for disease and to prevent adverse health outcomes.

Parasympathetic neural activity and the reciprocal regulation of innate antiviral and inflammatory genes in the human immune system

The vagus nerve mediates parasympathetic nervous system control of peripheral physiological processes including cardiovascular activity and immune response. In mice, tonic vagal activation down-regulates inflammation via nicotinic acetylcholine receptor-mediated inhibition of the pro-inflammatory transcription factor NF-κB in monocyte/macrophages. Because Type I interferon and pro-inflammatory genes are regulated reciprocally at the level of transcription factor activation and cell differentiation, we hypothesized that vagal activity would up-regulate Type I interferon response genes concurrently with inflammatory downregulation in human immune cells. We mapped empirical individual differences in the circulating leukocyte transcriptome and vagal activity indexed by high frequency (0.15-0.40 Hz) heart rate variability (HF-HRV) in 380 participants in the Midlife in the US study. Here we show that promoter-based bioinformatics analyses linked greater HF-HRV to reduced NF-κB activity and increased activity of IRF transcription factors involved in Type I interferon response (independent of β-antagonists, BMI, smoking, heavy alcohol consumption, and demographic factors). Transcript origin analyses implicated myeloid lineage immune cells as targets, representing per-cell alterations in gene transcription as HF-HRV was not associated with differential prevalence of leukocyte subsets. These findings support the concept of parasympathetic inhibition of pro-inflammatory gene expression in humans and up-regulation of Type I interferons that could augment host defense against viral infections.

Resting parasympathetic nervous system activity is associated with greater antiviral gene expression

Parasympathetic nervous system activity can downregulate inflammation, but it remains unclear how parasympathetic nervous system activity relates to antiviral activity. The present study examined associations between parasympathetic nervous system activity and cellular antiviral gene regulation in 90 adolescents (M_age = 16.28, SD = 0.73; 51.1% female) who provided blood samples and measures of cardiac respiratory sinus arrhythmia (RSA), twice, five weeks apart. Using a multilevel analytic framework, we found that higher RSA (an indicator of higher parasympathetic nervous system activity)-both at rest and during paced breathing-was associated with higher expression of Type I interferon (IFN) response genes in circulating leukocytes, even after adjusting for demographic and biological covariates. RSA was not associated with a parallel measure of inflammatory gene expression. These results identify a previously unrecognized immunoregulatory aspect of autonomic nervous system function and highlight a potential biological pathway by which parasympathetic nervous system activity may relate to health.

A biopsychosocial framework for understanding sexual and gender minority health: A call for action

The number of US adults identifying as lesbian, gay, bisexual, transgender, or a different sexual identity has doubled since 2008, and about 40 % of the sexual and gender minority population identify as people of color. Minority stress theory posits that sexual and gender minorities are at particular risk for stress via stigma and discrimination at the structural, interpersonal, and individual levels. This stress, in turn, elevates the risk of adverse health outcomes across several domains. However, there remains a conspicuously limited amount of research on the psychoneuroimmunology of stress among sexual and gender minorities. We developed the Biopsychosocial Minority Stress Framework which posits that sexual minority status leads to unique experiences of minority stress which results in adverse health behavioral factors, elevated psychological distress and sleep disturbance, and immune dysregulation. Moderators in the model include both individual differences and intersectional identities. There is a crucial need to understand the biological-psychological axis of stress among the increasingly visible sexual and gender minority population to increase their health, longevity, and quality of life.

Mechanisms Supporting the Use of Beta-Blockers for the Management of Breast Cancer Bone Metastasis

Simple Summary

Bone represents the most common site of metastasis for breast cancer and the establishment and growth of metastatic cancer cells within the skeleton significantly reduces the quality of life of patients and their survival. The interplay between sympathetic nerves and bone cells, and its influence on the process of breast cancer bone metastasis is increasingly being recognized. Several mechanisms, all dependent on β-adrenergic receptor signaling in stromal bone cells, were shown to promote the establishment of disseminated cancer cells into the skeleton. This review provides a summary of these mechanisms in support of the therapeutic potential of β-blockers for the early management of breast cancer metastasis.

Abstract

The skeleton is heavily innervated by sympathetic nerves and represents a common site for breast cancer metastases, the latter being the main cause of morbidity and mortality in breast cancer patients. Progression and recurrence of breast cancer, as well as decreased overall survival in breast cancer patients, are associated with chronic stress, a condition known to stimulate sympathetic nerve outflow. Preclinical studies have demonstrated that sympathetic stimulation of β-adrenergic receptors in osteoblasts increases bone vascular density, adhesion of metastatic cancer cells to blood vessels, and their colonization of the bone microenvironment, whereas β-blockade prevented these events in mice with high endogenous sympathetic activity. These findings in preclinical models, along with clinical data from breast cancer patients receiving β-blockers, support the pathophysiological role of excess sympathetic nervous system activity in the formation of bone metastases, and the potential of commonly used, safe, and low-cost β-blockers as adjuvant therapy to improve the prognosis of bone metastases.

Neural Regulation of Interactions Between Group 2 Innate Lymphoid Cells and Pulmonary Immune Cells

Emerging evidence supports the involvement of nervous system in the regulation of immune responses. Group 2 innate lymphoid cells (ILC2), which function as a crucial bridge between innate and adaptive immunity, are present in large numbers in barrier tissues. Neuropeptides and neurotransmitters have been found to participate in the regulation of ILC2, adding a new dimension to neuroimmunity. However, a comprehensive and detailed overview of the mechanisms of neural regulation of ILC2, associated with previous findings and prospects for future research, is still lacking. In this review, we compile existing information that supports neurons as yet poorly understood regulators of ILC2 in the field of lung innate and adaptive immunity, focusing on neural regulation of the interaction between ILC2 and pulmonary immune cells.

Isolation, social stress, low socioeconomic status and its relationship to immune response in Covid-19 pandemic context

The coronavirus disease 2019 (COVID-19) outbreak was first reported December 2019, in Wuhan, China, and has since spread worldwide. Social distancing or isolation measures were taken to mitigate the pandemic. Furthermore, stress and low socioeconomic status in humans confer increased vulnerability to morbidity and mortality, what can be biologically observed. This condition tends to remain during the Covid-19 pandemic. Social disruption stress (SDR) raises important questions regarding the functioning of the immune system, and the release of several stress hormones. A molecular pattern, conserved transcriptional response to adversity (CTRA), is thought to have evolved to defend against physical injury during periods of heightened risk. Chronic CTRA activation could leave an organism vulnerable to viral infections, leading to increased pro-inflammatory gene expression and a suppression of anti-viral gene expression. The activation of such transcriptional status is related to conditions of social stress through either hostile human contact, or increased predatory vulnerability due to separation from the social group and also low socioeconomic status. This review aims to point out questions for government officials, researchers and health professionals to better target their actions during a pandemic and encourage studies for a better understanding of these characteristics.

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The coronavirus disease 2019 (COVID-19) outbreak has spread worldwide.

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Community mitigation guidelines, such as social distancing were taken.

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Social disruption stress leads to immune response alterations, and stress hormones.

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CTRA activation may lead to vulnerable to viral infection and systemic inflammation.

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CTRA may be activated due to social isolation and socioeconomic status.

Serious infection may systemically increase noradrenergic signaling and produce psychological effects

Serious infection elicits inflammatory processes that act through a range of molecular pathways, including cytokine signaling. It is not established however that noradrenaline (NA), a widely distributed neurotransmitter in the brain that is also a principal output molecule of the sympathetic nervous system, can produce psychological effects associated with infection. This paper puts forth the hypothesis that through neural-immune crosstalk, serious infection increases noradrenergic signaling, both in the central nervous system and in peripheral organs. In this manner, elevated noradrenergic transmission may help produce basic symptoms of infection such as fever, fatigue, aches and pains (including headache), nausea, and loss of appetite. NA may also promote cognitive impairment, major depression, unipolar mania, and even epileptic seizures in some cases. The paper focuses on three major types of infection: influenza (viral), tuberculosis (bacterial), malaria (parasitic), while also summarizing the potential relationship between NA and human immunodeficiency virus (HIV) infection. Four lines of evidence are used to test association between NA and influenza, tuberculosis, and malaria: direct measures of NA and its metabolites; and incidence of hypertension, bipolar mania, and epileptic seizures, since the latter three conditions may be associated with elevated NA. In addition, heart rate variability data are examined with respect to a number of infectious diseases, since those data provide information on sympathetic nervous system activity. While the data do not unequivocally support elevated noradrenergic signaling promoting psychological symptomatology with infection, many studies are consistent with this view.

Implication of Spiritual Network Support System in Epigenomic Modulation and Health Trajectory

With challenges in understanding the multifactorial etiologies of disease and individual treatment effect heterogeneities over the past four decades, much has been acquired on how physical, chemical and social environments affect human health, predisposing certain subpopulations to adverse health outcomes, especially the socio-environmentally disadvantaged (SED). Current translational data on gene and adverse environment interaction have revealed how adverse gene-environment interaction, termed aberrant epigenomic modulation, translates into impaired gene expression via messenger ribonucleic acid (mRNA) dysregulation, reflecting abnormal protein synthesis and hence dysfunctional cellular differentiation and maturation. The environmental influence on gene expression observed in most literature includes physical, chemical, physicochemical and recently social environment. However, data are limited on spiritual or religious environment network support systems, which reflect human psychosocial conditions and gene interaction. With this limited information, we aimed to examine the available data on spiritual activities characterized by prayers and meditation for a possible explanation of the nexus between the spiritual network support system (SNSS) as a component of psychosocial conditions, implicated in social signal transduction, and the gene expression correlate. With the intent to incorporate SNSS in human psychosocial conditions, we assessed the available data on bereavement, loss of spouse, loneliness, social isolation, low socio-economic status (SES), chronic stress, low social status, social adversity (SA) and early life stress (ELS), as surrogates for spiritual support network connectome. Adverse human psychosocial conditions have the tendency for impaired gene expression through an up-regulated conserved transcriptional response to adversity (CTRA) gene expression via social signal transduction, involving the sympathetic nervous system (SNS), beta-adrenergic receptors, the hypothalamus-pituitary-adrenal (HPA) axis and the glucocorticoid response. This review specifically explored CTRA gene expression and the nuclear receptor subfamily 3 group C member 1 (NR3C1) gene, a glucocorticoid receptor gene, in response to stress and the impaired negative feedback, given allostatic overload as a result of prolonged and sustained stress and social isolation as well as the implied social interaction associated with religiosity. While more remains to be investigated on psychosocial and immune cell response and gene expression, current data on human models do implicate appropriate gene expression via the CTRA and NR3C1 gene in the SNSS as observed in meditation, yoga and thai-chi, implicated in malignant neoplasm remission. However, prospective epigenomic studies in this context are required in the disease causal pathway, prognosis and survival, as well as cautious optimism in the application of these findings in clinical and public health settings, due to unmeasured and potential confoundings implicated in these correlations.

Experienced discrimination and racial differences in leukocyte gene expression

Racial disparities in health outcomes between African Americans and European Americans have been well-documented, but not fully understood. Chronic inflammation contributes to several of the diseases showing racial disparities (e.g., Human Immunodeficiency Virus [HIV]), and racial differences in stress exposure (e.g., experiences of racial discrimination) that stimulate pro-inflammatory processes that may contribute to differential health outcomes. We performed a cross-sectional bioinformatic analyses relating perceived discrimination (as measured by the Perceived Ethnic Discrimination Questionnaire [PED-Q]) to the activity of pro-inflammatory, neuroendocrine, and antiviral transcription control pathways relevant to the conserved transcriptional response to adversity (CTRA) in peripheral blood leukocytes. Subjects were 71 individuals (37 HIV-seropositive (HIV+); 34 HIV-seronegative (HIV-)) (mean age = 53 years, range 27-63), who self-identified either as African American/Black (n = 48) or European American/White (n = 23). This provided the opportunity to examine the independent effects of race and HIV, as well as the modifying role of perceived discrimination on pathways involved in CTRA. Exploratory analysis examined the interactive effects of HIV and race on pathways involved in CTRA. Relative to European Americans, African Americans showed increased activity of two key pro-inflammatory transcription control pathways (NF- кB and AP-1) and two stress-responsive signaling pathways (CREB and glucocorticoid receptor); these effects did not differ significantly as a function of HIV infection (HIV x Race interaction, all p > .10). Results suggested that differences in experiences of racial discrimination could potentially account for more than 50% of the total race-related difference in pro-inflammatory transcription factor activity. In sum, differential exposure to racial discrimination may contribute to racial disparities in health outcomes in part by activating threat-related molecular programs that stimulate inflammation and contribute to increased risk of chronic illnesses.

Interplay Between the Gut-Brain Axis, Obesity and Cognitive Function

Obesity continues to be one of the major public health problems due to its high prevalence and co-morbidities. Common co-morbidities not only include cardiometabolic disorders but also mood and cognitive disorders. Obese subjects often show deficits in memory, learning and executive functions compared to normal weight subjects. Epidemiological studies also indicate that obesity is associated with a higher risk of developing depression and anxiety, and vice versa. These associations between pathologies that presumably have different etiologies suggest shared pathological mechanisms. Gut microbiota is a mediating factor between the environmental pressures (e.g., diet, lifestyle) and host physiology, and its alteration could partly explain the cross-link between those pathologies. Westernized dietary patterns are known to be a major cause of the obesity epidemic, which also promotes a dysbiotic drift in the gut microbiota; this, in turn, seems to contribute to obesity-related complications. Experimental studies in animal models and, to a lesser extent, in humans suggest that the obesity-associated microbiota may contribute to the endocrine, neurochemical and inflammatory alterations underlying obesity and its comorbidities. These include dysregulation of the HPA-axis with overproduction of glucocorticoids, alterations in levels of neuroactive metabolites (e.g., neurotransmitters, short-chain fatty acids) and activation of a pro-inflammatory milieu that can cause neuro-inflammation. This review updates current knowledge about the role and mode of action of the gut microbiota in the cross-link between energy metabolism, mood and cognitive function.

Sleep Health: Reciprocal Regulation of Sleep and Innate Immunity

Sleep disturbances including insomnia independently contribute to risk of inflammatory disorders and major depressive disorder. This review and overview provides an integrated understanding of the reciprocal relationships between sleep and the innate immune system and considers the role of sleep in the nocturnal regulation of the inflammatory biology dynamics; the impact of insomnia complaints, extremes of sleep duration, and experimental sleep deprivation on genomic, cellular, and systemic markers of inflammation; and the influence of sleep complaints and insomnia on inflammaging and molecular processes of cellular aging. Clinical implications of this research include discussion of the contribution of sleep disturbance to depression and especially inflammation-related depressive symptoms. Reciprocal action of inflammatory mediators on the homeostatic regulation of sleep continuity and sleep macrostructure, and the potential of interventions that target insomnia to reverse inflammation, are also reviewed. Together, interactions between sleep and inflammatory biology mechanisms underscore the implications of sleep disturbance for inflammatory disease risk, and provide a map to guide the development of treatments that modulate inflammation, improve sleep, and promote sleep health.

Neuroimmune interactions: dendritic cell modulation by the sympathetic nervous system

Dendritic cells are of paramount importance bridging innate and adaptive immune responses. Depending on the context, after sensing environmental antigens, commensal microorganisms, pathogenic agents, or antigens from the diet, dendritic cells may drive either different effector adaptive immune responses or tolerance, avoiding tissue damage. Although the plasticity of the immune response and the capacity to regulate itself are considered essential to orchestrate appropriate physiological responses, it is known that the nervous system plays a relevant role controlling immune cell function. Dendritic cells present in the skin, the intestine, and lymphoid organs, besides expressing adrenergic receptors, can be reached by neurotransmitters released by sympathetic fibers innervating these tissues. These review focus on how neurotransmitters from the sympathetic nervous system can modulate dendritic cell function and how this may impact the immune response and immune-mediated disorders.

Inhibition of catecholamine degradation ameliorates while chemical sympathectomy aggravates the severity of acute Friend retrovirus infection in mice

Several lines of evidence indicate that the sympathetic nervous system (SNS) might be involved in the pathogenesis and progression of retroviral infections. However, experimental data are scarce and findings inconsistent. Here, we investigated the role of the SNS during acute infection with Friend virus (FV), a pathogenic murine retrovirus that causes polyclonal proliferation of erythroid precursor cells and splenomegaly in adult mice. Experimental animals were infected with FV complex, and viral load, spleen weight, and splenic noradrenaline (NA) concentration was analyzed until 25 days post infection. Results show that FV infection caused a massive but transient depletion in splenic NA during the acute phase of the disease. At the peak of the virus-induced splenomegaly, splenic NA concentration was reduced by about 90% compared to naïve uninfected mice. Concurrently, expression of the catecholamine degrading enzymes monoamine oxidase A (MAO-A) and catechol-O-methyltransferase (COMT) was significantly upregulated in immune cells of the spleen. Pharmacological inhibition of MAO-A and COMT by the selective inhibitors clorgyline and 3,5-dinitrocatechol, respectively, efficiently blocked NA degradation and significantly reduced viral load and virus-induced splenomegaly. In contrast, chemical sympathectomy prior to FV inoculation aggravated the acute infection and extended the duration of the disease. Together these findings demonstrate that catecholamine availability at the site of viral replication is an important factor affecting the course of retroviral infections.

Social instability and immunity in rhesus monkeys: the role of the sympathetic nervous system

Social instability can adversely affect endocrine, immune and health outcomes, and recent evidence suggests that the sympathetic nervous system (SNS) might mediate these effects. We conducted two studies with adult male rhesus monkeys (Macaca mulatta) to understand how social conditions affect measures of SNS activity and immune function. In Experiment 1, animals were socialized in stable social conditions, then were switched to unstable (stressful) social conditions, then were returned to stable conditions. Analysis revealed quadratic effects for measures of behaviour, urinary metabolites of epinephrine and norepinephrine, and expression of immune response genes: as expected, social instability adversely impacted most measures, and the effects remediated upon re-imposition of stable conditions. Cortisol levels were unaffected. In Experiment 2, we used the sympathomimetic drug methamphetamine to challenge the SNS; animals also underwent socialization in stable or unstable groups. Surprisingly, while methamphetamine elevated plasma catecholamines, responses in lymph nodes tracked the social, and not the drug, condition: social instability upregulated the density of SNS fibres in lymph nodes and downregulated Type I interferon gene expression. Together, these results indicate that the SNS is extremely sensitive to social conditions; full understanding of the adverse effects of social instability on health should therefore incorporate measures of this health-relevant system.

Myeloid differentiation architecture of leukocyte transcriptome dynamics in perceived social isolation

To define the cellular mechanisms of up-regulated inflammatory gene expression and down-regulated antiviral response in people experiencing perceived social isolation (loneliness), we conducted integrative analyses of leukocyte gene regulation in humans and rhesus macaques. Five longitudinal leukocyte transcriptome surveys in 141 older adults showed up-regulation of the sympathetic nervous system (SNS), monocyte population expansion, and up-regulation of the leukocyte conserved transcriptional response to adversity (CTRA). Mechanistic analyses in a macaque model of perceived social isolation confirmed CTRA activation and identified selective up-regulation of the CD14(++)/CD16(-) classical monocyte transcriptome, functional glucocorticoid desensitization, down-regulation of Type I and II interferons, and impaired response to infection by simian immunodeficiency virus (SIV). These analyses identify neuroendocrine-related alterations in myeloid cell population dynamics as a key mediator of CTRA transcriptome skewing, which may both propagate perceived social isolation and contribute to its associated health risks.

Sympathetic nervous system regulation of the tumour microenvironment

The peripheral autonomic nervous system (ANS) is known to regulate gene expression in primary tumours and their surrounding microenvironment. Activation of the sympathetic division of the ANS in particular modulates gene expression programmes that promote metastasis of solid tumours by stimulating macrophage infiltration, inflammation, angiogenesis, epithelial-mesenchymal transition and tumour invasion, and by inhibiting cellular immune responses and programmed cell death. Haematological cancers are modulated by sympathetic nervous system (SNS) regulation of stem cell biology and haematopoietic differentiation programmes. In addition to identifying a molecular basis for physiologic stress effects on cancer, these findings have also identified new pharmacological strategies to inhibit cancer progression in vivo.

Psychosocial and Neurohormonal Predictors of HIV Disease Progression (CD4 Cells and Viral Load): A 4 Year Prospective Study

Most studies of psychosocial predictors of disease progression in HIV have not considered norepinephrine (NE), a neurohormone related to emotion and stress, even though NE has been related to accelerated viral replication in vitro and impaired response to antiretroviral therapy (ART). We therefore examined NE, cortisol, depression, hopelessness, coping, and life event stress as predictors of HIV progression in a diverse sample. Participants (n = 177) completed psychological assessment, blood draws [CD4, viral load (VL)], and a 15 h urine sample (NE, cortisol) every 6 months over 4 years. Hierarchical linear modeling (HLM) was used to model slope in CD4 and VL controlling for ART at every time point, gender, age, race, SES, and initial disease status. NE (as well as depression, hopelessness, and avoidant coping) significantly predicted a greater rate of decrease in CD4 and increase in VL. Cortisol was not significantly related to CD4, but predicted VL increase. To our knowledge, this is the first study relating NE, in vivo, to accelerated disease progression over an extended time. It also extends our previous 2 year study by relating depressed mood and coping to accelerated disease progression over 4 years.

Human social genomics

A growing literature in human social genomics has begun to analyze how everyday life circumstances influence human gene expression. Social-environmental conditions such as urbanity, low socioeconomic status, social isolation, social threat, and low or unstable social status have been found to associate with differential expression of hundreds of gene transcripts in leukocytes and diseased tissues such as metastatic cancers. In leukocytes, diverse types of social adversity evoke a common conserved transcriptional response to adversity (CTRA) characterized by increased expression of proinflammatory genes and decreased expression of genes involved in innate antiviral responses and antibody synthesis. Mechanistic analyses have mapped the neural "social signal transduction" pathways that stimulate CTRA gene expression in response to social threat and may contribute to social gradients in health. Research has also begun to analyze the functional genomics of optimal health and thriving. Two emerging opportunities now stand to revolutionize our understanding of the everyday life of the human genome: network genomics analyses examining how systems-level capabilities emerge from groups of individual socially sensitive genomes and near-real-time transcriptional biofeedback to empirically optimize individual well-being in the context of the unique genetic, geographic, historical, developmental, and social contexts that jointly shape the transcriptional realization of our innate human genomic potential for thriving.

Oral intake of heat-killed Lactobacillus plantarum L-137 decreases the incidence of upper respiratory tract infection in healthy subjects with high levels of psychological stress

The immunomodulatory effects of live or non-viable lactic acid bacteria have been extensively investigated. We reported that oral intake of heat-killed Lactobacillus plantarum L-137 (HK L-137) augmented innate and acquired immunity in mice and human subjects. To examine the effects of HK L-137 intake on upper respiratory tract infection (URTI) symptoms and immune functions in human subjects, a randomised, double-blind, placebo-controlled, parallel study was conducted in subjects with high psychological stress levels. A total of seventy-eight healthy subjects (thirty-three men and forty-five women; mean age 50·6 years) with scores of >41 on eighteen-item subscales of psychological distress in the Brief Job Stress Questionnaire were randomly assigned to receive a tablet containing HK L-137 (10 mg) or a placebo tablet daily for 12 weeks. The URTI symptoms were rated once daily on the validated twenty-one-item Wisconsin Upper Respiratory Symptom Survey-21. Immune functions, such as concanavalin A-induced proliferation and percentages of interferon (IFN)-γ- and IL-4-producing CD4 T cells of peripheral blood mononuclear cells (PBMC), and serum IFN-β concentrations were measured every 4 weeks. URTI incidence was significantly lower in the HK L-137 group than in the control group. URTI incidence, duration and severity, and duration of medication showed significant negative correlations with duration of HK L-137 intake. The percentage change from baseline of concanavalin A-induced proliferation of PBMC was significantly greater in the HK L-137 group than in the control group. These findings suggest that daily HK L-137 intake can decrease URTI incidence in healthy subjects, possibly through augmentation of immune functions.

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.

Social regulation of human gene expression: mechanisms and implications for public health

Recent analyses have discovered broad alterations in the expression of human genes across different social environments. The emerging field of social genomics has begun to identify the types of genes sensitive to social regulation, the biological signaling pathways mediating these effects, and the genetic polymorphisms that modify their individual impact. The human genome appears to have evolved specific "social programs" to adapt molecular physiology to the changing patterns of threat and opportunity ancestrally associated with changing social conditions. In the context of the immune system, this programming now fosters many of the diseases that dominate public health. The embedding of individual genomes within a broader metagenomic network provides a framework for integrating molecular, physiologic, and social perspectives on human health.

Beta2-adrenoceptor stimulation suppresses TLR9-dependent IFNA1 secretion in human peripheral blood mononuclear cells

Introduction

IFNA1 (interferon alpha) is a key cytokine regulating the activity of numerous immune cells. Plasmacytoid dendritic cells (pDCs) as natural interferon-producing cells play critical roles as sensors of pathogens and link innate to adaptive immunity. CpG motifs within DNA sequences activating toll-like receptor 9 (TLR9) are the main stimuli eliciting IFNA1 secretion from pDCs. Adrenergic substances are capable of differentially modulating the response from various immune cells. Hence, the aim of this study was to examine how adrenoceptor stimulation influences TLR9-induced IFNA1 secretion from human pDCs.

Methods

PBMCs generated from human whole blood and pDCs enriched from buffy coats were stimulated with LPS and CpG-ODN 2336 in the presence or absence of epinephrine and different adrenoceptor antagonists. Secretion of TNF and IFNA1 was measured by ELISA. Flow cytometry was used to determine efficacy of pDC enrichment and adrenoceptor expression of PBMC subsets. The influence of modified IFNA1 secretion on NK cell activity was evaluated using a colorimetric tumor cell lysis assay.

Results

TLR9-induced IFNA1 secretion as well as TLR4-induced TNF secretion from PBMCs was dose-dependently attenuated by coincubation with epinephrine. Combination with different specific adrenoceptor antagonists revealed that this effect was mediated by the adrenoceptor β₂ (ADRB2). Since flow cytometric analysis could exclude the presence of ADRB2 on pDCs, highly enriched pDCs lacked any visible impact of adrenoceptor stimulation on TLR9-induced IFNA1 release. Combination of pDCs with PBMCs restored the effect, even when they were separated by a permeable membrane. Suppression of TLR9-mediated IFNA1 secretion from PBMCs by adrenoceptor stimulation reduced the lytic activity of NK cells on K562 tumor cells.

Conclusion

We provide insights into the underlying mechanisms of the interrelation between immune responses and pharmacological agents widely used in clinical practice. Our results have implications for the future treatment of human patients, in which the endogenous immune response plays a pivotal role, such as during viral infections, inflammatory diseases and cancers.

The Emerging Field of Human Social Genomics

Although we generally experience our bodies as being biologically stable across time and situations, an emerging field of research is demonstrating that external social conditions, especially our subjective perceptions of those conditions, can influence our most basic internal biological processes-namely, the expression of our genes. This research on human social genomics has begun to identify the types of genes that are subject to social-environmental regulation, the neural and molecular mechanisms that mediate the effects of social processes on gene expression, and the genetic polymorphisms that moderate individual differences in genomic sensitivity to social context. The molecular models resulting from this research provide new opportunities for understanding how social and genetic factors interact to shape complex behavioral phenotypes and susceptibility to disease. This research also sheds new light on the evolution of the human genome and challenges the fundamental belief that our molecular makeup is relatively stable and impermeable to social-environmental influence.

Nervous system regulation of the cancer genome

Genomics-based analyses have provided deep insight into the basic biology of cancer and are now clarifying the molecular pathways by which psychological and social factors can regulate tumor cell gene expression and genome evolution. This review summarizes basic and clinical research on neural and endocrine regulation of the cancer genome and its interactions with the surrounding tumor microenvironment, including the specific types of genes subject to neural and endocrine regulation, the signal transduction pathways that mediate such effects, and therapeutic approaches that might be deployed to mitigate their impact. Beta-adrenergic signaling from the sympathetic nervous system has been found to up-regulated a diverse array of genes that contribute to tumor progression and metastasis, whereas glucocorticoid-regulated genes can inhibit DNA repair and promote cancer cell survival and resistance to chemotherapy. Relationships between socio-environmental risk factors, neural and endocrine signaling to the tumor microenvironment, and transcriptional responses by cancer cells and surrounding stromal cells are providing new mechanistic insights into the social epidemiology of cancer, new therapeutic approaches for protecting the health of cancer patients, and new molecular biomarkers for assessing the impact of behavioral and pharmacologic interventions.

Transcriptional modulation of the developing immune system by early life social adversity

To identify molecular mechanisms by which early life social conditions might influence adult risk of disease in rhesus macaques (Macaca mulatta), we analyze changes in basal leukocyte gene expression profiles in 4-mo-old animals reared under adverse social conditions. Compared with the basal condition of maternal rearing (MR), leukocytes from peer-reared (PR) animals and PR animals provided with an inanimate surrogate mother (surrogate/peer reared, SPR) show enhanced expression of genes involved in inflammation, cytokine signaling, and T-lymphocyte activation, and suppression of genes involved in several innate antimicrobial defenses including type I interferon (IFN) antiviral responses. Promoter-based bioinformatic analyses implicate increased activity of CREB and NF-κB transcription factors and decreased activity of IFN response factors (IRFs) in structuring the observed differences in gene expression. Transcript origin analyses identify monocytes and CD4(+) T lymphocytes as primary cellular mediators of transcriptional up-regulation and B lymphocytes as major sources of down-regulated genes. These findings show that adverse social conditions can become embedded within the basal transcriptome of primate immune cells within the first 4 mo of life, and they implicate sympathetic nervous system-linked transcription control pathways as candidate mediators of those effects and potential targets for health-protective intervention.

Viperin restricts chikungunya virus replication and pathology

Chikungunya virus (CHIKV) is a mosquito-borne arthralgia arbovirus that is reemergent in sub-Saharan Africa and Southeast Asia. CHIKV infection has been shown to be self-limiting, but the molecular mechanisms of the innate immune response that control CHIKV replication remain undefined. Here, longitudinal transcriptional analyses of PBMCs from a cohort of CHIKV-infected patients revealed that type I IFNs controlled CHIKV infection via RSAD2 (which encodes viperin), an enigmatic multifunctional IFN-stimulated gene (ISG). Viperin was highly induced in monocytes, the major target cell of CHIKV in blood. Anti-CHIKV functions of viperin were dependent on its localization in the ER, and the N-terminal amphipathic α-helical domain was crucial for its antiviral activity in controlling CHIKV replication. Furthermore, mice lacking Rsad2 had higher viremia and severe joint inflammation compared with wild-type mice. Our data demonstrate that viperin is a critical antiviral host protein that controls CHIKV infection and provide a preclinical basis for the design of effective control strategies against CHIKV and other reemerging arthrogenic alphaviruses.

Cognitive-behavioral stress management reverses anxiety-related leukocyte transcriptional dynamics

BACKGROUND

Chronic threat and anxiety are associated with pro-inflammatory transcriptional profiles in circulating leukocytes, but the causal direction of that relationship has not been established. This study tested whether a cognitive-behavioral stress management (CBSM) intervention targeting negative affect and cognition might counteract anxiety-related transcriptional alterations in people confronting a major medical threat.

METHODS

One hundred ninety-nine women undergoing primary treatment of stage 0-III breast cancer were randomized to a 10-week CBSM protocol or an active control condition. Seventy-nine provided peripheral blood leukocyte samples for genome-wide transcriptional profiling and bioinformatic analyses at baseline, 6-month, and 12-month follow-ups.

RESULTS

Baseline negative affect was associated with >50% differential expression of 201 leukocyte transcripts, including upregulated expression of pro-inflammatory and metastasis-related genes. CBSM altered leukocyte expression of 91 genes by >50% at follow-up (group × time interaction), including downregulation of pro-inflammatory and metastasis-related genes and upregulation of type I interferon response genes. Promoter-based bioinformatic analyses implicated decreased activity of NF-κB/Rel and GATA family transcription factors and increased activity of interferon response factors and the glucocorticoid receptor as potential mediators of CBSM-induced transcriptional alterations.

CONCLUSIONS

In early-stage breast cancer patients, a 10-week CBSM intervention can reverse anxiety-related upregulation of pro-inflammatory gene expression in circulating leukocytes. These findings clarify the molecular signaling pathways by which behavioral interventions can influence physical health and alter peripheral inflammatory processes that may reciprocally affect brain affective and cognitive processes.

Interferon-beta, but not tumor necrosis factor-alpha, production in response to poly I:C is maintained despite exhaustive exercise in mice

It remains unclear whether immune response to viral infection is inhibited by severe exercise. We determined whether exhaustive exercise inhibits interferon (IFN)-β and tumor necrosis factor (TNF)-α production after injection of synthetic double-stranded (ds) RNAs, a polyriboinosinic polyribocytidylic acid (poly I:C), as viral infection model. Male C3H/HeN mice, which were divided into exhaustive-exercised and non-exercised groups, were injected with poly I:C (5 mg/kg). Although TNF-α in response to poly I:C was significantly inhibited by exhaustive exercise, IFN-β was no different in both groups. In in-vitro experiments, catecholamines inhibited poly I:C-induced TNF-α, but not IFN-β, production in macrophages. These results suggest that anti-virus cytokine IFN-β in response to poly I:C might be maintained despite severe stressful exercise.

Molecular pathways: beta-adrenergic signaling in cancer

Beta-adrenergic signaling has been found to regulate multiple cellular processes that contribute to the initiation and progression of cancer, including inflammation, angiogenesis, apoptosis/anoikis, cell motility and trafficking, activation of tumor-associated viruses, DNA damage repair, cellular immune response, and epithelial-mesenchymal transition. In several experimental cancer models, activation of the sympathetic nervous system promotes the metastasis of solid epithelial tumors and the dissemination of hematopoietic malignancies via β-adrenoreceptor-mediated activation of protein kinase A and exchange protein activated by adenylyl cyclase signaling pathways. Within the tumor microenvironment, β-adrenergic receptors on tumor and stromal cells are activated by catecholamines from local sympathetic nerve fibers (norepinephrine) and circulating blood (epinephrine). Tumor-associated macrophages are emerging as key targets of β-adrenergic regulation in several cancer contexts. Sympathetic nervous system regulation of cancer cell biology and the tumor microenvironment has clarified the molecular basis for long-suspected relationships between stress and cancer progression, and now suggests a highly leveraged target for therapeutic intervention. Epidemiologic studies have linked the use of β-blockers to reduced rates of progression for several solid tumors, and preclinical pharmacologic and biomarker studies are now laying the groundwork for translation of β-blockade as a novel adjuvant to existing therapeutic strategies in clinical oncology.

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.

Transcript origin analysis identifies antigen-presenting cells as primary targets of socially regulated gene expression in leukocytes

To clarify the biological rationale for social regulation of gene expression, this study sought to identify the specific immune cell types that are transcriptionally sensitive to subjective social isolation (loneliness). Using reference distributions for the expression of each human gene in each major leukocyte subtype, we mapped the cellular origin of transcripts found to be differentially expressed in the circulating immune cells from chronically lonely individuals. Loneliness-associated genes derived primarily from plasmacytoid dendritic cells, monocytes, and, to a lesser extent, B lymphocytes. Those dynamics reflected per-cell changes in the expression of inducible genes and related more strongly to the subjective experience of loneliness than to objective social network size. Evolutionarily ancient myeloid antigen-presenting cells appear to have evolved a transcriptional sensitivity to socioenvironmental conditions that may allow them to shift basal gene expression profiles to counter the changing microbial threats associated with hostile vs. affine social conditions.

Substance use and HIV disease progression in the HAART era: implications for the primary prevention of HIV

Prior to the era of highly active anti-retroviral therapy (HAART), cohort studies provided equivocal evidence to support the hypothesis that substance use predicts more rapid HIV disease progression. The present review examined the effects of substance use on HIV disease progression in cohort studies with follow-up that continued into the HAART era. Of the 20 studies included in this review, 16 observed that substance use predicted at least one indicator of HIV disease progression. Ten of the 11 studies that followed participants exclusively in the HAART era observed an effect of substance use on HIV disease progression. Findings across studies indicate that stimulant use promotes more rapid HIV disease progression and the effects of substance use on HIV disease progression can persist after controlling for self-reported HAART non-adherence. Future investigations that examine the bio-behavioral pathways whereby substance use promotes HIV disease progression should include: measures of HIV genotypic and phenotypic resistance, multi-method assessment of adherence, and assessment of co-morbid infections that are more prevalent among substance users. Although further mechanistic research is needed, findings from existing cohort studies have clear clinical implications. Implementing screening, brief intervention and referral to substance abuse treatment in HIV medical care could optimize health outcomes and decrease HIV transmission rates by boosting the effectiveness of "Test and Treat" approaches to HIV prevention.

Exhaustive exercise reduces TNF-α and IFN-α production in response to R-848 via toll-like receptor 7 in mice

Stressful exercise results in temporary immune depression. However, the impact of exercise on the immune responses via toll-like receptor (TLR) 7, which recognizes the common viral genomic feature, single-stranded RNA, remains unclear. To clarify the effect of stressful exercise on immune function in response to viral infection, we measured the changes in the plasma concentration of tumor necrosis factor (TNF)-α and interferon (IFN)-α, which are induced downstream from the TLR–ligand interaction, in exhaustive-exercised mice immediately after treatment with the imidazoquinoline R-848, which can bind to and activate TLR7. Both exhaustive-exercised (EX) and non-exercised (N-EX) male C3H/HeN mice were injected with R-848 (5 mg kg⁻¹), and blood samples were collected. In addition, RAW264 cells, which are mouse macrophage cells, were cultured 30 min after epinephrine (10 μM) or norepinephrine (10 μM) treatments, and were then stimulated with R-848 (10 μg ml⁻¹). In addition, the effect of propranolol (10 mg kg⁻¹) as blockade of β-adrenergic receptors on R-848-induced TNF-α and IFN-α production in the exercised mice was examined. Both the TNF-α and IFN-α concentrations in the plasma of EX were significantly lower than those in the plasma of N-EX after R-848 injection (P < 0.05 and P < 0.01, respectively), although the R-848 treatment increased the plasma TNF-α and IFN-α concentrations in both groups (P < 0.01, respectively). The R-848-induced TNF-α production in RAW264 cells was significantly inhibited by epinephrine and norepinephrine pre-treatment, although IFN-α was not detected. The propranolol treatment completely inhibited exercise-induced TNF-α and IFN-α suppression in response to R-848 in the mice. These data suggest that EX induces a reduction in TNF-α and IFN-α production in response to R-848, and that these phenomena might be regulated by an exercise-induced elevation of the systemic catecholamines.

Impact of acute psychosocial stress on peripheral blood gene expression pathways in healthy men

We investigated peripheral blood mononuclear cell gene expression responses to acute psychosocial stress to identify molecular pathways relevant to the stress response. Blood samples were obtained from 10 healthy male subjects before, during and after (at 0, 30, and 60 min) a standardized psychosocial laboratory stressor. Ribonucleic acid (RNA) was extracted and gene expression measured by hybridization to a 20,000-gene microarray. Gene Set Expression Comparisons (GSEC) using defined pathways were used for the analysis. Forty-nine pathways were significantly changed from baseline to immediately after the stressor (p < 0.05), implicating cell cycle, cell signaling, adhesion and immune responses. The comparison between stress and recovery (measured 30 min later) identified 36 pathways, several involving stress-responsive signaling cascades and cellular defense mechanisms. These results have relevance for understanding molecular mechanisms of the physiological stress response, and might be used to further study adverse health outcomes of psychosocial stress.

Adverse psychosocial factors predict poorer prognosis in HIV disease: a meta-analytic review of prospective investigations

There is a growing epidemiological literature focusing on the association between psychosocial stress and human immunodeficiency virus (HIV) disease progression or acquired immunodeficiency syndrome (AIDS), but inconsistent findings have been published. We aimed to quantify the association between adverse psychosocial factors and HIV disease progression. We searched Medline; PsycINFO; Web of Science; PubMed up to 19 January 2009, and included population studies with a prospective design that investigated associations between adverse psychosocial factors and HIV disease progression or AIDS. Two reviewers independently extracted data on study characteristics, quality, and estimates of associations. The overall meta-analysis examined 36 articles including 100 psychosocial and disease related relationships. It exhibited a small, but robust positive association between adverse psychosocial factors and HIV progression (correlation coefficient as combined size effect 0.059, 95% confidence interval 0.043-0.074, p<0.001). Notably, sensitivity analyses showed that personality types or coping styles and psychological distress were more strongly associated with greater HIV disease progression than stress stimuli per se, and that all of the immunological and clinical outcome indicators (acquired immunodeficiency syndrome stage, CD4+ T-cell decline, acquired immunodeficiency syndrome diagnosis, acquired immunodeficiency syndrome mortality, and human immunodeficiency virus disease or acquired immunodeficiency syndrome symptoms) except for viral load exhibited detrimental effects by adverse psychosocial factors. In conclusion, the current review reveals a robust relationship between adverse psychosocial factors and HIV disease progression. Furthermore, there would appear to be some evidence for particular psychosocial factors to be most strongly associated with HIV disease progression.

Health psychology: developing biologically plausible models linking the social world and physical health

Research over the past several decades has documented psychosocial influences on the development and progression of several major medical illnesses. The field is now increasingly focused on identifying the biological and behavioral mechanisms underlying these effects. This review takes stock of the knowledge accumulated in the biological arena to date and highlights conceptual and methodological approaches that have proven especially productive. It emphasizes the value of a disease-centered approach that "reverse engineers" adverse health outcomes into their specific biological determinants and then identifies psychologically modulated neuroendocrine and immunologic dynamics that modulate those pathological processes at the cellular and molecular levels.

Psychological distress, killer lymphocytes and disease severity in HIV/AIDS

Immunocellular mechanisms that account for the association between psychosocial risk factors and increased susceptibility to faster progression of HIV/AIDS are largely unknown. This study used structural equation modeling to test the hypothesis that enumerative and functional alterations in killer lymphocytes mediate the relationship between higher levels of psychological distress (defined by perceived stress, anxiety and depressive symptoms) and greater HIV disease severity (defined by HIV-1 viral load and T-helper (CD4(+)) cell count), independent of standard demographic and various HIV-related covariates. Participants were 200 HIV-1 seropositive adults on combination antiretroviral therapy (ages 20-55 years; 67% men; 62% black; 84% AIDS). The data fit a psychoimmune model in which the significant relationship between higher distress levels and greater disease severity was mediated by diminished natural killer (NK) cell count and cytotoxic function, as well as increased cytotoxic (CD8(+)) T-cell activation. Overall the findings indicated that the psychoimmune model accounted for 67% of the variation in HIV disease severity. In contrast, the data did not support a reverse directionality mediation model, where greater HIV disease severity predicted greater distress as a function of killer lymphocyte status. In sum, the psychoimmune associations of the final model are physiologically consistent and suggest that distress-related alterations in killer lymphocyte immunity may play a role in the biobehavioral mechanisms linked with HIV-1 pathogenesis.

Social temperament and lymph node innervation

Socially inhibited individuals show increased vulnerability to viral infections, and this has been linked to increased activity of the sympathetic nervous system (SNS). To determine whether structural alterations in SNS innervation of lymphoid tissue might contribute to these effects, we assayed the density of catecholaminergic nerve fibers in 13 lymph nodes from seven healthy adult rhesus macaques that showed stable individual differences in propensity to socially affiliate (Sociability). Tissues from Low Sociable animals showed a 2.8-fold greater density of catecholaminergic innervation relative to tissues from High Sociable animals, and this was associated with a 2.3-fold greater expression of nerve growth factor (NGF) mRNA, suggesting a molecular mechanism for observed differences. Low Sociable animals also showed alterations in lymph node expression of the immunoregulatory cytokine genes IFNG and IL4, and lower secondary IgG responses to tetanus vaccination. These findings are consistent with the hypothesis that structural differences in lymphoid tissue innervation might potentially contribute to relationships between social temperament and immunobiology.

Psychosocial influences on HIV-1 disease progression: neural, endocrine, and virologic mechanisms

This review surveys empirical research pertinent to the hypothesis that activity of the hypothalamus-pituitary-adrenal (HPA) axis and/or the sympathetic nervous system (SNS) might mediate biobehavioral influences on HIV-1 pathogenesis and disease progression. Data are considered based on causal effects of neuroeffector molecules on HIV-1 replication, prospective relationships between neural/endocrine parameters and HIV-relevant biological or clinical markers, and correlational data consistent with in vivo neural/endocrine mediation in human or animal studies. Results show that HPA and SNS effector molecules can enhance HIV-1 replication in cellular models via effects on viral infectivity, viral gene expression, and the innate immune response to infection. Animal models and human clinical studies both provide evidence consistent with SNS regulation of viral replication, but data on HPA mediation are less clear. Regulation of leukocyte biology by neuroeffector molecules provides a plausible biological mechanism by which psychosocial factors might influence HIV-1 pathogenesis, even in the era of effective antiretroviral therapy. As such, neural and endocrine parameters might provide useful biomarkers for gauging the promise of behavioral interventions and suggest novel adjunctive strategies for controlling HIV-1 disease progression.

SIV infection decreases sympathetic innervation of primate lymph nodes: the role of neurotrophins

The sympathetic nervous system regulates immune responses in part through direct innervation of lymphoid organs. Recent data indicate that viral infections can alter the structure of lymph node innervation. To determine the molecular mechanisms underlying sympathetic denervation during Simian Immunodeficiency Virus (SIV) infection, we assessed the expression of neurotrophic factors and neuromodulatory cytokines within lymph nodes from experimentally infected rhesus macaques. Transcription of nerve growth factor (NGF), brain-derived neurotropic factor (BDNF) and neurotrophin-4 (NT4) decreased significantly in vivo during chronic SIV infection, whereas expression of the neuro-inhibitory cytokine interferon-gamma (IFN gamma) was up-regulated. Acute SIV infection of macaque leukocytes in vitro induced similar changes in the expression of neurotrophic and neuro-inhibitory factors, indicative of an innate immune response. Statistical mediation analyses of data from in vivo lymph node gene expression suggested that coordinated changes in expression of multiple neuromodulatory factors may contribute to SIV-induced depletion of catecholaminergic varicosities within lymphoid tissue. Given previous evidence that lymph node catecholaminergic varicosities can enhance SIV replication in vivo, these results are consistent with the hypothesis that reduced expression of neurotrophic factors during infection could constitute a neurobiological component of the innate immune response to viral infection.

Stress-induced remodeling of lymphoid innervation

Lymphoid organs have long been known to harbor neural fibers from the sympathetic division of the autonomic nervous system, but recent studies suggest a surprising degree of plasticity in the density of innervation. This review summarizes data showing that behavioral stress can increase the density of catecholaminergic neural fibers within lymphoid organs of adult primates. Stress-induced neural densification is associated with increased expression of neurotrophic factors, and functional consequences include alterations in lymph node cytokine expression and increased replication of a lymphotropic virus. The finding that behavioral stress can tonically alter lymph node neural structure suggests that behavioral factors could exert long-term regulatory influences on the initiation, maintenance, and resolution of immune responses.

Social stress enhances sympathetic innervation of primate lymph nodes: mechanisms and implications for viral pathogenesis

Behavioral processes regulate immune system function in part via direct sympathetic innervation of lymphoid organs, but little is known about the factors that regulate the architecture of neural fibers in lymphoid tissues. In the present study, we find that experimentally imposed social stress can enhance the density of catecholaminergic neural fibers within axillary lymph nodes from adult rhesus macaques. This effect is linked to increased transcription of the key sympathetic neurotrophin nerve growth factor and occurs predominately in extrafollicular regions of the paracortex that contain T-lymphocytes and macrophages. Functional consequences of stress-induced increases in innervation density include reduced type I interferon response to viral infection and increased replication of the simian immunodeficiency virus. These data reveal a surprising degree of behaviorally induced plasticity in the structure of lymphoid innervation and define a novel pathway by which social factors can modulate immune response and viral pathogenesis.