Neural regulation of innate immunity: a coordinated nonspecific host response to pathogens

Does immune suppression during stress occur to promote physical performance?

Two adaptationist hypotheses have been proposed to explain why stress, particularly elevation of stress hormones (i.e., glucocorticoids), tends to suppress immune functions. One is that immune suppression represents efforts to minimize autoimmune responses to self-antigens released as organisms cope with stressors (i.e., the autoimmune-avoidance hypothesis). The other is that immune suppression occurs to promote a shunting of resources to life processes more conducive to survival of the stressor (i.e., the re-allocation hypothesis). Here in wild-caught house sparrows (Passer domesticus), we tested the second hypothesis, asking whether sustained elevation of baseline glucocorticoids, due to captivity, caused a greater rate of decline in immune functions than flight performance. A greater decline in immune functions than flight performance would support the re-allocation hypothesis. As in previous studies, we found that captivity tended to alter baseline corticosterone, suggesting that house sparrows experience captivity as a stressor. Captivity also affected several constitutive and induced innate immune metrics: bacterial (Escherichia coli) killing activity (BKA) of blood and oxidative burst of leukocytes both changed in a manner consistent with immune disregulation. In contrast, breast muscle size and vertical flight (hovering) duration improved over captivity. Collectively, these changes provide indirect support for the re-allocation hypothesis, although within individuals, changes in immune and physical performance were unrelated.

Mechanisms of action of topical corticosteroids in psoriasis

Psoriasis is a lifelong, chronic, and immune-mediated systemic disease, which affects approximately 1-3% of the Caucasian population. The different presentations of psoriasis require different approaches to treatment and appropriate prescriptions according to disease severity. The use of topical therapy remains a key component of the management of almost all psoriasis patients, and while mild disease is commonly treated only with topical agents, the use of topical therapy as adjuvant therapy in moderate-to-severe disease may also be helpful. This paper focuses on the cutaneous mechanisms of action of corticosteroids and on the currently available topical treatments, taking into account adverse effects, bioavailability, new combination treatments, and strategies to improve the safety of corticosteroids. It is established that the treatment choice should be tailored to match the individual patient's needs and his/her expectations, prescribing to each patient the most suitable vehicle.

Disturbances of the hypothalamic-pituitary-adrenal axis and plasma electrolytes during experimental sepsis

Background

Sepsis continues to be a poorly understood syndrome with a high mortality rate. While we are beginning to decipher the intricate interplay of the inflammatory response during sepsis, the precise regulation of the hypothalamic-pituitary-adrenal (HPA) axis and its impact on electrolyte homeostasis during sepsis remains incompletely understood.

Methods

Sepsis was induced in adult male Sprague-Dawley rats by cecal ligation and puncture (CLP). Plasma samples were obtained as a function of time (6-48 hrs) after CLP and compared with healthy animals (neg ctrl). Samples were analyzed for adrenocorticotropin (ACTH), corticosterone, and aldosterone levels, as well as concentrations of sodium (Na⁺), potassium (K⁺), chloride (Cl^-), and magnesium (Mg²⁺).

Results

ACTH levels were found to be significantly reduced 6-24 hrs after CLP in comparison to baseline levels and displayed gradual recovery during the later course (24-48 hrs) of sepsis. Plasma corticosterone concentrations exhibited a bell-shaped response, peaking between 6 and 12 hrs followed by rapid decline and concentrations below negative control levels 48 hrs after injury. Aldosterone levels in septic animals were continuously elevated between 6 and 48 hrs. Whereas plasma Na⁺ levels were found to be persistently elevated following CLP, levels of K⁺, Cl^- and Mg²⁺ were significantly reduced as a function of time and gradually recovered during the later course of sepsis.

Conclusions

CLP-induced sepsis resulted in dynamic changes of ACTH, corticosterone, and aldosterone levels. In addition, electrolyte levels showed significant disturbances after CLP. These electrolyte perturbations might be evoked by a downstream effect or a dysfunctional HPA-axis response during sepsis and contribute to severe complications during sepsis.

Brain-immune interactions and the neural basis of disease-avoidant ingestive behaviour

Neuro-immune interactions are widely manifested in animal physiology. Since immunity competes for energy with other physiological functions, it is subject to a circadian trade-off between other energy-demanding processes, such as neural activity, locomotion and thermoregulation. When immunity is challenged, this trade-off is tilted to an adaptive energy protecting and reallocation strategy that is identified as 'sickness behaviour'. We review diverse disease-avoidant behaviours in the context of ingestion, indicating that several adaptive advantages have been acquired by animals (including humans) during phylogenetic evolution and by ontogenetic experiences: (i) preventing waste of energy by reducing appetite and consequently foraging/hunting (illness anorexia), (ii) avoiding unnecessary danger by promoting safe environments (preventing disease encounter by olfactory cues and illness potentiation neophobia), (iii) help fighting against pathogenic threats (hyperthermia/somnolence), and (iv) by associative learning evading specific foods or environments signalling danger (conditioned taste avoidance/aversion) and/or at the same time preparing the body to counteract by anticipatory immune responses (conditioning immunomodulation). The neurobiology behind disease-avoidant ingestive behaviours is reviewed with special emphasis on the body energy balance (intake versus expenditure) and an evolutionary psychology perspective.

Stress and immune modulation in fish

Stress is an event that most animals experience and that induces a number of responses involving all three regulatory systems, neural, endocrine and immune. When the stressor is acute and short-term, the response pattern is stimulatory and the fish immune response shows an activating phase that specially enhances innate responses. If the stressor is chronic the immune response shows suppressive effects and therefore the chances of an infection may be enhanced. In addition, coping with the stressor imposes an allostatic cost that may interfere with the needs of the immune response. In this paper the mechanisms behind these immunoregulatory changes are reviewed and the role of the main neuroendocrine mechanisms directly affecting the building of the immune response and their consequences are considered.

Sedation & immunomodulation

As the armamentarium for sedation in the critically ill expands, opportunities will develop to modulate the immune responses of patients by way of the direct immune and neural-immune interactions of the sedatives. Control of autonomic activity through the use of appropriate sedation may be critical in this matter. Likewise analgesic-based sedation, with increased opioid dosage, may not prove beneficial in the setting of infection; whether avoidance of morphine in preference for a fentanyl derivative will help is unclear. However, as the immune effects seem dependent on the m receptor, it is improbable that a significant difference would be uncovered. Similarly, the present evidence suggests benzodiazepines are deleterious in infection; further studies are required urgently to evaluate this evidence. As an alternative to benzodiazepine-based sedation, dexmedetomidine has shown a remarkable 70% mortality benefit in a small secondary analysis of septic patients from the MENDS trial. Further powered clinical studies should now be undertaken to investigate the potential benefit of the α2-adrenoceptor agonist in this setting, with comparisons with propofol.

The modulation of catecholamines to the immune response against bacteria Vibrio anguillarum challenge in scallop Chlamys farreri

Catecholamines are pivotal signal molecules in the neuroendocrine-immune regulatory network, and implicated in the modulation of immune response. In the present study, the activities of some immune-related enzymes and the concentration of catecholamines were determined in circulating haemolymph of scallops Chlamys farreri after bacteria Vibrio anguillarum challenge. The activities of superoxide dismutase (SOD), catalase (CAT) and lysozyme (LYZ) increased significantly and reached 610 U mg(-1) at 12 h, 37.6 U mg(-1) at 6 h and 261.5 U mg(-1) at 6 h after bacteria challenge, respectively. The concentration of norepinephrine, epinephrine and dopamine also increased significantly and reached 114.9 ng mL(-1) at 12 h, 86.9 ng mL(-1) at 24 h and 480.4 pg mL(-1) at 12 h after bacteria challenge, respectively. Meanwhile, the activities of these immune-related enzymes in haemolymph were monitored in those scallops which were challenged by bacteria V. anguillarum and stimulated simultaneously with norepinephrine, epinephrine and adrenoceptor antagonist. The injection of norepinephrine and epinephrine repressed significantly the induction of bacteria challenge on the activities of immune-related enzymes, and they were reduced to about half of that in the control groups. The blocking of α and β-adrenoceptor by antagonist only repressed the increase of CAT and LYZ activities significantly, while no significant effect was observed on the increase of SOD activities. The collective results indicated that scallop catecholaminergic neuroendocrine system could be activated by bacteria challenge to release catecholamines after the immune response had been triggered, and the immune response against bacteria challenge could been negatively modulated by norepinephrine, epinephrine, and adrenoceptor antagonist. This information is helpful to further understand the immunomodulation of catecholamines in scallops.

Modulation of immune responses by the neuropeptide CGRP

The peripheral nervous system is connected with lymphoid organs through sensory nerves that mediate pain reflexes and may influence immune responses through the release of neuropeptides such as calcitonin gene-related peptide (CGRP). Local and systemic levels of CGRP increase rapidly during inflammatory responses. CGRP inhibits effector functions of various immune cells and dampens inflammation by distinct pathways involving the amplification of IL-10 production and/or the induction of the transcriptional repressor inducible cAMP early repressor (ICER). Thus, available evidence suggests that, in neuro-immunological interactions, CGRP mediates a potent peptidergic anti-inflammatory pathway.

[Molecular mechanisms regulating the activity of macrophages]

This article reviews modern concepts of the most common types of macrophage activation: classical, alternative, and type II. Molecular mechanisms of induction and regulation of these three types of activation are discussed. Any population of macrophages was shown to change its properties depending on its microenvironment and concrete biological situation (the "functional plasticity of macrophages"). Many intermediate states of macrophages were described along with the most pronounced and well-known activation types (classical activation, alternative activation, and type II activation). These intermediate states are characterized by a variety of combinations of their biological properties, including elements of the three afore mentioned types of activation. Macrophage activity is regulated by a complex network of interrelated cascade mechanisms.

Psychological stress in childhood and susceptibility to the chronic diseases of aging: moving toward a model of behavioral and biological mechanisms

Among people exposed to major psychological stressors in early life, there are elevated rates of morbidity and mortality from chronic diseases of aging. The most compelling data come from studies of children raised in poverty or maltreated by their parents, who show heightened vulnerability to vascular disease, autoimmune disorders, and premature mortality. These findings raise challenging theoretical questions. How does childhood stress get under the skin, at the molecular level, to affect risk for later diseases? And how does it incubate there, giving rise to diseases several decades later? Here we present a biological embedding model, which attempts to address these questions by synthesizing knowledge across several behavioral and biomedical literatures. This model maintains that childhood stress gets "programmed" into macrophages through epigenetic markings, posttranslational modifications, and tissue remodeling. As a consequence these cells are endowed with proinflammatory tendencies, manifest in exaggerated cytokine responses to challenge and decreased sensitivity to inhibitory hormonal signals. The model goes on to propose that over the life course, these proinflammatory tendencies are exacerbated by behavioral proclivities and hormonal dysregulation, themselves the products of exposure to early stress. Behaviorally, the model posits that childhood stress gives rise to excessive threat vigilance, mistrust of others, poor social relationships, impaired self-regulation, and unhealthy lifestyle choices. Hormonally, early stress confers altered patterns of endocrine and autonomic discharge. This milieu amplifies the proinflammatory environment already instantiated by macrophages. Acting in concert with other exposures and genetic liabilities, the resulting inflammation drives forward pathogenic mechanisms that ultimately foster chronic disease.

Psychiatric symptoms and proinflammatory cytokines in pregnancy

OBJECTIVE

Clinical studies suggest that psychiatric symptoms, particularly depression, anxiety, and trauma, may be associated with inflammation, as indexed by proinflammatory cytokines. Such a link may be especially significant in pregnancy and may shed additional light on the etiology of perinatal mood disorders.

METHODS

We prospectively observed 145 women selected from a community obstetric clinic serving a primarily low-income, high-psychosocial risk population. Women without evidence of medical high-risk pregnancies were screened (including psychiatric and trauma histories) and then assessed in detail (e.g., mood symptoms) at approximately 18 and 32 weeks' gestation. Blood was drawn to measure key proinflammatory markers, interleukin 6 and tumor necrosis factor α (TNF-α). Data on pregnancy and obstetric outcome were derived from medical records.

RESULTS

There was considerable stability of cytokine levels within individuals and a significant mean increase across pregnancy observed for interleukin 6 (p < .001) and TNF-α (p < .001). History of trauma was associated with significantly elevated TNF-α levels (F(1,135) = 4.43, p < .05), controlling for psychosocial and obstetric covariates. In contrast, elevated measures of depression and anxiety were unrelated to proinflammatory cytokines (p > .1). Exploratory analyses indicated that neither psychiatric symptoms nor proinflammatory cytokines predicted birth weight, gestational age, or obstetric complications.

CONCLUSIONS

These findings suggest that antecedent trauma may be associated with persistently elevated TNF-α levels during pregnancy. The evidence that a generalized proinflammatory state was associated with symptoms of depression or anxiety in pregnant women was not found.

Acute amygdaloid response to systemic inflammation

The amygdala, a group of nuclei located in the medial temporal lobe, is a key limbic structure involved in mood regulation, associative learning, and modulation of cognitive functions. Functional neuroanatomical studies suggest that this brain region plays also an important role in the central integration of afferent signals from the peripheral immune system. In the present study, intracerebral electroencephalography and microdialysis were employed to investigate the electrophysiological and neurochemical consequences of systemic immune activation in the amygdala of freely moving rats. Intraperitoneal administration of bacterial lipopolysaccharide (100 μg/kg) induced with a latency of about 2 h a significant increase in amygdaloid neuronal activity and a substantial rise in extracellular noradrenaline levels. Activated neurons in the amygdaloid complex, identified by c-Fos immunohistochemistry, were mainly located in the central nucleus and, to a lesser extent, in the basolateral nucleus of the amygdala. Gene expression analysis in micropunches of the amygdala revealed that endotoxin administration induced a strong time-dependent increase in IL-1β, IL-6, and TNF-α mRNA levels indicating that these cytokines are de novo synthesized in the amygdala in response to peripheral immune activation. The changes in amygdaloid activity were timely related to an increase in anxiety-like behavior and decreased locomotor activity and exploration in the open-field. Taken together, these data give novel insights into different features of the acute amygdaloid response during experimental inflammation and provides further evidence that the amygdala integrates immune-derived information to coordinate behavioral and autonomic responses.

Organ-specific features of natural killer cells

Natural killer (NK) cells can be swiftly mobilized by danger signals and are among the earliest arrivals in target organs of disease. However, the role of NK cells in regulating inflammatory responses is far from completely understood in different organs. It is often complex and sometimes paradoxical.

The phenotypes and functions of NK cells in the liver, mucosal tissues, uterus, pancreas, joints and brain are influenced by the unique cellular interactions and the local microenvironment within each organ.

Hepatic NK cells exhibit an activated phenotype with high levels of cytotoxic effector molecules. These cells have been implicated in promoting liver injury and inhibiting liver fibrosis and regeneration. The liver is also enriched in NK cells with memory-like adaptive immune features.

NK cells are detected in healthy lymphoid tissues of the lung, skin and gut, and are recruited to these tissues during infection or inflammation. In the gastrointestinal tract, classical NK cells and a variety of innate lymphoid cells, such as the family of lymphoid tissue-inducer (LTi) cells, are likely to have crucial roles in controlling inflammatory responses.

NK cells represent the major lymphocyte subset in the pregnant uterus, with a unique phenotype resembling an early developmental state. Emerging evidence indicates that these cells play a crucial part in mediating the uterine vascular adaptations to pregnancy and promoting the maintenance of healthy pregnancy.

In non-obese diabetic (NOD) mice, NK cells are recruited early to the pancreas, become locally activated and then adopt a hyporesponsive phenotype. Although NK cells have a pathogenic role in the natural progression of diabetes in NOD mice, they contribute to diabetes protection induced by complete Freund's adjuvant and to islet allograft tolerance induced by co-stimulatory blockade.

NK cells in the inflamed joint uniquely express receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF), which promote osteoclast differentiation. Although NK cells have a pathogenic role in collagen-induced arthritis in mice, they are also crucial for protection against antibody-induced arthritis mediated by CpG oligonucleotides.

Studies in a mouse model of multiple sclerosis have shown that NK cells arrive in the central nervous system (CNS) before pathogenic T cells and have a protective role in the development of CNS inflammation, probably by killing CNS-resident microglia that prime effector T cells.

During evolution, different organs might have evolved distinct ways to recruit and influence the effector functions of NK cells. Once we understand these mechanisms, the next challenge will be to exploit this information for harnessing NK cells to develop prophylactic and therapeutic measures against infectious agents, tumours and inflammatory diseases.

Each tissue in our body contains a unique microenvironment that can differentially shape immune reactivity. In this Review article, Shiet al. describe how organ-specific factors influence natural killer cell homing and phenotype, and discuss the local molecular and cellular interactions that determine the protective or pathogenic functions of natural killer cells in the different tissues.

Natural killer (NK) cells can be swiftly mobilized by danger signals and are among the earliest arrivals at target organs of disease. However, the role of NK cells in mounting inflammatory responses is often complex and sometimes paradoxical. Here, we examine the divergent phenotypic and functional features of NK cells, as deduced largely from experimental mouse models of pathophysiological responses in the liver, mucosal tissues, uterus, pancreas, joints and brain. Moreover, we discuss how organ-specific factors, the local microenvironment and unique cellular interactions may influence the organ-specific properties of NK cells.

Hydrogen sulfide and neurogenic inflammation in polymicrobial sepsis: involvement of substance P and ERK-NF-κB signaling

Hydrogen sulfide (H(2)S) has been shown to induce transient receptor potential vanilloid 1 (TRPV1)-mediated neurogenic inflammation in polymicrobial sepsis. However, endogenous neural factors that modulate this event and the molecular mechanism by which this occurs remain unclear. Therefore, this study tested the hypothesis that whether substance P (SP) is one important neural element that implicates in H(2)S-induced neurogenic inflammation in sepsis in a TRPV1-dependent manner, and if so, whether H(2)S regulates this response through activation of the extracellular signal-regulated kinase-nuclear factor-κB (ERK-NF-κB) pathway. Male Swiss mice were subjected to cecal ligation and puncture (CLP)-induced sepsis and treated with TRPV1 antagonist capsazepine 30 minutes before CLP. DL-propargylglycine (PAG), an inhibitor of H(2)S formation, was administrated 1 hour before or 1 hour after sepsis, whereas sodium hydrosulfide (NaHS), an H(2)S donor, was given at the same time as CLP. Capsazepine significantly attenuated H(2)S-induced SP production, inflammatory cytokines, chemokines, and adhesion molecules levels, and protected against lung and liver dysfunction in sepsis. In the absence of H(2)S, capsazepine caused no significant changes to the PAG-mediated attenuation of lung and plasma SP levels, sepsis-associated systemic inflammatory response and multiple organ dysfunction. In addition, capsazepine greatly inhibited phosphorylation of ERK(1/2) and inhibitory κBα, concurrent with suppression of NF-κB activation even in the presence of NaHS. Furthermore, capsazepine had no effect on PAG-mediated abrogation of these levels in sepsis. Taken together, the present findings show that H(2)S regulates TRPV1-mediated neurogenic inflammation in polymicrobial sepsis through enhancement of SP production and activation of the ERK-NF-κB pathway.

Differential immune system DNA methylation and cytokine regulation in post-traumatic stress disorder

DNA methylation may mediate persistent changes in gene function following chronic stress. To examine this hypothesis, we evaluated African American subjects matched by age and sex, and stratified into four groups by post-traumatic stress disorder (PTSD) diagnosis and history of child abuse. Total Life Stress (TLS) was also assessed in all subjects. We evaluated DNA extracted from peripheral blood using the HumanMethylation27 BeadChip and analyzed both global and site-specific methylation. Methylation levels were examined for association with PTSD, child abuse history, and TLS using a linear mixed model adjusted for age, sex, and chip effects. Global methylation was increased in subjects with PTSD. CpG sites in five genes (TPR, CLEC9A, APC5, ANXA2, and TLR8) were differentially methylated in subjects with PTSD. Additionally, a CpG site in NPFFR2 was associated with TLS after adjustment for multiple testing. Notably, many of these genes have been previously associated with inflammation. Given these results and reports of immune dysregulation associated with trauma history, we compared plasma cytokine levels in these subjects and found IL4, IL2, and TNFα levels associated with PTSD, child abuse, and TLS. Together, these results suggest that psychosocial stress may alter global and gene-specific DNA methylation patterns potentially associated with peripheral immune dysregulation. Our results suggest the need for further research on the role of DNA methylation in stress-related illnesses.

Effects of bilateral adrenalectomy on the innate immune responses following trauma in rats

BACKGROUND

The regulation of neuroendocrine hormones on the innate immune responses in trauma has not been fully understood. Previous studies have shown that the neuroendocrine hormones are important factors in their effects on immune parameters, depending on their concentration and timing instead of the simple suppressive effects.

MATERIALS AND METHODS

A total of 144 Sprague–Dawley rats were divided randomly into sham, pulmonary blast injury (BI) and adrenalectomy plus pulmonary BI groups. Bilateral adrenalectomy was performed on rats, which were then subjected to blast injury. Following this, peripheral leucocyte responsiveness to lipopolysaccharide (LPS) stimulation, phagocytosis activities of macrophages and bacteria translocation (BT) were examined. Tumour necrosis factor-a (TNF-a) levels and the expression levels of scavenger receptor (SR) A, CD14, Toll-like receptor (TLR) 4 and MD2 were assayed with enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction, respectively.

RESULTS

In adrenalectomised rats after pulmonary BI, the number of peripheral leucocytes was increased and the phagocytosis of peritoneal and splenic macrophages was decreased as compared to the BI group. Simultaneously, the gut-derived BT and TNF-a secretion in lung tissues were elevated, whilst the LPS-stimulated TNF-a synthesis by peripheral leucocyte responsiveness was reduced. Furthermore, the mRNA levels of SR-A, CD14, TLR4 and MD2 in lung tissues of adrenalectomised rats decreased. Adrenalectomised rats showed enhancement of inflammatory responses and severe tissue injuries in trauma.

CONCLUSIONS

Release of adrenal hormones might enhance, rather than inhibit, the innate immune functions, particularly in the early stages of trauma.

Neuronal circuitry regulates the response of Caenorhabditis elegans to misfolded proteins

The consequence of chronic protein misfolding is the basis of many human diseases. To combat the deleterious effects of accumulated protein damage, all cells possess robust quality-control systems, specifically molecular chaperones and clearance machineries, that sense and respond to protein misfolding. However, for many protein conformational diseases, it is unclear why this quality-control system does not efficiently counter protein aggregation. Previous findings that the heat shock response in Caenorhabditis elegans is regulated by thermosensory neurons led us to consider whether neuronal activity could also be responsible for the inadequate response of an organism to chronic protein misfolding. Here we show, in animals expressing polyglutamine expansion proteins and mutant SOD-1(G93A) in intestinal or muscle cells, that the nervous system does indeed control the cellular response to misfolded proteins. Whereas polyglutamine expansion-expressing animals with WT thermosensory neurons readily express protein aggregates, leading to cellular dysfunction without concomitant up-regulation of molecular chaperones, modulation of the nervous system results in chaperone up-regulation that suppresses aggregation and toxicity. The neuronal signal is transmitted through calcium-activated dense core vesicle neurosecretion. Cell-nonautonomous control of chaperone expression by the thermosensory neurons allows C. elegans to respond differently to acute stress such as heat shock, and chronic stress caused by the expression of misfolded proteins, suggesting that neuronal signaling determines the course of cellular proteotoxicity.

β2-Adrenoreceptors of regulatory lymphocytes are essential for vagal neuromodulation of the innate immune system

The nervous system is classically organized into sympathetic and parasympathetic systems acting in opposition to maintain physiological homeostasis. Here, we report that both systems converge in the activation of β2-adrenoceptors of splenic regulatory lymphocytes to control systemic inflammation. Vagus nerve stimulation fails to control serum TNF levels in either β2-knockout or lymphocyte-deficient nude mice. Unlike typical suppressor CD25(+) cells, the transfer of CD4(+)CD25(-) regulatory lymphocytes reestablishes the anti-inflammatory potential of the vagus nerve and β2-agonists to control inflammation in both β2-knockout and nude mice. β2-Agonists inhibit cytokine production in splenocytes (IC(50)≈ 1 μM) and prevent systemic inflammation in wild-type but not in β2-knockout mice. β2-Agonists rescue wild-type mice from established polymicrobial peritonitis in a clinically relevant time frame. Regulatory lymphocytes reestablish the anti-inflammatory potential of β2-agonists to control systemic inflammation, organ damage, and lethal endotoxic shock in β2-knockout mice. These results indicate that β2-adrenoceptors in regulatory lymphocytes are critical for the anti-inflammatory potential of the parasympathetic vagus nerve, and they represent a potential pharmacological target for sepsis.

Corticotropin releasing factor-1 receptor antagonism alters the biochemical, but not behavioral effects of repeated interleukin-1β administration

Activation of the immune system via administration of cytokines is used for the treatment of chronic viral infections such as hepatitis C and for cancers resistant to radiotherapy. Cytokine-based treatments induce a range of "sickness" behaviors (e.g. depression, anxiety, pain, anorexia, and fatigue). Activation of the hypothalamic pituitary-adrenal axis via the induction of corticotropin releasing factor (CRF) may underlie these unwanted side effects. This study used repeated systemic injections of the pro-inflammatory cytokine interleukin-1β (IL-1β) to model the sickness behaviors and biochemical effects of immune system activation. We assessed the ability of CRF type I receptor (CRF(1)) antagonism to reduce biochemical and behavioral signs of sickness induced by IL-1β treatment. Forty Wistar rats were assigned to one of four groups: 1) saline+vehicle; 2) saline+DMP904 (CRF(1) antagonist); 3) IL-1β+vehicle; 4) IL-1β+DMP904. Rats received intraperitoneal injections of either DMP904 or vehicle and of IL-1β or saline for six days. Sickness behavior was evaluated using body weight assessments and forced swim testing (FST). Blood and brain samples were collected to measure cytokine, p38 mitogen-activated protein kinase (MAPK), and phospho-p38 MAPK levels using multiplex techniques. There were significant reductions in body weights and FST immobility times associated with IL-1β administration. Rats administered IL-1β had significantly higher serum levels of IL-10, but not interferon-γ. Within the hippocampus, IL-1β reduced levels of p38 MAPK, but had no impact on levels of phospho-p38 MAPK except in the presence of DMP904. When administered alone, DMP904 had no significant effect on p38 MAPK or phospho-p38 MAPK in the hippocampus, but when given with IL-1β led to increased phosphorylation of p38 MAPK. IL-1β and DMP904 reduced levels of p38 MAPK within the hypothalamus, while co-administration of IL-1β and DMP904 abolished the effects of either drug alone. IL-1β decreased immobility time in the FST, and led to reductions in body weight, changes in serum cytokine levels and p38 MAPK regulation within the hippocampus and hypothalamus. DMP904 blocked some of the neurochemical effects of IL-1β, but did not impact the behavioral measures, or serum cytokines. Thus, additional studies will be needed to determine whether CRF(1) antagonism is an effective treatment for cytokine-induced sickness. This article is part of a Special Issue entitled 'Anxiety and Depression'.

Captivity induces hyper-inflammation in the house sparrow (Passer domesticus)

Some species thrive in captivity but others exhibit extensive psychological and physiological deficits, which can be a challenge to animal husbandry and conservation as well as wild immunology. Here, we investigated whether captivity duration impacted the regulation of a key innate immune response, inflammation, of a common wild bird species, the house sparrow (Passer domesticus). Inflammation is one of the most commonly induced and fast-acting immune responses animals mount upon exposure to a parasite. However, attenuation and resolution of inflammatory responses are partly coordinated by glucocorticoid hormones, hormones that can be disregulated in captivity. Here, we tested whether captivity duration alters corticosterone regulation and hence the inflammatory response by comparing the following responses to lipopolysaccharide (LPS; a Gram-negative bacteria component that induces inflammation) of birds caught wild and injected immediately versus those held for 2 or 4 weeks in standard conditions: (1) the magnitude of leukocyte immune gene expression [the cytokines, interleukin 1β and interleukin 6, and Toll-like receptor 4 (TLR4)], (2) the rate of clearance of endotoxin, and (3) the release of corticosterone (CORT) in response to endotoxin (LPS). We predicted that captivity duration would increase baseline CORT and thus suppress gene expression and endotoxin clearance rate. However, our predictions were not supported: TLR4 expression increased with time in captivity irrespective of LPS, and cytokine expression to LPS was stronger the longer birds remained captive. Baseline CORT was not affected by captivity duration, but CORT release post-LPS occurred only in wild birds. Lastly, sparrows held captive for 4 weeks maintained significantly higher levels of circulating endotoxin than other groups, perhaps due to leakage of microbes from the gut, but exogenous LPS did not increase circulating levels over the time scale samples were collected. Altogether, captivity appears to have induced a hyper-inflammatory state in house sparrows, perhaps due to disregulation of glucocorticoids, natural microflora or both.

Cholinergic regulatory lymphocytes re-establish neuromodulation of innate immune responses in sepsis

Many anti-inflammatory strategies that are successful in treating sepsis in healthy animals fail in clinical trials, in part because sepsis normally involves immunocompromised patients, and massive lymphocyte apoptosis prevents immunomodulation. In this article, we report a new set of regulatory lymphocytes that are able to re-establish the cholinergic anti-inflammatory modulation and to provide therapeutic advantages in sepsis. The vagus nerve controls inflammation in healthy, but not in septic, mice. Likewise, vagus nerve and cholinergic agonists fail to control inflammation in splenectomized and nude animals. Unlike typical suppressor CD25(+) cells, CD4(+)CD25(-) lymphocytes re-establish the anti-inflammatory potential of the vagus nerve and cholinergic agonists in immunocompromised and septic animals. These cholinergic lymphocytes re-establish splenic protection and the potential of cholinergic agonists to rescue immunocompromised animals from established sepsis. The study results revealed these new regulatory lymphocytes as, to our knowledge, the first known physiological target for neuromodulation of the innate immune responses and a potential therapeutic target for sepsis.

Inflammation and the nervous system: the connection in the cornea in patients with infectious keratitis

PURPOSE

To study the density and morphologic characteristics of epithelial dendritic cells, as correlated to subbasal corneal nerve alterations in acute infectious keratitis (IK) by in vivo confocal microscopy (IVCM).

METHODS

IVCM of the central cornea was performed prospectively in 53 eyes with acute bacterial (n = 23), fungal (n = 13), and Acanthamoeba (n = 17) keratitis, and in 20 normal eyes, by using laser in vivo confocal microscopy. Density and morphology of dendritic-shaped cells (DCs) of the central cornea, corneal nerve density, nerve numbers, branching, and tortuosity were assessed and correlated. It should be noted that due to the "in vivo" nature of the study, the exact identity of these DCs cannot be specified, as they could be monocytes or tissue macrophages, but most likely dendritic cells.

RESULTS

IVCM revealed the presence of central corneal DCs in all patients and controls. The mean DC density was significantly higher in patients with bacterial (441.1 ± 320.5 cells/mm(2); P < 0.0001), fungal (608.9 ± 812.5 cells/mm(2); P < 0.0001), and Acanthamoeba keratitis (1000.2 ± 1090.3 cells/mm(2); P < 0.0001) compared with controls (49.3 ± 39.6 cells/mm(2)). DCs had an increased size and dendrites in patients with IK. Corneal nerves were significantly reduced in eyes with IK compared with controls across all subgroups, including nerve density (674.2 ± 976.1 vs. 3913.9 ± 507.4 μm/frame), total nerve numbers (2.7 ± 3.9 vs. 20.2 ± 3.3), main trunks (1.5 ± 2.2 vs. 6.9 ± 1.1), and branching (1.2 ± 2.0 vs. 13.5 ± 3.1; P < 0.0001). A strong association between the diminishment of corneal nerves and the increase of DC density was observed (r = -0.44; P < 0.0005).

CONCLUSIONS

IVCM reveals an increased density and morphologic changes of central epithelial DCs in infectious keratitis. There is a strong and significant correlation between the increase in DC numbers and the decreased subbasal corneal nerves, suggesting a potential interaction between the immune and nervous system in the cornea.

Dexamethasone prophylaxis in pediatric open heart surgery is associated with increased blood long pentraxin PTX3: potential clinical implications

Glucocorticoid administration before cardiopulmonary bypass (CPB) can reduce the systemic inflammatory response and improve clinical outcome. Long pentraxin PTX3 is a novel inflammatory parameter that could play a protective cardiovascular role by regulating inflammation. Twenty-nine children undergoing open heart surgery were enrolled in the study. Fourteen received dexamethasone (1st dose 1.5 mg/Kg i.v. or i.m. the evening before surgery; 2nd dose 1.5 mg/kg i.v. before starting bypass) and fifteen children served as control. Blood PTX3, short pentraxin C-reactive protein (CRP), interleukin-1 receptor II (IL-1RII), fibrinogen and partial thromboplastin time (PTT) were assayed at different times. PTX3 levels significantly increased during CPB in dexamethasone-treated (+D) and dexamethasone-untreated (−D) subjects, but were significantly higher in +D than −D patients. CRP levels significantly increased both in +D and −D patients in the postoperative days, with values significantly higher in −D than +D patients. Fibrinogen and PTT values were significantly higher in −D than +D patients in the 1st postoperative day. IL-1RII plasma levels increased in the postoperative period in both groups. Dexamethasone prophylaxis in pediatric patients undergoing CPB for cardiac surgery is associated with a significant increase of blood PTX3 that could contribute to decreasing inflammatory parameters and improving patient clinical outcome.

Tissue expression of steroid hormone receptors is associated with differential immune responsiveness

Glucocorticoids have been used as treatments against a number of diseases, especially autoimmune/inflammatory conditions in which the immune system is overactive. These treatments have varying degrees of responsiveness among individuals and in different tissues (including brain); therefore, it is important to determine what could account for these differences. In this study, we evaluated expression of stress hormone receptors in immune cells from lymphoid and non-lymphoid tissues (including brain) as a possible explanation. We analyzed leukocytes (CD45(+)) in kidney, liver, spleen, and thymus tissues from healthy mice for expression of the receptor for stress hormone (glucocorticoid-GR) as well as other steroid hormones (androgen-AR, progesterone-PR) and found that all tissues expressed these steroid hormone receptors but with varying patterns. To determine whether tissue-specific differences were related to immune cell composition, we examined steroid hormone receptor expression in T lymphocytes from each of these tissues and found similar patterns of expression in these cells regardless of tissue source. Because glucocorticoids can also impact brain function, we further examined expression of the stress hormone receptor in brain tissue and found GR expressed in immune cells at this site. In order to investigate the potential impact in an area of neuropathology, we utilized a mouse model of West Nile Virus (WNV). We observed pathological changes in brains of WNV-infected animals and T lymphocytes in the areas of inflammation; however, these cells did not express GR. These data indicate that tissue-specific differences in steroid hormone receptor expression by immune cells could determine responsiveness to steroid hormone treatment.

Modeling autonomic regulation of cardiac function and heart rate variability in human endotoxemia

Heart rate variability (HRV), the quantification of beat-to-beat variability, has been studied as a potential prognostic marker in inflammatory diseases such as sepsis. HRV normally reflects significant levels of variability in homeostasis, which can be lost under stress. Much effort has been placed in interpreting HRV from the perspective of quantitatively understanding how stressors alter HRV dynamics, but the molecular and cellular mechanisms that give rise to both homeostatic HRV and changes in HRV have received less focus. Here, we develop a mathematical model of human endotoxemia that incorporates the oscillatory signals giving rise to HRV and their signal transduction to the heart. Connections between processes at the cellular, molecular, and neural levels are quantitatively linked to HRV. Rhythmic signals representing autonomic oscillations and circadian rhythms converge to modulate the pattern of heartbeats, and the effects of these oscillators are diminished in the acute endotoxemia response. Based on the semimechanistic model developed herein, homeostatic and acute stress responses of HRV are studied in terms of these oscillatory signals. Understanding the loss of HRV in endotoxemia serves as a step toward understanding changes in HRV observed clinically through translational applications of systems biology based on the relationship between biological processes and clinical outcomes.

Inflammation and cardiorespiratory control: the role of the vagus nerve

Inflammation and immunity have been implicated in a wide variety of diseases and disorders ranging from asthma to cardiovascular disease to hemorrhagic shock. In this review we will briefly consider the evidence for the neural concomitants of immunomodulation. First, we will briefly review the anatomy and physiology of the cardiorespiratory system. Then we will review the anatomy and physiology of neural-immune communication. The nucleus of the solitary tract is a site of integration of both the afferent and efferent neural regulation of the cardiorespiratory as well as the immune system. Then we will provide an overview of what is known about neuroimmunomodulation from both animal and human studies including neuroimaging and clinical studies. Finally, we will discuss a possible role of this neural circuitry in asthma related health disparities.

Innate immunity and monocyte-macrophage activation in atherosclerosis

Innate inflammation is a hallmark of both experimental and human atherosclerosis. The predominant innate immune cell in the atherosclerotic plaque is the monocyte-macrophage. The behaviour of this cell type within the plaque is heterogeneous and depends on the recruitment of diverse monocyte subsets. Furthermore, the plaque microenvironment offers polarisation and activation signals which impact on phenotype. Microenvironmental signals are sensed through pattern recognition receptors, including toll-like and NOD-like receptors - the latter of which are components of the inflammasome - thus dictating macrophage behaviour and outcome in atherosclerosis. Recently cholesterol crystals and modified lipoproteins have been recognised as able to directly engage these pattern recognition receptors. The convergent role of such pathways in terms of macrophage activation is discussed in this review.

A dopa decarboxylase modulating the immune response of scallop Chlamys farreri

Background

Dopa decarboxylase (DDC) is a pyridoxal 5-phosphate (PLP)-dependent enzyme that catalyzes the decarboxylation of L-Dopa to dopamine, and involved in complex neuroendocrine-immune regulatory network. The function for DDC in the immunomodulation remains unclear in invertebrate.

Methodology

The full-length cDNA encoding DDC (designated CfDDC) was cloned from mollusc scallop Chlamys farreri. It contained an open reading frame encoding a polypeptide of 560 amino acids. The CfDDC mRNA transcripts could be detected in all the tested tissues, including the immune tissues haemocytes and hepatopancreas. After scallops were treated with LPS stimulation, the mRNA expression level of CfDDC in haemocytes increased significantly (5.5-fold, P<0.05) at 3 h and reached the peak at 12 h (9.8-fold, P<0.05), and then recovered to the baseline level. The recombinant protein of CfDDC (rCfDDC) was expressed in Escherichia coli BL21 (DE3)-Transetta, and 1 mg rCfDDC could catalyze the production of 1.651±0.22 ng dopamine within 1 h in vitro. When the haemocytes were incubated with rCfDDC-coated agarose beads, the haemocyte encapsulation to the beads was increased significantly from 70% at 6 h to 93% at 24 h in vitro in comparison with that in the control (23% at 6 h to 25% at 24 h), and the increased haemocyte encapsulation was repressed by the addition of rCfDDC antibody (which is acquired via immunization 6-week old rats with rCfDDC). After the injection of DDC inhibitor methyldopa, the ROS level in haemocytes of scallops was decreased significantly to 0.41-fold (P<0.05) of blank group at 12 h and 0.47-fold (P<0.05) at 24 h, respectively.

Conclusions

These results collectively suggested that CfDDC, as a homologue of DDC in scallop, modulated the immune responses such as haemocytes encapsulation as well as the ROS level through its catalytic activity, functioning as an indispensable immunomodulating enzyme in the neuroendocrine-immune regulatory network of mollusc.

α7-cholinergic receptor mediates vagal induction of splenic norepinephrine

Classically, sympathetic and parasympathetic systems act in opposition to maintain the physiological homeostasis. In this article, we report that both systems work together to restrain systemic inflammation in life-threatening conditions such as sepsis. This study indicates that vagus nerve and cholinergic agonists activate the sympathetic noradrenergic splenic nerve to control systemic inflammation. Unlike adrenalectomy, splenectomy and splenic neurectomy prevent the anti-inflammatory potential of both the vagus nerve and cholinergic agonists, and abrogate their potential to induce splenic and plasma norepinephrine. Splenic nerve stimulation mimics vagal and cholinergic induction of norepinephrine and re-establishes neuromodulation in α7 nicotinic acetylcholine receptor (α7nAChR)-deficient animals. Thus, vagus nerve and cholinergic agonists inhibit systemic inflammation by activating the noradrenergic splenic nerve via the α7nAChR nicotinic receptors. α7nAChR represents a unique molecular link between the parasympathetic and sympathetic system to control inflammation.

GPA-9 is a novel regulator of innate immunity against Escherichia coli foods in adult Caenorhabditis elegans

Innate immune responses to pathogens are governed by the nervous system. Here, we investigated the molecular mechanism underlying innate immunity in Caenorhabditis elegans against Escherichia coli OP50, a standard laboratory C. elegans food. Longevity was compared in worms fed live or UV-killed OP50 at low or high density food condition (HDF). Expression of the antimicrobial gene lys-8 was approximately 5-fold higher in worms fed live OP50, suggesting activation of innate immunity upon recognition of OP50 metabolites. Lifespan was extended and SOD-3 mRNA levels were increased in gpa-9-overexpressing gpa-9XS worms under HDF in association with robust induction of insulin/IGF-1 signaling (IIS). Expression of ins-7 and daf-28 that control lys-8 expression was reduced in gpa-9XS, indicating that GPA-9-mediated immunity is due in part to ins-7 and daf-28 downregulation. Our results suggest that OP50 metabolites in amphid neurons elicit innate immunity through the IIS pathway, and identify GPA-9 as a novel regulator of both the immune system and aging in C. elegans.

The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights

Since the discovery of glucocorticoids in the 1940s and the recognition of their anti-inflammatory effects, they have been amongst the most widely used and effective treatments to control inflammatory and autoimmune diseases. However, their clinical efficacy is compromised by the metabolic effects of long-term treatment, which include osteoporosis, hypertension, dyslipidaemia and insulin resistance/type 2 diabetes mellitus. In recent years, a great deal of effort has been invested in identifying compounds that separate the beneficial anti-inflammatory effects from the adverse metabolic effects of glucocorticoids, with limited effect. It is clear that for these efforts to be effective, a greater understanding is required of the mechanisms by which glucocorticoids exert their anti-inflammatory and immunosuppressive actions. Recent research is shedding new light on some of these mechanisms and has produced some surprising new findings. Some of these recent developments are reviewed here.

Neuroimmune pharmacology as a sub-discipline of medical neuroscience in the medical school curriculum

The emerging field of neuroimmune pharmacology (NIP) is the confluence of three distinct disciplines: neuroscience, immunology, and pharmacology (Gendelman and Ikezu 2008). NIP was born from the realization that inflammation within the central nervous system (CNS) plays a crucial role in many neurological pathologies and as such offers a rich array of novel pharmacological targets as potential therapeutics. As this field is likely to have a major impact in medical science, educating future physicians on this area will help increase awareness and may potentially inspire them to pursue careers in the field of NIP. However, a key challenge for medical educators, is how best to incorporate new material on emerging fields, such as NIP, into the medical school curriculum, specifically in the context of a medical neuroscience course. We propose the addition of two 50-min lectures plus an additional optional 2-h lab module to the standard first year medical neuroscience class curriculum. Lecture 1 will focus on how the CNS and the immune system inter-communicate with one another with emphasis on neuroanatomical features and chemical signal transduction between the two systems. Lecture 2 provides an introduction to inflammation in the CNS and provides a series of clinical correlates to describe how CNS inflammation contributes to the disease process. The lab module provides detailed visual examples of how CNS inflammation influences disease processes and provides two examples of how application of an immunomodulatory pharmacological agent can modify disease processes.

Variability in stress system regulatory control of inflammation: a critical factor mediating health effects of stress

Chronic stress has been associated with disease but the biological pathways are not completely understood. Stress systems such as the hypothalamus-pituitary-adrenal axis and the autonomic nervous system are prime candidates but alterations in their baseline activity are not consistently found in chronic stress. Evidence suggests that stress-related changes in the sensitivity of inflammatory pathways towards glucocorticoid regulation, that is, the development of glucocorticoid resistance, might help explain inflammatory disinhibition and the subsequent development of disease. Recent data show a similarly important role for sympathetic and parasympathetic modulation of the inflammatory cascade for the maintenance of health. This article argues that variation of target tissue sensitivity towards anti-inflammatory effects of the hypothalamus-pituitary-adrenal axis, as well as sympathetic and parasympathetic signaling, might be involved in the development of low-grade inflammation under chronic psychosocial stress.

Epidemiology of stress and asthma: from constricting communities and fragile families to epigenetics

Several epidemiologic frameworks, exemplified through extant research examples, provide insight into the role of stress in the expression of asthma and other allergic disorders. Biologic, psychological, and social processes interact throughout the life course to influence disease expression. Studies exploiting a child development framework focus on critical periods of exposure, including the in utero environment, to examine the influence of stress on disease onset. Early stress effects that alter the normal course of morphogenesis and maturation that affect both structure and function of key organ systems (eg, immune, respiratory) may persist into adult life underscoring the importance of a life course perspective. Other evidence suggests that maternal stress influences programming of integrated physiologic systems in their offspring (eg, neuroendocrine, autonomic, immune function) starting in pregnancy; consequently stress effects may be transgenerational. A multilevel approach that includes an ecological perspective may help to explain heterogeneities in asthma expression across socioeconomic and geographic boundaries that to date remain largely unexplained. Evolving studies incorporating psychological, behavioral, and physiologic correlates of stress more specifically inform underlying mechanisms operating in these critical periods of development. The role of genetics, gene by environment interactions, and epigenetic mechanisms of gene expression have been sparsely examined in epidemiologic studies on stress and asthma although overlapping evidence provides proof of concept for such studies in the future.

Host-bacteria interactions in the intestine: homeostasis to chronic inflammation

In the past decade it has become clear that the gut constitutes an important frontier of the body, which not only regulates the selective entry of nutrients while keeping vigilant against pathogens but also is largely responsible for shaping the immune response to educate the organism to recognize self from non-self. The very notion of self has undergone a dramatic change, with the acknowledgment that our 'selves' include a plethora of microbial species that actively participate in our body's homeostasis. The immune system continuously adapts to the microbiota in a cyclic, dynamic cross talk where intestinal epithelial cells play an important role in instructing noninflammatory responses for a steady-state control of bacterial growth, or triggering inflammatory mechanisms that can clear the gut from harmful invaders. The system is complex and robust in the sense that many players with partially overlapping roles act to keep the integrity of the intestinal mucosal barrier. Failure of these mechanisms involves genetic and environmental triggers and leads to inflammatory bowel disease. In this review, we seek to collect the state-of-the-art knowledge about how host and microbiota interact to promote gut homeostasis and provide evidences of malfunctioning of the described mechanisms in human inflammatory bowel disease.

Sepsis and immune response

BACKGROUND

Sepsis and secondary multiple organ failure in critically ill patients are the major cause of death, but the pathogenesis of sepsis is not clear, especially the dysfunction of the immune system. In this paper, we review the response and regulation of the immune system and the functions of a variety of inflammatory mediators in sepsis.

DATA SOURCES

Studies were identified by searching MEDLINE and PubMed for articles using the keywords "sepsis", "immune response", and "inflammatory mediator" up to October 2010. Additional papers were identified by a manual search of the references from the key articles.

RESULTS

THIS SYSTEMATIC REVIEW WAS CONDUCTED OF: 1) the immune response; 2) immune regulation; 3) inflammatory mediators; 4) high-mobility group box 1 protein; 5) the complement system; and 6) the autonomic nervous system. There are no therapeutic approaches available for sepsis that target inflammatory response; the mortality of sepsis has not been significantly reduced.

CONCLUSIONS

Sepsis is complex and dynamic, and it has a group of heterogeneous syndromes. Since different patients with sepsis have different etiology, susceptibility, and responses, treatment should be prescribed individually.

Neuropeptides as pleiotropic modulators of the immune response

Although necessary to eliminate pathogens, inflammation can lead to serious deleterious effects in the host if left unchecked. During the inflammatory response, further damage may arise from potential autoimmune responses occurring when the immune cells and molecules that respond to pathogen-derived antigens also react to self-antigens. In this sense, the identification of endogenous factors that control exacerbated immune responses is a key goal for the development of new therapeutic approaches for inflammatory and autoimmune diseases. Some neuropeptides that are produced during the ongoing inflammatory response have emerged as endogenous anti-inflammatory agents that could collaborate in tuning the balanced steady state of the immune system. These neuropeptides participate in maintaining immune tolerance through two distinct mechanisms: by regulating the balance between pro-inflammatory and anti-inflammatory factors, and by inducing the emergence of regulatory T cells with suppressive activity against autoreactive T cell effectors. Indeed, a functioning neuropeptide system contributes to general health, and alterations in the levels of these neuropeptides and/or their receptors lead to changes in susceptibility to inflammatory and autoimmune diseases. Recently, we found that some neuropeptides also have antimicrobial and antiparasitic actions, suggesting that they could act as primary mediators of innate defense, even in the most primitive organisms. In this review, we use the vasoactive intestinal peptide as example of an immunomodulatory neuropeptide to summarize the most relevant data found for other neuropeptides with similar characteristics, including adrenomedullin, urocortin, cortistatin and ghrelin.

Neuroimmune pharmacology as a component of pharmacology in medical school curriculum

An introduction to the discipline of pharmacology is a standard part of the scientific foundation of medical school curricula. Neuroimmune pharmacology is a new subtopic that integrates fundamental concepts of neuroscience, immunology, infectious disease, and pharmacology. The integration of these areas is important to medical training in view of the growing concern over neurodegenerative diseases and cognitive disorders. This article introduces a submodule and concomitant syllabus for inclusion of neuroimmune pharmacology as a component of a pharmacology curriculum. The introductory lectures of neuroimmune pharmacology will concentrate on the role of the immune system in (1) schizophrenia and major depression; (2) neurodegenerative disorders; and (3) drug addiction. Emphasis will be placed on the competencies of critical thinking, problem solving, learning interest, and effectiveness of medical students. Problem-based learning and case study discussions will also be applied.

A marked reduction in priming of cytotoxic CD8+ T cells mediated by stress-induced glucocorticoids involves multiple deficiencies in cross-presentation by dendritic cells

Protracted psychological stress elevates circulating glucocorticoids, which can suppress CD8(+) T cell-mediated immunity, but the mechanisms are incompletely understood. Dendritic cells (DCs), required for initiating CTL responses, are vulnerable to stress/corticosterone, which can contribute to diminished CTL responses. Cross-priming of CD8(+) T cells by DCs is required for initiating CTL responses against many intracellular pathogens that do not infect DCs. We examined the effects of stress/corticosterone on MHC class I (MHC I) cross-presentation and priming and show that stress/corticosterone-exposed DCs have a reduced ability to cross-present OVA and activate MHC I-OVA(257-264)-specific T cells. Using a murine model of psychological stress and OVA-loaded β(2)-microglobulin knockout "donor" cells that cannot present Ag, DCs from stressed mice induced markedly less Ag-specific CTL proliferation in a glucocorticoid receptor-dependent manner, and endogenous in vivo T cell cytolytic activity generated by cross-presented Ag was greatly diminished. These deficits in cross-presentation/priming were not due to altered Ag donation, Ag uptake (phagocytosis, receptor-mediated endocytosis, or fluid-phase uptake), or costimulatory molecule expression by DCs. However, proteasome activity in corticosterone-treated DCs or splenic DCs from stressed mice was partially suppressed, which limits formation of antigenic peptide-MHC I complexes. In addition, the lymphoid tissue-resident CD11b(-)CD24(+)CD8α(+) DC subset, which carries out cross-presentation/priming, was preferentially depleted in stressed mice. At the same time, CD11b(-)CD24(+)CD8α(-) DC precursors were increased, suggesting a block in development of CD8α(+) DCs. Therefore, glucocorticoid-induced changes in both the cellular composition of the immune system and intracellular protein degradation contribute to impaired CTL priming in stressed mice.

Morphine decreases early peritoneal innate immunity responses in Swiss-Webster and C57BL6/J mice through the inhibition of mast cell TNF-α release

OBJECTIVE

To characterize immunosuppressive effects of morphine on the early innate immunity response of cytokine production in peritoneal cavity after LPS challenge.

METHODS

The effects of a single i.p. administration of morphine (3.1 or 31 mg/kg) on LPS-induced tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein-1 (CCL2) intraperitoneal release was tested in Swiss-Webster, C57BL/6J, mast cell deficient Kit(Wsh/Wsh) (W-sh) and mast cell reconstituted (W-sh-rec) mice.

RESULTS

Morphine was found to inhibit LPS-induced TNF-α but not CCL2 release in the peritoneal cavity. Studies on mast cell deficient and reconstituted mice indicate that resident mast cells mediate selective morphine immunosuppression in the peritoneal cavity.

Major stress hormones suppress the response of macrophages through down-regulation of TLR2 and TLR4

BACKGROUND

Severe trauma often leads to diminished cytokines especially from macrophages to Toll-like receptor (TLR) agonists. However, the molecular mechanisms remain to be elucidated. As surgical trauma could also induce neuroendocrine hormones to modulate the immune system, we investigated the effects of major hormones, including endogenous glucocorticoid (corticosterone (CORT)), epinephrine (E), and norepinephrine (NE) on the expression and response of TLR2 and TLR4 in macrophages.

MATERIALS AND METHODS

Rat macrophages were pretreated by each hormone (1000 ng/mL of CORT, E, and NE) for 24 h, then restimulated with Pam3CSK4 or lipopolysaccharide (LPS) for further 24 h, and supernatant tumor necrosis factor-alpha (TNF-α) was measured. Additionally, macrophages were incubated with different concentrations of hormones (0-10,000 ng/mL) for 48 h or with 1000 ng/mL of hormones for 0-48 h, the expressions of TLR2 and TLR4 and intracellular molecules (MyD88, IRAK1, and TRAF6) in macrophages were analyzed by real-time quantitative polymerase chain reaction (PCR) and RT-PCR, respectively.

RESULTS

Pam3CSK4-stimulated TNF-α production was significantly reduced from macrophages pretreated with CORT, and both Pam3CSK4- and LPS-stimulated TNF-α were suppressed with E. Moreover, CORT down-regulated only TLR2 expression in both time- and dose-dependent manner, but both TLR2 and TLR4 mRNA expressions were down-regulated in time- and dose-dependent manner after exposure to E. However, the transcript expression of MyD88, IRAK1, and TRAF6 remained unchanged after exposure to each hormone.

CONCLUSIONS

These results suggested that the down-regulation of TLR2 and TLR4 expressions by CORT and E is involved in the hyporesponsiveness of macrophages.