Regulation of interleukin-10 production by beta-adrenergic agonists

The Interplay between Autonomic Nervous System and Inflammation across Systemic Autoimmune Diseases

The autonomic nervous system (ANS) and the immune system are deeply interrelated. The ANS regulates both innate and adaptive immunity through the sympathetic and parasympathetic branches, and an imbalance in this system can determine an altered inflammatory response as typically observed in chronic conditions such as systemic autoimmune diseases. Rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis all show a dysfunction of the ANS that is mutually related to the increase in inflammation and cardiovascular risk. Moreover, an interaction between ANS and the gut microbiota has direct effects on inflammation homeostasis. Recently vagal stimulation techniques have emerged as an unprecedented possibility to reduce ANS dysfunction, especially in chronic diseases characterized by pain and a decreased quality of life as well as in chronic inflammation.

The Long-term Effect of Dobutamine on Intrinsic Myocardial Function and Myocardial Injury in Septic Rats with Myocardial Dysfunction

ABSTRACT

Dobutamine (DOB) is recommended as an inotrope for septic patients with low cardiac output, but its long-term impact on sepsis-induced cardiomyopathy remains unclear. This study investigated the long-term effect of DOB on septic myocardial dysfunction and injury. Rats were exposed to cecal ligation and puncture (CLP), the intrinsic myocardial function, other organ functions, hemodynamics, inflammatory response, serum myocardial injury biomarkers, myocardial apoptosis, and vascular permeability were determined. At 6 h after CLP, the left ventricular ±dP/dt were significantly depressed, cardiac tumor necrosis factor-α and vascular cell adhesion molecule-1 expression were increased, but not serum cardiac troponin I (cTnI), N-terminal pro-brain natriuretic peptide (NT-proBNP), heart-type fatty acid-binding protein (H-FABP), creatinine, and urea nitrogen concentrations in CLP group compared with controls. At 9 h after CLP, hepatic dysfunction was present in CLP rats compared with controls. At 6 h after CLP, DOB treatment did not affect hemodynamics, the left ventricular ±dP/dt, cytokine levels in serum and myocardium, as well as cardiomyocyte apoptosis and cardiac vascular hyperpermeability at 20 h after CLP. However, DOB (10.0 μg/kg) increased serum IL-10 level and improved survival in septic rats. These results indicate that the intrinsic myocardial depression occurs earlier than hepatic and renal dysfunction in sepsis and serum cTnI, NT-proBNP, and H-FABP are not suitable as early biomarkers for sepsis-induced myocardial dysfunction. Although DOB treatment (10.0 μg/kg) in the presence of myocardial dysfunction improves survival in septic rats, it neither improves myocardial function and hemodynamics nor attenuates myocardial injury at the later stage of sepsis.

Microsomal prostaglandin E synthase-1 gene deletion impairs neuro-immune circuitry of the cholinergic anti-inflammatory pathway in endotoxaemic mouse spleen

The cholinergic anti-inflammatory pathway (CAP) is an innate neural reflex where parasympathetic and sympathetic nerves work jointly to control inflammation. Activation of CAP by vagus nerve stimulation (VNS) has paved way for novel therapeutic strategies in treating inflammatory diseases. Recently, we discovered that VNS mediated splenic acetylcholine (ACh) release and subsequent immunosuppression in response to LPS associated inflammation is impaired in mice lacking microsomal prostaglandin E synthase-1 (mPGES-1) expression, a key enzyme responsible for prostaglandin E2 synthesis. Here, we have further investigated the consequences of mPGES-1 deficiency on various molecular/cellular events in the spleen which is critical for the optimal functioning of VNS in endotoxaemic mice. First, VNS induced splenic norepinephrine (NE) release in both mPGES-1 (+/+) and (-/-) mice. Compared to mPGES-1 (+/+), immunomodulatory effects of NE on cytokines were strongly compromised in mPGES-1 (-/-) splenocytes. Interestingly, while LPS increased choline acetyltransferase (ChAT) protein level in mPGES-1 (+/+) splenocytes, it failed to exert similar effects in mPGES-1 (-/-) splenocytes despite unaltered β₂ AR protein expression. In addition, nicotine inhibited TNFα release by LPS activated mPGES-1 (+/+) splenocytes in vitro. However, such immunosuppressive effects of nicotine were reversed both in mPGES-1 (-/-) mouse splenocytes and human PBMC treated with mPGES-1 inhibitor. In summary, our data implicate PGE2 as an important mediator of ACh synthesis and noradrenergic/cholinergic molecular events in the spleen that constitute a crucial part of the CAP immune regulation. Our results suggest a possible link between cholinergic and PG system of CAP that may be of clinical significance in VNS treatment.

Repeated Stress Exaggerates Lipopolysaccharide-Induced Inflammatory Response in the Rat Spleen

Spleen is an immune organ innervated with sympathetic nerves which together with adrenomedullary system control splenic immune functions. However, the mechanism by which prior stress exposure modulates the immune response induced by immunogenic challenge is not sufficiently clarified. Thus, the aim of this study was to investigate the effect of a single (2 h) and repeated (2 h daily for 7 days) immobilization stress (IMO) on the innate immune response in the spleen induced by lipopolysaccharide (LPS, 100 µg/kg). LPS elevated splenic levels of norepinephrine and epinephrine, while prior IMO prevented this response. LPS did not alter de novo production of catecholamines, however, prior IMO attenuated phenylethanolamine N-methyltransferase gene expression. Particularly repeated IMO exacerbated LPS-induced down-regulation of α1B- and β1-adrenergic receptors (ARs), while enhanced α2A- and β2-AR mRNAs. Elevated expression of inflammatory mediators (iNOS2, IL-1β, IL-6, TNF-α, IL-10) was observed following LPS and repeated IMO again potentiated this effect. These changes were associated with enhanced Ly6C gene expression, a monocyte marker, and elevated MCP-1, GM-CSF, and CXCL1 mRNAs suggesting an increased recruitment of monocytes and neutrophils into the spleen. Additionally, we observed increased Bax/Bcl-1 mRNA ratio together with reduced B cell numbers in rats exposed to repeated IMO and treated with LPS but not in acutely stressed rats. Altogether, these data indicate that repeated stress via changes in CA levels and specific α- and β-AR subtypes exaggerates the inflammatory response likely by recruiting peripheral monocytes and neutrophils to the spleen, resulting in the induction of apoptosis within this tissue, particularly in B cells. These changes may alter the splenic immune functions with potentially pathological consequences.

A Promising New Approach for the Treatment of Inflammatory Pain: Transfer of Stem Cell-Derived Tyrosine Hydroxylase-Positive Cells

OBJECTIVES

The appearance of endogenous tyrosine hydroxylase-positive cells (TH+ cells) in collagen-induced arthritis was associated with an anti-inflammatory effect. Here we investigated putative anti-inflammatory and antinociceptive effects of the transfer of induced, bone marrow stem cell-derived TH+ cells (iTH+ cells) on murine antigen-induced arthritis (AIA).

METHODS

Bone marrow-derived stem cells were differentiated into iTH+ cells. These cells were transferred to mice immunized against methylated bovine serum albumin (mBSA) 2 days before AIA was induced by injection of mBSA into one knee joint. In AIA control mice and iTH+-treated mice the severity of AIA, pain-related behavior, humoral and cellular responses, and the invasion of macrophages into the dorsal root ganglia were assessed.

RESULTS

The intravenous transfer of iTH+ cells before AIA induction did not cause a sustained suppression of AIA severity but significantly reduced inflammation-evoked pain-related behavior. The iTH+ cells used for transfer exhibited enormous production of interleukin-4. A major difference between AIA control mice and iTH+-treated AIA mice was a massive invasion of the dorsal root ganglia by iNOS-negative, arginine 1-positive macrophages corresponding to an M2 phenotype. The differences in other cellular and humoral immune parameters such as release of cytokines from stimulated lymphocytes between AIA control mice and iTH+-treated mice were small.

CONCLUSIONS

The transfer of iTH+ cells may cause a long-lasting reduction of arthritis-induced pain even if it does not ameliorate inflammation. The invasion of M2 macrophages into the dorsal root ganglia is likely to be an important mechanism of antinociception.

Adrenergic Effect on Cytokine Release After Ex Vivo Healthy Volunteers' Whole Blood LPS Stimulation

Catecholamines are molecules with immunomodulatory properties in health and disease. Several studies showed the effect of catecholamines when administered to restore hemodynamic stability in septic patients. This study investigates the effect of norepinephrine and dobutamine on whole blood cytokine release after ex vivo lipopolysaccharide (LPS) stimulation. Whole blood collected from healthy individuals was stimulated with LPS, in the presence of norepinephrine or dobutamine at different concentrations, with or without metoprolol, a β1 receptor antagonist. Cytokine measurement was performed in isolated cell culture supernatants with ELISA. Results are expressed as mean ± SEM and compared with Mann-Whitney rank-sum test. Both norepinephrine and dobutamine significantly reduced TNF-α and IL-6 production after ex vivo LPS stimulation of whole blood in a dose-dependent manner, and this effect was partially reversed by the presence of metoprolol. Norepinephrine and dobutamine reduce the LPS-induced production of pro-inflammatory cytokines, thus possibly contributing to altered balance between the inflammatory and anti-inflammatory responses, which are vital for a successful host response to severe disease, shock, and sepsis.

Neuroendocrine-immune interaction: Evolutionarily conserved mechanisms that maintain allostasis in an ever-changing environment

It has now become accepted that the immune system and neuroendocrine system form an integrated part of our physiology. Immunological defense mechanisms act in concert with physiological processes like growth and reproduction, energy intake and metabolism, as well as neuronal development. Not only are psychological and environmental stressors communicated to the immune system, but also, vice versa, the immune response and adaptation to a current pathogen challenge are communicated to the entire body, including the brain, to evoke adaptive responses (e.g., fever, sickness behavior) that ensure allocation of energy to fight the pathogen. This phenomenon is evolutionarily conserved. Hence it is both interesting and important to consider the evolutionary history of this bi-directional neuroendocrine-immune communication to reveal phylogenetically ancient or relatively recently acquired mechanisms. Indeed, such considerations have already disclosed an extensive "common vocabulary" of information pathways as well as molecules and their receptors used by both the neuroendocrine and immune systems. This review focuses on the principal mechanisms of bi-directional communication and the evidence for evolutionary conservation of the important physiological pathways involved.

Review: Immunodepression in sepsis and SIRS assessed by ex vivo cytokine production is not a generalized phenomenon: a review

Sepsis and non-infectious systemic inflammatory response syndrome (SIRS) are paradoxically associated with an exacerbated production of cytokines, as assessed by their presence in biological fluids, and a diminished ability of circulating leukocytes to produce cytokine upon in vitro activation. In this review, we depict that the observed cellular hyporeactivity is not a global phenomenon and that some signalling pathways are unaltered and allow the cells to respond normally to certain stimuli. Furthermore, we illustrate that during sepsis and SIRS, cells derived from tissues are either fully responsive to ex vivo stimuli or even primed, in contrast to cells derived from hematopoietic compartments (blood, spleen, etc.) which are hyporeactive. In addition to cytokine production, nuclear factor-κB (NF-κB) status within leukocytes can be used as a useful marker of hypo- or hyper-reactivity. We illustrate that the immune-depression reported in sepsis and SIRS patients, often revealed by a diminished capacity of leukocytes to respond to lipopolysaccharide, is not a generalized phenomenon and that SIRS is associated with a compartmentalized responsiveness which involves either anergic or primed cells.

Lipopolysaccharide induces catecholamine production in mesenteric adipose tissue of rats previously exposed to immobilization stress

Catecholamines (CAs) are mainly produced by sympathoadrenal system but their de novo production has been also observed in adipose tissue cells. The aim of this work was to investigate whether immune challenge induced by lipopolysaccharide (LPS) modulates biosynthesis of CAs in mesenteric adipose tissue (MWAT), as well as whether previous exposure to immobilization (IMO) stress could modulate this process. Sprague-Dawley rats were exposed to single (2 h) or repeated (2 h/7 days) IMO and afterwards injected with LPS (i.p., 100 μg/kg body weight) and sacrificed 3 h later. LPS did not alter CA biosynthesis in MWAT in control rats. Single and repeated IMO elevated CAs and expression of CA biosynthetic enzymes in MWAT, including adipocyte and stromal/vascular fractions (SVF). Repeated IMO followed by LPS treatment led to the up-regulation of CA-biosynthetic enzymes expression, elevation of CAs in SVF but depletion of norepinephrine and epinephrine in adipocyte fraction. Prior IMO caused a marked LPS-induced macrophage infiltration in MWAT as evaluated by F4/80 expression. A positive correlation between expression of tyrosine hydroxylase and F4/80 suggests macrophages as the main source of LPS-induced CA production in MWAT. Furthermore, prior exposure to the single or repeated IMO differently affected immune responses following LPS treatment by modulation of inflammatory cytokine expression. These data suggest that stress might be a significant modulator of immune response in MWAT via stimulation of the macrophage infiltration associated with cytokine response and de novo production of CAs.

Stress-Related Immune Markers in Depression: Implications for Treatment

Major depression is a serious psychiatric disorder; however, the precise biological basis of depression still remains elusive. A large body of evidence implicates a dysregulated endocrine and inflammatory response system in the pathogenesis of depression. Despite this, given the heterogeneity of depression, not all depressed patients exhibit dysregulation of the inflammatory and endocrine systems. Evidence suggests that inflammation is associated with depression in certain subgroups of patients and that those who have experienced stressful life events such as childhood trauma or bereavement may be at greater risk of developing depression. Consequently, prolonged exposure to stress is thought to be a key trigger for the onset of a depressive episode. This review assesses the relationship between stress and the immune system, with a particular interest in the mechanisms by which stress impacts immune function, and how altered immune functioning, in turn, may lead to a feed forward cascade of multiple systems dysregulation and the subsequent manifestation of depressive symptomology. The identification of stress-related immune markers and potential avenues for advances in therapeutic intervention is vital. Changes in specific biological markers may be used to characterize or differentiate depressive subtypes or specific symptoms and may predict treatment response, in turn facilitating a more effective, targeted, and fast-acting approach to treatment.

Stroke, mTBI, infection, antibiotics and beta blockade: Connecting the dots

Several themes supported by a robust literature are addressed in this clinical translational review and research paper: (1) the inadequate standard of care for minimal traumatic brain injury (mTBI)/concussion when compared to stroke because diagnosis and care for mTBI/concussion are based primarily on a symptom only framework; (2) the treatment of stroke (brain injury) infection with select antibiotics; (3) the use of beta blockade in stroke (brain injury). The various etiologies of brain injury appear to coalesce to common endpoints: potential neuronal demise, cognitive and functional losses, immune suppression and infection. The use of principles patterned after 'Koch's Postulates' (show/prove the presence of infection/illness/disease, treat until resolved, and prove objectively that the disease/illness is gone/healed/cured) appears to be marginalized in establishing a diagnosis and recovery from mTBI/TBI. The pathways of immune system interactions in stroke (brain injury) and infection are briefly discussed. The suggestion of combined specific antibiotic and beta blockade for ischemic stroke (brain injury) and mTBI is advanced for treatment and expeditious further study. Stroke is considered a brain injury in this paper. Stroke is also considered and recommended as a study model for mTBI therapy because of their common end points from brain damage. It is suggested that potential transfer or translation of therapy for stroke may be useful in mTBI.

Elements toward novel therapeutic targeting of the adrenergic system

Adrenergic receptors belong to the family of the G protein coupled receptors that represent important targets in the modern pharmacotherapies. Studies on different physiological and pathophysiological properties of the adrenergic system have led to novel evidences and theories that suggest novel possible targeting of such system in a variety of pathologies and disorders, even beyond the classical known therapeutic possibilities. Herein, those advances have been illustrated with selected concepts and different examples. Furthermore, we illustrated the applications and the therapeutic implications that such findings and advances might have in the contexts of experimental pharmacology, therapeutics and clinic. We hope that the content of this work will guide researches devoted to the adrenergic aspects that combine neurosciences with pharmacology.

Targeting α- and β-Adrenergic Receptors Differentially Shifts Th1, Th2, and Inflammatory Cytokine Profiles in Immune Organs to Attenuate Adjuvant Arthritis

The sympathetic nervous system (SNS) regulates host defense responses and restores homeostasis. SNS-immune regulation is altered in rheumatoid arthritis (RA) and rodent models of RA, characterized by nerve remodeling in immune organs and defective adrenergic receptor (AR) signaling to immune cell targets. The SNS typically promotes or suppresses inflammation via α- and β₂-AR activation, respectively, and indirectly drives humoral immunity by blocking Th1 cytokine secretion. Here, we investigate how β₂-AR stimulation and/or α-AR blockade at disease onset affects disease pathology and cytokine profiles in relevant immune organs from male Lewis rats with adjuvant-induced arthritis (AA). Rats challenged to induce AA were treated with terbutaline (TERB), a β₂-AR agonist (600 μg/kg/day) and/or phentolamine (PHEN), an α-AR antagonist (5.0 mg/kg/day) or vehicle from disease onset through severe disease. We report that in spleen, mesenteric (MLN) and draining lymph node (DLN) cells, TERB reduces proliferation, an effect independent of IL-2. TERB also fails to shift T helper (Th) cytokines from a Th1 to Th2 profile in spleen and MLN (no effect on IFN-γ) and DLN (greater IFN-γ) cells. In splenocytes, TERB, PHEN, and co-treatment (PT) promotes an anti-inflammatory profile (greater IL-10) and lowers TNF-α (PT only). In DLN cells, drug treatments do not affect inflammatory profiles, except PT, which raised IL-10. In MLN cells, TERB or PHEN lowers MLN cell secretion of TNF-α or IL-10, respectively. Collectively, our findings indicate disrupted β₂-AR, but not α-AR signaling in AA. Aberrant β₂-AR signaling consequently derails the sympathetic regulation of lymphocyte expansion, Th cell differentiation, and inflammation in the spleen, DLNs and MLs that is required for immune system homeostasis. Importantly, this study provides potential mechanisms through which reestablished balance between α- and β₂-AR function in the immune system ameliorates inflammation and joint destruction in AA.

Autonomic regulation of cellular immune function

The nervous system and the immune system (IS) are two integrative systems that work together to detect threats and provide host defense, and to maintain/restore homeostasis. Cross-talk between the nervous system and the IS is vital for health and well-being. One of the major neural pathways responsible for regulating host defense against injury and foreign antigens and pathogens is the sympathetic nervous system (SNS). Stimulation of adrenergic receptors (ARs) on immune cells regulates immune cell development, survival, proliferative capacity, circulation, trafficking for immune surveillance and recruitment, and directs the cell surface expression of molecules and cytokine production important for cell-to-cell interactions necessary for a coordinated immune response. Finally, AR stimulation of effector immune cells regulates the activational state of immune cells and modulates their functional capacity. This review focuses on our current understanding of the role of the SNS in regulating host defense and immune homeostasis. SNS regulation of IS functioning is a critical link to the development and exacerbation of chronic immune-mediated diseases. However, there are many mechanisms that need to be further unraveled in order to develop sound treatment strategies that act on neural-immune interaction to resolve or prevent chronic inflammatory diseases, and to improve health and quality of life.

Divergent neuroendocrine responses to localized and systemic inflammation

The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS can provide negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. However, inflammation and infection can also directly regulate SNS function by peripheral actions on postganglionic cells. The present review discusses how inflammation activates autonomic reflex pathways and compares the effect of localized and systemic inflammation on ACCs and postganglionic sympathetic neurons. Systemic inflammation significantly enhanced catecholamine secretion through an increase in Ca(2+) release from the endoplasmic reticulum. In contrast, acute and chronic GI inflammation reduced voltage-gated Ca(2+) current. Thus it appears that the mechanisms underlying the effects of peripheral and systemic inflammation neuroendocrine function converge on the modulation of intracellular Ca(2+) signaling.

Neuroendocrine modulation of the inflammatory response in common carp: adrenaline regulates leukocyte profile and activity

Inflammatory responses have to be carefully controlled, as high concentrations and/or prolonged action of inflammation-related molecules (e.g. reactive oxygen species, nitric oxide and pro-inflammatory cytokines) can be detrimental to host tissue and organs. One of the potential regulators of the inflammatory process are stress mediators including adrenaline. In vivo effects of adrenaline were studied during zymosan-induced (Z) peritoneal inflammation in the common carp Cyprinus carpio L. Adrenaline injected together with zymosan (ZA) did not change the number of inflammatory leukocytes in the peritoneal cavity, however at 24h post-injection it significantly reduced the percentage of monocytes/macrophages. Moreover, compared to cells retrieved from fish treated with PBS or zymosan only, adrenaline increased the percentage of apoptotic leukocytes in the focus of inflammation. Furthermore, adrenaline significantly reduced the expression of chemokine CXCL8_L1 (a functional homolog of mammalian IL-8) and its receptors (CXCR1 and CXCR2), indicating changes in leukocyte recruitment after stress. We conclude that adrenaline may contribute to a coordinated reaction by influencing the inflammatory response via direct regulation of leukocyte migration and/or apoptosis.

Adrenergic regulation of the innate immune response in common carp (Cyprinus carpio L.)

Catecholamines exert their physiological actions through α and β adrenergic receptors (ARs). As ARs are not exclusively expressed on neuroendocrine cells, but also on leukocytes, they may facilitate neuroendocrine modulation of immune responses. We sequenced the β(2a)-AR in common carp, and studied its expression profile and involvement in the regulation of teleost innate immune responses. β(2a)-AR messenger RNA was found to be constitutively expressed in brain areas, especially in the preoptic nucleus (NPO, homologous to the mammalian hypothalamus), and in immune organs. During the active phase of an in vivo inflammatory response, induced by i.p. zymosan treatment, β(2a)-AR gene expression was up-regulated in the peritoneal leukocytes. Additionally, adrenaline in vitro reduced the synthesis of oxygen radical species and nitric oxide, while it enhanced arginase activity in fish phagocytes. Furthermore, in vitro adrenaline administration inhibited expression of pro-inflammatory cytokines, chemokines and their receptors. It is therefore hypothesized that adrenaline will down-regulate phagocyte skewing toward classical/innate polarization.

Chronic cold stress in mice induces a regulatory phenotype in macrophages: correlation with increased 11β-hydroxysteroid dehydrogenase expression

Susceptibility to infections, autoimmune disorders and tumor progression is strongly influenced by the activity of the endocrine and nervous systems in response to a stressful stimulus. When the adaptive system is switched on and off efficiently, the body is able to recover from the stress imposed. However, when the system is activated repeatedly or the activity is sustained, as during chronic or excessive stress, an allostatic load is generated, which can lead to disease over long periods of time. We investigated the effects of chronic cold stress in BALB/c mice (4°C/4 h daily for 7 days) on functions of macrophages. We found that chronic cold stress induced a regulatory phenotype in macrophages, characterized by diminished phagocytic ability, decreased TNF-α and IL-6 and increased IL-10 production. In addition, resting macrophages from mice exposed to cold stress stimulated spleen cells to produce regulatory cytokines, and an immunosuppressive state that impaired stressed mice to control Trypanosoma cruzi proliferation. These regulatory effects correlated with an increase in macrophage expression of 11β-hydroxysteroid dehydrogenase, an enzyme that converts inactive glucocorticoid into its active form. As stress is a common aspect of modern life and plays a role in the etiology of many diseases, the results of this study are important for improving knowledge regarding the neuro-immune-endocrine interactions that occur during stress and to highlight the role of macrophages in the immunosuppression induced by chronic stress.

Chronic propranolol treatment affects expression of adrenoceptors on peritoneal macrophages and their ability to produce hydrogen peroxide and nitric oxide

Using both immunocytochemical and flow cytometric analyses of rat peritoneal exudate cells constitutive expression of tyrosine hydroxylase and both beta(2)- and alpha(1)- adrenoceptors on macrophages was revealed. Furthermore, according to the characteristic assemblage of tyrosine hydroxylase and adrenoceptor subtype expression different macrophage subsets were identified. In vitro treatment of macrophages with the non-selective alpha,beta-adrenoceptor agonist arterenol and/or the beta-adrenoceptor antagonist propranolol indicated that beta-adrenoceptors potentiated nitric oxide (NO) production and suggested alpha-adrenoceptor-mediated suppression of hydrogen peroxide (H(2)O(2)) production. An increase in H(2)O(2) production in the presence of the alpha(1)-adrenoceptor antagonist ebrantil provided support for this. Chronic propranolol treatment in vivo led to increased NO and H(2)O(2) production by peritoneal macrophages. Furthermore, this treatment resulted in opposing effects on the expression of beta(2)- and alpha(1)-adrenoceptors on peritoneal macrophages (a stimulatory effect on beta(2)-adrenoceptors and a suppressive effect on alpha(1)-adrenoceptors). In conclusion, a subset of resident peritoneal macrophages synthesizes catecholamines, which may exert differential effects on H(2)O(2) and NO production via distinct adrenoceptors. Finally, chronic propranolol treatment affected adrenoceptor expression on peritoneal macrophages and altered their capacity to generate NO and H(2)O(2).

Synergistic IL-10 induction by LPS and the ceramide-1-phosphate analog PCERA-1 is mediated by the cAMP and p38 MAP kinase pathways

Expression of the anti-inflammatory cytokine IL-10 can be induced either by TLR agonists such as lipopolysaccharide (LPS), or by various endogenous stimuli, in particular those acting via a cAMP-dependent signaling pathway. We have previously reported that the synthetic phospho-ceramide analogue-1 (PCERA-1) increases cAMP level and subsequently down-regulates production of TNFalpha and up-regulates production of IL-10 in LPS-stimulated macrophages. The objective of this study was to determine the mechanism of activity of PCERA-1 and the role of cAMP in LPS-induced IL-10 production. We show here that PCERA-1 induces IL-10 production in synergism with various TLR agonists in mouse RAW264.7 macrophages. Cooperativity is evident both at the mRNA and protein levels. IL-10 production by LPS and PCERA-1 is mediated by the cAMP pathway and by the p38 MAP kinase. Phosphorylation of p38 is cooperatively accomplished by LPS and PCERA-1 or other cAMP inducers. Furthermore, the activity of PCERA-1 can be partially mimicked by a cell-permeable analog of cAMP, and blocked by the protein kinase A (PKA) inhibitor H89. Finally, in the absence of PCERA-1, the residual IL-10 induction by LPS depends on the basal cAMP level as it can be largely elevated by the phosphodiesterase (PDE)-4 inhibitor rolipram. Our results thus indicate that IL-10 induction by LPS critically depends on basal cAMP level, and that a co-stimulus by a TLR agonist and a cAMP-elevating agent results in synergistic PKA-dependent and p38-dependent IL-10 production.

Protective effect of decursinol on mouse models of sepsis: enhancement of interleukin-10

The effects of decursinol on various models of sepsis were investigated. Intra-peritoneal pretreatment of mice with various doses of decursinol (1~100 mg/kg) effectively suppressed lethality induced in three mouse models of experimental sepsis, i.e., lipopolysaccharide (LPS)/D-galactosamine (GalN), high-dose LPS (20 mg/kg), and cecal ligation and puncture (CLP). Intra-peritoneal pretreatment of mice with decursinol (50 mg/kg) markedly enhanced the LPS/GalN-induced increase of plasma interleukin-10 (IL-10) levels, without affecting plasma TNF-alpha, IL-6 and IL-12 levels. These results suggest that decursinol could be effective for prevention or treatment of sepsis.

Sympathetic modulation of immunity: relevance to disease

Optimal host defense against pathogens requires cross-talk between the nervous and immune systems. This paper reviews sympathetic-immune interaction, one major communication pathway, and its importance for health and disease. Sympathetic innervation of primary and secondary immune organs is described, as well as evidence for neurotransmission with cells of the immune system as targets. Most research thus far has focused on neural-immune modulation in secondary lymphoid organs, has revealed complex sympathetic modulation resulting in both potentiation and inhibition of immune functions. SNS-immune interaction may enhance immune readiness during disease- or injury-induced 'fight' responses. Research also indicate that dysregulation of the SNS can significantly affect the progression of immune-mediated diseases. However, a better understanding of neural-immune interactions is needed to develop strategies for treatment of immune-mediated diseases that are designed to return homeostasis and restore normal functioning neural-immune networks.

Role of nonsynaptic communication in regulating the immune response

The discovery of nonsynaptic communication in the 1960s and 1970s was an important milestone in investigating the function of the nervous system, and it revolutionized our view about information transmission between neurons. In addition, nonsynaptic communication has a practical importance not only within the nervous system, but in the communication between the peripheral nervous system and other organ systems. Nonsynaptic communication takes place in different immune organs, which are innervated by sympathetic nerve terminals. In addition, the function of microglia, one of the immunocompetent cell types of the brain, can also be affected by neurotransmitters released from axon varicosities. The various functions of immune cells are modulated by released neurotransmitters without any direct synaptic contact between nerve endings and targeted immune cells requiring only functional neurotransmitter receptors on immune cells. Here, we briefly overview the role of the various receptor subtypes mediating nonsynaptic modulation of the function of immunocompetent cells both in the periphery and in the central nervous system.

Review: Brain—immune communication psychoneuroimmunology of multiple sclerosis

The central nervous system (CNS) and the immune system are two extremely complex and highly adaptive systems. In the face of a real or anticipated threat, be it physical (eg, infection) or psychological (eg, psychosocial stress) in nature, the two systems act in concert to provide optimal adaptation to the demanding internal or environmental conditions. During instances of well being, the communication between these two systems is well tuned and balanced. However, a disturbed crosstalk between the CNS and the immune system is thought to play a major role in a wide series of disorders characterized by a hyporesponsive or hyperresponsive immune system. In multiple sclerosis (MS), a chronic inflammatory and neurodegenerative disease, an excess of inflammatory processes seems to be a hallmark and there is growing evidence for a disturbed communication between the CNS and the immune system as a crucial pathogenic factor. While the exact mechanisms for these phenomena are still poorly understood, the young discipline of psychoneuroimmunology (PNI), which focuses on the mechanism underlying the brain to immune crosstalk, might offer some insights into the existing pathogenic mechanisms. Findings from the field of PNI might also help to gain a better understanding regarding the origin and course of MS clinical symptoms such as fatigue and depression.

Dual ligand stimulation of RAW 264.7 cells uncovers feedback mechanisms that regulate TLR-mediated gene expression

To characterize how signaling by TLR ligands can be modulated by non-TLR ligands, murine RAW 264.7 cells were treated with LPS, IFN-gamma, 2-methyl-thio-ATP (2MA), PGE(2), and isoproterenol (ISO). Ligands were applied individually and in combination with LPS, for 1, 2, and 4 h, and transcriptional changes were measured using customized oligo arrays. We used nonadditive transcriptional responses to dual ligands (responses that were reproducibly greater or less than the expected additive responses) as a measure of pathway interaction. Our analysis suggests that cross-talk is limited; <24% of the features with significant responses to the single ligands responded nonadditively to a dual ligand pair. PGE(2) and ISO mainly attenuated, while 2MA enhanced, LPS-induced transcriptional changes. IFN-gamma and LPS cross-regulated the transcriptional response induced by each other: while LPS preferentially enhanced IFN-gamma-induced changes in gene expression at 1 h, IFN-gamma signaling primarily attenuated LPS-induced changes at 4 h. Our data suggest specific cross-talk mechanisms: 1) LPS enhances the expression of IFN-gamma-response genes by augmenting STAT1 activity and by activating NF-kappaB, which synergizes with IFN-gamma-induced transcriptional factors; 2) IFN-gamma attenuates the late LPS transcriptional response by increasing the expression of suppressor of cytokine signaling 1 and cytokine-inducible SH2-containing protein expression; 3) 2MA modulates LPS secondary transcriptional response by increasing IFN-beta and inhibiting IL-10 gene expression; 4) PGE(2) and ISO similarly regulate the LPS transcriptional response. They increase IL-10 transcription, resulting in attenuated expression of known IL-10-suppressed genes.

Integrating systems biology and medical imaging: understanding disease distribution in the lung model

OBJECTIVE

Many chronic diseases exhibit characteristic pulmonary distribution patterns, but the underlying biologic explanations remain elusive. On the basis of emerging evidence from systems biology, we propose that gradients of T helper immune function exist as an epiphenomenon of the hypoxic pulmonary vasoconstriction response. Regional variation of immune function may contribute to preferential distribution patterning of lung diseases.

CONCLUSION

The lungs represent but one example in which the distribution of immune function throughout the body may explain disease location. This hypothetic framework can apply to diseases outside the realm of pulmonary biology and illustrates the potential benefit of integrating advances in systems biology and medical imaging.

Adenosine A2A agonists in development for the treatment of inflammation

Extracellular adenosine binds specifically to a family of four G protein-coupled cell-surface adenosine receptors (ARs). As the activation of the A2AAR modulates the activity of multiple inflammatory cells including neutrophils, macrophages and T lymphocytes, the receptor is considered to be a promising pharmacological target for the treatment of inflammatory disorders. Although adenosine binds nonselectively to all four AR subtypes, A2AAR selective agonists have been developed and shown to inhibit multiple manifestations of inflammatory cell activation including superoxide anion generation, cytokine production and adhesion molecule expression. A2AAR agonists are also vasodilators, but the inhibition of inflammation occurs at low doses that produce few or no cardiovascular side effects. Therefore, the selective activation of the A2AAR by these compounds holds significant potential in the treatment of inflammation.

Can thromboembolism be the result, rather than the inciting cause, of acute vascular events such as stroke, pulmonary embolism, mesenteric ischemia, and venous thrombosis?: a maladaptation of the prehistoric trauma response

Thromboembolism is considered the inciting cause of many vascular disorders including acute coronary syndrome (ACS), ischemic stroke, pulmonary embolism (PE), deep vein thrombosis (DVT), and mesenteric ischemia. Adrenergia and inflammation are known to accompany these conditions, particularly among arterial thromboembolic disorders, but the teleologic basis of these associations remains poorly understood. We argue that thromboembolism may sometimes be the result, rather than the cause, of acute vascular events, and may be precipitated by underlying adrenergia. Thromboembolic events are most prone to occur during parts of the circadian, seasonal, lifespan, and reproductive cycles with sympathetic dominance, as well as during behavioral, exertional, physiologic, and iatrogenic activation of sympathetic stress. Molecular evidence suggests that adrenergia and inflammation can promote coagulation and lead to co-activation of the pathways. Acute vascular events that occur without angiographic evidence of occlusion suggest that some infarcts may be attributable to adrenergia alone. "Embolic" disorders may represent asynchronous systemic phenomena rather than clot migration. During acute thromboembolism, downstream tissue hypoxia can activate maladaptive self-propelling cycles of sympathetic bias, inflammation, and coagulation. The counterproductive co-activation of these pathways may reflect a maladaptive interlink forged during the primordial evolution of trauma physiology. Their rapid co-mobilization enables rapid control of hemorrhage, microbial defense, and perfusion maintenance during trauma, but the pathways may behave maladaptively in the setting of modern diseases where endothelial injury may be more often precipitated by smoking, diabetes, dyslipidemia, or hypertension. Sympathetic blockade is already employed in ACS, and beta-blockers are used as antihypertensives to prevent stroke. Our hypothesis suggests that the benefits of beta-blockers in stroke may be independent of antihypertensive effects, and that adrenergia may represent a target for managing all thromboembolic disorders, independent of anti-coagulative and thrombolytic therapies. Perhaps reducing adrenergia, rather than maintaining high cerebral perfusion pressure, may represent a counterintuitive strategy for treating stroke and for reducing reperfusion injury. Plausible mechanisms by which autonomic dysfunction may induce venous thrombosis are discussed, especially in those with baroreceptor dysfunction, immobilization, or dehydration. Unexplained hypercoagulability of cancer may also operate through tumor-induced adrenergia and inflammation.

Antiinflammatory effects of salmeterol after inhalation of lipopolysaccharide by healthy volunteers

RATIONALE

Salmeterol is a beta2-adrenoreceptor agonist used in the treatment of obstructive pulmonary disease. Salmeterol inhibits inflammatory responses by neutrophils and mononuclear cells in vitro and in mouse models of lung inflammation in vivo.

OBJECTIVE

To determine the effect of salmeterol on LPS-induced lung inflammation in humans.

METHODS

Thirty-two healthy subjects were enrolled in a single-blinded, placebo-controlled study. Subjects inhaled 100 microg salmeterol or placebo (t=-0.5 h) followed by 100 microg LPS or normal saline (t=0 h; n=8/group). Measurements were performed in bronchoalveolar lavage fluid and purified alveolar macrophages obtained 6 h post-challenge.

MEASUREMENTS AND MAIN RESULTS

Inhalation of LPS was associated with neutrophil influx, neutrophil degranulation (myeloperoxidase, bactericidal/permeability-increasing protein and elastase), release of cytokines (tumor necrosis factor alpha and interleukin 6) and chemokines (interleukin 8, epithelial cell-derived neutrophil attractant 78, macrophage inflammatory proteins 1alpha and 1beta), activation of alveolar macrophages (upregulation of HLA-DR and CD71; enhanced expression of mRNAs for 13 different mediators of inflammation), and protein leakage (all p<0.05 vs. placebo/saline). Pretreatment with salmeterol inhibited LPS-induced neutrophil influx, neutrophil degranulation (myeloperoxidase), tumor necrosis factor alpha release, and HLA-DR expression (all p<0.05 vs. placebo/LPS), while not significantly influencing other responses.

CONCLUSION

Salmeterol exerts antiinflammatory effects in the pulmonary compartment of humans exposed to LPS.

Modulation of host immunity by HIV may be partly achieved through usurping host autonomic functions

Modulation of host immunity has been observed in human immunodeficiency virus (HIV) infections. HIV is believed to influence host immunity through a variety of mechanisms including direct effects on host T cell survival, indirect effects on cytokine profile through modulation of immune cells, and modulation of endocrine functions that affect immunity such as steroids. We hypothesize that HIV infection may also alter host immunity through modulation of host sympatho-vagal balance. Specifically, we propose that HIV drives autonomic balance towards sympathetic bias, which can contribute to a T helper (Th)2 type immunity. A variety of paraviral syndromes associated with HIV infection such as QT prolongation, cachexia, cardiomyopathy, and lipodystrophy are consistent with evidence of autonomic dysfunction. Immunomodulatory effects of autonomic dysfunction toward Th2 bias are presented. A plausible mechanism by which HIV can influence autonomic balance through hypothalamic manipulation is offered. Shift to Th2 dominance is associated with HIV disease progression and can be viewed as a viral adaptation to promote its own survival. Autonomic remodeling by HIV may exemplify this phenomenon. Our hypothesis has implications for treatment of HIV and its associated syndromes.

Caffeine suppresses TNF-alpha production via activation of the cyclic AMP/protein kinase A pathway

This study investigated the effect of in vitro exposure to caffeine, and its major metabolite paraxanthine, at concentrations relevant to typical caffeine consumption in humans, on lipopolysaccharide (LPS)-stimulated cytokine production in human whole blood. In addition, a role for the cyclic AMP/protein kinase A (PKA) pathway in the immunomodulatory effect of caffeine was investigated. Diluted whole blood (taken following >/=15 h abstinence from caffeine-containing food and beverages) was preincubated with caffeine or paraxanthine (10-100 microM) and stimulated with LPS (1 proportional, variant g/ml) for 24 h. The proinflammatory cytokines tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-12, and the antiinflammatory cytokine IL-10 were measured in cell-free supernatants. Whilst caffeine and paraxanthine had little or no effect on IL-10, IL-1beta, or IL-12 production, TNF-alpha production was suppressed in all individuals studied. The effect was statistically significant at 100 microM and consistent across seven experiments performed. Although not statistically significant, a similar effect was observed with paraxanthine. Caffeine (100 microM) also increased intracellular cyclic AMP concentrations in LPS-stimulated monocytes isolated from whole blood. Moreover, the effect of caffeine on TNF-alpha production was abolished by pretreatment with the protein kinase A inhibitor Rp-8-Br-cAMPS (10(-4) and 10(-5)M). To conclude, this study demonstrates that concentrations of caffeine that are relevant to human consumption consistently suppress production of the proinflammatory cytokine TNF-alpha in human blood and that this effect is mediated by the cyclic AMP/protein kinase A pathway.

Autonomic dysfunction may be an under-recognized cause of female fertility disorders

Female conditions of impaired fertility comprise a heterogeneous group of disorders that are attributed to various anatomic, hormonal and immunologic disturbances. We hypothesize that autonomic dysfunction may be a previously unrecognized factor in female fertility disorders. Emerging physiologic and molecular evidence suggests that autonomic balance varies during normal menstrual cycles with a shift to sympathetic bias during the luteal phase. Furthermore, many diseases associated with autonomic dysfunction show catamenial variations in patterns consistent with a shift to sympathetic bias occurs during the second half of normal menstrual cycles. The shift to sympathetic bias during the normal luteal phase may be an evolutionary adaptation to address the immunologic and physiologic demands for successful implantation and gestation. Through direct modulation of the lymphoid system and activation of the cortisol pathway, sympathetic bias promotes a shift to relative T helper (Th)-2 biased immunity which may favor maternal tolerance of the embryo by attenuating Th-1 mediated interference of implantation. Indeed, a growing body of evidence has implicated abnormal Th balance in fertility disorders, but the link has been attributed to factors other than autonomic function, such as hormonal factors. After implantation, maternal sympathetic bias may further support gestation through physiologic changes necessary to maintain placental perfusion pressure. We propose that insufficient shift to sympathetic bias during the luteal phase, which manifests in inadequate shift towards Th-2 bias and down-regulation of Th-1 function, may be the mechanism of impaired fertility in certain patients. Our hypothesis portends new potential methods to treat fertility disorders by modulating autonomic balance.

Adrenergic modulation of cytokine release in bone marrow progenitor-derived macrophage following polymicrobial sepsis

Catecholamines may impact on the pathophysiology of sepsis by attenuating proinflammatory cytokine and augmenting antiinflammatory cytokine production by macrophages. We tested this premise in bone marrow monocyte progenitor-derived macrophages. Polymicrobial sepsis was induced in mice through cecal ligation and puncture. ER-MP 12 monocyte progenitors were isolated and differentiated into macrophages in vitro 72 hr later. Lipopolysaccharide (LPS)-stimulated cytokine production was measured with and without epinephrine, IL-10 and anti-IL-10 antibody. Epinephrine significantly increased IL-10 production, but attenuated TNF-alpha release exclusively through beta2 adrenergic receptors, and is independent of IL-10 production. Together, these results suggest that epinephrine can promote a potent antiinflammatory response in sepsis.

“Starve a fever and feed a cold”: feeding and anorexia may be adaptive behavioral modulators of autonomic and T helper balance

Anorexia is a common symptom accompanying infections, but the teleology of the phenomenon remains unexplained. We hypothesize that anorexia may represent a prehistoric behavioral adaptation to fight infection by maintaining T helper (Th)2 bias, which is particularly vital in fighting bacterial pathogens. Specifically, we propose that anorexia may avert the reduction of Th2/Th1 ratio by preventing feeding-induced neurohormonal and vagal output from the gut. Emerging evidence suggests that the vagal and neurohormonal output of the gut during feeding promotes Th1 function, which is desirable in fighting viral infections. Since fever may be an adaptation to fight bacteria and "colds" are generally viral in origin, the adage "starve a fever and feed a cold" may reflect a sensible behavioral strategy to tilt autonomic and Th balance in directions that are optimal for fighting the particular type of infection. The ability to modulate T helper balance through the neurohormonal and autonomic axis by adjusting food intake may be the mechanism behind other unexplained clinical observations such as the improved outcomes of ICU patients after enteric versus parenteric feedings. Compared to the prehistoric period when bacterial infection was commonplace, the anorexic response may be less adaptive today when viruses and cancers have become common triggers of anorexia. By promoting host anorexia, cachexia, and insomnia, cancers and viruses can deter behaviors such as digestion and sleep that would raise vagal and Th1 activity against tumors and viruses. Hydration and sleep, unexplained but widely accepted recommendations for flu patients, may also work by promoting vagal and Th1 functions. Modulating feeding, hydration, and sleep may prove beneficial in treating other conditions associated with abnormal autonomic and Th balance.

Acute coronary syndromes and heart failure may reflect maladaptations of trauma physiology that was shaped during pre-modern evolution

We hypothesize that the pathophysiology of many cardiovascular diseases reflects a maladaptation of the triad of trauma response: adrenergia, inflammation, and coagulation. During biologic evolution, trauma has likely been a prevailing factor in natural selection. Components of the trauma triad act to limit hemorrhage, defend wounds against microorganisms, and initiate reconstruction. Response pathways that enable survival after trauma confer obvious adaptive advantages especially if the individual goes on to reproduce. Modern humans have shaped their own ecologic environment in such a way that the incidence of trauma has waned and previously unseen pathologies have emerged. Manifestations of modern diet, changing lifestyles, and extended lifespan have suddenly created new pathologic challenges to our prehistoric physiologic system. During our evolutionary heritage, endothelial injury and end-organ hypoxia were likely exclusively associated with physical trauma and the responses of the trauma triad were appropriate. Today, endothelial injury is more often precipitated by distinctly modern stressors such as hypertension, smoking, diabetes, and dyslipidemia. The once-adaptive trauma response can maladaptively initiate dangerous, self-propelling cycles of adrenergia, inflammation, and coagulation. Acute coronary syndromes perhaps best exemplify this phenomenon. Congestive heart failure, which often ensues, can similarly be seen as a maladaptation of the trauma triad. Whereas end-organ hypoxia was once commonly associated with trauma, now hypoxia is more often attributable to distinctly modern stressors such as pump failure. The fluid conservation and inflammation that results from the trauma triad was clearly adaptive in our prehistoric past, but in congestive heart failure the response is maladaptive, engendering self-propelling exacerbations of pump failure and vascular disease. Our maladaptive trauma response hypothesis portends new diagnostic and therapeutic paradigms for cardiovascular diseases and has ramifications for many other conditions such as stroke, venous thrombosis, vasculitis, aortic disease, arterial disease, pulmonary embolism, and restenosis.

Acute stress suppresses pro-inflammatory cytokines TNF-alpha and IL-1 beta independent of a catecholamine-driven increase in IL-10 production

Interleukin (IL)-10 is an anti-inflammatory cytokine that can down-regulate various aspects of the immune response. In this study we demonstrate that exposure to a psychophysiological stressor (swim stress) increases IL-10 production in female rats in response to an in vivo challenge with bacterial lipopolysaccharide (LPS). This increase in LPS-induced IL-10 was associated with suppression of the pro-inflammatory cytokines IL-1beta and TNF-alpha, indicating that overall, swim stress promotes an immunosuppressive cytokine phenotype. Despite the well-documented ability of IL-10 to suppress pro-inflammatory cytokine production, neutralisation of IL-10 failed to block the stress-induced suppression of IL-1beta and TNF-alpha. These data indicate that the suppressive effect of swim stress on these pro-inflammatory cytokines occurs independently of increased IL-10 production. To determine if swim stress-induced immunosuppression was mediated by increased sympathetic nervous system activity, and subsequent beta-adrenoceptor activation, we assessed the ability of the beta-adrenoceptor antagonist nadolol to block stressor-induced changes in cytokine production. Whilst pre-treatment with nadolol completely blocked the stress-induced increase in IL-10, it failed to alter the suppression of TNF-alpha or IL-1beta. Similarly, pre-treatment with the glucocorticoid receptor antagonist mifepristone also failed to attenuate the suppressive effect of swim stress on IL-1beta and TNF-alpha production. These data indicate that neither increased glucocorticoid secretion, nor catecholamine-induced beta-adrenoceptor activation, mediates the suppressive effect of swim stress on pro-inflammatory cytokine production. Taken together, these data demonstrate a role for beta-adrenoceptor activation in the ability of acute swim stress to increase LPS-induced IL-10 production, and also highlight a mechanistic dissociation between the ability of swim stress to increase IL-10 and suppress pro-inflammatory cytokine production.

Tissue specific effects of the beta 2-adrenergic agonist salbutamol on LPS-induced IFN-gamma, IL-10 and TGF-beta responses in vivo

Beta2-adrenergic agonists have immunomodulatory effects both in vitro and in vivo. We describe that oral salbutamol (beta-adrenergic agonist) administration has tissue-specific effects on cytokine production induced by intraperitoneal (i.p.) lipopolysaccharide (LPS) administration. Salbutamol reduced LPS-induced IFN-gamma levels at both mucosal and non-mucosal sites. However, salbutamol increased IL-10 levels in the peritoneal cavity, but decreased levels in terminal ileum and lung. Salbutamol did not alter LPS-induced TGF-beta levels in the terminal ileum, but increased levels in liver and peritoneal cavity. Thus, orally administered salbutamol decreases LPS-induced IFN-gamma levels in all tissues tested, but has tissue specific effects on IL-10 and TGF-beta levels.

Decrease of interleukin-10-producing T cells in the peripheral blood of severe unstable atopic asthmatics

BACKGROUND

Although IL-10 is known as an immunoregulatory cytokine produced by various cells including T cells, its basic profile in atopic asthma remains uncertain.

OBJECTIVE

The profiles of IL-10 production in circulating CD4+ T cells of atopic asthmatics were investigated with respect to clinical severity.

METHODS

Forty atopic asthmatics were divided into three groups: mild, and severe but stable and severe unstable asthmatics. Eosinophils were counted in the peripheral blood and sputum, and exhaled nitric oxide was assessed. PBMCs were stimulated with or without anti-CD3 and anti-CD28 antibodies and then processed for detecting IL-10-producing CD4+ cells using flow cytometry.

RESULTS

There was no difference in the eosinophil count in blood or sputum and in nitric oxide level among the three groups. IL-10-producing CD4+ cells were mainly detected in a CD45RO+ memory population. The frequency of IL-10-producing cells after stimulation was significantly lower in the severe unstable group compared to the mild group. In addition, the frequency of IL-10-producing cells in the severe unstable group was significantly lower than that in the severe stable group despite the fact that both groups received similar treatments with high-dose inhaled corticosteroids. The IL-10 production of CD4+CD45RO+ cells in response to dexamethasone did not differ among the three groups.

CONCLUSIONS

IL-10-producing CD4+CD45RO+ cells in the peripheral blood are decreased in severe unstable asthmatics, which is not explained by the effect of high-dose inhaled corticosteroid medication.

Autonomic dysregulation as a basis of cardiovascular, endocrine, and inflammatory disturbances associated with obstructive sleep apnea and other conditions of chronic hypoxia, hypercapnia, and acidosis

Obstructive sleep apnea has traditionally been viewed as a structural disease. A multitude of systemic endocrine and cardiovascular abnormalities have been previously attributed to the prevalence of obesity in these patients. A growing body of clinical evidence, however, points to a relationship between sleep apnea and its systemic abnormalities independent of obesity. We hypothesize that this association is based on a maladaptive autonomic response of chemoreceptors, reacting to the hypoxia, hypercapnia, and acidosis of sleep apnea. The elevated sympathetic response triggers an inflammatory cascade that results in a myriad of downstream consequences including insulin resistance, hypertension, diabetes, atherosclerosis and metabolic syndrome. The sympathetic bias and endocrine disturbances may further exacerbate sleep disturbance in a potentially pernicious cycle. Our proposal may extend to any chronic respiratory or metabolic conditions that manifest hypoxia, hypercapnia, and acidosis and elicit a maladaptive autonomic and inflammatory response.

Adrenergic modulation of splenic macrophage cytokine release in polymicrobial sepsis

Enhanced adrenergic stimulation and catecholamine release are important components of the pathophysiology of sepsis. Under physiological conditions, adrenergic stimulation has been shown to be a negative regulator of proinflammatory cytokine production through increasing IL-10 production. Here we have investigated if adrenergic stimulation similarly inhibits TNF-alpha and IL-6 production by splenic macrophages isolated from a polymicrobial sepsis model. Male B(6)D(2)F(1) mice were subjected to sham (S), laparotomy (Lap), and cecal ligation and puncture (CLP) under anesthesia. Splenic macrophages were isolated 72 h after the initial injury and were stimulated with endotoxin (LPS) in the presence and absence of epinephrine. Compared with S and Lap, splenic macrophages from the CLP group produced significantly less TNF-alpha and IL-6 and more IL-10 when stimulated with LPS. Macrophage cultures from CLP animals incubated with either epinephrine or IL-10 for 2 h had significantly reduced TNF-alpha and IL-6 release in response to LPS. However, similar cultures pretreated with IL-10 antibody before the addition of exogenous epinephrine failed to reverse the attenuation of LPS-stimulated cytokines. Pretreatment of macrophage cultures with beta(2)- (ICI-118551) but not beta(1)-adrenergic (atenolol) receptor antagonists reversed the epinephrine-mediated cytokine attenuation following LPS treatment. Data are also presented that demonstrate the involvement of protein kinase A activation with adrenergic agonist but not with IL-10 stimulation. Taken together, these findings suggest that adrenergic mechanisms may influence peripheral tissue macrophage inflammatory cytokine response following trauma and sepsis, independent of the effects of IL-10.

Salmeterol, a beta2-receptor agonist, attenuates lipopolysaccharide-induced lung inflammation in mice

Lipopolysaccharide is ubiquitously present in the environment. To determine the effect of salmeterol, a long-acting beta(2)-receptor agonist, on lipopolysaccharide-induced lung inflammation, mice received lipopolysaccharide (10 microg) intranasally with or without salmeterol intraperitoneally (5 mg/kg) 30 min earlier and 12 h thereafter. Salmeterol dose- and time-dependently inhibited the lipopolysaccharide-induced influx of neutrophils into bronchoalveolar lavage fluid and lung tissue, and these pulmonary neutrophils displayed a reduced expression of CD11b at their surface. To determine the contribution of the salmeterol effect on neutrophil CD11b in the attenuated neutrophil recruitment, we treated mice intranasally exposed to lipopolysaccharide with salmeterol with or without a blocking anti-CD11b antibody. Anti-CD11b profoundly reduced lipopolysaccharide-induced neutrophil influx in bronchoalveolar lavage fluid, an effect that was modestly enhanced by concurrent salmeterol treatment. These data suggest that salmeterol inhibits lipopolysaccharide-induced neutrophil recruitment to the lungs by a mechanism that possibly in part is mediated by an effect on neutrophil CD11b.

Immunomodulatory function of seminal catecholamines may be an adaptation for reproduction

Catecholamines are found at high concentrations in seminal fluid. The exact functional significance of seminal catecholamines is unknown. We hypothesize that seminal catecholamines perform important immunomodulatory functions that support reproductive success. Specifically, we propose that catecholamines contribute to a local adaptive shift of T helper (Th) balance to Th2 dominance in the maternal reproductive tract to enable the gametes, and possibly the nascent zygote, to evade immune surveillance of the female. Our hypothesis suggests that the Th2 effects of catecholamines are independent of the direct immunomodulatory effects of seminal cytokines such as prostaglandin E2 and transforming growth factor beta1. Potential immunomodulatory functions of other seminal constituents such as aldosterone, oxytocin, vasopressin, and angiotensin remain unexplored and represents a topic of future interest. Seminal stress hormones may play a role in mating dynamics since alpha males typically live in a state of high hormonal stress, Mating with adrenalized alpha males may represent an adaptive Darwinian strategy by females to maximize their reproductive fitness.

Tumors may modulate host immunity partly through hypoxia-induced sympathetic bias

Hypoxia can occur in solid tumors when oxygen demand from rapid tumor growth outstrips the blood supply. Once thought to be merely a consequence of tumor physiology, more recent evidence suggests that hypoxia may also be a tumor adaptation to promote its own survival. For example, hypoxic conditions generate local transcriptional changes that enhance angiogenesis and glycolysis, processes that directly promote tumor growth. We hypothesize that maladaptive local chemoreceptor host response to hypoxia may contribute to a shift in immune balance that favors cancer survival. Specifically, we propose that hypoxia in the tumor microenvironment activates local adrenergic activity which in turn inhibits Th1 function while favoring Th2 function. Th1 function is vital to the host defense against cancer, and Th1 depletion is associated with increased cancer risk. In our view, the sympathetic bias induces Th2 bias independent of the direct immunomodulatory effects of tumor-derived cytokines. The hypoxia-induced local adrenergic response may be part of a broad tumor adaptation that enables its evasion of host immune surveillance. That the host response of Th2 bias is so reflexively linked to hypoxia may reflect the likelihood that trauma, rather than modern diseases such as cancer, were the most common causes of hypoxia during our teleologic past when natural selection shaped our biologic pathways. Validation of our hypothesis may shed more light on the biology of cancer and reveal novel diagnostic and therapeutic strategies.