Vagus nerve stimulation attenuates the systemic inflammatory response to endotoxin

Fat meets the cholinergic antiinflammatory pathway

The cholinergic antiinflammatory pathway is a neural mechanism that is controlled by the vagus nerve and inhibits local cytokine release, thereby preventing the damaging effects of cytokine overproduction. A new study now shows that dietary fat can activate this pathway, a finding that may help explain the immune system's failure to react to food antigens and commensal bacteria. Here we discuss this new data and its potential implications for dietary intervention in the treatment of inflammatory diseases.

Dobutamine does not influence inflammatory pathways during human endotoxemia*

OBJECTIVE

Catecholamines have anti-inflammatory and anticoagulant properties. Dobutamine is a synthetic catecholamine frequently used in patients with septic myocardial dysfunction. The objective was to determine whether a continuous infusion of dobutamine exerts immunomodulatory effects in healthy volunteers challenged with endotoxin.

DESIGN

Prospective, open-label study.

SETTING

Clinical research unit of a university hospital.

PARTICIPANTS

Sixteen male healthy volunteers.

INTERVENTIONS

Volunteers received a constant infusion with dobutamine (10 microg.kg.min, n = 8) or physiologic saline (n = 8). All participants were challenged with a bolus injection of endotoxin prepared from Escherichia coli (4 ng/kg). Dobutamine infusion was commenced 1 hr before endotoxin challenge and was continued until 3 hrs thereafter.

MEASUREMENTS AND MAIN RESULTS

Dobutamine infusion was associated with an increase in mean arterial blood pressure (peak 122 +/- 5 mm Hg) and heart rate (peak 84 +/- 4 beats/min, both p < .05 vs. saline). Endotoxin injection induced the systemic release of cytokines (tumor necrosis factor-alpha, interleukins-6, -8, and -10) and secretory phospholipase A2, endothelial cell activation (increase in the plasma levels of soluble E-selectin and von Willebrand factor), activation of coagulation (increased plasma levels of soluble tissue factor, F1 + 2 prothrombin fragment, and thrombin-antithrombin complexes), and activation with subsequent inhibition of fibrinolysis (increased plasma concentrations of tissue-type plasminogen activator, plasminogen activator inhibitor type I, and plasmin-alpha2-antiplasmin complexes). None of these responses were influenced by dobutamine.

CONCLUSIONS

Dobutamine, infused in a clinically relevant dose, does not influence inflammatory and coagulant pathways during human endotoxemia.

Activation of the cholinergic anti-inflammatory pathway reduces NF-kappab activation, blunts TNF-alpha production, and protects againts splanchic artery occlusion shock

The cholinergic anti-inflammatory pathway has not yet been studied in splanchnic artery occlusion (SAO) shock. We investigated whether electrical stimulation (STIM) of efferent vagus nerves suppresses the inflammatory cascade in SAO shock. Animals were subjected to clamping of the splanchnic arteries for 45 min, followed by reperfusion. This surgical procedure resulted in an irreversible state of shock (SAO shock). Sham-operated animals were used as controls. Two minutes before the start of reperfusion, rats were subjected to bilateral cervical vagotomy (VGX) or sham surgical procedures. Application of constant voltage pulses to the caudal vagus ends (STIM: 5 V, 2 ms, 6 Hz for 15 min, 5 min after the beginning of reperfusion) increased survival rate (VGX + SAO + Sham STIM = 0% at 4 h of reperfusion; VGX + SAO + STIM = 90% at 4 h of reperfusion), reverted the marked hypotension, inhibited IkappaBalpha liver loss, blunted the augmented nuclear factor-kappaB activity, decreased hepatic tumor necrosis factor (TNF)-alpha mRNA (VGX + SAO + Sham STIM = 1.0 +/- 1.9 TNF-alpha/glyceraldehyde-3-phosphate dehydrogenase ratio; VGX + SAO + STIM = 0.3 +/- 0.2 TNF-alpha/glyceraldehyde-3-phosphate dehydrogenase ratio), reduced plasma TNF-alpha (VGX + SAO + Sham STIM = 118 +/- 19 pg/mL; VGX + SAO + STIM = 39 +/- 8 pg/mL), ameliorated leukopenia, and decreased leukocyte accumulation, as revealed by means of myeloperoxidase activity in the ileum (VGX + SAO + Sham STIM = 7.9 +/- 1 U/g tissue; VGX + SAO + STIM = 3.1 +/- 0.7 U/g tissue) and in the lung (VGX + SAO + Sham STIM = 8.0 +/- 1.0 U/g tissue; VGX + SAO + STIM = 3.2 +/- 0.6 U/g tissue). Chlorisondamine, a nicotinic receptor antagonist, abated the effects of vagal stimulation. Our results show a parasympathetic inhibition of nuclear factor-kappaB and TNF-alpha in SAO shock.

The vagus nerve and nicotinic receptors modulate experimental pancreatitis severity in mice

BACKGROUND & AIMS

The nervous system, through the vagus nerve, controls inflammation by decreasing the release of tumor necrosis factor-alpha from endotoxin stimulated macrophages. This anti-inflammatory effect is mediated by an interaction of acetylcholine, the principal neurotransmitter of the vagus nerve, with macrophage cholinergic nicotinic receptors expressing the alpha7 subunit.

METHODS

To determine the role of this "nicotinic anti-inflammatory pathway" in experimental pancreatitis, we induced pancreatitis in mice by 12 hourly intraperitoneal injections of cerulein. Pancreatitis was preceded by unilateral left cervical vagotomy or pretreatment with the nicotinic receptor antagonist mecamylamine or by pretreatment with the selective alpha7 nicotinic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21).

RESULTS

Vagotomy or pretreatment with mecamylamine resulted in an enhanced severity of pancreatitis, as reflected by histology, edema, plasma hydrolases, and interleukin-6 levels. Furthermore, the number of neutrophils migrated to the pancreas was increased in these mice, as shown by myeloperoxidase content and intrapancreatic staining of neutrophils. Conversely, GTS-21 pretreatment strongly decreased the severity of pancreatitis. Pancreatitis-associated pulmonary inflammation was independent of the integrity of the vagus nerve and nicotinic receptors.

CONCLUSIONS

This study provides the first evidence for a therapeutic potential of the vagus nerve and the "nicotinic anti-inflammatory pathway" in attenuating inflammation and injury during experimental pancreatitis.

Pulmonary neuroendocrine cells, airway innervation, and smooth muscle are altered in Cftr null mice

The amine- and peptide-producing pulmonary neuroendocrine cells (PNEC) are widely distributed within the airway mucosa of mammalian lung as solitary cells and innervated clusters, neuroepithelial bodies (NEB), which function as airway O2 sensors. These cells express Cftr and hence could play a role in the pathophysiology of cystic fibrosis (CF) lung disease. We performed confocal microscopy and morphometric analysis on lung sections from Cftr-/- (null), Cftr+/+, and Cftr+/- (control) mice at developmental stages E20, P5, P9, and P30 to determine the distribution, frequency, and innervation of PNEC/NEB, innervation and cell mass of airway smooth muscle, and neuromuscular junctions using synaptic vesicle protein 2, smooth muscle actin, and synaptophysin markers, respectively. The mean number of PNEC/NEB in Cftr-/- mice was significantly reduced compared with control mice at E20, whereas comparable or increased numbers were observed postnatally. NEB cells in Cftr null mice showed a significant reduction in intracorpuscular nerve endings compared with control mice, which is consistent with an intrinsic abnormality of the PNEC system. The airways of Cftr-/- mice showed reduced density (approximately 20-30%) of smooth muscle innervation, decreased mean airway smooth muscle mass (approximately 35%), and reduced density (approximately 20%) of nerve endings compared with control mice. We conclude that the airways of Cftr-/- mice exhibit heretofore unappreciated structural alterations affecting cellular and neural components of the PNEC system and airway smooth muscle and its innervation resulting in blunted O2 sensing and reduced airway tonus. Cftr could play a role in the development of the PNEC system, lung innervation, and airway smooth muscle.

General anesthesia delays the inflammatory response and increases survival for mice with endotoxic shock

Anesthesia is an indispensable component of any operative procedure. In this study, we demonstrate that continuous isoflurane anesthesia for 1 h after a lethal dose (20 mg/kg of body weight) of Escherichia coli lipopolysaccharide (LPS) results in a significant increase in survival of C57BL/6J (B6) mice in comparison with survival of nonanesthetized mice. Protection by anesthesia correlates with a delay in plasma LPS circulation, resulting in a delayed inflammatory response, particularly DNA binding activity of NF-kappaB and serum levels of tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-10. Disparate classes of anesthetic agents produce the same effects on the inflammatory response, which is also independent of the inbred mouse strain used. These results suggest that anesthesia has an important impact on the outcome from endotoxemia. Moreover, the immunomodulatory effects of anesthetics should be considered when interpreting data from experimental animal models.

Prognostic impact of autonomic information flow in multiple organ dysfunction syndrome patients

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is the sequential failure of several organ systems after a trigger event, like cardiogenic shock or decompensated heart failure. Mortality is high, up to 70%. Autonomic dysfunction (AD) may substantially contribute to the development of MODS. In cardiology, it has recently been shown that nonlinear parameters could predict mortality. Our study aimed at 1. characterising the complex characteristics of AD of critically ill MODS patients by the nonlinear parameters of autonomic information flow (AIF), 2. comparing AIF with autonomic function of healthy controls, and 3. characterising the accuracy of this parameter in predicting mortality in MODS.

METHODS

We enrolled 43 score-defined MODS patients who were consecutively admitted to a twelve-bed medical intensive care unit in a university centre into this prospective outcome study. Additionally, we assigned 50 healthy controls to the study. AIF was assessed as a complexity function of AD using 24-h ECG. Measures of AIF were introduced according to the standard HRV concept. The patients were followed up for 28-day mortality.

RESULTS

MODS causes a disorganisation of short term AIF in favour of an enhanced (rigid) long term AIF. Concerning prognosis increased short term AIF was associated with survival. Short term AIF discriminated between MODS survivors and non-survivors at the level of APACHE II score.

CONCLUSIONS

This is the first study providing evidence that complex AD of MODS patients is specifically assessed by AIF time scales and that AIF has significant prognostic impact.

The acetylcholinesterase inhibitor, Donepezil, regulates a Th2 bias in Alzheimer's disease patients

The increased pro-inflammatory cytokine production was previously observed in Alzheimer's disease (AD). We sought to explore whether acetylcholinesterase inhibitor (AChEI) therapy ameliorates clinical symptoms in AD through down-regulation of inflammation. Expression and release of monocyte chemotactic protein-1 (MCP-1), a positive regulator of Th2 differentiation, and interleukin (IL)-4, an anti-inflammatory cytokine from peripheral blood mononuclear cells (PBMC) in AD patients, were investigated. PBMC were purified from AD patients at time of enrollment (T0) and after 1 month of treatment with AChEI (T1) and from healthy controls (HC). Supernatants were analyzed for cytokine levels by ELISA methods. mRNA expression were determined by RT-PCR. Expression and production of MCP-1 and IL-4 were significantly increased in AD subjects under therapy with the AChEI Donepezil, compared to the same AD patients at time of enrollment (P < 0.001). Our data suggest another possible explanation for the ability of Donepezil [diethyl(3,5-di-ter-butyl-4-hydroxybenzyl)phosphonate] to delay the progression of AD; in fact, Donepezil may modulate MCP-1 and IL-4 production, which may reflect a general shift towards type Th0/Th2 cytokines which could be protective in AD disease. The different amounts of MCP-1 and IL-4 observed might reflect the different states of activation and/or responsiveness of PBMC, that in AD patients could be kept in an activated state by pro-inflammatory cytokines.

Smoking and tuberculosis: the epidemiological association and immunopathogenesis

There is increasing evidence of a link between tuberculosis and smoking. This paper reviews the epidemiological evidence from the UK, China, India and the USA, summarizing some of the main papers which indicate an association. Where an association has been found there seems to be an increase in tuberculosis case rates of between two- and four-fold for those smoking in excess of 20 cigarettes a day, but it may be difficult to control for other factors, particularly alcohol consumption. The final part of the paper reviews possible mechanisms. A likely possibility is that nicotine turns off the production of TNF-alpha by the macrophages in the lungs, rendering the patient more susceptible to the development of progressive disease from latent Mycobacterium tuberculosis infection.

Systemic capsaicin inhibits neuronal activation in the brainstem during postoperative ileus in the mouse

INTRODUCTION

Neuronal inhibitory reflex mechanisms contribute to postoperative ileus after abdominal surgery. During this condition, sensory neurons in the brainstem are activated. We aimed to determine the contribution of capsaicin-sensitive afferents to central vagal sensitivity in mice during postoperative ileus.

MATERIALS AND METHODS

Under enflurane anesthesia, C57BL/6 mice were laparotomized and the small bowel was manipulated to induce ileus or was left untouched as a sham-treatment group. A subgroup of ileus animals was pre-treated with Capsaicin (1 microm/kg, i.p.) 48 h before small bowel manipulation. The animals were killed 24 h later and the brainstem was removed for Fos immunohistochemistry, which was quantified in the nucleus of the solitary tract (nTS). Spontaneous jejunal motility was recorded in vitro. Leukocyte infiltration in the intestinal muscularis was studied by myeloperoxidase staining as an index of postoperative inflammation.

RESULTS

There were 30+/-9 Fos-positive neurons counted in the nTS after ileus and 6+/-2 in sham controls (Bregma -7.70 mm, P=0.01). A reduction to 8+/-3 was observed after Capsaicin pre-treatment in ileus animals (P<0.05). Peak amplitudes of spontaneous jejunal motility were 2+/-0.3 cmH2O during postoperative ileus, 3+/-0.6 cmH2O after ileus with capsaicin pre-treatment, and 10+/-2 cmH2O in control animals (N=6, both P<0.05). The number of leukocytes infiltrating the muscularis was 39+/-9/mm2 during ileus and 1.8+/-1/mm2 in controls (mean+/-SEM, P<0.01, N=6). After capsaicin, this number increased to 72+/-28/mm2 in ileus animals (P<0.05 vs control animals, N=7).

CONCLUSION

The inhibition of capsaicin-sensitive vagal afferent pathways appears to boost rather than to attenuate the inflammatory response during postoperative ileus, while intestinal motility remained unchanged. This suggests a protective role of the capsaicin-sensitive afferent innervation for the inflammatory phase of postoperative ileus.

The vagal nerve as a link between the nervous and immune system in the instance of polymicrobial sepsis

BACKGROUND

The role of the vagal nerve in the autonomic nervous system is widely well known. Recently, an additional function was revealed serving as a connector between the nervous and immune system. This connection is called the "cholinergic inflammatory pathway." Through stimulation of the acetylcholine receptors located upon the macrophages, the "unspecific" immune system can be directly influenced.

METHODS

The vagal nerve was completely transected directly posterior to its passage through the diaphragm. The effect of complete vagotomy was analyzed using a murine model of polymicrobial peritonitis (colon ascendens stent peritonitis, CASP). Survival and clinical course of vagotomized or sham-operated mice were analyzed in the CASP model.

RESULTS

After CASP surgery, vagotomy led to a significantly increased mortality (64.7%) in comparison to sham-vagotomized animals (34%). No difference in the bacterial load of various tissues (lung, liver, spleen, blood, lavage fluid, and kidney) from septic animals with or without vagotomy was observed. Vagotomized animals reveal elevated serum cytokine levels (TNF, IL-6, IL-10, and MCP-1) 20 h after the induction of polymicrobial peritonitis.

CONCLUSION

The vagal nerve is therefore an important modulator of the immune system.

Central muscarinic cholinergic regulation of the systemic inflammatory response during endotoxemia

TNF has a critical mediator role in inflammation and is an important therapeutic target. We recently discovered that TNF production is regulated by neural signals through the vagus nerve. Activation of this "cholinergic antiinflammatory pathway" inhibits the production of TNF and other cytokines and protects animals from the inflammatory damage caused by endotoxemia and severe sepsis. Here, we describe a role for central muscarinic acetylcholine receptors in the activation of the cholinergic antiinflammatory pathway. Central muscarinic cholinergic activation by muscarine, the M1 receptor agonist McN-A-343, and the M2 receptor antagonist methoctramine inhibited serum TNF levels significantly during endotoxemia. Centrally administered methoctramine stimulated vagus-nerve activity measured by changes in instantaneous heart-rate variability. Blockade of peripheral muscarinic receptors did not abolish antiinflammatory signaling through the vagus nerve, indicating that peripheral muscarinic receptors on immune cells are not required for the cytokine-regulating activities of the cholinergic antiinflammatory pathway. The role of central muscarinic receptors in activating the cholinergic antiinflammatory pathway is of interest for the use of centrally acting muscarinic cholinergic enhancers as antiinflammatory agents.

A scarlet pimpernel for the resolution of inflammation? The role of supra-therapeutic doses of cobalamin, in the treatment of systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, and septic or traumatic shock

Cobalamin carrier proteins,the Transcobalamins (TCS), are elevated during trauma, infections and chronic inflammatory conditions. This remains un-explained. It is proposed that such TC elevations signal a need for cobalamin central to the resolution of inflammation. Thus Cobalamin may regulate the transcription factor, NFkappaB, activation or suppression of which determines the inflammatory response and its resolution. Such regulation may involve at least 5 separate mechanisms: (i) hormone-like regulation of TNFalpha, through reduction of excess NO by cobalamin, as well as through the selective inhibition, in tandem with glutathione, of inducible nitric oxide synthase; (ii) quenching of nitric oxide radicals and reactive oxygen species, enhanced by cobalamin's glutathione sparing effect; (iii) the promotion of acetylcholine synthesis, central to the neuro-immune cholinergic anti-inflammatory pathway; (iv) the promotion of oxidative phosphorylation; (v) and a bacteriostatic role of the TCS released by neutrophil secondary granules during phagocytosis, which also appears to modulate the inflammatory response. TC elevations are dependent on NFkappaB activation, through crosstalk between NFkappaB and Sp1, another member of the helix-loop-helix protein family, which directly mediates transcription of the TCII gene. Sp1 also has binding sites on the TNFalpha and EGF gene promoters. NFkappaB may thus ensure sufficient cobalamin to determine its own eventual suppression. Cobalamin's established regulation of EGF may additionally preserve normal function of macrophages and the coagulation cascade in wound healing. By regulating NFkappaB, Cobalamin may also be the as yet unidentified mediator needed to potentiate the anti-inflammatory action of eicosanoids derived from omega-3 essential fatty acids. Moreover, animal and human clinical data suggests that high dose cobalamin may prove a promising approach to SIRS/sepsis/septic and traumatic shock.

Enteric nervous system

PURPOSE OF REVIEW

Our aim was to provide a synopsis of how the field of enteric neurobiology has advanced during the past year.

RECENT FINDINGS

With such a large number of studies to choose from and given our emphasis in last year's issue on developmental aspects of the enteric nervous system, we have focused on several key themes reflecting the current interest in the way the enteric nervous system is altered in disease.

SUMMARY

The new basic science information gathered during the past year provides insight into pathophysiological processes and will pave the way for improved understanding of both organic and 'functional' gastrointestinal disorders.

Activation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system during inflammation and altered programming of the neuroendocrine-immune axis during fetal and neonatal development: lessons learned from the model inflammagen, lipopolysaccharide

The hypothalamic-pituitary-adrenal axis (HPAA) and autonomic nervous system (ANS) are both activated during inflammation as an elaborate multi-directional communication pathway designed to restore homeostasis, in part, by regulating the inflammatory and subsequent immune response. During fetal and neonatal development programming of the HPAA, ANS and possibly the immune system is influenced by signals from the surrounding environment, as part of an adaptive mechanism to enhance the survival of the offspring. It is currently hypothesized that if this programming is either misguided, or the individual's environment is drastically altered such that neuroendocrine programming becomes maladaptive, it may contribute to the pathogenesis of certain diseases. Current research, suggests that exposure to inflammatory signals during critical windows of early life development may influence the programming of various genes within the neuroendocrine-immune axis. This review will provide, (1) an overview of the HPAA and ANS pathways that are activated during inflammation, highlighting studies that have used lipopolysaccharide as a model inflammagen and, (2) evidence to support the hypothesis that inflammatory stress during fetal and neonatal development can alter programming of the neuroendocrine-immune axis, influencing stress and immune responsiveness, and possibly disease resistance later in life.

Hydrolytic and nonenzymatic functions of acetylcholinesterase comodulate hemopoietic stress responses

Glucocorticoid-initiated granulocytosis, excessive proliferation of granulocytes, persists after cortisol levels are lowered, suggesting the involvement of additional stress mediator(s). In this study, we report that the stress-induced acetylcholinesterase variant, AChE-R, and its cleavable, cell-penetrating C-terminal peptide, ARP, facilitate granulocytosis. In postdelivery patients, AChE-R-expressing granulocyte counts increased concomitantly with serum cortisol and AChE activity levels, yet persisted after cortisol had declined. Ex vivo, mononuclear cells of adult peripheral blood responded to synthetic ARP26 by overproduction of hemopoietically active proinflammatory cytokines (e.g., IL-6, IL-10, and TNF-alpha). Physiologically relevant ARP26)levels promoted AChE gene expression and induced the expansion of cultured CD34+ progenitors and granulocyte maturation more effectively than cortisol, suggesting autoregulatory prolongation of ARP effects. In vivo, transgenic mice overexpressing human AChE-R, unlike matched controls, showed enhanced expression of the myelopoietic transcription factor PU.1 and maintained a stable granulocytic state following bacterial LPS exposure. AChE-R accumulation and the consequent inflammatory consequences can thus modulate immune responses to stress stimuli.

Protection of early phase hepatic ischemia-reperfusion injury by cholinergic agonists

BACKGROUND

Cytokine production is critical in ischemia/reperfusion (IR) injury. Acetylcholine binds to macrophages and inhibits cytokine synthesis, through the cholinergic anti-inflammatory pathway. This study examined the role of the cholinergic pathway in cytokine production and hepatic IR- injury.

METHODS

Adult male mice underwent 90-min of partial liver ischemia followed by reperfusion. The AChR agonists (1,1-dimethyl-4-phenyl-L-pioperazinium-iodide [DMPP], and nicotine) or saline-vehicle were administered i.p. before ischemia. Plasma cytokine tumor necrosis factor (TNF)-alpha, macrophage inflammatory protein-2, and Interleukin-6 were measured. Liver injury was assessed by plasma alanine transaminase (ALT) and liver histopathology.

RESULTS

A reperfusion time-dependent hepatocellular injury occurred as was indicated by increased plasma-ALT and histopathology. The injury was associated with marked elevation of plasma cytokines/chemokines. Pre-ischemic treatment of mice with DMPP or nicotine significantly decreased plasma-ALT and cytokines after 3 h of reperfusion. After 6 h of reperfusion, the protective effect of DMPP decreased and reached a negligible level by 24 h of reperfusion, despite significantly low levels of plasma cytokines. Histopathology showed markedly diminished hepatocellular injury in DMPP- and nicotine-pretreated mice during the early-phase of hepatic-IR, which reached a level comparable to saline-treated mice at late-phase of IR.

CONCLUSION

Pharmacological modulation of the cholinergic pathway provides a means to modulate cytokine production and to delay IR-induced heaptocellular injury.

Expression and production of two selected beta-chemokines in peripheral blood mononuclear cells from patients with Alzheimer's disease

MCP-1 and RANTES are molecules that regulate monocyte and T-lymphocyte recruitment towards sites of inflammation. We sought to evaluate the role of these chemokines in Alzheimer's disease (AD), and the effect of acetylcholinesterase inhibitor (AchEI) therapy on their release from peripheral blood mononuclear cells (PBMC). MCP-1 and RANTES mRNA expressions were determined by RT-PCR and the amount of secreted chemokines was assayed using specific ELISA methods from purified PBMC from each AD patients (n = 40) at the time of enrolment (T0) and after 1 month of treatment with AchEI (T1) and from 20 healthy age and sex-matched subjects (HC). We found that expression and production of MCP-1 in AD patients was significantly lower than in HC subjects. After 1 month of therapy with AchEI (Donepezil), MCP-1 levels increased in each patient. However, higher levels were detected for RANTES in AD patients compared to control subjects and in AD patients treated with Donepezil. MCP-1 and RANTES have a compensatory role in balancing the impaired mechanisms involved in immune response during ageing. Our present findings suggest that these two chemokines are both involved in AD pathogenesis and might reflect different states of activation and/or responsiveness of PBMC from AD patients, contributing to the impaired of the peripheral immune system in these patients.

Control by cholinergic mechanisms

In the respiratory tract acetylcholine is neurotransmitter in ganglia and postganglionic parasympathetic nerves, but in addition is paracrine mediator released from various non-neuronal cells. Almost every cell type present in the respiratory tract expresses nicotinic and muscarinic receptors and therefore appears to be a target for acetylcholine. The present review describes the mechanisms of synthesis and release of acetylcholine from neuronal and non-neuronal cells and the differential control mechanisms. The different cholinoceptors, multiple nicotinic and muscarinic receptors and their signalling are outlined and their involvement in the modulation of the function of various target cells, smooth muscles, nerves, surface epithelial, secretory cells, fibroblasts and inflammatory cells is discussed in detail.

Effect of neostigmine on organ injury in murine endotoxemia: missing facts about the cholinergic antiinflammatory pathway

Electrical and pharmacologic stimulation of the efferent cholinergic antiinflammatory pathway suppress the systemic inflammatory response and can prevent lethal endotoxemia. Neostigmine, a cholinergic agent, has not been tested to determine if it can prevent histopathologic organ injury in endotoxemia. In the present study, the effects of neostigmine treatment on the histopathologic organ injury inflicted by Escherichia coli endotoxin in a mouse model of septic shock was investigated. Endotoxemia in mice caused weight loss and increased spleen, liver, and lung weight. When the organs were examined for histopathologic injury, endotoxemia increased interstitial inflammation in the lungs, liver injury, and organ injury in general terms; neostigmine, at a dose of 0.1 mg/kg, failed to attenuate these effects. Although the simultaneous administration of neostigmine at a dose of 0.3 mg/kg and endotoxin decreased interstitial inflammation in the lungs, vacuolar degeneration in the liver, and total liver injury, mortality was increased with this dose in the presence of endotoxemia. We conclude that neostigmine at a dose of 0.1 mg/kg was not protective against histopathologic organ injury in mice with endotoxemia, and a higher dose (0.3 mg/kg) was not tolerated probably owing to nonspecific parasympathetic action including cardiovascular effects. Further studies are required to determine the contribution of sites in the cholinergic antiinflammatory pathway.

Proinflammatory cytokines and leptin are increased in serum of prepubertal obese children

It has not yet been shown in prepubertal children how cytokines, leptin, and body mass, as well as parameters of obesity are interrelated. The aim of this study was to explore the relation between circulating levels of some cytokines with leptin and body mass index. A case control study was carried out in obese children of both sexes. An obese group was carried out with 63 school prepubertal children and a control group comprised the same number of nonobese children paired by age and by sex. Mean serum leptin concentration was significantly higher in the obese children at 19.9 ± 7.4 ng/mL, than the control group (7.9 ± 5.1 ng/mL). Serum IL-1β, IL-6, and TNF-α levels were also significantly higher in the obese group than controls (33.0 ± 8.9, 45.2 ± 11.8, and 9.2 ± 2.3 pg/mL, versus 3.6 ± 1.0, 13.1 ± 3.9, and 3.9 ± 1.0 pg/mL, resp). In controversy, serum IL-2 level was diminished in the obese group as 0.4 ± 0.1 versus 0.9 ± 0.1 U/L. Obesity may be a low-grade systemic inflammatory disease. Obese prepubertal children have elevated serum levels of IL-1β, IL-6, and TNF-α which are known as markers of inflammation.

Cytokines and Escherichia coli Sepsis

This review reviews the critical role played by cytokines in the pathogenesis of Escherichia coli sepsis. It focuses on prototypic pro-inflammatory and anti-inflammatory cytokines and their influence on mortality in experimental animal models of E. coli endotoxemia and of live E. coli sepsis. The review reviews the results of clinical trials on anticytokine therapy in patients with severe sepsis or septic shock. The recognition of the critical role played by tumor necrosis factor (TNF), a secreted 17kDa cytokine, in endotoxic and gram-negative shock has been a major step forward in our understanding of the pathogenesis of sepsis. The review describes the role of TNF, IL1, and IL6 in animal models of E. coli endotoxemia and sepsis. Given the pivotal role played by TNF in experimental sepsis and the fact that elevated concentrations of TNF were detected in the circulation of patients with sepsis, anti-TNF treatment strategies were investigated as adjunctive therapy for severe sepsis and septic shock. Several studies demonstrated that high levels of interleukin-6 (IL-6) are associated with an increased risk for fatal outcome. Gamma interferon (IFN-γ), IL-12, and IL-18 are functionally related cytokines. A recent study has indicated that transgenic mice overexpressing IL-15 are resistant to an otherwise lethal intraperitoneal E. coli challenge. IL4, IL10, and IL13are prototypic anti-inflammatory cytokines. Their classification as anti-inflammatory cytokines is based on the observation that these molecules inhibit the production of proinflammatory cytokines (primarily TNF and IL1) and toxic oxygen and reactive nitrogen species by myeloid cells.

Spinal Manipulative Therapy Reduces Inflammatory Cytokines but Not Substance P Production in Normal Subjects

OBJECTIVE

To examine the effect of a single spinal manipulation therapy (SMT) on the in vitro production of inflammatory cytokines, tumor necrosis factor alpha, and interleukin (IL) 1beta, in relation to the systemic (in vivo) levels of neurotransmitter substance P (SP).

METHODS

Sixty-four asymptomatic subjects were assigned to SMT, sham manipulation, or venipuncture control group. SMT subjects received a single adjustment in the thoracic spine. Blood and serum samples were obtained from subjects before and then at 20 minutes and 2 hours after intervention. Whole-blood cultures were activated with lipopolysaccharide (LPS) for 24 hours. Cytokine production in culture supernatants and serum SP levels were assessed by specific immunoassays.

RESULTS

Over the study period, a significant proportion (P </= .05) of sham and control subjects demonstrated progressive increases in the synthesis of tumor necrosis factor alpha and IL-1beta. Conversely, in a comparable proportion of cultures from SMT-derived subjects, the production of both cytokines decreased gradually. Normalization of the observed alterations to reflect the changes relative to self-baselines demonstrated that, within 2 hours after intervention, the production of both cytokines increased significantly (P < .001 to .05) in both controls. In contrast, a significant (P < .001 to .05) reduction of proinflammatory cytokine secretion was observed in cultures from SMT-receiving subjects. In all study groups, serum levels of SP remained unaltered within 2 hours after intervention.

CONCLUSIONS

SMT-treated subjects show a time-dependent attenuation of LPS-induced production of the inflammatory cytokines unrelated to systemic levels of SP. This suggests SMT-related down-regulation of inflammatory-type responses via a central yet unknown mechanism.

Microglial control of neuronal death and synaptic properties

Microglia have long been characterized by their immune function in the nervous system and are still mainly considered in a beneficial versus detrimental dialectic. However a review of literature enables to shed novel lights on microglial function under physiological conditions. It is now relevant to position these cells as full time partners of neuronal function and more specifically of synaptogenesis and developmental apoptosis. Indeed, microglia can actively control neuronal death. It has actually been shown in retina that microglial nerve growth factor (NGF) is necessary for the developmental apoptosis to occur. Similarly, in cerebellum, microglia induces developmental Purkinje cells death through respiratory burst. Furthermore, in spinal cord, microglial TNFalpha commits motoneurons to a neurotrophic dependent developmental apoptosis. Microglia can also control synaptogenesis. This is suggested by the fact that a mutation in KARAP/DAP12, a key protein of microglial activation impacts synaptic functions in hippocampus, and synapses protein content. In addition it has been now demonstrated that microglial brain-derived neurotrophin factor (BDNF) directly regulates synaptic properties in spinal cord. In conclusion, microglia can control neuronal function under physiological conditions and it is known that neuronal activity reciprocally controls microglial activation. We will discuss the importance of this cross-talk which allows microglia to orchestrate the balance between synaptogenesis and neuronal death occurring during development or injuries.

Does stress exacerbate liver diseases?

Although anecdotal comments on detrimental effects of psychosocial stress on liver diseases can be found even in the early literature, only recently has scientific evidence been reported. The present article reviewed such evidence to demonstrate how stress exacerbates liver diseases. A search of the literature from the last two decades was performed using MEDLINE by pairing 'psychological stress' with 'liver' or 'hepatitis.' Additional research was conducted by screening the bibliographies of articles retrieved in the MEDLINE search. The search results showed that the principal effectors of the activated hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, can exert a facilitative effect on the hepatic inflammatory response and even increase the risk of developing hepatocellular carcinoma. For certain liver diseases, defective HPA axis activation, which probably contributed to the exacerbation of the liver disease, has been reported. The efferent sympathetic/adrenomedullary system mainly contributes to the stress-induced exacerbation of liver diseases via its neurotransmitters, the catecholamines. In contrast, the efferent parasympathetic nervous system elicits an inhibitory effect on the development of hepatic inflammation. In conclusion, the pathophysiological interaction between stress and the liver appears to be regulated by the complex, dynamic networks of both the endocrine and autonomic nervous systems, which implies a further need for basic research into the involved mechanisms and for clinical evidence to apply psychosocial support to patients with chronic liver diseases.

Hypothalamic integration of immune function and metabolism

The immune and neuroendocrine systems are closely involved in the regulation of metabolism at peripheral and central hypothalamic levels. In both physiological (meals) and pathological (infections, traumas and tumors) conditions immune cells are activated responding with the release of cytokines and other immune mediators (afferent signals). In the hypothalamus (central integration), cytokines influence metabolism by acting on nucleus involved in feeding and homeostasis regulation leading to the acute phase response (efferent signals) aimed to maintain the body integrity. Peripheral administration of cytokines, inoculation of tumor and induction of infection alter, by means of cytokine action, the normal pattern of food intake affecting meal size and meal number suggesting that cytokines acted differentially on specific hypothalamic neurons. The effect of cytokines-related cancer anorexia is also exerted peripherally. Increase plasma concentrations of insulin and free tryptophan and decrease gastric emptying and d-xylose absorption. In addition, in obesity an increase in interleukin (IL)-1 and IL-6 occurs in mesenteric fat tissue, which together with an increase in corticosterone, is associated with hyperglycemia, dyslipidemias and insulin resistance of obesity-related metabolic syndrome. These changes in circulating nutrients and hormones are sensed by hypothalamic neurons that influence food intake and metabolism. In anorectic tumor-bearing rats, we detected upregulation of IL-1beta and IL-1 receptor mRNA levels in the hypothalamus, a negative correlation between IL-1 concentration in cerebro-spinal fluid and food intake and high levels of hypothalamic serotonin, and these differences disappeared after tumor removal. Moreover, there is an interaction between serotonin and IL-1 in the development of cancer anorexia as well as an increase in hypothalamic dopamine and serotonin production. Immunohistochemical studies have shown a decrease in neuropeptide Y (NPY) and dopamine (DA) and an increase in serotonin concentration in tumor-bearing rats, in first- and second-order hypothalamic nuclei, while tumor resection reverted these changes and normalized food intake, suggesting negative regulation of NPY and DA systems by cytokines during anorexia, probably mediated by serotonin that appears to play a pivotal role in the regulation of food intake in cancer. Among the different forms of therapy, nutritional manipulation of diet in tumor-bearing state has been investigated. Supplementation of tumor bearing rats with omega-3 fatty acid vs. control diet delayed the appearance of tumor, reduced tumor-growth rate and volume, negated onset of anorexia, increased body weight, decreased cytokines production and increased expression of NPY and decreased alpha-melanocyte-stimulating hormone (alpha-MSH) in hypothalamic nuclei. These data suggest that omega-3 fatty acid suppressed pro-inflammatory cytokines production and improved food intake by normalizing hypothalamic food intake-related peptides and point to the possibility of a therapeutic use of these fatty acids. The sum of these data support the concept that immune cell-derived cytokines are closely related with the regulation of metabolism and have both central and peripheral actions, inducing anorexia via hypothalamic anorectic factors, including serotonin and dopamine, and inhibiting NPY leading to a reduction in food intake and body weight, emphasizing the interconnection of the immune and neuroendocrine systems in regulating metabolism during infectious process, cachexia and obesity.

Neurohumoral activation as a link to systemic manifestations of chronic lung disease

COPD is a major cause of death and disability worldwide. Treatment of COPD improves lung function but is unlikely to slow the steady downhill course of the disease or reduce mortality. In COPD, numerous abnormalities can be found outside the lung. These include systemic inflammation, cachexia, and skeletal muscle dysfunction. Thus, COPD has been called a systemic disease. Convincing data demonstrate that COPD causes neurohumoral activation. By precedents derived from chronic heart failure and other diseases characterized by neurohumoral activation, we propose that the negative consequences of neurohumoral activation, namely inflammation, cachexia, effects on ventilation, and skeletal muscle dysfunction, give rise to a self-perpetuating cycle that contributes to the pathogenesis of COPD, and which may involve respiratory muscle dysfunction as well as systemic inflammation. This concept may further help explain the increased cardiovascular morbidity and mortality in COPD patients. Currently, little is known about the effect of treatments directed at neurohumoral activation and COPD. As this aspect of COPD becomes better understood, new insights may direct novel therapeutic approaches.

Anti-inflammatory properties of cholinergic up-regulation: A new role for acetylcholinesterase inhibitors

We investigated the anti-inflammatory effects of acetylcholinesterase inhibitors (AChEI) at the cellular and molecular levels. AChEI suppressed lymphocyte proliferation and pro-inflammatory cytokine production, as well as extracellular esterase activity. Anti-inflammatory activity was mediated by the alpha7 nicotinic acetylcholine receptor (neuronal); the muscarinic receptor had the opposite effect. Treatment of the central nervous system (CNS) inflammatory disease, experimental autoimmune encephalomyelitis (EAE), with EN101, an anti-sense oligodeoxynucleotide, targeted to AChE mRNA, reduced the clinical severity of the disease and CNS inflammation intensity. The results of our experiments suggest that AChEI increase the concentration of extracellular acetylcholine (ACh), rendering it available for interaction with a nicotinic receptor expressed on lymphocytes. Our findings point to a novel role for AChEI which may be relevant in CNS inflammatory diseases such as EAE and multiple sclerosis. They also emphasize the importance of cholinergic balance in neurological disorders, such as Alzheimer's disease and myasthenia gravis, in which these drugs are used.

Central nervous system injury-induced immune deficiency syndrome

Infections are a leading cause of morbidity and mortality in patients with acute CNS injury. It has recently become clear that CNS injury significantly increases susceptibility to infection by brain-specific mechanisms: CNS injury induces a disturbance of the normally well balanced interplay between the immune system and the CNS. As a result, CNS injury leads to secondary immunodeficiency - CNS injury-induced immunodepression (CIDS) - and infection. CIDS might serve as a model for the study of the mechanisms and mediators of brain control over immunity. More importantly, understanding CIDS will allow us to work on developing effective therapeutic strategies, with which the outcome after CNS damage by a host of diseases could be improved by eliminating a major determinant of poor recovery.

Anesthesia-specific protection from endotoxic shock is not mediated through the vagus nerve

BACKGROUND

We have shown recently that volatile anesthetics significantly decrease inflammatory cytokine production and dramatically increase survival among rodents challenged with lipopolysaccharide (LPS). Because acetylcholine's interaction with nicotine receptors on tissue macrophages during vagus nerve stimulation has been implicated in the modulation of LPS-stimulated tumor necrosis factor alpha (TNF-alpha) production, we hypothesized that the mechanism of anesthetic immunoprotection is mediated through the vagus nerve.

METHODS

Male Sprague-Dawley rats underwent bilateral cervical vagotomy (n = 20) or sham operation (n = 6). Twenty-four hours postoperatively, vagotomized rats were randomized into 3 groups: LPS injection (V+LPS, n = 6), LPS injection followed by 60 minutes of isoflurane anesthesia (V+LPS+ISO, n = 7), or saline injection (V+S, n = 7). Sham animals were also given LPS (Sham+LPS). A sublethal dose of LPS (8 mg/kg) was used. Blood samples were collected via cardiac puncture 90 minutes after LPS or saline injection, and plasma was isolated for the measurement of cytokines by enzyme-linked immunosorbent assay. Statistical differences between groups were detected by 1-way analysis of variance.

RESULTS

Serum TNF-alpha was reduced significantly and interleukin (IL)-6 was abrogated completely among V+LPS+ISO rats, compared with both V+LPS and Sham+LPS animals (P < or = .05 for all). In contrast, levels of the anti-inflammatory cytokine IL-10 were similar among all LPS groups.

CONCLUSIONS

Isoflurane anesthesia administered simultaneously with the injection of LPS decreases serum production of TNF-alpha and IL-6 despite bilateral transection of the vagus nerve. Isoflurane-mediated attenuation of proinflammatory cytokine production occurs via a mechanism other than modulation of vagal output.

Without nerves, immunology remains incomplete -in vivo veritas

Interest in the interactions between nervous and immune systems involved in both pathological and homeostatic mechanisms of host defence has prompted studies of neuroendocrine immune modulation and cytokine involvement in neuropathologies. In this review we concentrate on a distinct area of homeostatic control of both normal and abnormal host defence activity involving the network of peripheral c-fibre nerve fibres. These nerve fibres have long been recognized by dermatologists and gastroenterologists as key players in abnormal inflammatory processes, such as dermatitis and eczema. However, the involvement of nerves can all too easily be regarded as that of isolated elements in a local phenomenon. On the contrary, it is becoming increasingly clear that neural monitoring of host defence activities takes place, and that involvement of central/spinal mechanisms are crucial in the co-ordination of the adaptive response to host challenge. We describe studies demonstrating neural control of host defence and use the specific examples of bone marrow haemopoiesis and contact sensitivity to highlight the role of direct nerve fibre connections in these activities. We propose a host monitoring system that requires interaction between specialized immune cells and nerve fibres distributed throughout the body and that gives rise to both neural and immune memories of prior challenge. While immunological mechanisms alone may be sufficient for local responsiveness to subsequent challenge, data are discussed that implicate the neural memory in co-ordination of host defence across the body, at distinct sites not served by the same nerve fibres, consistent with central nervous mediation.

Autonomic dysfunction predicts mortality in patients with multiple organ dysfunction syndrome of different age groups

OBJECTIVE

Multiple organ dysfunction syndrome (MODS) is the sequential failure of several organ systems after a trigger event, like sepsis or cardiogenic shock. Mortality rate is high, up to 70%. Autonomic dysfunction may substantially contribute to the development of MODS. Our study aimed to characterize a) the spectrum of autonomic dysfunction of critically ill MODS patients; b) whether autonomic dysfunction is different in patients receiving sedation, mechanical ventilation, or catecholamines; c) the age dependency of autonomic dysfunction in MODS; and d) whether autonomic dysfunction predicts mortality in MODS.

DESIGN

Prospective cohort study.

SETTING

Twelve-bed medical intensive care unit in a university center.

PATIENTS

Ninety consecutively admitted score-defined MODS patients.

INTERVENTIONS

Assessment of heart rate variability, baroreflex sensitivity, and chemoreflex sensitivity as markers of autonomic dysfunction. The patients were followed for 28-day mortality.

MEASUREMENTS AND MAIN RESULTS

Baroreflex sensitivity, chemoreflex sensitivity, and almost all indexes of heart rate variability were attenuated in comparison to normal range data. There was no association between the assessed heart rate variability variables, baroreflex sensitivity or chemoreflex sensitivity, and the presence of sedation or catecholamine therapy. Except for frequency-domain variables, pNN50 (percentage of differences of successive RR intervals differing >50 msecs) and rMSSD (root mean square of successive difference of N-N intervals), none of the measured variables were related to the presence of mechanical ventilation. Age dependency was detected for baroreflex sensitivity but not for heart rate variability indexes or chemoreflex sensitivity (across ages 24-96 yrs). lnVLF predicted 28-day mortality best in the entire cohort of patients and in a subgroup of patients with cardiogenic-triggered MODS.

CONCLUSIONS

Autonomic function of MODS patients is blunted, and this attenuation has prognostic implications. The extensive influence of MODS on autonomic function overwhelms and masks the well-known age dependency of autonomic function seen in healthy persons.

Tumor necrosis factor as a pharmacological target

As indicated by its name, tumor necrosis factor (TNF), cloned in 1985, was originally described as a macrophage-derived endogenous mediator that can induce hemorrhagic necrosis of solid tumors and kill some tumor cell lines in vitro. Unfortunately, its promising use as an anticancer agent was biased by its toxicity, which was clear soon from the first clinical trials with TNF in cancer. Almost at the same time TNF was being developed as an anticancer drug, it became clear that TNF was identical to a mediator responsible for cachexia associated with sepsis, which was termed cachectin. This research led to the finding that TNF is, in fact, the main lethal mediator of sepsis and to the publication of a huge number of articles showing that TNF inhibits the toxic effects of bacterial endotoxins, which are now described as systemic inflammatory response. Although the clinical trials with anti-TNF in sepsis have not been successful thus far, undoubtedly as a result of the complexity of this clinical setting, these studies ultimately led to the identification of TNF as a key inflammatory mediator and to the development of anti-TNF molecules (soluble receptors and antibodies) for important diseases including rheumatoid arthritis and Crohn's disease. On the other side, the mechanisms by which TNF and related molecules induce cell death have been studied in depth, and their knowledge might, in the future, suggest means of improve the therapeutic index of TNF in cancer.

Mechanisms of Disease: nicotine—a review of its actions in the context of gastrointestinal disease

Smoking tobacco is associated with a number of gastrointestinal disorders. In some, such as Crohn's disease and peptic ulcer disease, it increases the risk of disease and has a detrimental effect on their course. In others, such as ulcerative colitis, it decreases the risk of disease and can have a favorable effect on disease course and severity. In the eighteenth and nineteenth centuries, nicotine was used as a 'panacea' for various ailments, including abdominal symptoms--it is now under investigation to elucidate its role in gastrointestinal diseases that are associated with smoking. The actions of nicotine are complex; it is likely that its effects on the central nervous system, gastrointestinal tract and immune system interact with other risk factors, such as genetic susceptibility, to influence disease outcomes. This review focuses on the mechanisms of action of nicotine that might be relevant in gastrointestinal disease.

A randomized trial of nicotine enemas for active ulcerative colitis

BACKGROUND & AIMS

Ulcerative colitis (UC) is largely a disease of nonsmokers in which transdermal nicotine improves the symptoms but often causes adverse events (AEs). Nicotine enemas cause fewer AEs and were used as supplemental treatment for active UC.

METHODS

We treated 104 patients with active UC with either 6-mg nicotine enemas or placebo enemas for 6 weeks in a randomized double-blind study. Patients continued their oral therapy, if any, for UC: 68 patients were taking mesalamine, 15 patients were taking prednisolone, and 12 patients were taking thiopurines during the study. Clinical, sigmoidoscopic, and histologic assessments were made at baseline and at the end of the study and symptoms were recorded daily on a diary card. The primary end point was induction of clinical remission and clinical improvement also was measured by the UC disease activity index. After the study, patients then used nicotine enemas daily for 4 weeks and sigmoidoscopy with a biopsy examination was repeated. AEs and salivary cotinine levels were monitored throughout the study.

RESULTS

Clinical remission was achieved in 14 of 52 (27%) patients on active treatment and 14 of 43 (33%) patients on placebo (P = .55). The UC disease activity index improved by 1.45 points in the active group and by 1.65 points for those on placebo (P = .88). Only 1 patient discontinued treatment because of an AE (abdominal pain). In the 47 patients taking mesalamine only, active treatment conferred benefit that was not statistically significant; disease remission occurred in 9 of 25 patients on active therapy and 4 of 21 patients on placebo (P = .20).

CONCLUSIONS

Six-milligram nicotine enemas were well tolerated but were not found to be efficacious for active UC.

Activation of an efferent cholinergic pathway produces strong protection against myocardial ischemia/reperfusion injury in rats

OBJECTIVE

A vagus nerve-mediated, brain cholinergic protective mechanism activated by melanocortin peptides is operative in conditions of circulatory shock; moreover, there is anatomical evidence of dual vagal-cardiac efferent pathways in rats, which could play different roles in controlling heart function. Therefore, we investigated the role and functional mechanism of such vagal efferent pathway(s) in an experimental model of ischemic heart disease.

DESIGN

Randomized experimental study.

SETTING

Research laboratory.

SUBJECTS

Adult Wistar rats of either sex.

INTERVENTIONS

After bilateral cervical vagotomy (with or without pretreatment with atropine), efferent vagal fibers were electrically stimulated in rats subjected to coronary artery occlusion (5 mins) followed by reperfusion (5 mins). Other rats (intact, vagotomized, or pretreated with atropine) were treated with nanomolar doses of melanocortin peptides.

MEASUREMENTS AND MAIN RESULTS

Electrical stimulation of efferent vagal fibers (5 V, 2 m secs, 1-9 Hz, for the whole period of ischemia/reperfusion) strongly reduced the high incidence of severe arrhythmias and lethality, reduced the increase in free radical blood levels and left-ventricle histologic alterations, and augmented the extracellular signal-regulated kinase activation. Treatment with the melanocortin peptides adrenocorticotropin and gamma2-melanocyte-stimulating hormone (162 nmol/kg intravenously or 16.2 nmol/kg intracerebroventricularly, during coronary occlusion) produced the same protective effects of electrical stimulation and with the same muscarinic acetylcholine receptor-dependent mechanism, seemingly through brain activation (mediated by melanocortin MC3 receptors, as previously described) of such efferent vagal pathway.

CONCLUSIONS

The present results give evidence for the identification of a protective, melanocortin-activated, efferent vagal cholinergic pathway, operative in conditions of myocardial ischemia/reperfusion. These data suggest that melanocortins and pertinent compounds able to activate such a pathway could provide the potential for development of a new class of drugs for a novel approach to management of ischemic heart disease.

The cholinergic anti-inflammatory pathway

The regulation of the innate immune response is critical for controlling inflammation and for the prevention and treatment of diseases. We recently demonstrated that the efferent vagus nerve inhibits pro-inflammatory cytokine release and protects against systemic inflammation, and termed this vagal function "the cholinergic anti-inflammatory pathway." The discovery that the innate immune response is regulated partially through this neural pathway provides a new understanding of the mechanisms that control inflammation. In this review, we outline the cholinergic anti-inflammatory pathway and summarize the current insights into the mechanisms of cholinergic modulation of inflammation. We also discuss possible clinical implications of vagus nerve stimulation and cholinergic modalities in the treatment of inflammatory diseases.

Acute ileal inflammatory cytokine response induced by irradiation is modulated by subdiaphragmatic vagotomy

Neural involvement plays a role in the genesis of the peripheral inflammatory process that contributes to the irradiation intestinal disorders. However, little is known about the role of vagus nerve in modulating inflammatory process in rat. Here, we have shown that the NF-kappaB activation was consistent with the acute overexpression of pro-inflammatory cytokines (IL- 1beta, TNF-alpha, IL-6) at 3, 6, and 12 h induced by whole-body irradiation (8 Gy). Subdiaphragmatic vagotomy reduced NF-kappaB activation and cytokine transcription in the early period post-irradiation. In contrast, vagotomy amplified overexpression of irradiation-induced anti-cytokines (IL-10, IL-1Ra) and of receptors involved in anti-inflammatory effects (IL- 1RII, TNFRII). These results show that the vagus nerve is a pro-inflammatory pathway in early irradiation-induced intestinal inflammation.

Nutritional stimulation of cholecystokinin receptors inhibits inflammation via the vagus nerve

The immune system in vertebrates senses exogenous and endogenous danger signals by way of complex cellular and humoral processes, and responds with an inflammatory reaction to combat putative attacks. A strong protective immunity is imperative to prevent invasion of pathogens; however, equivalent responses to commensal flora and dietary components in the intestine have to be avoided. The autonomic nervous system plays an important role in sensing luminal contents in the gut by way of hard-wired connections and chemical messengers, such as cholecystokinin (CCK). Here, we report that ingestion of dietary fat stimulates CCK receptors, and leads to attenuation of the inflammatory response by way of the efferent vagus nerve and nicotinic receptors. Vagotomy and administration of antagonists for CCK and nicotinic receptors significantly blunted the inhibitory effect of high-fat enteral nutrition on hemorrhagic shock-induced tumor necrosis factor-alpha and interleukin-6 release (P < 0.05). Furthermore, the protective effect of high-fat enteral nutrition on inflammation-induced intestinal permeability was abrogated by vagotomy and administration of antagonists for CCK and nicotinic receptors. These data reveal a novel neuroimmunologic pathway, controlled by nutrition, that may help to explain the intestinal hyporesponsiveness to dietary antigens, and shed new light on the functionality of nutrition.

Human peripheral blood mononuclear cells express GABAA receptor subunits

The polymerase chain reaction was used to screen human peripheral blood mononuclear cells (PBMC) and Jurkat cells for the presence of GABAA receptor subunit mRNAs. Positive signals were detected for the alpha1, alpha3, beta2, beta3, delta and epsilon subunit mRNAs in both cell populations, with the Jurkat cells giving a positive signal for some additional species. Real-time PCR was used to confirm that PBMC, lymphocytes and monocytes contained significant levels of the alpha1 subunit mRNA and that PBMC and lymphocytes contained low levels of beta2 mRNA. The alpha1 subunit was detected in PBMC and fractionated T-cell populations, as well as Jurkat and HL-60 cell lines, by Western blotting and immunofluorescence using a specific antibody. The application of 1mM GABA reduced the specific increase in intracellular PBMC Ca2+ levels produced by addition of 1 nM fMLP: this effect was mimicked by muscimol, but not glycine, and was blocked by bicuculline. The inhibitory effect of GABA was limited to a subset of PBMC. We conclude that cells within the human PBMC population, including lymphocytes, express functional GABAA receptors and these receptors may modulate immune responses.

Acupuncture therapy for experimental stomach ulcer and c-Fos expression in rats

AIM: To determine the role of acupuncture therapy in treating experimental gastric ulcer in rats.

METHODS: Twenty-eight adult male Sprague-Dawley rats were randomly divided into four groups (pre-acupuncture group; acupuncture group; paradistance-acupuncture group; and control group), and pre-acupuncture, paradistance-acupuncture, and control groups received 5 μL acetic acid (200 mL/L HAc) injection after a same course of electroacupuncture (EA) treatment (4 Hz, 0.6 mA, 0.45 ms, 45 min for 4 d). The rats in these three groups recovered within 4 d. The acupuncture group received EA therapy for 4 d, after HAc injection. The stomach was dissected to compare the pathological structures of ulcer. Also c-Fos activation in the nuclei of solitary tract (NTS) was observed under microscope after regular immunohistochemistry staining of brain stem sections.

RESULTS: The number of ulcers was different among the four groups, especially between control group and paradistance-acupuncture group or pre-acupuncture group. In the latter group, the number of ulcers was much less. The gastric ulcer area was consistent with the histopathological results, indicating that pre-acupuncture had an obvious therapeutic effect on gastric ulcers. Acupuncture had a very modest effect and paradistance-acupuncture had no effect on gastric ulcers. No therapeutic effect was found in the control group. Fos-Li neurons in NTS induced by noxious gastric ulcer showed a significant difference between pre-acupuncture and control groups.

CONCLUSION: Acupuncture before ulceration can obviously alleviate ulcer. The production of c-Fos proves that the vagus nerve mediates the induction of c-Fos in nuclei of solitary tract following experimental ulceration, suggesting that parasympathetic afferents promote the process of noxious visceral stimulation.

Vagus nerve stimulation suppresses pain but has limited effects on neurogenic inflammation in humans

Left vagus nerve stimulation reduces pain perception in humans. In animal studies it has been shown that beyond the inhibitory effect, which the vagus nerve exerts via its widespread central connections, there might be also a peripheral effect on nociceptors. In humans, the exact mechanisms of VNS-mediated analgesia are still unclear. To test whether VNS also affects activation of primary nociceptive afferents in humans, we investigated 11 patients before and after implantation of a vagus nerve stimulator by using tonic pressure as pain stimulus. Vasodilator axon reflexes ("neurogenic" inflammation) were quantified by laser-Doppler-imaging and served as surrogates for primary afferent activation. Pain was measured on a visual analogue scale (VAS). The squeezing experiment was performed three times at 15 min intervals in each session. As controls 9 healthy age- and gender-matched subjects were studied. As shown in our previous study, VNS significantly reduces pain to tonic pressure. Likewise, there was a moderate reduction of the blood flow within the area of the axon reflex, which indicates a possible but limited inhibitory effect of VNS on peripheral nociceptors. Our data suggests that VNS might affect peripheral nociceptor function in humans. Since VNS has been shown to be more effective in experimental procedures in which pain magnitude is amplified by central processing, further studies are warranted to elucidate whether the central or peripheral effect is most important for VNS-mediated analgesia.

Regulation of CD8+ cytolytic T lymphocyte differentiation by a cholinergic pathway

In this report, we provide evidence that muscarinic receptors play a role in the generation of CD8+ cytolytic T lymphocytes. Analysis of mice with targeted deletions of each of the known muscarinic receptors (M1-M5) showed that CD8+ T cells from M1 receptor-deficient mice had a defect in the ability to differentiate into cytolytic T lymphocytes. Additional pharmacological experiments support the role of muscarinic receptors in wild type mice and suggest that acetylcholine may be involved. Together, these findings suggest that the M1 muscarinic receptor is involved in CTL development, thus providing novel insights into CD8+ T cell biology and the potential role of cholinergic signaling in immune regulation.

The vagus nerve and the nicotinic anti-inflammatory pathway

Physiological anti-inflammatory mechanisms are selected by evolution to effectively control the immune system and can be exploited for the treatment of inflammatory disorders. Recent studies indicate that the vagus nerve (which is the longest of the cranial nerves and innervates most of the peripheral organs) can modulate the immune response and control inflammation through a 'nicotinic anti-inflammatory pathway' dependent on the alpha7-nicotinic acetylcholine receptor (alpha7nAChR). Nicotine has been used in clinical trials for the treatment of ulcerative colitis, but its clinical applications are limited by its unspecific effects and subsequent toxicity. This article reviews recent advances supporting the therapeutic potential of selective nicotinic agonists in several diseases. Similar to the development of alpha- and beta-agonists for adrenoceptors, selective agonists for alpha7nAChR could represent a promising pharmacological strategy against infectious and inflammatory diseases.

Stimulation of the vagus nerve attenuates macrophage activation by activating the Jak2-STAT3 signaling pathway

Acetylcholine released by efferent vagus nerves inhibits macrophage activation. Here we show that the anti-inflammatory action of nicotinic receptor activation in peritoneal macrophages was associated with activation of the transcription factor STAT3. STAT3 was phosphorylated by the tyrosine kinase Jak2 that was recruited to the alpha7 subunit of the nicotinic acetylcholine receptor. The anti-inflammatory effect of nicotine required the ability of phosphorylated STAT3 to bind and transactivate its DNA response elements. In a mouse model of intestinal manipulation, stimulation of the vagus nerve ameliorated surgery-induced inflammation and postoperative ileus by activating STAT3 in intestinal macrophages. We conclude that the vagal anti-inflammatory pathway acts by alpha7 subunit-mediated Jak2-STAT3 activation.

Acupuncture and kidney disease

Acupuncture as a complex therapeutic system has been used to treat a variety of diseases and pathological conditions. Although the exact mechanism(s) of acupuncture remains unknown, some evidence suggests a mechanism initially involving signal transduction through connective tissue, with secondary involvement of other systems including the nervous system. Acupuncture has become increasingly popular in the Western countries as a therapy for pain and several chronic disorders difficult to manage with conventional treatments. Acupuncture and acupuncture-like somatic nerve stimulation have been used in different kidney diseases and several complications related to them. The effect of acupuncture techniques in some kidney diseases is reviewed on the basis of clinical reports as well as mechanisms that may possibly explain the beneficial effects mediated by acupressure/acupuncture. The potential effect of acupressure techniques in renal inflammation and whether these effects could be mediated through the newly identified cholinergic anti-inflammatory pathway are discussed.

Nicotinic receptors regulate B lymphocyte activation and immune response

The presence of nicotinic acetylcholine receptors (nicotinic receptors) composed of either alpha7 or alpha4 and beta2 subunits is revealed in B lymphocytes by means of radioligand binding assay and Cell ELISA. Mouse B lymphocytes contained 12,200+/-3200 of epibatidine-binding sites and 3130+/-750 of alpha-Bungarotoxin-binding sites per cell. Mice lacking nicotinic receptor subunits alpha4, beta2 or alpha7 had less serum IgG and IgG-producing cells in the spleen, but showed stronger immune response to both protein antigen in vivo and CD40-specific antibody in vitro than wild-type mice. Anti-CD40-stimulated proliferation of B lymphocytes from beta2 knockout, but not wild-type mice was inhibited with nicotine. Our results indicate that signalling through nicotinic receptors affects both the pre-immune state and activation of B lymphocytes in the immune response, possibly via CD40-dependent pathway. This could contribute to immune depression found in tobacco smokers.

The isolated perfused liver response to a 'second hit' of portal endotoxin during severe acute pancreatitis

BACKGROUND/AIM

During severe acute pancreatitis (AP), the liver may show an exaggerated response to the inflammatory products of gut injury transported in the portal vein. Our aim was to explore liver proinflammatory mediator production after a 'second hit' of portal lipopolysaccharide (LPS) during AP.

METHODS

Twenty-four rats underwent one of three 'first-hit' scenarios: (1) severe AP induced by intraductal glycodeoxycholic acid injection and intravenous caerulein infusion, (2) sham laparotomy, or (3) no first intervention. Eighteen hours later, all animals received a 'second hit' of portal LPS in an isolated liver perfusion system. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 concentrations were measured in portal and systemic serum, and in the perfusate 30 and 90 min after the 'second hit'. Neutrophil activation by the perfusate was assayed using dihydrorhodamine-123 fluorescence.

RESULTS

We observed a six-fold increase in IL-6 concentration across the liver during AP. All livers produced TNF-alpha after the portal LPS challenge, but this was not exaggerated by AP. No differential neutrophil activation by the perfusate was seen.

CONCLUSION

TNF-alpha, IL-1beta, IL-6 and neutrophil activator production by the isolated perfused liver, in response to a 'second hit' of portal LPS, does not appear to be enhanced during AP.