Pharmacological stimulation of the cholinergic antiinflammatory pathway

Self-Esteem and Autonomic Physiology: Parallels Between Self-Esteem and Cardiac Vagal Tone as Buffers of Threat

In this article a potential physiological connection to self-esteem is suggested: cardiac vagal tone, the degree of influence on the heart by the vagus, a primary nerve of the parasympathetic nervous system. This hypothesis emerges from parallels between the two literatures that suggest both self-esteem and cardiac vagal tone function to provide protection from threat responding. This article reviews these literatures and evidence and preliminary findings that suggest in some contexts self-esteem and cardiac vagal tone may exert an influence on each other. Last, the article discusses theoretical and applied health implications of this potential physiological connection to self-esteem.

Cholinergic modulation of inflammation

Recent studies have demonstrated that cytokine levels and inflammation can be regulated by specifically augmenting cholinergic signaling via the efferent vagus nerve and the alpha7 subunit-containing nicotinic acetylcholine receptor (alpha7nAChR). Cholinergic modalities, acting through vagus nerve- and/or alpha7nAChR-mediated mechanisms have been shown to suppress excessive inflammation in several experimental models of disease, including endotoxemic shock, sepsis, ischemia-reperfusion injury, hemorrhagic shock, colitis, postoperative ileus and pancreatitis. These studies have advanced the current understanding of the mechanisms regulating inflammation. They have also provided a rationale for exploring new possibilities to treat excessive, disease-underlying inflammation by applying selective cholinergic modalities in preclinical and clinical settings. An overview of this research is presented here.

The hepatic vagus nerve attenuates Fas-induced apoptosis in the mouse liver via alpha7 nicotinic acetylcholine receptor

BACKGROUND & AIMS

Although accumulating evidence has recently shown that the efferent vagus nerve attenuates systemic inflammation, it remains unclear whether or not the vagus nerve can affect Fas-induced liver apoptosis. We investigated the effect of the vagus nerve by using a selective hepatic vagotomy.

METHODS

We assessed the mortality and apoptosis in Fas-induced fulminant hepatitis in sham-operated and vagotomized male C57BL/6 mice. To determine how the nerve influences hepatocyte apoptosis, hepatitis was preceded by pretreatment with nicotine; PNU-282987, an alpha7 nicotinic acetylcholine receptor (AChR) agonist; liposome-encapsulated dichloromethylene diphosphonate (lipo-Cl(2)MDP), a macrophage eliminator; and Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP), an oxidative inhibitor.

RESULTS

Mortality in the vagotomized mice was significantly higher than that in the sham-operated mice following intravenous administration with the anti-Fas antibody Jo-2. This result was also supported by the data from both terminal deoxynucleotidyl-transferase mediated dUTP nick-end labeling and caspase-3 assay, in which vagotomized livers showed a significant elevation in the number of apoptotic hepatocytes and increased caspase-3 activity following Jo-2 treatment compared with the sham-operated livers. Supplementation with nicotine and PNU-282987 dose dependently inhibited this detrimental effect of the vagotomy. Moreover, the vagotomy-triggered exacerbation of Fas-induced hepatitis was completely blocked by lipo-Cl(2)MDP. Similarly, pretreatment with MnTBAP also completely suppressed the vagotomy-triggered exacerbation.

CONCLUSIONS

The hepatic vagus nerve appears to play an important role in attenuating Fas-induced hepatocyte apoptosis through alpha7 nicotinic AChR, perhaps by causing the Kupffer cells to reduce their generation of an excessive amount of reactive oxygen species.

Cholinergic agonists attenuate renal ischemia-reperfusion injury in rats

Inflammation plays a significant role in the pathophysiology of renal ischemia-reperfusion injury. Local inflammation is modulated by the brain via the vagus nerve and nicotinic acetylcholine receptors such that electrical or pharmacologic stimulation of this cholinergic anti-inflammatory pathway results in suppression of proinflammatory cytokine production. We examined the effects of cholinergic stimulation using agonists, nicotine or GTS-21, given before or after bilateral renal ischemia-reperfusion injury in rats. Pretreatment of rats with either agonist significantly attenuated renal dysfunction and tubular necrosis induced by renal ischemia. Similarly, tumor necrosis factor-alpha protein expression and leukocyte infiltration of the kidney were markedly reduced following treatment with cholinergic agonists. We found functional nicotinic acetylcholine receptors were present on rat proximal tubule epithelial cells. Cholinergic stimulation significantly decreased tubular necrosis in vagotomized rats after injury, implying an intact vagus nerve is not required for this renoprotective effect.

Pharmacologic cholinesterase inhibition improves survival in experimental sepsis

OBJECTIVE

Lethal sepsis occurs when an excessive inflammatory response evolves that cannot be controlled by physiologic anti-inflammatory mechanisms, such as the recently described cholinergic anti-inflammatory pathway. Here we studied whether the cholinergic anti-inflammatory pathway can be activated by pharmacologic cholinesterase inhibition in vivo.

DESIGN

Prospective, randomized laboratory investigation that used an established murine sepsis model.

SETTING

Research laboratory in a university hospital.

SUBJECTS

Female C57BL/6 mice.

INTERVENTIONS

Sepsis in mice was induced by cecal ligation and puncture. Animals were treated immediately with intraperitoneal injections of nicotine (400 microg/kg), physostigmine (80 microg/kg), neostigmine (80 microg/kg), or solvent three times daily for 3 days.

MEASUREMENTS AND MAIN RESULTS

Treatment with physostigmine significantly reduced lethality (p < or = .01) as efficiently as direct stimulation of the cholinergic anti-inflammatory pathway with nicotine (p < or = .05). Administration of cholinesterase inhibitors significantly down-regulated the binding activity of nuclear factor-kappaB (p < or = .05) and significantly reduced the concentration of circulating proinflammatory cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 (p < or = .001), and pulmonary neutrophil invasion (p < or = .05). Animals treated with the peripheral cholinesterase inhibitor neostigmine showed no difference compared with physostigmine-treated animals.

CONCLUSIONS

Our results demonstrate that cholinesterase inhibitors can be used successfully in the treatment of sepsis in a murine model and may be of interest for clinical use.

Transcutaneous vagus nerve stimulation reduces serum high mobility group box 1 levels and improves survival in murine sepsis

OBJECTIVE

Electrical vagus nerve stimulation inhibits proinflammatory cytokine production and prevents shock during lethal systemic inflammation through an alpha7 nicotinic acetylcholine receptor (alpha7nAChR)-dependent pathway to the spleen, termed the cholinergic anti-inflammatory pathway. Pharmacologic alpha7nAChR agonists inhibit production of the critical proinflammatory mediator high mobility group box 1 (HMGB1) and rescue mice from lethal polymicrobial sepsis. Here we developed a method of transcutaneous mechanical vagus nerve stimulation and then investigated whether this therapy can protect mice against sepsis lethality.

DESIGN

Prospective, randomized study.

SETTING

Institute-based research laboratory.

SUBJECTS

Male BALB/c mice.

INTERVENTIONS

Mice received lipopolysaccharide to induce lethal endotoxemia or underwent cecal ligation and puncture to induce polymicrobial sepsis. Mice were then randomized to receive electrical, transcutaneous, or sham vagus nerve stimulation and were followed for survival or euthanized at predetermined time points for cytokine analysis.

MEASUREMENTS AND MAIN RESULTS

Transcutaneous vagus nerve stimulation dose-dependently reduced systemic tumor necrosis factor levels during lethal endotoxemia. Treatment with transcutaneous vagus nerve stimulation inhibited HMGB1 levels and improved survival in mice with polymicrobial sepsis, even when administered 24 hrs after the onset of disease.

CONCLUSIONS

Transcutaneous vagus nerve stimulation is an efficacious treatment for mice with lethal endotoxemia or polymicrobial sepsis.

Stimulated production of proinflammatory cytokines covaries inversely with heart rate variability

OBJECTIVE

To examine whether high-frequency heart rate variability, an indirect measure of parasympathetic (vagal) control over variations in heart rate, is associated with immune reactivity to an in vitro inflammatory challenge. Convergent evidence from the animal literature shows that the autonomic nervous system plays a key role in regulating the magnitude of immune responses to inflammatory stimuli. Signaling by the parasympathetic system inhibits the production of proinflammatory cytokines by activated monocytes/macrophages and thus decreases local and systemic inflammation. As yet, no direct human evidence links parasympathetic activity to inflammatory competence.

METHODS

We examined the relationship of variations in heart rate, recorded during paced respiration, to lipopolysaccharide-induced production of the inflammatory cytokines interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and IL-10 among a community sample of 183 healthy adults (mean age = 45 years; 59% male; 92% White, 7% African-American).

RESULTS

Consistent with animal findings, higher derived estimates of vagal activity measured during paced respiration were associated with lower production of the proinflammatory cytokines TNF-alpha and IL-6 (r = -.18 to -.30), but were not related to production of the anti-inflammatory cytokine IL-10. These associations persisted after controlling for demographic and health characteristics, including age, gender, race, years of education, smoking, hypertension, and white blood cell count.

CONCLUSIONS

These data provide initial human evidence that vagal activity is inversely related to inflammatory competence, raising the possibility that vagal regulation of immune reactivity may represent a pathway linking psychosocial factors to risk for inflammatory disease.

Activation of the cholinergic anti-inflammatory pathway ameliorates postoperative ileus in mice

BACKGROUND & AIMS

We previously showed that intestinal inflammation is reduced by electrical stimulation of the efferent vagus nerve, which prevents postoperative ileus in mice. We propose that this cholinergic anti-inflammatory pathway is mediated via alpha7 nicotinic acetylcholine receptors expressed on macrophages. The aim of this study was to evaluate pharmacologic activation of the cholinergic anti-inflammatory pathway in a mouse model for postoperative ileus using the alpha7 nicotinic acetylcholine receptor-agonist AR-R17779.

METHODS

Mice were pretreated with vehicle, nicotine, or AR-R17779 20 minutes before a laparotomy (L) or intestinal manipulation (IM). Twenty-four hours thereafter gastric emptying was determined using scintigraphy and intestinal muscle inflammation was quantified. Nuclear factor-kappaB transcriptional activity and cytokine production was assayed in peritoneal macrophages.

RESULTS

Twenty-four hours after surgery IM led to a delayed gastric emptying compared with L (gastric retention: L(saline) 14% +/- 4% vs IM(saline) 38% +/- 10%, P = .04). Pretreatment with AR-R17779 prevented delayed gastric emptying (IM(AR-R17779) 15% +/- 4%, P = .03). IM elicited inflammatory cell recruitment (L(saline) 50 +/- 8 vs IM(saline) 434 +/- 71 cells/mm(2), P = .001) which was reduced by AR-R17779 pretreatment (IM(AR-R17779) 231 +/- 32 cells/mm(2), P = .04). An equimolar dose of nicotine was not tolerated. Subdiaphragmal vagotomy did not affect the anti-inflammatory properties of AR-R17779. In peritoneal macrophages, both nicotinic agonists reduced nuclear factor kappaB transcriptional activity and proinflammatory cytokine production, with nicotine being more effective than AR-R17779.

CONCLUSIONS

AR-R17779 treatment potently prevents postoperative ileus, whereas toxicity limits nicotine administration to ineffective doses. Our data further imply that nicotinic inhibition of macrophage activation may involve other receptors in addition to alpha7 nicotinic acetylcholine receptor.

Cholinergic anti-inflammatory pathway activity and High Mobility Group Box-1 (HMGB1) serum levels in patients with rheumatoid arthritis

High Mobility Group Box-1 (HMGB1) is a cytokine implicated in the pathogenesis of rheumatoid arthritis (RA) and other inflammatory diseases. The cholinergic anti-inflammatory pathway, a vagus nerve-dependent mechanism, inhibits HMGB1 release in experimental disease models. Here, we examine the relationship between vagus nerve activity and HMGB1 in patients with RA. We compared RR interval variability, an index of cardiac vagal modulation, HMGB1 and hsCRP serum levels, and disease activity scores in thirteen RA patients and eleven age- and sex-matched controls. In RA patients, serum levels of HMGB1 and hsCRP were elevated as compared with controls (HMGB1=71 ng/mL [45-99] vs. 18 ng/mL [0-40], P<0.0001; hsCRP=14.5 mg/L [0.7-59] vs. 1 mg/L [0.4-2.9], P<0.001). RR interval variability in RA patients was significantly decreased as compared with controls (HF=38 msec2 [14-80] vs. 288 msec2 [38-364], P<0.0001; rMSSD=20.9+/-9.79 msec, 52.6+/-35.3 msec, P<0.01). HMGB1 levels and RR interval variability were significantly related (rho=-0.49, P<0.01). HMGB1 serum levels significantly correlated with disease activity scores (DAS-28) in patients with RA (P=0.004). The study design does not enable a determination of causality, but the results are consistent with the hypothesis that decreased cholinergic anti-inflammatory pathway activity is associated with increased HMGB1 levels in patients with RA.

Cholinergic anti-inflammatory pathway activity and High Mobility Group Box-1 (HMGB1) serum levels in patients with rheumatoid arthritis

High Mobility Group Box-1 (HMGB1) is a cytokine implicated in the pathogenesis of rheumatoid arthritis (RA) and other inflammatory diseases. The cholinergic anti-inflammatory pathway, a vagus nerve-dependent mechanism, inhibits HMGB1 release in experimental disease models. Here, we examine the relationship between vagus nerve activity and HMGB1 in patients with RA. We compared RR interval variability, an index of cardiac vagal modulation, HMGB1 and hsCRP serum levels, and disease activity scores in thirteen RA patients and eleven age- and sex-matched controls. In RA patients, serum levels of HMGB1 and hsCRP were elevated as compared with controls (HMGB1=71 ng/mL [45-99] vs. 18 ng/mL [0-40], P<0.0001; hsCRP=14.5 mg/L [0.7-59] vs. 1 mg/L [0.4-2.9], P<0.001). RR interval variability in RA patients was significantly decreased as compared with controls (HF=38 msec2 [14-80] vs. 288 msec2 [38-364], P<0.0001; rMSSD=20.9+/-9.79 msec, 52.6+/-35.3 msec, P<0.01). HMGB1 levels and RR interval variability were significantly related (rho=-0.49, P<0.01). HMGB1 serum levels significantly correlated with disease activity scores (DAS-28) in patients with RA (P=0.004). The study design does not enable a determination of causality, but the results are consistent with the hypothesis that decreased cholinergic anti-inflammatory pathway activity is associated with increased HMGB1 levels in patients with RA.

C-reactive protein and vulnerability to mental stress-induced myocardial ischemia

Myocardial ischemia provoked in the laboratory during mental stress (MSI) in patients with stable coronary artery disease (CAD) predicts subsequent clinical events. The pathophysiology of MSI differs from that of exercise ischemia, and the mechanisms tying MSI to poor prognosis are not known. C-reactive protein (CRP) is a risk marker for cardiovascular events in patients with CAD, but little is known regarding the relationship of CRP to MSI. The purpose of this study was to examine the association of CRP to risk of MSI in CAD patients. Eighty-three patients with stable CAD underwent simultaneous single-photon emission computed tomography (SPECT) imaging with technetium-99m tetrofosmin myocardial perfusion imaging (MPI) and transthoracic echocardiography (TTE), at rest and during MS induced by laboratory mental stress. Serum CRP levels were measured 24 h after MS. MSI was defined by the presence of a new perfusion defect on SPECT and/or new regional wall motion abnormality on TTE during MS. Of the 83 patients, 30 (36%) developed MSI. There was no difference in gender, sex, BMI, histories of diabetes, hypertension, smoking, lipid profile, medications used (including statins, beta-blockers, ACE inhibitors, and aspirin), or hemodynamic response during MS between those with and without MSI. In univariate logistic regression analysis, each unit (1 mg/L) increase in CRP level was associated with 20% higher risk of MSI (OR 1.2, 95% CI 1.01-1.39, P=.04). This relationship remained in multivariate models. These data suggest that levels of CRP may be a risk marker for MSI in patients with CAD.

Stimulation of alpha 7 cholinergic receptors inhibits lipopolysaccharide-induced neutrophil recruitment by a tumor necrosis factor alpha-independent mechanism

The cholinergic nervous system controls inflammation by inhibiting the release of proinflammatory cytokines such as tumor necrosis factor (TNF) alpha from lipopolysaccharide (LPS)-stimulated macrophages. The key endogenous mediator of this so-called cholinergic anti-inflammatory pathway is acetylcholine, the principal neurotransmitter of the vagus nerve, which specifically interacts with alpha7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. We here investigated the capacity of the selective alpha7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21) to inhibit LPS-induced inflammatory responses in mice in vivo. To this end, mice received an intraperitoneal injection of LPS (from Escherichia coli, 200 microg) preceded by GTS-21 (4 mg/kg) or vehicle. GTS-21 strongly inhibited LPS-induced TNF-alpha release into the peritoneal cavity and the circulation. In addition, GTS-21 attenuated the influx of neutrophils into peritoneal fluid upon administration of LPS. This inhibitory effect on neutrophil recruitment by GTS-21 was independent of its effect on TNF-alpha release, considering that etanercept, a potent TNF-alpha-blocking protein containing the extracellular domain of the p75 TNF-alpha receptor, did not influence LPS-induced neutrophil influx either in the presence or in the absence of GTS-21 treatment. GTS-21 did not reduce the local secretion of macrophage inflammatory protein 2 and keratinocyte-derived cytokine, suggesting that altered concentrations of these neutrophil-attracting chemokines did not contribute to GTS-21-induced inhibition of neutrophil migration. These data identify a novel anti-inflammatory effect of chemical alpha7 cholinergic receptor stimulation that is independent from its capacity to inhibit TNF-alpha production.

A novel inhibitor of inflammatory cytokine production (CNI-1493) reduces rodent post-hemorrhagic vasospasm

INTRODUCTION

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a devastating complication, yet despite multiple lines of investigation an effective treatment remains lacking. Cytokine-mediated inflammation has been implicated as a causative factor in the development of posthemorrhagic vasospasm. In previous experiments using the rat femoral artery model of vasospasm, we demonstrated that elevated levels of the proinflammatory cytokine interleukin (IL)-6 are present after hemorrhage and that a polyclonal antibody against IL-6 is capable of attenuating experimental vasospasm.

METHODS

In the present study, we tested the ability of a novel selective proinflammatory cytokine inhibitor (CNI-1493) to protect against the occurrence of experimental vasospasm in the same rat femoral artery model. CNI-1493 was administered by injection directly into the blood-filled femoral pouches of animals at the time of their initial surgery (hemorrhage). Control animals received an equal volume of vehicle alone. Animals were killed at 8 days posthemorrhage and degree of vasospasm was assessed by image analysis of artery cross-sectional area. In a separate series of experiments, enzyme-linked immunosorbent assay (ELISA) was used to assess levels of the proinflammatory cytokine IL-6 and the prototypical antiinflammatory cytokine transforming growth factor (TGF)-beta1 after treatment with CNI-1493.

RESULTS

Pretreatment with CNI-1493 provided dose-dependent attenuation of posthemorrhagic vasospasm, with the highest dose (200 microg in 8 microL dH2O) causing complete reversal of vasospasm (vessel cross-sectional area ratio 1.06 +/- 0.04 versus 0.87 +/- 0.06, p < 0.05, one-way analysis of variance). Assessment of cytokine levels by ELISA confirmed the selectivity of CNI-1493 by demonstrating significant reductions in IL-6 levels, but no suppression of TGF-beta1 levels.

CONCLUSIONS

These findings support the conclusion that inflammatory cytokines, in particular IL-6, play an important role in development of vasospasm in the rat femoral artery model. Furthermore, these results suggest that the inhibition of inflammatory cytokines may be an appropriate strategy for the treatment of vasospasm after SAH.

Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve

OBJECTIVE

To test the hypothesis that administration of ghrelin attenuates inflammatory responses in sepsis through vagal nerve stimulation.

SUMMARY BACKGROUND DATA

Ghrelin has been demonstrated to possess multiple functions, including stimulation of the vagus nerve. Our recent study has shown that plasma levels of ghrelin were significantly reduced in sepsis; and ghrelin administration improved organ perfusion and function. However, it remained unknown whether ghrelin also decreases proinflammatory cytokines in sepsis and, if so, whether the down-regulatory effect of ghrelin is mediated by activation of the vagus nerve.

METHODS

Male rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 hours after CLP, a bolus intravenous injection of 2 nmol ghrelin was followed by a continuous infusion of 12 nmol ghrelin via a primed 200-microL Alzet mini-pump for 15 hours. At 20 hours after CLP, plasma and peritoneal fluid levels of TNF-alpha and IL-6 were determined. The direct effect of ghrelin on cytokine production was studied using cultured normal rat Kupffer cells or peritoneal macrophages stimulated by lipopolysaccharide (LPS). In additional animals, vagotomy or sham vagotomy was performed in sham and septic animals immediately prior to ghrelin administration and cytokine levels were then measured.

RESULTS

Ghrelin significantly reduced TNF-alpha and IL-6 levels in sepsis. In contrast, ghrelin did not inhibit TNF-alpha and IL-6 release from LPS-stimulated Kupffer cells or peritoneal macrophages. However, vagotomy, but not sham vagotomy, prevented ghrelin's down-regulatory effect on TNF-alpha and IL-6 production.

CONCLUSIONS

Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve. Pharmacologic stimulation of the vagus nerve may offer a novel approach of anti-sepsis therapy.

The alpha7 nicotinic acetylcholine receptor as a pharmacological target for inflammation

The physiological regulation of the immune system encompasses comprehensive anti-inflammatory mechanisms that can be harnessed for the treatment of infectious and inflammatory disorders. Recent studies indicate that the vagal nerve, involved in control of heart rate, hormone secretion and gastrointestinal motility, is also an immunomodulator. In experimental models of inflammatory diseases, vagal nerve stimulation attenuates the production of proinflammatory cytokines and inhibits the inflammatory process. Acetylcholine, the principal neurotransmitter of the vagal nerve, controls immune cell functions via the alpha7 nicotinic acetylcholine receptor (alpha7nAChR). From a pharmacological perspective, nicotinic agonists are more efficient than acetylcholine at inhibiting the inflammatory signaling and the production of proinflammatory cytokines. This 'nicotinic anti-inflammatory pathway' may have clinical implications as treatment with nicotinic agonists can modulate the production of proinflammatory cytokines from immune cells. Nicotine has been tested in clinical trials as a treatment for inflammatory diseases such as ulcerative colitis, but the therapeutic potential of this mechanism is limited by the collateral toxicity of nicotine. Here, we review the recent advances that support the design of more specific receptor-selective nicotinic agonists that have anti-inflammatory effects while eluding its collateral toxicity.

Is metabolic syndrome X a disorder of the brain with the initiation of low-grade systemic inflammatory events during the perinatal period?

An imbalance between pro- and anti-inflammatory molecules occurs in metabolic syndrome X. High-energy diet, saturated fats and trans-fats during perinatal period could suppress Delta(6) and Delta(5) desaturases both in the maternal and fetal tissues, resulting in a decrease in the concentrations of long-chain polyunsaturated fatty acids (LCPUFAs): arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that have a negative feedback control on inflammation. EPA, DHA and AA augment endothelial nitric oxide synthesis, potentiate insulin action both in the peripheral tissues and brain and alter leptin production. LCPUFAs are essential for brain growth and development and synaptogenesis and modulate the action of several neurotransmitters and hypothalamic peptides. This suggests that metabolic syndrome X could be a disorder of the brain due to suboptimal LCPUFAs during perinatal period that triggers low-grade systemic inflammation, implying that perinatal strategies are needed to prevent its development.

Activation of the alpha7 nAChR reduces acid-induced acute lung injury in mice and rats

New evidence indicates that neural mechanisms can down-regulate acute inflammation. In these studies, we tested the potential role of the alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) in a rodent model of acid-induced acute lung injury. We first determined that the alpha7 nAChR was expressed by alveolar macrophages and lung epithelial cells. Then, using an acid-induced acute lung injury mouse model, we found that nicotine, choline, and PNU-282,987 (a specific alpha7 nAChR agonist) decreased excess lung water and lung vascular permeability, and reduced protein concentration in the bronchoalveolar lavage (BAL). Deficiency of alpha7 nAChR resulted in a 2-fold increase in excess lung water and lung vascular permeability. The reduction of proinflammatory cytokines (macrophage inflammatory protein-2 and TNF-alpha) in the BAL with nicotine probably resulted from the suppression of NF-kappaB activation in alveolar macrophages. The beneficial effect of nicotine was also tested in rat model of acid-induced acute lung injury in which BAL protein and receptor for advanced glycation end products (RAGE), a marker of type I cell injury, were reduced by nicotine treatment. These results indicate that activation of alpha7 nAChR may provide a new therapeutic pathway for the treatment of acute lung injury.

The role of the intestinal barrier in the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in neonates and is increasing in frequency because of recent advances in neonatal care. NEC develops in a stressed preterm infant in the setting of intestinal barrier disruption, systemic inflammation, and leads to, multisystem organ failure. The intestinal barrier lies at the interface between microbes within the intestinal lumen and the immune system of the host, and has both immunological and mechanical components. These components serve to protect the host from invading pathogens and, at the same time, provide a surface area for nutrient absorption. Factors that lead to impairments in the function of the intestinal barrier may predispose the host to the invasion of gut-derived microbes and to the development of systemic inflammatory disease. This process, termed "bacterial translocation," may be compounded during instances in which the mechanisms that regulate the repair of the intestinal barrier are disrupted. Bacterial translocation is of particular concern to the newborn patient, in which immaturity of the mechanical barrier and incomplete development of the host immune system combine to render the host at particular risk for the development of intestinal inflammation. This review will serve to provide an overview of recent evidence regarding the components of the intestinal barrier, and the mechanisms by which disruptions in barrier function may contribute to the pathogenesis of NEC.

Adaptive changes in acetylcholinesterase gene expression as mediators of recovery from chemical and biological insults

Both organophosphate (OP) exposure and bacterial infection notably induce short- and long-term cholinergic responses. These span the central and peripheral nervous system, neuromuscular pathway and hematopoietic cells and involve over-expression of the "readthrough" variant of acetylcholinesterase, AChE-R, and its naturally cleavable C-terminal peptide ARP. However, the causal involvement of these changes with post-exposure recovery as opposed to apoptotic events remained to be demonstrated. Here, we report the establishment of stably transfected cell lines expressing catalytically active human "synaptic" AChE-S or AChE-R which are fully viable and non-apoptotic. In addition, intraperitoneally injected synthetic mouse ARP (mARP) elevated serum AChE levels post-paraoxon exposure. Moreover, mARP treatment ameliorated post-exposure increases in corticosterone and decreases in AChE gene expression and facilitated earlier retrieval of motor activity following both paraoxon and lipopolysaccharide (LPS) exposures. Our findings suggest a potential physiological role for overproduction of AChE-R and the ARP peptide following exposure to both chemical warfare agents and bacterial LPS.

Review article: bacterial translocation in the critically ill--evidence and methods of prevention

BACKGROUND

Delayed sepsis, systemic inflammatory response syndrome (SIRS) and multiorgan failure remain major causes of morbidity and mortality on intensive care units. One factor thought to be important in the aetiology of SIRS is failure of the intestinal barrier resulting in bacterial translocation and subsequent sepsis.

AIM

This review summarizes the current knowledge about bacterial translocation and methods to prevent it.

METHODS

Relevant studies during 1966-2006 were identified from a literature search. Factors, which detrimentally affect intestinal barrier function, are discussed, as are methods that may attenuate bacterial translocation in the critically ill patient.

RESULTS

Methodological problems in confirming bacterial translocation have restricted investigations to patients undergoing laparotomy. There are only limited data available relating to specific interventions that might preserve intestinal barrier function or limit bacterial translocation in the intensive care setting. These can be categorized broadly into pre-epithelial, epithelial and post-epithelial interventions.

CONCLUSIONS

A better understanding of factors that influence translocation could result in the implementation of interventions which contribute to improved patient outcomes. Glutamine supplementation, targeted nutritional intervention, maintaining splanchnic flow, the judicious use of antibiotics and directed selective gut decontamination regimens hold some promise of limiting bacterial translocation. Further research is required.

Nicotine exposure alters in vivo human responses to endotoxin

The alpha 7 nicotinic receptor is reportedly a key element in the cholinergic anti-inflammatory pathway. Because a prototypical ligand for this receptor is nicotine, we studied the in vivo human response to bacterial endotoxin or lipopolysaccharide (LPS) in the context of nicotine or placebo pretreatment. Twelve adult male normal subjects were studied prospectively. Six received overnight transcutaneous nicotine administration by application of a standard patch (7 mg). Six hours later, all subjects were given an intravenous dose of endotoxin (2 ng/kg) and were evaluated for an additional 24 h for circulating levels of inflammatory biomarkers, vital signs and symptoms. The nicotine subjects had elevated blood levels of the nicotine metabolite, continine, prior to and throughout the 24-h post-endotoxin exposure phase. Subjects receiving nicotine exhibited a significantly lower temperature response as well as attenuated cardiovascular responses for 2.5-6 h after LPS exposure. In addition, increased circulating interkeukin (IL)-10 and cortisol levels were also noted in nicotine subjects. These data indicate an alteration in LPS-induced systemic inflammatory responses in normal subjects exposed to transcutaneous nicotine. In this model of abbreviated inflammation, nicotine exposure attenuates the febrile response to LPS and promotes a more prominent anti-inflammatory phenotype.

C-reactive protein and vulnerability to mental stress-induced myocardial ischemia

Myocardial ischemia provoked in the laboratory during mental stress (MSI) in patients with stable coronary artery disease (CAD) predicts subsequent clinical events. The pathophysiology of MSI differs from that of exercise ischemia, and the mechanisms tying MSI to poor prognosis are not known. C-reactive protein (CRP) is a risk marker for cardiovascular events in patients with CAD, but little is known regarding the relationship of CRP to MSI. The purpose of this study was to examine the association of CRP to risk of MSI in CAD patients. Eighty-three patients with stable CAD underwent simultaneous single-photon emission computed tomography (SPECT) imaging with technetium-99m tetrofosmin myocardial perfusion imaging (MPI) and transthoracic echocardiography (TTE), at rest and during MS induced by laboratory mental stress. Serum CRP levels were measured 24 h after MS. MSI was defined by the presence of a new perfusion defect on SPECT and/or new regional wall motion abnormality on TTE during MS. Of the 83 patients, 30 (36%) developed MSI. There was no difference in gender, sex, BMI, histories of diabetes, hypertension, smoking, lipid profile, medications used (including statins, beta-blockers, ACE inhibitors, and aspirin), or hemodynamic response during MS between those with and without MSI. In univariate logistic regression analysis, each unit (1 mg/L) increase in CRP level was associated with 20% higher risk of MSI (OR 1.2, 95% CI 1.01-1.39, P=.04). This relationship remained in multivariate models. These data suggest that levels of CRP may be a risk marker for MSI in patients with CAD.

Infection After Acute Ischemic Stroke

Background and Purpose— Infection after experimental focal ischemia may result from brain-induced immunodepression, but it is unsettled whether a similar syndrome occurs in human stroke.

Summary of Review— Many patients develop infections shortly after acute stroke regardless of optimal management. Mortality is higher in these patients and the severity of stroke is the strongest determinant of the infectious risk. However, it is controversial whether infections promote neurological worsening or alternatively represent a marker of severe disease. The brain and the immune system are functionally linked through neural and humoral pathways, and decreased immune competence with higher incidence of infections has been demonstrated in several acute neurological conditions. In experimental brain ischemia, infections are associated with the activation of the autonomous nervous system and neuroendocrine pathways, which increase the strength of anti-inflammatory signals. A strong cytokine-mediated anti-inflammatory response was recently observed in stroke patients at higher risk of infection, although infection could not demonstrate an independent association with the progression of the symptoms.

Conclusions— The appearance of infection in patients with acute stroke obeys in part to immunological mechanisms triggered by acute brain injury. An excessive anti-inflammatory response is a key facilitating factor for the development of infection, and it is likely that this immunological response represents an adaptive mechanism to brain ischemia. Contrarily, it is unclear whether infection contributes independently to poor outcome in human stroke. Overall, a better understanding of the cross-talk between the brain and the immune system might lead to more effective therapies in patients with acute stroke.

Controlling inflammation: the cholinergic anti-inflammatory pathway

Innate immune responses and inflammation are regulated in part by neural mechanisms. In the present paper, we summarize experimental evidence that reveals that innate immunity and inflammation are controlled by the vagus nerve, previously known as a regulator of other vital physiological functions. Activation of vagus nerve cholinergic signalling inhibits TNF (tumour necrosis factor) and other pro-inflammatory cytokine overproduction through 'immune' alpha7 nicotinic receptor-mediated mechanisms. This efferent vagus nerve-based 'cholinergic anti-inflammatory pathway' has been elucidated as a critical regulator of inflammation in several experimental models of diseases. Our recent observations have shown that activation of central (brain) cholinergic transmission by selective muscarinic receptor ligands results in lower systemic TNF levels in rodents and indicate that the efferent vagus nerve may provide a functional brain-to-immune connection. Thus central cholinergic signalling is implicated in the activation of the cholinergic anti-inflammatory pathway. Electrical vagus nerve stimulation is clinically approved for the treatment of epilepsy and depression and current knowledge suggests that it could be utilized to control inflammation. Advances in understanding the receptor and molecular mechanisms of cholinergic anti-inflammatory signalling indicate that selective alpha7 nicotinic receptor agonists and centrally acting cholinergic enhancers can be used in the treatment of pathological conditions characterized by cytokine overproduction.

Physiology and immunology of the cholinergic antiinflammatory pathway

Cytokine production by the immune system contributes importantly to both health and disease. The nervous system, via an inflammatory reflex of the vagus nerve, can inhibit cytokine release and thereby prevent tissue injury and death. The efferent neural signaling pathway is termed the cholinergic antiinflammatory pathway. Cholinergic agonists inhibit cytokine synthesis and protect against cytokine-mediated diseases. Stimulation of the vagus nerve prevents the damaging effects of cytokine release in experimental sepsis, endotoxemia, ischemia/reperfusion injury, hemorrhagic shock, arthritis, and other inflammatory syndromes. Herein is a review of this physiological, functional anatomical mechanism for neurological regulation of cytokine-dependent disease that begins to define an immunological homunculus.

Heart rate and microinflammation in men: a relevant atherothrombotic link

OBJECTIVE AND BACKGROUND

To explore the possibility that increased resting heart rate (HR) is associated with a microinflammatory response. Such an association could explain, at least in part, the recently described worse cardiovascular prognosis in individuals with increased HR.

METHODS

Concentrations of fibrinogen and high-sensitivity C-reactive protein, as well as the absolute number of polymorphonuclear leucocytes, were analysed in a cohort of 4553 apparently healthy men and in those with atherothrombotic risk factors.

RESULTS

Following adjustment for age and body mass index, lipid profile and cardiovascular risk factors, a significant (p<0.001) difference was noted between individuals in the first quintile of HR (< or =58 beats/min) and those in the fifth quintile (> or =79 beats/min) regarding all the above-mentioned inflammatory biomarkers, the respective mean values being 7.38 and 8.11 micromol/l, 1.12 and 1.61 mg/l, and 4.23 and 4.74 x 10(9)/l.

CONCLUSIONS

Resting HR is associated with a microinflammatory response in apparently healthy men and in those with atherothrombotic risk factors. Sympathetic activation might be a common factor explaining such an association. If confirmed in additional studies, this association might be a relevant target for therapeutic manipulations.

Exploitation of the nicotinic anti-inflammatory pathway for the treatment of epithelial inflammatory diseases

Discoveries in the first few years of the 21st century have led to an understanding of important interactions between the nervous system and the inflammatory response at the molecular level, most notably the acetylcholine (ACh)-triggered, α7-nicotinic acetylcholine receptor (α7nAChR)-dependent nicotinic anti-inflammatory pathway. Studies using the α7nAChR agonist, nicotine, for the treatment of mucosal inflammation have been undertaken but the efficacy of nicotine as a treatment for inflammatory bowel diseases remains debatable. Further understanding of the nicotinic anti-inflammatory pathway and other endogenous anti-inflammatory mechanisms is required in order to develop refined and specific therapeutic strategies for the treatment of a number of inflammatory diseases and conditions, including periodontitis, psoriasis, sarcoidosis, and ulcerative colitis.

Vagus nerve stimulation inhibits activation of coagulation and fibrinolysis during endotoxemia in rats

BACKGROUND

Sepsis and endotoxemia are associated with concurrent activation of inflammation and the hemostatic mechanism, which both contribute to organ dysfunction and death. Electrical vagus nerve stimulation (VNS) has been found to inhibit tumor necrosis factor (TNF)-alpha release during endotoxemia in rodents.

OBJECTIVE

To determine the effect of VNS on activation of coagulation and fibrinolysis.

METHODS

Rats received a sublethal i.v. dose of lipopolysaccharide (LPS) after electrical VNS or sham stimulation. Activation of coagulation and fibrinolysis, as well as cytokine release, was measured before LPS injection and 2, 4 and 6 h thereafter.

RESULTS

LPS induced activation of the coagulation system (increases in the plasma concentrations of thrombin-antithrombin complexes and D-dimer, and a decrease in antithrombin) and biphasic changes in the fibrinolytic system [early rises of plasminogen activator activity and tissue-type plasminogen activator, followed by a delayed increase in plasminogen activator inhibitor type 1 (PAI-1)]. VNS strongly inhibited all LPS-induced procoagulant responses and more modestly attenuated the fibrinolytic response. In addition, VNS attenuated the LPS-induced increases in plasma and splenic concentrations of the proinflammatory cytokines TNF-alpha and interleukin-6 (IL-6), while not influencing the release of the anti-inflammatory cytokine IL-10.

CONCLUSION

These data illustrate a thus far unrecognized effect of VNS and suggest that the cholinergic anti-inflammatory pathway not only impacts on inflammation but also on the coagulant-anticoagulant balance.

Regulation of peripheral inflammation by spinal p38 MAP kinase in rats

BACKGROUND

Somatic afferent input to the spinal cord from a peripheral inflammatory site can modulate the peripheral response. However, the intracellular signaling mechanisms in the spinal cord that regulate this linkage have not been defined. Previous studies suggest spinal cord p38 mitogen-activated protein (MAP) kinase and cytokines participate in nociceptive behavior. We therefore determined whether these pathways also regulate peripheral inflammation in rat adjuvant arthritis, which is a model of rheumatoid arthritis.

METHODS AND FINDINGS

Selective blockade of spinal cord p38 MAP kinase by administering the p38 inhibitor SB203580 via intrathecal (IT) catheters in rats with adjuvant arthritis markedly suppressed paw swelling, inhibited synovial inflammation, and decreased radiographic evidence of joint destruction. The same dose of SB203580 delivered systemically had no effect, indicating that the effect was mediated by local concentrations in the neural compartment. Evaluation of articular gene expression by quantitative real-time PCR showed that spinal p38 inhibition markedly decreased synovial interleukin-1 and -6 and matrix metalloproteinase (MMP3) gene expression. Activation of p38 required tumor necrosis factor alpha (TNFalpha) in the nervous system because IT etanercept (a TNF inhibitor) given during adjuvant arthritis blocked spinal p38 phosphorylation and reduced clinical signs of adjuvant arthritis.

CONCLUSIONS

These data suggest that peripheral inflammation is sensed by the central nervous system (CNS), which subsequently activates stress-induced kinases in the spinal cord via a TNFalpha-dependent mechanism. Intracellular p38 MAP kinase signaling processes this information and profoundly modulates somatic inflammatory responses. Characterization of this mechanism could have clinical and basic research implications by supporting development of new treatments for arthritis and clarifying how the CNS regulates peripheral immune responses.

Neural-endocrine-immune complex in the central modulation of tumorigenesis: facts, assumptions, and hypotheses

For the precise coordination of systemic functions, the nervous system uses a variety of peripherally and centrally localized receptors, which transmit information from internal and external environments to the central nervous system. Tight interconnections between the immune, nervous, and endocrine systems provide a base for monitoring and consequent modulation of immune system functions by the brain and vice versa. The immune system plays an important role in tumorigenesis. On the basis of rich interconnections between the immune, nervous and endocrine systems, the possibility that the brain may be informed about tumorigenesis is discussed in this review article. Moreover, the eventual modulation of tumorigenesis by central nervous system is also considered. Prospective consequences of the interactions between tumor and brain for diagnosis and therapy of cancer are emphasized.

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.

Anesthesia drugs, immunity, and long-term outcome

PURPOSE OF REVIEW

We provide an overview of the immunological effects of commonly used anesthetic drugs and highlight their potential impact on long-term outcome after surgery.

RECENT FINDINGS

Clinical trials provide preliminary evidence that the perioperative process can influence long-term patient outcome. Immunology may begin to elucidate the biology of this safety concern and open new therapeutic opportunities. In this context, awareness of the immunological properties of drugs administered in the perioperative period may assist in their deliberate use to modulate this risk. Statins, beta-blockers, and clonidine can potentially improve long-term cardiac risk. Volatile anesthetics appear to suppress effector functions of both the innate and adaptive immunity, assist tumor growth in animal models, and facilitate aggregation of certain neurodegenerative disease proteins. Local anesthetics block neurons, but are also potent antiinflammatory drugs. Morphine has recognized immunosuppressive functions, which the newer, synthetic opioids don't seem to share. The cholinergic nervous system has antiinflammatory control functions that are largely unexploited.

SUMMARY

Long-term outcome after surgery is a new safety concern in perioperative care. We are faced with enormous challenges in healthcare and research. As providers, tailoring an anesthetic plan to patients' needs will become increasingly critical, and immunology should help in this pursuit.

The inflammatory reflex and risk for rheumatoid arthritis: a case-control study of human vagotomy

Recent data suggest remarkable effects of vagus stimulation (reduction) and vagotomy (exacerbation) on acute inflammation in rats, the so-called "inflammatory reflex". Its role in humans remains unknown. Therefore, the aim was to explore whether surgical vagotomy in humans would affect the risk of a prototype inflammatory disease, rheumatoid arthritis. This was a case-control study. Assessment of the relative risk (RR) of developing rheumatoid arthritis after surgical vagotomy during 1964-2001 in 63,092 prevalent rheumatoid arthritis cases versus 125,404 matched controls from the general population and in 2548 incident rheumatoid arthritis cases versus 24,357 matched controls from the general population, respectively, was done. For comparison, we assessed RRs for hospitalisation for gastric disorders not including vagotomy. Data on exposures and rheumatoid arthritis were retrieved from population-based and prospectively recorded Swedish registers. A pre-rheumatoid arthritis vagotomy was not significantly associated with an increased risk for rheumatoid arthritis (RR = 1.17, 95% CI 0.97 to 1.40). RRs in the same range were observed for several other pre-rheumatoid arthritis gastric conditions that do not include vagotomy (eg, gastric ulcer RR = 1.21, 95% 1.11 to 1.33). Vagotomy has no specific effect on the risk of developing rheumatoid arthritis in humans. Gastroduodenal ulcers occur more often than expected even before the occurrence of rheumatoid arthritis.

Splenectomy inactivates the cholinergic antiinflammatory pathway during lethal endotoxemia and polymicrobial sepsis

The innate immune system protects against infection and tissue injury through the specialized organs of the reticuloendothelial system, including the lungs, liver, and spleen. The central nervous system regulates innate immune responses via the vagus nerve, a mechanism termed the cholinergic antiinflammatory pathway. Vagus nerve stimulation inhibits proinflammatory cytokine production by signaling through the α7 nicotinic acetylcholine receptor subunit. Previously, the functional relationship between the cholinergic antiinflammatory pathway and the reticuloendothelial system was unknown. Here we show that vagus nerve stimulation fails to inhibit tumor necrosis factor (TNF) production in splenectomized animals during lethal endotoxemia. Selective lesioning of the common celiac nerve abolishes TNF suppression by vagus nerve stimulation, suggesting that the cholinergic pathway is functionally hard wired to the spleen via this branch of the vagus nerve. Administration of nicotine, an α7 agonist that mimics vagus nerve stimulation, increases proinflammatory cytokine production and lethality from polymicrobial sepsis in splenectomized mice, indicating that the spleen is critical to the protective response of the cholinergic pathway. These results reveal a specific, physiological connection between the nervous and innate immune systems that may be exploited through either electrical vagus nerve stimulation or administration of α7 agonists to inhibit proinflammatory cytokine production during infection and tissue injury.

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.

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.

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.

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.

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.

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.

Semapimod Reduces the Depth of Injury Resulting in Enhanced Re-epithelialization of Partial-Thickness Burns in Swine

Studies suggest that tumor necrosis factor alpha (TNF-alpha) plays a role in burn pathogenesis. We conducted a randomized controlled experiment in swine to determine whether a novel macrophage inhibitor, semapimod (formerly known as CNI-1493), would blunt the local production of TNF-alpha, interleukin (IL)-1, and IL-6 in burns leading to less injury extension and faster re-epithelialization. After creating second-degree burns, animals received one or two intravenous boluses of semapimod 1 mg/kg or normal saline, and all burns were treated with silver sulfadiazine. The depth of follicular necrosis and thrombosis was reduced by either one or two doses of semapimod (P=.04 and .02, respectively). However, no differences were noted between groups in cytokine levels. Depth of scarring was similar in all groups. We conclude that Semapimod reduces the depth of follicular necrosis and thrombosis after second-degree burns in swine, indirectly resulting in more rapid re-epithelialization. However, this affect does not appear to be mediated by reduced local TNF-alpha, IL-1, or IL-6 protein levels.

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.

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.

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.