The protective effect of the cholinergic anti-inflammatory pathway against septic shock in rats

Protective Effect of Silymarin on Liver in Experimental in the Sepsis Model of Rats

This study, it was investigated whether silymarin has a protective effect by performing histological, immunohistochemical, and biochemical evaluations on the liver damage induced by cecal ligation perforation (CLP). CLP model was established and silymarin was treated at a dose of 50 mg/kg, 100 mg/kg, and 200 mg/kg, by oral one hour before the CLP. As an effect of the histological evaluations of the liver tissues, venous congestion, inflammation, and necrosis in the hepatocytes were observed in the CLP group. A situation close to the control group was observed in the Silymarin (SM)100 and SM200 groups. As a result of the immunohistochemical evaluations, inducible nitric oxide synthase (iNOS), cytokeratine (CK)18, Tumor necrosis factor-alpha (TNF-α), and interleukine (IL)-6 immunoreactivities were intense in the CLP group. In the biochemical analysis, Alkaline Phosphatase (ALP), Aspartate Aminotransferase (AST), and Alanine Aminotransferase (ALT) levels were significantly increased in the CLP group, while a significant decrease was observed in the treatment groups. TNFα, IL-1β, and IL-6 concentrations were in parallel with histopathological evaluations. In the biochemical analysis, Malondialdehyte (MDA) level increased significantly in the CLP group, but there was a significant decrease in the SM100 and SM200 groups. Glutathione (GSH), Superoxide Dismutase (SOD), Catalase (CAT), and Glutathione Peroxidase (GSH-Px) activities were relatively low in the CLP group. According to these data, it was concluded that using silymarin reduces the existing liver damage in sepsis.

The potential for traditional Chinese therapy in treating sleep disorders caused by COVID-19 through the cholinergic anti-inflammatory pathway

Since the outbreak of Coronavirus disease (COVID-19) in 2019, it has spread rapidly across the globe. Sleep disorders caused by COVID-19 have become a major concern for COVID-19 patients and recovered patients. So far, there’s no effective therapy on this. Traditional Chinese therapy (TCT) has a great effect on sleep disorders, with rare side effects and no obvious withdrawal symptoms. The cholinergic anti-inflammatory pathway, a neuroregulatory pathway in the central nervous system that uses cholinergic neurons and neurotransmitters to suppress inflammatory responses, has been reported to be associated with sleep disorders and psychiatric symptoms. Many studies have shown that TCT activates the cholinergic anti-inflammatory pathway (CAP), inhibits inflammation, and relieves associated symptoms. Therefore, we believe that TCT may be a potential therapeutic strategy to alleviate sleep disorders induced by COVID-19 through CAP. In this review, we analyzed the relationship between cytokine storm induced by Coronavirus and sleep disorders, explained the influence of CAP on sleep disorders, discussed the TCT’s effect on CAP, and summarized the treatment effect of TCT on sleep disorders. Based on these practical researches and theoretical basis, we propose potential strategies to effectively improve the sleep disorders caused by COVID-19.

Non-invasive Vagus Nerve Stimulation for COVID-19: Results From a Randomized Controlled Trial (SAVIOR I)

Background

Severe coronavirus disease 2019 (COVID-19) is characterized, in part, by an excessive inflammatory response. Evidence from animal and human studies suggests that vagus nerve stimulation can lead to reduced levels of various biomarkers of inflammation. We conducted a prospective randomized controlled study (SAVIOR-I) to assess the feasibility, efficacy, and safety of non-invasive vagus nerve stimulation (nVNS) for the treatment of respiratory symptoms and inflammatory markers among patients who were hospitalized for COVID-19 (ClinicalTrials.gov identifier: NCT04368156).

Methods

Participants were randomly assigned in a 1:1 allocation to receive either the standard of care (SoC) alone or nVNS therapy plus the SoC. The nVNS group received 2 consecutive 2-min doses of nVNS 3 times daily as prophylaxis. Efficacy and safety were evaluated via the incidence of specific clinical events, inflammatory biomarker levels, and the occurrence of adverse events.

Results

Of the 110 participants who were enrolled and randomly assigned, 97 (nVNS, n = 47; SoC, n = 50) had sufficient available data and comprised the evaluable population. C-reactive protein (CRP) levels decreased from baseline to a significantly greater degree in the nVNS group than in the SoC group at day 5 and overall (i.e., all postbaseline data points collected through day 5, combined). Procalcitonin level also showed significantly greater decreases from baseline to day 5 in the nVNS group than in the SoC group. D-dimer levels were decreased from baseline for the nVNS group and increased from baseline for the SoC group at day 5 and overall, although the difference between the treatment groups did not reach statistical significance. No significant treatment differences were seen for clinical respiratory outcomes or any of the other biochemical markers evaluated. No serious nVNS-related adverse events occurred during the study.

Conclusions

nVNS therapy led to significant reductions in levels of inflammatory markers, specifically CRP and procalcitonin. Because nVNS has multiple mechanisms of action that may be relevant to COVID-19, additional research into its potential use earlier in the course of COVID-19 and its potential to mitigate some of the symptoms associated with post-acute sequelae of COVID-19 is warranted.

Role of autonomic system imbalance in neurogenic pulmonary oedema

Neurogenic pulmonary oedema (NPE) is a life-threatening complication that develops rapidly and dramatically after an injury to the central nervous system (CNS). The autonomic system imbalance produced by severe brain damage may play an important role in the development of NPE. Activation of the sympathetic nervous system and inhibition of the vagus nerve system are essential prerequisites for autonomic system imbalance. The more severe the damage, the more pronounced the phenomenon. Sympathetic hyperactivity is associated with increased release of catecholamines from peripheral sympathetic nerve endings, which can cause dramatic changes in haemodynamics and cause pulmonary oedema. On the other hand, the abnormal inflammatory response caused by vagus nerve inhibition may also play an important role in the pathogenesis of NPE. The perspective of autonomic system imbalance seems to perfectly integrate the existing pathogenesis of NPE and can explain the entire development progression of NPE.

Increased Concentrations of Circulating Interleukins following Non-Invasive Vagus Nerve Stimulation: Results from a Randomized, Sham-Controlled, Crossover Study in Healthy Subjects

OBJECTIVE

The vagus nerve constitutes the main component of the parasympathetic nervous system and plays an important role in the regulation of neuro-immune responses. Invasive stimulation of the vagus nerve produces anti-inflammatory effects; however, data on humoral immune responses of transcutaneous vagus nerve stimulation (tVNS) are rare. Therefore, the present study investigated changes in serum cytokine concentrations of interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor α (TNFα) following a short-term, non-invasive stimulation of the vagus nerve.

METHODS

Whole blood samples were collected before and after a short-lived application of active tVNS at the inner tragus as well as sham stimulation of the earlobe. Cytokine serum concentrations were determined in two healthy cohorts of younger (n = 20) and older participants (n = 19). Differences between active and sham conditions were analyzed using linear mixed models and post hoc F tests after applying Yeo-Johnson power transformations. This trial was part of a larger study registered on ClinicalTrials.gov (NCT05007743).

RESULTS

In the young cohort, IL-6 and IL-1β concentrations were significantly increased after active stimulation, whereas they were slightly decreased after sham stimulation (IL-6: p = 0.012; IL-1β: p = 0.012). Likewise, in the older cohort, IL-1β and IL-8 concentrations were significantly elevated after active stimulation and reduced after sham application (IL-8: p = 0.007; IL-1β: p = 0.001). In contrast, circulating TNFα concentrations did not change significantly in either group.

CONCLUSION

Our results show that active tVNS led to an immediate increase in the serum concentrations of certain pro-inflammatory cytokines such as IL-1β, IL-6, and/or IL-8 in two independent cohorts of healthy study participants.

Antagonism of Cerebral High Mobility Group Box 1 Ameliorates Dendritic Cell Dysfunction in Sepsis

Sepsis has emerged as a global health issue, and accounts for millions of deaths in intensive care units. Dysregulation of the immune response reportedly contributes to the pathogenesis and progression of this lethal condition, which involves both the dysfunction of immune cells and incompetent immunomodulatory mechanisms. High mobility group box 1 (HMGB1) is known as a later inflammatory mediator and is critically involved in the severity and prognosis of sepsis by inducing intractable inflammation and dysfunction of various immune cells. In the present study, we found that intracerebroventricular (ICV) injection of Box A, a specific antagonist of HMGB1, restored the dysregulated response of splenic dendritic cells (DCs) in septic mice by enhancing the expression of surface molecules, including CD80, CD86, and MHC-II, as well as improving DC priming of T lymphocytes. Cerebral HMGB1 was also confirmed to have potent inhibitory effects on DC functions when administrated by ICV injection in normal mice. The brain cholinergic system was found to mediate the immunomodulatory effects of central HMGB1, as it exhibited enhanced activity with persistent HMGB1 exposure. Furthermore, the inhibitory effects of cerebral HMGB1 on the response of peripheral DCs were also blocked by α7nAchR gene knockout. These findings provide novel insight into the relationship between cerebral HMGB1 and splenic DC dysfunction during sepsis, which is, at least in part, dependent on cholinergic system activity.

Increased mortality and altered local immune response in secondary peritonitis after previous visceral operations in mice

Postoperative peritonitis is characterized by a more severe clinical course than other forms of secondary peritonitis. The pathophysiological mechanisms behind this phenomenon are incompletely understood. This study used an innovative model to investigate these mechanisms, combining the models of murine Colon Ascendens Stent Peritonitis (CASP) and Surgically induced Immune Dysfunction (SID). Moreover, the influence of the previously described anti-inflammatory reflex transmitted by the vagal nerve was characterized. SID alone, or 3 days before CASP were performed in female C57BL/6 N mice. Subdiaphragmatic vagotomy was performed six days before SID with following CASP. The immune status was assessed by FACS analysis and measurement of cytokines. Local intestinal inflammatory changes were characterized by immunohistochemistry. Mortality was increased in CASP animals previously subjected to SID. Subclinical bacteremia occurred after SID, and an immunosuppressive milieu occurred secondary to SID just before the induction of CASP. Previous SID modified the pattern of intestinal inflammation induced by CASP. Subdiaphragmatic vagotomy had no influence on sepsis mortality in our model of postoperative peritonitis. Our results indicate a surgery-induced inflammation of the small intestine and the peritoneal cavity with bacterial translocation, which led to immune dysfunction and consequently to a more severe peritonitis.

PNU-282987 Attenuates Intestinal Epithelial Barrier Dysfunction in LPS-Induced Endotoxemia

PNU-282987, the α7 acetylcholine receptor(α7nAchR) agonist, has been repeatedly reported to play a key role in anti-inflammatory action of multiple disease. However, little is known about its effect on LPS-induced intestinal epithelial barrier dysfunction. This study investigated the protective effects and mechanisms of PNU-282987 on intestinal epithelial barrier dysfunction in lipopolysaccharide(LPS)-induced endotoxemic rats. Endotoxemia models were induced by intraperitoneal injection of 10 mg/kg LPS. In the endotoxemic group, results showed increases in ileum mucosal permeability, ultrastructural damage of tight junction and redistribution of zonula occludens-1, apoptosis of intestinal epithelial cells and caspase-3 activation. These changes were significantly improved after PNU-282987 administration(P < 0.05). Pretreatment with α-bungarotoxin before PNU-282987 administration reversed the effects of PNU-282987(P < 0.05). These results indicate that PNU-282987 exerts protective effects on intestinal epithelial barrier dysfunction in LPS-induced endotoxemic rats, and its mechanism may involve the improvement of zonula occludens-1 and inhibition of enterocyte apoptosis in an α7nAchR-dependent manner.

Implications for Neuromodulation Therapy to Control Inflammation and Related Organ Dysfunction in COVID-19

COVID-19 is a syndrome that includes more than just isolated respiratory disease, as severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) also interacts with the cardiovascular, nervous, renal, and immune system at multiple levels, increasing morbidity in patients with underlying cardiometabolic conditions and inducing myocardial injury or dysfunction. Emerging evidence suggests that patients with the highest rate of morbidity and mortality following SARS-CoV2 infection have also developed a hyperinflammatory syndrome (also termed cytokine release syndrome). We lay out the potential contribution of a dysfunction in autonomic tone to the cytokine release syndrome and related multiorgan damage in COVID-19. We hypothesize that a cholinergic anti-inflammatory pathway could be targeted as a therapeutic avenue. Graphical Abstract .

Identification of circRNA and mRNA expression profiles and functional networks of vascular tissue in lipopolysaccharide-induced sepsis

Sepsis is the most common cause of death in intensive care units. This study investigated the circular RNA (circRNA) and mRNA expression profiles and functional networks of the aortic tissue in sepsis. We established a lipopolysaccharide (LPS)‐induced rat sepsis model. High‐throughput sequencing was performed on the aorta tissue to identify differentially expressed (DE) circRNAs and mRNAs, which were validated by real‐time quantitative polymerase chain reaction (RT‐qPCR). Bioinformatic analysis was carried out and coding and non‐coding co‐expression (CNC) and competing endogenous RNA (ceRNA) regulatory networks were constructed to investigate the mechanisms. In total, 373 up‐regulated and 428 down‐regulated circRNAs and 2063 up‐regulated and 2903 down‐regulated mRNAs were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of mRNAs showed that the down‐regulated genes were mainly enriched in the process of energy generation. CNC and ceRNA regulatory networks were constructed with seven DE circRNAs. The results of functional enrichment analysis of CNC target genes revealed the important role of circRNAs in inflammatory response. The ceRNA network also highlighted the significant enrichment in calcium signalling pathway. Significant alterations in circRNAs and mRNAs were observed in the aortic tissue of septic rats. In addition, CNC and ceRNA networks were established.

Vagus Nerve Stimulation Attenuates Multiple Organ Dysfunction in Resuscitated Porcine Progressive Sepsis

OBJECTIVES

To investigate the potential benefits of vagus nerve stimulation in a clinically-relevant large animal model of progressive sepsis.

DESIGN

Prospective, controlled, randomized trial.

SETTING

University animal research laboratory.

SUBJECTS

Twenty-five domestic pigs were divided into three groups: 1) sepsis group (eight pigs), 2) sepsis + vagus nerve stimulation group (nine pigs), and 3) control sham group (eight pigs).

INTERVENTIONS

Sepsis was induced by cultivated autologous feces inoculation in anesthetized, mechanically ventilated, and surgically instrumented pigs and followed for 24 hours. Electrical stimulation of the cervical vagus nerve was initiated 6 hours after the induction of peritonitis and maintained throughout the experiment.

MEASUREMENTS AND MAIN RESULTS

Measurements of hemodynamics, electrocardiography, biochemistry, blood gases, cytokines, and blood cells were collected at baseline (just before peritonitis induction) and at the end of the in vivo experiment (24 hr after peritonitis induction). Subsequent in vitro analyses addressed cardiac contractility and calcium handling in isolated tissues and myocytes and analyzed mitochondrial function by ultrasensitive oxygraphy. Vagus nerve stimulation partially or completely prevented the development of hyperlactatemia, hyperdynamic circulation, cellular myocardial depression, shift in sympathovagal balance toward sympathetic dominance, and cardiac mitochondrial dysfunction, and reduced the number of activated monocytes. Sequential Organ Failure Assessment scores and vasopressor requirements significantly decreased after vagus nerve stimulation.

CONCLUSIONS

In a clinically-relevant large animal model of progressive sepsis, vagus nerve stimulation was associated with a number of beneficial effects that resulted in significantly attenuated multiple organ dysfunction and reduced vasopressor and fluid resuscitation requirements. This suggests that vagus nerve stimulation might provide a significant therapeutic potential that warrants further thorough investigation.

Mechanisms and treatment of organ failure in sepsis

Sepsis is a dysregulated immune response to an infection that leads to organ dysfunction. Knowledge of the pathophysiology of organ failure in sepsis is crucial for optimizing the management and treatment of patients and for the development of potential new therapies. In clinical practice, six major organ systems - the cardiovascular (including the microcirculation), respiratory, renal, neurological, haematological and hepatic systems - can be assessed and monitored, whereas others, such as the gut, are less accessible. Over the past 2 decades, considerable amounts of new data have helped improve our understanding of sepsis pathophysiology, including the regulation of inflammatory pathways and the role played by immune suppression during sepsis. The effects of impaired cellular function, including mitochondrial dysfunction and altered cell death mechanisms, on the development of organ dysfunction are also being unravelled. Insights have been gained into interactions between key organs (such as the kidneys and the gut) and organ-organ crosstalk during sepsis. The important role of the microcirculation in sepsis is increasingly apparent, and new techniques have been developed that make it possible to visualize the microcirculation at the bedside, although these techniques are only research tools at present.

Inhibition of Cerebral High-Mobility Group Box 1 Protein Attenuates Multiple Organ Damage and Improves T Cell-Mediated Immunity in Septic Rats

Sepsis remains one of the leading causes of mortality in intensive care units, but there is a shortage of effective treatments. A dysregulated host immune response and multiple organ injury are major factors for the pathogenesis and progression of sepsis, which require specific mechanism and treatment. In the present study, we performed an intracerebroventricular (ICV) injection of BoxA, a specific antagonist of high-mobility group box 1 protein (HMGB1), in septic rats that were produced by cecal ligation and puncture surgery; we further assessed the functional changes of multiple organs and splenic T lymphocytes. We found that the inhibition of cerebral HMGB1 significantly alleviated multiple organ damage under septic exposure, including damage to the heart, liver, lungs, and kidneys; reversed the immune dysfunction of T cells; and increased the survival of septic rats. These data suggest that central HMGB1 might be a potential therapeutic target for septic challenge and that inhibition of brain HMGB1 can protect against multiple organ dysfunction induced by sepsis.

Repurposing Pilocarpine Hydrochloride for Treatment of Candida albicans Infections

Candida albicans is the most common human fungal pathogen with an estimated crude mortality rate of 40%. The ability of the organism to switch from the yeast to hyphal form and produce biofilms are important virulence factors. C. albicans infections are combatted by the host immune system. However, Candida triggers a strong inflammatory response that, if not appropriately regulated, can damage host tissues. Therefore, it is important that the host immune response eliminates the fungus but limits tissue damage. This study provides evidence that targeting cholinergic receptors cannot only curb the virulence of C. albicans by inhibiting filamentous growth and biofilm formation but can also appropriately regulate the host immune response to induce rapid clearance with limited damage to vital tissues. This article provides evidence that repurposing licensed drugs that target cholinergic receptors may offer novel therapeutic solutions for the prevention or treatment of fungal infections.

Acetylcholine modulates the virulence of Candida albicans and regulates an appropriate immune response to infection in a Galleria mellonella infection model. Indeed, the evidence suggests that C. albicans possesses a functional cholinergic receptor that can regulate filamentous growth and biofilm formation. Furthermore, G. mellonella immune cell subsets possess repertories of cholinergic receptors which regulate an effective and appropriate cellular immune response to C. albicans infection. This study aimed to investigate the cholinergic receptor subtype involved in regulation of filamentous growth and biofilm formation by C. albicans and determine the roles of cholinergic receptors in modulation of G. mellonella immune cell subsets. The general muscarinic receptor agonist, pilocarpine hydrochloride, inhibited C. albicans biofilm formation and pathogenicity, a phenomenon that could be reversed using the general muscarinic receptor antagonist, scopolamine. Pilocarpine hydrochloride protected G. mellonella larvae from C. albicans infection via inhibition of C. albicans filamentation and appropriate regulation of cellular immunity. However, scopolamine abrogated the capacity of pilocarpine hydrochloride to protect G. mellonella larvae from C. albicans infection. Furthermore, acetylcholine and pilocarpine hydrochloride exhibited differential modulatory capabilities on Galleria mellonella hemocyte responses to C. albicans. The data in this article demonstrate that a muscarinic receptor modulates C. albicans filamentation and biofilm formation. Furthermore, the results suggest that G. mellonella hemocyte subsets possess unique repertoires of cholinergic receptors that regulate their differentiation, activation, and function in contrasting manners. Therefore, targeting cholinergic receptors by repurposing currently licensed cholinergic drugs may offer novel therapeutic solutions for the prevention or treatment of fungal infections.

IMPORTANCECandida albicans is the most common human fungal pathogen with an estimated crude mortality rate of 40%. The ability of the organism to switch from the yeast to hyphal form and produce biofilms are important virulence factors. C. albicans infections are combatted by the host immune system. However, Candida triggers a strong inflammatory response that, if not appropriately regulated, can damage host tissues. Therefore, it is important that the host immune response eliminates the fungus but limits tissue damage. This study provides evidence that targeting cholinergic receptors cannot only curb the virulence of C. albicans by inhibiting filamentous growth and biofilm formation but can also appropriately regulate the host immune response to induce rapid clearance with limited damage to vital tissues. This article provides evidence that repurposing licensed drugs that target cholinergic receptors may offer novel therapeutic solutions for the prevention or treatment of fungal infections.

SOCS3 participates in cholinergic pathway regulation of synovitis in rheumatoid arthritis

Stimulation of the cholinergic inflammatory pathway can attenuate collagen-induced arthritis (CIA) and inhibit synovitis by Janus kinase (JAK) 2 and signal transducer and activator of transcription (STAT) 3 signaling. Suppressor of cytokine signaling (SOCS) protein can also regulate the inflammatory processes and activate JAK/STAT signal transduction, but its involvement in rheumatoid arthritis (RA) has not been demonstrated. This study investigated the effect of SOCS on cholinergic pathway regulation of synovitis in the fibroblast-like synoviocytes (FLSs) of RA and CIA mice. The effects of nicotine on SOCS1 and SOCS3 protein expression in FLSs were assayed by western blotting before and after transfection with a small interfering RNA oligonucleotide (SOCS3-siRNA or control-siRNA). Interleukin-6 was measured by enzyme-linked immunosorbent assay of SOCS3-siRNA and control-siRNA transfected FLS culture supernatants. Histopathological evaluation and immunohistochemical staining of SOCS3 were performed in joint tissue sections of control, CIA model, vagotomy, and nicotine-treated DBA/1 mice. Nicotine increased SOCS3 expression in the FLSs of RA. The inhibitory effect of nicotine on inflammatory factors was abolished by siRNA knockdown of SOCS3 protein expression. Nicotine increased the expression of SOCS3 protein in the synovium and reduced synovitis and bone erosion in CIA mice.

Eyeing up the Future of the Pupillary Light Reflex in Neurodiagnostics

The pupillary light reflex (PLR) describes the constriction and subsequent dilation of the pupil in response to light as a result of the antagonistic actions of the iris sphincter and dilator muscles. Since these muscles are innervated by the parasympathetic and sympathetic nervous systems, respectively, different parameters of the PLR can be used as indicators for either sympathetic or parasympathetic modulation. Thus, the PLR provides an important metric of autonomic nervous system function that has been exploited for a wide range of clinical applications. Measurement of the PLR using dynamic pupillometry is now an established quantitative, non-invasive tool in assessment of traumatic head injuries. This review examines the more recent application of dynamic pupillometry as a diagnostic tool for a wide range of clinical conditions, varying from neurodegenerative disease to exposure to toxic chemicals, as well as its potential in the non-invasive diagnosis of infectious disease.

Role of Cholinergic Anti-Inflammatory Pathway in Treatment of Intestinal Ischemia-Reperfusion Injury by Electroacupuncture at Zusanli

Electroacupuncture (EA) at Zusanli is a widely used method for the treatment of intestinal ischemic disease. The current study attempts to investigate the possible mechanism from the point of cholinergic anti-inflammatory pathway (CAP) in rats. Thirty rats were divided into five groups: control group, I/R group, EA group (I/R + EA), PNU group (I/R + α7 nAChR agonist), and α-BGT group (I/R + EA + α7 nAChR antagonist). EA and medicine injection were performed immediately after ischemia. After 2 h of reperfusion, blood and intestine samples were collected and intestinal histopathological score, mRNA expression of mucosal α7 nAChR and NF-κBp65, and serum cytokine levels (IL-6, TNF-α) were examined. Compared with the I/R group, the EA group and PNU group could significantly attenuate the mucosal damage, promote α7 nAChR mRNA expression, and reduce levels of NF-κBp65, IL-6, and TNF-α. Compared with the EA group, α7 nAChR mRNA was decreased, while concentrations of NF-κBp65, IL-6, and TNF-α increased in the α-BGT group. EA at Zusanli could inhibit NF-κBp65 and proinflammatory cytokines production after intestinal I/R injury; its mechanism may be related to the cholinergic anti-inflammatory pathway.

Electroacupuncture improves acute bowel injury recovery in rat models

Electroacupuncture (EA) accelerates intestinal functional recovery in sepsis. The present study investigated ghrelin and ghrelin receptor (GSH-R) levels during EA in rats with acute bowel injury (ABI). Rats were grouped into four groups: Sham, ABI, ABI+EA and ABI+GHRA+EA (n=12 per group). ABI was induced by cecal ligation and puncture (CLP). EA on bilateral Zusanli acupoints was performed following CLP. GSH-R blocker (GHRA) was used following CLP but prior to EA for ABI+GHRA+EA rats. Rats were sacrificed 12 h following CLP. Serum ghrelin, tumor necrosis factor-α (TNF-α) and high mobility group box 1 (HMGB1) levels, as well as ghrelin and GSH-R protein expression, water content, pathological changes and myeloperoxidase (MPO) and diamine oxidase (DAO) activities in the bowel tissues, were measured. ABI rats, compared with the sham rats, had significantly lower levels of ghrelin and GSH-R in the serum and bowel tissue, and higher Chiu's score (all P<0.05). The ABI+EA rats, compared with the ABI rats, had significantly reduced serum TNF-α and HMGB1 levels, bowel water content, MPO activity and Chiu's score (all P<0.05), and significantly higher serum ghrelin (121.2±10.7 vs. 86.7±6.4 pg/ml), bowel ghrelin (0.12±0.02 vs. 0.08±0.01), GSH-R (0.05±0.04 vs. 0.03±0.01) and DAO activity (18.74±4.18 vs. 13.52±2.33 U/ml; all P<0.05), indicating an improvement of the intestinal mucosal barrier. GHRA reversed the protective effects of EA. Therefore, EA improved ABI recovery by promoting ghrelin secretion and upregulating GSH-R expression.

The immune system's role in sepsis progression, resolution, and long-term outcome

Sepsis occurs when an infection exceeds local tissue containment and induces a series of dysregulated physiologic responses that result in organ dysfunction. A subset of patients with sepsis progress to septic shock, defined by profound circulatory, cellular, and metabolic abnormalities, and associated with a greater mortality. Historically, sepsis-induced organ dysfunction and lethality were attributed to the complex interplay between the initial inflammatory and later anti-inflammatory responses. With advances in intensive care medicine and goal-directed interventions, early 30-day sepsis mortality has diminished, only to steadily escalate long after "recovery" from acute events. As so many sepsis survivors succumb later to persistent, recurrent, nosocomial, and secondary infections, many investigators have turned their attention to the long-term sepsis-induced alterations in cellular immune function. Sepsis clearly alters the innate and adaptive immune responses for sustained periods of time after clinical recovery, with immune suppression, chronic inflammation, and persistence of bacterial representing such alterations. Understanding that sepsis-associated immune cell defects correlate with long-term mortality, more investigations have centered on the potential for immune modulatory therapy to improve long-term patient outcomes. These efforts are focused on more clearly defining and effectively reversing the persistent immune cell dysfunction associated with long-term sepsis mortality.

Vagal Modulation of the Inflammatory Response in Sepsis

The vagus nerve can sense peripheral inflammation and transmit action potentials from the periphery to the brainstem. Vagal afferent signaling is integrated in the brainstem, and efferent vagus nerves carry outbound signals that terminate in spleen and other organs. Stimulation of efferent vagus nerve leads to the release of acetylcholine in these organs. In turn, acetylcholine interacts with members of the nicotinic acetylcholine receptor (nAChR) family, particularly with the alpha7 nicotinic acetylcholine receptor (α7nAChR), which is expressed by macrophages and other cytokine-producing cells. Ultimately, the production of proinflammatory cytokines is markedly inhibited. This neuroimmune communication is termed "the inflammatory reflex". The uncontrolled inflammation as a result from sepsis can lead to multiple organ failure, and even death. Experimental data show that regulation of the inflammatory reflex appears to be a useful interventional strategy for septic response. Herein, we review recent advances in the understanding of the inflammatory reflex and discuss potential therapeutics that vagal modulation of the immune system for the treatment of severe sepsis and septic shock.

Remifentanil attenuates lipopolysaccharide-induced acute lung injury by downregulating the NF-κB signaling pathway

Remifentanil significantly represses cell immune responses and influences neutrophil migration through endothelial cell monolayers. The present study determines the beneficial effects of remifentanil and the mechanisms by which it attenuates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Rats were intratracheally instilled with 2 mg/kg LPS to induce ALI. Results showed that remifentanil could resolve lung injury, as evidenced by remarkable decreases in lung edema (wet-to-dry weight ratio), neutrophil infiltration (myeloperoxidase activity), and pulmonary permeability [total number of cells and protein concentrations in bronchoalveolar lavage fluid (BALF)]. Remifentanil also attenuated the concentrations of proinflammatory cytokines tumor necrosis factor alpha, interleukin-1β, and interleukin-6 in BALF, as well as effectively repressed the activation of nuclear factor-kappaB (NF-κB), which has been associated with the inhibition of IκBα degradation.These results suggest that remifentanil may be a suitable treatment for LPS-induced ALI. Remifentanil exerts beneficial effects on the inhibition of proinflammatory cytokine production by downregulating the NF-κB pathway.

Transvenous vagus nerve stimulation does not modulate the innate immune response during experimental human endotoxemia: a randomized controlled study

INTRODUCTION

Vagus nerve stimulation (VNS) exerts beneficial anti-inflammatory effects in various animal models of inflammation, including collagen-induced arthritis, and is implicated in representing a novel therapy for rheumatoid arthritis. However, evidence of anti-inflammatory effects of VNS in humans is very scarce. Transvenous VNS (tVNS) is a newly developed and less invasive method to stimulate the vagus nerve. In the present study, we determined whether tVNS is a feasible and safe procedure and investigated its putative anti-inflammatory effects during experimental human endotoxemia.

METHODS

We performed a randomized double-blind sham-controlled study in healthy male volunteers. A stimulation catheter was inserted in the left internal jugular vein at spinal level C5-C7, adjacent to the vagus nerve. In the tVNS group (n = 10), stimulation was continuously performed for 30 minutes (0-10 V, 1 ms, 20 Hz), starting 10 minutes before intravenous administration of 2 ng kg(-1) Escherichia coli lipopolysaccharide (LPS). Sham-instrumented subjects (n = 10) received no electrical stimulation.

RESULTS

No serious adverse events occurred throughout the study. In the tVNS group, stimulation of the vagus nerve was achieved as indicated by laryngeal vibration. Endotoxemia resulted in fever, flu-like symptoms, and hemodynamic changes that were unaffected by tVNS. Furthermore, plasma levels of inflammatory cytokines increased sharply during endotoxemia, but responses were similar between groups. Finally, cytokine production by leukocytes stimulated with LPS ex vivo, as well as neutrophil phagocytosis capacity, were not influenced by tVNS.

CONCLUSIONS

tVNS is feasible and safe, but does not modulate the innate immune response in humans in vivo during experimental human endotoxemia.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01944228. Registered 12 September 2013.

Pulmonary inflammation is regulated by the levels of the vesicular acetylcholine transporter

Acetylcholine (ACh) plays a crucial role in physiological responses of both the central and the peripheral nervous system. Moreover, ACh was described as an anti-inflammatory mediator involved in the suppression of exacerbated innate response and cytokine release in various organs. However, the specific contributions of endogenous release ACh for inflammatory responses in the lung are not well understood. To address this question we have used mice with reduced levels of the vesicular acetylcholine transporter (VAChT), a protein required for ACh storage in secretory vesicles. VAChT deficiency induced airway inflammation with enhanced TNF-α and IL-4 content, but not IL-6, IL-13 and IL-10 quantified by ELISA. Mice with decreased levels of VAChT presented increased collagen and elastic fibers deposition in airway walls which was consistent with an increase in inflammatory cells positive to MMP-9 and TIMP-1 in the lung. In vivo lung function evaluation showed airway hyperresponsiveness to methacholine in mutant mice. The expression of nuclear factor-kappa B (p65-NF-kB) in lung of VAChT-deficient mice were higher than in wild-type mice, whereas a decreased expression of janus-kinase 2 (JAK2) was observed in the lung of mutant animals. Our findings show the first evidence that cholinergic deficiency impaired lung function and produce local inflammation. Our data supports the notion that cholinergic system modulates airway inflammation by modulation of JAK2 and NF-kB pathway. We proposed that intact cholinergic pathway is necessary to maintain the lung homeostasis.

Neural reflex regulation of systemic inflammation: potential new targets for sepsis therapy

Sepsis progresses to multiple organ dysfunction due to the uncontrolled release of inflammatory mediators, and a growing body of evidence shows that neural signals play a significant role in modulating the immune response. Thus, similar toall other physiological systems, the immune system is both connected to and regulated by the central nervous system. The efferent arc consists of the activation of the hypothalamic–pituitary–adrenal axis, sympathetic activation, the cholinergic anti-inflammatory reflex, and the local release of physiological neuromodulators. Immunosensory activity is centered on the production of pro-inflammatory cytokines, signals that are conveyed to the brain through different pathways. The activation of peripheral sensory nerves, i.e., vagal paraganglia by the vagus nerve, and carotid body (CB) chemoreceptors by the carotid/sinus nerve are broadly discussed here. Despite cytokine receptor expression in vagal afferent fibers, pro-inflammatory cytokines have no significant effect on vagus nerve activity. Thus, the CB may be the source of immunosensory inputs and incoming neural signals and, in fact, sense inflammatory mediators, playing a protective role during sepsis. Considering that CB stimulation increases sympathetic activity and adrenal glucocorticoids release, the electrical stimulation of arterial chemoreceptors may be suitable therapeutic approach for regulating systemic inflammation.

Vagus nerve through α7 nAChR modulates lung infection and inflammation: models, cells, and signals

Cholinergic anti-inflammatory pathway (CAP) bridges immune and nervous systems and plays pleiotropic roles in modulating inflammation in animal models by targeting different immune, proinflammatory, epithelial, endothelial, stem, and progenitor cells and signaling pathways. Acute lung injury (ALI) is a devastating inflammatory disease. It is pathogenically heterogeneous and involves many cells and signaling pathways. Here, we emphasized the research regarding the modulatory effects of CAP on animal models, cell population, and signaling pathways that involved in the pathogenesis of ALI. By comparing the differential effects of CAP on systemic and pulmonary inflammation, we postulated that a pulmonary parasympathetic inflammatory reflex is formed to sense and respond to pathogens in the lung. Work targeting the formation and function of pulmonary parasympathetic inflammatory reflex would extend our understanding of how vagus nerve senses, recognizes, and fights with pathogens and inflammatory responses.

Vagal efferent fiber stimulation ameliorates pulmonary microvascular endothelial cell injury by downregulating inflammatory responses

Electrical stimulation of the vagus nerve may have positive effects on many inflammatory diseases. This study determined the beneficial effects of vagus nerve stimulation and the mechanisms by which it attenuates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Rats were intraperitoneally injected with 10 mg/kg LPS to induce ALI. The results showed that vagus nerve stimulation could improve lung injury, as evidenced by remarkable reductions in lung edema (wet-to-dry weight ratio), neutrophil infiltration (myeloperoxidase activity), and pulmonary permeability [total number of cells and protein concentrations in bronchoalveolar lavage fluid (BALF)]. In addition, vagus nerve stimulation not only decreased the expressions of Src-suppressed C kinase substrate and E-selectin proteins in lung tissue but also effectively attenuated the concentrations of the proinflammatory cytokines tumor necrosis factor-α, interleukin-1β, and interleukin-6 in BALF. These suggest that vagus nerve stimulation is a suitable treatment for LPS-induced ALI and indicate that it helps ameliorate pulmonary microvascular endothelial cell injury by downregulating inflammatory responses.

Vagus nerve stimulation attenuates intestinal epithelial tight junctions disruption in endotoxemic mice through α7 nicotinic acetylcholine receptors

We tested the effect of vagus nerve stimulation in endotoxin-induced intestinal tight junction injury in mice challenged with lipopolysaccharide (LPS) and examined the role of α7 nicotinic acetylcholine receptors (α7nAchR) in this process. Endotoxemia was induced by intraperitoneal injection of LPS (10 mg/kg) in male Balb/c mice. Samples were collected 12 h after LPS treatment. Endotoxemia was associated with intestinal barrier dysfunction, as evidenced by increased amount of fluorescein isothiocyanate-dextran in circulation. Western blot and immunofluorescence was performed, and the results demonstrated decreased expression of occludin and zonula occludens 1 along intestinal epithelium in endotoxemic mice. The ultrastructure of tight junction was disrupted as shown by transmission electron microscopy, which was associated with increased intestinal permeability. Stimulation of the right cervical vagus nerve ameliorated the damage of tight junction ultrastructure, which was consistent with decreased permeability to fluorescein isothiocyanate-dextran, and also reversed the decreased expression of tight junction proteins occludin and zonula occludens 1. Vagus nerve stimulation inhibited the upregulated activity of myosin light chain kinase and nuclear factor κB. In contrast, α-bungarotoxin (a specific α7nAchR antagonist, 0.1 μg/mouse) administered before vagus nerve stimulation significantly abolished these protective effects of vagus nerve stimulation. Our results for the first time confirmed that vagus nerve stimulation attenuated the disruption of tight junction in intestinal epithelium in endotoxemic mice, which was mediated through suppressing translocation of nuclear factor κB p65, downregulating myosin light chain kinase, and the α7nAchR may play an important role in this process.

Novel therapeutic targets for sepsis: regulation of exaggerated inflammatory responses

Sepsis is a devastating and complex syndrome and continues to be a major cause of morbidity and mortality among critically ill patients at the surgical intensive care unit setting in the United States. The occurrence of sepsis and septic shock has increased significantly over the past two decades. Despite of highly dedicated basic research and numerous clinical trials, remarkable progress has not been made in the development of novel and effective therapeutics. The sepsis-induced physiologic derangements are due largely to the host responses to the invading microorganism in contrast to the direct effects of the microorganism itself. Sepsis, the systemic inflammatory response to infection, is marked by dysregulated production of pro-inflammatory cytokines. Although pro-inflammatory cytokine production is normally indispensable to protect against pathogens and promote tissue repair, the dysregulated and prolonged production of these cytokines can trigger a systemic inflammatory cascade mediated by chemokines, vasoactive amines, the complement and coagulation system, and reactive oxygen species (ROS), amongst others. These mediators collectively lead to multiple organ failure, and ultimately to death. In this regard, the role of inflammation in the pathophysiology of sepsis, although still incompletely understood, is clearly critical. Recent findings resulting from vigorous investigations have contributed to delineate various novel directions of sepsis therapeutics. Among these, this review article is focused on new promising mechanisms and concepts that could have a key role in anti-inflammatory strategies against sepsis, including 1) "inflammasome": a multiprotein complex that activates caspase-1; 2) "the cholinergic anti-inflammatory pathway": the efferent arm of the vagus nerve-mediated, brain-to-immune reflex; 3) "stem cells": unspecialized and undifferentiated precursor cells with the capacity for self-renewal and potential to change into cells of multiple lineages; 4) "milk fat globule-EGF factor VIII (MFG-E8)": a bridging molecule between apoptotic cells and phagocytes, which promotes phagocytosis of apoptotic cells.

Targeting the "cytokine storm" for therapeutic benefit

Inflammation is the body's first line of defense against infection or injury, responding to challenges by activating innate and adaptive responses. Microbes have evolved a diverse range of strategies to avoid triggering inflammatory responses. However, some pathogens, such as the influenza virus and the Gram-negative bacterium Francisella tularensis, do trigger life-threatening "cytokine storms" in the host which can result in significant pathology and ultimately death. For these diseases, it has been proposed that downregulating inflammatory immune responses may improve outcome. We review some of the current candidates for treatment of cytokine storms which may prove useful in the clinic in the future and compare them to more traditional therapeutic candidates that target the pathogen rather than the host response.

Transcutaneous auricular vagus nerve stimulation protects endotoxemic rat from lipopolysaccharide-induced inflammation

Background. Transcutaneous auricular vagus nerve stimulation (ta-VNS) could evoke parasympathetic activities via activating the brainstem autonomic nuclei, similar to the effects that are produced after vagus nerve stimulation (VNS). VNS modulates immune function through activating the cholinergic anti-inflammatory pathway. Methods. VNS, ta-VNS, or transcutaneous electrical acupoint stimulation (TEAS) on ST36 was performed to modulate the inflammatory response. The concentration of serum proinflammatory cytokines and tissue NF-kappa B p65 (NF-κB p65) were detected in endotoxaemia affected anesthetized rats. Results. Similar to the effect of VNS, ta-VNS suppressed the serum proinflammatory cytokines levels, such as tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) as well as NF-kappa B p65 expressions of lung tissues. ST36 stimulation also decreases LPS-induced high TNF-α level and NF-κB signal, but it did not restrain proinflammatory cytokine IL-1β and IL-6. Neither ta-VNS nor ST36 stimulation could suppress LPS-induced TNF-α and NF-κB after vagotomy or with α7nAChR antagonist injection. Conclusions. The present paper demonstrated that ta-VNS could be utilized to suppress LPS-induced inflammatory responses via α7nAChR-mediated cholinergic anti-inflammatory pathway.

Rethinking inflammation: neural circuits in the regulation of immunity

Neural reflex circuits regulate cytokine release to prevent potentially damaging inflammation and maintain homeostasis. In the inflammatory reflex, sensory input elicited by infection or injury travels through the afferent vagus nerve to integrative regions in the brainstem, and efferent nerves carry outbound signals that terminate in the spleen and other tissues. Neurotransmitters from peripheral autonomic nerves subsequently promote acetylcholine-release from a subset of CD4(+) T cells that relay the neural signal to other immune cells, e.g. through activation of α7 nicotinic acetylcholine receptors on macrophages. Here, we review recent progress in the understanding of the inflammatory reflex and discuss potential therapeutic implications of current findings in this evolving field.

Carbachol ameliorates lipopolysaccharide-induced intestinal epithelial tight junction damage by down-regulating NF-κβ and myosin light-chain kinase pathways

Carbachol is a cholinergic agonist that protects the intestines after trauma or burn injury. The present study determines the beneficial effects of carbachol and the mechanisms by which it ameliorates the lipopolysaccharide (LPS)-induced intestinal barrier breakdown. Rats were injected intraperitoneally with 10 mg/kg LPS. Results showed that the gut barrier permeability was reduced, the ultrastructural disruption of tight junctions (TJs) was prevented, the redistribution of zonula occludens-1 and claudin-2 proteins was partially reversed, and the nuclear factor-kappa beta (NF-κβ) and myosin light-chain kinase (MLCK) activation in the intestinal epithelium were suppressed after carbachol administration in LPS-exposed rats. Pretreatment with the α7 nicotinic acetylcholine receptor (α7nAchR) antagonist α-bungarotoxin blocked the protective action of carbachol. These results suggested that carbachol treatment can protect LPS-induced intestinal barrier dysfunction. Carbachol exerts its beneficial effect on the amelioration of the TJ damage by inhibiting the NF-κβ and MLCK pathways in an α7nAchR-dependent manner.

The vagus nerve and the inflammatory reflex: wandering on a new treatment paradigm for systemic inflammation and sepsis

BACKGROUND

The immune system protects the host against dangerous pathogens and toxins. The central nervous system is charged with monitoring and coordinating appropriate responses to internal and external stimuli. The inflammatory reflex sits at the crossroads of these crucial homeostatic systems. This review highlights how the vagus nerve-mediated inflammatory reflex facilitates rapid and specific exchange of information between the nervous and immune systems to prevent tissue injury and infection.

METHODS

Review of the pertinent English-language literature. Nearly two decades of research has elucidated some of the essential anatomic, physiologic, and molecular connections of the inflammatory reflex. The original descriptions of how these key components contribute to afferent and efferent anti-inflammatory vagus nerve signaling are summarized.

RESULTS

The central nervous system recognizes peripheral inflammation via afferent vagus nerve signaling. The brain can attenuate peripheral innate immune responses, including pro-inflammatory cytokine production, leukocyte recruitment, and nuclear factor kappa β activation via α7-nicotinic acetylcholine receptor subunit-dependent, T-lymphocyte-dependent, vagus nerve signaling to spleen. This efferent arm of the inflammatory reflex is referred to as the "cholinergic anti-inflammatory pathway." Activation of this pathway via vagus nerve stimulation or pharmacologic α7 agonists prevents tissue injury in multiple models of systemic inflammation, shock, and sepsis.

CONCLUSIONS

The vagus nerve-mediated inflammatory reflex is a powerful ally in the fight against lethal tissue damage after injury and infection. Further studies will help translate the beneficial effects of this pathway into clinical use for our surgical patients.

Epicardial ganglionated plexus stimulation decreases postoperative inflammatory response in humans

BACKGROUND

Surgical cardiac revascularization produces a high degree of systemic inflammation and the secretion of several cytokines. Intensive postoperative inflammation may increase the incidence of postoperative atrial fibrillation and favor organ dysfunctions. No data documenting the anti-inflammatory properties of epicardial vagal ganglionated plexus stimulation are available.

OBJECTIVE

To verify the feasibility and safety of postoperative inferior vena cava-inferior atrial ganglionated plexus (IVC-IAGP) burst stimulation and the effectiveness of this approach in reducing serum levels of inflammatory cytokines.

METHODS

In 27 patients who were candidates for off-pump surgical revascularization, the IVC-IAGP was located during surgery, a temporary wire was inserted, and a negative atrioventricular node dromotropic effect was obtained in 20 patients on applying high-frequency burst stimulation. In 5 patients atrial fibrillation or phrenic nerve stimulation was induced, and the remaining 15 patients served as the experimental group. Twenty additional patients underwent off-pump surgical revascularization without IVC-IAGP stimulation and served as the control group. On arrival in the intensive care unit, the experimental group underwent IVC-IAGP stimulation for 6 hours. Blood samples were collected at different times.

RESULTS

The serum levels of cytokines were not statistically different at baseline and on arrival in the intensive care unit between the groups, while they proved statistically different after 6 hours of stimulation: interleukin-6 (EG: 121 ± 71 pg/mL vs CG: 280 ± 194 pg/mL; P = .004), tumor necrosis factor-α (EG: 2.68 ± 1.81 pg/mL vs CG: 5.87 ± 3.48 pg/mL; P = .003), vascular endothelial growth factor (EG: 93 ± 43 pg/mL vs CG: 177 ± 86 pg/mL; P = .002), and epidermal growth factor (EG: 79 ± 48 pg/mL vs CG: 138 ± 76 pg/mL; P = .012).

CONCLUSIONS

Prolonged burst IVC-IAGP stimulation after surgical revascularization appears to be feasible and safe and significantly reduces inflammatory cytokines in the postoperative period.

Activation of cholinergic anti-inflammatory pathway contributes to the protective effects of 100% oxygen inhalation on zymosan-induced generalized inflammation in mice

BACKGROUND

The 100% oxygen inhalation has been demonstrated to have a protective effect on mice with zymosan-induced generalized inflammation. However, the underlying mechanism is largely unknown. The present study was designed to explore the role of the cholinergic anti-inflammatory pathway in this animal model.

METHODS

Oxygen inhalation was given to mice at 4 and 12 h after zymosan injection. One group of mice underwent vagotomy 7 d before zymosan injection. The other two groups of mice either received nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine, or α7 nicotinic acetylcholine receptor (α7nAChR) antagonist methyllycaconitine 30 min before oxygen was given.

RESULTS

The 100% oxygen treatment significantly decreased the serum level of TNF-α and increased the serum level of IL-10. The pathologic changes of the heart, lung, liver, and kidney were attenuated, as well as the dysfunction of liver and kidney. The 7-d survival rate of zymosan-challenged mice was also improved. Conversely, all these protective effects caused by pure oxygen treatment were abolished in those animals that received anti-cholinergic treatments.

CONCLUSIONS

The cholinergic anti-inflammatory pathway may be involved in the 100% oxygen protective mechanism against zymosan-induced generalized inflammation in mice.

Anti-inflammatory effects of nicotine in obesity and ulcerative colitis

Cigarette smoke is a major risk factor for a number of diseases including lung cancer and respiratory infections. Paradoxically, it also contains nicotine, an anti-inflammatory alkaloid. There is increasing evidence that smokers have a lower incidence of some inflammatory diseases, including ulcerative colitis, and the protective effect involves the activation of a cholinergic anti-inflammatory pathway that requires the α7 nicotinic acetylcholine receptor (α7nAChR) on immune cells. Obesity is characterized by chronic low-grade inflammation, which contributes to insulin resistance. Nicotine significantly improves glucose homeostasis and insulin sensitivity in genetically obese and diet-induced obese mice, which is associated with suppressed adipose tissue inflammation. Inflammation that results in disruption of the epithelial barrier is a hallmark of inflammatory bowel disease, and nicotine is protective in ulcerative colitis. This article summarizes current evidence for the anti-inflammatory effects of nicotine in obesity and ulcerative colitis. Selective agonists for the α7nAChR could represent a promising pharmacological strategy for the treatment of inflammation in obesity and ulcerative colitis. Nevertheless, we should keep in mind that the anti-inflammatory effects of nicotine could be mediated via the expression of several nAChRs on a particular target cell.

Role of the cholinergic antiinflammatory pathway in murine autoimmune myocarditis

RATIONALE

This study was performed to gain insights into novel therapeutic approaches for the treatment of autoimmune myocarditis.

OBJECTIVE

Chemical stimulation of the efferent arm of the vagus nerve through activation of nicotinic acetylcholine receptor subtype-7α (α7-nAChR) has been shown to be protective in several models of inflammatory diseases. In the present study, we investigated the potentially protective effect of vagus nerve stimulation on myocarditis.

METHODS AND RESULTS

A/J mice were immunized with cardiac troponin I (TnI) to induce autoimmune myocarditis. Mice were exposed to drinking water that contained nicotine in different concentrations and for different time periods (for 3 days at 12.5 mg/L; 3 days at 125 mg/L; 21 days at 12.5 mg/L; and 21 days at 125 mg/L after first immunization). TnI-immunized mice with no pharmacological treatment showed extensive myocardial inflammation and fibrosis and significantly elevated levels of interleukin-6 and tumor necrosis factor-α. Furthermore, elevated levels of mRNA transcripts of proinflammatory chemokines (monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and RANTES) and chemokine receptors (CCR1, CCR2, and CCR5) were found. Oral nicotine administration reduced inflammation within the myocardium, decreased the production of interleukin-6 and tumor necrosis factor-α, and downregulated the expression of monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, RANTES, CCR1, CCR2, and CCR5. In addition, nicotine treatment resulted in decreased expression of matrix metalloproteinase-14, natriuretic peptide precursor B, tissue inhibitor of metalloproteinase-1, and osteopontin, proteins that are commonly involved in heart failure. Finally, we found that nicotine reduced levels of pSTAT3 (phosphorylated signal transducer and activator of transcription 3) protein expression within the myocardium. Neostigmine treatment did not affect the progression of myocarditis.

CONCLUSIONS

We showed that activation of the cholinergic antiinflammatory pathway with nicotine reduces inflammation in autoimmune myocarditis. Our results may open new possibilities in the therapeutic management of autoimmune myocarditis.

Electrical vagus nerve stimulation and nicotine effects in peritonitis-induced acute lung injury in rats

The cholinergic anti-inflammatory pathway has been identified as playing a key role in the communication between the central nervous system and the immune system during inflammation. The potential beneficial role of vagus nerve stimulation (VNS) remains to be clarified in established sepsis. We hypothesized that VNS or nicotine administration would reduce lung injury and mortality in established sepsis. We conducted a prospective, randomized experimental study. Four hours after peritonitis induction by cecal ligation and puncture (CLP), rats were randomized into three groups of seven animals according to the intervention: control group, VNS group (15 V, 2 ms, 5 Hz during 20 min), and nicotine group (400 µg/kg intraperitoneal). Survival was determined as lung injury score 4 and 8 h after CLP. Tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-10, cytokine-induced neutrophil chemoattractant (CINC)-3 and thrombin-antithrombin complexes (TATc) were measured at baseline and at 4 and 8 h after CLP. Survival at 8 h was 71.4%, 100%, and 23.8% in the control, VNS, and nicotine groups, respectively (p < 0.05). All animals had lung damage but without significant difference between groups even if nicotine-treated animals tended to have a higher score than the controls (p = 0.09). Neutrophil polymorphonuclear (PMN) infiltration was more pronounced in the nicotine group compared with the VNS group (p = 0.015) but not with the controls. TNF-α, IL-6, IL-10, CINC-3, and TATc were elevated in all groups (NS). In this model of established sepsis, posttreatment by VNS was associated with increased survival, while nicotine administration increased lung PMN infiltration and mortality. Nicotine-induced bacterial clearance impairment and nicotine systemic effects may explain these observations.

Molecular analysis of sepsis-induced changes in the liver: microarray study in a porcine model of acute fecal peritonitis with fluid resuscitation

Sepsis and septic shock are frequently encountered in the intensive care unit. Despite the evolution of intensive care medicine during the last decades, septic shock is still associated with high mortality and complications of sepsis such as cholestasis, liver dysfunction, and massive intravascular volume deficit. Little is known about the whole pattern of changes at the transcriptional level during the development of acute sepsis. Here we present a detailed molecular biological analysis of the events in the liver during the first day of acute bacterial infection in a clinically relevant model of porcine peritoneal sepsis. Before and 21 h after induction of sepsis by autologous fecal inoculum, liver samples were taken for microarray analysis. There were two groups of animals (7 control and 8 sepsis), two of each group where used in microarray, the remaining were used for confirmation of selected genes by real-time polymerase chain reaction. Pathway analysis revealed that in acute sepsis, gene expression was significantly changed in processes related to apoptosis, inflammation, and oxidant/redox balance. Although after 21 h these animals are expected to die within the next 3 to 4 h from massive complications, functional induction of apoptosis could not be confirmed. Computer analysis identified three key regulator genes (IL8, CCL2, and CXCL2) among the first genes to be upregulated specifically in the sepsis group, and these can directly or indirectly control the bulk of the sepsis response. Induction of inflammatory mediators by sepsis was supported by the detection of corresponding cytokines (interleukin 6 and interleukin 8) in the blood.

Interplay between inflammation, immune system and neuronal pathways: Effect on gastrointestinal motility

Sepsis is a systemic inflammatory response representing the leading cause of death in critically ill patients, mostly due to multiple organ failure. The gastrointestinal tract plays a pivotal role in the pathogenesis of sepsis-induced multiple organ failure through intestinal barrier dysfunction, bacterial translocation and ileus. In this review we address the role of the gastrointestinal tract, the mediators, cell types and transduction pathways involved, based on experimental data obtained from models of inflammation-induced ileus and (preliminary) clinical data. The complex interplay within the gastrointestinal wall between mast cells, residential macrophages and glial cells on the one hand, and neurons and smooth muscle cells on the other hand, involves intracellular signaling pathways, Toll-like receptors and a plethora of neuroactive substances such as nitric oxide, prostaglandins, cytokines, chemokines, growth factors, tryptases and hormones. Multidirectional signaling between the different components in the gastrointestinal wall, the spinal cord and central nervous system impacts inflammation and its consequences. We propose that novel therapeutic strategies should target inflammation on the one hand and gastrointestinal motility, gastrointestinal sensitivity and even pain signaling on the other hand, for instance by impeding afferent neuronal signaling, by activation of the vagal anti-inflammatory pathway or by the use of pharmacological agents such as ghrelin and ghrelin agonists or drugs interfering with the endocannabinoid system.

Genomic polymorphisms within alpha 7 nicotinic acetylcholine receptor and severe sepsis in Chinese Han population

Alpha 7 nicotinic acetylcholine receptor, a kind of ligand-gated ion channel mainly expressed in macrophages, plays a crucial role in improving survival in sepsis via suppressing proinflammatory cytokines. The predisposition of genomic polymorphisms within alpha 7 nicotinic acetylcholine receptor gene (CHRNA7) to sepsis has not been investigated. The current association study was performed to analyse six common genetic variations within 5'-upstream region of CHRNA7 gene in 229 patients with severe sepsis and 267 controls. Neither allelic frequencies nor genotype distributions were significantly different between patients and controls, as well as between surviving and nonsurviving patients. The frequencies of estimated haplotypes were also comparable between above defined groups. The present study suggests that genomic polymorphisms in the 5'-upstream region of CHRNA7 gene may not be a major risk factor for severe sepsis in Chinese Han population.

15-deoxy-delta 12,14-prostaglandin J2 prevents inflammatory response and endothelial cell damage in rats with acute obstructive cholangitis

Acute obstructive cholangitis is a common disease with a high mortality rate. Ligands for peroxisome proliferator-activated receptor-gamma (PPARgamma), such as 15-deoxy-Delta(12,14)-prostaglandin J(2) (15D-PGJ(2)), have been proposed as a new class of anti-inflammatory compounds. This study investigated the effect of 15D-PGJ(2) treatment on lipopolysaccharide (LPS)-induced acute obstructive cholangitis. The rats were randomly assigned to five groups: sham operation (Sham; simple laparotomy), sham operation with intraperitoneal saline infusion (Sham+Saline), sham operation with intraperitoneal LPS infusion (Sham+LPS), bile duct ligation (BDL) with saline infusion into the bile duct (BDL+Saline), and BDL with LPS infusion into the bile duct (BDL+LPS). Biochemical assays of blood samples, histology of the liver, portal venous pressure, hyaluronic acid clearance, and expression of inflammation-associated genes in the liver were evaluated. Furthermore, the Sham+LPS and the BDL+LPS group were divided into two groups (with and without 15D-PGJ(2) treatment), and their survival rates were compared. Biochemical assays of blood samples, portal venous pressure, hyaluronic acid clearance, and expression of inflammation-associated genes in the liver were all significantly higher in the BDL+LPS group compared with those in the BDL+Saline group, indicating the presence of increased liver damage in the first group. However, preoperative administration of 15D-PGJ(2) significantly improved these outcomes. Furthermore, the survival rate after establishment of cholangitis was significantly improved by the administration of 15D-PGJ(2) in the BDL+LPS group. These results clearly demonstrate that 15D-PGJ(2) inhibits the inflammatory response and endothelial cell damage seen in acute obstructive cholangitis and could contribute to improve the outcome of this pathology.

The vagus nerve and nicotinic receptors involve inhibition of HMGB1 release and early pro-inflammatory cytokines function in collagen-induced arthritis

OBJECTIVES

The cholinergic anti-inflammatory pathway, a vagus nerve-dependent mechanism, inhibits cytokine releases in models of acute inflammatory disease. We investigated the efficacy and elucidated the possible mechanism of the cholinergic anti-inflammatory pathway on collagen-induced arthritis (CIA) in mice.

METHODS

Fifty-six male DBA/1 mice were divided into four groups: control mice (sham vagotomy + phosphate-buffered saline; shamVGX+PBS), model mice (shamVGX+PBS+CIA), vagotomy mice (VGX+PBS+CIA), and nicotine (Nic) mice (shamVGX+Nic+CIA). We subjected mice to left-side cervical vagotomy 4 days before induction of arthritis. Mice in the nicotine group were injected with nicotine (250 microg/kg per day) 4 days before arthritis induction. Arthritis score was measured and histopathologic assessment of joint sections carried out. The concentration of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-10 in serum were evaluated by ELISA. Expression of high-mobility group box chromosomal protein 1(HMGB1) was evaluated by immunohistochemical staining of joints.

RESULTS

Vagotomy exaggerated, whereas nicotine attenuated, clinical arthritis. Histopathologic findings confirmed that nicotine reduced infiltration of inflammatory cell and bone destruction. Expression of TNF-alpha and IL-6 decreased in nicotine-pretreated mice compared with model and vagotomy mice; IL-10 levels were not significantly different between the model group and nicotine group. Nicotine reduced the expression and translocation of HMGB1 in the inflamed joints of CIA mice.

CONCLUSIONS

The cholinergic anti-inflammatory pathway has an anti-inflammatory role in the pathophysiology of rheumatoid arthritis (RA) via inhibiting HMGB1 release and early pro-inflammatory cytokines function. Study of this pathway could be used for RA therapy.

Loss of vagal anti-inflammatory effect: in vivo visualization and adoptive transfer

The vagus nerve is a conduit for bidirectional signaling between the brain and the viscera. Vagal signaling has been shown to downregulate gastrointestinal inflammation, and the mechanism is thought to involve acetylcholine binding to the alpha-7 subunit of the nicotinic acetylcholine receptor on macrophages. The aims of this study were to quantify the impact of vagotomy in vivo by visualizing nuclear factor (NF)-kappaB activity and to determine if the proinflammatory impact of vagotomy could be transferred by lymphocytes. Real-time biophotonic imaging revealed that subdiaphragmatic vagotomy resulted in increased levels of NF-kappaB in vivo. NF-kappaB activation was further exaggerated in vivo following exposure to 4% DSS for 5 days. Vagotomized animals also exhibited higher disease activity scores and secreted more proinflammatory cytokines. Adoptive transfer of CD4(+) T cells from vagotomized animals (but not CD4(+) T cells from sham-operated controls) to naive dextran sulfate sodium (DSS)-treated recipients resulted in increased inflammatory scores. Further examination of the CD4(+) T cells revealed that adoptive transfer of the CD25(-) population alone from vagotomized donors (but not sham-operated donors) was sufficient to aggravate colitis in DSS-treated recipients. Increased DSS-induced inflammation was associated with reduced CD4(+)CD25(+)Foxp3(+) regulatory T cell numbers in recipients. This study clearly demonstrates the ability of the vagus nerve to modulate activity of the proinflammatory transcription factor NF-kappaB in vivo. The proinflammatory effect of vagotomy is transferable using splenic T cells and highlights a previously unappreciated cellular mechanism for linking central parasympathetic processes with mucosal inflammation and immune homeostasis.

Cholinergic control of inflammation

Cytokine production is necessary to protect against pathogens and promote tissue repair, but excessive cytokine release can lead to systemic inflammation, organ failure and death. Inflammatory responses are finely regulated to effectively guard from noxious stimuli. The central nervous system interacts dynamically with the immune system to modulate inflammation through humoral and neural pathways. The effect of glucocorticoids and other humoral mediators on inflammatory responses has been studied extensively in the past decades. In contrast, neural control of inflammation has only been recently described. We summarize autonomic regulation of local and systemic inflammation through the 'cholinergic anti-inflammatory pathway', a mechanism consisting of the vagus nerve and its major neurotransmitter, acetylcholine, a process dependent on the nicotinic acetylcholine receptor alpha7 subunit. We recapitulate additional sources of acetylcholine and their contribution to the inflammatory response, as well as acetylcholine regulation by acetylcholinesterase as a means to attenuate inflammation. We discuss potential therapeutic applications to treat diseases characterized by acute or chronic inflammation, including autoimmune diseases, and propose future research directions.