Unphosphorylated STAT3 modulates alpha 7 nicotinic receptor signaling and cytokine production in sepsis

B cells modulate lung antiviral inflammatory responses via the neurotransmitter acetylcholine

The rapid onset of innate immune defenses is critical for early control of viral replication in an infected host, yet it can also lead to irreversible tissue damage, especially in the respiratory tract. Intricate regulatory mechanisms must exist that modulate inflammation, while controlling the infection. Here, B cells expressing choline acetyl transferase (ChAT), an enzyme required for production of the metabolite and neurotransmitter acetylcholine (ACh) are identified as such regulators of the immediate early response to influenza A virus. Lung tissue ChAT + B cells are shown to interact with a7 nicotinic Ach receptor-expressing lung interstitial macrophages in mice within 24h of infection to control their production of TNFa, shifting the balance towards reduced inflammation at the cost of enhanced viral replication. Thus, innate-stimulated B cells are key participants of an immediate-early regulatory cascade that controls lung tissue damage after viral infection.

IL-1β, the first piece to the puzzle of sepsis-related cognitive impairment?

Sepsis is a leading cause of death resulting from an uncontrolled inflammatory response to an infectious agent. Multiple organ injuries, including brain injuries, are common in sepsis. The underlying mechanism of sepsis-associated encephalopathy (SAE), which is associated with neuroinflammation, is not yet fully understood. Recent studies suggest that the release of interleukin-1β (IL-1β) following activation of microglial cells plays a crucial role in the development of long-lasting neuroinflammation after the initial sepsis episode. This review provides a comprehensive analysis of the recent literature on the molecular signaling pathways involved in microglial cell activation and interleukin-1β release. It also explores the physiological and pathophysiological role of IL-1β in cognitive function, with a particular focus on its contribution to long-lasting neuroinflammation after sepsis. The findings from this review may assist healthcare providers in developing novel interventions against SAE.

Malat1 regulates PMN-MDSC expansion and immunosuppression through p-STAT3 ubiquitination in sepsis

Myeloid-derived suppressor cells (MDSCs) expand during sepsis and contribute to the development of persistent inflammation-immunosuppression-catabolism syndrome. However, the underlying mechanism remains unclear. Exploring the mechanisms of MDSCs generation may provide therapeutic targets for improving immune status in sepsis. Here, a sepsis mouse model is established by cecal ligation and perforation. Bone marrow cells at different sepsis time points are harvested to detect the proportion of MDSCs and search for differentially expressed genes by RNA-sequence. In lethal models of sepsis, polymorphonuclear-MDSCs (PMN-MDSCs) decrease in early but increase and become activated in late sepsis, which is contrary to the expression of metastasis-associated lung adenocarcinoma transcript 1 (Malat1). In vivo, Malat1 inhibitor significantly increases the mortality in mice with late sepsis. And in vitro, Malat1 down-regulation increases the proportion of PMN-MDSCs and enhanced its immunosuppressive ability. Mechanistically, Malat1 limits the differentiation of PMN-MDSCs by accelerating the degradation of phosphorylated STAT3. Furthermore, Stattic, an inhibitor of STAT3 phosphorylation, improves the survival of septic mice by inhibiting PMN-MDSCs. Overall, the study identifies a novel insight into the mechanism of sepsis-induced MDSCs and provides more evidence for targeting MDSCs in the treatment of sepsis.

(E)-2-methoxy-4-(3-(4-methoxyphenyl)prop-1-en-1-yl)phenol alleviates inflammatory responses in LPS-induced mice liver sepsis through inhibition of STAT3 phosphorylation

Sepsis is a life-threatening disease with limited treatment options, and the inflammatory process represents an important factor affecting its progression. Many studies have demonstrated the critical roles of signal transducer and activator of transcription 3 (STAT3) in sepsis pathophysiology and pro-inflammatory responses. Inhibition of STAT3 activity may therefore represent a promising treatment option for sepsis. We here used a mouse model to demonstrate that (E)-2-methoxy-4-(3-(4-methoxyphenyl)prop-1-en-1-yl)phenol (MMPP) treatment prevented the liver sepsis-related mortality induced by 30 mg/kg lipopolysaccharide (LPS) treatment and reduced LPS-induced increase in alanine transaminase, aspartate transaminase, and lactate dehydrogenase levels, all of which are markers of liver sepsis progression. These recovery effects were associated with decreased LPS-induced STAT3, p65, and JAK1 phosphorylation and proinflammatory cytokine (interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha) level; expression of cyclooxygenase-2 and induced nitric oxide synthase were also reduced by MMPP. In an in vitro study using the normal liver cell line THLE-2, MMPP treatment prevented the LPS-induced increase of STAT3, p65, and JAK1 phosphorylation and inflammatory protein expression in a dose-dependent manner, and this effect was enhanced by combination treatment with MMPP and STAT3 inhibitor. The results clearly indicate that MMPP treatment prevents LPS-induced mortality by inhibiting the inflammatory response via STAT3 activity inhibition. Thus, MMPP represents a novel agent for alleviating LPS-induced liver sepsis.

Deficiency of S100A8/A9 attenuates pulmonary microvascular leakage in septic mice

BACKGROUND

We have reported a positive correlation between S100 calcium-binding protein (S100) A8/S100A9 and sepsis-induced lung damage before. However, limited knowledge exists concerning the biological role of S100A8/A9 in pulmonary vascular endothelial barrier dysfunction, as well as the diagnostic value of S100A8/A9 in sepsis.

METHODS

Sepsis was induced in C57BL/6J mice and S100A9-knockout (KO) mice through the cecal ligation and puncture (CLP). Pulmonary vascular leakage was determined by measuring extravasated Evans blue (EB). Reverse transcription polymerase chain reaction and the histological score were used to evaluate inflammation and lung injury, respectively. Recombinant S100A8/A9 (rhS100A8/A9) was used to identify the effects of S100A8/A9 on endothelial barrier dysfunction in human umbilical vein endothelial cells (HUVECs). Additionally, the diagnostic value of S100A8/A9 in sepsis was assessed using receiver operating characteristic.

RESULTS

S100A8/A9 expression was up-regulated in the lungs of CLP-operated mice. S100A9 KO significantly reversed CLP-induced hypothermia and hypotension, resulting in an improved survival rate. S100A9 KO also decreased the inflammatory response, EB leakage, and histological scores in the lungs of CLP-operated mice. Occludin and VE-cadherin expressions were decreased in the lungs of CLP-operated mice; However, S100A9 KO attenuated this decrease. Moreover, CLP-induced signal transducer and activator of transcription 3 (STAT3) and p38/extracellular signal-regulated kinase (ERK) signalling activation and apoptosis were mitigated by S100A9 KO in lungs. In addition, rhS100A8/A9 administration significantly decreased occludin and VE-cadherin expressions, increased the phosphorylated (p)-ERK/ERK, p-p38/p38, and B-cell leukaemia/lymphoma 2 protein (Bcl-2)-associated X protein/Bcl-2 ratios in HUVECs.

CONCLUSION

The present study demonstrated S100A8/A9 aggravated sepsis-induced pulmonary inflammation, vascular permeability, and lung injury. This was achieved, at least partially, by activating the P38/STAT3/ERK signalling pathways. Moreover, S100A8/A9 showed the potential as a biomarker for sepsis diagnosis.

Stattic ameliorates the cecal ligation and puncture-induced cardiac injury in septic mice via IL-6-gp130-STAT3 signaling pathway

AIM

Sepsis-induced cardiac dysfunction is the leading cause of higher morbidity and mortality with poor prognosis in septic patients. Our recent previous investigation provides evidence of the hallmarks of signal transducer and activator of transcription3 (STAT3) activation in sepsis and targeting of STAT3 with Stattic, a small-molecule inhibitor of STAT3, has beneficial effects in various septic tissues. We investigated the possible cardioprotective effects of Stattic on cardiac inflammation and dysfunction in mice with cecal ligation and puncture (CLP)-induced sepsis.

MAIN METHODS

A polymicrobial sepsis model was induced by CLP in mice and Stattic (25 mg/kg) was intraperitoneally given at one and twelve hours after CLP operation. The cecum was exposed in sham-control mice without CLP. After 18 h of surgery, electrocardiogram (ECG) for anaesthized mice was registered followed by collecting of samples of blood and tissues for bimolecular and histopathological assessments. Myeloperoxidase, a marker of neutrophil infiltration, was assessed immunohistochemically.

KEY FINDINGS

CLP profoundly impaired cardiac functions as evidenced by ECG changes in septic mice as well as elevation of cardiac enzymes, and inflammatory markers with myocardial histopathological and immunohistochemical alterations. While, Stattic markedly reversed the CLP-induced cardiac abnormalities and restored the cardiac function by its anti-inflammatory activities.

SIGNIFICANCE

Stattic treatment had potential beneficial effects against sepsis-induced cardiac inflammation, dysfunction and damage. Its cardioprotective effects were possibly attributed to its anti-inflammatory activities by targeting STAT3 and downregulation of IL-6 and gp130. Our investigations suggest that Stattic could be a promising target for management of cardiac sepsis and inflammation-related cardiac damage.

Signaling of nicotinic acetylcholine receptors in mononuclear phagocytes

Nicotinic acetylcholine receptors are not only expressed by the nervous system and at the neuro-muscular junction but also by mononuclear phagocytes, which belong to the innate immune system. Mononuclear phagocyte is an umbrella term for monocytes, macrophages, and dendritic cells. These cells play pivotal roles in host defense against infection but also in numerous often debilitating diseases that are characterized by exuberant inflammation. Nicotinic acetylcholine receptors of the neuronal type dominate in these cells, and their stimulation is mainly associated with anti-inflammatory effects. Although the cholinergic modulation of mononuclear phagocytes is of eminent clinical relevance for the prevention and treatment of inflammatory diseases and neuropathic pain, we are only beginning to understand the underlying mechanisms on the molecular level. The purpose of this review is to report and critically discuss the current knowledge on signal transduction mechanisms elicited by nicotinic acetylcholine receptors in mononuclear phagocytes.

Spinal Cord Stimulation Attenuates Neural Remodeling, Inflammation, and Fibrosis After Myocardial Infarction

OBJECTIVES

Spinal cord stimulation (SCS) is an established neuromodulation method that regulates the cardiac autonomic system. However, the biological mechanisms of the therapeutic effects of SCS after myocardial infarction (MI) remain unclear.

MATERIALS AND METHODS

Twenty-five rabbits were divided into five groups: SCS-MI (voltage: 0.5 v; pulse width: 0.2 ms; 50 Hz; ten minutes on and 30 minutes off; two weeks; n = 5), MI (n = 5), sham SCS-MI (voltage: 0 v; two weeks; n = 5), sham MI (n = 5), and blank control (n = 5) groups. MI was induced by permanent left anterior descending artery ligation. SCS-MI and sham SCS-MI rabbits received the corresponding interventions 24 hours after MI. Autonomic remodeling was evaluated using enzyme-linked immunosorbent assay and immunohistochemistry. Inflammation and myocardial fibrosis were assessed using immunohistochemistry, quantitative polymerase chain reaction, hematoxylin and eosin staining, Masson staining, and Western blot.

RESULTS

SCS improved the abnormal systemic autonomic activity. Cardiac norepinephrine decreased after MI (p < 0.01) and did not improve with SCS. Cardiac acetylcholine increased with SCS compared with the MI group (p < 0.05). However, no difference was observed between the MI and blank control groups. Growth-associated protein 43 (p < 0.001) and tyrosine hydroxylase (p < 0.001) increased whereas choline acetyltransferase (p < 0.05) decreased in the MI group compared with the blank control group. These changes were attenuated with SCS. SCS inhibited inflammation, decreased the ratio of phosphorylated-Erk to Erk (p < 0.001), and increased the ratio of phosphorylated-STAT3 to STAT3 (p < 0.001) compared with the MI group. Myocardial fibrosis was also attenuated by SCS.

CONCLUSIONS

SCS improved abnormal autonomic activity after MI, leading to reduced inflammation, reactivation of STAT3, and inhibition of Erk. Additionally, SCS attenuated myocardial fibrosis. Our results warrant future studies of biological mechanisms of the therapeutic effects of SCS after MI.

Neural control of the spleen as an effector of immune responses to inflammation: mechanisms and treatments

Immune system responses are a vital defense mechanism against pathogens. Inflammatory mediators finely regulate complex inflammatory responses from initiation to resolution. However, in certain conditions, the inflammation is initiated and amplified, but not resolved. Understanding the biological mechanisms underlying the regulation of the immune response is critical for developing therapeutic alternatives, including pharmaceuticals and bioelectronic tools. The spleen is an important immune effector organ since it orchestrates innate and adaptive immune responses such as pathogen clearance, cytokine production, and differentiation of cells, therefore playing a modulatory role that balances pro- and anti-inflammatory responses. However, modulation of splenic immune activity is a largely unexplored potential therapeutic tool that could be used for the treatment of inflammatory and life-threatening conditions. This review discusses some of the mechanisms controlling neuroimmune communication and the brain-spleen axis.

Cerebellar fastigial nucleus electrostimulation attenuates inflammation in a Post-Infarction rat model by activating cholinergic anti-inflammatory pathways

There are negative correlations between indices of heart rate variability (HRV) and markers of inflammation. The inflammation plays an important role in myocardial damages after myocardial infarction (MI). Our previous study found that fastigial nucleus electrostimulation (FNS) improved abnormal HRV in a rat model of MI. Whether and how it can reduce inflammation and improve cardiac function after MI and the underlying mechanisms remain unknown. 66 Sprague Dawley rats were randomly divided into 4 groups as follows: i) Sham operation group (Sham); ii) Myocardial infarction group (MI); iii) FNS+MI group (FNS plus MI): left fastigial nucleus electrostimulation; iv) FNL+FNS+MI group (left fastigial nucleus lesion plus FNS plus MI). The serum expressions of acetylcholine (ACh), pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and anti-inflammatory cytokines IL-10 after FNS were measured using ELISA. Subsequently, the infarct size, the infiltration of inflammatory cells, the fibrotic area, and cardiac function were also evaluated. Additionally, the effects of FNS on the cholinergic anti-inflammatory pathway (CAP)-related proteins expression were determined by Western blot. We found that FNS significantly upregulated ACh and IL-10 expressions in serum, and decreased TNF-α and IL-6 levels. FNS significantly attenuated inflammatory cell infiltration and infarct size, decreased fibrosis, increased left ventricular ejection fraction (LVEF), and reduced mortality. Besides, the levels of p-STAT3/STAT3 and p-NF-κB/NF-κB significantly elevated after MI. FNS down-regulated the expression of p-STAT3/STAT3 and p-NF-κB/NF-κB. The protective effects of FNS were partially reversed by the fastigial nucleus lesion. Our data suggested that FNS can alleviate the inflammation after MI, and its cardiac neuroprotective mechanism may be achieved by increasing vagus tone, releasing ACh, and further activating the CAP via α7nAChR. The precise mechanism remains to be elucidated.

Activation of Cholinergic Anti-Inflammatory Pathway Ameliorates Cerebral and Cardiac Dysfunction After Intracerebral Hemorrhage Through Autophagy

Background

Intracerebral hemorrhage (ICH) is the devastating subtype of stroke with cardiovascular complications, resulting in high rates of mortality and morbidity with the release of inflammatory factors. Previous studies have demonstrated that activation of α7nAChR can reduce immune and inflammation-related diseases by triggering the cholinergic anti-inflammatory pathway (CAIP). α7nAChR mediates protection from nervous system inflammation through AMPK-mTOR-p70S6K-associated autophagy. Therefore, the purpose of this study is to explore whether the activation of α7nAChR improves cerebral and cardiac dysfunction after ICH through autophagy.

Methods

Male C57BL/6 mice were randomly divided into five groups (1): Control + saline (2), ICH+ saline (3), ICH + PNU-282987 (4), ICH+ PNU-282987 + MLA (5), ICH + PNU-282987 + 3-MA. The neurological function was evaluated at multiple time points. Brain water content was measured at 3 days after ICH to assess the severity of brain edema. PCR, immunofluorescence staining, and Western Blot were performed at 7 days after ICH to detect inflammation and autophagy. Picro-Sirius Red staining was measured at 30 days after ICH to evaluate myocardial fibrosis, echocardiography was performed at 3 and 30 days to measure cardiac function.

Results

Our results indicated that the PNU-282987 reduced inflammatory factors (MCP-1, IL-1β, MMP-9, TNF-α, HMGB1, TLR2), promoted the polarization of macrophage/microglia into anti-inflammatory subtypes(CD206), repaired blood-brain barrier injury (ZO-1, Claudin-5, Occludin), alleviated acute brain edema and then recovered neurological dysfunction. Echocardiography and PSR indicated that activation of α7nAChR ameliorated cardiac dysfunction. Western Blot showed that activation of α7nAChR increased autophagy protein (LC3, Beclin) and decreased P62. It demonstrated that the activation of α7nAChR promotes autophagy and then recovers brain and heart function after ICH.

Conclusions

In conclusion, PNU-282987 promoted the cerebral and cardiac functional outcomes after ICH in mice through activated α7nAChR, which may be attributable to promoting autophagy and then reducing inflammatory reactions after ICH.

The α7 nAChR allosteric modulator PNU-120596 amends neuroinflammatory and motor consequences of parkinsonism in rats: Role of JAK2/NF-κB/GSk3β/ TNF-α pathway

Parkinson's disease (PD) is the second most common neurodegenerative disorder and a leading cause of disability. The current gold standard for PD treatment, L-Dopa, has limited clinical efficacy and multiple side effects. Evidence suggests that activation of α7 nicotinic acetylcholine receptors (α7nAChRs) abrogates neuronal and inflammatory insults. Here we tested whether PNU-120596 (PNU), a type II positive allosteric modulator of α7 nAChR, has a critical role in regulating motor dysfunction and neuroinflammation correlated with the associated PD dysfunction. Neuroprotective mechanisms were investigated through neurobehavioral, molecular, histopathological, and immunohistochemical studies. PNU reversed motor incoordination and hypokinesia induced via the intrastriatal injection of 6-hydroxydopamine and manifested by lower falling latency in the rotarod test, short ambulation time and low rearing incidence in open field test. Tyrosine hydroxylase immunostaining showed a significant restoration of dopaminergic neurons following PNU treatment, in addition to histopathological restoration in nigrostriatal tissues. PNU halted striatal neuroinflammation manifested as a suppressed expression of JAK2/NF-κB/GSk3β accompanied by a parallel decline in the protein expression of TNF-α in nigrostriatal tissue denoting the modulator anti-inflammatory capacity. Moreover, the protective effects of PNU were partially reversed by the α7 nAChR antagonist, methyllycaconitine, indicating the role of α7 nAChR modulation in the mechanism of action of PNU. This is the first study to reveal the positive effects of PNU-120596 on motor derangements of PD via JAK2/NF-κB/GSk3β/ TNF-α neuroinflammatory pathways, which could offer a potential therapeutic strategy for PD.

Polymorphisms in alpha 7 nicotinic acetylcholine receptor gene, CHRNA7, and its partially duplicated gene, CHRFAM7A, associate with increased inflammatory response in human peripheral mononuclear cells

The vagus nerve can, via the alpha 7 nicotinic acetylcholine receptor (α7nAChR), regulate inflammation. The gene coding for the α7nAChR, CHRNA7, can be partially duplicated, that is, CHRFAM7A, which is reported to impair the anti-inflammatory effect mediated via the α7nAChR. Several single nucleotide polymorphisms (SNPs) have been described in both CHRNA7 and CHRFAM7A, however, the functional role of these SNPs for immune responses remains to be investigated. In the current study, we set out to investigate whether genetic variants of CHRNA7 and CHRFAM7A can influence immune responses. By investigating data available from the Swedish SciLifeLab SCAPIS Wellness Profiling (S3WP) study, in combination with droplet digital PCR and freshly isolated PBMCs from the S3WP participants, challenged with lipopolysaccharide (LPS), we show that CHRNA7 and CHRFAM7A are expressed in human PBMCs, with approximately four times higher expression of CHRFAM7A compared with CHRNA7. One SNP in CHRFAM7A, rs34007223, is positively associated with hsCRP in healthy individuals. Furthermore, gene ontology (GO)-terms analysis of plasma proteins associated with gene expression of CHRNA7 and CHRFAM7A demonstrated an involvement for these genes in immune responses. This was further supported by in vitro data showing that several SNPs in both CHRNA7 and CHRFAM7A are significantly associated with cytokine response. In conclusion, genetic variants of CHRNA7 and CHRFAM7A alters cytokine responses. Furthermore, given that CHRFAM7A SNP rs34007223 is associated with inflammatory marker hsCRP in healthy individuals suggests that CHRFAM7A may have a more pronounced role in regulating inflammatory processes in humans than previously been recognized.

α7 Nicotinic Acetylcholine Receptor Agonists Regulate Inflammation and Growth Hormone Resistance in Sepsis

ABSTRACT

During sepsis the normal induction of circulating insulin-like growth factor-I (IGF-I) by growth hormone (GH) action on liver is attenuated, a phenomenon called hepatic GH resistance. Hepatic GH resistance can be caused by cytokine-mediated activation of the NF-κB pathway which interferes with normal GH-signaling. The afferent and efferent fibers of the vagus nerve are integral to the cholinergic anti-inflammatory pathway (CAP) which attenuates hepatic TNFα production by activating the α7 nicotinic acetylcholine receptor (α7nAChR). We examined the effects of selective afferent vagotomy (SAV) and α7nAChR activation on sepsis-induced mortality, hepatic and systemic inflammation, the GH/IGF system and hepatic GH resistance using Sprague Dawley (SD) rats, C57BL/6 wild type (WT) mice, and α7nAChR knockout (KO) mice. Capsaicin was used to perform SAV and GTS-21 (α7nAChR agonist) was used to activate the α7nAChR. Sepsis-induced mortality, hepatic NF-κB activation, and plasma cytokine levels were increased in SAV rats and reduced in GTS-21-treated mice. The effects of sepsis on the GH/IGF-I system plasma IGF-I, IGF binding protein-1 (IGFBP-1), hepatic IGF-I, IGFBP-1, and GH receptor (GHR) mRNA and rhGH-responsiveness in mice were improved by GTS-21. Collectively these results confirm the protective effects of the anti-inflammatory CAP and α7nAChR activation in sepsis. They also provide evidence the CAP and α7nAChR activation could be used to attenuate hepatic GH resistance and anabolic failure in sepsis.

Esculetin protects against early sepsis via attenuating inflammation by inhibiting NF-κB and STAT1/STAT3 signaling

Esculetin, a natural derivative from the traditional and widely-used Chinese medicinal herb Cortex Fraxini, has a variety of pharmacological effects, especially in anti-inflammation. However, it is not clear whether esculetin has a therapeutic effect on sepsis. This study aimed to investigate the anti-inflammatory and protective effects of esculetin on early sepsis. The results showed that the lung injury was significantly relieved with the treatment of esculetin, accompanied with the restrained production of inflammatory factors including IL-1β, IL-6, TNF-α, CCL2 and iNOS during the early phase of E.coli-induced sepsis. Of note, activation of NF-κB and STAT1/STAT3 signals, the main upstream signals of many inflammatory factors, were attenuated by esculetin in both lung tissues from septic mice and LPS-stimulated macrophage. These findings suggested that the protection of esculetin against early sepsis should be related to its anti-inflammatory effect, which was at least partly due to its inhibition on NF-κB and STAT1/STAT3 signaling pathway in macrophage. Thus, esculetin could serve as a potential therapeutic agent by rebalancing innate immune response in macrophage for the treatment of early sepsis.

Targeting STAT3: A crucial modulator of sepsis

Signal transducer and activator of transcription 3 (STAT3) is a cellular signal transcription factor that has recently attracted a great deal of attention. It can trigger a variety of genes transcription in response to cytokines and growth factors stimulation, which plays an important role in many cellular biological processes involved in anti/proinflammatory responses. Sepsis is a life-threatening organ dysfunction resulting from dysregulated host responses to infection. As a converging point of multiple inflammatory responses pathways, accumulating studies have presented the elaborate network of STAT3 in sepsis pathophysiology; these results generally indicate a promising therapeutic application for targeting STAT3 in the treatment of sepsis. In the present review, we evaluated the published literature describing the use of STAT3 in the treatment of experimental and clinical sepsis. The information presented here may be useful for the design of future studies and may highlight the potential of STAT3 as a future biomarker and therapeutic target for sepsis.

Cholinergic Modulation of the Immune System in Neuroinflammatory Diseases

Frequent diseases of the CNS, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and psychiatric disorders (e.g., schizophrenia), elicit a neuroinflammatory response that contributes to the neurodegenerative disease process itself. The immune and nervous systems use the same mediators, receptors, and cells to regulate the immune and nervous systems as well as neuro-immune interactions. In various neurodegenerative diseases, peripheral inflammatory mediators and infiltrating immune cells from the periphery cause exacerbation to current injury in the brain. Acetylcholine (ACh) plays a crucial role in the peripheral and central nervous systems, in fact, other than cells of the CNS, the peripheral immune cells also possess a cholinergic system. The findings on peripheral cholinergic signaling, and the activation of the “cholinergic anti-inflammatory pathway” mediated by ACh binding to α7 nAChR as one of the possible mechanisms for controlling inflammation, have restarted interest in cholinergic-mediated pathological processes and in the new potential therapeutic target for neuro-inflammatory-degenerative diseases. Herein, we focus on recent progress in the modulatory mechanisms of the cholinergic anti-inflammatory pathway in neuroinflammatory diseases.

Electroacupuncture ameliorates intestinal inflammation by activating α7nAChR-mediated JAK2/STAT3 signaling pathway in postoperative ileus

Inflammatory cytokines produced by muscularis macrophages largely contribute to the pathological signs of postoperative ileus (POI). Electroacupuncture (EA) can suppress inflammation, mainly or partly via activation of vagal efferent. The goal of this study was to investigate the mechanisms by which EA stimulation at an hindlimb region ameliorates inflammation in POI.

Methods: Intestinal motility and inflammation were examined after 24 h after intestinal manipulation (IM)-induced POI in mice. Local immune response in the intestinal muscularis, expression of macrophages, α7 nicotinic acetylcholine receptor (α7nAChR), Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) were determined by flow cytometry, Western Blot, qPCR and immunofluorescence. The effects of α7nAChR antagonists (methyllycaconitine and α-bungarotoxin) and JAK2/STAT3 inhibitors (AG490 and WP1066) were also administered in a subset of mice prior to EA. In the parasympathetic pathways, intestinal motility and inflammation were determined after cervical vagotomy and sub-diaphragmatic vagotomy. The expression of gamma absorptiometry aminobutyric acid (GABA_A) receptor in dorsal motor nucleus of vagal (DMV) cholinergic neurons was assessed by immunofluorescence and the response to DMV microinjection of bicuculine (antagonist of GABA_A receptor) or muscimol (agonist of GABA_A receptor) were assessed.

Results: EA suppressed intestinal inflammation and promoted gastrointestinal motility. Mechanistically, EA activated the α7nAChR-mediated JAK2/STAT3 signaling pathway in macrophages which reduced the production of inflammatory cytokines. Furthermore, we also demonstrated that hindlimb region stimulation drove vagal efferent output by inhibiting the expression of GABA_A receptor in DMV to ameliorate inflammation.

Conclusions: The present study revealed that EA of hindlimb regions inhibited the expression of GABA_A receptor in DMV neurons, whose excited vagal nerve, in turn suppressed IM-induced inflammation via activation of α7nAChR-mediated JAK2/STAT3 signaling pathway.

Tropisetron balances immune responses via TLR2, TLR4 and JAK2/STAT3 signalling pathway in LPS-stimulated PBMCs

Numerous documents have been stated that tropisetron, an antagonist of the 5-HT3 receptor and α7nAChR agonist, modulates immune responses. However, the mechanistic basis for this aspect of tropisetron action is largely unknown. Here, the immuno-modulatory effects of tropisetron are investigated, focusing on the possible molecular targets and the mechanisms. Aside from the well-characterized role in immune signalling, JAK2/STAT3, TLR2 and TLR4 are signal transducers linked to both immuno-modulatory actions of acetylcholine and serotonin. Therefore, we evaluated their involvement in the immunoregulatory effects of tropisetron. To test the hypothesis, we assessed the expression of pro-/anti-inflammatory cytokines including TNF-α, IL-1β, IL-17 and IL-10 following tropisetron treatment in lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) derived from healthy subjects. Tropisetron up-regulates the transcription of TLR2, TLR4, JAK2 and STAT3 genes. Tropisetron also increases the expression of target pro-inflammatory cytokines, although considerably suppresses the pro-inflammatory cytokines (IL-1β, IL-17 and TNF-α) levels in media. Tropisetron notably promotes both IL-10 gene expression and secretion. These findings confirm the antiphlogistic properties of tropisetron. The present data also shed light on a new aspect of tropisetron immune-modulatory action that engaged TLR2, TLR4 and JAK2/STAT3 signalling cascades.

Acetylcholine Upregulates Entamoeba histolytica Virulence Factors, Enhancing Parasite Pathogenicity in Experimental Liver Amebiasis

Entamoeba histolytica is an invasive enteric protozoan, whose infections are associated to high morbidity and mortality rates. However, only less than 10% of infected patients develop invasive amebiasis. The ability of E. histolytica to adapt to the intestinal microenvironment could be determinant in triggering pathogenic behavior. Indeed, during chronic inflammation, the vagus nerve limits the immune response through the anti-inflammatory reflex, which includes acetylcholine (ACh) as one of the predominant neurotransmitters at the infection site. Consequently, the response of E. histolytica trophozoites to ACh could be implicated in the establishment of invasive disease. The aim of this study was to evaluate the effect of ACh on E. histolytica virulence. Methods include binding detection of ACh to plasma membrane, quantification of the relative expression of virulence factors by RT-PCR and western blot, evaluation of the effect of ACh in different cellular processes related to E. histolytica pathogenesis, and assessment of the capability of E. histolytica to migrate and form hepatic abscesses in hamsters. Results demonstrated that E. histolytica trophozoites bind ACh on their membrane and show a clear increase of the expression of virulence factors, that were upregulated upon stimulation with the neurotransmitter. ACh treatment increased the expression of L220, Gal/GalNAc lectin heavy subunit (170 kDa), amebapore C, cysteine proteinase 2 (ehcp-a2), and cysteine proteinase 5 (ehcp-a5). Moreover, erythrophagocytosis, cytotoxicity, and actin cytoskeleton remodeling were augmented after ACh treatment. Likewise, by assessing the formation of amebic liver abscess, we found that stimulated trophozoites to develop greater hamster hepatic lesions with multiple granulomas. In conclusion, ACh enhanced parasite pathogenicity by upregulating diverse virulence factors, thereby contributing to disease severity, and could be linked to the establishment of invasive amebiasis.

The role of the cholinergic anti-inflammatory pathway in septic cardiomyopathy

Septic cardiomyopathy (SCM)is common in septic patients and results in cardiovascular failure. The pathogenesis of SCM is complicated, and patients with SCM have high mortality because current treatment methods are limited. The cholinergic anti-inflammatory pathway (CAP) modulates inflammatory responses through vagus nerve stimulation that leads to the release of acetylcholine (ACh), which binds to the alpha7 nicotinic acetylcholine receptor (α7nAChR). Moreover, α7nAChR activation by its agonists at the tissue level inhibits inflammatory mediators and regulates the function of immune cells in sepsis. Therefore, the α7nAChR can maintain balance of the inflammatory-immune response in sepsis. CAP has been elucidated as a critical regulator of anti-inflammation in many diseases, including rheumatoid arthritis, inflammatory boweldisease and SCM. Additionally, some clinical and preclinical trials show therapeutic potential via regulating CAP. There are excellent studies regarding the beneficial role of CAP activation, especially α7nAChR, in experimental SCM. This review aims to discuss the CAP in attenuating inflammation and the potential role of α7nAChR activation in regulating immune and reducing inflammation in SCM.

Phospho-Tyr705 of STAT3 is a therapeutic target for sepsis through regulating inflammation and coagulation

BACKGROUND

Sepsis is an infection-induced aggressive and life-threatening organ dysfunction with high morbidity and mortality worldwide. Infection-associated inflammation and coagulation promote the progression of adverse outcomes in sepsis. Here, we report that phospho-Tyr705 of STAT3 (pY-STAT3), not total STAT3, contributes to systemic inflammation and coagulopathy in sepsis.

METHODS

Cecal ligation and puncture (CLP)-induced septic mice were treated with BP-1-102, Napabucasin, or vehicle control respectively and then assessed for systemic inflammation, coagulation response, lung function and survival. Human pulmonary microvascular endothelial cells (HPMECs) and Raw264.7 cells were exposed to lipopolysaccharide (LPS) with pharmacological or genetic inhibition of pY-STAT3. Cells were assessed for inflammatory and coagulant factor expression, cell function and signaling.

RESULTS

Pharmacological inhibition of pY-STAT3 expression by BP-1-102 reduced the proinflammatory factors, suppressed coagulation activation, attenuated lung injury, alleviated vascular leakage and improved the survival rate in septic mice. Pharmacological or genetic inhibition of pY-STAT3 diminished LPS-induced cytokine production in macrophages and protected pulmonary endothelial cells via the IL-6/JAK2/STAT3, NF-κB and MAPK signaling pathways. Moreover, the increase in procoagulant indicators induced by sepsis such as tissue factor (TF), the thrombin-antithrombin complex (TAT) and D-Dimer were down-regulated by pY-STAT3 inhibition.

CONCLUSIONS

Our results revealed a therapeutic role of pY-STAT3 in modulating the inflammatory response and defective coagulation during sepsis. Video Abstract.

Nicotinic Acetylcholine Receptors of PC12 Cells

Nicotinic acetylcholine receptors (nAChRs) have gained much attention in the scientific community since they play a significant role in multiple physiological and pathophysiological processes. Multiple approaches to study the receptors exist, with characterization of the receptors' functionality at a single cellular level using cell culturing being one of them. Derived from an adrenal medulla tumor, PC12 cells express nicotinic receptor subunits and form functional nicotinic receptors. Thus, the cells offer a convenient environment to address questions related to the functionality of the receptors. The review summarizes the findings on nicotinic receptors' expression and functions which were conducted using PC12 cells. Specific focus is given to α3-containing receptors as well as α7 receptor. Critical evaluation of findings is provided alongside insights into what can still be learned about nAChRs, using PC12 cells.

Inhibition of acetylcholinesterase attenuated retinal inflammation via suppressing NF-κB activation

Elevated inflammatory cytokines contribute to the pathogenesis of various retinal diseases such as diabetic retinopathy, retinal vasculitis and retinitis. However, the underlying mechanism of retinal inflammation remains largely unknown. Recent studies demonstrated that acetylcholinesterase (ACHE) is an inflammatory indicator in central neural system. This study was aimed to dissect the role of ACHE in retinal inflammation, and its mechanism of action. Retinal inflammation was induced by intravitreal injection of tumor necrosis factor-α (TNF-α) in heterozygous ACHE knockdown mice (ACHE^+/-) and wild type mice (ACHE^+/+). Donepezil, a well-known ACHE inhibitor, was administrated by daily gavage. Expression of ACHE and intercellular adherent molecule-1 (ICAM-1), infiltration of CD11b⁺ inflammatory cells, retinal leukostasis and vascular leakage was determined in both ACHE^+/- and ACHE^+/+ mice. ARPE-19 cells, a human retinal pigment epithelial cell line, were cultured for in vitro assay. Knockdown of ACHE was achieved by lipofectamine-mediated siRNA transfection and pharmaceutical suppression of ACHE was manipulated by donepezil. Cellular expression and distribution of ACHE, ICAM-1, and phosphorylation of NF-κB, IκB and IKKα/β were detected by western-blot analysis or immunocytochemistry. Retinal expression of ACHE was dramatically upregulated, in parallel with increased ICAM-1 expression, enhanced leukostasis and augmented CD11b⁺ inflammatory cell infiltration as well as vascular hyperpermeability in ACHE^+/+ mice injected with TNF-α. However, TNF-α-injected ACHE^+/- mice showed lower level of ICAM-1, less leukostasis and fewer infiltrated CD11b⁺ cells. Moreover, TNF-α-induced retinal vascular leakage was significantly reduced in ACHE^+/- mice. Similarly, TNF-α-induced retinal inflammatory response were also attenuated by donepezil intervention. In addition, TNF-α treatment resulted in significant induction of ACHE, upregulation of ICAM-1 and nuclear translocation of NF-κB, phosphorylation of IκB and IKKα/β in ARPE-19 cells. However, inhibition of ACHE reduced TNF-α-induced phosphorylation of NF-κB, IκB and IKKα/β in ARPE-19 cells. The present study reveals a pivotal role of ACHE in retinal inflammation. Inhibition of ACHE attenuates retinal inflammation and retinal leakage likely through suppressing NF-κB signaling activation.

Wharton's jelly-derived mesenchymal stem cells attenuate sepsis-induced organ injury partially via cholinergic anti-inflammatory pathway activation

Sepsis induces organ dysfunction due to overexpression of the inflammatory host response, resulting in cardiopulmonary and autonomic dysfunction, thus increasing the associated morbidity and mortality. Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) express genes and secrete factors with anti-inflammatory properties, neurological and immunological protection, as well as improve survival in experimental sepsis. The cholinergic anti-inflammatory pathway (CAP) is mediated by α7-nicotinic acetylcholine receptors (α7nAChRs), which play an important role in the control of systemic inflammation. We hypothesized that WJ-MSCs attenuate sepsis-induced organ injury in the presence of an activated CAP pathway. To confirm our hypothesis, we evaluated the effects of WJ-MSCs as a treatment for cardiopulmonary injury and on neuroimmunomodulation. Male Wistar rats were randomly divided into four groups: control (sham-operated); cecal ligation and puncture (CLP) alone; CLP+WJ-MSCs (1 × 10⁶ cells, at 6 h post-CLP); and CLP+methyllycaconitine (MLA)+WJ-MSCs (5 mg/kg body wt, at 5.5 h post-CLP, and 1 × 10⁶ cells, at 6 h post-CLP, respectively). All experiments, including the assessment of echocardiographic parameters and heart rate variability, were performed 24 h after CLP. WJ-MSC treatment attenuated diastolic dysfunction and restored baroreflex sensitivity. WJ-MSCs also increased cardiac sympathetic and cardiovagal activity. WJ-MSCs reduced leukocyte infiltration and proinflammatory cytokines, effects that were abolished by administration of a selective α7nAChR antagonist (MLA). In addition, WJ-MSC treatment also diminished apoptosis in the lungs and spleen. In cardiac and splenic tissue, WJ-MSCs downregulated α7nAChR expression, as well as reduced the phospho-STAT3-to-total STAT3 ratio in the spleen. WJ-MSCs appear to protect against sepsis-induced organ injury by reducing systemic inflammation, at least in part, via a mechanism that is dependent on an activated CAP.

Fish oils protects against cecal ligation and puncture‑induced septic acute kidney injury via the regulation of inflammation, oxidative stress and apoptosis

Septic acute kidney injury (AKI) is usually caused by sepsis. ω3 fatty acid has been reported to suppress sepsis-induced organ dysfunction to a certain degree. The present study aimed to investigate the effects of ω3 fatty acid in septic renal injury. Sprague Dawley rats were used to establish a cecal ligation and puncture (CLP) model in order to mimic the development of septic injury. The rats were treated with dexamethasone and fish oils (FOs) for 4 days prior to CLP. Alterations in the morphology of the tissues, the renal function and the induction of inflammation, oxidative stress and apoptosis were evaluated. The effects of FOs on nuclear factor-κB (NF-κB), JAK2/STAT3 and p38-MAPK were determined. The rats of the CLP model group exhibited low survival rates and increased expression of serum creatine, blood urea nitrogen, neutrophil gelatinase-associated lipocalin, kidney injury molecule-1 and of proinflammatory cytokines. In addition, the levels of the markers of oxidative injury and apoptosis were increased. The induction of renal injury was notably reversed by administration of dexamethasone and FOs. The expression levels of the protein markers involved in inflammation and apoptosis were measured and the results indicated that FOs inhibited JAK/STAT3 and p-38MAPK signaling, while they concomitantly increased the expression of NF-κB. The present study highlighted that FOs improve CLP-induced mortality and renal injury by inhibiting inflammation, oxidative stress and apoptosis.

Eliciting α7-nAChR exerts cardioprotective effects on ischemic cardiomyopathy via activation of AMPK signalling

Our previous studies have reported that agonist of α7 nicotinic acetylcholine receptors prevented electrophysiological dysfunction of rats with ischaemic cardiomyopathy (ICM) by eliciting the cholinergic anti‐inflammatory pathway (CAP). Adenosine monophosphate‐activated protein kinase (AMPK) signalling is widely recognized exerting cardioprotective effect in various cardiomyopathy. Here, we aimed to investigate whether the protective effects of the CAP are associated with AMPK signalling in ICM. In vivo, coronary artery of rats was ligated for 4 weeks to induce the ICM and then treated with PNU‐282987 (CAP agonist) and BML‐275 dihydrochloride (AMPK antagonist) for 4 weeks. In vitro, primary macrophages harvested from rats were induced inflammation by Lipopolysaccharide (LPS) treatment and then treated with PNU‐282987 and BML‐275 dihydrochloride. In vivo, exciting CAP by PUN‐282987 elicited an activation of AMPK signalling, alleviated ventricular remodeling, modified the cardiac electrophysiological function, reduced the cardiac expression of collagens and inflammatory cytokines and maintained the integrity of ultrastructure in the ischemic heart. However, the benefits of CAP excitation were blunted by AMPK signaling antagonization. In vitro, excitation of the CAP was observed inhibiting the nuclear transfer of NF‐κB p65 of macrophages and promoting the transformation of Ly‐6C^high macrophages into Ly‐6C^low macrophages. However, inhibiting AMPK signalling by BML‐275 dihydrochloride reversed the CAP effect on LPS‐treated macrophages. Finally, our findings suggest that eliciting the CAP modulates the inflammatory response in ICM through regulating AMPK signalling.

microRNA-30a inhibits the liver cell proliferation and promotes cell apoptosis through the JAK/STAT signaling pathway by targeting SOCS-1 in rats with sepsis

Sepsis is a systemic inflammatory response that may be induced by trauma, infection, surgery, and burns. With the aim of discovering novel treatment targets for sepsis, this current study was conducted to investigate the effect and potential mechanism by which microRNA-30a (miR-30a) controls sepsis-induced liver cell proliferation and apoptosis. Rat models of sepsis were established by applying the cecal ligation and puncture (CLP) method to simulate sepsis models. The binding site between miR-30a and suppressor of cytokine signaling protein 1 (SOCS-1) was determined by dual luciferase reporter gene assay. The gain-of-and-loss-of-function experiments were applied to analyze the effects of miR-30a and SOCS-1 on liver cell proliferation and apoptosis of the established sepsis rat models. The expression of miR-30a, SOCS-1, Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), Bcl-2 associated X protein (Bax), B cell lymphoma-2 (Bcl-2), toll-like receptor 4 (TLR4), and high-mobility group box 1 (HMGB1), and the extent of JAK2 and STAT3 phosphorylation were all determined. Sepsis led to an elevation of miR-30a and also a decline of SOCS-1 in the liver cells. SOCS-1 was negatively regulated by miR-30a. Upregulated miR-30a and downregulated SOCS-1 increased the expression of JAK2, STAT3, Bax, TLR4, and HMGB1 as well as the extent of JAK2 and STAT3 phosphorylation whereas impeding the expression of SOCS-1 and Bcl-2. More important, either miR-30a elevation or SOCS-1 silencing suppressed liver cell proliferation and also promoted apoptosis. On the contrary, the inhibition of miR-30a exhibited the opposite effects. Altogether, we come to the conclusion that miR-30a inhibited the liver cell proliferation and promoted cell apoptosis by targeting and negatively regulating SOCS-1 via the JAK/STAT signaling pathway in rats with sepsis.

Short-Term High-Fat Diet Consumption Reduces Hypothalamic Expression of the Nicotinic Acetylcholine Receptor α7 Subunit (α7nAChR) and Affects the Anti-inflammatory Response in a Mouse Model of Sepsis

Sepsis is one of the leading causes of death in hospitalized patients and the chronic and low-grade inflammation observed in obesity seems to worsen susceptibility and morbidity of infections. However, little is known with respect to a short-term high-fat diet (HFD) and its role in the development of sepsis. Here, we show for the first time, that short-term HFD consumption impairs early nicotinic acetylcholine receptor α7 subunit (α7nAChR)- mediated signaling, one of the major components of the cholinergic anti-inflammatory pathway, with a focus on hypothalamic inflammation and innate immune response. Mice were randomized to a HFD or standard chow (SC) for 3 days, and sepsis was subsequently induced by a lethal intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) or by cecal ligation and puncture (CLP) surgery. In a separate experiment, both groups received LPS (i.p.) or LPS (i.p.) in conjunction with the selective α7nAChR agonist, PNU-282987 (i.p. or intracerebroventricular; i.c.v.), and were sacrificed 2 h after the challenge. Short-term HFD consumption significantly reduced the α7nAChR mRNA and protein levels in the hypothalamus and liver (p < 0.05). Immunofluorescence microscopy demonstrated lower cholinergic receptor nicotinic α7 subunit (α7nAChR)+ cells in the arcuate nucleus (ARC) (α7nAChR+ cells in SC = 216 and HFD = 84) and increased F4/80+ cells in the ARC (2.6-fold) and median eminence (ME) (1.6-fold), which can contribute to neuronal damage. Glial fibrillary acidic protein (GFAP)+ cells and neuronal nuclear antigen (NeuN)+ cells were also increased following consumption of HFD. The HFD-fed mice died quickly after a lethal dose of LPS or following CLP surgery (2-fold compared with SC). The LPS challenge raised most cytokine levels in both groups; however, higher levels of TNF-α (Spleen and liver), IL-1β and IL-6 (in all tissues evaluated) were observed in HFD-fed mice. Moreover, PNU-282987 administration (i.p. or i.c.v.) reduced the levels of inflammatory markers in the hypothalamus following LPS injection. Nevertheless, when the i.c.v. injection of PNU-282987 was performed the anti-inflammatory effect was much smaller in HFD-fed mice than SC-fed mice. Here, we provide evidence that a short-term HFD impairs early α7nAChR expression in central and peripheral tissues, contributing to a higher probability of death in sepsis.

Sinomenine regulates CD14/TLR4, JAK2/STAT3 pathway and calcium signal via α7nAChR to inhibit inflammation in LPS-stimulated macrophages

Objective: To investigate the cellular mechanism that sinomenine (SIN) inhibits inflammation in macrophages induced by LPS through α7 nicotinic acetylcholine receptor (α7nAChR). Materials and methods: RAW264.7 cells were stimulated with LPS and treated by SIN or nicotine (Nic). A selective antagonist of α7nAChR, α-bungarotoxin (BTX) was used to block α7nAChR. AG490 was used to inhibit JAK2 activation. ELISA was performed to detect the levels of TNF-α and MCP-1. Western blotting was used to analyze the expression of MIF, MMP-9, CD14, TLR4, STAT3 and p-STAT3. Intracellular-free calcium level was measured by Fluorescent probe fluo-3/AM Results: SIN inhibited the production of TNF-α, MCP-1, MIF, and MMP-9, decreased the expression of CD14 and TLR4, and inhibited the release of intracellular-free calcium from intracellular stores in RAW 264.7 cells stimulated by LPS. JAK-specific inhibitor AG490 attenuated the inhibitory effect of SIN on TNF-α. SIN increased the phosphorylation of STAT3. And the above effects of SIN were attenuated by antagonist of α7nAChR. Conclusions: SIN can decrease the expression of CD14/TLR4 and intracellular free calcium level, activate JAK2/STAT3 pathway to inhibit inflammatory response through α7nAChR in macrophages.

Hepatic STAT3 inhibition amplifies the inflammatory response in obese mice during sepsis

The purpose of this study was to better understand the role obesity plays in the inflammatory response during sepsis, specifically regarding the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in the liver. We hypothesized that inhibiting STAT3 would lead to an increase in the inflammatory response and that obesity would amplify this effect. To investigate this, we inhibited STAT3 in two ways: pharmacological systemic inhibition and genetic hepatic-specific inhibition. In pharmacological inhibition studies, male C57BL/6 mice were randomized to a high-fat (60% kcal fat) or normal (16% kcal fat) diet for 6-7 wk and pretreated with Stattic before inducing sepsis by cecal ligation and puncture. In genetic inhibition studies, mice were randomized by genotype before induction of sepsis. To investigate obesity in mice with hepatic-specific STAT3 inhibition, we randomized mice to a high-fat or normal diet as described above for 6 mo before induction of sepsis. Body composition was analyzed using EchoMRI. We found that systemic STAT3 inhibition by Stattic resulted in an increased inflammatory response and that obesity amplified this effect. We also found that genetically inhibiting STAT3 in the liver resulted in higher mortality, increased inflammation, and liver injury. High-fat-fed mice with hepatic STAT3 inhibition gained more weight and had more fat than control mice on the same diet, and obesity increased neutrophil infiltration to the liver of these mice during sepsis. In conclusion, STAT3 plays an important regulatory role in the inflammatory response during sepsis, and obesity contributes to the dysregulated response observed when STAT3 is inhibited.

Activation of α7 Nicotinic Acetylcholine Receptor Ameliorates Zymosan-Induced Acute Kidney Injury in BALB/c Mice

Zymosan, a natural compound, provokes acute peritonitis and multiple organ dysfunction that affects the kidney, beside other organs via exaggerated inflammatory response. The aim of the present study is to test the role of cholinergic anti-inflammatory pathway (CAP) in alleviating acute kidney injury (AKI) induced by zymosan in BALB/c mice, using galantamine, a cholinesterase inhibitor, known to act via α7 nicotinic acetylcholine receptor (α7 nAChR) to stimulate CAP. Galantamine verified its anti-inflammatory effect by elevating acetylcholine (ACh) level, while abating the interleukin-6/ janus kinase 2 (Y1007/1008)/ signal transducer and activator of transcription 3 (Y705) (IL-6/ pY(1007/1008)-JAK2/ pY705-STAT3) inflammatory axis, with a consequent inhibition in suppressor of cytokine signaling 3 (SOCS3). This effect entails also the nuclear factor-kappa B (p65)/ high mobility group box protein-1/ (NF-κB (p65)/ HMGB-1) signaling pathway. Furthermore, the reno-curattive effect of galantamine was associated by a reduction in plasma creatinine (Cr), cystatin (Cys)-C, IL-18, and renal neutrophil gelatinase-associated lipocalin (NGAL), as well as an improved histopathological structure. Blocking the α7 nAChR by methyllycaconitine abolished the beneficial effect of galantamine to document the involvement of this receptor and the CAP in the amelioration of AKI induced by zymosan.

Neuroimmune Communication in Health and Disease

The immune and nervous systems are tightly integrated, with each system capable of influencing the other to respond to infectious or inflammatory perturbations of homeostasis. Recent studies demonstrating the ability of neural stimulation to significantly reduce the severity of immunopathology and consequently reduce mortality have led to a resurgence in the field of neuroimmunology. Highlighting the tight integration of the nervous and immune systems, afferent neurons can be activated by a diverse range of substances from bacterial-derived products to cytokines released by host cells. While activation of vagal afferents by these substances dominates the literature, additional sensory neurons are responsive as well. It is becoming increasingly clear that although the cholinergic anti-inflammatory pathway has become the predominant model, a multitude of functional circuits exist through which neuronal messengers can influence immunological outcomes. These include pathways whereby efferent signaling occurs independent of the vagus nerve through sympathetic neurons. To receive input from the nervous system, immune cells including B and T cells, macrophages, and professional antigen presenting cells express specific neurotransmitter receptors that affect immune cell function. Specialized immune cell populations not only express neurotransmitter receptors, but express the enzymatic machinery required to produce neurotransmitters, such as acetylcholine, allowing them to act as signaling intermediaries. Although elegant experiments have begun to decipher some of these interactions, integration of these molecules, cells, and anatomy into defined neuroimmune circuits in health and disease is in its infancy. This review describes these circuits and highlights continued challenges and opportunities for the field.

From neuroimunomodulation to bioelectronic treatment of rheumatoid arthritis

Neuronal stimulation is an emerging field in modern medicine to control organ function and reestablish physiological homeostasis during illness. The nervous system innervates most of the peripheral organs and provides a fine tune to control the immune system. Most of these studies have focused on vagus nerve stimulation and the physiological, cellular and molecular mechanisms regulating the immune system. Here, we review the new results revealing afferent vagal signaling pathways, immunomodulatory brain structures, spinal cord-dependent circuits, neural and non-neural cholinergic/catecholaminergic signals and their respective receptors contributing to neuromodulation of inflammation in rheumatoid arthritis. These new neuromodulatory networks and structures will allow the design of innovative bioelectronic or pharmacological approaches for safer and low-cost treatment of arthritis and related inflammatory disorders.

The crosstalk between autonomic nervous system and blood vessels

The autonomic nervous system (ANS), comprised of two primary branches, sympathetic and parasympathetic nervous system, plays an essential role in the regulation of vascular wall contractility and tension. The sympathetic and parasympathetic nerves work together to balance the functions of autonomic effector organs. The neurotransmitters released from the varicosities in the ANS can regulate the vascular tone. Norepinephrine (NE), adenosine triphosphate (ATP) and Neuropeptide Y (NPY) function as vasoconstrictors, whereas acetylcholine (Ach) and calcitonin gene-related peptide (CGRP) can mediate vasodilation. On the other hand, vascular factors, such as endothelium-derived relaxing factor nitric oxide (NO), and constriction factor endothelin, play an important role in the autonomic nervous system in physiologic conditions. Endothelial dysfunction and inflammation are associated with the sympathetic nerve activity in the pathological conditions, such as hypertension, heart failure, and diabetes mellitus. The dysfunction of the autonomic nervous system could be a risk factor for vascular diseases and the overactive sympathetic nerve is detrimental to the blood vessel. In this review, we summarize findings concerning the crosstalk between ANS and blood vessels in both physiological and pathological conditions and hope to provide insight into the development of therapeutic interventions of vascular diseases.

Interleukin-6 promotes a sustained loss of endothelial barrier function via Janus kinase-mediated STAT3 phosphorylation and de novo protein synthesis

Vascular leakage is a hallmark of the inflammatory response. Acute changes in endothelial permeability are due to posttranslational changes in intercellular adhesion and cytoskeleton proteins. However, little is known about the mechanisms leading to long-term changes in vascular permeability. Here, we show that interleukin-6 (IL-6) promotes an increase in endothelial monolayer permeability that lasts over 24 h and demonstrate that activation of Src and MEK/ERK pathways is required only for short-term increases in permeability, being dispensable after 2 h. In contrast, Janus kinase (JAK)-mediated STAT3 phosphorylation at Y705 (but not S727) and de novo synthesis of RNA and proteins are required for the sustained permeability increases. Loss of junctional localization of VE-cadherin and ZO-1 is evident several hours after the maximal IL-6 response, thus suggesting that these events are a consequence of IL-6 signaling, but not a cause of the increased permeability. Understanding the mechanisms involved in sustaining vascular permeability may prove crucial to allow us to directly target vascular leakage and minimize tissue damage, thus reducing the rates of mortality and chronic sequelae of excessive edema. Targeting endothelial-specific mechanisms regulating barrier function could provide a new therapeutic strategy to prevent vascular leakage while maintaining the immune response and other beneficial aspects of the inflammatory response that are required for bacterial clearance and tissue repair.

Anti-inflammatory effect and mechanism of the spirocyclopiperazinium salt compound LXM-15 in rats and mice

OBJECTIVE

This study aimed to investigate the anti-inflammatory effects of a novel spirocyclopiperazinium salt compound LXM-15, and explore the underlying mechanisms.

METHODS

Xylene-induced mouse ear oedema and carrageenan-induced rat paw oedema tests were used to evaluate the anti-inflammatory effects of LXM-15. The protein levels of TNF-α, IL-6, phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) were detected by ELISA or Western blot analysis. Additionally, receptor blocking test was performed to explore the possible target.

RESULTS

Intragastric administration with LXM-15 (2, 1, 0.5 mg/kg in mice, and 6, 3, 1.5 mg/kg in rats) produced distinct anti-inflammatory effects in vivo, the highest inhibition percentage was 60 and 52%, respectively (P < 0.01). Following treatment with LXM-15 (6 mg/kg, i.g.), the levels of TNF-α and IL-6 in the rats paws were attenuated by 40 and 41%; and the phosphorylation of JAK2 and STAT3 was restrained by 35 and 45%, respectively (P < 0.01). All effects of LXM-15 were blocked by pretreatment with methyllycaconitine citrate or tropicamide.

CONCLUSION

This study provides the first report that the spirocyclopiperazinium salt compound LXM-15 displays considerable anti-inflammatory effects. The underlying mechanism may be through activating the peripheral α7 nicotinic acetylcholine receptor and M4 muscarinic acetylcholine receptor, leading to the inhibition of the JAK2/STAT3 signalling pathway, eventually resulting in the reduction of TNF-α and IL-6.

Cholinergic and cytoprotective signaling cascades mediate the mitigative effect of erythropoietin on acute radiation syndrome

The present investigation aimed to evaluate the radiomitigative efficacy of the recombinant human erythropoietin (EPO) against acute radiation syndrome (ARS) in a rat model. Rats were irradiated with a single sublethal dose of γ-radiation (7 Gy; total body irradiation; TBI) on the 1st day of experimental course, then received EPO (5000 IU/kg; i.p.) 24 h after irradiation, and rats were observed for 30 days of survival analysis. Administration of EPO improved 30-day survival, alleviated TBI-induced myelosuppression and pancytopenia, by augmenting lymphocytes and other white blood cells in the peripheral blood of rats, while bone marrow and spleen cellularity were restored. EPO post-exposure treatment alleviated hepatotoxicity biomarkers and restored splenic function. EPO abrogated radiation-induced oxidative stress through the upregulation of the cholinergic anti-inflammatory nicotinic acetylcholine receptor (α-7-nAChR) and the pro-survival Janus kinase-2 and signal transducers and activators of transcription JAK-2/STAT-3 signaling mediated via enhancing nuclear factor erythroid-2 related factor-2 (Nrf-2) cytoprotective machinery in liver and spleen of irradiated rats. Moreover, EPO treatment prevented hepatic and splenic apoptosis. The present study establishes the implication of α-7-nAChR-JAK-2/STAT-3-Nrf-2 signaling cascade in the radiomitigative potential of EPO against ARS.

Nerve Stimulation: Immunomodulation and Control of Inflammation

Neuronal stimulation is an emerging field in modern medicine to control organ function and re-establish physiological homeostasis during illness. Transdermal nerve stimulation with electroacupuncture is currently endorsed by the World Health Organization (WHO) and the National Institutes of Health (NIH), and is used by millions of people to control pain and inflammation. Recent advances in electroacupuncture may permit activation of specific neuronal networks to prevent organ damage in inflammatory and infectious disorders. Experimental studies of nerve stimulation are also providing new information on the functional organization of the nervous system to control inflammation and its clinical implications in infectious and inflammatory disorders. These studies may allow the design of novel non-invasive techniques for nerve stimulation to help to control immune and organ functions.

Targeting neural reflex circuits in immunity to treat kidney disease

Neural pathways regulate immunity and inflammation via the inflammatory reflex and specific molecular targets can be modulated by stimulating neurons. Neuroimmunomodulation by nonpharmacological methods is emerging as a novel therapeutic strategy for inflammatory diseases, including kidney diseases and hypertension. Electrical stimulation of vagus neurons or treatment with pulsed ultrasound activates the cholinergic anti-inflammatory pathway (CAP) and protects mice from acute kidney injury (AKI). Direct innervation of the kidney, by afferent and efferent neurons, might have a role in modulating and responding to inflammation in various diseases, either locally or by providing feedback to regions of the central nervous system that are important in the inflammatory reflex pathway. Increased sympathetic drive to the kidney has a role in the pathogenesis of hypertension, and selective modulation of neuroimmune interactions in the kidney could potentially be more effective for lowering blood pressure and treating inflammatory kidney diseases than renal denervation. Use of optogenetic tools for selective stimulation of specific neurons has enabled the identification of neural circuits in the brain that modulate kidney function via activation of the CAP. In this Review we discuss evidence for a role of neural circuits in the control of renal inflammation as well as the therapeutic potential of targeting these circuits in the settings of AKI, kidney fibrosis and hypertension.

SOCS1 is a negative regulator of metabolic reprogramming during sepsis

Sepsis can induce an overwhelming systemic inflammatory response, resulting in organ damage and death. Suppressor of cytokine signaling 1 (SOCS1) negatively regulates signaling by cytokine receptors and Toll-like receptors (TLRs). However, the cellular targets and molecular mechanisms for SOCS1 activity during polymicrobial sepsis are unknown. To address this, we utilized a cecal ligation and puncture (CLP) model for sepsis; C57BL/6 mice subjected to CLP were then treated with a peptide (iKIR) that binds the SOCS1 kinase inhibitory region (KIR) and blocks its activity. Treatment with iKIR increased CLP-induced mortality, bacterial burden, and inflammatory cytokine production. Myeloid cell-specific SOCS1 deletion (Socs1Δmyel) mice were also more susceptible to sepsis, demonstrating increased mortality, higher bacterial loads, and elevated inflammatory cytokines, compared with Socs1fl littermate controls. These effects were accompanied by macrophage metabolic reprograming, as evidenced by increased lactic acid production and elevated expression of the glycolytic enzymes hexokinase, lactate dehydrogenase A, and glucose transporter 1 in septic Socs1Δmyel mice. Upregulation was dependent on the STAT3/HIF-1α/glycolysis axis, and blocking glycolysis ameliorated increased susceptibility to sepsis in iKIR-treated CLP mice. These results reveal a role of SOCS1 as a regulator of metabolic reprograming that prevents overwhelming inflammatory response and organ damage during sepsis.

Activation of the α7 nicotinic receptor promotes lipopolysaccharide-induced conversion of M1 microglia to M2

The α7 subtype of the nicotinic acetylcholine receptor (α7 nAChR) plays an essential role in the cholinergic anti-inflammatory pathway that regulates macrophage/microglia function in inflammation. Similar to M1 and M2 macrophages, M1 and M2 microglia exhibit pro-inflammation and anti-inflammation properties, respectively. In the present study, we analyzed function-associated phenotypes to detect the transformation of microglia with activation of α7 nAChRs. We used lentivirus-mediated shRNA to knockdown the expression of α7 nAChR in BV-2 microglia incubated with lipopolysaccharides (LPS, 0.1 μg/mL) and measured the acetylcholine (Ach, 1 μg/mL)-mediated release of cytokines, such as IL-1β, IL-4, IL-6, and IL-10, in the culture supernatant via radioimmunoassay. After stimulation with Ach, the expression of typical biomarkers for different microglia phenotypes, Iba-1 and Arg-1, was determined by cellular immunofluorescence. Furthermore, the expression of signaling molecules, including p38, JAK2/STAT3, PI3K/Akt and miR-124, was analyzed via western blotting and real-time PCR. We found that Ach inhibited LPS-induced IL-1β and IL-6 elevation and promoted IL-4 and IL-10 production and that knockdown of the α7 nAChR abolished these effects of Ach. In addition, Ach decreased LPS-induced Iba-1 expression and increased Arg-1 levels in an α7 nAChR-dependent manner. The LPS-inhibited activation of JAK2/STAT3 and PI3K/Akt was also rescued by Ach, an effect that was blocked by knockdown of the α7 nAChR. In contrast, Ach triggered the phosphorylation of JAK2 and STAT3 that was otherwise inactivated by LPS in BV-2 cells. Finally, the levels of miR-124 and downstream targets C/EBPα and PU.1 were significantly enhanced in LPS-treated BV-2 microglia, and the effect of Ach on this signaling pathway was blocked by α7 nAChR knockdown as expected. Overall, our data demonstrate that activation ofα7 nAChRs inhibits the transformation of M1 microglia and promotes the M2 phenotype, contributing to the modulation of vagus nerve neuroinflammation during several central nervous system diseases.

Neuro-immune interactions in the cholinergic anti-inflammatory reflex

Communication between the nervous and immune systems can significantly alter immune cell function in a number of inflammatory diseases. Elegant studies have defined a basic functional circuit in a "cholinergic anti-inflammatory pathway" that highlights a unique role for the vagus nerve, and has brought about a resurgence in the field of neuro-immunology. This research has further identified that in addition to tonic signals that can restrain immune cell activation; the anti-inflammatory reflex arc is amiable to targeted stimulation as a therapeutic modality. The success of vagal electrical neural stimulation in a plethora of pre-clinical inflammation models has spurred the development of "electroceuticals" or neurostimulatory devices in the treatment of chronic inflammation. This development has begun despite addressing of fundamental questions such as the functional neural circuitry being crudely mapped and unresolved mechanisms of action of acetylcholine on target immune cells. Perhaps fortuitously, rapid advances in neuroscience techniques may allow us to begin to answer some of these longstanding questions and clarify recent controversies.

Nicotinic α7 receptor inhibits the acylation stimulating protein‑induced production of monocyte chemoattractant protein‑1 and keratinocyte‑derived chemokine in adipocytes by modulating the p38 kinase and nuclear factor‑κB signaling pathways

Obesity is associated with chronic low-grade inflammation, which is characterized by increased infiltration of macrophages into adipose tissue. Acylation stimulating protein (ASP) is an adipokine derived from the immune complement system, which constitutes a link between adipocytes and macrophages, and is involved in energy homeostasis and inflammation. The purpose of the present study was to preliminarily investigate in vitro, whether functional α7nAChR in adipocytes may suppress ASP-induced inflammation and determine the possible signaling mechanism. Studies have reported associations between the expression of α7 nicotinic acetylcholine receptor (α7nAChR) and obesity, insulin resistance and diabetes. Additionally, α7nAChRs are important peripheral mediators of chronic inflammation, which is a key contributor to health problems in obesity. The primary aim of the present study was to evaluate the impact of exogenous ASP and α7nAChR on macrophage infiltration in adipose tissue and to examine the potential underlying molecular mechanism. Western blot analysis revealed that recombinant ASP increased the expression levels of monocyte chemoattractant protein-1 (MCP-1) and keratinocyte-derived chemokine (KC) by 3T3-L1 adipocytes. However, nicotine significantly inhibited the production of ASP-induced cytokines via the stimulation of α7nAChR. It was also found that α7nAChR inhibited the ASP-induced activation of p38 kinase and nuclear factor-κB (NF-κB), and the production of MCP-1 and KC. These data indicated that α7nAChR caused the inhibition of ASP-induced activation of p38 kinase and NF-κB to inhibit the production of MCP-1 and KC.