Nicotine inhibits the production of proinflammatory mediators in human monocytes by suppression of I-kappaB phosphorylation and nuclear factor-kappaB transcriptional activity through nicotinic acetylcholine receptor alpha7

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 and yet it can also lead to irreversible tissue damage, especially in the respiratory tract. Sensitive regulators must exist that modulate inflammation, while controlling the infection. In the present study, we identified acetylcholine (ACh)-producing B cells as such early regulators. B cells are the most prevalent ACh-producing leukocyte population in the respiratory tract demonstrated with choline acetyltransferase (ChAT)-green fluorescent protein (GFP) reporter mice, both before and after infection with influenza A virus. Mice lacking ChAT in B cells, disabling their ability to generate ACh (ChatBKO), but not those lacking ChAT in T cells, significantly, selectively and directly suppressed α7-nicotinic-ACh receptor-expressing interstitial, but not alveolar, macrophage activation and their ability to secrete tumor necrosis factor (TNF), while better controlling virus replication at 1 d postinfection. Conversely, TNF blockade via monoclonal antibody treatment increased viral loads at that time. By day 10 of infection, ChatBKO mice showed increased local and systemic inflammation and reduced signs of lung epithelial repair despite similar viral loads and viral clearance. Thus, B cells are key participants of an immediate early regulatory cascade that controls lung tissue damage after viral infection, shifting the balance toward reduced inflammation at the cost of enhanced early viral replication.

Developmental drugs for sarcoidosis

Sarcoidosis is a multi-organ granulomatous inflammatory disease of unknown etiology. Over 50% of patients will require treatment at some point in their disease and 10%-30% will develop a chronic progressive disease with pulmonary fibrosis leading to significant morbidity and mortality. Recently published guidelines recommend immunosuppressive therapy for sarcoidosis patients at risk of increased disease-related morbidity and mortality, and in whom disease has negatively impacted quality of life. Prednisone the currently recommended first line therapy is associated with significant toxicity however none of the other guideline recommended steroid sparing therapy is approved by regulatory agencies for use in sarcoidosis, and data in support of their use is weak. For patients with severe refractory disease requiring prolonged therapy, treatment options are limited. The need for expanding treatment options in sarcoidosis has been emphasized. Well conducted large, randomized trials evaluating currently available therapeutic options as well as novel pathways for targeting disease are necessary to better guide treatment decisions. These trials will not be without significant challenges. Sarcoidosis is a rare disease with heterogenous presentation and variable progression and clinical outcome. There are no universally agreed upon biomarkers of disease activity and measurement of outcomes is confounded by the need to balance patient centric measures and objective measures of disease activity. Our paper provides an update on developmental drugs in sarcoidosis and outlines several novel pathways that may be targeted for future drug development. Currently available trials are highlighted and ongoing challenges to drug development and clinical trial design are briefly discussed.

Microbiota-immune-brain interactions: A new vision in the understanding of periodontal health and disease

This review highlights the significance of interactions between the microbiota, immune system, nervous and hormonal systems, and the brain on periodontal health and disease. Microorganisms in the microbiota, immune cells, and neurons communicate via homeostatic nervous and hormonal systems, regulating vital body functions. By modulating pro-inflammatory and anti-inflammatory adaptive immune responses, these systems control the composition and number of microorganisms in the microbiota. The strength of these brain-controlled responses is genetically determined but is sensitive to early childhood stressors, which can permanently alter their responsiveness via epigenetic mechanisms, and to adult stressors, causing temporary changes. Clinical evidence and research with humans and animal models indicate that factors linked to severe periodontitis enhance the responsiveness of these homeostatic systems, leading to persistent hyperactivation. This weakens the immune defense against invasive symbiotic microorganisms (pathobionts) while strengthening the defense against non-invasive symbionts at the gingival margin. The result is an increased gingival tissue load of pathobionts, including Gram-negative bacteria, followed by an excessive innate immune response, which prevents infection but simultaneously destroys gingival and periodontal tissues. Thus, the balance between pro-inflammatory and anti-inflammatory adaptive immunity is crucial in controlling the microbiota, and the responsiveness of brain-controlled homeostatic systems determines periodontal health.

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.

Suppression by central adenosine A3 receptors of the cholinergic defense against cardiovascular aberrations of sepsis: role of PI3K/MAPKs/NFκB signaling

Introduction: Despite the established role of peripheral adenosine receptors in sepsis-induced organ dysfunction, little or no data is available on the interaction of central adenosine receptors with sepsis. The current study tested the hypothesis that central adenosine A3 receptors (A3ARs) modulate the cardiovascular aberrations and neuroinflammation triggered by sepsis and their counteraction by the cholinergic antiinflammatory pathway. Methods: Sepsis was induced by cecal ligation and puncture (CLP) in rats pre-instrumented with femoral and intracisternal (i.c.) catheters for hemodynamic monitoring and central drug administration, respectively. Results: The CLP-induced hypotension, reduction in overall heart rate variability (HRV) and sympathovagal imbalance towards parasympathetic predominance were abolished by i.v. nicotine (100 μg/kg) or i.c. VUF5574 (A3AR antagonist, 2 µg/rat). In addition, the selective A3AR agonist, 3-iodobenzyl-5'-N-methylcarboxamidoadenosine IB-MECA, 4 µg/rat, i.c.) exaggerated the hypotension and cardiac autonomic dysfunction induced by sepsis and opposed the favorable nicotine actions against these septic manifestations. Immunohistochemically, IB-MECA abolished the nicotine-mediated downregulation of NFκB and NOX2 expression in rostral ventrolateral medullary areas (RVLM) of brainstem of septic rats. The inhibitory actions of IB-MECA on nicotine responses disappeared after i.c. administration of PD98059 (MAPK-ERK inhibitor), SP600125 (MAPK-JNK inhibitor) or wortmannin (PI3K inhibitor). Moreover, infliximab (TNFα inhibitor) eliminated the IB-MECA-induced rises in RVLM-NFκB expression and falls in HRV, but not blood pressure. Conclusion: Central PI3K/MAPKs pathway mediates the A3AR counteraction of cholinergic defenses against cardiovascular and neuroinflammatory aberrations in sepsis.

Exposing the latent phenotype of Gulf War Illness: examination of the mechanistic mediators of cognitive dysfunction

Though it has been over 30 years since the 1990-1991 Gulf War (GW), the pathophysiology of Gulf War Illness (GWI), the complex, progressive illness affecting approximately 30% of GW Veterans, has not been fully characterized. While the symptomology of GWI is broad, many symptoms can be attributed to immune and endocrine dysfunction as these critical responses appear to be dysregulated in many GWI patients. Since such dysregulation emerges in response to immune threats or stressful situations, it is unsurprising that clinical studies suggest that GWI may present with a latent phenotype. This is most often observed in studies that include an exercise challenge during which many GWI patients experience an exacerbation of symptoms. Unfortunately, very few preclinical studies include such physiological stressors when assessing their experimental models of GWI, which creates variable results that hinder the elucidation of the mechanisms mediating GWI. Thus, the purpose of this review is to highlight the clinical and preclinical findings that investigate the inflammatory component of GWI and support the concept that GWI may be characterized as having a latent phenotype. We will mainly focus on studies assessing the progressive cognitive impairments associated with GWI and emphasize the need for physiological stressors in future work to create a more unified hypothesis that can identify potential therapeutics for this patient population.

Brain-Gut Axis: Invasive and Noninvasive Vagus Nerve Stimulation, Limitations, and Potential Therapeutic Approaches

Inflammatory bowel disease (IBD) is a chronic relapsing condition with no known etiology and is characterized by disrupted gut homeostasis, chronic inflammation, and ulcerative lesions. Although current treatments can reduce disease activity, IBD frequently recurs once treatments are discontinued, indicating that treatments are ineffective in providing long-term remission. The lack of responsiveness and reluctance of some affected persons to take medications because of potential adverse effects has enhanced the need for novel therapeutic approaches. The vagus nerve (VN) is likely important in the pathogenesis of IBD, considering the decreased activity of the parasympathetic nervous system, especially the VN, and the impaired interaction between the enteric nervous system and central nervous system in patients with IBD. Vagus nerve stimulation (VNS) has demonstrated anti-inflammatory effects in various inflammatory disorders, including IBD, by inhibiting the production of inflammatory cytokines by immune cells. It has been suggested that stimulating the vagus nerve to induce its anti-inflammatory effects may be a potential therapeutic approach for IBD. Noninvasive techniques for VNS have been developed. Considering the importance of VN function in the brain-gut axis, VNS is a promising treatment option for IBD. This review discusses the potential therapeutic advantages and drawbacks of VNS, particularly the use of noninvasive transcutaneous auricular vagus nerve stimulation.

Tropisetron attenuates neuroinflammation and chronic neuropathic pain via α7nAChR activation in the spinal cord in rats

OBJECTIVES

Tropisetron is an alpha 7 nicotinic acetylcholine receptor (α7nAChR) agonist and is a commonly used antiemetic clinically. α7nAChRs activation modulating nociception transmissions and cholinergic anti-inflammation may decrease neuropathic pain. This study was set to investigate the effects of tropisetron on neuropathic pain and neuroinflammation as well as the underlying mechanisms in rats.

METHODS

Neuropathic pain behavior was assessed in rats using the paw mechanical withdrawal threshold and paw thermal withdrawal latency before and after the establishment of a spared nerve injury (SNI) pain model in rats treated with tropisetron treatment in the presence or absence of the α7nAChR antagonist methyllycaconitine (MLA) through intrathecal injection. Their spinal cords were then harvested for inflammatory cytokines, the α7nAChR, p38 mitogen-activated protein kinase (p-p38MAPK) and cAMP-response element binding protein (CREB) measurement.

RESULTS

Tropisetron effectively alleviated mechanical allodynia and thermal hyperalgesia; decreased IL-6, IL-1ß and TNF-a; and down-regulated the phosphorylation of p38MAPK and CREB. Pre-treatment with MLA abolished these effects of tropisetron.

CONCLUSION

Our data indicate that tropisetron alleviates neuropathic pain may through inhibition of the p38MAPK-CREB pathway via α7nAChR activation. Thus, tropisetron may be a potential new therapeutic strategy for chronic neuropathic pain.

Nicotinic receptors in airway disease

With continued smoking of tobacco products and expanded use of nicotine delivery devices worldwide, understanding the impact of smoking and vaping on respiratory health remains a major global unmet need. Although multiple studies have shown a strong association between smoking and asthma, there is a relative paucity of mechanistic understanding of how elements in cigarette smoke impact the airway. Recognizing that nicotine is a major component in both smoking and vaping products, it is critical to understand the mechanisms by which nicotine impacts airways and promotes lung diseases such as asthma. There is now increasing evidence that α7 nicotinic acetylcholine receptors (α7nAChRs) are critical players in nicotine effects on airways, but the mechanisms by which α7nAChR influences different airway cell types have not been widely explored. In this review, we highlight and integrate the current state of knowledge regarding nicotine and α7nAChR in the context of asthma and identify potential approaches to alleviate the impact of smoking and vaping on the lungs.

Revealing the clinical effect and biological mechanism of acupuncture in COPD: A review

BACKGROUND

To provide new ideas for the clinical and mechanism research of acupuncture in the treatment of chronic obstructive pulmonary disease (COPD), this study systematically reviews clinical research and the progress of basic research of acupuncture in the treatment of COPD.

METHODS

PubMed and Web of Science databases were searched using acupuncture and COPD as keywords in the last 10 years, and the included literature was determined according to exclusion criteria.

FINDINGS

Acupuncture can relieve clinical symptoms, improve exercise tolerance, anxiety, and nutritional status, as well as hemorheological changes (blood viscosity), reduce the inflammatory response, and reduce the duration and frequency of COPD in patients with COPD. Mechanistically, acupuncture inhibits M1 macrophage activity, reduces neutrophil infiltration, reduces inflammatory factor production in alveolar type II epithelial cells, inhibits mucus hypersecretion of airway epithelial cells, inhibits the development of chronic inflammation in COPD, and slows tissue structure destruction. Acupuncture may control pulmonary COPD inflammation through the vagal-cholinergic anti-inflammatory, vagal-adrenomedullary-dopamine, vagal-dual-sensory nerve fiber-pulmonary, and CNS-hypothalamus-orexin pathways. Furthermore, acupuncture can increase endogenous cortisol levels by inhibiting the HPA axis, thus improving airway antioxidant capacity and reducing airway inflammation in COPD. In conclusion, the inhibition of the chronic inflammatory response is the key mechanism of acupuncture treatment for COPD.

Anti-inflammatory effects of acupuncture in the treatment of chronic obstructive pulmonary disease

Numerous randomised controlled trials have suggested the positive effects of acupuncture on chronic obstructive pulmonary disease (COPD). However, the underlying therapeutic mechanisms of acupuncture for COPD have not been clearly summarized yet. Inflammation is central to the development of COPD. In this review, we elucidate the effects and underlying mechanisms of acupuncture from an anti-inflammatory perspective based on animal studies. Cigarette smoke combined with lipopolysaccharide is often used to establish animal models of COPD. Electroacupuncture can be an effective intervention to improve inflammation in COPD, and Feishu (BL13) and Zusanli (ST36) can be used as basic acupoints in COPD animal models. Different acupuncture types can regulate different types of inflammatory cytokines; meanwhile, different acupuncture types and acupoint options have similar effects on modulating the level of inflammatory cytokines. In particular, acupuncture exerts anti-inflammatory effects by inhibiting the release of inflammatory cells, inflammasomes and inflammatory cytokines. The main underlying mechanism through which acupuncture improves inflammation in COPD is the modulation of relevant signalling pathways: nuclear factor-κB (NF-κB) (e.g., myeloid differentiation primary response 88/NF-κB, toll-like receptor-4/NF-κB, silent information regulator transcript-1/NF-κB), mitogen-activated protein kinase signalling pathways (extracellular signal-regulated kinase 1/2, p38 and c-Jun NH2-terminal kinase), cholinergic anti-inflammatory pathway, and dopamine D2 receptor pathway. The current synthesis will be beneficial for further research on the effect of acupuncture on COPD inflammation. Please cite this article as: Jiang LH, Li PJ, Wang YQ, Jiang ML, Han XY, Bao YD, Deng XL, Wu WB, Liu XD. Anti-inflammatory effects of acupuncture in the treatment of chronic obstructive pulmonary disease. J Integr Med. 2023; 21(6): 518-527.

Immuno-physiological effects of dietary reishi mushroom powder as a source of beta-glucan on Rohu, Labeo rohita challenged with Aeromonas veronii

Beta-glucans have immense potential to stimulate immune modulation in fish by being injected intramuscularly, supplemented with feed or immersion routes of administration. We studied how supplementing Labeo rohita's diet with reishi mushroom powder containing beta-glucan influenced immunological function. A supplemented diet containing 10% reishi mushroom powder was administered for 120 days. Afterwards, analyses were conducted on different immunological parameters such as antioxidants, respiratory burst, reactive oxygen species (ROS), alternative complement activity, and serum immunoglobulin, which resulted significant increases (p < 0.05; p < 0.01) for the reishi mushroom-fed immune primed L. rohita. Additionally, analyzing various hematological parameters such as erythrocytes and leukocytes count were assessed to elucidate the immunomodulatory effects, indicating positive effects of dietary reishi mushroom powder on overall fish health. Furthermore, the bacterial challenge-test with 1.92 × 104 CFU/ml intramuscular dose of Aeromonas veronii showed enhanced disease-defending system as total serum protein and lysozyme activity levels accelerated significantly (p < 0.01). Nevertheless, reishi mushroom powder contained with beta-glucan ameliorated the stress indicating parameters like acetylcholinesterase (AChE), serum-glutamic pyruvic transaminase (SGPT) and serum-glutamic oxaloacetic transaminase (SGOT) enzyme activities results suggested the fish's physiology was unaffected. Therefore, the results indicated that adding dietary reishi mushroom as a source of beta-glucan could significantly boost the immune responses in Rohu.

Alpha 7 nicotinic acetylcholine receptors signaling boosts cell-cell interactions in macrophages effecting anti-inflammatory and organ protection

Activation of the cholinergic anti-inflammatory pathway (CAP) via vagus nerve stimulation has been shown to improve acute kidney injury in rodent models. While alpha 7 nicotinic acetylcholine receptor (α7nAChR) positive macrophages are thought to play a crucial role in this pathway, their in vivo significance has not been fully understood. In this study, we used macrophage-specific α7nAChR-deficient mice to confirm the direct activation of α7nAChRs in macrophages. Our findings indicate that the administration of GTS-21, an α7nAChR-specific agonist, protects injured kidneys in wild-type mice but not in macrophage-specific α7nAChR-deficient mice. To investigate the signal changes or cell reconstructions induced by α7nAChR activation in splenocytes, we conducted single-cell RNA-sequencing of the spleen. Ligand-receptor analysis revealed an increase in macrophage-macrophage interactions. Using macrophage-derived cell lines, we demonstrated that GTS-21 increases cell contact, and that the contact between macrophages receiving α7nAChR signals leads to a reduction in TNF-α. Our results suggest that α7nAChR signaling increases macrophage-macrophage interactions in the spleen and has a protective effect on the kidneys.

The controversial effect of smoking and nicotine in SARS-CoV-2 infection

The effects of nicotine and cigarette smoke in many diseases, notably COVID-19 infection, are being debated more frequently. The current basic data for COVID-19 is increasing and indicating the higher risk of COVID-19 infections in smokers due to the overexpression of corresponding host receptors to viral entry. However, current multi-national epidemiological reports indicate a lower incidence of COVID-19 disease in smokers. Current data indicates that smokers are more susceptible to some diseases and more protective of some other. Interestingly, nicotine is also reported to play a dual role, being both inflammatory and anti-inflammatory. In the present study, we tried to investigate the effect of pure nicotine on various cells involved in COVID-19 infection. We followed an organ-based systematic approach to decipher the effect of nicotine in damaged organs corresponding to COVID-19 pathogenesis (12 related diseases). Considering that the effects of nicotine and cigarette smoke are different from each other, it is necessary to be careful in generalizing the effects of nicotine and cigarette to each other in the conducted researches. The generalization and the undifferentiation of nicotine from smoke is a significant bias. Moreover, different doses of nicotine stimulate different effects (dose-dependent response). In addition to further assessing the role of nicotine in COVID-19 infection and any other cases, a clever assessment of underlying diseases should also be considered to achieve a guideline for health providers and a personalized approach to treatment.

Nicotine Administration Augments Abdominal Aortic Aneurysm Progression in Rats

Inflammation and elastin degradation are key hallmarks in the pathogenesis of abdominal aortic aneurysms (AAAs). It has been acknowledged that activation of alpha7 nicotinic acetylcholine receptors (α7nAChRs) attenuates inflammation, termed the cholinergic anti-inflammatory pathway (CAP). Thus, we hypothesize that low-dose nicotine impairs the progression of elastase-induced AAAs in rats by exerting anti-inflammatory and anti-oxidative stress properties. Male Sprague-Dawley rats underwent surgical AAA induction with intraluminal elastase infusion. We compared vehicle rats with rats treated with nicotine (1.25 mg/kg/day), and aneurysm progression was monitored by weekly ultrasound images for 28 days. Nicotine treatment significantly promoted AAA progression (p = 0.031). Additionally, gelatin zymography demonstrated that nicotine significantly reduced pro-matrix metalloproteinase (pro-MMP) 2 (p = 0.029) and MMP9 (p = 0.030) activity in aneurysmal tissue. No significant difference was found in the elastin content or the score of elastin degradation between the groups. Neither infiltrating neutrophils nor macrophages, nor aneurysmal messenger RNA (mRNA) levels of pro- or anti-inflammatory cytokines, differed between the vehicle and nicotine groups. Finally, no difference in mRNA levels of markers for anti-oxidative stress or the vascular smooth muscle cells' contractile phenotype was observed. However, proteomics analyses of non-aneurysmal abdominal aortas revealed that nicotine decreased myristoylated alanine-rich C-kinase substrate and proteins, in ontology terms, inflammatory response and reactive oxygen species, and in contradiction to augmented AAAs. In conclusion, nicotine at a dose of 1.25 mg/kg/day augments AAA expansion in this elastase AAA model. These results do not support the use of low-dose nicotine administration for the prevention of AAA progression.

α7 Nicotinic acetylcholine receptor: a key receptor in the cholinergic anti-inflammatory pathway exerting an antidepressant effect

Depression is a common mental illness, which is related to monoamine neurotransmitters and the dysfunction of the cholinergic, immune, glutamatergic, and neuroendocrine systems. The hypothesis of monoamine neurotransmitters is one of the commonly recognized pathogenic mechanisms of depression; however, the drugs designed based on this hypothesis have not achieved good clinical results. A recent study demonstrated that depression and inflammation were strongly correlated, and the activation of alpha7 nicotinic acetylcholine receptor (α7 nAChR)-mediated cholinergic anti-inflammatory pathway (CAP) in the cholinergic system exhibited good therapeutic effects against depression. Therefore, anti-inflammation might be a potential direction for the treatment of depression. Moreover, it is also necessary to further reveal the key role of inflammation and α7 nAChR in the pathogenesis of depression. This review focused on the correlations between inflammation and depression as well-discussed the crucial role of α7 nAChR in the CAP.

Analgesic potential of transdermal nicotine patch in surgery: a systematic review and meta-analysis of randomised placebo-controlled trials

OBJECTIVES

We aimed (1) to systematically review the efficacy of transdermal nicotine patches (NP) for postoperative analgesia, (2) to establish the current quality of evidence and assist clinical decision-making on the subject, and (3) to identify methodological limitations and the need for more well-designed studies.

MATERIALS AND METHODS

We searched six electronic databases, protocol records, and other sources without date or language restriction until March 2022. To develop the search strategy, we formulated a clinical question by using the PICOD method. Eligibility criteria included randomised placebo-controlled trials on the analgesic potential of NP for surgical procedures. This systematic review followed the PRISMA 2020 statement, and we registered the protocol in PROSPERO (#CRD42020205956).

RESULTS

We included 10 randomised placebo-controlled trials (535 patients). The NP administered before induction of anaesthesia and at beginning of surgery reduced the pain immediately after surgery (-0.38; 95% confidence interval [CI]: -0.73 to -0.02), and 6 h (-0.34; 95% CI: -0.68 to -0.01), 12 h (-0.43; 95% CI: -0.71 to -0.15) and 24 h (-0.35; 95%CI: -0.59 to -0.10) after surgery, compared with the placebo patch (PP) group. Sensitivity testing suggests that opioid use could underestimate NP analgesia. Late demand for the first analgesic and consumption of rescue analgesics tended to be lower in the NP group.

CONCLUSIONS

The current findings suggest, with low certainty of evidence, the analgesic potential of NP for surgical procedures.

CLINICAL RELEVANCE

Perioperative use of NP significantly improved postoperative pain, even when opioids were administered or prescribed. Nevertheless, the clinical relevance should be interpreted with caution, owing to the effect sizes of the summary measures and methodological issues. The analgesic potential of NP as an adjuvant therapy to regulate pain and acute inflammation may offer certain clinical advantages, thus warranting further investigation.

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.

The contribution of ion channels to shaping macrophage behaviour

The expanding roles of macrophages in physiological and pathophysiological mechanisms now include normal tissue homeostasis, tissue repair and regeneration, including neuronal tissue; initiation, progression, and resolution of the inflammatory response and a diverse array of anti-microbial activities. Two hallmarks of macrophage activity which appear to be fundamental to their diverse cellular functionalities are cellular plasticity and phenotypic heterogeneity. Macrophage plasticity allows these cells to take on a broad spectrum of differing cellular phenotypes in response to local and possibly previous encountered environmental signals. Cellular plasticity also contributes to tissue- and stimulus-dependent macrophage heterogeneity, which manifests itself as different macrophage phenotypes being found at different tissue locations and/or after different cell stimuli. Together, plasticity and heterogeneity align macrophage phenotypes to their required local cellular functions and prevent inappropriate activation of the cell, which could lead to pathology. To execute the appropriate function, which must be regulated at the qualitative, quantitative, spatial and temporal levels, macrophages constantly monitor intracellular and extracellular parameters to initiate and control the appropriate cell signaling cascades. The sensors and signaling mechanisms which control macrophages are the focus of a considerable amount of research. Ion channels regulate the flow of ions between cellular membranes and are critical to cell signaling mechanisms in a variety of cellular functions. It is therefore surprising that the role of ion channels in the macrophage biology has been relatively overlooked. In this review we provide a summary of ion channel research in macrophages. We begin by giving a narrative-based explanation of the membrane potential and its importance in cell biology. We then report on research implicating different ion channel families in macrophage functions. Finally, we highlight some areas of ion channel research in macrophages which need to be addressed, future possible developments in this field and therapeutic potential.

Association between smoking, e-cigarette use and severe COVID-19: a cohort study

BACKGROUND

Smoking is a risk factor for most respiratory infections, but it may protect against SARS-CoV-2 infection. The objective was to assess whether smoking and e-cigarette use were associated with severe COVID-19.

METHODS

This cohort ran from 24 January 2020 until 30 April 2020 at the height of the first wave of the SARS-CoV-2 epidemic in England. It comprised 7 869 534 people representative of the population of England with smoking status, demographic factors and diseases recorded by general practitioners in the medical records, which were linked to hospital and death data. The outcomes were COVID-19-associated hospitalization, intensive care unit (ICU) admission and death. The associations between smoking and the outcomes were assessed with Cox proportional hazards models, with sequential adjustment for confounding variables and indirect causal factors (body mass index and smoking-related disease).

RESULTS

Compared with never smokers, people currently smoking were at lower risk of COVID-19 hospitalization, adjusted hazard ratios (HRs) were 0.64 (95% confidence intervals 0.60 to 0.69) for <10 cigarettes/day, 0.49 (0.41 to 0.59) for 10-19 cigarettes/day, and 0.61 (0.49 to 0.74) for ≥20 cigarettes/day. For ICU admission, the corresponding HRs were 0.31 (0.24 to 0.40), 0.15 (0.06 to 0.36), and 0.35 (0.17 to 0.74) and death were: 0.79 (0.70 to 0.89), 0.66 (0.48 to 0.90), and 0.77 (0.54 to 1.09) respectively. Former smokers were at higher risk of severe COVID-19: HRs: 1.07 (1.03 to 1.11) for hospitalization, 1.17 (1.04 to 1.31) for ICU admission, and 1.17 (1.10 to 1.24) for death. All-cause mortality was higher for current smoking than never smoking, HR 1.42 (1.36 to 1.48). Among e-cigarette users, the adjusted HR for e-cigarette use and hospitalization with COVID-19 was 1.06 (0.88 to 1.28), for ICU admission was 1.04 (0.57 to 1.89, and for death was 1.12 (0.81 to 1.55).

CONCLUSIONS

Current smoking was associated with a reduced risk of severe COVID-19 but the association with e-cigarette use was unclear. All-cause mortality remained higher despite this possible reduction in death from COVID-19 during an epidemic of SARS-CoV-2. Findings support investigating possible protective mechanisms of smoking for SARS-CoV-2 infection, including the ongoing trials of nicotine to treat COVID-19.

Manipulation of the inflammatory reflex as a therapeutic strategy

The cholinergic anti-inflammatory pathway is the efferent arm of the inflammatory reflex, a neural circuit through which the CNS can modulate peripheral immune responses. Signals communicated via the vagus and splenic nerves use acetylcholine, produced by Choline acetyltransferase (ChAT)+ T cells, to downregulate the inflammatory actions of macrophages expressing α7 nicotinic receptors. Pre-clinical studies using transgenic animals, cholinergic agonists, vagotomy, and vagus nerve stimulation have demonstrated this pathway's role and therapeutic potential in numerous inflammatory diseases. In this review, we summarize what is understood about the inflammatory reflex. We also demonstrate how pre-clinical findings are being translated into promising clinical trials, and we draw particular attention to innovative bioelectronic methods of harnessing the cholinergic anti-inflammatory pathway for clinical use.

Inflammatory reflex disruption in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China, in late 2019 and caused coronavirus disease 2019 (COVID-19), which is still a global pandemic. In most infected people, SARS-CoV-2 can only cause moderate symptoms, while in other patients, it leads to severe illness and eventually death. Although the main clinical manifestation of COVID-19 is often seen in the lungs, this disease affects almost all body organs. The excessive and prolonged release of inflammatory cytokines that may occur in COVID-19 patients, known as cytokine storms, stimulates undesired immune responses and can cause various tissues damage. In the current review article, we focus on the potential advantages of the intrinsic cholinergic anti-inflammatory pathway (CAP) as the efferent arm of inflammatory reflex in COVID-19 management. Considering this endogenous protective mechanism against chronic inflammation, we focused on the effects of SARS-CoV-2 in the destruction of this anti-inflammatory system. Several studies indicated the interaction of SARS-CoV-2 with the alpha7 subtype of the nicotinic acetylcholine receptor as the effector molecule of the inflammatory reflex. On the other hand, neurological manifestations have increasingly been identified as significant extrapulmonary manifestations of COVID-19. The rational connection between these findings and COVID-19 pathogenesis may be an important issue in both our understanding and dealing with this disease. COVID-19 is deeply rooted in our daily life and requires an urgent need for the establishment of effective therapeutic options, and all the possible treatments must be considered for the control of such inflammatory conditions.

Anti-inflammatory activity of Nicotine isolated from Brassica oleracea in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease, associated with chronic inflammation of synoviocytes. TNFα plays a crucial role in the pathogenesis of RA through pro-inflammatory cytokines. Nicotine, an alkaloid used as herbal medicine, often worked as an anti-inflammatory agent. In this study, we tried to uncover the anti-inflammatory impact of nicotine against RA. Nicotine was isolated from Brassica oleracea, purified by high profile liquid chromatography (HPLC). In-silico docking was carried out using bioinformatics tools SWISSADME, PASS, and DIGEP-Pred to determine drug likeliness of nicotine. The In-vitro study was performed in Tumor necrosis factor (TNFα) induced SW982 Synoviocytes by qPCR.  mRNA expression of pro-inflammatory cytokines (TNF, IL6, IL1β) and proteins (TRAF2, P50, P65) were analyzed followed by validation of P65 (RELA), pP65, IkBα by western blot analysis. Nicotine compound was extracted from Brassica oleracea and purified by HPLC method (Rt values at 2.67 min). The physicochemical, pharmacokinetic properties and drug-likeliness of nicotine was studied by in-silico analysis. In-vitro studies revealed that nicotine lowers the expression of inflammatory cytokines (TNF, IL6, IL1β) and proteins (TRAF2, P50, P65) at 1 µg/ml in TNFα induced SW982 cells.Nicotine from natural sources (Brassica oleracea) has been found to be an effective anti- inflammatory compound at a low dosage. Thus identified the role of nicotine present in the natural sources as a therapeutic option for RA, may be recommended as remedial drug instead of synthetic drug.

Early life exposure to nicotine modifies lung gene response after elastase-induced emphysema

Background

Chronic obstructive pulmonary disease (COPD) is among the top 5 causes of mortality in the world and can develop as a consequence of genetic and/or environmental factors. Current efforts are focused on identifying early life insults and how these contribute to COPD development. In line with this, our study focuses on the influence of early life nicotine exposure and its potential impact on (a) lung pulmonary functions, and (b) elastase-induced emphysema in adulthood.

Methods

To address this hypothesis, we developed a model of 2 hits, delivered at different time points: mouse pups were first exposed to nicotine/placebo in utero and during lactation, and then subsequently received elastase/placebo at the age of 11 weeks. The effect of nicotine pretreatment and elastase instillation was assessed by (a) measurement of pulmonary function at post-elastase day (ped) 21, and (b) transcriptomic profiling at ped3 and 21, and complementary protein determination. Statistical significance was determined by 3- and 2-way ANOVA for pulmonary functions, and RNAseq results were analyzed using the R project.

Results

We did not observe any impact of nicotine pre- and early post-natal exposure compared to control samples on lung pulmonary functions in adulthood, as measured by FLEXIVENT technology. After elastase instillation, substantial lung damage was detected by x-ray tomography and was accompanied by loss in body weight at ped3 as well as an increase in cell numbers, inflammatory markers in BAL and lung volume at ped21. Lung functions showed a decrease in elastance and an increase in deep inflation volume and pressure volume (pv) loop area in animals with emphysema at ped21. Nicotine had no effect on elastance and deep inflation volume, but did affect the pv loop area in animals with emphysema at ped21. Extensive transcriptomic changes were induced by elastase at ped3 both in the nicotine-pretreated and the control samples, with several pathways common to both groups, such as for cell cycle, DNA adhesion and DNA damage. Nicotine pretreatment affected the number of lymphocytes present in BAL after elastase instillation and some of the complement pathway related proteins, arguing for a slight modification of the immune response, as well as changes related to general body metabolism. The majority of elastase-induced transcriptomic changes detected at ped3 had disappeared at ped21. In addition, transcriptomic profiling singled out a common gene pool that was independently activated by nicotine and elastase.

Conclusions

Our study reports a broad spectrum of transient transcriptomic changes in mouse emphysema and identifies nicotine as influencing the emphysema-associated immune system response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01956-4.

Toxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor inhalation on rheumatoid arthritis

Tobacco combustion exposure worsens rheumatoid arthritis (RA). Non-combustible tobacco devices, as heat-not-burn tobacco (HNBT), are emerging as harm reduction to smokers by releasing nicotine and lower combustible tobacco products. Nevertheless, HNBT toxicity remains unclear. Hence, here we investigated the impacts of the tobacco combustible product (cigarette smoke; CS) or HNBT vapor exposures on antigen-induced arthritis (AIA) in C57BL/6 mice. Animals were exposed to airflow, HNBT vapor, or CS during 1 h/twice a day, under the Health Canada Intense (HCI) smoking regime, between days 14 to 20 after the first immunization. At day 21, 16 h after the last exposures, mice were i.a. challenged and the AIA effects were evaluated 24 h later. CS- or HNBT-exposed mice presented equivalent blood nicotine levels. CS exposure worsened articular symptoms, pulmonary inflammation, and expression of lung metallothioneins. Nevertheless, CS or HNBT exposures reduced lymphoid organs' cellularity, splenocyte proliferation and IL-2 secretion. Additional in vitro CS or HNBT exposures confirmed the harmful effects on splenocytes, which were partially mediated by the activation of nicotine/α7nAchR pathway. Associated, data demonstrate the toxic mechanisms of CS or HNBT inhalation at HCI regime on RA, and highlight that further investigations are fundamental to assure the toxicity of emerging tobacco products on the immune system during specific challenges.

Regulation of acetylcholinesterase during the lipopolysaccharide-induced inflammatory responses in microglial cells

The non-classical function of acetylcholine (ACh) has been reported in neuroinflammation that represents the modulating factor in immune responses via activation of α7 nicotinic acetylcholine receptor (α7 nAChR), i.e., a cholinergic anti-inflammatory pathway (CAP). Acetylcholinesterase (AChE), an enzyme for ACh hydrolysis, has been proposed to have a non-classical function in immune cells. However, the involvement of AChE in neuroinflammation is unclear. Here, cultured BV2 cell, a microglial cell line, and primary microglia from rats were treated with lipopolysaccharide (LPS) to induce inflammation and to explore the regulation of AChE during this process. The expression profiles of AChE, α7 nAChR, and choline acetyltransferase (ChAT) were revealed in BV2 cells. The expression of AChE (G4 form) was induced significantly in LPS-treated BV2 cells: the induction was triggered by NF-κB and cAMP signaling. Moreover, ACh or α7 nAChR agonist suppressed the LPS-induced production of pro-inflammatory cytokines, as well as the phagocytosis of microglia, by activating α7 nAChR and followed by the regulation of NF-κB and CREB signaling. The ACh-induced suppression of inflammation was abolished in AChE overexpressed cells, but did not show a significant change in AChE mutant (enzymatic activity knockout) transfected cells. These results indicate that the neuroinflammation-regulated function of AChE may be mediated by controlling the ACh level in the brain system.

Cholinergic immunomodulation in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic intestinal disorders characterized by dysregulated immune responses to resident microbiota in genetically susceptible hosts. The activation of the cholinergic system has been proposed for the treatment of IBD patients according to its potential anti-inflammatory effect in vivo. The α-7-nicotinic-acetylcholine receptor (α7nAChR) is involved in the inhibition of inflammatory processes, modulating the production of cytokines, suppressing dendritic cells and macrophage activity, leading to the suppression of T cells. In this review, we address the most recent studies and clinical trials concerning cholinergic signaling and its therapeutic potential for inflammatory bowel diseases.

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.

The role of the vagus nerve on dexmedetomidine promoting survival and lung protection in a sepsis model in rats

BACKGROUND

Sepsis often results in acute lung injury (ALI). Dexmedetomidine (Dex) was reported to protect cells and organs due to its direct cellular effects. This study aims to investigate the role of vagus nerves on Dex induced lung protection in lipopolysaccharide (LPS)-induced ALI rats.

METHODS

The bilateral cervical vagus nerve of male Sprague-Dawley rats was sectioned or just exposed as sham surgery. After LPS administration, Dex antagonist yohimbine (YOH) and/or Dex was injected intraperitoneally to rats with or without vagotomy. The severity of ALI was determined with survival curve analysis and lung pathological scores. The plasma concentrations of interleukin 1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), catecholamine and acetylcholine were measured with enzyme-linked immunosorbent assay.

RESULTS

The median survival time of LPS-induced ALI rats was prolonged by Dex (22 h, 95% CI, [24.46, 92.20]) vs. 14 h, 95% CI, [14.60, 89.57] of the LPS control group, P < 0.05), and the ALI score was reduced by Dex (6.5, 95% CI, [5.23, 8.10] vs. 11.5, 95% CI, [10.23, 13.10] in the LPS group, P < 0.01). However, these protective effects were significantly decreased by either YOH administration or vagotomy. Dex decreased LPS-induced IL-1β, TNF-α, and catecholamine but increased acetylcholine in blood serum; these effects of Dex was partially abolished by vagotomy.

CONCLUSIONS

Our data suggested that Dex increased vagal nerve tone that partially contributed to its anti-inflammatory and lung-protective effects. The indirect anti-inflammation and direct cytoprotection of Dex are likely through high vagal nerve tone and α₂-adrenoceptor activation, respectively.

Differential Effects of Electronic Hookah Vaping and Traditional Combustible Hookah Smoking on Oxidation, Inflammation, and Arterial Stiffness

BACKGROUND

Traditional hookah smoking has grown quickly to become a global tobacco epidemic. More recently, electronic hookahs (e-hookahs)-vaped through traditional water pipes-were introduced as healthier alternatives to combustible hookah. With combustible tobacco smoking, oxidative stress, inflammation, and vascular stiffness are key components in the development and progression of atherosclerosis. The comparable effects of hookah are unknown.

RESEARCH QUESTION

What is the differential acute effect of e-hookah vaping vs combustible hookah smoking on oxidation, inflammation, and arterial stiffness?

STUDY DESIGN AND METHODS

In a randomized crossover design study, among a cohort of 17 healthy young adult chronic hookah smokers, we investigated the effect of e-hookah vaping and hookah smoking on measures of conduit arterial stiffness, including carotid-femoral pulse wave velocity (PWV), augmentation index-corrected for heart rate before and after a 30-min exposure session. We assessed a panel of circulating biomarkers indicative of inflammation and oxidants and measured plasma nicotine and exhaled carbon monoxide (CO) levels before and after the sessions.

RESULTS

e-Hookah vaping tended to lead to a larger acute increase in PWV than hookah smoking (mean ± SE: e-hookah, +0.74 ± 0.12 m/s; combustible hookah, +0.57 ± 0.14 m/s [P < .05 for both]), indicative of large artery stiffening. Compared with baseline, only e-hookah vaping induced an acute increase in augmentation index (e-hookah, +5.58 ± 1.54% [P = .004]; combustible hookah, +2.87 ± 2.12% [P = not significant]). These vascular changes were accompanied by elevation of the proinflammatory biomarkers high-sensitivity C-reactive protein, fibrinogen, and tumor necrosis factor α after vaping (all P < .05). No changes in biomarkers of inflammation and oxidants were observed after smoking. Compared with baseline, exhaled CO levels were higher after smoking than after vaping (+36.81 ± 6.70 parts per million vs -0.38 ± 0.22 parts per million; P < .001), whereas plasma nicotine concentrations were comparable (+6.14 ± 1.03 ng/mL vs +5.24 ± 0.96 ng/mL; P = .478).

INTERPRETATION

Although advertised to be "safe," flavored e-hookah vaping exerts injurious effects on the vasculature that are, at least in part, mediated by inflammation.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03690427; URL: www.clinicaltrials.gov.

Mechanisms underlying antidepressant effect of transcutaneous auricular vagus nerve stimulation on CUMS model rats based on hippocampal α7nAchR/NF-κB signal pathway

Background

Stress-induced neuroinflammation was considered to play a critical role in the pathogenesis of depression. Transcutaneous auricular vagus nerve stimulation (taVNS) is a relatively non-invasive alternative treatment for patients suffering from major depressive disorder. The anti-inflammatory signal of vagus nerve is mediated by α7 nicotinic acetylcholine receptor (α7nAchR), and the hippocampus, the region with the most distribution of α7nAchR, regulates emotions. Here, we investigated the role of α7nAchR mediating hippocampal neuroinflammation in taVNS antidepressant effect though homozygous α7nAChR (−/−) gene knockout and α7nAchR antagonist (methyllycaconitine, MLA).

Methods

There were control, model, taVNS, α7nAChR(−/−) + taVNS, hippocampus (Hi) MLA + taVNS and Hi saline + taVNS groups. We used the chronic unpredicted mild stress (CUMS) method to establish depressive model rats for 42 days, excepting control group. After the successful modeling, except the control and model, the rats in the other groups were given taVNS, which was applied through an electroacupuncture apparatus at the auricular concha (2/15 Hz, 2 mA, 30 min/days) for 21 days. Behavioral tests were conducted at baseline, after modeling and after taVNS intervention, including sucrose preference test (SPT), open field test (OFT) and forced swimming test (FST). These tests are widely used to evaluate depression-like behavior in rats. The samples were taken after experiment, the expressions of α7nAchR, NF-κB p65, IL-1β and the morphology of microglia were detected.

Results

Depression-like behavior and hippocampal neuroinflammation in CUMS model rats were manifested by down-regulated expression of α7nAchR, up-regulated expression of NF-κB p65 and IL-1β, and the morphology of microglia was in amoebic-like activated state. TaVNS could significantly reverse the above-mentioned phenomena, but had rare improvement effect for α7nAChR(−/−) rats and Hi MLA rats.

Conclusion

The antidepressant effect of taVNS is related to hippocampal α7nAchR/NF-κB signal pathway.

The Regulation Effect of α7nAChRs and M1AChRs on Inflammation and Immunity in Sepsis

The inflammatory storm in the early stage and immunosuppression in the late stage are responsible for the high mortality rates and multiple organ dysfunction in sepsis. In recent years, studies have found that the body's cholinergic system can spontaneously and dynamically regulate inflammation and immunity in sepsis according to the needs of the body. Firstly, the vagus nerve senses and regulates local or systemic inflammation by means of the Cholinergic Anti-inflammatory Pathway (CAP) and activation of α7-nicotinic acetylcholine receptors (α7nAChRs); thus, α7nAChRs play important roles for the central nervous system (CNS) to modulate peripheral inflammation; secondly, the activation of muscarinic acetylcholine receptors 1 (M1AChRs) in the forebrain can affect the neurons of the Medullary Visceral Zone (MVZ), the core of CAP, to regulate systemic inflammation and immunity. Based on the critical role of these two cholinergic receptor systems in sepsis, it is necessary to collect and analyze the related findings in recent years to provide ideas for further research studies and clinical applications. By consulting the related literature, we draw some conclusions: MVZ is the primary center for the nervous system to regulate inflammation and immunity. It coordinates not only the sympathetic system and vagus system but also the autonomic nervous system and neuroendocrine system to regulate inflammation and immunity; α7nAChRs are widely expressed in immune cells, neurons, and muscle cells; the activation of α7nAChRs can suppress local and systemic inflammation; the expression of α7nAChRs represents the acute or chronic inflammatory state to a certain extent; M1AChRs are mainly expressed in the advanced centers of the brain and regulate systemic inflammation; neuroinflammation of the MVZ, hypothalamus, and forebrain induced by sepsis not only leads to their dysfunctions but also underlies the regulatory dysfunction on systemic inflammation and immunity. Correcting the neuroinflammation of these regulatory centers and adjusting the function of α7nAChRs and M1AChRs may be two key strategies for the treatment of sepsis in the future.

Inflammatory response of the peripheral neuroendocrine system following downhill running

Exploring the relationship between exercise inflammation and the peripheral neuroendocrine system is essential for understanding how acute or repetitive bouts of exercise can contribute to skeletal muscle adaption. In severe damage, some evidence demonstrates that peripheral neuroendocrine receptors might contribute to inflammatory resolution, supporting the muscle healing process through myogenesis. In this sense, the current study aimed to evaluate two classic peripheral neuronal receptors along with skeletal muscle inflammation and adaptation parameters in triceps brachii after exercise. We euthanized C57BL (10 to 12 weeks old) male mice before, and one, two, and three days after a downhill running protocol. The positive Ly6C cells, along with interleukin-6 (IL-6), nuclear factor kappa B (NF-κB), glucocorticoid receptor (GR), α7 subunits of the nicotinic acetylcholine receptor (nAChRs), and myonuclei accretion were analyzed. Our main results demonstrated that nAChRs increased with the inflammatory and myonuclei accretion responses regardless of NF-κB and GR protein expression. These results indicate that increased nAChR may contribute to skeletal muscle adaption after downhill running in mice.

Varenicline limits ischemia reperfusion injury following testicular torsion in mice

BACKGROUND

Torsion of the spermatic cord and the resulting testicular ischemia leads to the production of inflammatory cytokines and cell death due to impaired aerobic metabolism. Following reperfusion of the testis, a robust innate inflammatory response furthers tissue injury due to the production of reactive oxygen species and disruption of normal capillary function. Blunting the innate immune response with antioxidants, anti-inflammatory medications and targeted genetic interventions reduces long term testicular injury in animal models of torsion, however these approaches have limited clinical applicability. Mediated via α7 nACh receptors, the cholinergic anti-inflammatory pathway limits NFKB signaling and prevents renal fibrosis following warm renal ischemia. We identified varenicline as an FDA approved α7 nAChR agonist and hypothesized that varenicline administration would decrease long-term testicular atrophy and fibrosis in a murine model of testicular torsion.

METHODS

Using an established model, unilateral testicular torsion was induced in mature male CD1 mice by rotating the right testicle 720° for 2 h. In the treatment group, 4 doses of varenicline (1mg/grm) were administered via intraperitoneal injection every 12 h, with the first dose given 1 h after the creation of testicular torsion. The acute inflammatory response was evaluated 48 h following reperfusion of the testis. Long term outcomes were evaluated 30 days following testicular perfusion.

RESULTS

48 h following reperfusion, the testis of animals treated with varenicline demonstrated a significant reduction in the inflammatory response as measured by the acute immune cell infiltrate, myeloperoxidase activity, concentration of reduced glutathione and expression of downstream NF-KB targets. 30 days following reperfusion, animals treated with varenicline, demonstrated decreased testicular atrophy (Summary Figure), fibrosis and expression of pro-fibrotic genes.

CONCLUSION

Activation of a central immunosuppressive cascade with varenicline after the onset of testicular torsion reduces ischemia reperfusion injury and prevents long term testicular atrophy and fibrosis. Further studies are needed to define the optimum dose and varenicline administration regimen. Our results suggest that varenicline offers a novel, FDA approved, adjunct to the current management of testicular torsion.

Retinoic acid attenuates nuclear factor kappaB mediated induction of NLRP3 inflammasome

BACKGROUND

Acetylcholine (ACh), a neurotransmitter and a part of the cholinergic system, can modify immune responses. Expression of acetylcholine receptors (AChR) in immune cells, including macrophages, leads to modulation of their function. Inflammasomes are part of the innate immune system and have been linked to a variety of inflammatory diseases. The NLRP3/ASC/caspase-1/IL-1 axis has emerged as a critical signaling pathway in inflammation process initiation. The role of ACh in modulating inflammasomes in macrophages remains relatively under-explored.

METHODS

The effect of AChR agonist carbachol on inflammasome expression was investigated using murine and human macrophages. Cell lysates were assessed by western blot for protein analysis. Immunofluorescence studies were used to study the translocation of p65. The experiments were conducted in the presence of NF-ĸB inhibitor, AChR antagonists, and retinoic acid (RA) to study the role of NF-ĸB, ACh receptors, and RA, respectively.

RESULTS

We found that carbachol increased the expression of NLRP3 inflammasome (NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18). The treated cells also showed an increase in NF-ĸB activation. The effect of carbachol was diminished by NF-ĸB inhibitor and atropine, a mAChR antagonist. The addition of RA also significantly reduced the effect of carbachol on NLRP3 inflammasomes.

CONCLUSIONS

Our current study suggests that carbachol induces NLRP3 inflammasome activation through mAChR and NF-ĸB, and that RA abolishes the inflammatory response. It reveals the potentials of co-administration of RA with cholinergic drugs to prevent inflammatory responses during cholinergic medications.

Nerve-macrophage interactions in cardiovascular disease

The heart is highly innervated by autonomic neurons, and dynamic autonomic regulation of the heart and blood vessels is essential for animals to carry out the normal activities of life. Cardiovascular diseases, including heart failure and myocardial infarction, are often characterized in part by an imbalance in autonomic nervous system activation, with excess sympathetic and diminished parasympathetic activation. Notably, however, this is often accompanied by chronic inflammation within the cardiovascular tissues, which suggests there are interactions between autonomic dysregulation and inflammation. Recent studies have been unraveling the mechanistic links between autonomic nerves and immune cells within cardiovascular disease. The autonomic nervous system and immune system also act in concert to coordinate the actions of multiple organs that not only maintain homeostasis but also likely play key roles in disease-disease interactions, such as cardiorenal syndrome and multimorbidity. In this review, we summarize the physiological and pathological interactions between autonomic nerves and macrophages in the context of cardiovascular disease.

Cholinergic anti-inflammatory pathway and connective tissue diseases

Connective tissue diseases (CTDs) consist of an extensive range of heterogeneous medical conditions, which are caused by immune-mediated chronic inflammation and influences the various connective tissues of the body. They include rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, vasculitis, Sjögren's syndrome, Behcet's disease, and many other autoimmune CTDs. To date, several anti-inflammatory approaches have been developed to reduce the severity of inflammation or its subsequent organ manifestations. As a logical mechanism to harnesses the undesired inflammation, some studies investigated the role of the intrinsic cholinergic anti-inflammatory pathway (CAP) in the modulation of chronic inflammation. Many different experimental and clinical models have been developed to evaluate the therapeutic significance of the CAP in CTDs. On the other hand, an issue that is less emphasized in this regard is the presence of autonomic neuropathy in CTDs, which influences the efficiency of CAP in such clinical settings. This condition occurs during CTDs and is a well-known complication of patients suffering from them. The advantages and limitations of CAP in the control of inflammatory responses and its possible therapeutic benefits in the treatment of CTDs are the main subjects of the current study. Therefore, this narrative review article is provided based on the recent findings of the complicated role of CAP in CTDs which were retrieved by searching Science Direct, PubMed, Google Scholar, and Web of Science. It seems that delineating the complex influences of CAP would be of great interest in designing novel surgical or pharmacological therapeutic strategies for CTDs therapy.

Cynandione A and PHA-543613 inhibit inflammation and stimulate macrophageal IL-10 expression following α7 nAChR activation

Cynandione A, an acetophenone isolated from Cynanchum Wilfordii Radix, attenuates inflammation. The present study aimed to study the mechanisms underlying cynandione A-induced antiinflammation. Treatment with cynandione A and the specific α7 nicotinic acetylcholine receptor (α7 nAChR) agonist PHA-543613 remarkably reduced overexpression of proinflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β in lipopolysaccharide (LPS)-treated RAW264.7 cells and primary peritoneal macrophages, and endotoxemic mice. Both cynandione A and PHA-543613 also stimulated IL-10 expression in naïve and LPS-treated macrophages and endotoxemic mice. Cynandione A- and PHA-543613-inhibited proinflammatory cytokine expression was completely blocked by the α7 nAChR antagonist methyllycaconitine and the IL-10 antibody. The stimulatory effect of cynandione A and PHA-543613 on IL-10 expression were suppressed by methyllycaconitine and knockdown of α7 nAChRs using siRNA/α7 nAChR. Cynandione A significantly stimulated STAT3 phosphorylation, which was attenuated by methyllycaconitine and the IL-10 neutralizing antibody. The STAT3 activation inhibitor NSC74859 also blocked cynandione A-inhibited proinflammatory cytokine expression. Taken together, our results, for the first time, demonstrate that cynandione A and PHA-543613 inhibit inflammation through macrophageal α7 nAChR activation and subsequent IL-10 expression.

Stimulation of α7 Nicotinic Acetylcholine Receptor by Nicotine Suppresses Decidual M1 Macrophage Polarization Against Inflammation in Lipopolysaccharide-Induced Preeclampsia-Like Mouse Model

Changes in decidual macrophage polarization affect local inflammatory microenvironment and lead to adverse pregnancy outcomes. However, the regulatory mechanism of macrophage polarization in preeclampsia (PE) remains unclear. In this study, we found that α7nAChR expression was significantly down-regulated in decidual macrophages in PE patients compared to normal pregnant women, accompanied by a reduced proportion of M2 phenotype and an increased proportion of M1 phenotype; these results suggested that the reduced α7nAChR activity might contribute to changes in the polarization of decidual macrophages. Then, we further investigated the regulatory role of α7nAChR activation by nicotine on decidual macrophage polarization and placental remodeling in the PE-like mouse model. The PE mice were obtained by i.p. injection of 10 µg/kg lipopolysaccharide (LPS) gestational day (GD) 13, and 40 µg/kg LPS daily until GD16. Subcutaneous injection of 1.0 mg/kg nicotine was administrated from GD14 to GD18. Nicotine treatment increased the decreased M2 phenotype and inhibited the increased M1 phenotype in decidua of pregnant mice induced by LPS. The levels of pro-inflammatory cytokines in decidua were higher but the levels of anti-inflammatory cytokines were lower in PE mice compared to the controls, nicotine reversed these changes. The level of choline acetyltransferase (CHAT) was reduced in the LPS-treated group, it was increased following nicotine treatment. Damage of spiral artery remodeling and down-regulation of markers related to trophoblast invasion in placentas were found in PE mice; nicotine improved these pathological structures of placentas. α-bungarotoxin (α-BGT) which is specific antagonist for α7nAChR could abolish the effects of nicotine on decidual macrophage polarization, trophoblast arrangement and vascular structure in placental tissue in PE mice. These results suggest that α7nAChR plays an important regulatory role in maternal-fetal inflammation and placental remodeling in preeclampsia and may provide a theoretical basis for the discovery of new strategies for preeclampsia.

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 Alleviates Inflammation of Dry Eye Diseases by Regulating the α7nAChR/NF-κB Signaling Pathway

Purpose

We tried to investigate whether electroacupuncture (EA) can reduce inflammation of dry eye disease (DED) by regulating α7nAChR and inhibiting the NF-κB signaling pathway.

Methods

Healthy New Zealand white rabbits were treated with scopolamine hydrobromide (Scop) for 21 consecutive days to establish the DED animal model. After 21 days, EA, fluorometholone (Flu), and α7nAChR antagonist (α-BGT) treatments were performed, and the Scop injection was continued until day 35. During treatment, the fluorescence staining of the corneal epithelium and the level of tear flow were observed. The influence of EA on the LG pathology and inflammatory factors ACh, α7nAChR, and NF-κB was detected using the LG histopathology, transmission electron microscopy (TEM), cytokine protein chip technology, enzyme-linked immunosorbent assay (ELISA), and Western blot.

Results

The EA stimulation can reduce the corneal epithelial damage and repair epithelial cell ultrastructure, promote the tear secretion, relieve the LG atrophy and decrease lipid droplet accumulation in LG acinar cell, and reduce the levels of inflammatory cytokines (i.e., IL-1, MIP-1b, TNF-α, and IL-8) in the LG. The protective effect of EA on the inflammation and the ocular surface is similar to the corticosteroid Flu. EA and Flu can upregulate the expression of the α7nAChR and downregulate the expression of NF-κB. The α7nAChR antagonist α-BGT can reverse the protective effect of EA on the LG and the inhibitory effect on the NF-κB pathway and the expression of inflammatory factors but cannot affect the expression of Flu on the NF-κB pathway and inflammatory factors.

Conclusion

These results prove that EA can alleviate DEDs by stimulating the acupoints around the eyes. These beneficial effects are related to the upregulation of α7nAChR and the downregulation of NF-κB in the LG. The protective effect of LG is mediated through the anti-inflammatory pathway mediated by α7nAChR. EA can reduce the NF-κB P65 nuclear transcription and reduce inflammatory factors by regulating α7nAChR. This expression indicates that the α7nAChR/NF-κB signaling pathway may serve as a potential therapeutic target for EA to treat DEDs.

Acetylcholinesterase inhibitors targeting the cholinergic anti-inflammatory pathway: a new therapeutic perspective in aging-related disorders

Neuroinflammation and cholinergic dysfunction, leading to cognitive impairment, are hallmarks of aging and neurodegenerative disorders, including Alzheimer's disease (AD). Acetylcholinesterase inhibitors (AChEI), the symptomatic therapy in AD, attenuate and delay the cognitive deficit by enhancing cholinergic synapses. The α7 nicotinic acetylcholine (ACh) receptor has shown a double-edged sword feature, as it binds with high affinity Aβ_1-42, promoting intracellular accumulation and Aβ-induced tau phosphorylation, but also exerts neuroprotection by stimulating anti-apoptotic pathways. Moreover, it mediates peripheral and central anti-inflammatory response, being the effector player of the activation of the cholinergic anti-inflammatory pathway (CAIP), that, by decreasing the release of TNF-α, IL-1β, and IL-6, it may have a role in improving cognition. The finding in preclinical models that, in addition to their major function (choline esterase inhibition) AChEIs have neuroprotective properties mediated via α7nAChR and modulate innate immunity, possibly as a result of the increased availability of acetylcholine activating the CAIP, pave the way for new pharmacological intervention in AD and other neurological disorders that are characterized by neuroinflammation. CHRFAM7A is a human-specific gene acting as a dominant negative inhibitor of α7nAChR function, also suggesting a role in affecting human cognition and memory by altering α7nAChR activities in the central nervous system (CNS). This review will summarize the current knowledge on the cholinergic anti-inflammatory pathway in aging-related disorders, and will argue that the presence of the human-restricted CHRFAM7A gene might play a fundamental role in the regulation of CAIP and in the response to AChEI.

Nicotine: Regulatory roles and mechanisms in atherosclerosis progression

Smoking is an independent risk factor for atherosclerosis. The smoke produced by tobacco burning contains more than 7000 chemicals, among which nicotine is closely related to the occurrence and development of atherosclerosis. Nicotine, a selective cholinergic agonist, accelerates the formation of atherosclerosis by stimulating nicotinic acetylcholine receptors (nAChRs) located in neuronal and non-neuronal tissues. This review introduces the pathogenesis of atherosclerosis and the mechanisms involving nicotine and its receptors. Herein, we focus on the various roles of nicotine in atherosclerosis, such as upregulation of growth factors, inflammation, and the dysfunction of endothelial cells, vascular smooth muscle cells (VSMC) as well as macrophages. In addition, nicotine can stimulate the generation of reactive oxygen species, cause abnormal lipid metabolism, and activate immune cells leading to the onset and progression of atherosclerosis. Exosomes, are currently a research hotspot, due to their important connections with macrophages and the VSMC, and may represent a novel application into future preventive treatment to promote the prevention of smoking-related atherosclerosis. In this review, we will elaborate on the regulatory mechanism of nicotine on atherosclerosis, as well as the effects of interference with nicotine receptors and the use of exosomes to prevent atherosclerosis development.

The Spinal α7-Nicotinic Acetylcholine Receptor Contributes to the Maintenance of Cancer-Induced Bone Pain

Introduction

Cancer-induced bone pain (CIBP) is acknowledged as a multifactorial chronic pain that tortures advanced cancer patients, but existing treatment strategies for CIBP have not been satisfactory yet. Investigators have demonstrated that the activation of α7-nAChRs exerts analgesic effects in some chronic pain models. However, the role of spinal α7-nAChRs in CIBP remains unknown. This study was designed to investigate the role of α7-nAChRs in a well-established CIBP model induced by Walker 256 rat mammary gland carcinoma cells.

Methods

The paw withdrawal threshold (PWT) of the ipsilateral hind paw was measured using von Frey filament. The expressions of spinal α7-nAChRs and NF-κB were measured with Western blotting analysis. Immunofluorescence was employed to detect the expression of α7-nAChRs and co-expressed of α7-nAChRs with NeuN or GFAP or Iba1.

Results

Experiment results showed that the expression of spinal α7-nAChRs was significantly downregulated over time in CIBP rats, and in both CIBP rats and sham rats, most of the α7-nAChRs located in neurons. Behavioral data suggested PNU-282,987, a selective α7-nAChRs agonist, dose-dependently produced analgesic effect and positive allosteric modulator could intensify its effects. Further, repeated administration of PNU-282,987 reversed the expression of α7-nAChRs, inhibited the nuclear factor kappa B (NF-κB) signaling pathway, and attenuates CIBP-induced mechanical allodynia state as well.

Conclusion

These results suggest that the reduced expression of spinal α7-nAChRs contributes to the maintenance of CIBP by upregulating NF-κB expression, which implying a novel pharmacological therapeutic target for the treatment of CIBP.

A Selective α7 Nicotinic Acetylcholine Receptor Agonist, PNU-282987, Attenuates ILC2s Activation and Alternaria-Induced Airway Inflammation

Background

The anti-inflammatory effect of an α7nAChR agonist, PNU-282987, has previously been explored in the context of inflammatory disease. However, the effects of PNU-282987 on type 2 innate lymphoid cells (ILC2s)-mediated allergic airway inflammation has not yet been established.

Aims

To determine the effects of PNU-282987 on the function of ILC2s in the context of IL-33– or Alternaria Alternata (AA)– induced airway inflammation.

Methods

PNU-282987 was administered to mice that received recombinant IL-33 or AA intranasal challenges. Lung histological analysis and flow cytometry were performed to determine airway inflammation and the infiltration and activation of ILC2s. The previously published α7nAChR agonist GTS-21 was employed as a comparable reagent. ILC2s were isolated from murine lung tissue and cultured in vitro in the presence of IL-33, IL-2, and IL-7 with/without either PNU-282987 or GTS-21. The expression of the transcription factors GATA3, IKK, and NF-κB were also determined.

Results

PNU-282987 and GTS-21 significantly reduced goblet cell hyperplasia in the airway, eosinophil infiltration, and ILC2s numbers in BALF, following IL-33 or AA challenge. In vitro IL-33 stimulation of isolated lung ILC2s showed a reduction of GATA3 and Ki67 in response to PNU-282987 or GTS-21 treatments. There was a significant reduction in IKK and NF-κB phosphorylation in the PNU-282987–treated group when compared to the GTS-21–treated ILC2s.

Conclusion

PNU-282987 inhibits ILC2-associated airway inflammation, where its effects were comparable to that of GTS-21.

Biologic and advanced immunomodulating therapeutic options for sarcoidosis: a clinical update

Introduction: Sarcoidosis is a multi-organ disease with a wide range of clinical manifestations and outcomes. A quarter of sarcoidosis patients require long-term treatment for chronic disease. In this group, corticosteroids and cytotoxic agents be insufficient to control diseaseAreas covered: Several biologic agents have been studied for treatment of chronic pulmonary and extra-pulmonary disease. A review of the available literature was performed searching PubMed and an expert opinion regarding specific therapy was developed.Expert opinion: These agents have the potential of treating patients who have progressive disease. Many of these agents have different mechanisms of action, response rates, and toxicity profiles.

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.

Nerves in the Tumor Microenvironment: Origin and Effects

Studies have reported the vital role of nerves in tumorigenesis and cancer progression. Nerves infiltrate the tumor microenvironment thereby enhancing cancer growth and metastasis. Perineural invasion, a process by which cancer cells invade the surrounding nerves, provides an alternative route for metastasis and generation of tumor-related pain. Moreover, central and sympathetic nervous system dysfunctions and psychological stress-induced hormone network disorders may influence the malignant progression of cancer through multiple mechanisms. This reciprocal interaction between nerves and cancer cells provides novel insights into the cellular and molecular bases of tumorigenesis. In addition, they point to the potential utility of anti-neurogenic therapies. This review describes the evolving cross-talk between nerves and cancer cells, thus uncovers potential therapeutic targets for cancer.

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.