Auto/paracrine control of inflammatory cytokines by acetylcholine in macrophage-like U937 cells through nicotinic receptors

Serum autoantibodies against α7-nicotinic receptors in subgroups of patients with bipolar disorder or schizophrenia: clinical features and link with peripheral inflammation

There is growing evidence that autoantibodies (AAbs) against proteins expressed in the brain are playing an important role in neurological and psychiatric disorders. Here, we explore the presence and the role of peripheral AAbs to the α7-nicotinic acetylcholine receptor (nAChR) in inflammatory subgroups of psychiatric patients with bipolar disorder (BD) or schizophrenia (SCZ) and healthy controls. We have identified a continuum of AAb levels in serum when employing a novel ELISA technique, with a significant elevation in patients compared to controls. Using unsupervised two-step clustering to stratify all the subjects according to their immuno-inflammatory background, we delineate one subgroup consisting solely of psychiatric patients with severe symptoms, high inflammatory profile, and significantly increased levels of anti-nAChR AAbs. In this context, we have used monoclonal mouse anti-human α7-nAChR antibodies (α7-nAChR-mAbs) and shown that TNF-α release was enhanced upon LPS stimulation in macrophages pre-incubated with α7-nAChR-mAbs compared to the use of an isotype control. These findings provide a basis for further study of circulating nicotinic AAbs, and the inflammatory profile observed in patients with major mood and psychotic disorders.

Cholinergic Polarization of Human Macrophages

Macrophages serve as vital defenders, protecting the body by exhibiting remarkable cellular adaptability in response to invading pathogens and various stimuli. These cells express nicotinic acetylcholine receptors, with the α7-nAChR being extensively studied due to its involvement in activating the cholinergic anti-inflammatory pathway. Activation of this pathway plays a crucial role in suppressing macrophages' production of proinflammatory cytokines, thus mitigating excessive inflammation and maintaining host homeostasis. Macrophage polarization, which occurs in response to specific pathogens or insults, is a process that has received limited attention concerning the activation of the cholinergic anti-inflammatory pathway and the contributions of the α7-nAChR in this context. This review aims to present evidence highlighting how the cholinergic constituents in macrophages, led by the α7-nAChR, facilitate the polarization of macrophages towards anti-inflammatory phenotypes. Additionally, we explore the influence of viral infections on macrophage inflammatory phenotypes, taking into account cholinergic mechanisms. We also review the current understanding of macrophage polarization in response to these infections. Finally, we provide insights into the relatively unexplored partial duplication of the α7-nAChR, known as dup α7, which is emerging as a significant factor in macrophage polarization and inflammation scenarios.

Withaferin A: A potential selective glucocorticoid receptor modulator with anti-inflammatory effect

Glucocorticoids have been widely applied to various clinical treatment, however some serious side effects may occur during the treatment. It is widely known that glucocorticoids produce a marked effect through binding to glucocorticoid receptor (GR). As withaferin A can provide multiple health benefits, this work aims to confirm withaferin A as a potential selective GR modulator with anti-inflammatory effect. Fluorescence polarization assay confirmed that withaferin A could steadily bind to GR with an IC50 value of 203.80 ± 0.36 μM. Meanwhile, glucocorticoid receptor translocation of withaferin A was measured by nuclear fractionation assay. Dual luciferase reporter assay showed that withaferin A did not activate GR transcription. Furthermore, withaferin A decreased the GR-related protein expression with less side effects. The result of molecular docking showed that hydrogen-bonding and hydrophobic interactions contributed to the binding of withaferin A with GR. In addition, the GR-withaferin A complex maintained a stable binding throughout the dynamics simulation process. Enzyme-linked immunosorbent assay showed that withaferin A inhibited the production of cytokines, confirming its anti-inflammatory effect. These findings indicate that withaferin A is a potential selective GR modulator and this work may provide a research basis for developing dietary supplements and nutraceuticals against inflammation.

Nicotinic Acetylcholine Receptor Dysfunction in Addiction and in Some Neurodegenerative and Neuropsychiatric Diseases

The cholinergic system plays an essential role in brain development, physiology, and pathophysiology. Herein, we review how specific alterations in this system, through genetic mutations or abnormal receptor function, can lead to aberrant neural circuitry that triggers disease. The review focuses on the nicotinic acetylcholine receptor (nAChR) and its role in addiction and in neurodegenerative and neuropsychiatric diseases and epilepsy. Cholinergic dysfunction is associated with inflammatory processes mainly through the involvement of α7 nAChRs expressed in brain and in peripheral immune cells. Evidence suggests that these neuroinflammatory processes trigger and aggravate pathological states. We discuss the preclinical evidence demonstrating the therapeutic potential of nAChR ligands in Alzheimer disease, Parkinson disease, schizophrenia spectrum disorders, and in autosomal dominant sleep-related hypermotor epilepsy. PubMed and Google Scholar bibliographic databases were searched with the keywords indicated below.

Endocytic coelomocytes are required for lifespan extension by axenic dietary restriction

A rather peculiar but very potent means of achieving longevity is through axenic dietary restriction (ADR), where animals feed on (semi-)defined culture medium in absence of any other lifeform. The little knowledge we already have on ADR is mainly derived from studies using the model organism Caenorhabditis elegans, where ADR more than doubles organismal lifespan. What is underlying this extreme longevity so far remains enigmatic, as ADR seems distinct from other forms of DR and bypasses well-known longevity factors. We here focus first on CUP-4, a protein present in the coelomocytes, which are endocytic cells with a presumed immune function. Our results show that loss of cup-4 or of the coelomocytes affects ADR-mediated longevity to a similar extent. As the coelomocytes have been suggested to have an immune function, we then investigated different central players of innate immune signalling, but could prove no causal links with axenic lifespan extension. We propose that future research focuses further on the role of the coelomocytes in endocytosis and recycling in the context of longevity.

Neurotransmitters: promising immune modulators in the tumor microenvironment

The tumor microenvironment (TME) is modified by its cellular or acellular components throughout the whole period of tumor development. The dynamic modulation can reprogram tumor initiation, growth, invasion, metastasis, and response to therapies. Hence, the focus of cancer research and intervention has gradually shifted to TME components and their interactions. Accumulated evidence indicates neural and immune factors play a distinct role in modulating TME synergistically. Among the complicated interactions, neurotransmitters, the traditional neural regulators, mediate some crucial regulatory functions. Nevertheless, knowledge of the exact mechanisms is still scarce. Meanwhile, therapies targeting the TME remain unsatisfactory. It holds a great prospect to reveal the molecular mechanism by which the interplay between the nervous and immune systems regulate cancer progression for laying a vivid landscape of tumor development and improving clinical treatment.

Nicotinic acetylcholine receptors: Therapeutic targets for novel ligands to treat pain and inflammation

Nicotinic acetylcholine receptors (nAChRs) have been historically defined as ligand-gated ion channels and function as such in the central and peripheral nervous systems. Recently, however, non-ionic signaling mechanisms via nAChRs have been demonstrated in immune cells. Furthermore, the signaling pathways where nAChRs are expressed can be activated by endogenous ligands other than the canonical agonists acetylcholine and choline. In this review, we discuss the involvement of a subset of nAChRs containing α7, α9, and/or α10 subunits in the modulation of pain and inflammation via the cholinergic anti-inflammatory pathway. Additionally, we review the most recent advances in the development of novel ligands and their potential as therapeutics.

α7- and α9-Containing Nicotinic Acetylcholine Receptors in the Functioning of Immune System and in Pain

Nicotinic acetylcholine receptors (nAChRs) present as many different subtypes in the nervous and immune systems, muscles and on the cells of other organs. In the immune system, inflammation is regulated via the vagus nerve through the activation of the non-neuronal α7 nAChR subtype, affecting the production of cytokines. The analgesic properties of α7 nAChR-selective compounds are mostly based on the activation of the cholinergic anti-inflammatory pathway. The molecular mechanism of neuropathic pain relief mediated by the inhibition of α9-containing nAChRs is not fully understood yet, but the role of immune factors in this process is becoming evident. To obtain appropriate drugs, a search of selective agonists, antagonists and modulators of α7- and α9-containing nAChRs is underway. The naturally occurring three-finger snake α-neurotoxins and mammalian Ly6/uPAR proteins, as well as neurotoxic peptides α-conotoxins, are not only sophisticated tools in research on nAChRs but are also considered as potential medicines. In particular, the inhibition of the α9-containing nAChRs by α-conotoxins may be a pathway to alleviate neuropathic pain. nAChRs are involved in the inflammation processes during AIDS and other viral infections; thus they can also be means used in drug design. In this review, we discuss the role of α7- and α9-containing nAChRs in the immune processes and in pain.

The α9α10 acetylcholine receptor: a non-neuronal nicotinic receptor

Within the superfamily of pentameric ligand-gated ion channels, cholinergic nicotinic receptors (nAChRs) were classically identified to mediate synaptic transmission in the nervous system and the neuromuscular junction. The α9 and α10 nAChR subunits were the last ones to be identified. Surprisingly, they do not fall into the dichotomic neuronal/muscle classification of nAChRs. They assemble into heteropentamers with a well-established function as canonical ion channels in inner ear hair cells, where they mediate central nervous system control of auditory and vestibular sensory processing. The present review includes expression, pharmacological, structure-function, molecular evolution and pathophysiological studies, that define receptors composed from α9 and α10 subunits as distant and distinct members within the nAChR family. Thus, although α9 and α10 were initially included within the neuronal subdivision of nAChR subunits, they form a distinct clade within the phylogeny of nAChRs. Following the classification of nAChR subunits based on their main synaptic site of action, α9 and α10 should receive a name in their own right.

The role of dorsal root ganglia alpha-7 nicotinic acetylcholine receptor in complete Freund's adjuvant-induced chronic inflammatory pain

BACKGROUND

Alpha-7 nicotinic acetylcholine receptor (α7 nAChR) was reported to have a critical role in the regulation of pain sensitivity and neuroinflammation. However, the expression level of α7 nAChR in dorsal root ganglion (DRG) and the underlying neuroinflammatory mechanisms associated with hyperalgesia are still unknown.

METHODS

In the present study, the expression and mechanism of α7 nAChR in chronic inflammatory pain was investigated using a complete Freund's adjuvant (CFA)-induced chronic inflammatory pain model. Subsequently, a series of assays including immunohistochemistry, western blotting, and quantitative real-time polymerase chain reaction (qRT-PCR) were performed.

RESULTS

α7 nAChR was mostly colocalized with NeuN in DRG and upregulated after CFA injection. Microinjection of α7 nAChR siRNA into ipsilateral L4/5 DRGs aggravated the CFA-induced pain hypersensitivity. Intrathecal α7 nAChR agonist GTS-21 attenuated the development of CFA-induced mechanical and temperature-related pain hypersensitivities. In neuronal the SH-SY5Y cell line, the knockdown of α7 nAChRs triggered the upregulation of TRAF6 and NF-κB under CFA-induced inflammatory conditions, while agitation of α7 nAChR suppressed the TRAF6/NF-κB activation. α7 nAChR siRNA also exacerbated the secretion of pro-inflammatory mediators from LPS-induced SH-SY5Y cells. Conversely, α7 nAChR-specific agonist GTS-21 diminished the release of interleukin-1beta (IL-1β), IL-6, IL-8, and tumor necrosis factor-α (TNFα) in SH-SY5Y cells under inflammatory conditions. Mechanistically, the modulation of pain sensitivity and neuroinflammatory action of α7 nAChR may be mediated by the TRAF6/NF-κB signaling pathway.

CONCLUSIONS

The findings of this study suggest that α7 nAChR may be potentially utilized as a therapeutic target for therapeutics of chronic inflammatory pain.

Modulation of preeclampsia by the cholinergic anti-inflammatory pathway: Therapeutic perspectives

The cholinergic anti-inflammatory pathway (CAP) is vital for the orchestration of the immune and inflammatory responses under normal and challenged conditions. Over the past two decades, peripheral and central circuits of CAP have been shown to be critically involved in dampening the inflammatory reaction in a wide array of inflammatory disorders. Additionally, emerging evidence supports a key role for CAP in the regulation of the female reproductive system during gestation as well as in the advent of serious pregnancy-related inflammatory insults such as preeclampsia (PE). Within this framework, the modulatory action of CAP encompasses the perinatal maternal and fetal adverse consequences that surface due to antenatal PE programming. Albeit, a considerable gap still exists in our knowledge of the precise cellular and molecular underpinnings of PE/CAP interaction, which hampered global efforts in safeguarding effective preventive or therapeutic measures against PE complications. Here, we summarize reports in the literature regarding the roles of peripheral and reflex cholinergic neuroinflammatory pathways of nicotinic acetylcholine receptors (nAChRs) in reprogramming PE complications in mothers and their progenies. The possible contributions of α7-nAChRs, cholinesterases, immune cells, adhesion molecules, angiogenesis, and endothelial dysfunction to the interaction have also been reviewed.

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.

Street RABV Induces the Cholinergic Anti-inflammatory Pathway in Human Monocyte-Derived Macrophages by Binding to nAChr α7

Rabies virus (RABV) is able to reach the central nervous system (CNS) without triggering a strong immune response, using multiple mechanisms to evade and suppress the host immune system. After infection via a bite or scratch from a rabid animal, RABV comes into contact with macrophages, which are the first antigen-presenting cells (APCs) that are recruited to the area and play an essential role in the onset of a specific immune response. It is poorly understood how RABV affects macrophages, and if the interaction contributes to the observed immune suppression. This study was undertaken to characterize the interactions between RABV and human monocyte-derived macrophages (MDMs). We showed that street RABV does not replicate in human MDMs. Using a recombinant trimeric RABV glycoprotein (rRABV-tG) we showed binding to the nicotinic acetylcholine receptor alpha 7 (nAChr α7) on MDMs, and confirmed the specificity using the nAChr α7 antagonist alpha-bungarotoxin (α-BTX). We found that this binding induced the cholinergic anti-inflammatory pathway (CAP), characterized by a significant decrease in tumor necrosis factor α (TNF-α) upon LPS challenge. Using confocal microscopy we found that induction of the CAP is associated with significant cytoplasmic retention of nuclear factor κB (NF-κB). Co-cultures of human MDMs exposed to street RABV and autologous T cells further revealed that the observed suppression of MDMs might affect their function as T cell activators as well, as we found a significant decrease in proliferation of CD8+ T cells and an increased production of the anti-inflammatory cytokine IL-10. Lastly, using flow cytometric analysis we observed a significant increase in expression of the M2-c surface marker CD163, hinting that street RABV might be able to affect macrophage polarization. Taken together, these results show that street RABV is capable of inducing an anti-inflammatory state in human macrophages, possibly affecting T cell functioning.

Selenium-Containing Amino Acids Protect Dextran Sulfate Sodium-Induced Colitis via Ameliorating Oxidative Stress and Intestinal Inflammation

Background

Inflammatory bowel disease (IBD) is characterized by chronic relapsing inflammation of the gastrointestinal tract. Oxidative stress plays a pivotal role in the pathogenesis of IBD. Selenium-containing amino acids reportedly have anti-oxidative and anti-inflammatory properties, but it remains unknown if selenium-containing amino acids can be used to treat IBD. This study aimed to investigate the effects of two selenium-containing amino acids - selenocysteine and selenocystine - on oxidative stress and chronic inflammation in a mouse model of dextran sulfate sodium (DSS)-induced IBD.

Methodology

C57BL/6 mice were randomly assigned to the following six groups: control, DSS, DSS+selenocysteine, DSS+selenocystine, DSS+sodium selenite, and DSS+N-acetylcysteine (NAC). IBD was induced by 3% DSS. Pro-inflammatory cytokines [interleukin-1β (IL-1β), monocyte chemotactic protein 1 (MCP-1), IL-6, and tumor necrosis factor-α (TNF-α)] and markers for oxidative and anti-oxidative stress [malondialdehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione peroxidase (GPx)] were measured using immunohistochemical analysis.

Results

Selenocysteine and selenocystine significantly attenuated IBD-related symptoms, including preventing weight loss, decreasing disease activity index (DAI) scores, and increasing colon length. Selenocysteine and selenocystine significantly ameliorated the DSS-induced oxidative stress, as demonstrated by a reduction in ROS and MDA activity and an increase in SOD and GPx activity. IL-1, MCP-1, IL-6, and TNF-α levels were significantly increased in the IBD mice, while treatment with the selenium-containing amino acids significantly reduced the levels of these pro-inflammatory cytokines. In vivo safety analysis showed minimal side effects of the selenium-containing amino acids.

Conclusion

We found that selenocysteine and selenocystine ameliorated DSS-induced IBD via reducing oxidative stress and intestinal inflammation, indicating that selenium-containing amino acids could be a novel therapeutic option for patients with IBD.

The Role of α7nAChR-Mediated Cholinergic Anti-inflammatory Pathway in Immune Cells

Alpha 7 nicotinic acetylcholine receptor (α7nAChR) is widely distributed in the nervous and non-cholinergic immune systems. It is necessary for the cholinergic transmitter to participate in the regulation of inflammatory response and is the key element of cholinergic anti-inflammatory pathway (CAP). Because of the profound impact of CAP on the immune system, α7nAChR is considered as a potential therapeutic target for the treatment of inflammatory diseases. Available evidences confirmed that manipulation of CAP by activating α7nAChR with either endogenous acetylcholine (ACh) or cholinergic agonists can substantially alleviate inflammatory responses both in vivo and in vitro. However, the mechanism through which CAP curbs the excessive pro-inflammatory responses and maintains immune homeostasis is not fully understood. Obtained clues suggest that the crosstalk between CAP and classical inflammatory pathways is the key to elucidate the anti-inflammatory mechanism, and the impacts of CAP activation in α7nAChR-expressing immune cells are the foundation of the immunoregulatory property. In this article, we review and update the knowledge concerning the progresses of α7nAChR-based CAP, including α7nAChR properties, signal transductions, interactions with classic immune pathways, and immunoregulatory functions in different immune cells. Certain critical issues to be addressed are also highlighted. By providing a panoramic view of α7nAChR, the summarized evidences will pave the way for the development of novel anti-inflammatory reagents and strategy and inspire further researches.

Disruption of the cholinergic anti-inflammatory response by R5-tropic HIV-1 protein gp120JRFL

Despite current pharmacological intervention strategies, patients with HIV still suffer from chronic inflammation. The nicotinic acetylcholine receptors (nAChRs) are widely distributed throughout the nervous and immune systems. In macrophages, activation of alpha7-nAChR (α7-nAChR) controls inflammatory processes through the cholinergic anti-inflammatory response (CAR). Given that this innate immune response controls inflammation and α7-nAChR plays a critical role in the regulation of systemic inflammation, we investigated the effects of an R5-tropic HIV soluble component, gp120JRFL, on the CAR functioning. We previously demonstrated that X4-tropic HIV-1 gp120IIIB disrupts the CAR as well as inducing upregulation of the α7-nAChR in vitro in monocyte-derived macrophages (MDMs), which correlates with the upregulation observed in monocytes, T-lymphocytes, and MDMs recovered from HIV-infected people. We demonstrate here using imaging and molecular assays that the R5-tropic HIV-1 glycoprotein gp120JRFL upregulates the α7-nAChR in MDMs dependent on CD4 and/or CCR5 activation. This upregulation was also dependent on MEK1 since its inhibition attenuates the upregulation of α7-nAChR induced by gp120JRFL and was concomitant with an increase in basal calcium levels, which did not result in apoptosis. Moreover, the CAR was determined to be disrupted, since α7-nAChR activation in MDMs did not reduce the production of the proinflammatory cytokines IL-6, GRO-α, or I-309. Furthermore, a partial antagonist of α7-nAChR, bupropion, rescued IL-6 but not GRO-α or I-309 production. Together, these results demonstrate that gp120JRFL disrupts the CAR in MDMs. Other medications targeting the α7-nAChR need to be tested to reactivate the CAR to ameliorate inflammation in HIV-infected subjects.

Targeting the α7 nicotinic acetylcholine receptor-A novel road towards the future treatment of skin diseases

Nicotinic acetylcholine receptors (nAChRs) are members of the superfamily of neurotransmitter-gated ion channels. The natural ligand for nAChRs is the endogenous neurotransmitter acetylcholine. Among the nAChRs is the α7nAChR. It is not only expressed by neural tissues but also in the skin. A number of different resident cutaneous cell types including epidermal keratinocytes, sebocytes and dermal fibroblasts express functional α7nAChR. Moreover, cells of the immune system such as lymphocytes, macrophages and monocytes, playing an important role in skin homeostasis, also express α7nAChR. Translational research focusing on the exploitation of the α7nAChR in dermatology has revealed that this neuroendocrine receptor could be promising target for the treatment of inflammatory skin diseases. For example, α7nAChR agonists can counteract transforming growth factor-β1-mediated responses in dermal fibroblasts, key effector cells in scleroderma. In accordance with this α7nAChR, agonists are effective in both inflammation and non-inflammation-driven models of experimentally induced skin fibrosis. Moreover, α7nAChR agonists can modulate expression of proinflammatory cytokines in epidermal keratinocytes that are crucially involved in the pathogenesis of psoriasis and other inflammatory skin diseases. Finally, the capability of α7nAChR agonists to suppress ultraviolet light A/B-induced responses, for example production of proinflammatory cytokines and oxidative stress, the latter crucially involved in dermal photoageing, points to a potential of such agents in the prevention of extrinsic skin ageing. Therefore, emphasis on translational research targeting the α7nAChR in skin may lead to the development of new treatment and prevention modalities against fibrosclerotic skin diseases, psoriasis vulgaris, atopic dermatitis, acne, photodermatoses and extrinsic skin ageing.

The importance of the neuro-immuno-cutaneous system on human skin equivalent design

The skin is a highly complex organ, responsible for sensation, protection against the environment (pollutants, foreign proteins, infection) and thereby linked to the immune and sensory systems in the neuro-immuno-cutaneous (NIC) system. Cutaneous innervation is a key part of the peripheral nervous system; therefore, the skin should be considered a sensory organ and an important part of the central nervous system, an 'active interface' and the first connection of the body to the outside world. Peripheral nerves are a complex class of neurons within these systems, subsets of functions are conducted, including mechanoreception, nociception and thermoception. Epidermal and dermal cells produce signalling factors (such as cytokines or growth factors), neurites influence skin cells (such as via neuropeptides), and peripheral nerves have a role in both early and late stages of the inflammatory response. One way this is achieved, specifically in the cutaneous system, is through neuropeptide release and signalling, especially via substance P (SP), neuropeptide Y (NPY) and nerve growth factor (NGF). Cutaneous, neuronal and immune cells play a central role in many conditions, including psoriasis, atopic dermatitis, vitiligo, UV-induced immunosuppression, herpes and lymphomas. Therefore, it is critical to understand the connections and interplay between the peripheral nervous system and the skin and immune systems, the NIC system. Relevant in vitro tissue models based on human skin equivalents can be used to gain insight and to address impact across research and clinical needs.

Effect of Central Injection of Neostigmine on the Bacterial Endotoxin Induced Suppression of GnRH/LH Secretion in Ewes during the Follicular Phase of the Estrous Cycle

Induced by a bacterial infection, an immune/inflammatory challenge is a potent negative regulator of the reproduction process in females. The reduction of the synthesis of pro-inflammatory cytokine is considered as an effective strategy in the treatment of inflammatory induced neuroendocrine disorders. Therefore, the effect of direct administration of acetylcholinesterase inhibitor—neostigmine—into the third ventricle of the brain on the gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretions under basal and immune stress conditions was evaluated in this study. In the study, 24 adult, 2-years-old Blackhead ewes during the follicular phase of their estrous cycle were used. Immune stress was induced by the intravenous injection of LPS Escherichia coli in a dose of 400 ng/kg. Animals received an intracerebroventricular injection of neostigmine (1 mg/animal) 0.5 h before LPS/saline treatment. It was shown that central administration of neostigmine might prevent the inflammatory-dependent decrease of GnRH/LH secretion in ewes and it had a stimulatory effect on LH release. This central action of neostigmine is connected with its inhibitory action on local pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)α synthesis in the hypothalamus, which indicates the importance of this mediator in the inhibition of GnRH secretion during acute inflammation.

The Cholinergic Anti-Inflammatory Response and the Role of Macrophages in HIV-Induced Inflammation

Macrophages are phagocytic immune cells that protect the body from foreign invaders and actively support the immune response by releasing anti- and proinflammatory cytokines. A seminal finding revolutionized the way macrophages are seen. The expression of the neuronal alpha7 nicotinic acetylcholine receptor (α7-nAChR) in macrophages led to the establishment of the cholinergic anti-inflammatory response (CAR) in which the activation of this receptor inactivates macrophage production of proinflammatory cytokines. This novel neuroimmune response soon began to emerge as a potential target to counteract inflammation during illness and infection states. Human immunodeficiency virus (HIV)-infected individuals suffer from chronic inflammation that persists even under antiretroviral therapy. Despite the CAR’s importance, few studies involving macrophages have been performed in the HIV field. Evidence demonstrates that monocyte-derived macrophages (MDMs) recovered from HIV-infected individuals are upregulated for α7-nAChR. Moreover, in vitro studies demonstrate that addition of an HIV viral constituent, gp120_IIIB, to uninfected MDMs also upregulates the α7-nAChR. Importantly, contrary to what was expected, activation of upregulated α7-nAChRs in macrophages does not reduce inflammation, suggesting a CAR disruption. Although it is reasonable to consider this receptor as a pharmacological target, additional studies are necessary since its activity seems to differ from that observed in neurons.

Peripheral Inhibitor of AChE, Neostigmine, Prevents the Inflammatory Dependent Suppression of GnRH/LH Secretion during the Follicular Phase of the Estrous Cycle

The study was designed to test the hypothesis that the inhibition of acetylcholinesterase (AChE) activity at the periphery by Neostigmine (0.5 mg/animal) will be sufficient to prevent inflammatory dependent suppression of the gonadotropin-releasing hormone (GnRH)/luteinising hormone (LH) secretion in ewes in the follicular phase of the estrous cycle, and this effect will be comparable with the systemic AChE inhibitor, Donepezil (2.5 mg/animal). An immune/inflammatory challenge was induced by peripheral administration of lipopolysaccharide (LPS; 400 ng/kg). Peripheral treatment with Donepezil and Neostigmine prevented the LPS-induced decrease (P < 0.05) in LHβ gene expression in the anterior pituitary gland (AP) and in LH release. Moreover, Donepezil completely abolished (P < 0.05) the suppressory effect of inflammation on GnRH synthesis in the preoptic area, when pretreatment with Neostigmine reduced (P < 0.05) the decrease in GnRH content in this hypothalamic structure. Moreover, administration of both AChE inhibitors diminished (P < 0.05) the inhibitory effect of LPS treatment on the expression of GnRH receptor in the AP. Our study shows that inflammatory dependent changes in the GnRH/LH secretion may be eliminated or reduced by AChE inhibitors suppressing inflammatory reaction only at the periphery such as Neostigmine, without the need for interfering in the central nervous system.

α9-containing nicotinic acetylcholine receptors and the modulation of pain

Neuropathic pain is a complex and debilitating syndrome for which there are few effective pharmacological treatments. Opioid-based medications are initially effective for acute pain, but tolerance to their analgesic effects quickly develops, and long-term use often leads to physical dependence and addiction. Furthermore, neuropathic pain is generally resistant to non-steroidal anti-inflammatory drugs. Other classes of medications including antidepressants, antiepileptics and voltage-gated calcium channel inhibitors are only partially effective in most patients, may be associated with significant side effects and have few disease-modifying effects on the underlying pathology. Medications that act through new mechanisms of action, and particularly ones that have disease-modifying properties, would be highly desirable. In the last decade, a potential new target for the treatment of neuropathic pain has emerged: the α9-containing nicotinic acetylcholine receptor (nAChR). Recent studies indicate that antagonists of α9-containing nAChRs are analgesic in animal models of neuropathic pain. These nerve injury models include chronic constriction injury, partial sciatic nerve ligation, streptozotocin-induced diabetic neuropathy and chemotherapeutic-induced neuropathy. This review details the history and state of the field regarding the role that α9-containing nAChRs may play in neuropathic pain. An alternative hypothesis that α-conotoxins exert their therapeutic effect through blocking N-type calcium channels via activation of GABA_B receptors is also reviewed. Understanding how antagonists of α9-containing nAChRs exert their therapeutic effects may ultimately result in the development of medications that not only treat but also prevent the development of neuropathic pain states.

LINKED ARTICLES

This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.

Nicotine Mediates CD161a+ Renal Macrophage Infiltration and Premature Hypertension in the Spontaneously Hypertensive Rat

RATIONALE

Renal inflammation contributes to the pathophysiology of hypertension. CD161a+ immune cells are dominant in the (SHR) spontaneously hypertensive rat and expand in response to nicotinic cholinergic activation.

OBJECTIVE

We aimed to phenotype CD161a+ immune cells in prehypertensive SHR after cholinergic activation with nicotine and determine if these cells are involved in renal inflammation and the development of hypertension.

METHODS AND RESULTS

Studies used young SHR and WKY (Wistar-Kyoto) rats. Splenocytes and bone marrow cells were exposed to nicotine ex vivo, and nicotine was infused in vivo. Blood pressures, kidney, serum, and urine were obtained. Flow cytometry, Luminex/ELISA, immunohistochemistry, confocal microscopy, and Western blot were used. Nicotinic cholinergic activation induced proliferation of CD161a+/CD68+ macrophages in SHR-derived splenocytes, their renal infiltration, and premature hypertension in SHR. These changes were associated with increased renal expression of MCP-1 (monocyte chemoattractant protein-1) and VLA-4 (very-late antigen-4). LLT1 (lectin-like transcript 1), the ligand for CD161a, was overexpressed in SHR kidney, whereas vascular cellular and intracellular adhesion molecules were similar to those in WKY. Inflammatory cytokines were elevated in SHR kidney and urine after nicotine infusion. Nicotine-mediated renal macrophage infiltration/inflammation was enhanced in denervated kidneys, not explained by angiotensin II levels or expression of angiotensin type-1/2 receptors. Moreover, expression of the anti-inflammatory α7-nAChR (α7-nicotinic acetylcholine receptor) was similar in young SHR and WKY rats.

CONCLUSIONS

A novel, inherited nicotinic cholinergic inflammatory effect exists in young SHR, measured by expansion of CD161a+/CD68+ macrophages. This leads to renal inflammation and premature hypertension, which may be partially explained by increased renal expression of LLT-1, MCP-1, and VLA-4.

Vesicular acetylcholine transporter knock down-mice are more susceptible to inflammation, c-Fos expression and sickness behavior induced by lipopolysaccharide

In addition to the well-known functions as a neurotransmitter, acetylcholine (ACh) can modulate of the immune system. Nonetheless, how endogenous ACh release inflammatory responses is still not clear. To address this question, we took advantage of an animal model with a decreased ACh release due a reduction (knockdown) in vesicular acetylcholine transporter (VAChT) expression (VAChT-KD(HOM)). These animals were challenged with lipopolysaccharide (LPS). Afterwards, we evaluated sickness behavior and quantified systemic and cerebral inflammation as well as neuronal activation in the dorsal vagal complex (DVC). VAChT-KD(HOM) mice that were injected with LPS (10mg/kg) showed increased mortality rate as compared to control mice. In line with this result, a low dose of LPS (0.1mg/kg) increased the levels of pro-inflammatory (TNF-α, IL-1β, and IL-6) and anti-inflammatory (IL-10) cytokines in the spleen and brain of VAChT-KD(HOM) mice in comparison with controls. Similarly, serum levels of TNF-α and IL-6 were increased in VAChT-KD(HOM) mice. This excessive cytokine production was completely prevented by administration of a nicotinic receptor agonist (0.4mg/kg) prior to the LPS injection. Three hours after the LPS injection, c-Fos expression increased in the DVC region of VAChT-KD(HOM) mice compared to controls. In addition, VAChT-KD(HOM) mice showed behavioral changes such as lowered locomotor and exploratory activity and reduced social interaction after the LPS challenge, when compared to control mice. Taken together, our results show that the decreased ability to release ACh exacerbates systemic and cerebral inflammation and promotes neural activation and behavioral changes induced by LPS. In conclusion, our findings support the notion that activity of cholinergic pathways, which can be modulated by VAChT expression, controls inflammatory and neural responses to LPS challenge.

Antinociceptive and anti-inflammatory effects of a Geissospermum vellosii stem bark fraction

Geissospermum vellosii (Pao pereira) is a Brazilian tree whose stem barks are rich in indole alkaloids that present intense anticholinesterase activity. The present study evaluated the effects of a stem bark fraction (PPAC fraction) and ethanolic extract (EE) of Pao pereira in classic murine models of inflammation and pain. The EE and PPAC fraction, both at a dose of 30 mg/kg, significantly reduced mice abdominal constriction induced by acetic acid by 34.8% and 47.5%, respectively. In the formalin test, EE (30 mg/kg) and PPAC fraction (30 and 60 mg/kg) inhibited only the second phase, by 82.8%, 84.9% and 100%, respectively. Compared with indomethacin, similar doses of EE or PPAC fraction were approximately twice as effective in causing antinociception. PPAC fraction was not effective in the hot plate test but reduced the inflammatory response at the second (50.6%) and third (57.8%) hours of rat paw edema induced by carrageenan. Antihyperalgesic activity was observed within 30 min with a peak at 2 h (60.1%). These results demonstrate that compounds in PPAC fraction have anti-inflammatory and antinociceptive activity by a mechanism apparently unrelated to the opioid system. Regardless of similar responses to indomethacin, the effects of PPAC fraction are mainly attributed to acetylcholine actions.

Phosphocholine-Modified Macromolecules and Canonical Nicotinic Agonists Inhibit ATP-Induced IL-1β Release

IL-1β is a potent proinflammatory cytokine of the innate immune system that is involved in host defense against infection. However, increased production of IL-1β plays a pathogenic role in various inflammatory diseases, such as rheumatoid arthritis, gout, sepsis, stroke, and transplant rejection. To prevent detrimental collateral damage, IL-1β release is tightly controlled and typically requires two consecutive danger signals. LPS from Gram-negative bacteria is a prototypical first signal inducing pro-IL-1β synthesis, whereas extracellular ATP is a typical second signal sensed by the ATP receptor P2X7 that triggers activation of the NLRP3-containing inflammasome, proteolytic cleavage of pro-IL-1β by caspase-1, and release of mature IL-1β. Mechanisms controlling IL-1β release, even in the presence of both danger signals, are needed to protect from collateral damage and are of therapeutic interest. In this article, we show that acetylcholine, choline, phosphocholine, phosphocholine-modified LPS from Haemophilus influenzae, and phosphocholine-modified protein efficiently inhibit ATP-mediated IL-1β release in human and rat monocytes via nicotinic acetylcholine receptors containing subunits α7, α9, and/or α10. Of note, we identify receptors for phosphocholine-modified macromolecules that are synthesized by microbes and eukaryotic parasites and are well-known modulators of the immune system. Our data suggest that an endogenous anti-inflammatory cholinergic control mechanism effectively controls ATP-mediated release of IL-1β and that the same mechanism is used by symbionts and misused by parasites to evade innate immune responses of the host.

Cholinergic anti-inflammatory pathway and gastrointestinal diseases

Upon stimulation, vagus nerves release acetylcholine in local tissues, which can regulate immunecell function and inflammatory responses, operationally through alpha 7 nicotinic acetylcholine receptor. This process is termed cholinergic anti-inflammatory pathway (CAP). It has been shown that CAP exhibits physical functions, and also contributes to the progression of a variety of gastrointestinal diseases, such as inflammatory bowel disease, esophagitis, allergic intestine inflammation, peptic ulcer, colitis, and hepatitis. This review discusses the physical function of CAP, as well as its pivotal role in the development of gastrointestinal diseases.

Mental stress in atopic dermatitis--neuronal plasticity and the cholinergic system are affected in atopic dermatitis and in response to acute experimental mental stress in a randomized controlled pilot study

Rationale

In mouse models for atopic dermatitis (AD) hypothalamus pituitary adrenal axis (HPA) dysfunction and neuropeptide-dependent neurogenic inflammation explain stress-aggravated flares to some extent. Lately, cholinergic signaling has emerged as a link between innate and adaptive immunity as well as stress responses in chronic inflammatory diseases. Here we aim to determine in humans the impact of acute stress on neuro-immune interaction as well as on the non-neuronal cholinergic system (NNCS).

Methods

Skin biopsies were obtained from 22 individuals (AD patients and matched healthy control subjects) before and after the Trier social stress test (TSST). To assess neuro-immune interaction, nerve fiber (NF)-density, NF-mast cell contacts and mast cell activation were determined by immunohistomorphometry. To evaluate NNCS effects, expression of secreted mammal Ly-6/urokinase-type plasminogen activator receptor-related protein (SLURP) 1 and 2 (endogenous nicotinic acetylcholine receptor ligands) and their main corresponding receptors were assessed by quantitative RT-PCR.

Results

With respect to neuro-immune interaction we found higher numbers of NGF+ dermal NF in lesional compared to non-lesional AD but lower numbers of Gap43+ growing NF at baseline. Mast cell-NF contacts correlated with SCORAD and itch in lesional skin. With respect to the NNCS, nicotinic acetylcholine receptor α7 (α7nAChR) mRNA was significantly lower in lesional AD skin at baseline. After TSST, PGP 9.5+ NF numbers dropped in lesional AD as did their contacts with mast cells. NGF+ NF now correlated with SCORAD and mast cell-NF contacts with itch in non-lesional skin. At the same time, SLURP-2 levels increased in lesional AD skin.

Conclusions

In humans chronic inflammatory and highly acute psycho-emotional stress interact to modulate cutaneous neuro-immune communication and NNCS marker expression. These findings may have consequences for understanding and treatment of chronic inflammatory diseases in the future.

The acetylcholine signaling network of corneal epithelium and its role in regulation of random and directional migration of corneal epithelial cells

PURPOSE

Because cholinergic drugs are used in ophthalmology and cholinergic stimulation has been shown to facilitate epithelialization of mucocutaneous wounds, we performed a systematic analysis of components of the cholinergic network of human and murine corneal epithelial cells (CECs) and determined the role of autocrine and paracrine acetylcholine (ACh) in regulation of CEC motility.

METHODS

We investigated the expression of ACh receptors at the mRNA and protein levels in human immortalized CECs, localization of cholinergic molecules in normal and wounded murine cornea, and the effects of cholinergic drugs on CEC directional and random migration in vitro, intercellular adhesion, and expression of integrin αV and E-cadherin.

RESULTS

We demonstrated that corneal epithelium expresses the ACh-synthesizing enzyme choline acetyltransferase, the ACh-degrading enzyme acetylcholinesterase, two muscarinic ACh receptors (mAChRs), M3 and M4, and several nicotinic ACh receptors (nAChRs), including both α7- and α9-made homomeric nAChRs and predominantly the α3β2±α5 subtype of heteromeric nAChRs. Wounding affected the expression patterns of cholinergic molecules in the murine corneal epithelium. Constant stimulation of CECs through both muscarinic and nicotinic signaling pathways was essential for CEC survival and both directional and random migration in vitro. Both α7 and non-α7 nAChRs elicited chemotaxis, with the α7 signaling exhibiting a stronger chemotactic effect. Cholinergic stimulation of CECs upregulated expression of the integrin and cadherin molecules involved in epithelialization. We found synergy between the proepithelialization signals elicited by different ACh receptors expressed in CECs.

CONCLUSIONS

Simultaneous stimulation of mAChRs and nAChRs by ACh may be required to synchronize and balance ionic and metabolic events in a single cell. Localization of these cholinergic enzymes and receptors in murine cornea indicated that the concentration of endogenous ACh and the mode of its signaling differ among corneal epithelial layers. Elucidation of the signaling events elicited upon agonist binding to corneal mAChRs and nAChRs will be crucial for understanding the mechanisms of ACh signaling in CECs, which has salient clinical implications.

Anti-inflammatory effects of the nicotinergic peptides SLURP-1 and SLURP-2 on human intestinal epithelial cells and immunocytes

A search for novel and more efficient therapeutic modalities of inflammatory bowel disease (IBD) is one of the most important tasks of contemporary medicine. The anti-inflammatory action of nicotine in IBD might be therapeutic, but its toxicity due to off-target and nonreceptor effects limited its use and prompted a search for nontoxic nicotinergic drugs. We tested the hypothesis that SLURP-1 and -2—the physiological nicotinergic substances produced by the human intestinal epithelial cells (IEC) and immunocytes—can mimic the anti-inflammatory effects of nicotine. We used human CCL-241 enterocytes, CCL-248 colonocytes, CCRF-CEM T-cells, and U937 macrophages. SLURP-1 diminished the TLR9-dependent secretion of IL-8 by CCL-241, and IFNγ-induced upregulation of ICAM-1 in both IEC types. rSLURP-2 inhibited IL-1β-induced secretion of IL-6 and TLR4- and TLR9-dependent induction of CXCL10 and IL-8, respectively, in CCL-241. rSLURP-1 decreased production of TNFα by T-cells, downregulated IL-1β and IL-6 secretion by macrophages, and moderately upregulated IL-10 production by both types of immunocytes. SLURP-2 downregulated TNFα and IFNγR in T-cells and reduced IL-6 production by macrophages. Combining both SLURPs amplified their anti-inflammatory effects. Learning the pharmacology of SLURP-1 and -2 actions on enterocytes, colonocytes, T cells, and macrophages may help develop novel effective treatments of IBD.

Involvement of the α7-nicotinic acetylcholine receptors in the anti-inflammatory action of the thymulin-related peptide (PAT)

BACKGROUND AND PURPOSE

Peptide analog of thymulin (PAT) has been shown to have anti-hyperalgesic and anti-inflammatory properties in animal models of inflammation. Recent reports suggest that the peripheral cholinergic system has an anti-inflammatory role mediated by α7-nicotinic acetylcholine receptor (α7-nAChR). Our aim is to investigate whether the action of PAT is mediated, via the cholinergic pathway.

EXPERIMENTAL APPROACH

The anti-hyperalgesic and anti-inflammatory action of PAT was assessed in rat models of inflammatory nociceptive hyperactivity (carrageenan and endotoxin) and in a mice air-pouch model for localized inflammation, respectively; the possible attenuation of PAT's effects by pretreatment with the α7-nAchR specific antagonist methyllycaconitine citrate (MLA) was also investigated. In another series of experiments, using two electrode recordings, the effect of PAT on the α7-nAChRs, expressed in Xenopus Oocytes, was also determined.

KEY RESULTS

Administration of PAT reversed inflammatory nociceptive hyperactivity and cold and tactile hyperactivity in rats. This effect was partially or totally prevented by MLA, as assessed by different behavioral pain tests. Treatment with PAT also reduced the alteration of cytokines and NGF levels by carrageenan injection in the mouse air pouch model; this effect was partially antagonized by MLA. Electrophysiological recording demonstrated that PAT significantly potentiated the α7-nAchR expressed in Xenopus Oocytes. These effects were not observed when a control peptide, with a reverse sequence (rPAT), was utilized.

CONCLUSIONS AND IMPLICATIONS

The behavioral and electrophysiological observations described in this report demonstrate that PAT mediates, at least partially, its anti-inflammatory action by potentiating the α7-nAChR. These results indicate that PAT has a potential for new therapeutic applications as anti-inflammatory and analgesic agent.

Auto/paracrine nicotinergic peptides participate in cutaneous stress response to wounding

Restoration of epidermal barrier (epithelialization), is a major component of cutaneous response to stress imposed by wounding. Learning physiologic regulation of epithelialization may lead to novel treatments of chronic wounds. The non-canonical ligands of nicotinic acetylcholine receptors SLURP (secreted mammalian Ly-6/urokinase-type plasminogen activator receptor-related proteins)-1 and -2 are produced by keratinocytes (KCs) and inflammatory cells to augment physiologic responses to non-neuronal acetylcholine, suggesting that they can affect wound epithelialization and inflammation. In this study, recombinant (r)SLURP-1 and -2 exhibited dose dependent effects on migration of cultured KCs, and monoclonal antibodies inactivating auto/paracrine SLURPs in mouse skin delayed wound epithelialization. While effects of rSLURPs on migration were opposite, with rSLURP-1 inhibiting and rSLURP-2 stimulating migration of KCs, each anti-SLURP antibody produced a negative effect on epithelialization in vivo, suggesting their more extensive than regulation of keratinocyte migration involvement in wound repair. Since inflammation plays an important role in stress response to wounding, we measured inflammation biomarkers in wounds treated with anti-SLURP antibodies. Both anti-SLURP-1 and -2 antibodies, or their mixture, caused significant elevation of wound myeloperoxidase, IL-1β, IL-6 and TNFα. Taken together, results of this study demonstrated that SLURP-1 slows crawling locomotion of KCs, and exhibits a strong anti-inflammatory activity in wound tissue. In contrast, SLURP-2 facilitates lateral migration of KCs, but shows a lesser anti-inflammatory capacity. Thus, combined biologic activities of both SLURPs may be required for normal stress response to skin wounding, which favors clinical trial of rSLURP-1 and -2 in wounds that fail to heal.

Elevated IL-17A levels in early stages of bladder cancer regardless of smoking status

Aim: The interrelation between nicotine and IL-17A in bladder cancer (BC) patients was investigated. Methods: IL-17A in the sera of 121 BC patients who smoked nicotine, 80 nonsmoker BC patients, 29 and 30 age- and sex-matched healthy smokers and nonsmokers were also measured. Results: IL-17A was elevated in smoker and nonsmoker BC patients compared with smoker and nonsmoker controls (p = 0.004 and p = 0.004, respectively). The level of IL-17A in BC patients who smoked both water pipes and cigarettes were the highest (4.35±8.57 pg/ml), followed by BC water pipe users only (1.33±3.122 pg/ml) and cigarette smokers only (0.79±2.26 pg/ml, p = 0.001). IL-17A was elevated in lower stages (I and II) compared with higher stages (III and IV) of the disease (p = 0.013). Conclusion: IL-17A levels are elevated in some BC patients. IL-17A is an important factor in the inflammatory process during tumor progression, either as a defense mechanism or as a tumor-promoting factor.

Cholinergic regulation of airway inflammation and remodelling

Acetylcholine is the predominant parasympathetic neurotransmitter in the airways that regulates bronchoconstriction and mucus secretion. Recent findings suggest that acetylcholine regulates additional functions in the airways, including inflammation and remodelling during inflammatory airway diseases. Moreover, it has become apparent that acetylcholine is synthesized by nonneuronal cells and tissues, including inflammatory cells and structural cells. In this paper, we will discuss the regulatory role of acetylcholine in inflammation and remodelling in which we will focus on the role of the airway smooth muscle cell as a target cell for acetylcholine that modulates inflammation and remodelling during respiratory diseases such as asthma and COPD.

Pemphigus autoimmunity: hypotheses and realities

The goal of contemporary research in pemphigus vulgaris and pemphigus foliaceus is to achieve and maintain clinical remission without corticosteroids. Recent advances of knowledge on pemphigus autoimmunity scrutinize old dogmas, resolve controversies, and open novel perspectives for treatment. Elucidation of intimate mechanisms of keratinocyte detachment and death in pemphigus has challenged the monopathogenic explanation of disease immunopathology. Over 50 organ-specific and non-organ-specific antigens can be targeted by pemphigus autoimmunity, including desmosomal cadherins and other adhesion molecules, PERP cholinergic and other cell membrane (CM) receptors, and mitochondrial proteins. The initial insult is sustained by the autoantibodies to the cell membrane receptor antigens triggering the intracellular signaling by Src, epidermal growth factor receptor kinase, protein kinases A and C, phospholipase C, mTOR, p38 MAPK, JNK, other tyrosine kinases, and calmodulin that cause basal cell shrinkage and ripping desmosomes off the CM. Autoantibodies synergize with effectors of apoptotic and oncotic pathways, serine proteases, and inflammatory cytokines to overcome the natural resistance and activate the cell death program in keratinocytes. The process of keratinocyte shrinkage/detachment and death via apoptosis/oncosis has been termed apoptolysis to emphasize that it is triggered by the same signal effectors and mediated by the same cell death enzymes. The natural course of pemphigus has improved due to a substantial progress in developing of the steroid-sparing therapies combining the immunosuppressive and direct anti-acantholytic effects. Further elucidation of the molecular mechanisms mediating immune dysregulation and apoptolysis in pemphigus should improve our understanding of disease pathogenesis and facilitate development of steroid-free treatment of patients.

Cytokine-induced alterations of α7 nicotinic receptor in colonic CD4 T cells mediate dichotomous response to nicotine in murine models of Th1/Th17- versus Th2-mediated colitis

Ulcerative colitis (UC) and Crohn's disease (CD) are two forms of chronic inflammatory bowel disease. CD4 T cells play a central role in the pathogenesis of both diseases. Smoking affects both UC and CD but with opposite effects, ameliorating UC and worsening CD. We hypothesized that the severity of gut inflammation could be modulated through T cell nicotinic acetylcholine receptors (nAChRs) and that the exact clinical outcome would depend on the repertoire of nAChRs on CD4 T cells mediating each form of colitis. We measured clinical and immunologic outcomes of treating BALB/c mice with oxazolone- and trinitrobenzene sulfonic acid (TNBS)-induced colitides by nicotine. Nicotine attenuated oxazolone colitis, which was associated with an increased percentage of colonic regulatory T cells and a reduction of Th17 cells. TCR stimulation of naive CD4(+)CD62L(+) T cells in the presence of nicotine upregulated expression of Foxp3. In marked contrast, nicotine worsened TNBS colitis, and this was associated with increased Th17 cells among colonic CD4 T cells. Nicotine upregulated IL-10 and inhibited IL-17 production, which could be abolished by exogenous IL-12 that also abolished the nicotine-dependent upregulation of regulatory T cells. The dichotomous action of nicotine resulted from the up- and downregulation of anti-inflammatory α7 nAChR on colonic CD4 T cells induced by cytokines characteristic of the inflammatory milieu in oxazolone (IL-4) and TNBS (IL-12) colitis, respectively. These findings help explain the dichotomous effect of smoking in patients with UC and CD, and they underscore the potential for nicotinergic drugs in regulating colonic inflammation.

Neuronal stimulation with 5-hydroxytryptamine 4 receptor induces anti-inflammatory actions via α7nACh receptors on muscularis macrophages associated with postoperative ileus

BACKGROUND

The main symptom of postoperative ileus (POI) is an intestinal motility disorder in which monocytes/macrophages and neutrophils play crucial roles. Prokinetic 5-hydroxytryptamine 4 receptor (5-HT₄R) agonists and dopamine receptor antagonists are potential therapeutic agents for directly ameliorating the motility disorder associated with POI.

AIM

To determine the effects of the 5-HT₄R agonists mosapride citrate (MOS) and CJ-033466 on intestinal smooth muscle contractility relative to immune reactions after POI.

METHODS

Intestinal manipulation (IM) was applied to the rat distal ileum. Both MOS (0.3 and 1 mg/kg, s.c.) and CJ-033466 (1 mg/kg, s.c.) were administered to the animals before and after IM. At 24 h after IM, isolated intestinal smooth muscle contractile activity in vitro, gastrointestinal transit in vivo, inflammatory mediator expression and leucocyte infiltration were measured.

RESULTS

After IM, ileal circular muscle contractility in vitro and gastrointestinal transit in vivo were reduced and the number of macrophages and neutrophils increased in the inflamed muscle layer, resulting in the induction of inflammatory mediators such as interleukin 1 β (IL-1β), IL-6, tumour necrosis factor α (TNFα), monocyte chemoattractant protein 1 (MCP-1) and inducible nitric oxide synthase (iNOS). Both MOS and CJ-033466 significantly attenuated not only the intestinal motility dysfunction but also the leucocyte infiltration and inflammatory mediator expression after IM. The autonomic ganglionic blocker hexamethonium (1 mg/kg, i.p.) and the α7-nicotinic acetylcholine receptor (α7nAChR) antagonist methyl lycaconitine citrate (0.087 mg/kg, i.p.) blocked MOS-mediated ameliorative actions. Immunohistochemically, α7nAChR is expressed by monocytes/macrophages but not by neutrophils in the inflamed intestine.

CONCLUSION

Stimulating the 5-HT₄R accelerates acetyl choline (ACh) release from cholinergic myenteric neurons, which subsequently activates α7nAChR on activated monocytes/macrophages to inhibit their inflammatory reactions in the muscle layer. In addition to their gastroprokinetic action, 5-HT₄R agonists might serve as novel therapeutic agents for POI characterised by anti-inflammatory potency.

Alpha7 nicotinic receptors as novel therapeutic targets for inflammation-based diseases

In recent years the etiopathology of a number of debilitating diseases such as type 2 diabetes, arthritis, atherosclerosis, psoriasis, asthma, cystic fibrosis, sepsis, and ulcerative colitis has increasingly been linked to runaway cytokine-mediated inflammation. Cytokine-based therapeutic agents play a major role in the treatment of these diseases. However, the temporospatial changes in various cytokines are still poorly understood and attempts to date have focused on the inhibition of specific cytokines such as TNF-α. As an alternative approach, a number of preclinical studies have confirmed the therapeutic potential of targeting alpha7 nicotinic acetylcholine receptor-mediated anti-inflammatory effects through modulation of proinflammatory cytokines. This "cholinergic anti-inflammatory pathway" modulates the immune system through cholinergic mechanisms that act on alpha7 receptors expressed on macrophages and immune cells. If the preclinical findings translate into human efficacy this approach could potentially provide new therapies for treating a broad array of intractable diseases and conditions with inflammatory components.

Peristalsis in the junction region of the Drosophila larval midgut is modulated by DH31 expressing enteroendocrine cells

Background

The underlying cellular and molecular mechanisms that coordinate the physiological processes in digestion are complex, cryptic, and involve the integration of multiple cellular and organ systems. In all intestines, peristaltic action of the gut moves food through the various stages of digestion from the anterior end towards the posterior, with the rate of flow dependent on signals, both intrinsic and extrinsic to the gut itself.

Results

We have identified an enteroendocrine cell type that regulates gut motility in the Drosophila melanogaster larval midgut. These cells are located at the junction of the anterior and the acidic portions of the midgut and are a group of enteroendocrine cells that express the peptide hormone Diuretic Hormone 31 in this region of the gut. Using cell ablation and ectopic activation via expression of the Chlamydomonas reinhardtii blue light-activated channelopsin, we demonstrate that these enteroendocrine cells are both necessary and sufficient for the peristalsis in the junction region of the midgut and require the Diuretic Hormone 31 to affect normal peristalsis in this region. Within the same junction region of the midgut, we have also identified morphological features suggesting that this region acts as a valve that regulates the transit of food from the anterior midgut into the acidic portion of the gut.

Conclusions

We have characterized and described a set of enteroendocrine cells called the Midgut Junction DH31 expressing cells that are required for peristaltic movement in the junction region between the anterior portion and acidic region of the larval midgut of Drosophila melanogaster. We have shown that the Midgut Junction DH31 expressing cells are necessary and sufficient for motility and that the peptide hormone DH31 is required for peristalsis in the junction region of the midgut. The Drosophila model system will allow for a further dissection of the digestion process and provide a better understanding of the mechanisms that regulate digestion in all organisms.

Antinociceptive and anti-inflammatory effects of choline in a mouse model of postoperative pain

BACKGROUND

Choline is a dietary supplement that activates alpha7 nicotinic receptors. alpha7 nicotinic activation reduces cytokine production by macrophages and has antinociceptive activity in inflammatory pain models. We hypothesized that systemic administration of choline would reduce the inflammatory response from macrophages and have antinociceptive efficacy in a murine model of postoperative pain.

METHODS

We studied the response of wild-type and alpha7 nicotinic knockout mice to heat and punctate pressure after a model surgical procedure. We investigated the effect of genotype and choline treatment on alpha-bungarotoxin binding to, and their production of tumour necrosis factor (TNF) from, macrophages.

RESULTS

Choline provided moderate antinociception. The ED(50) for choline inhibition of heat-induced allodynia was 1.7 mg kg(-1) h(-1). The ED(50) for punctate pressure threshold was 4.7 mg kg(-1) h(-1) choline. alpha7 nicotinic knockout mice had no change in hypersensitivity to heat or pressure and were significantly different from littermate controls when treated with choline 5 mg kg(-1) h(-1) (P<0.05, 0.01). Choline 100 mM reduced binding of alpha-bungarotoxin to macrophages by 72% and decreased their release of TNF by up to 51 (sd 11)%. There was no difference by genotype in the inhibition of TNF release by choline.

CONCLUSIONS

Systemic choline is a moderately effective analgesic via activation of alpha7 nicotinic acetylcholine receptors. The antinocicepive effect may not be mediated by a reduction of TNF pathway cytokine release from macrophages. Although choline at millimolar concentrations clearly inhibits the release of TNF, this effect is not alpha7 subunit-dependent and occurs at concentrations likely higher than reached systemically in vivo.