The Effect of α7nAChR Signaling on T Cells and Macrophages and Their Clinical Implication in the Treatment of Rheumatic Diseases

Osthole Activates the Cholinergic Anti-Inflammatory Pathway via α7nAChR Upregulation to Alleviate Inflammatory Responses

Osthole (also known as Osthol) is the main anti-inflammatory coumarin found in Cnidium monnieri and severs as the exclusive quality-controlled component according the Chinese Pharmacopoeia. However, its underlying anti-inflammatory mechanism remains unknown. In this study, we demonstrated that Osthole treatment significantly inhibited the generation of TNF-α, but not IL-6 in the classical LPS-stimulated RAW264.7 macrophage model. In addition, LPS induced the activation of both MAPK and NF-κB signalling pathways, of which the former was dose-dependently restrained by Osthole via suppressing the phosphorylation of JNK and P38 proteins, while the phosphorylation of IκB and P65 proteins remained unaffected. Interestingly, Osthole dose-dependently up-regulated the expression of the key cholinergic anti-inflammatory pathway regulator α7nAChR, and the TNF-α inhibition effect of Osthole was also significantly alleviated by the treatment of α7nAChR antagonist methylbetaine. These results demonstrate that Osthole may regulate TNF-α by promoting the expression of α7nAChR, thereby activate the vagus nerve-dependent cholinergic anti-inflammatory pathway.

Nicotine regulates abnormal macrophage polarization and trophoblast invasion associated with preterm labor via the α7nAChR/SIRT1 axis

INTRODUCTION

Preterm birth (PTB) frequently results from the syndrome of preterm labor (PTL). PTL is linked to an atypical maternal inflammatory response, as well as intrauterine inflammation and/or infection. In this study, we explored the mechanisms involved in nicotine-mediated abnormal macrophage polarization and trophoblast invasion associated with PTL.

METHODS

First, THP-1-M0 macrophages were generated by treating the human monocytic leukemia cell line (THP-1) with phorbol 12-myristate 13-acetate for a duration of 24 h. Afterward, nicotine treatment was administered, followed by coculturing with the HTR-8/SVneo trophoblast cell line (HTR-8) at a ratio of 1:1. Next, we transfected sh-α7nAChR and treated THP-1-M0 macrophages and HTR-8 cells with nicotine. In addition, we transfected THP-1-M0 macrophages with sh-NC or sh-SIRT1 or subjected them to 4 nM nicotinamide adenine dinucleotide (NAD) metabolic inhibitor FK866 treatment. Moreover, HTR-8 cells were treated with nicotine, after which THP-1-M0 macrophages were cocultured with HTR-8 cells. Finally, we constructed an in vivo RU486-induced PTL rat model to verify the effect of nicotine and the mechanisms involved.

RESULTS

We found that nicotine affected polarization and α7nAChR expression in HTR-8 cocultured THP-1-M0 macrophages. Knocking down α7nAChR blocked the effect of nicotine on the proliferation and invasion of HTR-8 cells. Furthermore, nicotine activated the α7nAChR/SIRT1 axis to regulate THP-1-M0 macrophage polarization through the cholinergic anti-inflammatory pathway. Additionally, NAD metabolism mediated the role of the α7nAChR/SIRT1 axis in nicotine-induced polarization of HTR-8 cocultured THP-1-M0 macrophages. In vivo experiments demonstrated that nicotine alleviated inflammation in PTL rats, which involved the α7nAChR/SIRT1 axis.

CONCLUSION

Nicotine regulated abnormal macrophage polarization and trophoblast invasion associated with PTL via the α7nAChR/SIRT1 axis.

Ionotropic and metabotropic responses by alpha 7 nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors (nAChRs) belong to a superfamily of cys-loop receptors characterized by the assembly of five subunits into a multi-protein channel complex. Ligand binding to nAChRs activates rapid allosteric transitions of the receptor leading to channel opening and ion flux in neuronal and non-neuronal cell. Thus, while ionotropic properties of nAChRs are well recognized, less is known about ligand-mediated intracellular metabotropic signaling responses. Studies in neural and non-neural cells confirm ionotropic and metabotropic channel responses following ligand binding. In this review we summarize evidence on the existence of ionotropic and metabotropic signaling responses by homopentameric α7 nAChRs in various cell types. We explore how coordinated calcium entry through the ion channel and calcium release from nearby stores gives rise to signaling important for the modulation of cytoskeletal motility and cell growth. Amino acid residues for intracellular protein binding within the α7 nAChR support engagement in metabotropic responses including signaling through heterotrimeric G proteins in neural and immune cells. Understanding the dual properties of ionotropic and metabotropic nAChR responses is essential in advancing drug development for the treatment of various human disease.

Redefining Autoimmune Disorders' Pathoetiology: Implications for Mood and Psychotic Disorders' Association with Neurodegenerative and Classical Autoimmune Disorders

Although previously restricted to a limited number of medical conditions, there is a growing appreciation that 'autoimmune' (or immune-mediated) processes are important aspects of a wide array of diverse medical conditions, including cancers, neurodegenerative diseases and psychiatric disorders. All of these classes of medical conditions are associated with alterations in mitochondrial function across an array of diverse cell types. Accumulating data indicate the presence of the mitochondrial melatonergic pathway in possibly all body cells, with important consequences for pathways crucial in driving CD8⁺ T cell and B-cell 'autoimmune'-linked processes. Melatonin suppression coupled with the upregulation of oxidative stress suppress PTEN-induced kinase 1 (PINK1)/parkin-driven mitophagy, raising the levels of the major histocompatibility complex (MHC)-1, which underpins the chemoattraction of CD8⁺ T cells and the activation of antibody-producing B-cells. Many factors and processes closely associated with autoimmunity, including gut microbiome/permeability, circadian rhythms, aging, the aryl hydrocarbon receptor, brain-derived neurotrophic factor (BDNF) and its receptor tyrosine receptor kinase B (TrkB) all interact with the mitochondrial melatonergic pathway. A number of future research directions and novel treatment implications are indicated for this wide collection of poorly conceptualized and treated medical presentations. It is proposed that the etiology of many 'autoimmune'/'immune-mediated' disorders should be conceptualized as significantly determined by mitochondrial dysregulation, with alterations in the mitochondrial melatonergic pathway being an important aspect of these pathoetiologies.

Cholinergic dysfunction in COVID-19: frantic search and hoping for the best

A novel coronavirus known as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a potential cause of acute respiratory infection called coronavirus disease 2019 (COVID-19). The binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2) induces a series of inflammatory cellular events with cytopathic effects leading to cell injury and hyperinflammation. Severe SARS-CoV-2 infection may lead to dysautonomia and sympathetic storm due to dysfunction of the autonomic nervous system (ANS). Therefore, this review aimed to elucidate the critical role of the cholinergic system (CS) in SARS-CoV-2 infection. The CS forms a multi-faceted network performing diverse functions in the body due to its distribution in the neuronal and non-neuronal cells. Acetylcholine (ACh) acts on two main types of receptors which are nicotinic receptors (NRs) and muscarinic receptors (MRs). NRs induce T cell anergy with impairment of antigen-mediated signal transduction. Nicotine through activation of T cell NRs inhibits the expression and release of the pro-inflammatory cytokines. NRs play important anti-inflammatory effects while MRs promote inflammation by inducing the release of pro-inflammatory cytokines. SARS-CoV-2 infection can affect the morphological and functional stability of CS through the disruption of cholinergic receptors. SARS-CoV-2 spike protein is similar to neurotoxins, which can bind to nicotinic acetylcholine receptors (nAChR) in the ANS and brain. Therefore, cholinergic receptors mainly nAChR and related cholinergic agonists may affect the pathogenesis of SARS-CoV-2 infection. Cholinergic dysfunction in COVID-19 is due to dysregulation of nAChR by SARS-CoV-2 promoting the central sympathetic drive with the development of the sympathetic storm. As well, nAChR activators through interaction with diverse signaling pathways can reduce the risk of inflammatory disorders in COVID-19. In addition, nAChR activators may mitigate endothelial dysfunction (ED), oxidative stress (OS), and associated coagulopathy in COVID-19. Similarly, nAChR activators may improve OS, inflammatory changes, and cytokine storm in COVID-19. Therefore, nAChR activators like varenicline in virtue of its anti-inflammatory and anti-oxidant effects with direct anti-SARS-CoV-2 effect could be effective in the management of COVID-19.

Dehydrozingerone Alleviates Hyperalgesia, Oxidative Stress and Inflammatory Factors in Complete Freund’s Adjuvant-Induced Arthritic Rats

Purpose

Rheumatoid arthritis (RA) is a chronic autoimmune disease with severe inflammatory responses. Dehydrozingerone (DHZ) is a potent bioactive compound found in the rhizomes of Zingiber officinale, and it has been reported as an excellent anti-inflammatory and antioxidant agent. This study evaluated the anti-arthritic effects of DHZ in complete Freund’s adjuvant (CFA)-induced arthritis.

Methods

CFA administered rats were intragastrically treated with DHZ (100 mg/kg) for 28 days, and arthritis severity was assessed via body weight, arthritic score, paw edema and hyperalgesia. Serum inflammation biomarkers, oxidative stress markers, inflammatory cytokines and liver function enzymes were evaluated.

Results

The results indicated that DHZ significantly ameliorated arthritis severity as shown by reduced arthritic score, thymus and spleen indexes, paw circumference, paw withdrawal threshold and latency as well as increased body weight gain. Furthermore, DHZ treatment persuasively reduced serum levels of alkaline phosphatase (ALP), aspartate transaminase (AST), alanine transaminase (ALT), rheumatoid factor (RF), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), interleukin-1β and 6 (IL-1β and IL-6), malondialdehyde (MDA), vascular endothelial growth factor (VEGF) and transforming growth factor β (TGF-β). In addition, DHZ observably increased serum superoxide dismutase (SOD) and glutathione (GSH) levels in treated rats.

Conclusion

These findings suggest that DHZ possesses anti-RA effect properties via modulating the inflammatory responses and oxidative stress.