Interacting with α 7 nAChR is a new mechanism for AChE to enhance the inflammatory response in macrophages

Investigation of bio-active Amaryllidaceae alkaloidal small molecules as putative SARS-CoV-2 main protease and host TMPRSS2 inhibitors: interpretation by in-silico simulation study

The novel coronavirus disease 2019 (Covid-19) outburst is still threatening global health. This highly contagious viral disease is caused by the infection of SARS-CoV-2 virus. Covid-19 and post-Covid-19 complications induce noteworthy mortality. Potential chemical hits and leads against SARS-CoV-2 for combating Covid-19 are urgently required. In the present study, a virtual-screening protocol was executed on potential Amaryllidaceae alkaloids from a pool of natural compound library against SARS-CoV-2 main protease (Mpro) and transmembrane serine protease (TMPRSS2). For the collected 1016 alkaloids from the curated library, initially, molecular docking using AutoDock Vina (ADV), and thereafter 100 ns molecular-dynamic (MD) simulation has been executed for the best top-ranked binding affinity compounds for both the viral and host proteins. Comprehensive intermolecular-binding interactions profile of Amaryllidaceae alkaloids suggested that phyto-compounds Galantamine, Lycorenine, and Neronine as potent modulators of SARS-CoV-2 Mpro and host TMPRSS2 protein. All atomistic long range 100 ns MD simulation studies of each top ranked complex in triplicates also illustrated strong binding affinity of three compounds towards Mpro and TMPRSS2. Identified compounds might be recommended as prospective anti-viral agents for future drug development selectively targeting the SARS-CoV-2 Mpro or blocking host TMPRSS2 receptor, subjected to pre-clinical and clinical assessment for a better understanding of in-vitro molecular interaction and in-vivo validation.Communicated by Ramaswamy H. Sarma.

Possible Prophylactic Effects of Sulforaphane on LPS-Induced Recognition Memory Impairment Mediated by Regulating Oxidative Stress and Neuroinflammatory Proteins in the Prefrontal Cortex Region of the Brain

BACKGROUND

Alzheimer's disease (AD) presents a significant global health concern, characterized by neurodegeneration and cognitive decline. Neuroinflammation is a crucial factor in AD development and progression, yet effective pharmacotherapy remains elusive. Sulforaphane (SFN), derived from cruciferous vegetables and mainly from broccoli, has shown a promising effect via in vitro and in vivo studies as a potential treatment for AD. This study aims to investigate the possible prophylactic mechanisms of SFN against prefrontal cortex (PFC)-related recognition memory impairment induced by lipopolysaccharide (LPS) administration.

METHODOLOGY

Thirty-six Swiss (SWR/J) mice weighing 18-25 g were divided into three groups (n = 12 per group): a control group (vehicle), an LPS group (0.75 mg/kg of LPS), and an LPS + SFN group (25 mg/kg of SFN). The total duration of the study was 3 weeks, during which mice underwent treatments for the initial 2 weeks, with daily monitoring of body weight and temperature. Behavioral assessments via novel object recognition (NOR) and temporal order recognition (TOR) tasks were conducted in the final week of the study. Inflammatory markers (IL-6 and TNF), antioxidant enzymes (SOD, GSH, and CAT), and pro-oxidant (MDA) level, in addition to acetylcholine esterase (AChE) activity and active (caspase-3) and phosphorylated (AMPK) levels, were evaluated. Further, PFC neuronal degeneration, Aβ content, and microglial activation were also examined using H&E, Congo red staining, and Iba1 immunohistochemistry, respectively.

RESULTS

SFN pretreatment significantly improved recognition memory performance during the NOR and TOR tests. Moreover, SFN was protected from neuroinflammation and oxidative stress as well as neurodegeneration, Aβ accumulation, and microglial hyperactivity.

CONCLUSION

The obtained results suggested that SFN has a potential protective property to mitigate the behavioral and biochemical impairments induced by chronic LPS administration and suggested to be via an AMPK/caspase-3-dependent manner.

Design, synthesis, and biological evaluation of new bis-benzylisoquinoline-based analogues as potential neuromuscular blocking agents

Neuromuscular blocking agents (NMBAs) are widely used in anesthesia for intubation and surgical muscle relaxation. Novel atracurium and mivacurium derivatives were developed, with compounds 18c, 18d, and 29a showing mivacurium-like relaxation at 27.27 nmol/kg, and 15b, 15c, 15e, and 15h having a shorter duration at 272.7 nmol/kg. The structure-activity and configuration-activity relationships of these derivatives and 29a's binding to nicotinic acetylcholine receptors were analyzed through molecular docking. Rabbit trials showed 29a has a shorter duration compared to mivacurium. This suggests that linker properties, ammonium group substituents, and configuration are crucial for NMBA activity and duration, with compound 29a emerging as a potential ultra-short-acting NMBA.

Study on quality difference between Belamcanda chinensis (L.) DC and Iris tectorum Maxim. based on chemical chromatogram analysis, biological activity evaluation and in vivo distribution rule

ETHNOPHARMACOLOGICAL RELEVANCE

Belamcanda chinensis (L.) DC. (BC) and Iris tectorum Maxim. (ITM) have been widely used in recent years due to their remarkable curative effects on sore throat, cough and asthma. but they are often misused due to their similar appearance. A comprehensive comparison of the chemical composition, biological activity, pharmacokinetics and tissue distribution between the two active differential components has not been performed. Differences in their specific effects have not been fully elucidated.

AIM OF THE STUDY

This work aims at differentiating between BC and ITM in terms of appearance, chemical composition, biological activity, pharmacokinetics and tissue distribution.

MATERIALS AND METHODS

In this study, the HPLC-FP method was used to find the differences between the chemical components of BC and ITM. The pharmacological experiments were used to compare the differences in activity, including in vitro anti-inflammatory activity with LPS-induced inflammation model of RAW 264.7 cells, inhibition of AChE activity, and the regulation of isolated small intestinal smooth muscle in mice. The pharmacokinetic and tissue distribution profiles were used to analyze the differences between the two in rats.

RESULTS

The types of isoflavones in BC and ITM are basically the same, but their contents in ITM is much higher than that in BC. At the same doses, the release of TNF-α, NO, IL-1β and IL-6 from RAW 264.7 cells in the ITM group was lower than that of the BC group, and the in vitro anti-inflammatory activity of ITM was stronger than that of BC. Meanwhile, ITM had stronger inhibition ability to inhibit AChE activity than BC. The BC extract exhibited an inhibitory effect on the isolated small intestinal smooth muscle of mice, and the ITM extract showed stimulatory effect at low concentration and inhibitory effect at high concentration. There were significant differences in drug-time profiles, kinetic parameters and tissue distribution.

CONCLUSIONS

There are significant differences in the multidimensional aspects of appearance, chemical composition, biological activity, pharmacokinetics, and tissue distribution between BC and ITM. This study provides a theoretical basis for the quality control, pharmacological efficacy and clinical application of the two herbs.

Cholinergic signaling via the α7 nicotinic acetylcholine receptor regulates the migration of monocyte-derived macrophages during acute inflammation

BACKGROUND

The involvement of the autonomic nervous system in the regulation of inflammation is an emerging concept with significant potential for clinical applications. Recent studies demonstrate that stimulating the vagus nerve activates the cholinergic anti-inflammatory pathway that inhibits pro-inflammatory cytokines and controls inflammation. The α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages plays a key role in mediating cholinergic anti-inflammatory effects through a downstream intracellular mechanism involving inhibition of NF-κB signaling, which results in suppression of pro-inflammatory cytokine production. However, the role of the α7nAChR in the regulation of other aspects of the immune response, including the recruitment of monocytes/macrophages to the site of inflammation remained poorly understood.

RESULTS

We observed an increased mortality in α7nAChR-deficient mice (compared with wild-type controls) in mice with endotoxemia, which was paralleled with a significant reduction in the number of monocyte-derived macrophages in the lungs. Corroborating these results, fluorescently labeled α7nAChR-deficient monocytes adoptively transferred to WT mice showed significantly diminished recruitment to the inflamed tissue. α7nAChR deficiency did not affect monocyte 2D transmigration across an endothelial monolayer, but it significantly decreased the migration of macrophages in a 3D fibrin matrix. In vitro analysis of major adhesive receptors (L-selectin, β1 and β2 integrins) and chemokine receptors (CCR2 and CCR5) revealed reduced expression of integrin αM and αX on α7nAChR-deficient macrophages. Decreased expression of αMβ2 was confirmed on fluorescently labeled, adoptively transferred α7nAChR-deficient macrophages in the lungs of endotoxemic mice, indicating a potential mechanism for α7nAChR-mediated migration.

CONCLUSIONS

We demonstrate a novel role for the α7nAChR in mediating macrophage recruitment to inflamed tissue, which indicates an important new aspect of the cholinergic regulation of immune responses and inflammation.

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.

Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model

Introduction

Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration.

Methods

DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination.

Results

DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology.

Conclusion

Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.

The human acetylcholinesterase C-terminal T30 peptide activates neuronal growth through alpha 7 nicotinic acetylcholine receptors and the mTOR pathway

Acetylcholinesterase (AChE) is a highly conserved enzyme responsible for the regulation of acetylcholine signaling within the brain and periphery. AChE has also been shown to participate in non-enzymatic activity and contribute to cellular development and aging. In particular, enzymatic cleavage of the synaptic AChE isoform, AChE-T, is shown to generate a bioactive T30 peptide that binds to the ⍺7 nicotinic acetylcholine receptor (nAChR) at synapses. Here, we explore intracellular mechanisms of T30 signaling within the human cholinergic neural cell line SH-SY5Y using high performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS/MS). Proteomic analysis of cells exposed to (100 nM) T30 for 3-days reveals significant changes within proteins important for cell growth. Specifically, bioinformatic analysis identifies proteins that converge onto the mammalian target of rapamycin (mTOR) pathway signaling. Functional experiments confirm that T30 regulates neural cell growth via mTOR signaling and ⍺7 nAChR activation. T30 was found promote mTORC1 pro-growth signaling through an increase in phosphorylated elF4E and S6K1, and a decrease in the autophagy LC3B-II protein. These findings are corroborated in hippocampal neurons and show that T30 promotes dendritic arborization. Taken together, our findings define mTOR as a novel pathway activated by T30 interaction with the nAChR and suggest a role for this process in human disease.

Visual evaluation of acetylcholinesterase inhibition by an easy-to-operate assay based on N-doped carbon nanozyme with high stability and oxidase-like activity

Acetylcholinesterase (AChE) is the key enzyme associated with neurotransmission, and thus many drugs have been explored for their inhibitory effect on AChE, such as donepezil for Alzheimer's disease and organophosphorus pesticides (OPs). Compared with clinical trials, in vitro screening bioassays for AChE inhibitors are preferable in terms of operability and cost. Herein, we developed an easy-to-operate nanozyme-based colorimetric assay for the evaluation of AChE inhibitory strength with excellent anti-interference ability and low dependence on professional equipment. The metal-free carbon nanozyme NC900 played an important role in the signal output due to its features of efficient oxidase-like activity, excellent water dispersibility, high stability and low color interference. Employing various AChE-targeted or non-targeted pesticides as examples, the as-proposed assay exhibited excellent distinguishing ability for different chemicals. The higher absorption intensity at 652 nm represents a stronger inhibitory effect, as well as blue color. In addition, this method was used to study the influence of pH on the degradation of prodrugs, and the efficiency of mixed pesticides. This work provides a simple and reliable assay to screen AChE inhibitors, which is promising for the preliminary evaluation of a large number of potential candidates.

Neuroimmune nexus in the pathophysiology and therapy of inflammatory disorders: role of α7 nicotinic acetylcholine receptors

The α7-nicotinic acetylcholine receptor (α7nAChR) is a key protein in the cholinergic anti-inflammatory pathway (CAP) that links the nervous and immune systems. Initially, the pathway was discovered based on the observation that vagal nerve stimulation (VNS) reduced the systemic inflammatory response in septic animals. Subsequent studies form a foundation for the leading hypothesis about the central role of the spleen in CAP activation. VNS evokes noradrenergic stimulation of ACh release from T cells in the spleen, which in turn activates α7nAChRs on the surface of macrophages. α7nAChR-mediated signaling in macrophages reduces inflammatory cytokine secretion and modifies apoptosis, proliferation, and macrophage polarization, eventually reducing the systemic inflammatory response. A protective role of the CAP has been demonstrated in preclinical studies for multiple diseases including sepsis, metabolic disease, cardiovascular diseases, arthritis, Crohn's disease, ulcerative colitis, endometriosis, and potentially COVID-19, sparking interest in using bioelectronic and pharmacological approaches to target α7nAChRs for treating inflammatory conditions in patients. Despite a keen interest, many aspects of the cholinergic pathway are still unknown. α7nAChRs are expressed on many other subsets of immune cells that can affect the development of inflammation differently. There are also other sources of ACh that modify immune cell functions. How the interplay of ACh and α7nAChR on different cells and in various tissues contributes to the anti-inflammatory responses requires additional study. This review provides an update on basic and translational studies of the CAP in inflammatory diseases, the relevant pharmacology of α7nAChR-activated drugs and raises some questions that require further investigation.

In a secondary analysis from a randomised, double-blind placebo-controlled trial Dexmedetomidine blocks cholinergic dysregulation in delirium pathogenesis in patients with major surgery

Dexmedetomidine is an alpha-2 adrenoreceptor agonist with anti-inflammatory and anti-delirogenic properties. Pathogenesis of postoperative delirium (POD) includes cholinergic dysfunction and deregulated inflammatory response to surgical trauma. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are discussed as biomarkers for both POD and severity in acute inflammation. To show whether there is a link between blood cholinesterase activities and dexmedetomidine, we performed a secondary analysis of a randomised, double-blind, placebo-controlled trial that recently showed a lower incidence of POD in the dexmedetomidine group. Abdominal or cardiac surgical patients aged ≥ 60 years were randomised to receive dexmedetomidine or placebo intra- and postoperatively in addition to standard general anaesthesia. We analysed the course of perioperative cholinesterase activities of 56 patients, measured preoperatively and twice postoperatively. Dexmedetomidine resulted in no change in AChE activity and caused a rapid recovery of BChE activity after an initial decrease, while placebo showed a significant decrease in both cholinesterase activities. There were no significant between-group differences at any point in time. From these data it can be assumed that dexmedetomidine could alleviate POD via altering the cholinergic anti-inflammatory pathway (CAIP). We advocate for further investigations to show the direct connection between dexmedetomidine and cholinesterase activity.

Anti-inflammatory therapy of atherosclerosis: focusing on IKKβ

Chronic low-grade inflammation has been identified as a major contributor in the development of atherosclerosis. Nuclear Factor-κappa B (NF-κB) is a critical transcription factors family of the inflammatory pathway. As a major catalytic subunit of the IKK complex, IκB kinase β (IKKβ) drives canonical activation of NF-κB and is implicated in the link between inflammation and atherosclerosis, making it a promising therapeutic target. Various natural product derivatives, extracts, and synthetic, show anti-atherogenic potential by inhibiting IKKβ-mediated inflammation. This review focuses on the latest knowledge and current research landscape surrounding anti-atherosclerotic drugs that inhibit IKKβ. There will be more opportunities to fully understand the complex functions of IKKβ in atherogenesis and develop new effective therapies in the future.

Cholinergic dysfunction-induced insufficient activation of alpha7 nicotinic acetylcholine receptor drives the development of rheumatoid arthritis through promoting protein citrullination via the SP3/PAD4 pathway

Both cholinergic dysfunction and protein citrullination are the hallmarks of rheumatoid arthritis (RA), but the relationship between the two phenomena remains unclear. We explored whether and how cholinergic dysfunction accelerates protein citrullination and consequently drives the development of RA. Cholinergic function and protein citrullination levels in patients with RA and collagen-induced arthritis (CIA) mice were collected. In both neuron-macrophage coculture system and CIA mice, the effect of cholinergic dysfunction on protein citrullination and expression of peptidylarginine deiminases (PADs) was assessed by immunofluorescence. The key transcription factors for PAD4 expression were predicted and validated. Cholinergic dysfunction in the patients with RA and CIA mice negatively correlated with the degree of protein citrullination in synovial tissues. The cholinergic or alpha7 nicotinic acetylcholine receptor (α7nAChR) deactivation and activation resulted in the promotion and reduction of protein citrullination in vitro and in vivo, respectively. Especially, the activation deficiency of α7nAChR induced the earlier onset and aggravation of CIA. Furthermore, deactivation of α7nAChR increased the expression of PAD4 and specificity protein-3 (SP3) in vitro and in vivo. Our results suggest that cholinergic dysfunction-induced deficient α7nAChR activation, which induces the expression of SP3 and its downstream molecule PAD4, accelerating protein citrullination and the development of RA.

Mechanism of Action and Structure-Activity Relationship of α-Conotoxin Mr1.1 at the Human α9α10 Nicotinic Acetylcholine Receptor

α-Conotoxins (α-CTxs) can selectively target nicotinic acetylcholine receptors (nAChRs) and are important drug leads for the treatment of cancer, chronic pain, and neuralgia. Here, we chemically synthesized a formerly defined rat α7 nAChR targeting α-CTx Mr1.1 and evaluated its activity at human nAChRs. Mr1.1 was most potent at the human (h) α9α10 nAChR with a half-maximal inhibitory concentration (IC₅₀) of 92.0 nM. Molecular dynamic simulations suggested that Mr1.1 favorably binds at the α10(+)α9(-) and α9(+)α9(-) sites via hydrogen bonds and salt bridges, stabilizing the channel in a closed conformation. Although Mr1.1 and another antagonist, α-CTx Vc1.1 share high sequence similarity and disulfide-bond framework, Mr1.1 has distinct orientations at hα9α10. Based on the Mr1.1-hα9α10 model, analogues were generated, and the more potent Mr1.1[S4Dap], antagonized hα9α10 with an IC₅₀ of 4.0 nM. Furthermore, Mr1.1[S4Dap] displayed analgesic activity in the rat chronic constriction injury (CCI) pain model and therefore presents a promising drug candidate.

Effects of Dangshen Yuanzhi Powder on learning ability and gut microflora in rats with memory disorder

ETHNOPHARMACOLOGICAL RELEVANCE

Yuanzhi Powder is a commonly used traditional Chinese medical formulae for its potency in enhancing memory and learning. In clinical practice, Yuanzhi Powder is a classic formula in TCM to treat amnesia of the type "deficiency of Qi, turbid phlegm harasses the head and eyes, and stagnation of phlegm converting into the fire". Our previous study showed that Yuanzhi Power, used together with Codonopsis Radix (Dangshen Yuanzhi Power, DYP), could improve learning and memory ability in animals with memory disorder (MD) and its efficacy is superior or equivalent to that of the Yuanzhi Power.

AIM OF STUDY

This study aimed to explore the regulatory mechanism of DYP through the "bacteria-gut-brain axis".

MATERIALS AND METHODS

The SD rats were divided randomly into control, model, positive, DYP-L, and DYP-H groups. Except for the control group, the rats were intraperitoneally injected with D-Gal (400 mg/kg) and gavaged with aluminum chloride (200 mg/kg) every day for 50 days. The rats in the DYP group were gavaged with DYP (6.67 and 13.34 g/kg, respectively) from the 15th day, once a day. The rats in the positive group were similarly administrated with piracetam (0.5 g/kg). The rats' bodyweight was recorded from the 16th day. The learning and memory ability of animals was tested by Morris water maze. The levels of MCP-1, NF-L, NSE, and TNF-α in serum were determined by Elisa kit, while the histopathology of duodenum and colon tissues was examined by H & E staining. The diversity of intestinal flora was sequenced and analyzed. In order to reveal the role of intestinal flora in DYP treatment of MD, the intestinal flora composition and the correlation analysis of intestinal flora and the above biochemical indexes were investigated. The intestinal flora function and biological metabolic pathways were predicted and analyzed by the KEGG database.

RESULTS

The MD animals' learning and spatial memory ability decreased significantly, compared with the normal group, accompanied by weight increase and intestinal flora disorder. DYP can improve the learning and memory ability of MD animals, and its efficacy may exert through the following ways: (i) callback the abnormal biochemical indexes of MCP-1, NF-L, NSE, and TNF-α; (ii) decreasing the relative ratio of Firmicutes/Bacteroidetes and repairing the pathology of MD animal intestinal mucosa; and (iii) the regulation of DYP on biochemical blood indexes of MD animals was significantly correlated with the regulation of intestinal flora; (iv) DYP rats showed a strong correlation between cognitive ability improvement and bodyweight loss; (v) besides, DYP could also regulate the metabolic pathways of carbohydrate, amino acid, nucleotide, and energy by affecting related biological functions.

CONCLUSIONS

The results supported that DYP can improve MD animals' learning and memory ability by restoring the intestinal flora disorder and callback the abnormal biochemical indexes in serum, closely related to the "bacteria-gut-brain axis".

Antiatherosclerotic effect of dehydrocorydaline on ApoE-/- mice: inhibition of macrophage inflammation

Despite improvements in cardiovascular disease (CVD) outcomes by cholesterol-lowering statin therapy, the high rate of CVD is still a great concern worldwide. Dehydrocorydaline (DHC) is an alkaloidal compound isolated from the traditional Chinese herb Corydalis yanhusuo. Emerging evidence shows that DHC has anti-inflammatory and antithrombotic benefits, but whether DHC exerts any antiatherosclerotic effects remains unclear. Our study revealed that intraperitoneal (i.p.) injection of DHC in apolipoprotein E-deficient (ApoE^-/-) mice not only inhibited atherosclerosis development but also improved aortic compliance and increased plaque stability. In addition, DHC attenuated systemic and vascular inflammation in ApoE^-/- mice. As macrophage inflammation plays an essential role in the pathogenesis of atherosclerosis, we next examined the direct effects of DHC on bone marrow-derived macrophages (BMDMs) in vitro. Our RNA-seq data revealed that DHC dramatically decreased the levels of proinflammatory gene clusters. We verified that DHC significantly downregulated proinflammatory interleukin (IL)-1β and IL-18 mRNA levels in a time- and concentration-dependent manner. Furthermore, DHC decreased lipopolysaccharide (LPS)-induced inflammation in BMDMs, as evidenced by the reduced protein levels of CD80, iNOS, NLRP3, IL-1β, and IL-18. Importantly, DHC attenuated LPS-induced activation of p65 and the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Thus, we conclude that DHC ameliorates atherosclerosis in ApoE^-/- mice by inhibiting inflammation, likely by targeting macrophage p65- and ERK1/2-mediated pathways.

Anti-aging effect of phlorizin on D-galactose-induced aging in mice through antioxidant and anti-inflammatory activity, prevention of apoptosis, and regulation of the gut microbiota

Aging is an inevitable and complicated process involving many physiological changes. Screening of natural biologically active anti-aging substances is a current research hotspot. Phlorizin (PZ), an important dihydrochalcone phytoconstituent, has been demonstrated to have antioxidant and anti-tumor effects. In this paper, different doses of PZ (20 and 40 mg/kg) were used to research the protective effect on D-galactose (D-gal)-induced aging mice. Following hematoxylin and eosin staining and by observing the hippocampus, we found that PZ alleviated the damage caused by D-gal in neuronal cells, while PZ enhanced the learning and memory abilities of aging mice in a radical eight-arm maze. In order to explain the reasons for these anti-aging effects, we tested the antioxidant enzyme activity and malonic dialdehyde concentration in mouse serum, liver, and brain tissue. The contents of proteins related to anti-inflammation and apoptosis in brain tissue were analyzed, and the gut microbiota was also analyzed. The results indicated that PZ improved antioxidant enzyme activity while significantly reducing the malonic dialdehyde content. Western blotting analysis suggested that PZ effectively alleviated neuro-apoptosis via regulating the expressions of Bax, Bcl-2, and caspase-3. PZ also exerted anti-inflammation effects by regulating the interleukin-1β/inhibitor of nuclear factor kappa B alpha/nuclear factor kappa-light-chain-enhancer of activated B-cells signaling pathways in brain tissues. Importantly, PZ improved the structure and diversity of the gut microbiota, and the microbiota-gut-brain axis may hold a key role in PZ-induced anti-aging effects. In conclusion, PZ can be used as a potential drug candidate to combat aging.

Acrylamide Neurotoxicity as a Possible Factor Responsible for Inflammation in the Cholinergic Nervous System

Acrylamide (ACR) is a chemical compound that exhibits neurotoxic and genotoxic effects. It causes neurological symptoms such as tremors, general weakness, numbness, tingling in the limbs or ataxia. Numerous scientific studies show the effect of ACR on nerve endings and its close connection with the cholinergic system. The cholinergic system is part of the autonomic nervous system that regulates higher cortical functions related to memory, learning, concentration and attention. Within the cholinergic system, there are cholinergic neurons, anatomical cholinergic structures, the neurotransmitter acetylcholine (ACh) and cholinergic receptors. Some scientific reports suggest a negative effect of ACR on the cholinergic system and inflammatory reactions within the body. The aim of the study was to review the current state of knowledge on the influence of acrylamide on the cholinergic system and to evaluate its possible effect on inflammatory processes. The cholinergic anti-inflammatory pathway (CAP) is a neuroimmunomodulatory pathway that is located in the blood and mucous membranes. The role of CAP is to stop the inflammatory response in the appropriate moment. It prevents the synthesis and the release of pro-inflammatory cytokines and ultimately regulates the local and systemic immune response. The cellular molecular mechanism for inhibiting cytokine synthesis is attributed to acetylcholine (ACh), the major vagal neurotransmitter, and the α7 nicotinic receptor (α7nAChR) subunit is a key receptor for the cholinergic anti-inflammatory pathway. The combination of ACh with α7nAChR results in inhibition of the synthesis and release of pro-inflammatory cytokines. The blood AChE is able to terminate the stimulation of the cholinergic anti-inflammatory pathway due to splitting ACh. Accordingly, cytokine production is essential for pathogen protection and tissue repair, but over-release of cytokines can lead to systemic inflammation, organ failure, and death. Inflammatory responses are precisely regulated to effectively protect against harmful stimuli. The central nervous system dynamically interacts with the immune system, modulating inflammation through the humoral and nervous pathways. The stress-induced rise in acetylcholine (ACh) level acts to ease the inflammatory response and restore homeostasis. This signaling process ends when ACh is hydrolyzed by acetylcholinesterase (AChE). There are many scientific reports indicating the harmful effects of ACR on AChE. Most of them indicate that ACR reduces the concentration and activity of AChE. Due to the neurotoxic effect of acrylamide, which is related to the disturbance of the secretion of neurotransmitters, and its influence on the disturbance of acetylcholinesterase activity, it can be concluded that it disturbs the normal inflammatory response.

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.

Phenothiazines as dual inhibitors of SARS-CoV-2 main protease and COVID-19 inflammation

COVID-19, caused by the severe acute respiratory coronavirus 2 (SARS-CoV-2), currently has no treatment for acute infection. The main protease (Mpro) of SARS-CoV-2 is an essential enzyme for viral replication and an attractive target for disease intervention. The phenothiazine moiety has demonstrated drug versatility for biological systems, including inhibition of butyrylcholinesterase, a property important in the cholinesterase anti-inflammatory cascade. Nineteen phenothiazine drugs were investigated using in silico modelling techniques to predict binding energies and inhibition constants (Ki values) with SARS-CoV-2 Mpro. Because most side-effects of phenothiazines are due to interactions with various neurotransmitter receptors and transporters, phenothiazines with few such interactions were also investigated. All compounds were found to bind to the active site of SARS-CoV-2 Mpro and showed Ki values ranging from 1.30 to 52.4 µM in a rigid active site. Nine phenothiazines showed inhibition constants <10 µM. The compounds with limited interactions with neurotransmitter receptors and transporters showed micromolar (µM) Ki values. Docking results were compared with remdesivir and showed similar interactions with key residues Glu-166 and Gln-189 in the active site. This work has identified several phenothiazines with limited neurotransmitter receptor and transporter interactions and that may provide the dual action of inhibiting SARS-CoV-2 Mpro to prevent viral replication and promote the release of anti-inflammatory cytokines to curb viral-induced inflammation. These compounds are promising candidates for further investigation against SARS-CoV-2.

Donepezil Regulates LPS and Aβ-Stimulated Neuroinflammation through MAPK/NLRP3 Inflammasome/STAT3 Signaling

The acetylcholinesterase inhibitors donepezil and rivastigmine have been used as therapeutic drugs for Alzheimer's disease (AD), but their effects on LPS- and Aβ-induced neuroinflammatory responses and the underlying molecular pathways have not been studied in detail in vitro and in vivo. In the present study, we found that 10 or 50 μM donepezil significantly decreased the LPS-induced increases in the mRNA levels of a number of proinflammatory cytokines in BV2 microglial cells, whereas 50 μM rivastigmine significantly diminished only LPS-stimulated IL-6 mRNA levels. In subsequent experiments in primary astrocytes, donepezil suppressed only LPS-stimulated iNOS mRNA levels. To identify the molecular mechanisms by which donepezil regulates LPS-induced neuroinflammation, we examined whether donepezil alters LPS-stimulated proinflammatory responses by modulating LPS-induced downstream signaling and the NLRP3 inflammasome. Importantly, we found that donepezil suppressed LPS-induced AKT/MAPK signaling, the NLRP3 inflammasome, and transcription factor NF-kB/STAT3 phosphorylation to reduce neuroinflammatory responses. In LPS-treated wild-type mice, a model of neuroinflammatory disease, donepezil significantly attenuated LPS-induced microglial activation, microglial density/morphology, and proinflammatory cytokine COX-2 and IL-6 levels. In a mouse model of AD (5xFAD mice), donepezil significantly reduced Aβ-induced microglial and astrocytic activation, density, and morphology. Taken together, our findings indicate that donepezil significantly downregulates LPS- and Aβ-evoked neuroinflammatory responses in vitro and in vivo and may be a therapeutic agent for neuroinflammation-associated diseases such as AD.

Tacrine Induces Endoplasmic Reticulum-Stressed Apoptosis via Disrupting the Proper Assembly of Oligomeric Acetylcholinesterase in Cultured Neuronal Cells

Acetylcholinesterase inhibitors (AChEIs), the most developed treatment strategies for Alzheimer's disease (AD), will be used in clinic for, at least, the next decades. Their side effects are in highly variable from drug to drug with mechanisms remaining to be fully established. The withdrawal of tacrine (Cognex) in the market makes it as an interesting case study. Here, we found tacrine could disrupt the proper trafficking of proline-rich membrane anchor-linked tetrameric acetylcholinesterase (AChE) in the endoplasmic reticulum (ER). The exposure of tacrine in cells expressing AChE, e.g., neurons, caused an accumulation of the misfolded AChE in the ER. This misfolded enzyme was not able to transport to the Golgi/plasma membrane, which subsequently induced ER stress and its downstream signaling cascade of unfolded protein response. Once the stress was overwhelming, the cooperation of ER with mitochondria increased the loss of mitochondrial membrane potential. Eventually, the tacrine-exposed cells lost homeostasis and underwent apoptosis. The ER stress and apoptosis, induced by tacrine, were proportional to the amount of AChE. Other AChEIs (rivastigmine, bis(3)-cognitin, daurisoline, and dauricine) could cause the same problem as tacrine by inducing ER stress in neuronal cells. The results provide guidance for the drug design and discovery of AChEIs for AD treatment. SIGNIFICANCE STATEMENT: Acetylcholinesterase inhibitors (AChEIs) are the most developed treatment strategies for Alzheimer's disease (AD) and will be used in clinic for at least the next decades. This study reports that tacrine and other AChEIs disrupt the proper trafficking of acetylcholinesterase in the endoplasmic reticulum. Eventually, the apoptosis of neurons and other cells are induced. The results provide guidance for drug design and discovery of AChEIs for AD treatment.

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

The multiple biological roles of the cholinesterases

It is tacitly assumed that the biological role of acetylcholinesterase is termination of synaptic transmission at cholinergic synapses. However, together with its structural homolog, butyrylcholinesterase, it is widely distributed both within and outside the nervous system, and, in many cases, the role of both enzymes remains obscure. The transient appearance of the cholinesterases in embryonic tissues is especially enigmatic. The two enzymes' extra-synaptic roles, which are known as 'non-classical' roles, are the topic of this review. Strong evidence has been presented that AChE and BChE play morphogenetic roles in a variety of eukaryotic systems, and they do so either by acting as adhesion proteins, or as trophic factors. As trophic factors, one mode of action is to directly regulate morphogenesis, such as neurite outgrowth, by poorly understood mechanisms. The other mode is by regulating levels of acetylcholine, which acts as the direct trophic factor. Alternate substrates have been sought for the cholinesterases. Quite recently, it was shown that levels of the aggression hormone, ghrelin, which also controls appetite, are regulated by butyrylcholinesterase. The rapid hydrolysis of acetylcholine by acetylcholinesterase generates high local proton concentrations. The possible biophysical and biological consequences of this effect are discussed. The biological significance of the acetylcholinesterases secreted by parasitic nematodes is reviewed, and, finally, the involvement of acetylcholinesterase in apoptosis is considered.