Nutraceutical activators of AMPK/Sirt1 axis inhibit viral production and protect neurons from neurodegenerative events triggered during HSV-1 infection

Effect of resveratrol on herpesvirus encephalitis: Evidences for its mechanisms of action

BACKGROUND

Herpes simplex virus type 1 (HSV-1)-induced herpes simplex encephalitis (HSE) has a high mortality rate in clinically immunocompromised patients, while recovered patients often experience neurological sequelae due to neuroinflammation. Nucleoside drugs and nucleoside analogues such as acyclovir and ganciclovir are mainly used in clinical treatment, and the emergence of resistant viral strains makes the development of new anti-herpesvirus encephalitis drugs urgent. Resveratrol is a multifunctional, plant-derived bioactive compound and its antiviral potential is attracting much attention.

PURPOSE

This study aimed to investigate the anti-HSV-1 mechanism of resveratrol in microglial cells and in the HSE mouse model.

METHODS

The antiviral effect of resveratrol on HSV-1 infection was investigated by plaque assay, virus titer, immunofluorescence, Western blot and time-of-addition assay. The influence of resveratrol on stimulator of interferon gene (STING)/Nuclear Factor kappa B (NF-κB) signaling pathway-mediated neuroinflammation was examined by Western blot, RT-qPCR and ELISA. The interaction between resveratrol and STING/heat shock protein 90 beta (HSP90β) was evaluated by molecular modeling, co-immunoprecipitation, and drug affinity responsive target stability assay. The therapeutic effect of resveratrol on HSE was evaluated in the HSE mouse model by analyzing weight loss, neurodegenerative symptoms and histopathological scores.

RESULTS

Resveratrol inhibited the early process of HSV-1 infection, and interfered with the STING/NF-κB signaling pathway to attenuate HSV-1-induced neuroinflammation and microglial M1 polarization, independent of its classical target Sirtuin1. Mechanistically, resveratrol completely bound to Glu515 and Lys491 of HSP90β, thus disrupting the HSP90β-STING interaction and promoting STING degradation. Resveratrol also significantly alleviated viral encephalitis and neuroinflammation caused by HSV-1 in the HSE mouse model.

CONCLUSION

Resveratrol acted as a non-classical HSP90β inhibitor, binding to the STING-HSP90β interaction site to promote STING degradation and attenuate HSV-1-induced encephalitis and neuroinflammation. These findings suggest the alternative strategy of targeting HSP90β and resveratrol-mediated inhibition of HSP90β as a potential antiviral approach.

Immunopathology of herpes simplex virus-associated neuroinflammation: Unveiling the mysteries

The immunopathology of herpes simplex virus (HSV)-associated neuroinflammation is a captivating and intricate field of study within the scientific community. HSV, renowned for its latent infection capability, gives rise to a spectrum of neurological expressions, ranging from mild symptoms to severe encephalitis. The enigmatic interplay between the virus and the host's immune responses profoundly shapes the outcome of these infections. This review delves into the multifaceted immune reactions triggered by HSV within neural tissues, intricately encompassing the interplay between innate and adaptive immunity. Furthermore, this analysis delves into the delicate equilibrium between immune defence and the potential for immunopathology-induced neural damage. It meticulously dissects the roles of diverse immune cells, cytokines, and chemokines, unravelling the intricacies of neuroinflammation modulation and its subsequent effects. By exploring HSV's immune manipulation and exploitation mechanisms, this review endeavours to unveil the enigmas surrounding the immunopathology of HSV-associated neuroinflammation. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of HSV infections.

AMPK protects endothelial cells against HSV-1 replication via inhibition of mTORC1 and ACC1

Herpes simplex virus type 1 (HSV-1) is a widespread contagious pathogen, mostly causing mild symptoms on the mucosal entry side. However, systemic distribution, in particular upon reactivation of the virus in immunocompromised patients, may trigger an innate immune response and induce damage of organs. In these conditions, HSV-1 may infect vascular endothelial cells, but little is known about the regulation of HSV-1 replication and possible defense mechanisms in these cells. The current study addresses the question of whether the host cell protein AMP-activated protein kinase (AMPK), an important metabolic sensor, can control HSV-1 replication in endothelial cells. We show that downregulation of the catalytic subunits AMPKα1 and/or AMPKα2 increased HSV-1 replication as monitored by TCID50 titrations, while a potent AMPK agonist, MK-8722, strongly inhibited it. MK-8722 induced a persistent phosphorylation of the AMPK downstream targets acetyl-CoA carboxylase (ACC) and the rapamycin-sensitive adaptor protein of mTOR (Raptor) and, related to this, impairment of ACC1-mediated lipid synthesis and the mechanistic target of the rapamycin complex-1 (mTORC1) pathway. Since blockade of mTOR by Torin-2 as well as downregulation of ACC1 by siRNA also decreased HSV-1 replication, MK-8722 is likely to exert its anti-viral effect via mTORC1 and ACC1 inhibition. Importantly, MK-8722 was able to reduce virus replication even when added after HSV-1. Together, our data highlight the importance of endothelial cells as host cells for HSV-1 replication upon systemic infection and identify AMPK, a metabolic host cell protein, as a potential target for antiviral strategies against HSV-1 infection and its severe consequences. IMPORTANCE Herpes simplex virus type 1 (HSV-1) is a common pathogen that causes blisters or cold sores in humans. It remains latent in infected individuals and can be reactivated multiple times. In adverse conditions, for instance, in immunocompromised patients, HSV-1 can lead to serious complications such as encephalitis, meningitis, or blindness. In these situations, infection of endothelial cells lining the surface of blood vessels may contribute to the manifestation of disease. Here, we describe the role of AMP-activated protein kinase (AMPK), a potent regulator of cellular energy metabolism, in HSV-1 replication in endothelial cells. While downregulation of AMPK potentiates HSV-1 replication, pharmacological AMPK activation inhibits it by limiting the availability of required host cell macromolecules such as proteins or fatty acids. These data highlight the role of metabolic host cell proteins as antiviral targets and reveal activation of endothelial AMPK as a potential strategy to protect from severe consequences of HSV-1 infection.

Natural Phytochemicals as SIRT Activators-Focus on Potential Biochemical Mechanisms

Sirtuins are a family of proteins with enzymatic activity. There are seven mammalian sirtuins (SIRT1-SIRT7) that are found in different cellular compartments. They are a part of crucial cellular pathways and are regulated by many factors, such as chemicals, environmental stress, and phytochemicals. Several in vitro and in vivo studies have presented their involvement in anti-inflammatory, antioxidant, and antiapoptotic processes. Recent findings imply that phytochemicals such as resveratrol, curcumin, quercetin, fisetin, berberine, and kaempferol may regulate the activity of sirtuins. Resveratrol mainly activates SIRT1 and indirectly activates AMPK. Curcumin influences mainly SIRT1 and SIRT3, but its activity is broad, and many pathways in different cells are affected. Quercetin mainly modulates SIRT1, which triggers antioxidant and antiapoptotic responses. Fisetin, through SIRT1 regulation, modifies lipid metabolism and anti-inflammatory processes. Berberine has a wide spectrum of effects and a significant impact on SIRT1 signaling pathways. Finally, kaempferol triggers anti-inflammatory and antioxidant effects through SIRT1 induction. This review aims to summarize recent findings on the properties of phytochemicals in the modulation of sirtuin activity, with a particular focus on biochemical aspects.

Echinacoside ameliorates 5-fluorouracil-induced endothelial injury and senescence through SIRT1 activation

Echinacoside (ECH) is a natural bioactive component with antioxidant, anti-inflammatory, anti-apoptosis, and anti-tumor properties. In the current study, we explore the ECH-mediated protective effect and underlying mechanism of 5-fluorouracil (5-FU)-induced endothelial injury and senescence in the Human umbilical vein endothelial cells (HUVECs). In HUVECs, Cell viability, Apoptosis and Senescence assays evaluated 5-fluorouracil-induced endothelial injury and senescence. Protein expressions were assessed using RT-qPCR and Western blotting. Our results showed that 5-FU-induced endothelial injury and endothelial cell senescence could be improved when treated with ECH in HUVECs. ECH treatment potentially attenuated oxidative stress and ROS production in HUVECs. In addition, the effect of ECH on autophagy markedly reduced the percentage of HUVECs with LC3-II dots and suppressed the Beclin-1 and ATG7 mRNA expression but enhanced the p62 mRNA expression. Besides, ECH treatment significantly increased migrated cells and suppressed the adhesion of THP-1 monocytes in HUVECs. Furthermore, ECH treatment activated the SIRT1 pathway, and its related proteins (SIRT1, p-AMPK and eNOS) expression increased. Nicotinamide (NAM), an inhibitor of SIRT1, significantly attenuated the ECH-induced decrease in the apoptotic rate, increased SA-β-gal-positive cells and significantly reversed the ECH-induced reduction of endothelial senescence. Our results demonstrated that ECH employed endothelial injury and senescence in HUVECs via activation of the SIRT1 pathway.

Quercetin activates the Sestrin2/AMPK/SIRT1 axis to improve amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease with poor prognosis. The intricacies surrounding its pathophysiology could partly account for the lack of effective treatment for ALS. Sestrin2 has been reported to improve metabolic, cardiovascular and neurodegenerative diseases, and is involved in the direct and indirect activation of the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/silent information regulator 1 (SIRT1) axis. Quercetin, as a phytochemical, has considerable biological activities, such as anti-oxidation, anti-inflammation, anti-tumorigenicity, and neuroprotection. Interestingly, quercetin can activate the AMPK/SIRT1 signaling pathway to reduce endoplasmic reticulum stress, and alleviate apoptosis and inflammation. This report examines the molecular relationship between Sestrin2 and AMPK/SIRT1 axis, as well as the main biological functions and research progress of quercetin, together with the correlation between quercetin and Sestrin2/AMPK/SIRT1 axis in neurodegenerative diseases.

Sirt1 Negatively Regulates Cellular Antiviral Responses by Preventing the Cytoplasmic Translocation of Interferon-Inducible Protein 16 in Human Cells

Interferon-inducible protein 16 (IFI16) plays a critical role in antiviral innate immune responses against DNA viruses. Although the acetylation of IFI16 is crucial to its cytoplasmic translocation and downstream signal transduction, the regulation of IFI16 acetylation remains unclear. In this study, we demonstrated that the NAD-dependent deacetylase silent information regulatory 1 (Sirtuin1, Sirt1) interacted with IFI16 and decreased the acetylation of IFI16, resulting in the inhibition of IFI16 cytoplasmic localization and antiviral responses against DNA virus and viral DNA in human cells. Meantime, Sirt1 could not inhibit RNA virus-triggered signal transduction. Interestingly, even p204, the murine ortholog of human IFI16, barely interacted with Sirt1. Thus, Sirt1 could not negatively regulate the acetylation of p204 and subsequent signal transduction upon herpes simplex virus 1 (HSV-1) infection in mouse cells. Taken together, our research work showed a new mechanism by which Sirt1 manipulated IFI16-mediated host defense. Our study also demonstrated a difference in the regulation of antiviral host defense between humans and mice, which might be considered in preclinical studies for antiviral treatment. IMPORTANCE DNA viruses, such as hepatitis B virus (HBV), human papillomavirus (HPV), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), and herpes simplex virus (HSV), can cause a wide range of diseases and are considered a global threat to human health. Interferon-inducible protein 16 (IFI16) binds virus DNA and triggers antiviral innate immune responses to restrict viral infection. In this study, we identified that silent information regulatory 1 (Sirtuin1, Sirt1) interacted with IFI16 and regulated IFI16-mediated innate host defense. Therefore, the activator or inhibitor of Sirt1 may have the potential to be used as a novel strategy to treat DNA virus-associated diseases. We also found that Sirt1 barely interacted with p204, the murine ortholog of human IFI16, and could not negatively regulate innate immune responses upon HSV-1 infection in mouse cells. This difference between humans and mice in the regulation of antiviral host defense might be considered in preclinical studies for antiviral treatment.

An Insight into Current Treatment Strategies, Their Limitations, and Ongoing Developments in Vaccine Technologies against Herpes Simplex Infections

Herpes simplex virus (HSV) infection, the most prevalent viral infection that typically lasts for a lifetime, is associated with frequent outbreaks of oral and genital lesions. Oral herpes infection is mainly associated with HSV-1 through oral contact, while genital herpes originates due to HSV-2 and is categorized under sexually transmitted diseases. Immunocompromised patients and children are more prone to HSV infection. Over the years, various attempts have been made to find potential targets for the prevention of HSV infection. Despite the global distress caused by HSV infections, there are no licensed prophylactic and therapeutic vaccines available on the market against HSV. Nevertheless, there are numerous promising candidates in the pre-clinical and clinical stages of study. The present review gives an overview of two herpes viruses, their history, and life cycle, and different treatments adopted presently against HSV infections and their associated limitations. Majorly, the review covers the recent investigations being carried out globally regarding various vaccine strategies against oral and genital herpes virus infections, together with the recent and advanced nanotechnological approaches for vaccine development. Consequently, it gives an insight to researchers as well as people from the health sector about the challenges and upcoming solutions associated with treatment and vaccine development against HSV infections.

Nicotinamide n-Oxide Attenuates HSV-1-Induced Microglial Inflammation through Sirtuin-1/NF-κB Signaling

HSV-1 is a typical neurotropic virus that infects the brain and causes keratitis, cold sores, and occasionally, acute herpes simplex encephalitis (HSE). The large amount of proinflammatory cytokines induced by HSV-1 infection is an important cause of neurotoxicity in the central nervous system (CNS). Microglia, as resident macrophages in CNS, are the first line of defense against neurotropic virus infection. Inhibiting the excessive production of inflammatory cytokines in overactivated microglia is a crucial strategy for the treatment of HSE. In the present study, we investigated the effect of nicotinamide n-oxide (NAMO), a metabolite mainly produced by gut microbe, on HSV-1-induced microglial inflammation and HSE. We found that NAMO significantly inhibits the production of cytokines induced by HSV-1 infection of microglia, such as IL-1β, IL-6, and TNF-α. In addition, NAMO promotes the transition of microglia from the pro-inflammatory M1 type to the anti-inflammatory M2 type. More detailed studies revealed that NAMO enhances the expression of Sirtuin-1 and its deacetylase enzymatic activity, which in turn deacetylates the p65 subunit to inhibit NF-κB signaling, resulting in reduced inflammatory response and ameliorated HSE pathology. Therefore, Sirtuin-1/NF-κB axis may be promising therapeutic targets against HSV-1 infection-related diseases including HSE.

Transcription Factors as Targets of Natural Compounds in Age-Related Diseases and Cancer: Potential Therapeutic Applications

Inflammation exacerbates systemic pathophysiological conditions and chronic inflammation is a sustained and systemic phenomenon that aggravates aging that can lead to chronic age-related diseases. These inflammatory phenomena have recently been redefined and delineated at the molecular, cellular, and systemic levels. Many transcription factors that are activated in response to tumor metabolic state have been reported to be regulated by a class of histone deacetylase called sirtuins (SIRTs). Sirtuins play a pivotal role in the regulation of tumor cell metabolism, proliferation, and angiogenesis, including oxidative stress and inflammation. The SIRT1-mediated signaling pathway in diabetes and cancer is the SIRT1/forkhead-box class O (FoxO)/nuclear factor-kappa B (NF-κB) pathway. In this review, we describe the accumulation of SIRT1-, NF-κB-, and FoxO-mediated inflammatory processes and cellular proinflammatory signaling pathways. We also describe the proinflammatory mechanisms underlying metabolic molecular pathways in various diseases such as liver cancer and diabetes. Finally, the regulation of cancer and diabetes through the anti-inflammatory effects of natural compounds is highlighted. Evidence from inflammation studies strongly suggests that cells may be a major source of cytokines secreted during various diseases. A better understanding of the mechanisms that underpin the inflammatory response and palliative role of natural compounds will provide insights into the molecular mechanisms of inflammation and various diseases for potential intervention.

Oxidative stress and inflammation regulation of sirtuins: New insights into common oral diseases

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)⁺-dependent histone deacetylases, comprising seven members SIRT1-SIRT7. Sirtuins have been extensively studied in regulating ageing and age-related diseases. Sirtuins are also pivotal modulators in oxidative stress and inflammation, as they can regulate the expression and activation of downstream transcriptional factors (such as Forkhead box protein O3 (FOXO3a), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB)) as well as antioxidant enzymes, through epigenetic modification and post-translational modification. Most importantly, studies have shown that aberrant sirtuins are involved in the pathogenesis of infectious and inflammatory oral diseases, and oral cancer. In this review, we provide a comprehensive overview of the regulatory patterns of sirtuins at multiple levels, and the essential roles of sirtuins in regulating inflammation, oxidative stress, and bone metabolism. We summarize the involvement of sirtuins in several oral diseases such as periodontitis, apical periodontitis, pulpitis, oral candidiasis, oral herpesvirus infections, dental fluorosis, and oral cancer. At last, we discuss the potential utilization of sirtuins as therapeutic targets in oral diseases.

Therapeutic application of quercetin in aging-related diseases: SIRT1 as a potential mechanism

Quercetin, a naturally non-toxic flavonoid within the safe dose range with antioxidant, anti-apoptotic and anti-inflammatory properties, plays an important role in the treatment of aging-related diseases. Sirtuin 1 (SIRT1), a member of NAD+-dependent deacetylase enzyme family, is extensively explored as a potential therapeutic target for attenuating aging-induced disorders. SIRT1 possess beneficial effects against aging-related diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), Depression, Osteoporosis, Myocardial ischemia (M/I) and reperfusion (MI/R), Atherosclerosis (AS), and Diabetes. Previous studies have reported that aging increases tissue susceptibility, whereas, SIRT1 regulates cellular senescence and multiple aging-related cellular processes, including SIRT1/Keap1/Nrf2/HO-1 and SIRTI/PI3K/Akt/GSK-3β mediated oxidative stress, SIRT1/NF-κB and SIRT1/NLRP3 regulated inflammatory response, SIRT1/PGC1α/eIF2α/ATF4/CHOP and SIRT1/PKD1/CREB controlled phosphorylation, SIRT1-PINK1-Parkin mediated mitochondrial damage, SIRT1/FoxO mediated autophagy, and SIRT1/FoxG1/CREB/BDNF/Trkβ-catenin mediated neuroprotective effects. In this review, we summarized the role of SIRT1 in the improvement of the attenuation effect of quercetin on aging-related diseases and the relationship between relevant signaling pathways regulated by SIRT1. Moreover, the functional regulation of quercetin in aging-related markers such as oxidative stress, inflammatory response, mitochondrial function, autophagy and apoptosis through SIRT1 was discussed. Finally, the prospects of an extracellular vesicles (EVs) as quercetin loading and delivery, and SIRT1-mediated EVs as signal carriers for treating aging-related diseases, as well as discussed the ferroptosis alleviation effects of quercetin to protect against aging-related disease via activating SIRT1. Generally, SIRT1 may serve as a promising therapeutic target in the treatment of aging-related diseases via inhibiting oxidative stress, reducing inflammatory responses, and restoring mitochondrial dysfunction.

MicroRNA miR-155 inhibits cyprinid herpesvirus 3 replication via regulating AMPK-MAVS-IFN axis

Since emerged in the late 1990s, cyprinid herpesvirus 3 (CyHV-3) has caused huge economic losses in common and koi carp culture worldwide. Accumulating evidences suggest that teleost fish microRNA (miRNA), a class of non-coding RNA of ∼22 nucleotides, can participate in many cellular processes, especially in host antiviral defenses. However, the roles of miRNAs in CyHV-3 infection are still unclear. Here, using high-throughput miRNA sequencing and quantitative real-time PCR (qRT-PCR) verification, we found that miR-155 was significantly upregulated in common carp brain (CCB) cells upon CyHV-3 infection. Overexpression of miR-155 effectively inhibited CyHV-3 replication in CCB cells and promoted type I interferon (IFN-I) expression. Further study revealed that miR-155 targeted the 3' untranslated region (UTR) of the mRNA of 5'AMP-activated protein kinase (AMPK), and that AMPK could interact with and degrade the mitochondrial antiviral signaling protein (MAVS), resulting in the reduction of interferon (IFN) expression. Collectively, our results show that miR-155, induced by CyHV-3 infection, exhibits anti-CyHV-3 activity via regulating AMPK-MAVS-IFN axis, which will help design anti-CyHV-3 drugs.

Deciphering therapeutic options for neurodegenerative diseases: insights from SIRT1

Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD +)-dependent protein deacetylase that exerts biological effects through nucleoplasmic transfer. Recent studies have highlighted that SIRT1 deacetylates protein substrates to exert its neuroprotective effects, including decreased oxidative stress and inflammatory, increases autophagy, increases levels of nerve growth factors (correlated with behavioral changes), and maintains neural integrity (affects neuronal development and function) in aging or neurological disorder. In this review, we highlight the molecular mechanisms underlying the protective role of SIRT1 in modulating neurodegeneration, focusing on protein homeostasis, aging-related signaling pathways, neurogenesis, and synaptic plasticity. Meanwhile, the potential of targeting SIRT1 to block the occurrence and progression of neurodegenerative diseases is also discussed. Taken together, this review provides an up-to-date evaluation of our current understanding of the neuroprotective mechanisms of SIRT1 and also be involved in the potential therapeutic opportunities of AD and related neurodegenerative diseases.

Promising Natural Products in New Drug Design, Development, and Therapy for Skin Disorders: An Overview of Scientific Evidence and Understanding Their Mechanism of Action

The skin is the largest organ in the human body, composed of the epidermis and the dermis. It provides protection and acts as a barrier against external menaces like allergens, chemicals, systemic toxicity, and infectious organisms. Skin disorders like cancer, dermatitis, psoriasis, wounds, skin aging, acne, and skin infection occur frequently and can impact human life. According to a growing body of evidence, several studies have reported that natural products have the potential for treating skin disorders. Building on this information, this review provides brief information about the action of the most important in vitro and in vivo research on the use of ten selected natural products in inflammatory, neoplastic, and infectious skin disorders and their mechanisms that have been reported to date. The related studies and articles were searched from several databases, including PubMed, Google, Google Scholar, and ScienceDirect. Ten natural products that have been reported widely on skin disorders were reviewed in this study, with most showing anti-inflammatory, antioxidant, anti-microbial, and anti-cancer effects as the main therapeutic actions. Overall, most of the natural products reported in this review can reduce and suppress inflammatory markers, like tumor necrosis factor-alpha (TNF-α), scavenge reactive oxygen species (ROS), induce cancer cell death through apoptosis, and prevent bacteria, fungal, and virus infections indicating their potentials. This review also highlighted the challenges and opportunities of natural products in transdermal/topical delivery systems and their safety considerations for skin disorders. Our findings indicated that natural products might be a low-cost, well-tolerated, and safe treatment for skin diseases. However, a larger number of clinical trials are required to validate these findings. Natural products in combination with modern drugs, as well as the development of novel delivery mechanisms, represent a very promising area for future drug discovery of these natural leads against skin disorders.

Human Sirtuin Regulators: The "Success" Stories

The human sirtuins are a group of NAD⁺-dependent protein deacylases. They “erase” acyl modifications from lysine residues in various cellular targets including histones, transcription factors, and metabolic enzymes. Through these far-reaching activities, sirtuins regulate a diverse array of biological processes ranging from gene transcription to energy metabolism. Human sirtuins have been intensely pursued by both academia and industry as therapeutic targets for a broad spectrum of diseases such as cancer, neurodegenerative diseases, and metabolic disorders. The last two decades have witnessed a flood of small molecule sirtuin regulators. However, there remain relatively few compounds targeting human sirtuins in clinical development. This reflects the inherent issues concerning the development of isoform-selective and potent molecules with good drug-like properties. In this article, small molecule sirtuin regulators that have advanced into clinical trials will be discussed in details as “successful” examples for future drug development. Special attention is given to the discovery of these compounds, the mechanism of action, pharmacokinetics analysis, formulation, as well as the clinical outcomes observed in the trials.

Quercus acuta Thunb. (Fagaceae) and Its Component, Isoquercitrin, Inhibit HSV-1 Replication by Suppressing Virus-Induced ROS Production and NF-κB Activation

HSV-1 is a neurotropic virus that replicates lytically during acute infection and establishes latency in peripheral neurons. Currently, the clinically approved compounds for the prevention of HSV-1 infection include acyclovir and penciclovir; however, long-term use of the drug is associated with serious side effects, and drug-resistant strains often appear. Therefore, it is important to find a safe and novel antiviral agent for HSV-1 infection. Quercus acuta Thunb. (Fagaceae) (QA) is widely distributed as an ornamental and dietary plant in Korea, Taiwan, China, and Japan. Thus far, the effects of QA extract and its active ingredients are known to have antioxidant, antibacterial, and anti-inflammatory activity, but studies of possible antiviral effects have not been reported. We studied the antiviral effects and molecular mechanism of QA after HSV-1 infection at the cellular level. We confirmed that QA suppresses ROS expression after HSV-1 infection and also suppresses inflammatory cytokine expression through inhibition of NF-кB activity. In addition, we found that QA increases the phosphorylation activity of IRF3 through induction of TBK1 activity during HSV-1 infection. QA exhibits an antiviral effect, and we confirmed through UPLC-DAD-mass spectrometer (MS)/MS analysis that it contains five main components: catechin, chlorogenic acid, fraxin, isoquercitrin, and taxifolin. Of these, isoquercitrin was confirmed to exhibit an antiviral effect on SK-N-SH cells through ICP27 inhibition. Overall, our results suggest that QA is a novel inhibitor with antiviral effects against HSV-1 infection and may be used specifically to prevent and treat of herpes simplex virus encephalitis infection.

Polyphenols and neuroprotection: Therapeutic implications for cognitive decline

Dietary polyphenols have been the focus of major interest for their potential benefits on human health. Several preclinical studies have been conducted to provide a rationale for their potential use as therapeutic agents in preventing or ameliorating cognitive decline. However, results from human studies are scarce and poorly documented. The aim of this review was to discuss the potential mechanisms involved in age-related cognitive decline or early stage cognitive impairment and current evidence from clinical human studies conducted on polyphenols and the aforementioned outcomes. The evidence published so far is encouraging but contrasting findings are to be taken into account. Most studies on anthocyanins showed a consistent positive effect on various cognitive aspects related to aging or early stages of cognitive impairment. Studies on cocoa flavanols, resveratrol, and isoflavones provided substantial contrasting results and further research is needed to clarify the therapeutic potential of these compounds. Results from other studies on quercetin, green tea flavanols, hydroxycinnamic acids (such as chlorogenic acid), curcumin, and olive oil tyrosol and derivatives are rather promising but still too few to provide any real conclusions. Future translational studies are needed to address issues related to dosage, optimal formulations to improve bioavailability, as well as better control for the overall diet, and correct target population.

RACK1 T50 Phosphorylation by AMPK Potentiates Its Binding with IRF3/7 and Inhibition of Type 1 IFN Production

The receptor for activated C kinase 1 (RACK1) adaptor protein has been implicated in viral infection. However, whether RACK1 promotes in vivo viral infection in mammals remains unknown. Moreover, it remains elusive how RACK1 is engaged in antiviral innate immune signaling. In this study, we report that myeloid RACK1 deficiency does not affect the development and survival of myeloid cells under resting conditions but renders mice less susceptible to viral infection. RACK1-deficient macrophages produce more IFN-α and IFN-β in response to both RNA and DNA virus infection. In line with this, RACK1 suppresses transcriptional activation of type 1 IFN gene promoters in response to virus infection. Analysis of virus-mediated signaling indicates that RACK1 inhibits the phosphorylation of IRF3/7. Indeed, RACK1 interacts with IRF3/7, which is enhanced after virus infection. Further exploration indicates that virus infection triggers AMPK activation, which in turn phosphorylates RACK1 at Thr⁵⁰ RACK1 phosphorylation at Thr⁵⁰ enhances its interaction with IRF3/7 and thereby limits IRF3/7 phosphorylation. Thus, our results confirm that myeloid RACK1 promotes in vivo viral infection and provide insight into the control of type 1 IFN production in response to virus infection.

Mechanistic insights and perspectives involved in neuroprotective action of quercetin

Neurodegenerative diseases (NDDs) are the primary cause of disabilities in the elderly people. Growing evidence indicates that oxidative stress, mitochondrial dysfunction, neuroinflammation and apoptosis are associated with aging and the basis of most neurodegenerative disorders. Quercetin is a flavonoid with significant pharmacological effects and promising therapeutic potential. It is widely distributed among plants and typically found in daily diets mainly in fruits and vegetables. It shows a number of biological properties connected to its antioxidant activity. Neuroprotection by quercetin has been reported in many in vitro as well as in in vivo studies. However, the exact mechanism of action is still mystery and similarly there are a number of hypothesis exploring the mechanism of neuroprotection. Quercetin enhances neuronal longevity and neurogenesis by modulating and inhibiting wide number of pathways. This review assesses the food sources of quercetin, its pharmacokinetic profile, structure activity relationship and its pathophysiological role in various NDDs and it also provides a synopsis of the literature exploring the relationship between quercetin and various downstream signalling pathways modulated by quercetin for neuroprotection for eg. nuclear factor erythroid 2-related factor 2 (Nrf2), Paraoxonase-2 (PON2), c-Jun N-terminal kinase (JNK), Tumour Necrosis Factor alpha (TNF-α), Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α), Sirtuins, Mitogen-activated protein kinases (MAPKs) signalling cascades, CREB (Cyclic AMP response element binding protein) and Phosphoinositide 3- kinase(PI3K/Akt). Therefore, the aim of the present review was to elaborate on the cellular and molecular mechanisms of the quercetin involved in the protection against NDDs.

Multifaceted Role of AMPK in Viral Infections

Viral pathogens often exploit host cell regulatory and signaling pathways to ensure an optimal environment for growth and survival. Several studies have suggested that 5'-adenosine monophosphate-activated protein kinase (AMPK), an intracellular serine/threonine kinase, plays a significant role in the modulation of infection. Traditionally, AMPK is a key energy regulator of cell growth and proliferation, host autophagy, stress responses, metabolic reprogramming, mitochondrial homeostasis, fatty acid β-oxidation and host immune function. In this review, we highlight the modulation of host AMPK by various viruses under physiological conditions. These intracellular pathogens trigger metabolic changes altering AMPK signaling activity that then facilitates or inhibits viral replication. Considering the COVID-19 pandemic, understanding the regulation of AMPK signaling following infection can shed light on the development of more effective therapeutic strategies against viral infectious diseases.

Herpes Simplex Virus Type 1 Neuronal Infection Triggers the Disassembly of Key Structural Components of Dendritic Spines

Herpes simplex virus type 1 (HSV-1) is a widespread neurotropic virus. Primary infection of HSV-1 in facial epithelium leads to retrograde axonal transport to the central nervous system (CNS) where it establishes latency. Under stressful conditions, the virus reactivates, and new progeny are transported anterogradely to the primary site of infection. During the late stages of neuronal infection, axonal damage can occur, however, the impact of HSV-1 infection on the morphology and functional integrity of neuronal dendrites during the early stages of infection is unknown. We previously demonstrated that acute HSV-1 infection in neuronal cell lines selectively enhances Arc protein expression - a major regulator of long-term synaptic plasticity and memory consolidation, known for being a protein-interaction hub in the postsynaptic dendritic compartment. Thus, HSV-1 induced Arc expression may alter the functionality of infected neurons and negatively impact dendritic spine dynamics. In this study we demonstrated that HSV-1 infection induces structural disassembly and functional deregulation in cultured cortical neurons, an altered glutamate response, Arc accumulation within the somata, and decreased expression of spine scaffolding-like proteins such as PSD-95, Drebrin and CaMKIIβ. However, whether these alterations are specific to the HSV-1 infection mechanism or reflect a secondary neurodegenerative process remains to be determined.

Medicinal plants: Treasure for antiviral drug discovery

The pandemic of viral diseases like novel coronavirus (2019-nCoV) prompted the scientific world to examine antiviral bioactive compounds rather than nucleic acid analogous, protease inhibitors, or other toxic synthetic molecules. The emerging viral infections significantly associated with 2019-nCoV have challenged humanity's survival. Further, there is a constant emergence of new resistant viral strains that demand novel antiviral agents with fewer side effects and cell toxicity. Despite significant progress made in immunization and regenerative medicine, numerous viruses still lack prophylactic vaccines and specific antiviral treatments that are so often influenced by the generation of viral escape mutants. Of importance, medicinal herbs offer a wide variety of therapeutic antiviral chemotypes that can inhibit viral replication by preventing viral adsorption, adhering to cell receptors, inhibiting virus penetration in the host cell, and competing for pathways of activation of intracellular signals. The present review will comprehensively summarize the promising antiviral activities of medicinal plants and their bioactive molecules. Furthermore, it will elucidate their mechanism of action and possible implications in the treatment/prevention of viral diseases even when their mechanism of action is not fully understood, which could serve as the base for the future development of novel or complementary antiviral treatments.

Aspirin and 5-Aminoimidazole-4-carboxamide Riboside Attenuate Bovine Ephemeral Fever Virus Replication by Inhibiting BEFV-Induced Autophagy

Recent study in our laboratory has demonstrated that BEFV-induced autophagy via activation of the PI3K/Akt/NF-κB and Src/JNK pathways and suppression of the PI3K-AKt-mTORC1 pathway is beneficial for virus replication. In the current study, we found that both aspirin and 5-aminoimidazole-4-carboxamide-1-β-riboside (AICAR) siginificantly attenuated virus replication by inhibiting BEFV-induced autophagy via suppressing the BEFV-activated PI3K/Akt/NF-κB and Src/JNK pathways as well as inducing reversion of the BEFV-suppressed PI3K-Akt-mTORC1 pathway. AICAR reversed the BEFV-activated PI3K/Akt/NF-κB and Src/JNK pathways at the early to late stages of infection and induced reversion of the BEFV-suppressed PI3K-AKt-mTORC1 pathway at the late stage of infection. Our findings reveal that inhibition of BEFV-induced autophagy by AICAR is independent of AMPK. Furthermore, we found that AICAR transcriptionally downregulates the ATG related genes ULK1, Beclin 1, and LC3 and enhances Atg7 degradation by the proteasome pathway. Aspirin suppresses virus replication by inhibiting BEFV-induced autophagy. It directly suppressed the NF-κB pathway and reversed the BEFV-activated Src/JNK pathway at the early stage of infection and reversed the BEFV-suppressed PI3K/Akt/mTOR pathway at the late stage of infection. The current study provides mechanistic insights into the effects of aspirin and AICAR on BEFV replication through suppression of BEFV-induced autophagy.

Cell Clearing Systems as Targets of Polyphenols in Viral Infections: Potential Implications for COVID-19 Pathogenesis

The novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated the ongoing coronavirus disease-2019 (COVID-19) pandemic, still with an uncertain outcome. Besides pneumonia and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), other features became evident in the context of COVID-19. These includes endothelial and coagulation dysfunction with disseminated intravascular coagulation (DIC), and multiple organ dysfunction syndrome (MODS), along with the occurrence of neurological alterations. The multi-system nature of such viral infection is a witness to the exploitation and impairment of ubiquitous subcellular and metabolic pathways for the sake of its life-cycle, ranging from host cell invasion, replication, transmission, up to a cytopathic effect and overt systemic inflammation. In this frame, alterations in cell-clearing systems of the host are emerging as a hallmark in the pathogenesis of various respiratory viruses, including SARS-CoV-2. Indeed, exploitation of the autophagy and proteasome pathways might contribute not only to the replication of the virus at the site of infection but also to the spreading of either mature virions or inflammatory mediators at both cellular and multisystem levels. In this frame, besides a pharmacological therapy, many researchers are wondering if some non-pharmacological substances might counteract or positively modulate the course of the infection. The pharmacological properties of natural compounds have gained increasing attention in the field of alternative and adjunct therapeutic approaches to several diseases. In particular, several naturally-occurring herbal compounds (mostly polyphenols) are reported to produce widespread antiviral, anti-inflammatory, and anti-oxidant effects while acting as autophagy and (immuno)-proteasome modulators. This article attempts to bridge the perturbation of autophagy and proteasome pathways with the potentially beneficial effects of specific phytochemicals and flavonoids in viral infections, with a focus on the multisystem SARS-CoV-2 infection.

Supplementation with Red Wine Extract Increases Insulin Sensitivity and Peripheral Blood Mononuclear Sirt1 Expression in Nondiabetic Humans

The aim of this study was to investigate the effects of dietary supplementation with a nonalcoholic red wine extract (RWE), including resveratrol and polyphenols, on insulin sensitivity and Sirt1 expression in nondiabetic humans. The present study was a single-arm, open-label and prospective study. Twelve subjects received supplementation with RWE, including 19.2 mg resveratrol and 136 mg polyphenols, daily for 8 weeks. After 8 weeks, metabolic parameters, including glucose/lipid metabolism and inflammatory markers, were evaluated. mRNA expression of Sirt1 was evaluated in isolated peripheral blood mononuclear cells (PBMNCs). Additionally, Sirt1 and phosphorylated AMP-activated kinase (p-AMPK) expression were evaluated in cultured human monocytes (THP-1 cells). Supplementation with RWE for 8 weeks decreased the homeostasis model assessment for insulin resistance (HOMA-IR), which indicates an increase in insulin sensitivity. Serum low-density lipoprotein-cholesterol (LDL-C), triglyceride (TG) and interleukin-6 (IL-6) were significantly decreased by RWE supplementation for 8 weeks. Additionally, Sirt1 mRNA expression in isolated PBMNCs was significantly increased after 8 weeks of RWE supplementation. Moreover, the rate of increase in Sirt1 expression was positively correlated with the rate of change in HOMA-IR. The administration of RWE increased Sirt1 and p-AMPK expression in cultured THP-1 cells. Supplementation with RWE improved metabolism, such as insulin sensitivity, lipid profile and inflammation, in humans. Additionally, RWE supplementation induced an increase in Sirt1 expression in PBMNCs, which may be associated with an improvement in insulin sensitivity.

Overview of biological effects of Quercetin on ovary

Over the last few decades, using natural products has been increased to treat different diseases. Today, great attention has been pointed toward the usage of natural products such as flavonoids, especially Quercetin (QUR), in the treatment of diseases. QUR as a natural antioxidant has been traditionally used to prevent or treat a variety of diseases such as cancer, cardiovascular disease, polycystic ovary syndrome (PCOS), obesity, chronic inflammation, and reproductive system dysfunction. Several studies demonstrated that QUR acts as an anti-inflammatory, anti-apoptotic, antioxidant, and anticancer agent. With this in view, in this study, we intended to describe an overview of the biological effects of QUR on the ovary. QUR improves the quality of oocytes and embryos. It affects the proliferation and apoptosis and decreases the oxidative stress in granulosa cells (GCs). Furthermore, QUR can be used as a complementary and alternative therapy in ovarian cancer and it has beneficial effects in the treatment of PCOS patients. It seems that QUR as a supplementary factor has different activities for the treatment of different disorders and it also has bidirectional activities. However, further investigations are needed for understanding the efficacy of QUR in the treatment and improvement of gynecological patients.

Effect of Quercetin on PC12 Alzheimer's Disease Cell Model Induced by Aβ 25-35 and Its Mechanism Based on Sirtuin1/Nrf2/HO-1 Pathway

Objective

This study is aimed at studying the effect of quercetin on the Alzheimer disease cell model induced by Aβ_25-35 in PC12 cells and its mechanism of action.

Methods

The AD cell model was established by Aβ_25-35. Quercetin was used at different concentrations (0, 10, 20, 40, and 80 μmol/L). The morphology of cells was observed, and the effect on cell survival rate was detected by the MTT method. Cell proliferation was detected by the SRB method. The contents of LDH, SOD, MDA, GSH-Px, AChE, CAT, and T-AOC were detected by kits. The expression of sirtuin1/Nrf2/HO-1 was detected by RT-qPCR and Western blot.

Results

PC12 cells in the control group grew quickly and adhered well to the wall, most of which had extended long axons and easily grew into clusters. In the model group, cells were significantly damaged and the number of cells was significantly reduced. It was found that PC12 cells were swollen, rounded, protruding, and retracting, with reduced adherent function and floating phenomenon. Quercetin could increase the survival rate and proliferation rate of PC12 cells; reduce the levels of LDH, AChE, MDA, and HO-1 protein; and increase the levels of SOD, GSH-Px, CAT, T-AOC, sirtuin1, and Nrf2 protein.

Conclusion

Quercetin can increase the survival rate of PC12 injured by Aβ_25-35, promote cell proliferation, and antagonize the toxicity of Aβ; it also has certain neuroprotective effects. Therefore, quercetin is expected to become a drug for the treatment of AD.

Disturbed Yin-Yang balance: stress increases the susceptibility to primary and recurrent infections of herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1), a neurotropic herpes virus, is able to establish a lifelong latent infection in the human host. Following primary replication in mucosal epithelial cells, the virus can enter sensory neurons innervating peripheral tissues via nerve termini. The viral genome is then transported to the nucleus where it can be maintained without producing infectious progeny, and thus latency is established in the cell. Yin–Yang balance is an essential concept in traditional Chinese medicine (TCM) theory. Yin represents stable and inhibitory factors, and Yang represents the active and aggressive factors. When the organism is exposed to stress, especially psychological stress caused by emotional stimulation, the Yin–Yang balance is disturbed and the virus can re-engage in productive replication, resulting in recurrent diseases. Therefore, a better understanding of the stress-induced susceptibility to HSV-1 primary infection and reactivation is needed and will provide helpful insights into the effective control and treatment of HSV-1. Here we reviewed the recent advances in the studies of HSV-1 susceptibility, latency and reactivation. We included mechanisms involved in primary infection and the regulation of latency and described how stress-induced changes increase the susceptibility to primary and recurrent infections.

Current Antivirals and Novel Botanical Molecules Interfering With Herpes Simplex Virus Infection

Herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent within the human population and are characterized by lifelong infections and sporadic recurrences due to latent neuron infection. Upon reactivations, HSVs may manifest either, symptomatically or asymptomatically and be shed onto others through mucosae body fluids. Although, HSVs can produce severe disease in humans, such as life-threatening encephalitis and blindness, the most common symptoms are skin and mucosal lesions in the oro-facial and the genital areas. Nucleoside analogs with antiviral activity can prevent severe HSV infection, yet they are not very effective for treating skin manifestations produced by these viruses, as they only reduce in a few days at most the duration of lesions. Additionally, HSV variants that are resistant to these antivirals may arise, especially in immunosuppressed individuals. Thus, new antivirals that can reduce the severity and duration of these cutaneous manifestations would certainly be welcome. Here, we review currently available anti-herpetic therapies, novel molecules being assessed in clinical trials and new botanical compounds reported in the last 20 years with antiviral activities against HSVs that might represent future treatments against these viruses.

Quercetin protects against diabetic encephalopathy via SIRT1/NLRP3 pathway in db/db mice

Epidemiological studies have found that diabetes and cognitive dysfunction are closely related. Quercetin has been certified with the effect on improving diabetes mellitus (DM) and cognitive impairment. However, the effect and related mechanism of quercetin on diabetic encephalopathy (DE) are still ambiguous. In this study, we used the db/db mice (diabetic model) to discover whether quercetin could improve DE through the Sirtuin1/NLRP3 (NOD‐, LRR‐ and pyrin domain‐containing 3) pathway. Behavioural results (Morris water maze and new object recognition tests) showed that quercetin (70 mg/kg) improved the learning and memory. Furthermore, quercetin alleviated insulin resistance and the level of fasting blood glucose. Besides, Western blot analysis also showed that quercetin increased the protein expressions of nerve‐ and synapse‐related protein, including postsynapticdensity 93 (PSD93), postsynapticdensity 95 (PSD95), brain‐derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the brain of db/db mice. Quercetin also increased the protein expression of SIRT1 and decreased the expression of NLRP3 inflammation‐related proteins, including NLRP3, the adaptor protein ASC and cleaved Caspase‐1, the pro‐inflammatory cytokines IL‐1β and IL‐18. In conclusion, the present results indicate that the SIRT1/NLRP3 pathway may be a crucial mechanism for the neuroprotective effect of quercetin against DE.

Herpes Simplex Virus Type 1 Infection of the Central Nervous System: Insights Into Proposed Interrelationships With Neurodegenerative Disorders

Herpes simplex virus type 1 (HSV-1) is highly prevalent in humans and can reach the brain without evident clinical symptoms. Once in the central nervous system (CNS), the virus can either reside in a quiescent latent state in this tissue, or eventually actively lead to severe acute necrotizing encephalitis, which is characterized by exacerbated neuroinflammation and prolonged neuroimmune activation producing a life-threatening disease. Although HSV-1 encephalitis can be treated with antivirals that limit virus replication, neurological sequelae are common and the virus will nevertheless remain for life in the neural tissue. Importantly, there is accumulating evidence that suggests that HSV-1 infection of the brain both, in symptomatic and asymptomatic individuals could lead to neuronal damage and eventually, neurodegenerative disorders. Here, we review and discuss acute and chronic infection of particular brain regions by HSV-1 and how this may affect neuron and cognitive functions in the host. We review potential cellular and molecular mechanisms leading to neurodegeneration, such as protein aggregation, dysregulation of autophagy, oxidative cell damage and apoptosis, among others. Furthermore, we discuss the impact of HSV-1 infection on brain inflammation and its potential relationship with neurodegenerative diseases.

Herpes Simplex Virus Type 1 Enhances Expression of the Synaptic Protein Arc for Its Own Benefit

Herpes simplex virus type 1 (HSV-1) is a neurotropic virus able to reach the central nervous system (CNS) after primary infection in oronasal mucosa. HSV-1 establishes latency inside neurons due the repression of its gene expression process, which is related to periodic reactivations in response to cellular stress conditions, constituting a risk factor for neurodegenerative diseases such as Alzheimer’s disease (AD). The immediate-early gene Arc plays an essential role in neuronal morphology, synaptic plasticity and memory formation. Arc acts as a hub protein, interacting with components of the endocytic machinery required for AMPA receptor (AMPAR) recycling as well as with proteins of the post-synaptic density and actin cytoskeleton. However, to date, no studies have evaluated whether persistent neurotropic HSV-1 infection modulates the expression or function of Arc protein in brain tissue. Here, we report that neuronal in vivo and in vitro infection of HSV-1 significantly increases Arc protein levels, showing a robust perinuclear distribution in neuronal cell lines, a process that is dependent on an active HSV-1 replication cycle. Finally, we found that silencing Arc protein caused a decrease in HSV-1 proteins and viral progeny, suggesting that Arc is involved in the lifecycle of HSV-1. Our studies strongly suggest that pathogenicity of HSV-1 neuronal reactivations in humans could be mediated in part by Arc neuronal upregulation and its potential role in endocytic trafficking and AMPA-neuronal function impairment. Further studies are necessary to define whether this phenomenon could have repercussions in cognition and learning processes in infected individuals.

AMP-Activated Protein Kinase and Host Defense against Infection

5′-AMP-activated protein kinase (AMPK) plays diverse roles in various physiological and pathological conditions. AMPK is involved in energy metabolism, which is perturbed by infectious stimuli. Indeed, various pathogens modulate AMPK activity, which affects host defenses against infection. In some viral infections, including hepatitis B and C viral infections, AMPK activation is beneficial, but in others such as dengue virus, Ebola virus, and human cytomegaloviral infections, AMPK plays a detrimental role. AMPK-targeting agents or small molecules enhance the antiviral response and contribute to the control of microbial and parasitic infections. In addition, this review focuses on the double-edged role of AMPK in innate and adaptive immune responses to infection. Understanding how AMPK regulates host defenses will enable development of more effective host-directed therapeutic strategies against infectious diseases.

Resveratrol as a Novel Anti-Herpes Simplex Virus Nutraceutical Agent: An Overview

The herpes simplex virus (HSV) is a common human virus affecting many people worldwide. HSV infections manifest with lesions that occur in different parts of the body, including oral, ocular, nasal, and genital skin and mucosa. In rare cases, HSV infections can be serious and lethal. Several anti-HSV drugs have been developed, but the existence of mutant viruses resistant to these drugs led to the individuation of novel antiviral agents. Plant-derived bioactive compounds, and more specifically polyphenols, have been demonstrated to exert marked anti-HSV activity and, among these, resveratrol (RSV) would be considered a good candidate. The purpose of this manuscript is to review the available literature elucidating the efficacy of RSV against HSV and the main demonstrated mechanisms of action.

Interplay Between the Autophagy-Lysosomal Pathway and the Ubiquitin-Proteasome System: A Target for Therapeutic Development in Alzheimer's Disease

Alzheimer’s disease (AD) is the most common cause of age-related dementia leading to severe irreversible cognitive decline and massive neurodegeneration. While therapeutic approaches for managing symptoms are available, AD currently has no cure. AD associates with a progressive decline of the two major catabolic pathways of eukaryotic cells—the autophagy-lysosomal pathway (ALP) and the ubiquitin-proteasome system (UPS)—that contributes to the accumulation of harmful molecules implicated in synaptic plasticity and long-term memory impairment. One protein recently highlighted as the earliest initiator of these disturbances is the amyloid precursor protein (APP) intracellular C-terminal membrane fragment β (CTFβ), a key toxic agent with deleterious effects on neuronal function that has become an important pathogenic factor for AD and a potential biomarker for AD patients. This review focuses on the involvement of regulatory molecules and specific post-translational modifications (PTMs) that operate in the UPS and ALP to control a single proteostasis network to achieve protein balance. We discuss how these aspects can contribute to the development of novel strategies to strengthen the balance of key pathogenic proteins associated with AD.

Dexmedetomidine protects mice against myocardium ischaemic/reperfusion injury by activating an AMPK/PI3K/Akt/eNOS pathway

Acute myocardial ischaemia/reperfusion (MIR) injury leads to severe arrhythmias and has a high rate of lethality. In the present study, we aim to determine the effect of dexmedetomidine (Dex) on heart injury parameters following MIR surgery. We examined the effects of Dex on heart function parameters and infarct size following MIR surgery. Proinflammatory cytokines, oxidative products and anti-oxidative enzymes in the myocardium were measured to evaluate the anti-inflammatory and anti-oxidative effects of Dex. The role of the adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/phosphatidylino-sitol 3-kinase (PI3k)/Akt/endothelial nitric oxide synthase (eNOS) pathway was investigated using their inhibitors. The alteration of haemodynamic parameters, histopathological results, and infarct size caused by MIR was attenuated by Dex. The interleukine-1 beta (IL-1β), IL-6, tumour necrosis factor-a (TNF-α) and myeloperoxidase (MPO) were all significantly decreased. Anti-oxidative enzymes superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were restored by Dex. Oxidative products8-OHdG, MDA and protein carbonyl were all decreased by Dex (P<.05). Dex activated AMPK expression, eNOS and Akt phosphorylation. The influence of Dex on cardiac function was reversed by the inhibitors of the eNOS, AMPK and PI3K/Akt pathways. These results indicate that Dex protected the cardiac functional, histological changes, inflammation and oxidative stress induced by MIR. Our results present a novel signalling mechanism that Dex protects MIR injury by activating an AMPK/PI3K/Akt/eNOS pathway.

AMPK/SIRT1/p38 MAPK signaling pathway regulates alcohol‑induced neurodegeneration by resveratrol

Resveratrol has also been approved for use in enhancing plant disease resistance and reducing pesticide use. A number of studies have shown that the disease resistance of crops treated with resveratrol is markedly improved. The aim of the present study was to examine the protective effect of resveratrol against alcohol‑induced neurodegeneration occurred and its association with AMP‑activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/p38 in rats and humans. ELISA, caspase‑3 activity and western blot analyses were employed in the present study. Sprague‑Dawley rats and human neuroblastoma SH‑SY5Y cells were treated with alcohol to establish the alcohol‑induced model. Resveratrol protected against alcohol‑induced neuron damage in the hippocampus of the rats. Treatment with resveratrol also inhibited the alcohol‑induced inflammatory response, oxidative stress, caspase‑3 activities and B‑cell lymphoma (Bcl‑2)‑associated X protein/Bcl‑2 in the alcohol‑induced rat. Resveratrol also reduced the upregulated protein expression of AMPK and SIRT1, preventing the pro‑apoptotic alcohol‑induced protein expression of p38 in the rats exposed to alcohol. The downregulation of AMPK suppressed the expression of SIRT1 and activated the expression of p38 in the SH‑SY5Y cell model. Taken together, the data obtained suggested that resveratrol protected against alcohol‑induced neurodegeneration via the AMPK/SIRT1/p38 pathway in rats and humans.

Quercetin prevents spinal motor neuron degeneration induced by chronic excitotoxic stimulus by a sirtuin 1-dependent mechanism

Background

Excitotoxicity is a mechanism of foremost importance in the selective motor neuron degeneration characteristic of motor neuron disorders. Effective therapeutic strategies are an unmet need for these disorders. Polyphenols, such as quercetin and resveratrol, are plant-derived compounds that activate sirtuins (SIRTs) and have shown promising results in some models of neuronal death, although their effects have been scarcely tested in models of motor neuron degeneration.

Methods

In this work we investigated the effects of quercetin and resveratrol in an in vivo model of excitotoxic motor neuron death induced by the chronic infusion of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) into the rat spinal cord tissue. Quercetin and resveratrol were co-infused with AMPA and motor behavior and muscle strength were assessed daily for up to ten days. Then, animals were fixed and lumbar spinal cord tissue was analyzed by histological and immunocytological procedures.

Results

We found that the chronic infusion of AMPA [1 mM] caused a progressive motor neuron degeneration, accompanied by astrogliosis and microgliosis, and motor deficits and paralysis of the rear limbs. Quercetin infusion ameliorated AMPA-induced paralysis, rescued motor neurons, and prevented both astrogliosis and microgliosis, and these protective effects were prevented by EX527, a very selective SIRT1 inhibitor. In contrast, neither resveratrol nor EX527 alone improved motor behavior deficits or reduced motor neuron degeneration, albeit both reduced gliosis.

Conclusions

These results suggest that quercetin exerts its beneficial effects through a SIRT1-mediated mechanism, and thus SIRT1 plays an important role in excitotoxic neurodegeneration and therefore its pharmacological modulation might provide opportunities for therapy in motor neuron disorders.

Electronic supplementary material

The online version of this article (10.1186/s40035-017-0102-8) contains supplementary material, which is available to authorized users.

Subversion of Host Responses to Energy Insufficiency by Us3 Supports Herpes Simplex Virus 1 Replication during Stress

Cellular stress responses to energy insufficiency can impact virus reproduction. In particular, activation of the host AMP-activated protein kinase (AMPK) by low energy could limit protein synthesis by inhibiting mTORC1. Although many herpesviruses, including herpes simplex virus 1 (HSV-1), stimulate mTORC1, how HSV-1-infected cells respond to energy availability, a physiological indicator regulating mTORC1, has not been investigated. In addition, the impact of low-energy stress on productive HSV-1 growth and viral genetic determinants potentially enabling replication under physiological stress remains undefined. Here, we demonstrate that mTORC1 activity in HSV-1-infected cells is largely insensitive to stress induced by simulated energy insufficiency. Furthermore, resistance of mTORC1 activity to low-energy-induced stress, while not significantly influenced by the HSV-1 UL46-encoded phosphatidylinositol 3-kinase (PI3K)-Akt activator, was dependent upon the Ser/Thr kinase activity of Us3. A Us3-deficient virus was hypersensitive to low-energy-induced stress as infected cell protein synthesis and productive replication were reduced compared to levels in cells infected with a Us3-expressing virus. Although Us3 did not detectably prevent energy stress-induced AMPK activation, it enforced mTORC1 activation despite the presence of activated AMPK. In the absence of applied low-energy stress, AMPK activity in infected cells was restricted in a Us3-dependent manner. This establishes that the Us3 kinase not only activated mTORC1 but also enabled sustained mTORC1 signaling during simulated energy insufficiency that would otherwise restrict protein synthesis and virus replication. Moreover, it identifies the alphaherpesvirus-specific Us3 kinase as an mTORC1 activator that subverts the host cell energy-sensing program to support viral productive growth irrespective of physiological stress.IMPORTANCE Like all viruses, herpes simplex virus type 1 (HSV-1) reproduction relies upon numerous host energy-intensive processes, the most demanding of which is protein synthesis. In response to low energy, the cellular AMP-activated protein kinase (AMPK) triggers a physiological stress response that antagonizes mTORC1, a multisubunit host kinase that controls protein synthesis. This could restrict virus protein production and growth. Here, we establish that the HSV-1 Us3 protein kinase subverts the normal response to low-energy-induced stress. While Us3 does not prevent AMPK activation by low energy, it enforces mTORC1 activation and overrides a physiological response that couples energy availability and protein synthesis. These results help explain how reproduction of HSV-1, a ubiquitous, medically significant human pathogen causing a spectrum of diseases ranging from the benign to the life threatening, occurs during physiological stress. This is important because HSV-1 reproduction triggered by physiological stress is characteristic of reactivation of lifelong latent infections.

Adenosine Monophosphate (AMP)-Activated Protein Kinase: A New Target for Nutraceutical Compounds

Adenosine monophosphate-activated protein kinase (AMPK) is an important energy sensor which is activated by increases in adenosine monophosphate (AMP)/adenosine triphosphate (ATP) ratio and/or adenosine diphosphate (ADP)/ATP ratio, and increases different metabolic pathways such as fatty acid oxidation, glucose transport and mitochondrial biogenesis. In this sense, AMPK maintains cellular energy homeostasis by induction of catabolism and inhibition of ATP-consuming biosynthetic pathways to preserve ATP levels. Several studies indicate a reduction of AMPK sensitivity to cellular stress during aging and this could impair the downstream signaling and the maintenance of the cellular energy balance and the stress resistance. However, several diseases have been related with an AMPK dysfunction. Alterations in AMPK signaling decrease mitochondrial biogenesis, increase cellular stress and induce inflammation, which are typical events of the aging process and have been associated to several pathological processes. In this sense, in the last few years AMPK has been identified as a very interesting target and different nutraceutical compounds are being studied for an interesting potential effect on AMPK induction. In this review, we will evaluate the interaction of the different nutraceutical compounds to induce the AMPK phosphorylation and the applications in diseases such as cancer, type II diabetes, neurodegenerative diseases or cardiovascular diseases.

The KSHV K1 Protein Modulates AMPK Function to Enhance Cell Survival

Kaposi’s sarcoma herpesvirus (KSHV) is the etiologic agent of Kaposi’s sarcoma (KS) as well as two lymphoproliferative diseases, primary effusion lymphoma and multicentric Castleman’s disease. KSHV encodes viral proteins, such as K1, that alter signaling pathways involved in cell survival. Expression of K1 has been reported to transform rodent fibroblasts, and K1 transgenic mice develop multiple tumors, suggesting that K1 has an important role in KSHV pathogenesis. We found that cells infected with a KSHV virus containing a WT K1 gene had a survival advantage under conditions of nutrient deprivation compared to cells infected with KSHV K1 mutant viruses. 5’ adenosine monophosphate-activated protein kinase (AMPK) responds to nutrient deprivation by maintaining energy homeostasis, and AMPK signaling has been shown to promote cell survival in various types of cancers. Under conditions of AMPK inhibition, we also observed that cells infected with KSHV containing a WT K1 gene had a survival advantage compared to KSHV K1 mutant virus infected cells. To explore the underpinnings of this phenotype, we identified K1-associated cellular proteins by tandem affinity purification and mass spectrometry. We found that the KSHV K1 protein associates with the gamma subunit of AMPK (AMPKγ1). We corroborated this finding by independently confirming that K1 co-immunoprecipitates with AMPKγ1. Co-immunoprecipitations of wild-type K1 (K1_WT) or K1 domain mutants and AMPKγ1, revealed that the K1 N-terminus is important for the association between K1 and AMPKγ1. We propose that the KSHV K1 protein promotes cell survival via its association with AMPKγ1 following exposure to stress.

Infectious agents such as Kaposi’s sarcoma associated herpesvirus (KSHV) are etiologic agents of human cancer. KSHV-infected cells must survive various environmental stresses. Cells infected with KSHV express viral proteins that alter normal cellular processes to promote cell survival and viral persistence. We found that the KSHV K1 protein promotes survival under conditions of cellular stress, and that this survival advantage is at least partially dependent on the association of K1 and the cellular protein AMP-activated protein kinase (AMPK). We also observed increased AMPK activity in K1-expressing cells compared to EV following exposure to metabolic stress. Several reports suggest that AMPK signaling may contribute to tumor development by promoting cell survival. Our results suggest that KSHV K1 modulates cellular AMPK function to enhance the survival of KSHV-infected cells in order to promote viral persistence.

Bioactive effects of quercetin in the central nervous system: Focusing on the mechanisms of actions

Quercetin, a ubiquitous flavonoid that is widely distributed in plants is classified as a cognitive enhancer in traditional and oriental medicine. The protective effects of quercetin for the treatment of neurodegenerative disorders and cerebrovascular diseases have been demonstrated in both in vitro and in vivo studies. The free radical scavenging activity of quercetin has been well-documented, wherein quercetin has been observed to exhibit protective effects against oxidative stress mediated neuronal damage by modulating the expression of NRF-2 dependent antioxidant responsive elements, and attenuation of neuroinflammation by suppressing NF-κB signal transducer and activator of transcription-1 (STAT-1). Several in vitro and in vivo studies have also shown that quercetin destabilizes and enhances the clearance of abnormal protein such as beta- amyloid peptide and hyperphosphorlyated tau, the key pathological hallmarks of Alzheimer's disease. Quercetin enhances neurogenesis and neuronal longevity by modulating a broad number of kinase signaling cascades such as phophoinositide 3- kinase (P13-kinase), AKT/PKB tyrosine kinase and Protein kinase C (PKC). Quercetin has also been well reported for its ability to reverse cognitive impairment and memory enhancement during aging. The current review focuses on summarizing the recent findings on the neuroprotective effect of quercetin, its mechanism of action and its possible roles in the prevention of neurological disorders.

Clinical study in genital herpes: natural Gene-Eden-VIR/Novirin versus acyclovir, valacyclovir, and famciclovir

BACKGROUND

This paper reports the results of a clinical study that tested the effect of suppressive treatment with the botanical product Gene-Eden-VIR/Novirin on the number of genital herpes outbreaks. The results in this study were compared to those published in clinical studies of acyclovir, valacyclovir, and famciclovir.

METHODS

The framework was a retrospective chart review. The population included 139 participants. The treatment was one to four capsules of Gene-Eden-VIR/Novirin per day. The duration of treatment was 2-48 months. The study included three controls recommended by the US Food and Drug Administration (FDA): baseline, no treatment, and dose response.

RESULTS

The treatment decreased the number of outbreaks per year in 90.8% of the participants. The treatment also decreased the mean number of outbreaks per year from 7.27 and 5.5 in the control groups to 2.39 (P<0.0001 and P<0.001, respectively). The treated participants reported no adverse experiences. Out of the 15 tests that compared Gene-Eden-VIR/Novirin to the three drugs, Gene-Eden-VIR/Novirin had superior efficacy in eight tests, inferior efficacy in three tests, and comparable efficacy in four tests. Gene-Eden-VIR/Novirin also had superior safety.

CONCLUSION

The clinical study showed that the natural Gene-Eden-VIR/Novirin decreases the number of genital herpes outbreaks without any side effects. The study also showed that the clinical effects reported in this study are mostly better than those reported in the reviewed studies of acyclovir, valacyclovir, and famciclovir.