HSV-1 cellular model reveals links between aggresome formation and early step of Alzheimer's disease

Unveiling the Involvement of Herpes Simplex Virus-1 in Alzheimer's Disease: Possible Mechanisms and Therapeutic Implications

Viruses pose a significant challenge and threat to human health, as demonstrated by the current COVID-19 pandemic. Neurodegeneration, particularly in the case of Alzheimer's disease (AD), is significantly influenced by viral infections. AD is a neurodegenerative disease that affects people of all ages and poses a significant threat to millions of individuals worldwide. The precise mechanism behind its development is not yet fully understood; however, the emergence and advancement of AD can be hastened by various environmental factors, such as bacterial and viral infections. There has been a longstanding suspicion that the herpes simplex virus-1 (HSV-1) may have a role to play in the development or advancement of AD. Reactivation of HSV-1 could potentially lead to damage to neurons, either by direct means or indirectly by triggering inflammation. This article provides an overview of the connection between HSV-1 infections and immune cells (astrocytes, microglia, and oligodendrocytes) in the progression of AD. It summarizes recent scientific research on how HSV-1 affects neurons, which could potentially shed light on the clinical features and treatment options for AD. In addition, the paper has explored the impact of HSV-1 on neurons and its role in various aspects of AD, such as Aβ secretion, tau hyperphosphorylation, metabolic dysregulation, oxidative damage, apoptosis, and autophagy. It is believed that the immune response triggered by HSV-1 reactivation plays a role in the development of neurodegeneration in AD. Despite the lack of a cure for AD, researchers have made significant efforts to study the clinical and pathological aspects of the disease, identify biomarkers, and gain insight into its underlying causes. The goal is to achieve early diagnosis and develop treatments that can modify the progression of the disease. The current article discusses the most promising therapy for combating the viral impacts, which provides additional evidence for the frequent reactivations of latent HSV-1 in the AD brain. However, further research is still required to establish the molecular and cellular mechanisms underlying the development of AD through the reactivation of HSV-1. This could potentially lead to new insights in drug development aimed at preventing HSV-1 reactivation and the subsequent development and progression of AD.

Association between herpesviruses and alzheimer's disease: a meta-analysis based on case-control studies

Herpesviruses infection has been found to be implicated in the etiology of Alzheimer's disease (AD). However, the results remain controversial. This systematic meta-analysis was aimed to evaluate the relationship between Herpesviruses infection and the risk of developing AD. Relevant literature was searched from five databases, including CNKI, PubMed, Web of Science, Embase, and Cochrane Library, to obtain case-control studies (published between the date of database establishment and February 2025; no language restrictions) that compared the Herpesviruses positivity in AD patients and healthy controls. Among all existing studies, there are more abundant published case-control studies on the relationship between HSV-1, HCMV and Alzheimer's disease. Therefore, we chose these two viruses to further explore their association with Alzheimer's disease. The quality of the included studies was evaluated by the NOS scale. The Review Manager 5.3 software was used to calculate the odds ratio (OR) and 95% confidence interval (95% CI) for meta-analysis. Publication bias was investigated using the funnel plots, Begg's and Egger's publication bias plots. Twenty-one eligible studies were included to investigate the association between HSV-1 and AD. The results of the meta-analysis indicated that HSV-1 infection is a risk factor for AD (OR = 1.39, 95% CI = (1.14-1.69), P < 0.05)). In the subgroup analysis, the pooled ORs of HSV-1 infection associated with AD were 1.28 (95% CI: 0.74-2.22) in literature prior to 2010;1.44 (95% CI: 1.14-1.82) in literature after 2010; 1.27(95% CI: 1.01-1.60) in studies from Europe; 1.22(95% CI: 0.66-2.27) in studies from North America;1.89 (95% CI: 1.19-3.02) in studies from Asia; 1.38 (95% CI: 1.10-1.74) in the clinical diagnosis group; 1.52 (95% CI: 0.84-2.74) in the autopsy group. The pooled OR of APOE4 positivity and AD risk was 5.51 (95% CI: 4.33-7.01). The association between HCMV and AD was analyzed in seven studies. The pooled result showed that HCMV infection is not a risk factor for AD (OR = 0.83, 95% CI = 0.63-1.09). Our latest meta-analysis suggests that HSV-1 infection is a risk factor for the risk of AD. Therefore, anti-HSV-1 infection can serve as a potential therapeutic strategy for control of AD incidence. There is insufficient evidence to support association between HCMV and AD.

Porphyromonas gingivalis: a potential trigger of neurodegenerative disease

Porphyromonas gingivalis (P. gingivalis) is a gram-negative bacterium and the main causative agent of periodontitis, a disease closely associated with the development of periodontal disease. The progression of periodontitis, a chronic infectious disease, is intricately linked to the inflammatory immune response. Inflammatory cytokines act on periodontal tissues via immunomodulation, resulting in the destruction of the periodontal tissue. Recent studies have established connections between periodontitis and various systemic diseases, including cardiovascular diseases, tumors, and neurodegenerative diseases. Neurodegenerative diseases are neurological disorders caused by immune system dysfunction, including Alzheimer's and Parkinson's diseases. One of the main characteristics of neurodegenerative diseases is an impaired inflammatory response, which mediates neuroinflammation through microglial activation. Some studies have shown an association between periodontitis and neurodegenerative diseases, with P. gingivalis as the primary culprit. P. gingivalis can cross the blood-brain barrier (BBB) or mediate neuroinflammation and injury through a variety of pathways, including the gut-brain axis, thereby affecting neuronal growth and survival and participating in the onset and progression of neurodegenerative diseases. However, comprehensive and systematic summaries of studies on the infectious origin of neurodegenerative diseases are lacking. This article reviews and summarizes the relationship between P. gingivalis and neurodegenerative diseases and its possible regulatory mechanisms. This review offers new perspectives into the understanding of neurodegenerative disease development and highlights innovative approaches for investigating and developing tailored medications for treating neurodegenerative conditions, particularly from the viewpoint of their association with P. gingivalis.

Inflammatory signaling pathways in Alzheimer's disease: Mechanistic insights and possible therapeutic interventions

The complex pathophysiology of Alzheimer's disease (AD) poses challenges for the development of therapies. Recently, neuroinflammation has been identified as a key pathogenic mechanism underlying AD, while inflammation has emerged as a possible target for the management and prevention of AD. Several prior studies have demonstrated that medications modulating neuroinflammation might lessen AD symptoms, mostly by controlling neuroinflammatory signaling pathways such as the NF-κB, MAPK, NLRP3, etc, and their respective signaling cascade. Moreover, targeting these inflammatory modalities with inhibitors, natural products, and metabolites has been the subject of intensive research because of their anti-inflammatory characteristics, with many studies demonstrating noteworthy pharmacological capabilities and potential clinical applications. Therefore, targeting inflammation is considered a promising strategy for treating AD. This review comprehensively elucidates the neuroinflammatory mechanisms underlying AD progression and the beneficial effects of inhibitors, natural products, and metabolites in AD treatment.

Recent advances in discovery and functional analysis of the small proteins and microRNA expressed by polyomaviruses

The polyomavirus family consists of a highly diverse group of small DNA viruses isolated from various species, including humans. Some family members have been used as model systems to understand the fundamentals of modern biology. After the discovery of the first two human polyomaviruses (JC virus and BK virus) during the early 1970s, their current number reached 14 today. Some family members cause considerably severe human diseases, including polyomavirus-associated nephropathy (PVAN), progressive multifocal leukoencephalopathy (PML), trichodysplasia spinulosa (TS) and Merkel cell carcinoma (MCC). Polyomaviruses encode universal regulatory and structural proteins, but some members express additional virus-specific proteins and microRNA, which significantly contribute to the viral biology, cell transformation, and perhaps progression of the disease that they are associated with. In the current review, we summarized the recent advances in discovery, and functional and structural analysis of those viral proteins and microRNA.

The fate of neuronal synapse homeostasis in aging, infection, and inflammation

Neuroplasticity is the brain's ability to reorganize and modify its neuronal connections in response to environmental stimuli, experiences, learning, and disease processes. This encompasses a variety of mechanisms, including changes in synaptic strength and connectivity, the formation of new synapses, alterations in neuronal structure and function, and the generation of new neurons. Proper functioning of synapses, which facilitate neuron-to-neuron communication, is crucial for brain activity. Neuronal synapse homeostasis, which involves regulating and maintaining synaptic strength and function in the central nervous system (CNS), is vital for this process. Disruptions in synaptic balance, due to factors like inflammation, aging, or infection, can lead to impaired brain function. This review highlights the main aspects and mechanisms underlying synaptic homeostasis, particularly in the context of aging, infection, and inflammation.

Multifaceted Role of Specialized Neuropeptide-Intensive Neurons on the Selective Vulnerability to Alzheimer's Disease in the Human Brain

Regarding Alzheimer's disease (AD), specific neuronal populations and brain regions exhibit selective vulnerability. Understanding the basis of this selective neuronal and regional vulnerability is essential to elucidate the molecular mechanisms underlying AD pathology. However, progress in this area is currently hindered by the incomplete understanding of the intricate functional and spatial diversity of neuronal subtypes in the human brain. Previous studies have demonstrated that neuronal subpopulations with high neuropeptide (NP) co-expression are disproportionately absent in the entorhinal cortex of AD brains at the single-cell level, and there is a significant decline in hippocampal NP expression in naturally aging human brains. Given the role of NPs in neuroprotection and the maintenance of microenvironments, we hypothesize that neurons expressing higher levels of NPs (HNP neurons) possess unique functional characteristics that predispose them to cellular abnormalities, which can manifest as degeneration in AD with aging. To test this hypothesis, multiscale and spatiotemporal transcriptome data from ~1900 human brain samples were analyzed using publicly available datasets. The results indicate that HNP neurons experienced greater metabolic burden and were more prone to protein misfolding. The observed decrease in neuronal abundance during stages associated with a higher risk of AD, coupled with the age-related decline in the expression of AD-associated neuropeptides (ADNPs), provides temporal evidence supporting the role of NPs in the progression of AD. Additionally, the localization of ADNP-producing HNP neurons in AD-associated brain regions provides neuroanatomical support for the concept that cellular/neuronal composition is a key factor in regional AD vulnerability. This study offers novel insights into the molecular and cellular basis of selective neuronal and regional vulnerability to AD in human brains.

Recent advances in Alzheimer's disease: Mechanisms, clinical trials and new drug development strategies

Alzheimer's disease (AD) stands as the predominant form of dementia, presenting significant and escalating global challenges. Its etiology is intricate and diverse, stemming from a combination of factors such as aging, genetics, and environment. Our current understanding of AD pathologies involves various hypotheses, such as the cholinergic, amyloid, tau protein, inflammatory, oxidative stress, metal ion, glutamate excitotoxicity, microbiota-gut-brain axis, and abnormal autophagy. Nonetheless, unraveling the interplay among these pathological aspects and pinpointing the primary initiators of AD require further elucidation and validation. In the past decades, most clinical drugs have been discontinued due to limited effectiveness or adverse effects. Presently, available drugs primarily offer symptomatic relief and often accompanied by undesirable side effects. However, recent approvals of aducanumab (1) and lecanemab (2) by the Food and Drug Administration (FDA) present the potential in disrease-modifying effects. Nevertheless, the long-term efficacy and safety of these drugs need further validation. Consequently, the quest for safer and more effective AD drugs persists as a formidable and pressing task. This review discusses the current understanding of AD pathogenesis, advances in diagnostic biomarkers, the latest updates of clinical trials, and emerging technologies for AD drug development. We highlight recent progress in the discovery of selective inhibitors, dual-target inhibitors, allosteric modulators, covalent inhibitors, proteolysis-targeting chimeras (PROTACs), and protein-protein interaction (PPI) modulators. Our goal is to provide insights into the prospective development and clinical application of novel AD drugs.

Antiviral activity of temporin-1CEb analogues against gingival infection with herpes simplex virus type 1

Introduction

Oral herpes infections caused by herpes simplex virus type 1 (HSV-1) are one of the most common in the human population. Recently, they have been classified as an increasing problem in immunocompromised patients and those suffering from chronic inflammation of the oral mucosa and gums. Treatment mainly involves nucleoside analogues, such as acyclovir and its derivatives, which reduce virus replication and shedding. As drug-resistant strains of herpes emerge rapidly, there is a need for the development of novel anti-herpes agents. The aim of the study was to design an antiviral peptide, based on natural compounds, non-toxic to the host, and efficient against drug-resistant HSV-1. Here, we designed a lysine-rich derivative of amphibian temporin-1CEb conjugated to peptides penetrating the host cell membrane and examined their activity against HSV-1 infection of oral mucosa.

Methods

We assessed the antiviral efficiency of the tested compound in simple 2D cell models (VeroE6 and TIGKs cells) and a 3D organotypic model of human gingiva (OTG) using titration assay, qPCR, and confocal imaging. To identify the molecular mechanism of antiviral activity, we applied the Azure A metachromatic test, and attachment assays techniques. Toxicity of the conjugates was examined using XTT and LDH assays.

Results

Our results showed that temporin-1CEb analogues significantly reduce viral replication in oral mucosa. The mechanism of peptide analogues is based on the interaction with heparan sulfate, leading to the reduce attachment of HSV-1 to the cell membrane. Moreover, temporin-1CEb conjugates effectively penetrate the gingival tissue being effective against acyclovir-resistant strains. Collectively, we showed that temporin-1CEb can be regarded as a novel, naturally derived antiviral compound for HSV-1 treatment.

Multifaceted impact of specialized neuropeptide-intensive neurons on the selective vulnerability in Alzheimer's disease

INTRODUCTION

Widespread disruption of neuropeptide (NP) networks in Alzheimer's disease (AD) and disproportionate absence of neurons expressing high NP-producing, coined as HNP neurons, have been reported for the entorhinal cortex (EC) of AD brains. Hypothesizing that functional features of HNP neurons are involved in the early pathogenesis of AD, we aim to understand the molecular mechanisms underlying these observations.

METHODS

Multiscale and spatiotemporal transcriptomic analysis was used to investigate AD-afflicted and healthy brains. Our focus encompassed NP expression dynamics in AD, AD-associated NPs (ADNPs) trajectories with aging, and the neuroanatomical distribution of HNP neuron.

RESULTS

Findings include that 1) HNP neurons exhibited heightened metabolic needs and an upregulation of gene expressions linked to protein misfolding; 2) dysfunctions of ADNP production occurred in aging and mild cognitive decline; 3) HNP neurons co-expressing ADNPs were preferentially distributed in brain regions susceptible to AD.

DISCUSSION

We identified potential mechanisms that contribute to the selective vulnerability of HNP neurons to AD. Our results indicate that the functions of HNP neurons predispose them to oxidative stress and protein misfolding, potentially serving as inception sites for misfolded proteins in AD.

Non-Thermal Plasma Reduces HSV-1 Infection of and Replication in HaCaT Keratinocytes In Vitro

Herpes simplex virus type 1 (HSV-1) is a lifelong pathogen characterized by asymptomatic latent infection in the trigeminal ganglia (TG), with periodic outbreaks of cold sores caused by virus reactivation in the TG and subsequent replication in the oral mucosa. While antiviral therapies can provide relief from cold sores, they are unable to eliminate HSV-1. We provide experimental results that highlight non-thermal plasma (NTP) as a new alternative therapy for HSV-1 infection that would resolve cold sores faster and reduce the establishment of latent infection in the TG. Additionally, this study is the first to explore the use of NTP as a therapy that can both treat and prevent human viral infections. The antiviral effect of NTP was investigated using an in vitro model of HSV-1 epithelial infection that involved the application of NTP from two separate devices to cell-free HSV-1, HSV-1-infected cells, and uninfected cells. It was found that NTP reduced the infectivity of cell-free HSV-1, reduced viral replication in HSV-1-infected cells, and diminished the susceptibility of uninfected cells to HSV-1 infection. This triad of antiviral mechanisms of action suggests the potential of NTP as a therapeutic agent effective against HSV-1 infection.

Mechanistic insights into the role of herpes simplex virus 1 in Alzheimer's disease

Alzheimer's Disease (AD) is an aging-associated neurodegenerative disorder, threatening millions of people worldwide. The onset and progression of AD can be accelerated by environmental risk factors, such as bacterial and viral infections. Human herpesviruses are ubiquitous infectious agents that underpin numerous inflammatory disorders including neurodegenerative diseases. Published studies concerning human herpesviruses in AD imply an active role HSV-1 in the pathogenesis of AD. This review will summarize the current understanding of HSV-1 infection in AD and highlight some barriers to advance this emerging field.