Role of β-catenin and TCF/LEF family members in transcriptional activity of HIV in astrocytes

HIV-1 infection promotes neuroinflammation and neuron pathogenesis in novel microglia-containing cerebral organoids

Cerebral organoids (COs) are a valuable tool to study the intricate interplay between glial cells and neurons in brain development and disease, including HIV-associated neuroinflammation. We developed a novel approach to generate microglia containing COs (CO-iMs) by co-culturing hematopoietic progenitors and induced pluripotent stem cells. This approach allowed for the differentiation of microglia within the organoids concomitantly to the neuronal progenitors. CO- iMs exhibited higher efficiency in generation of CD45 + /CD11b + /Iba-1 + microglia cells compared to conventional COs with physiologically relevant proportion of microglia (∼7%). CO-iMs exhibited substantially higher expression of microglial homeostatic and sensome markers as well as markers for the complement cascade. CO-iMs showed susceptibility to HIV infection resulting in a significant increase in several pro-inflammatory cytokines/chemokines and compromised neuronal function, which were abrogated by addition of antiretrovirals. Thus, CO-iM is a robust model to decipher neuropathogenesis, neurological disorders, and viral infections of brain cells in a 3D culture system.

Chikungunya virus perturbs the Wnt/β-catenin signaling pathway for efficient viral infection

IMPORTANCE

Being obligate parasites, viruses use various host cell machineries in effectively replicating their genome, along with virus-encoded enzymes. In order to carry out infection and pathogenesis, viruses are known to manipulate fundamental cellular processes in cells and interfere with host gene expression. Several viruses interact with the cellular proteins involved in the Wnt/β-catenin pathway; however, reports regarding the involvement of protein components of the Wnt/β-catenin pathway in Chikungunya virus (CHIKV) infection are scarce. Additionally, there are currently no remedies or vaccines available for CHIKV. This is the first study to report that modulation of the Wnt/β-catenin pathway is crucial for effective CHIKV infection. These investigations deepen the understanding of the underlying mechanisms of CHIKV infection and offer new avenue for developing effective countermeasures to efficiently manage CHIKV infection.

Familial and syndromic forms of arachnoid cyst implicate genetic factors in disease pathogenesis

Arachnoid cysts (ACs) are the most common space-occupying lesions in the human brain and present significant challenges for clinical management. While most cases of ACs are sporadic, nearly 40 familial forms have been reported. Moreover, ACs are seen with increased frequency in multiple Mendelian syndromes, including Chudley-McCullough syndrome, acrocallosal syndrome, and autosomal recessive primary ciliary dyskinesia. These findings suggest that genetic factors contribute to AC pathogenesis. However, traditional linkage and segregation approaches have been limited in their ability to identify causative genes for ACs because the disease is genetically heterogeneous and often presents asymptomatically and sporadically. Here, we comprehensively review theories of AC pathogenesis, the genetic evidence for AC formation, and discuss a different approach to AC genomics that could help elucidate this perplexing lesion and shed light on the associated neurodevelopmental phenotypes seen in a significant subset of these patients.

HIV infection of non-classical cells in the brain

HIV-associated neurological disorders (HAND) affect up to 50% of people living with HIV (PLWH), even in the era of combination antiretroviral therapy (cART). HIV-DNA can be detected in the cerebral spinal fluid (CSF) of approximately half of aviremic ART-suppressed PLWH and its presence is associated with poorer neurocognitive performance. HIV DNA + and HIV RNA + cells have also been observed in postmortem brain tissue of individuals with sustained cART suppression. In this review, we provide an overview of how HIV invades the brain and HIV infection of resident brain glial cells (astrocytes and microglia). We also discuss the role of resident glial cells in persistent neuroinflammation and HAND in PLWH and their potential contribution to the HIV reservoir. HIV eradication strategies that target persistently infected glia cells will likely be needed to achieve HIV cure.

Chronic delta-9-tetrahydrocannabinol (THC) treatment counteracts SIV-induced modulation of proinflammatory microRNA cargo in basal ganglia-derived extracellular vesicles

BACKGROUND

Early invasion of the central nervous system (CNS) by human immunodeficiency virus (HIV) (Gray et al. in Brain Pathol 6:1-15, 1996; An et al. in Ann Neurol 40:611-6172, 1996), results in neuroinflammation, potentially through extracellular vesicles (EVs) and their micro RNAs (miRNA) cargoes (Sharma et al. in FASEB J 32:5174-5185, 2018; Hu et al. in Cell Death Dis 3:e381, 2012). Although the basal ganglia (BG) is a major target and reservoir of HIV in the CNS (Chaganti et al. in Aids 33:1843-1852, 2019; Mintzopoulos et al. in Magn Reson Med 81:2896-2904, 2019), whether BG produces EVs and the effect of HIV and/or the phytocannabinoid-delta-9-tetrahydrocannabinol (THC) on BG-EVs and HIV neuropathogenesis remain unknown.

METHODS

We used the simian immunodeficiency virus (SIV) model of HIV and THC treatment in rhesus macaques (Molina et al. in AIDS Res Hum Retroviruses 27:585-592, 2011) to demonstrate for the first time that BG contains EVs (BG-EVs), and that BG-EVs cargo and function are modulated by SIV and THC. We also used primary astrocytes from the brains of wild type (WT) and CX3CR1+/GFP mice to investigate the significance of BG-EVs in CNS cells.

RESULTS

Significant changes in BG-EV-associated miRNA specific to SIV infection and THC treatment were observed. BG-EVs from SIV-infected rhesus macaques (SIV EVs) contained 11 significantly downregulated miRNAs. Remarkably, intervention with THC led to significant upregulation of 37 miRNAs in BG-EVs (SIV-THC EVs). Most of these miRNAs are predicted to regulate pathways related to inflammation/immune regulation, TLR signaling, Neurotrophin TRK receptor signaling, and cell death/response. BG-EVs activated WT and CX3CR1+/GFP astrocytes and altered the expression of CD40, TNFα, MMP-2, and MMP-2 gene products in primary mouse astrocytes in an EV and CX3CR1 dependent manners.

CONCLUSIONS

Our findings reveal a role for BG-EVs as a vehicle with potential to disseminate HIV- and THC-induced changes within the CNS.

CD4dim CD8bright T Cells Home to the Brain and Mediate HIV Neuroinvasion

CD4^dim CD8^bright T cells are a mature population of CD8⁺ T cells that upon activation upregulate CD4 dimly on their surface. Expression of CD4 on these cells suggests that they can be an additional source of HIV neuroinvasion and persistence in the brain. We used HIV-infected NOD/SCID/IL-2rcγ^-/- (NSG) humanized mice to track CD4^dim CD8^bright T cell homing to the brain and define their role in HIV dissemination into the brain. We report here that CD4^dim CD8^bright T cells are found in the brain at a median frequency of 2.6% and in the spleen at median frequency of 7.6% of CD3⁺ T cells. In the brain, 10 to 20% of CD4^dim CD8^bright T cells contain integrated provirus, which is infectious as demonstrated by viral outgrowth assay. CD4^dim CD8^bright T cells in the brain exhibited significantly higher expression of the brain homing receptors CX3CR1 and CXCR3 in comparison to their single-positive CD8⁺ T cell counterpart. Blocking lymphocyte trafficking into the brain of humanized mice via anti-VLA4 and anti-LFA1 antibodies reduced CD4^dim CD8^bright T cell trafficking into the brain by 60% and diminished brain HIV proviral DNA by 72%. Collectively, our findings demonstrate that CD4^dim CD8^bright T cells can home to the brain and support productive HIV replication. These studies also reveal for the first time that CD4^dim CD8^bright T cells are capable of HIV neuroinvasion and are a reservoir for HIV. IMPORTANCE We report here a seminal finding of a novel population of T cells, termed CD4^dim CD8^bright T cells, that plays a role in HIV neuroinvasion and is a reservoir for HIV in the brain.

WNT/β-catenin Pathway: a Possible Link Between Hypertension and Alzheimer's Disease

PURPOSE OF REVIEW

Recent research has shown that older people with high blood pressure (BP), or hypertension, are more likely to have biomarkers of Alzheimer's disease (AD). Essential hypertension represents the most common cardiovascular disease worldwide and is thought to be responsible for about 13% of all deaths. People with essential hypertension who regularly take prescribed BP medications are half as likely to develop AD as those who do not take them. What then is the connection?

RECENT FINDINGS

We know that high BP can damage small blood vessels in the brain, affecting those parts that are responsible for memory and thinking. However, the link between AD and hypertension remains unclear. Recent advances in the field of molecular and cellular biology have revealed a downregulation of the canonical WNT/β-catenin pathway in both hypertension and AD. In AD, the glutamate transport function is decreased, a decrease that is associated with a loss of synapse and neuronal death. β-catenin signaling appears to act as a major regulator of glutamate transporters (EAAT and GS) expression and can be harnessed to remove excess glutamate in AD. This review focuses on the possible link between hypertension and AD through the decreased WNT/β-catenin which interacts with the glutamatergic pathway.

Wnt/β-Catenin Protects Lymphocytes from HIV-Mediated Apoptosis via Induction of Bcl-xL

HIV infection mediates the apoptosis of lymphocytes, the mechanism of which is multifaceted. Here, we evaluated the role of Wnt/β-catenin signaling in HIV-associated T cell apoptosis, as Wnt/β-catenin regulates the transcriptional activity of genes impacting apoptosis. We specifically investigated the role of the Wnt/β-catenin pathway in the HIV-associated apoptosis of CD4+ T cells and CD4dimCD8bright T cells, a population that is infected by HIV. We found that the induction of β-catenin, via a 6-bromoindirubin-3-oxime (BIO), significantly rescued HIV-infected CD4+ and CD4dimCD8bright T cells from apoptosis by >40−50%. Further, a small-molecule inhibitor of the Wnt/β-catenin pathway (PNU-74654) reversed BIO-mediated protection from HIV-associated apoptosis. BIO also induced Bcl-xL, an anti-apoptotic protein, and a target gene of Wnt/β-catenin, in CD4+ and CD4dimCD8bright T cells by approximately 3-fold. Inhibiting Bcl-xL by WEHI-539 abrogated β-catenin-mediated apoptotic protection in infected CD4+ and CD4dimCD8bright T cells. Collectively, these findings demonstrate that engaging Wnt/β-catenin signaling in HIV-infected T cells protects them from HIV-associated apoptosis by inducing Bcl-xL.

Single-Cell RNA-Sequencing: Astrocyte and Microglial Heterogeneity in Health and Disease

Astrocytes and microglia are non-neuronal cells that maintain homeostasis within the central nervous system via their capacity to regulate neuronal transmission and prune synapses. Both astrocytes and microglia can undergo morphological and transcriptomic changes in response to infection with human immunodeficiency virus (HIV). While both astrocytes and microglia can be infected with HIV, HIV viral proteins in the local environment can interact with and activate these cells. Given that both astrocytes and microglia play critical roles in maintaining neuronal function, it will be critical to have an understanding of their heterogeneity and to identify genes and mechanisms that modulate their responses to HIV. Heterogeneity may include a depletion or increase in one or more astrocyte or microglial subtypes in different regions of the brain or spine as well as the gain or loss of a specific function. Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool that can be used to characterise these changes within a given population. The use of this method facilitates the identification of subtypes and changes in cellular transcriptomes that develop in response to activation and various disease processes. In this review, we will examine recent studies that have used scRNA-seq to explore astrocyte and microglial heterogeneity in neurodegenerative diseases including Alzheimer’s disease and amyotrophic lateral sclerosis as well as in response to HIV infection. A careful review of these studies will expand our current understanding of cellular heterogeneity at homeostasis and in response to specific disease states.

Neuroinflammation in Schizophrenia: The Key Role of the WNT/β-Catenin Pathway

Schizophrenia is a very complex syndrome involving widespread brain multi-dysconnectivity. Schizophrenia is marked by cognitive, behavioral, and emotional dysregulations. Recent studies suggest that inflammation in the central nervous system (CNS) and immune dysfunction could have a role in the pathogenesis of schizophrenia. This hypothesis is supported by immunogenetic evidence, and a higher incidence rate of autoimmune diseases in patients with schizophrenia. The dysregulation of the WNT/β-catenin pathway is associated with the involvement of neuroinflammation in schizophrenia. Several studies have shown that there is a vicious and positive interplay operating between neuroinflammation and oxidative stress. This interplay is modulated by WNT/β-catenin, which interacts with the NF-kB pathway; inflammatory factors (including IL-6, IL-8, TNF-α); factors of oxidative stress such as glutamate; and dopamine. Neuroinflammation is associated with increased levels of PPARγ. In schizophrenia, the expression of PPAR-γ is increased, whereas the WNT/β-catenin pathway and PPARα are downregulated. This suggests that a metabolic-inflammatory imbalance occurs in this disorder. Thus, this research’s triptych could be a novel therapeutic approach to counteract both neuroinflammation and oxidative stress in schizophrenia.

β-catenin regulates HIV latency and modulates HIV reactivation

Latency is the main obstacle towards an HIV cure, with cure strategies aiming to either elicit or prevent viral reactivation. While these strategies have shown promise, they have only succeeded in modulating latency in a fraction of the latent HIV reservoir, suggesting that the mechanisms controlling HIV latency are not completely understood, and that comprehensive latency modulation will require targeting of multiple latency maintenance pathways. We show here that the transcriptional co-activator and the central mediator of canonical Wnt signaling, β-catenin, inhibits HIV transcription in CD4+ T cells via TCF-4 LTR binding sites. Further, we show that inhibiting the β-catenin pathway reactivates HIV in a primary TCM cell model of HIV latency, primary cells from cART-controlled HIV donors, and in CD4+ latent cell lines. β-catenin inhibition or activation also enhanced or inhibited the activity of several classes of HIV latency reversing agents, respectively, in these models, with significant synergy of β-catenin and each LRA class tested. In sum, we identify β-catenin as a novel regulator of HIV latency in vitro and ex vivo, adding new therapeutic targets that may be combined for comprehensive HIV latency modulation in HIV cure efforts.

Pharmacological suppression of glycogen synthase kinase-3 reactivates HIV-1 from latency via activating Wnt/β-catenin/TCF1 axis in CD4+ T cells

ABSTRACTHIV-1 latency posts a major obstacle for HIV-1 eradication. Currently, no desirable latency reversing agents (LRAs) have been implicated in the "Shock and Kill" strategy to mobilize the latently infected cells to be susceptible for clearance by immune responses. Identification of key cellular pathways that modulate HIV-1 latency helps to develop efficient LRAs. In this study, we demonstrate that the Wnt downstream β-catenin/TCF1 pathway is a crucial modulator for HIV-1 latency. The pharmacological activation of the β-catenin/TCF1 pathway with glycogen synthase kinase-3 (GSK3) inhibitors promoted transcription of HIV-1 proviral DNA and reactivated latency in CD4⁺ T cells; the GSK3 kinase inhibitor 6-bromoindirubin-3'-oxime (6-BIO)-induced HIV-1 reactivation was subsequently confirmed in resting CD4⁺ T cells from cART-suppressed patients and SIV-infected rhesus macaques. These findings advance our understanding of the mechanisms responsible for viral latency, and provide the potent LRA that can be further used in conjunction of immunotherapies to eradicate viral reservoirs.

Possible actions of cannabidiol in obsessive-compulsive disorder by targeting the WNT/β-catenin pathway

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent and distinctive obsessions and/or compulsions. The etiologies remain unclear. Recent findings have shown that oxidative stress, inflammation, and glutamatergic pathways play key roles in the causes of OCD. However, first-line therapies include cognitive-behavioral therapy but only 40% of the patients respond to this first-line therapy. Research for new treatment is mandatory. This review focuses on the potential effects of cannabidiol (CBD), as a potential therapeutic strategy, on OCD and some of the presumed mechanisms by which CBD provides its benefit properties. CBD medication downregulates GSK-3β, the main inhibitor of the WNT/β-catenin pathway. The activation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway and circadian rhythms dysregulation in OCD. Future prospective clinical trials could focus on CBD and its different and multiple interactions in OCD.

The role of Pannexin-1 channels and extracellular ATP in the pathogenesis of the human immunodeficiency virus

Only recently, the role of large ionic channels such as Pannexin-1 channels and Connexin hemichannels has been implicated in several physiological and pathological conditions, including HIV infection and associated comorbidities. These channels are in a closed stage in healthy conditions, but in pathological conditions including HIV, Pannexin-1 channels and Connexin hemichannels become open. Our data demonstrate that acute and chronic HIV infection induces channel opening (Pannexin and Connexin channels), ATP release into the extracellular space, and subsequent activation of purinergic receptors in immune and non-immune cells. We demonstrated that Pannexin and Connexin channels contribute to HIV infection and replication, the long-term survival of viral reservoirs, and comorbidities such as NeuroHIV. Here, we discuss the available data to support the participation of these channels in the HIV life cycle and the potential therapeutic approach to prevent HIV-associated comorbidities.

β-Catenin Restricts Zika Virus Internalization by Downregulating Axl

The latest outbreak of Zika virus (ZIKV) in the Americas was associated with significant neurologic complications, including microcephaly of newborns. We evaluated mechanisms that regulate ZIKV entry into human fetal astrocytes (HFAs). Astrocytes are key players in maintaining brain homeostasis. We show that the central mediator of canonical Wnt signaling, β-catenin, regulates Axl, a receptor for ZIKV infection of HFAs, at the transcriptional level. In turn, ZIKV inhibited β-catenin, potentially as a mechanism to overcome its restriction of ZIKV internalization through regulation of Axl. This was evident with three ZIKV strains tested but not with a laboratory-adapted strain which has a large deletion in its envelope gene. Finally, we show that β-catenin-mediated Axl-dependent internalization of ZIKV may be of increased importance for brain cells, as it regulated ZIKV infection of astrocytes and human brain microvascular cells but not kidney epithelial (Vero) cells. Collectively, our studies reveal a role for β-catenin in ZIKV infection and highlight a dynamic interplay between ZIKV and β-catenin to modulate ZIKV entry into susceptible target cells. IMPORTANCE ZIKV is an emerging pathogen with sporadic outbreaks throughout the world. The most recent outbreak in North America was associated with small brains (microcephaly) in newborns. We studied the mechanism(s) that may regulate ZIKV entry into astrocytes. Astrocytes are a critical resident brain cell population with diverse functions that maintain brain homeostasis, including neurogenesis and neuronal survival. We show that three ZIKV strains (and not a heavily laboratory-adapted strain with a large deletion in its envelope gene) require Axl for internalization. Most importantly, we show that β-catenin, the central mediator of canonical Wnt signaling, negatively regulates Axl at the transcriptional level to prevent ZIKV internalization into human fetal astrocytes. To overcome this restriction, ZIKV downregulates β-catenin to facilitate Axl expression. This highlights a dynamic host-virus interaction whereby ZIKV inhibits β-catenin to promote its internalization into human fetal astrocytes through the induction of Axl.

The T cell factor, pangolin, from Litopenaeus vannamei play a positive role in the immune responses against white spot syndrome virus infection

As a downstream interactor of β-catenin, Pangolin which is the homologous protein of the T cell factor/lymphoid enhancer factor (TCF/LEF) in vertebrates is less understood in the research field of immunity. In this study, two isoforms of Litopenaeus vannamei Pangolin (LvPangolin1 and LvPangolin2) were identified. Phylogenetic tree analysis revealed that all of the Pangolin proteins from invertebrates were represented the same lineage. The mRNA expression profiles of the LvPangolin1 and LvPangolin2 genes differed across different tissues. The expression of LvPangolin1 and the amount of LvPangolin1and LvPangolin2 combined (LvPangolinComb) were significantly increased in the haemocyte, intestine and gill but reduced in the hepatopancreas after white spot syndrome virus (WSSV) challenge. The inhibition of LvPangolin1 but not LvPangolinComb significantly reduced the survival rates of L. vannamei after WSSV infection, while significantly higher WSSV viral loads in both LvPangolin1-inhibited and LvPangolinComb-inhibited L. vannamei were observed. Knockdown of LvPangolin by RNAi could distinctly decrease the expression of antimicrobial peptide (AMP) genes and their related transcription factors. All of these results indicate that LvPangolin plays a positive role in the response to WSSV infection and that this may be mediated through regulating the immune signalling pathways which control the expression of AMPs with antiviral abilities.

A RNA-seq approach for exploring the protective effect of ginkgolide B on glutamate-induced astrocytes injury

ETHNOPHARMACOLOGICAL RELEVANCE

There is substantial experimental evidence to support the view that Ginkgo biloba L. (Ginkgoaceae), a traditional Chinese medicine known to treating stroke, has a protective effect on the central nervous system and significantly improves the cognitive dysfunction caused by disease, including alzheimer disease (AD), vascular dementia, and diabetic encephalopathy. Although a number of studies have reported that ginkgolide B (GB), a diterpenoid lactone compound extracted from Ginkgo biloba leaves, has neuroprotective effects, very little research has been performed to explore its potential pharmacological mechanism on astrocytes under abnormal glutamate (Glu) metabolism in the pathological environment of AD.

AIM OF THE STUDY

We investigated the protective effect and mechanism of GB on Glu-induced astrocytes injury.

METHODS

Astrocytes were randomly divided into the control group, Glu group, GB group, and GB + IWP-4 group.The CCK-8 assay was used to determine relative cell viability in vitro. Furthermore, RNA sequencing (RNA-seq) was performed to assess the preventive effects of GB in the Glu-induced astrocyte model and reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to validate the possible molecular mechanisms. The effects of GB on the Glu transporter and Glu-induced apoptosis of astrocytes were studied by RT-qPCR and western blot.

RESULTS

GB attenuated Glu-induced apoptosis in a concentration-dependent manner, while the Wnt inhibitor IWP-4 reversed the protective effect of GB on astrocytes. The RNA-seq results revealed 4,032 differential gene expression profiles; 3,491 genes were up-regulated, and 543 genes were down-regulated in the GB group compared with the Glu group. Differentially expressed genes involved in a variety of signaling pathways, including the Hippo and Wnt pathways have been associated with the development and progression of AD. RT-qPCR was used to validate 14 key genes, and the results were consistent with the RNA-seq data. IWP-4 inhibited the regulation of GB, disturbed the apoptosis protective effect on astrocytes, and promoted Glu transporter gene and protein expression caused by Glu.

CONCLUSION

Our findings demonstrate that GB may play a protective role in Glu-induced astrocyte injury by regulating the Hippo and Wnt pathways. GB was closely associated with the Wnt pathway by promoting expression of the Glu transporter and inhibiting Glu-induced injury in astrocytes.

Cannabidiol and the Canonical WNT/β-Catenin Pathway in Glaucoma

Glaucoma is a progressive neurodegenerative disease which constitutes the main frequent cause of irreversible blindness. Recent findings have shown that oxidative stress, inflammation and glutamatergic pathway play key roles in the causes of glaucoma. Recent studies have shown a down regulation of the WNT/β-catenin pathway in glaucoma, associated with overactivation of the GSK-3β signaling. WNT/β-catenin pathway is mainly associated with oxidative stress, inflammation and glutamatergic pathway. Cannabidiol (CBD) is a non-psychotomimetic phytocannabinoid derived from Cannabis sativa plant which possesses many therapeutic properties across a range of neuropsychiatric disorders. Since few years, CBD presents an increased interest as a possible drug in anxiolytic disorders. CBD administration is associated with increase of the WNT/β-catenin pathway and decrease of the GSK-3β activity. CBD has a lower affinity for CB1 but can act through other signaling in glaucoma, including the WNT/β-catenin pathway. CBD downregulates GSK3-β activity, an inhibitor of WNT/β-catenin pathway. Moreover, CBD was reported to suppress pro-inflammatory signaling and neuroinflammation, oxidative stress and glutamatergic pathway. Thus, this review focuses on the potential effects of cannabidiol, as a potential therapeutic strategy, on glaucoma and some of the presumed mechanisms by which this phytocannabinoid provides its possible benefit properties through the WNT/β-catenin pathway.

Integrated analysis of lncRNA, miRNA and mRNA profiles reveals potential lncRNA functions during early HIV infection

Background

Long noncoding RNAs (lncRNAs) can regulate gene expression in a cis-regulatory fashion or as “microRNA sponges”. However, the expression and functions of lncRNAs during early human immunodeficiency virus (HIV) infection (EHI) remain unclear.

Methods

3 HAART-naive EHI patients and 3 healthy controls (HCs) were recruited in this study to perform RNA sequencing and microRNA (miRNA) sequencing. The expression profiles of lncRNAs, mRNAs and miRNAs were obtained, and the potential roles of lncRNAs were analysed based on discovering lncRNA cis-regulatory target mRNAs and constructing lncRNA–miRNA–mRNA competing endogenous RNA (ceRNA) networks. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on 175 lncRNA-associated differentially expressed (DE) mRNAs to investigate the potential functions of DE lncRNAs in ceRNA networks.

Results

A total of 242 lncRNAs, 1240 mRNAs and 21 mature known miRNAs were determined as differentially expressed genes in HAART-naive EHI patients compared to HCs. Among DE lncRNAs, 44 lncRNAs were predicted to overlap with 41 target mRNAs, and 107 lncRNAs might regulate their nearby DE mRNAs. Two DE lncRNAs might regulate their cis-regulatory target mRNAs BTLA and ZAP70, respectively, which were associated with immune activation. In addition, the ceRNA networks comprised 160 DE lncRNAs, 21 DE miRNAs and 175 DE mRNAs. Seventeen DE lncRNAs were predicted to regulate HIF1A and TCF7L2, which are involved in the process of HIV-1 replication. Twenty DE lncRNAs might share miRNA response elements (MREs) with FOS, FOSB and JUN, which are associated with both immune activation and HIV-1 replication.

Conclusions

This study revealed that lncRNAs might play a critical role in HIV-1 replication and immune activation during EHI. These novel findings are helpful for understanding of the pathogenesis of HIV infection and provide new insights into antiviral therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02802-9.

Parkinson's Disease: Potential Actions of Lithium by Targeting the WNT/β-Catenin Pathway, Oxidative Stress, Inflammation and Glutamatergic Pathway

Parkinson's disease (PD) is one of the major neurodegenerative diseases (ND) which presents a progressive neurodegeneration characterized by loss of dopamine in the substantia nigra pars compacta. It is well known that oxidative stress, inflammation and glutamatergic pathway play key roles in the development of PD. However, therapies remain uncertain and research for new treatment is mandatory. This review focuses on the potential effects of lithium, as a potential therapeutic strategy, on PD and some of the presumed mechanisms by which lithium provides its benefit properties. Lithium medication downregulates GSK-3beta, the main inhibitor of the WNT/β-catenin pathway. The stimulation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway. Future prospective clinical trials could focus on lithium and its different and multiple interactions in PD.

Alzheimer's disease-like perturbations in HIV-mediated neuronal dysfunctions: understanding mechanisms and developing therapeutic strategies

Excessive exposure to toxic substances or chemicals in the environment and various pathogens, including viruses and bacteria, is associated with the onset of numerous brain abnormalities. Among them, pathogens, specifically viruses, elicit persistent inflammation that plays a major role in Alzheimer's disease (AD) as well as dementia. AD is the most common brain disorder that affects thought, speech, memory and ability to execute daily routines. It is also manifested by progressive synaptic impairment and neurodegeneration, which eventually leads to dementia following the accumulation of Aβ and hyperphosphorylated Tau. Numerous factors contribute to the pathogenesis of AD, including neuroinflammation associated with pathogens, and specifically viruses. The human immunodeficiency virus (HIV) is often linked with HIV-associated neurocognitive disorders (HAND) following permeation through the blood-brain barrier (BBB) and induction of persistent neuroinflammation. Further, HIV infections also exhibited the ability to modulate numerous AD-associated factors such as BBB regulators, members of stress-related pathways as well as the amyloid and Tau pathways that lead to the formation of amyloid plaques or neurofibrillary tangles accumulation. Studies regarding the role of HIV in HAND and AD are still in infancy, and potential link or mechanism between both is not yet established. Thus, in the present article, we attempt to discuss various molecular mechanisms that contribute to the basic understanding of the role of HIV-associated neuroinflammation in AD and HAND. Further, using numerous growth factors and drugs, we also present possible therapeutic strategies to curb the neuroinflammatory changes and its associated sequels.

Negative regulation of IL-8 in human astrocytes depends on β-catenin while positive regulation is mediated by TCFs/LEF/ATF2 interaction

Expression of cytokines/chemokines is tightly regulated at the transcription level. This is crucial in the central nervous system to maintain neuroimmune homeostasis. IL-8 a chemoattractant, which recruits neutrophils, T cells, and basophils into the brain in response to inflammation and/or injury is secreted predominantly by neurons, microglia, and astrocytes. Here, we investigated the mechanism by which astrocytes regulate IL-8 expression. We demonstrate that while β-catenin negatively regulated IL-8 transcription, its canonical transcriptional partners, members of the TCF/LEF transcription factors (TCF1, TCF3, TCF4 and LEF1) and Activating transcription factor 2 (ATF2) positively regulated IL-8 transcription. We further identified a putative TCF/LEF binding site at -175nt close to the minimal transcription region on the IL-8 promoter, mutation of which caused a significant reduction in IL-8 promoter activity. Chromatin immunoprecipitation demonstrated binding of TCF1, TCF4, LEF1 and ATF2 on the IL-8 promoter suggesting that TCFs/LEF partner with ATF2 to induce IL-8 transcription. These findings demonstrate a novel role for β-catenin in suppression of IL-8 expression and for TCFs/LEF/ATF2 in inducing IL-8. These findings reveal a unique mechanism by which astrocytes tightly regulate IL-8 expression.

β-Catenin Regulates Wound Healing and IL-6 Expression in Activated Human Astrocytes

Reactive astrogliosis is prominent in most neurodegenerative disorders and is often associated with neuroinflammation. The molecular mechanisms regulating astrocyte-linked neuropathogenesis during injury, aging and human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) are not fully understood. In this study, we investigated the implications of the wingless type (Wnt)/β-catenin signaling pathway in regulating astrocyte function during gliosis. First, we identified that HIV-associated inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α induced mediators of the Wnt/β-catenin pathway including β-catenin and lymphoid enhancer-binding factor (LEF)-1 expression in astrocytes. Next, we investigated the regulatory role of β-catenin on primary aspects of reactive astrogliosis, including proliferation, migration and proinflammatory responses, such as IL-6. Knockdown of β-catenin impaired astrocyte proliferation and migration as shown by reduced cyclin-D1 levels, bromodeoxyuridine incorporation and wound healing. HIV-associated cytokines, IL-1β alone and in combination with TNF-α, strongly induced the expression of proinflammatory cytokines including C-C motif chemokine ligand (CCL)2, C-X-C motif chemokine ligand (CXCL)8 and IL-6; however, only IL-6 levels were regulated by β-catenin as demonstrated by knockdown and pharmacological stabilization. In this context, IL-6 levels were negatively regulated by β-catenin. To better understand this relationship, we examined the crossroads between β-catenin and nuclear factor (NF)-κB pathways. While NF-κB expression was significantly increased by IL-1β and TNF-α, NF-κB levels were not affected by β-catenin knockdown. IL-1β treatment significantly increased glycogen synthase kinase (GSK)-3β phosphorylation, which inhibits β-catenin degradation. Further, pharmacological inhibition of GSK-3β increased nuclear translocation of both β-catenin and NF-κB p65 into the nucleus in the absence of any other inflammatory stimuli. HIV+ human astrocytes show increased IL-6, β-catenin and NF-κB expression levels and are interconnected by regulatory associations during HAND. In summary, our study demonstrates that HIV-associated inflammation increases β-catenin pathway mediators to augment activated astrocyte responses including migration and proliferation, while mitigating IL-6 expression. These findings suggest that β-catenin plays an anti-inflammatory role in activated human astrocytes during neuroinflammatory pathologies, such as HAND.

Astrocytes, HIV and the Glymphatic System: A Disease of Disrupted Waste Management?

The discovery of the glial-lymphatic or glymphatic fluid clearance pathway in the rodent brain led researchers to search for a parallel system in humans and to question the implications of this pathway in neurodegenerative diseases. Magnetic resonance imaging studies revealed that several features of the glymphatic system may be present in humans. In both rodents and humans, this pathway promotes the exchange of interstitial fluid (ISF) and cerebrospinal fluid (CSF) through the arterial perivascular spaces into the brain parenchyma. This process is facilitated in part by aquaporin-4 (AQP4) water channels located primarily on astrocytic end feet that abut cerebral endothelial cells of the blood brain barrier. Decreased expression or mislocalization of AQP4 from astrocytic end feet results in decreased interstitial flow, thereby, promoting accumulation of extracellular waste products like hyperphosphorylated Tau (pTau). Accumulation of pTau is a neuropathological hallmark in Alzheimer's disease (AD) and is accompanied by mislocalization of APQ4 from astrocyte end feet to the cell body. HIV infection shares many neuropathological characteristics with AD. Similar to AD, HIV infection of the CNS contributes to abnormal aging with altered AQP4 localization, accumulation of pTau and chronic neuroinflammation. Up to 30% of people with HIV (PWH) suffer from HIV-associated neurocognitive disorders (HAND), and changes in AQP4 may be clinically important as a contributor to cognitive disturbances. In this review, we provide an overview and discussion of the potential contributions of NeuroHIV to glymphatic system functions by focusing on astrocytes and AQP4. Although HAND encompasses a wide range of neurocognitive impairments and levels of neuroinflammation vary among and within PWH, the potential contribution of disruption in AQP4 may be clinically important in some cases. In this review we discuss implications for possible AQP4 disruption on NeuroHIV disease trajectory and how HIV may influence AQP4 function.

Canonical Wnts Mediate CD8+ T Cell Noncytolytic Anti-HIV-1 Activity and Correlate with HIV-1 Clinical Status

CD8⁺ T cells do not rely solely on cytotoxic functions for significant HIV control. Moreover, the noncytotoxic CD8⁺ T cell antiviral response is a primary mediator of natural HIV control such as that seen in HIV elite controllers and long-term nonprogressors that does not require combined antiretroviral therapy. In this study, we investigated the biological factors contributing to the noncytotoxic control of HIV replication mediated by primary human CD8⁺ T cells. We report that canonical Wnt signaling inhibits HIV transcription in an MHC-independent, noncytotoxic manner and that mediators of this pathway correlate with HIV controller clinical status. We show that CD8⁺ T cells express all 19 Wnts and CD8⁺ T cell-conditioned medium (CM) induced canonical Wnt signaling in infected recipient cells while simultaneously inhibiting HIV transcription. Antagonizing canonical Wnt activity in CD8⁺ T cell CM resulted in increased HIV transcription in infected cells. Further, Wnt2b expression was upregulated in HIV controllers versus viremic patients, and in vitro depletion of Wnt2b and/or Wnt9b from CD8⁺ CM reversed HIV inhibitory activity. Finally, plasma concentration of Dkk-1, an antagonist of canonical Wnt signaling, was higher in viremic patients with lower CD4 counts. This study demonstrates that canonical Wnt signaling inhibits HIV and significantly correlates with HIV controller status.

Molecular Mechanisms Underlying the Circadian Rhythm of Blood Pressure in Normotensive Subjects

PURPOSE OF REVIEW

Blood pressure (BP) follows a circadian rhythm (CR) in normotensive subjects. BP increases in the morning and decreases at night. This review aims at providing an up-to-date overview regarding the molecular mechanisms underlying the circadian regulation of BP.

RECENT FINDINGS

The suprachiasmatic nucleus (SCN) is the regulatory center for CRs. In SCN astrocytes, the phosphorylated glycogen synthase kinase-3β (pGSK-3β) also follows a CR and its expression reaches a maximum in the morning and decreases at night. pGSK-3β induces the β-catenin migration to the nucleus. During the daytime, the nuclear β-catenin increases the expression of the glutamate excitatory amino acid transporter 2 (EAAT2) and glutamine synthetase (GS). In SCN, EAAT2 removes glutamate from the synaptic cleft of glutamatergic neurons and transfers it to the astrocyte cytoplasm where GS converts glutamate into glutamine. Thus, glutamate decreases in the synaptic cleft. This decreases the stimulation of the glutamate receptors AMPA-R and NMDA-R located on glutamatergic post-synaptic neurons. Consequently, activation of NTS is decreased and BP increases. The opposite occurs at night. Despite several studies resulting from animal studies, the circadian regulation of BP appears largely controlled in normotensive subjects by the canonical WNT/β-catenin pathway involving the SCN, astrocytes, and glutamatergic neurons.

β-Catenin and TCFs/LEF signaling discordantly regulate IL-6 expression in astrocytes

Background

The Wnt/β-catenin signaling pathway is a prolific regulator of cell-to-cell communication and gene expression. Canonical Wnt/β-catenin signaling involves partnering of β-catenin with members of the TCF/LEF family of transcription factors (TCF1, TCF3, TCF4, LEF1) to regulate gene expression. IL-6 is a key cytokine involved in inflammation and is particularly a hallmark of inflammation in the brain. Astrocytes, specialized glial cells in the brain, secrete IL-6. How astrocytes regulate IL-6 expression is not entirely clear, although in other cells NFκB and C/EBP pathways play a role. We evaluated here the interface between β-catenin, TCFs/LEF and C/EBP and NF-κB in relation to IL-6 gene regulation in astrocytes.

Methods

We performed molecular loss and/or gain of function studies of β-catenin, TCF/LEF, NFκB, and C/EBP to assess IL-6 regulation in human astrocytes. Specifically, siRNA mediated target gene knockdown, cDNA over expression of target gene, and pharmacological agents for regulation of target proteins were used. IL-6 levels was evaluated by real time quantitative PCR and ELISA. We also cloned the IL-6 promoter under a firefly luciferase reporter and used bioinformatics, site directed mutagenesis, and chromatin immunoprecipitation to probe the interaction between β-catenin/TCFs/LEFs and IL-6 promoter activity.

Results

β-catenin binds to TCF/LEF to inhibits IL-6 while TCFs/LEF induce IL-6 transcription through interaction with ATF-2/SMADs. β-catenin independent of TCFs/LEF positively regulates C/EBP and NF-κB, which in turn activate IL-6 expression. The IL-6 promoter has two putative regions for TCFs/LEF binding, a proximal site located at -91 nt and a distal site at -948 nt from the transcription start site, both required for TCF/LEF induction of IL-6 independent of β-catenin.

Conclusion

IL-6 regulation in human astrocytes engages a discordant interaction between β-catenin and TCF/LEF. These findings are intriguing given that no role for β-catenin nor TCFs/LEF to date is associated with IL-6 regulation and suggest that β-catenin expression in astrocytes is a critical regulator of anti-inflammatory responses and its disruption can potentially mediate persistent neuroinflammation.

HIV infects astrocytes in vivo and egresses from the brain to the periphery

HIV invades the brain during acute infection. Yet, it is unknown whether long-lived infected brain cells release productive virus that can egress from the brain to re-seed peripheral organs. This understanding has significant implication for the brain as a reservoir for HIV and most importantly HIV interplay between the brain and peripheral organs. Given the sheer number of astrocytes in the human brain and their controversial role in HIV infection, we evaluated their infection in vivo and whether HIV infected astrocytes can support HIV egress to peripheral organs. We developed two novel models of chimeric human astrocyte/human peripheral blood mononuclear cells: NOD/scid-IL-2Rgc null (NSG) mice (huAstro/HuPBMCs) whereby we transplanted HIV (non-pseudotyped or VSVg-pseudotyped) infected or uninfected primary human fetal astrocytes (NHAs) or an astrocytoma cell line (U138MG) into the brain of neonate or adult NSG mice and reconstituted the animals with human peripheral blood mononuclear cells (PBMCs). We also transplanted uninfected astrocytes into the brain of NSG mice and reconstituted with infected PBMCs to mimic a biological infection course. As expected, the xenotransplanted astrocytes did not escape/migrate out of the brain and the blood brain barrier (BBB) was intact in this model. We demonstrate that astrocytes support HIV infection in vivo and egress to peripheral organs, at least in part, through trafficking of infected CD4+ T cells out of the brain. Astrocyte-derived HIV egress persists, albeit at low levels, under combination antiretroviral therapy (cART). Egressed HIV evolved with a pattern and rate typical of acute peripheral infection. Lastly, analysis of human cortical or hippocampal brain regions of donors under cART revealed that astrocytes harbor between 0.4–5.2% integrated HIV gag DNA and 2–7% are HIV gag mRNA positive. These studies establish a paradigm shift in the dynamic interaction between the brain and peripheral organs which can inform eradication of HIV reservoirs.

HIV latency and residual low-level HIV replication is a major obstacle towards an HIV cure. HIV infects the brain in acute disease yet it is unknown whether long lived-infected brain cells release productive virus that can egress from the brain to re-seed peripheral organs and whether astrocytes are productively infected in vivo. We demonstrate astrocyte-initiated HIV spread from the brain to the spleen and lymph nodes, likely through T cell trafficking out of CNS and into peripheral organs. Additionally, brain sections from patients on cART show HIV integration in astrocytes. Collectively, given that astrocytes constitute ~60% of brain cells and even with a conservative rate of infection at >3%, astrocytes can be a significant reservoir for HIV. As such, cure initiatives must consider the contribution of the CNS to ongoing HIV replication within and outside of the brain.

Morphine exposure exacerbates HIV-1 Tat driven changes to neuroinflammatory factors in cultured astrocytes

Despite antiretroviral therapy human immunodeficiency virus type-1 (HIV-1) infection results in neuroinflammation of the central nervous system that can cause HIV-associated neurocognitive disorders (HAND). The molecular mechanisms involved in the development of HAND are unclear, however, they are likely due to both direct and indirect consequences of HIV-1 infection and inflammation of the central nervous system. Additionally, opioid abuse in infected individuals has the potential to exacerbate HIV-comorbidities, such as HAND. Although restricted for productive HIV replication, astrocytes (comprising 40-70% of all brain cells) likely play a significant role in neuropathogenesis in infected individuals due to the production and response of viral proteins. The HIV-1 protein Tat is critical for viral transcription, causes neuroinflammation, and can be secreted from infected cells to affect uninfected bystander cells. The Wnt/β-catenin signaling cascade plays an integral role in restricting HIV-1 infection in part by negatively regulating HIV-1 Tat function. Conversely, Tat can overcome this negative regulation and inhibit β-catenin signaling by sequestering the critical transcription factor TCF-4 from binding to β-catenin. Here, we aimed to explore how opiate exposure affects Tat-mediated suppression of β-catenin in astrocytes and the downstream modulation of neuroinflammatory genes. We observed that morphine can potentiate Tat suppression of β-catenin activity in human astrocytes. In contrast, Tat mutants deficient in secretion, and lacking neurotoxic effects, do not affect β-catenin activity in the presence or absence of morphine. Finally, morphine treatment of astrocytes was sufficient to reduce the expression of genes involved in neuroinflammation. Examining the molecular mechanisms of how HIV-1 infection and opiate exposure exacerbate neuroinflammation may help us inform or predict disease progression prior to HAND development.

Beta-catenin inhibits bovine parainfluenza virus type 3 replication via innate immunity pathway

Background

Bovine parainfluenza virus type 3 (BPIV3) is one of the important viral respiratory agents associated with the bovine respiratory disease complex (BRDC) in cattle. Previous study has demonstrated that infection of BPIV3 causes innate immune response within the host cell. β-catenin is a key component of the Wnt/β-catenin signal pathway which is involved in the regulation of interferon-beta (IFN-β) transcription. Some viruses can activate while others can inhibit the Wnt/β-catenin signaling pathway. However, the role of β-catenin in BPIV3 infection remains unclear.

Results

Here we found that the expression of β-catenin mRNA was up-regulated and β-catenin protein was down-regulated after BPIV3 infection in MDBK cells. Moreover, it was confirmed that overexpression of β-catenin suppressed BPIV3 replication and knockdown of β-catenin promoted viral replication, suggesting that β-catenin inhibits BPIV3 replication. Furthermore, IFN-β signal pathway and virus titer analysis using the GSK3β inhibitor (LiCl) revealed that Wnt/β-catenin can serve as a mechanism to suppress virus replication in infected cells. The results indicated that LiCl promoted the expression and accumulation in the nucleus of β-catenin, which further promoted the expression of IFN-β and OSA1 and suppressed BPIV3 replication. Most importantly, BPIV3 down-regulating β-catenin protein expression was due to degradation of GSK3β mediated proteasome pathway.

Conclusions

In summary, we discovered the relationship between β-catenin and BPIV3 replication. These results provided further insight into the study of BPIV3 pathogenesis.

Riluzole: a therapeutic strategy in Alzheimer's disease by targeting the WNT/β-catenin pathway

Alzheimer's disease (AD) is a neurodegenerative disease, where the etiology remains unclear. AD is characterized by amyloid-(Aβ) protein aggregation and neurofibrillary plaques deposits. Oxidative stress and chronic inflammation have been suggested as causes of AD. Glutamatergic pathway dysregulation is also mainly associated with AD process. In AD, the canonical WNT/β-catenin pathway is downregulated. Downregulation of WNT/β-catenin, by activation of GSK-3β-induced Aβ, and inactivation of PI3K/Akt pathway involve oxidative stress in AD. The downregulation of the WNT/β-catenin pathway decreases the activity of EAAT2, the glutamate receptors, and leads to neuronal death. In AD, oxidative stress, neuroinflammation and glutamatergic pathway operate in a vicious circle driven by the dysregulation of the WNT/β-catenin pathway. Riluzole is a glutamate modulator and used as treatment in amyotrophic lateral sclerosis. Recent findings have highlighted its use in AD and its potential increase power on the WNT pathway. Nevertheless, the mechanism by which Riluzole can operate in AD remains unclear and should be better determine. The focus of our review is to highlight the potential action of Riluzole in AD by targeting the canonical WNT/β-catenin pathway to modulate glutamatergic pathway, oxidative stress and neuroinflammation.

Role of Astrocytic Dysfunction in the Pathogenesis of Parkinson's Disease Animal Models from a Molecular Signaling Perspective

Despite the fact that astrocytes are the most abundant glial cells, critical for brain function, few studies have dealt with their possible role in neurodegenerative diseases like Parkinson's disease (PD). This article explores relevant evidence on the involvement of astrocytes in experimental PD neurodegeneration from a molecular signaling perspective. For a long time, astrocytic proliferation was merely considered a byproduct of neuroinflammation, but by the time being, it is clear that astrocytic dysfunction plays a far more important role in PD pathophysiology. Indeed, ongoing experimental evidence suggests the importance of astrocytes and dopaminergic neurons' cross-linking signaling pathways. The Wnt-1 (wingless-type MMTV integration site family, member 1) pathway regulates several processes including neuron survival, synapse plasticity, and neurogenesis. In PD animal models, Frizzled (Fzd) neuronal receptors' activation by the Wnt-1 normally released by astrocytes following injuries leads to β-catenin-dependent gene expression, favoring neuron survival and viability. The transient receptor potential vanilloid 1 (TRPV1) capsaicin receptor also participates in experimental PD genesis. Activation of astrocyte TRPV1 receptors by noxious stimuli results in reduced inflammatory response and increased ciliary neurotrophic factor (CNTF) synthesis, which enhances neuronal survival and differentiation. Another major pathway involves IκB kinase (IKK) downregulation by ARL6ip5 (ADP-ribosylation-like factor 6 interacting protein 5, encoded by the cell differentiation-associated, JWA, gene). Typically, IKK releases the proinflammatory NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) molecule from its inhibitor. Therefore, by downregulating NF-κB inhibitor, ARL6ip5 promotes an anti-inflammatory response. The evidence provided by neurotoxin-induced PD animal models guarantees further research on the neuroprotective potential of normalizing astrocyte function in PD.

Untreated Patients Dying With AIDS Have Loss of Neocortical Neurons and Glia Cells

Untreated human immunodeficiency virus (HIV) depletes its host CD4 cells, ultimately leading to acquired immunodeficiency syndrome (AIDS). In brain, the HIV confines itself to astrocytes and microglia, the resident brain macrophages, but does not infect oligodendrocytes and neurons. Nonetheless, cognitive symptoms associated with HIV and AIDS are attributed to loss of axons and white matter damage. We used design-based stereology to estimate the numbers of neocortical neurons and glial cells (astrocytes, oligodendrocytes, and microglia), in a series of 12 patients dying with AIDS before the era of retroviral treatments, and in 13 age-matched control brains. Relative to the control material, there was a 19% loss of neocortical neuron (p = 0.04) and a 29% reduction of oligodendrocytes (p = 0.003) in the patients with AIDS, whereas astrocyte and microglia numbers did not differ between patients and controls. Furthermore, we saw a 17% reduction in mean hemispheric volume in the AIDS group (p = 0.0015), which was driven by neocortical and white matter loss (p < 0.05), while the archicortex, subcortical gray matter, and ventricular volumes were within normal limits. Our results confirm previous reports of neuronal loss in AIDS. The new finding of oligodendrocyte loss supports the proposal that HIV in the brain provokes demyelination and axonal dysfunction and suggests that remyelination treatment strategies may be beneficial to patients suffering from HIV-associated neurocognitive deficits.

Wnt pathway: A mechanism worth considering in endocrine disrupting chemical action

Endocrine disrupting chemicals (EDCs) are defined as exogenous substances that can alter the development and functioning of the endocrine system. The Wnt signaling pathway is an evolutionarily conserved pathway consisting of proteins that transmit cell-to-cell receptors through cell surface receptors, regulating important aspects of cell migration, polarity, neural formation, and organogenesis, which determines the fate of the cell during embryonic development. Although the effects of EDCs have been studied in terms of many molecular mechanisms; because of its critical role in embryogenesis, the Wnt pathway is of special interest in EDC exposure. This review provides information about the effects of EDC exposure on the Wnt/β-catenin pathway focusing on studies on bisphenol A, di-(2-ethylhexyl) phthalate, diethylstilbestrol, cadmium, and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Prevalence and determinants of HIV shedding in breast milk during continued breastfeeding among Zambian mothers not on antiretroviral treatment (ART): A cross-sectional study

The risk of postnatal HIV transmission exists throughout the breastfeeding period. HIV shedding in breast milk beyond six months has not been studied extensively. The aim of this study was to determine prevalence and determinants of HIV shedding in breast milk during continued breastfeedingA cross-sectional study was nested in the PROMISE-PEP trial in Lusaka, Zambia to analyze breast milk samples collected from both breasts at week 38 post-partum (mid-way during continued breastfeeding). We measured concurrent HIV deoxyribonucleic acid (DNA) and HIV ribonucleic acid (RNA) as proxies for cell-associated HIV (CAV) and cell-free HIV (CFV) shedding in breast milk respectively. Participants' socio-demographic date, concurrent blood test results, sub clinical mastitis test results and contraceptive use data were available. Logistic regression models were used to identify determinants of HIV shedding in breast milk (detecting either CAV or CFV).The prevalence of HIV shedding in breast milk at 9 months post-partum was 79.4% (95%CI: 74.0 - 84.0). CAV only, CFV only and both CAV and CFV were detectable in 13.7%, 17.3% and 48.4% mothers, respectively. The odds of shedding HIV in breast milk decreased significantly with current use of combined oral contraceptives (AOR: 0.37; 95%CI: 0.17 - 0.83) and increased significantly with low CD4 count (AOR: 3.47; 95%CI: 1.23 - 9.80), unsuppressed plasma viral load (AOR: 6.27; 95%CI: 2.47 - 15.96) and severe sub-clinical mastitis (AOR: 12.56; 95%CI: 2.48 - 63.58).This study estimated that about 80% of HIV infected mothers not on ART shed HIV in breast milk during continued breastfeeding. Major factors driving this shedding were low CD4 count, unsuppressed plasma viral load and severe sub-clinical mastitis. The inverse relationship between breast milk HIV and use of combined oral contraceptives needs further clarification. Continued shedding of CAV may contribute to residual postnatal transmission of HIV in mothers on successful ART.

CD16+ monocytes give rise to CD103+RALDH2+TCF4+ dendritic cells with unique transcriptional and immunological features

Classical CD16^- vs intermediate/nonclassical CD16⁺ monocytes differ in their homing potential and biological functions, but whether they differentiate into dendritic cells (DCs) with distinct contributions to immunity against bacterial/viral pathogens remains poorly investigated. Here, we employed a systems biology approach to identify clinically relevant differences between CD16⁺ and CD16^- monocyte-derived DCs (MDDCs). Although both CD16⁺ and CD16^- MDDCs acquire classical immature/mature DC markers in vitro, genome-wide transcriptional profiling revealed unique molecular signatures for CD16⁺ MDDCs, including adhesion molecules (ITGAE/CD103), transcription factors (TCF7L2/TCF4), and enzymes (ALDH1A2/RALDH2), whereas CD16^- MDDCs exhibit a CDH1/E-cadherin⁺ phenotype. Of note, lipopolysaccharides (LPS) upregulated distinct transcripts in CD16⁺ (eg, CCL8, SIGLEC1, MIR4439, SCIN, interleukin [IL]-7R, PLTP, tumor necrosis factor [TNF]) and CD16^- MDDCs (eg, MMP10, MMP1, TGM2, IL-1A, TNFRSF11A, lysosomal-associated membrane protein 1, MMP8). Also, unique sets of HIV-modulated genes were identified in the 2 subsets. Further gene set enrichment analysis identified canonical pathways that pointed to "inflammation" as the major feature of CD16⁺ MDDCs at immature stage and on LPS/HIV exposure. Finally, functional validations and meta-analysis comparing the transcriptome of monocyte and MDDC subsets revealed that CD16⁺ vs CD16^- monocytes preserved their superior ability to produce TNF-α and CCL22, as well as other sets of transcripts (eg, TCF4), during differentiation into DC. These results provide evidence that monocyte subsets are transcriptionally imprinted/programmed with specific differentiation fates, with intermediate/nonclassical CD16⁺ monocytes being precursors for pro-inflammatory CD103⁺RALDH2⁺TCF4⁺ DCs that may play key roles in mucosal immunity homeostasis/pathogenesis. Thus, alterations in the CD16⁺ /CD16^- monocyte ratios during pathological conditions may dramatically influence the quality of MDDC-mediated immunity.

HIV-Associated Neurocognitive Impairment in the Modern ART Era: Are We Close to Discovering Reliable Biomarkers in the Setting of Virological Suppression?

The prevalence of the most severe forms of HIV-associated neurocognitive disorders (HAND) is decreasing due to worldwide availability and high efficacy of antiretroviral treatment (ART). However, several grades of HIV-related cognitive impairment persist with effective ART and remain a clinical concern for people with HIV (PWH). The pathogenesis of these cognitive impairments has yet to be fully understood and probably multifactorial. In PWH with undetectable peripheral HIV-RNA, the presence of viral escapes in cerebrospinal fluid (CSF) might explain a proportion of cases, but not all. Many other mechanisms have been hypothesized to be involved in disease progression, in order to identify possible therapeutic targets. As potential indicators of disease staging and progression, numerous biomarkers have been used to characterize and implicate chronic inflammation in the pathogenesis of neuronal injuries, such as certain phenotypes of activated monocytes/macrophages, in the context of persistent immune activation. Despite none of them being disease-specific, the correlation of several CSF cellular biomarkers to HIV-induced neuronal damage has been investigated. Furthermore, recent studies have been evaluating specific microRNA (miRNA) profiles in the CSF of PWH with neurocognitive impairment (NCI). The aim of the present study is to review the body of evidence on different biomarkers use in research and clinical settings, focusing on PWH on ART with undetectable plasma HIV-RNA.

Pharmaceutical Topical Delivery of Poorly Soluble Polyphenols: Potential Role in Prevention and Treatment of Melanoma

Melanoma is regarded as the fifth and sixth most common cancer in men and women, respectively, and it is estimated that one person dies from melanoma every hour in the USA. Unfortunately, the treatment of melanoma is difficult because of its aggressive metastasis and resistance to treatment. The treatment of melanoma continues to be a challenging issue due to the limitations of available treatments such as a low response rate, severe adverse reactions, and significant toxicity. Natural polyphenols have attracted considerable attention from the scientific community due to their chemopreventive and chemotherapeutic efficacy. It has been suggested that poorly soluble polyphenols such as curcumin, resveratrol, quercetin, coumarin, and epigallocatechin-3-gallate may have significant benefits in the treatment of melanoma due to their antioxidant, anti-inflammatory, antiproliferative, and chemoprotective efficacies. The major obstacles for the use of polyphenolic compounds are low stability and poor bioavailability. Numerous nanoformulations, including solid lipid nanoparticles, polymeric nanoparticles, micelles, and liposomes, have been formulated to enhance the bioavailability and stability, as well as the therapeutic efficacy of polyphenols. This review will provide an overview of poorly soluble polyphenols that have been reported to have antimetastatic efficacy in melanomas.

Keratin 6A gene silencing suppresses cell invasion and metastasis of nasopharyngeal carcinoma via the β‑catenin cascade

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer. This study aimed to study the mechanisms of ectopic keratin 6A (KRT6A) in NPC. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were performed to detect KRT6A levels in NPC cell lines (C666-1, 5-8F and SUNE-1) and a nasopharyngeal epithelial cell line (NP69, as a control). After SUNE-1 NPC cells had been silenced by KRT6A, cell viability, metastasis and invasion were determined using Cell Counting Kit-8, wound healing and Transwell assays, respectively. KRT6A levels, metastasis-associated factors and the Wnt/β-catenin pathway were measured using RT-qPCR and western blotting. It was demonstrated that KRT6A was upregulated in all detected NPC cells, among which KRT6A was the highest in SUNE-1 cells. In SUNE-1 cells, cell viability was inhibited at 24 and 48 h, and that cell metastasis and invasion were demonstrated to be suppressed by KRT6A silencing. Both the mRNA and protein levels of KRT6A, matrix metalloproteinase (MMP)-2, MMP-9, β-catenin, lymphoid enhancer binding factor 1 and T-cell specific factor 4 were reduced in the small interfering (si)KRT6A group. However, the results demonstrated that the levels of epithelial-cadherin and tissue inhibitor of metalloproteinase-2 (TIMP-2) were promoted in the siKRT6A group. The activation of the Wnt/β-catenin pathway by lithium chloride reversed the effect of si-KRT6A by modulating the expression of MMP-2/9 and TIMP2. It was observed that KRT6A silencing suppressed cell invasion and metastasis of NPC via the β-catenin cascade. Together these results provide important insights into a novel approach for the diagnosis and treatment of NPC.

Methamphetamine decreases K+ channel function in human fetal astrocytes by activating the trace amine-associated receptor type-1

Methamphetamine (Meth) is a potent and commonly abused psychostimulant. Meth alters neuron and astrocyte activity; yet the underlying mechanism(s) is not fully understood. Here we assessed the impact of acute Meth on human fetal astrocytes (HFAs) using whole-cell patch-clamping. We found that HFAs displayed a large voltage-gated K⁺ efflux (I_Kv ) through K_v /K_v -like channels during membrane depolarization, and a smaller K⁺ influx (I_kir ) via inward-rectifying K_ir /K_ir -like channels during membrane hyperpolarization. Meth at a 'recreational' (20 μM) or toxic/fatal (100 μM) concentration depolarized resting membrane potential (RMP) and suppressed I_Kv/Kv-like . These changes were associated with a decreased time constant (Ƭ), and mimicked by blocking the two-pore domain K⁺ (K_2P )/K_2P -like and K_v /K_v -like channels, respectively. Meth also diminished I_Kir/Kir-like , but only at toxic/fatal levels. Given that Meth is a potent agonist for the trace amine-associated receptor type-1 (TAAR1), and TAAR1-coupled cAMP/cAMP-activated protein kinase (PKA) cascade, we further evaluated whether the Meth impact on K⁺ efflux was mediated by this pathway. We found that antagonizing TAAR1 with N-(3-Ethoxyphenyl)-4-(1-pyrrolidinyl)-3-(trifluoromethyl)benzamide (EPPTB) reversed Meth-induced suppression of I_Kv/Kv-like ; and inhibiting PKA activity by H89 abolished Meth effects on suppressing I_Kv/Kv-like . Antagonizing TAAR1 might also attenuate Meth-induced RMP depolarization. Voltage-gated Ca²⁺ currents were not detected in HFAs. These novel findings demonstrate that Meth suppresses I_Kv/Kv-like by facilitating the TAAR1/G_s /cAMP/PKA cascade and altering the kinetics of K_v /K_v -like channel gating, but reduces K_2P /K_2P -like channel activity through other pathway(s), in HFAs. Given that Meth-induced decrease in astrocytic K⁺ efflux through K_2P /K_2P -like and K_v /K_v -like channels reduces extracellular K⁺ levels, such reduction could consequently contribute to a decreased excitability of surrounding neurons. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

mircoRNA-3162-3p is a potential biomarker to identify new infections in HIV-1-infected patients

BACKGROUND

Identification of new HIV infections (HIV incidence) is critical for monitoring AIDS epidemic and assessing the effectiveness of intervention measures. However, current methods for distinguishing new infections from newly diagnosed HIV-1 patients are still imperfect. We explored utilizing miRNAs as biomarker to identify HIV new infections.

METHODS

According to the HIV-1 status and the estimated duration of infection (EDI), we enrolled participants and divided them into three groups: healthy control, new infection (within 1 year), and old infection (longer than 1 year). Participants were assigned into screening set or validation set. miRNA microarray was performed in screening set and the differentially expressed miRNAs were screened out. The differentially expressed miRNAs were further confirmed in validation set and HIV-1 IIIB-MT2 cells infection system.

RESULTS

In screening set, 5 miRNAs including miR-1291, miR-3609, miR-3162-3p, miR-874-5p and miR-4258 were screened out for their differential expression in plasma among three groups. In validation set, down- trend of miR-3162-3p was validated from healthy control, new infection to old infection groups. In HIV-1 IIIB-MT2 system, the levels of miR-3162-3p also decreased along with infection duration in vitro. Sensitivity and specificity for miR-3162-3p to distinguish new infection from old infection were 100.0% and 71.43%, respectively, with the cut-off value of 0.916.

CONCLUSION

miR-3162-3p in plasma could be a potential microRNA biomarker to identify HIV new infections in HIV-1 infected patients.

Regulation of influenza virus replication by Wnt/β-catenin signaling

Wnt/β-catenin signaling is an essential pathway in cell cycle control. Dysregulation of the Wnt/β-catenin signaling pathway during viral infection has been reported. In this study, we examined the effect of modulating Wnt/β-catenin signaling during influenza virus infection. The activation of the Wnt/β-catenin pathway by Wnt3a increased influenza virus mRNA and virus production in in vitro in mouse lung epithelial E10 cells and mRNA expresson of influenza virus genes in vivo in the lungs of mice infected with influenza virus A/Puerto Rico/8/34. However, the inhibition of Wnt/β-catenin signaling by iCRT14 reduced virus titer and viral gene expression in human lung epithelial A549 cells and viral replication in primary mouse alveolar epithelial cells infected with different influenza virus strains. Knockdown of β-catenin also reduced viral protein expression and virus production. iCRT14 acts at the early stage of virus replication. Treatment with iCRT14 inhibited the expression of the viral genes (vRNA, cRNA and mRNA) evaluated in this study. The intraperitoneal administration of iCRT14 reduced viral load, improved clinical signs, and partially protected mice from influenza virus infection.

Multiple Inhibitory Factors Act in the Late Phase of HIV-1 Replication: a Systematic Review of the Literature

The use of lentiviral vectors for therapeutic purposes has shown promising results in clinical trials. The ability to produce a clinical-grade vector at high yields remains a critical issue. One possible obstacle could be cellular factors known to inhibit human immunodeficiency virus (HIV). To date, five HIV restriction factors have been identified, although it is likely that more factors are involved in the complex HIV-cell interaction. Inhibitory factors that have an adverse effect but do not abolish virus production are much less well described. Therefore, a gap exists in the knowledge of inhibitory factors acting late in the HIV life cycle (from transcription to infection of a new cell), which are relevant to the lentiviral vector production process. The objective was to review the HIV literature to identify cellular factors previously implicated as inhibitors of the late stages of lentivirus production. A search for publications was conducted on MEDLINE via the PubMed interface, using the keyword sequence "HIV restriction factor" or "HIV restriction" or "inhibit HIV" or "repress HIV" or "restrict HIV" or "suppress HIV" or "block HIV," with a publication date up to 31 December 2016. Cited papers from the identified records were investigated, and additional database searches were performed. A total of 260 candidate inhibitory factors were identified. These factors have been identified in the literature as having a negative impact on HIV replication. This study identified hundreds of candidate inhibitory factors for which the impact of modulating their expression in lentiviral vector production could be beneficial.

HIV and drug abuse mediate astrocyte senescence in a β-catenin-dependent manner leading to neuronal toxicity

Emerging evidence suggests that cell senescence plays an important role in aging-associated diseases including neurodegenerative diseases. HIV leads to a spectrum of neurologic diseases collectively termed HIV-associated neurocognitive disorders (HAND). Drug abuse, particularly methamphetamine (meth), is a frequently abused psychostimulant among HIV+ individuals and its abuse exacerbates HAND. The mechanism by which HIV and meth lead to brain cell dysregulation is not entirely clear. In this study, we evaluated the impact of HIV and meth on astrocyte senescence using in vitro and several animal models. Astrocytes constitute up to 50% of brain cells and play a pivotal role in marinating brain homeostasis. We show here that HIV and meth induce significant senescence of primary human fetal astrocytes, as evaluated by induction of senescence markers (β-galactosidase and p16^INK4A ), senescence-associated morphologic changes, and cell cycle arrest. HIV- and meth-mediated astrocyte senescence was also demonstrated in three small animal models (humanized mouse model of HIV/NSG-huPBMCs, HIV-transgenic rats, and in a meth administration rat model). Senescent astrocytes in turn mediated neuronal toxicity. Further, we show that β-catenin, a pro-survival/proliferation transcriptional co-activator, is downregulated by HIV and meth in human astrocytes and this downregulation promotes astrocyte senescence while induction of β-catenin blocks HIV- and meth-mediated astrocyte senescence. These studies, for the first time, demonstrate that HIV and meth induce astrocyte senescence and implicate the β-catenin pathway as potential therapeutic target to overcome astrocyte senescence.

Mechanisms of HIV Neuropathogenesis: Role of Cellular Communication Systems

BACKGROUND

One of the major complications of Human Immunodeficiency Virus (HIV) infection is the development of HIV-Associated Neurocognitive Disorders (HANDs) in approximately 50-60% of HIV infected individuals. Despite undetectable viral loads in the periphery owing to anti-retroviral therapy, neuroinflammation and neurocognitive impairment are still prevalent in HIV infected individuals. Several studies indicate that the central nervous system (CNS) abnormalities observed in HIV infected individuals are not a direct effect of viral replication in the CNS, rather these neurological abnormalities are associated with amplification of HIV specific signals by unknown mechanisms. We propose that some of these mechanisms of damage amplification are mediated by gap junction channels, pannexin and connexin hemichannels, tunneling nanotubes and microvesicles/exosomes.

OBJECTIVE

Our laboratory and others have demonstrated that HIV infection targets cell to cell communication by altering all these communication systems resulting in enhanced bystander apoptosis of uninfected cells, inflammation and viral infection. Here we discuss the role of these communication systems in HIV neuropathogenesis.

CONCLUSION

In the current manuscript, we have described the mechanisms by which HIV "hijacks" these host cellular communication systems, leading to exacerbation of HIV neuropathogenesis, and to simultaneously promote the survival of HIV infected cells, resulting in the establishment of viral reservoirs.

Plasma dickkopf-related protein 1, an antagonist of the Wnt pathway, is associated with HIV-associated neurocognitive impairment

OBJECTIVE

Dickkopf-related protein 1 (DKK1) is a soluble antagonist of the Wningless (Wnt) pathway. It binds to and sequesters low-density lipoprotein receptor-related proteins 5/6 away from Wnts. Because the Wnt pathway regulates synaptic transmission and plasticity, we hypothesized that increased DKK1 would increase the risk for neurocognitive impairment (NCI) in HIV-positive (HIV) individuals. We evaluated, here, the relationship between plasma DKK1 and global NCI.

METHODS

Plasma samples and data from 41 HIV to 42 HIV adults were obtained from the University of California, San Diego, California, USA. Concentrations of DKK1 and a comparator protein, monocyte chemoattractant protein-1 (MCP-1), were quantified in plasma by immunoassay. All study participants completed a standardized comprehensive neuropsychological test battery and their performance was summarized using the global deficit score method.

RESULTS

A higher DKK1 level was associated with NCI among HIV participants (d = 0.63, P = 0.05), particularly among the 26 participants whose plasma HIV RNA level was suppressed (d = 0.74, P = 0.08). DKK1 level was not associated with NCI among HIV participants (P = 0.98). was not associated with NCI in either group. In HIV adults with suppressed plasma HIV RNA, a receiver operator characteristic curve identified that a DKK1 level of at least 735 pg/ml had a positive predictive value of 83.3% for a diagnosis of NCI. This association did not weaken after accounting for the effect of AIDS, nadir CD4 T-cell count, addictive drug use, or demographic characteristics.

CONCLUSION

DKK1 is a specific biomarker for NCI in HIV adults, implicating the Wnt pathway in HIV neuropathogenesis.

The Role of HIV Infection in Neurologic Injury

The central nervous system (CNS) is a very challenging HIV-1 sanctuary, in which HIV-1 replication is established early on during acute infection and can persist despite potent antiretroviral treatments. HIV-1 infected macrophages play a pivotal role acting as vehicles for HIV-1 to spread into the brain, and can be the major contributor of an early compartmentalization. HIV-1 infection in CNS may lead to a broad spectrum of neurological syndromes, such as dementia, mild neurocognitive disorders, and asymptomatic impairment. These clinical manifestations are caused by the release of neurotoxins from infected cells (mainly macrophages), and also by several HIV-1 proteins, able to activate cell-signaling involved in the control of cellular survival and apoptosis. This review is aimed at highlighting the virological aspects associated with the onset of neurocognitive disorders and at addressing the novel therapeutic approaches to stop HIV-1 replication in this critical sanctuary.

iTRAQ-based Proteomic Analysis of Porcine Kidney Epithelial PK15 cells Infected with Pseudorabies virus

Pseudorabies virus (PRV) is one of the most important pathogens of swine, resulting in severe economic losses to the pig industry. To improve our understanding of the host responses to PRV infection, we applied isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography-tandem mass spectrometry to quantitatively identify the differentially expressed cellular proteins in PRV-infected PK15 cells. In total, relative quantitative data were identified for 4333 proteins in PRV and mock- infected PK15 cells, among which 466 cellular proteins were differentially expressed, including 234 upregulated proteins and 232 downregulated proteins. Bioinformatics analysis disclosed that most of these differentially expressed proteins were involved in metabolic processes, cellular growth and proliferation, endoplasmic reticulum (ER) stress response, cell adhesion and cytoskeleton. Moreover, expression levels of four representative proteins, beta-catenin, STAT1, GRB2 and PCNA, were further confirmed by western blot analysis. This is the first attempt to analyze the protein profile of PRV-infected PK15 cells using iTRAQ technology, and our findings may provide valuable information to help understand the host response to PRV infection.

β-Catenin signaling positively regulates glutamate uptake and metabolism in astrocytes

Background

Neurological disorders have been linked to abnormal excitatory neurotransmission. Perturbations in glutamate cycling can have profound impacts on normal activity, lead to excitotoxicity and neuroinflammation, and induce and/or exacerbate impairments in these diseases. Astrocytes play a key role in excitatory signaling as they both clear glutamate from the synaptic cleft and house enzymes responsible for glutamate conversion to glutamine. However, mechanisms responsible for the regulation of glutamate cycling, including the main astrocytic glutamate transporter excitatory amino acid transporter 2 (EAAT2 or GLT-1 in rodents) and glutamine synthetase (GS) which catalyzes the ATP-dependent reaction of glutamate and ammonia into glutamine, remain largely undefined.

Methods

Gain and loss of function for β-catenin in human progenitor-derived astrocyte (PDAs) was used to assess EAAT2 and GS levels by PCR, western blot, luciferase reporter assays, and chromatin immunoprecipitation (ChIP). Further, morpholinos were stereotaxically injected into C57BL/6 mice and western blots measured the protein levels of β-catenin, GLT-1, and GS.

Results

β-Catenin, a transcriptional co-activator and the central mediator of Wnt/β-catenin signaling pathway, positively regulates EAAT2 and GS at the transcriptional level in PDAs by partnering with T cell factor 1 (TCF-1) and TCF-3, respectively. This pathway is conserved in vivo as the knockdown of β-catenin in the prefrontal cortex results in reduced GLT-1 and GS expression.

Conclusions

These studies confirm that β-catenin regulates key proteins responsible for excitatory glutamate neurotransmission in vitro and in vivo and reveal the therapeutic potential of β-catenin modulation in treating diseases with abnormal glutamatergic neurotransmission and excitotoxicity.

The Wnt pathway: a key network in cell signalling dysregulated by viruses

Viruses are obligate parasites dependent on host cells for survival. Viral infection of a cell activates a panel of pattern recognition receptors that mediate antiviral host responses to inhibit viral replication and dissemination. Viruses have evolved mechanisms to evade and subvert this antiviral host response, including encoding proteins that hijack, mimic and/or manipulate cellular processes such as the cell cycle, DNA damage repair, cellular metabolism and the host immune response. Currently, there is an increasing interest whether viral modulation of these cellular processes, including the cell cycle, contributes to cancer development. One cellular pathway related to cell cycle signalling is the Wnt pathway. This review focuses on the modulation of this pathway by human viruses, known to cause (or associated with) cancer development. The main mechanisms where viruses interact with the Wnt pathway appear to be through (i) epigenetic modification of Wnt genes; (ii) cellular or viral miRNAs targeting Wnt genes; (iii) altering specific Wnt pathway members, often leading to (iv) nuclear translocation of β-catenin and activation of Wnt signalling. Given that diverse viruses affect this signalling pathway, modulating Wnt signalling could be a generalised critical process for the initiation or maintenance of viral pathogenesis, with resultant dysregulation contributing to virus-induced cancers. Further study of this virus-host interaction may identify options for targeted therapy against Wnt signalling molecules as a means to reduce virus-induced pathogenesis and the downstream consequences of infection. Copyright © 2016 John Wiley & Sons, Ltd.