MicroRNA-373 facilitates HSV-1 replication through suppression of type I IFN response by targeting IRF1

Small RNA sequencing analysis reveals regulation of microRNA expression in Madin-Darby canine kidney epithelial cells infected with Canid alphaherpesvirus 1

Canid alphaherpesvirus 1 (CHV-1) infection can cause spontaneous abortions in pregnant dams, and in young puppies, fatal systemic infections are common. MicroRNAs (miRNAs) affect viral infection by binding to messenger RNAs, and inhibiting expression of host and/or viral genes. We conducted deep sequencing of small RNAs in CHV-1-infected and mock-infected Madin-Darby Canine Kidney (MDCK) epithelial cells, and detected sequences corresponding to 282 cellular miRNAs. Of these, 18 were significantly upregulated at 12 h post-infection, most of which were encoded on the X chromosome. We next quantified the mature forms of several of the miRNAs using stem loop RT-qPCR. Our results revealed a discordance between the levels of small RNAs corresponding to canine miRNAs, and levels of the corresponding mature miRNAs, which suggests a block in miRNA biogenesis in infected cells. Nevertheless, we identified several mature miRNAs that exhibited a statistically significant increase upon infection. These included cfa-miR-8908b, a miRNA of unknown function, and cfa-miR-146a, homologs of which target innate immune pathways and are known to play a role in other viral infections. Interestingly, ontology analysis predicted that cfa-miR-8908b targets factors involved in the ubiquitin-like protein conjugation pathway and peroxisome biogenesis among other cellular functions. This is the first study to evaluate changes in miRNA levels upon CHV-1 infection. Based on our findings, we developed a model whereby CHV-1 infection results in changes in levels of a limited number of cellular miRNAs that target elements of the host immune response, which may provide clues regarding novel therapeutic targets.

Modulation of lncRNA NEAT1 overturns the macrophages based immune response in M. tuberculosis infected patients via miR-373 regulation

There is a lack of studies which explore and clarify the interactions that occur between host macrophage and Mycobacterium tuberculosis with regard to microRNA such as LNCNEAT1 and miR-373. The current study determines the mechanisms involved in the control of M. tuberculosis infection by macrophage using LNCNEAT1 and miR-373. The researchers collected different samples from healthy individuals, pulmonary TB patients, and samples like hMDMs cells and H37Rv infected MTB to determine the concentrations of inflammatory factors. The impact of NEAT1 and miR-373 upon macrophages was analyzed in NEAT1-specific siRNA (si-NEAT1), NEAT1 over-expression vector (pcDNA3.1-NEAT1), miR-373 mimic, miR-373 inhibitor (anti-miR-373), and negative control, and macrophages infected with H37Ra. The results inferred that among pulmonary TB patients, NEAT1 got heavily expressed while the expression level of miR-373 was poor. The number of inflammatory factors with pulmonary TB was notably higher. This got further amplified in macrophages after being infected with H37Ra, while no such observations found for miR-373. During post-transfection, low concentration of inflammatory factors was observed while the cells in si-NEAT1 group got proliferated in low volume compared to both pcDNA3.1-NEAT1 group and NEAT1 negative control group. However, the capability of apoptosis was higher compared to the other two groups (p < 0.05). There was an increase observed in inflammatory factors as well as proliferation in anti-miR-373 group compared to miR-373 mimics and miR-373-negative control group while a significant decline was observed in apoptosis. LNCNEAT1 aggravated the number of inflammatory factors in macrophages that got infected with MTB while on the other end, it mitigated both phagocytosis as well as the cellular immunity of macrophages. In addition to this, it enhanced the proliferation of infected cells and inhibited apoptosis via targeted regulation of miR-373, thus resulting in the development of TB.

Potential diagnostic value of miRNAs in sexually transmitted infections

MiRNAs are small endogenous non-coding RNAs that have been demonstrated to be involved in post-transcriptional gene silencing, regulating a number of metabolic functions in the human body, including immune response, cellular physiology, organ development, angiogenesis, signaling, and other aspects. As popular molecules that have been studied in previous years, given their extensive regulatory functions, miRNAs hold considerable promise as non-invasive biomarkers. Sexually transmitted infections(STIs) are still widespread and have an adverse effect on individuals, communities, and society worldwide. miRNAs in the regulatory networks are generally involved in their molecular processes of formation and development. In this review, we discuss the value of miRNAs for the diagnosis of STIs.

Viral MicroRNAs in Herpes Simplex Virus 1 Pathobiology

Simplexvirus humanalpha1 (Herpes simplex virus type 1 [HSV-1]) infects millions of people globally, manifesting as vesiculo-ulcerative lesions of the oral or genital mucosa. After primary infection, the virus establishes latency in the peripheral neurons and reactivates sporadically in response to various environmental and genetic factors. A unique feature of herpesviruses is their ability to encode tiny noncoding RNAs called microRNA (miRNAs). Simplexvirus humanalpha1 encodes eighteen miRNA precursors that generate twentyseven different mature miRNA sequences. Unique Simplexvirus humanalpha1 miRNAs repertoire is expressed in lytic and latent stages and exhibits expressional disparity in various cell types and model systems, suggesting their key pathological functions. This review will focus on elucidating the mechanisms underlying the regulation of host-virus interaction by HSV-1 encoded viral miRNAs. Numerous studies have demonstrated sequence- specific targeting of both viral and host transcripts by Simplexvirus humanalpha1 miRNAs. While these noncoding RNAs predominantly target viral genes involved in viral life cycle switch, they regulate host genes involved in antiviral immunity, thereby facilitating viral evasion and lifelong viral persistence inside the host. Expression of Simplexvirus humanalpha1 miRNAs has been associated with disease progression and resolution. Systemic circulation and stability of viral miRNAs compared to viral mRNAs can be harnessed to utilize their potential as diagnostic and prognostic markers. Moreover, functional inhibition of these enigmatic molecules may allow us to devise strategies that have therapeutic significance to contain Simplexvirus humanalpha1 infection.

MicroRNAs in infectious diseases: potential diagnostic biomarkers and therapeutic targets

MicroRNAs (miRNAs) are conserved, short, non-coding RNAs that play a crucial role in the post-transcriptional regulation of gene expression. They have been implicated in the pathogenesis of cancer and neurological, cardiovascular, and autoimmune diseases. Several recent studies have suggested that miRNAs are key players in regulating the differentiation, maturation, and activation of immune cells, thereby influencing the host immune response to infection. The resultant upregulation or downregulation of miRNAs from infection influences the protein expression of genes responsible for the immune response and can determine the risk of disease progression. Recently, miRNAs have been explored as diagnostic biomarkers and therapeutic targets in various infectious diseases. This review summarizes our current understanding of the role of miRNAs during viral, fungal, bacterial, and parasitic infections from a clinical perspective, including critical functional mechanisms and implications for their potential use as biomarkers and therapeutic targets.

Combinatorial Effects of miRNAs in HSV-2 Infection of Macrophages: An In Silico and In Vitro Integration Approach

The rising issues of herpes simplex virus (HSV)-2 drug ramifications have encouraged the researchers to look for new and alternative approaches that pose minimum adversities in the host while efficiently reducing the HSV-2 infection. Although microRNAs (miRNAs), as unorthodox approaches, are gaining popularity due to eliciting highly reduced immunogenic reactions, their implications in HSV-2 research have been rarely explored. In this study, a pool of cellular miRNAs with significance in HSV-2-induced inflammatory and immune responses have been identified. Computationally recognizing the host targets of these miRNAs through network biology and machine learning, in vitro validation has been addressed along with the identification of their regulation in the HSV-2 infection. To signify the role of these identified miRNAs, they have been individually ectopically expressed in macrophages. The ectopic expression of the individual miRNAs was able to suppress HSV-2 viral gene expression. Taking a step forward, this study also highlights the Box-Behnken design-based combinatorial effect of ectopically expressed miRNAs on maximum suppression of HSV-2 infectivity. Therefore, the concentrations of each of the miRNAs optimized in a combination, predicted through expert systems biology tools were validated in vitro to not only recover the target expressions but also inhibit the HSV-2 infection in the macrophages. Overall, the study offers miRNAs as intriguing alternatives to commercially available medications against HSV-2. Moreover, the study illuminates the prophylactic potentiality of the miRNAs, which is significant since there are currently no vaccines available for HSV-2. Moving forward, the miRNAs are employed in an innovative strategy that incorporates intricate biological system models and in vitro confirmation methods to deliver a prospective combinatorial miRNA therapeutic against HSV-2 infection.

miRNAs in Herpesvirus Infection: Powerful Regulators in Small Packages

microRNAs are a class of small, single-stranded, noncoding RNAs that regulate gene expression. They can be significantly dysregulated upon exposure to any infection, serving as important biomarkers and therapeutic targets. Numerous human DNA viruses, along with several herpesviruses, have been found to encode and express functional viral microRNAs known as vmiRNAs, which can play a vital role in host-pathogen interactions by controlling the viral life cycle and altering host biological pathways. Viruses have also adopted a variety of strategies to prevent being targeted by cellular miRNAs. Cellular miRNAs can act as anti- or proviral components, and their dysregulation occurs during a wide range of infections, including herpesvirus infection. This demonstrates the significance of miRNAs in host herpesvirus infection. The current state of knowledge regarding microRNAs and their role in the different stages of herpes virus infection are discussed in this review. It also delineates the therapeutic and biomarker potential of these microRNAs in future research directions.

The Virus-Induced Upregulation of the miR-183/96/182 Cluster and the FoxO Family Protein Members Are Not Required for Efficient Replication of HSV-1

Herpes simplex virus 1 (HSV-1) expresses a large number of miRNAs, and their function is still not completely understood. In addition, HSV-1 has been found to deregulate host miRNAs, which adds to the complexity of the regulation of efficient virus replication. In this study, we comprehensively addressed the deregulation of host miRNAs by massive-parallel sequencing. We found that only miRNAs expressed from a single cluster, miR-183/96/182, are reproducibly deregulated during productive infection. These miRNAs are predicted to regulate a great number of potential targets involved in different cellular processes and have only 33 shared targets. Among these, members of the FoxO family of proteins were identified as potential targets for all three miRNAs. However, our study shows that the upregulated miRNAs do not affect the expression of FoxO proteins, moreover, these proteins were upregulated in HSV-1 infection. Furthermore, we show that the individual FoxO proteins are not required for efficient HSV-1 replication. Taken together, our results indicate a complex and redundant response of infected cells to the virus infection that is efficiently inhibited by the virus.

The Emerging Role of Non-Coding RNAs in the Regulation of Virus Replication and Resultant Cellular Pathologies

Non-coding RNAs, particularly lncRNAs and miRNAs, have recently been shown to regulate different steps in viral infections and induction of immune responses against viruses. Expressions of several host and viral lncRNAs have been found to be altered during viral infection. These lncRNAs can exert antiviral function via inhibition of viral infection or stimulation of antiviral immune response. Some other lncRNAs can promote viral replication or suppress antiviral responses. The current review summarizes the interaction between ncRNAs and herpes simplex virus, cytomegalovirus, and Epstein–Barr infections. The data presented in this review helps identify viral-related regulators and proposes novel strategies for the prevention and treatment of viral infection.

Biomimetic Nucleation of Metal-Organic Frameworks on Silk Fibroin Nanoparticles for Designing Core-Shell-Structured pH-Responsive Anticancer Drug Carriers

Silk fibroin (SF) is a biomacromolecule that can be assembled into nanostructures and induce biomimetic nucleation of inorganic materials. Zeolitic imidazolate framework-8 (ZIF-8), a metal-organic framework (MOF), can be dissolved selectively under acidic pH. Here, we integrated SF and ZIF-8 to develop novel drug carriers that selectively release drug in the acidic intracellular environment of cancer cells. Specifically, SF was assembled into nanoparticles (SF-NPs), which were then loaded with an antitumor drug, doxorubicin (DOX), to form DSF-NPs. Due to the SF-mediated organization of ZIF-8 precursors such as zinc ions, the DSF-NPs further templated the nucleation of ZIF-8 onto their surface to generate core-shell-structured NPs (termed DSF@Z-NPs) with ZIF-8 as a shell and DSF-NP as a core. We found that the DSF@Z-NPs, highly stable under neutral conditions, could be uptaken by breast cancer cells, release DOX selectively owing to dissolution of ZIF-8 shells in the acidic intracellular environment in a controlled manner, and induce cell apoptosis. We also confirmed that the DSF@Z-NPs could inhibit tumor growth more efficiently to reach a higher survival rate than their controls by inducing cell apoptosis in vivo. Our study suggests that SF and MOF could be combined to design a new type of cancer therapeutics.

Local Immune Control of Latent Herpes Simplex Virus Type 1 in Ganglia of Mice and Man

Herpes simplex virus type 1 (HSV-1) is a prevalent human pathogen. HSV-1 genomes persist in trigeminal ganglia neuronal nuclei as chromatinized episomes, while epithelial cells are typically killed by lytic infection. Fluctuations in anti-viral responses, broadly defined, may underlay periodic reactivations. The ganglionic immune response to HSV-1 infection includes cell-intrinsic responses in neurons, innate sensing by several cell types, and the infiltration and persistence of antigen-specific T-cells. The mechanisms specifying the contrasting fates of HSV-1 in neurons and epithelial cells may include differential genome silencing and chromatinization, dictated by variation in access of immune modulating viral tegument proteins to the cell body, and protection of neurons by autophagy. Innate responses have the capacity of recruiting additional immune cells and paracrine activity on parenchymal cells, for example via chemokines and type I interferons. In both mice and humans, HSV-1-specific CD8 and CD4 T-cells are recruited to ganglia, with mechanistic studies suggesting active roles in immune surveillance and control of reactivation. In this review we focus mainly on HSV-1 and the TG, comparing and contrasting where possible observational, interventional, and in vitro studies between humans and animal hosts.

Herpes Simplex Virus 1 Infection of Neuronal and Non-Neuronal Cells Elicits Specific Innate Immune Responses and Immune Evasion Mechanisms

Alphaherpesviruses (α-HV) are a large family of double-stranded DNA viruses which cause many human and animal diseases. There are three human α-HVs: Herpes Simplex Viruses (HSV-1 and HSV-2) and Varicella Zoster Virus (VZV). All α-HV have evolved multiple strategies to suppress or exploit host cell innate immune signaling pathways to aid in their infections. All α-HVs initially infect epithelial cells (primary site of infection), and later spread to infect innervating sensory neurons. As with all herpesviruses, α-HVs have both a lytic (productive) and latent (dormant) stage of infection. During the lytic stage, the virus rapidly replicates in epithelial cells before it is cleared by the immune system. In contrast, latent infection in host neurons is a life-long infection. Upon infection of mucosal epithelial cells, herpesviruses immediately employ a variety of cellular mechanisms to evade host detection during active replication. Next, infectious viral progeny bud from infected cells and fuse to neuronal axonal terminals. Here, the nucleocapsid is transported via sensory neuron axons to the ganglion cell body, where latency is established until viral reactivation. This review will primarily focus on how HSV-1 induces various innate immune responses, including host cell recognition of viral constituents by pattern-recognition receptors (PRRs), induction of IFN-mediated immune responses involving toll-like receptor (TLR) signaling pathways, and cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING). This review focuses on these pathways along with other mechanisms including autophagy and the complement system. We will summarize and discuss recent evidence which has revealed how HSV-1 is able to manipulate and evade host antiviral innate immune responses both in neuronal (sensory neurons of the trigeminal ganglia) and non-neuronal (epithelial) cells. Understanding the innate immune response mechanisms triggered by HSV-1 infection, and the mechanisms of innate immune evasion, will impact the development of future therapeutic treatments.

Downregulation of miR-296-3p by highly pathogenic porcine reproductive and respiratory syndrome virus activates the IRF1/TNF-α signaling axis in porcine alveolar macrophages

Porcine reproductive and respiratory syndrome virus (PRRSV, species Betaarterivirus suid 1 or 2) is a major pathogen affecting pigs on farms throughout the world. miR-296-3p is a multifunctional microRNA involved in the regulation of the inflammatory response in mice and humans. However, little is known about the biological functions of miR-296-3p in pigs. In this study, we used a highly pathogenic PRRSV-2 (species Betaarterivirus suid 2) strain to show that PRRSV infection robustly downregulates the expression of miR-296-3p in porcine alveolar macrophages (PAMs). Furthermore, we demonstrated that overexpression of miR-296-3p increases the replication of highly pathogenic (HP)-PRRSV in PAMs. Notably, the overexpression of miR-296-3p inhibited the induction of TNF-α, even with increased viral replication, compared with that in the HP-PRRSV-infected control group. We also demonstrated that miR-296-3p targets IRF1-facilitated viral infection and modulates the expression of TNF-α in PAMs during HP-PRRSV infection and that IRF1 regulates the expression of TNF-α by activating the TNF promoter via IRF1 response elements. In summary, these findings show that HP-PRRSV infection activates the IRF1/TNF-α signaling axis in PAMs by downregulating host miR-296-3p. This extends our understanding of the inflammatory response induced by HP-PRRSV infection.

Interferon Regulatory Factors IRF1 and IRF7 Directly Regulate Gene Expression in Bats in Response to Viral Infection

Bat cells and tissue have elevated basal expression levels of antiviral genes commonly associated with interferon alpha (IFNα) signaling. Here, we show Interferon Regulatory Factor 1 (IRF1), 3, and 7 levels are elevated in most bat tissues and that, basally, IRFs contribute to the expression of type I IFN ligands and high expression of interferon regulated genes (IRGs). CRISPR knockout (KO) of IRF 1/3/7 in cells reveals distinct subsets of genes affected by each IRF in an IFN-ligand signaling-dependent and largely independent manner. As the master regulators of innate immunity, the IRFs control the kinetics and maintenance of the IRG response and play essential roles in response to influenza A virus (IAV), herpes simplex virus 1 (HSV-1), Melaka virus/Pteropine orthoreovirus 3 Melaka (PRV3M), and Middle East respiratory syndrome-related coronavirus (MERS-CoV) infection. With its differential expression in bats compared to that in humans, this highlights a critical role for basal IRF expression in viral responses and potentially immune cell development in bats with relevance for IRF function in human biology.

MicroRNA-132-3p suppresses type I IFN response through targeting IRF1 to facilitate H1N1 influenza A virus infection

Increasing evidence has indicated that microRNAs (miRNAs) have essential roles in innate immune responses to various viral infections; however, the role of miRNAs in H1N1 influenza A virus (IAV) infection is still unclear. The present study aimed to elucidate the role and mechanism of miRNAs in IAV replication in vitro. Using a microarray assay, we analyzed the expression profiles of miRNAs in peripheral blood from IAV patients. It was found that miR-132-3p was significantly up-regulated in peripheral blood samples from IAV patients. It was also observed that IAV infection up-regulated the expression of miR-132-3p in a dose- and time-dependent manner. Subsequently, we investigated miR-132-3p function and found that up-regulation of miR-132-3p promoted IAV replication, whereas knockdown of miR-132-3p repressed replication. Meanwhile, overexpression of miR-132-3p could inhibit IAV triggered INF-α and INF-β production and IFN-stimulated gene (ISG) expression, including myxovirus protein A (MxA), 2′,5′-oligoadenylate synthetases (OAS), and double-stranded RNA-dependent protein kinase (PKR), while inhibition of miR-132-3p enhanced IAV triggered these effects. Of note, interferon regulatory factor 1 (IRF1), a well-known regulator of the type I IFN response, was identified as a direct target of miR-132-3p during HIN1 IAV infection. Furthermore, knockdown of IRF1 by si-IRF1 reversed the promoting effects of miR-132-3p inhibition on type I IFN response. Taken together, up-regulation of miR-132-3p promotes IAV replication by suppressing type I IFN response through its target gene IRF1, suggesting that miR-132-3p could represent a novel potential therapeutic target of IAV treatment.

miR-130b-3p regulates M1 macrophage polarization via targeting IRF1

Polarized macrophages can be broadly classified into classically activated macrophages (M1) and alternatively activated macrophages (M2) in response to the microenvironment signals. Interferon regulatory factor 1 (IRF1) has been demonstrated to play a critical role in macrophage polarization. However, the mechanisms underlying the regulation of IRF1 expression in macrophage polarization still remain unclear. In this study, IRF1 expression was significantly increased in interferon-γ (IFN-γ) and lipopolysaccharide (LPS)-treated RAW264.7 cells. Moreover, miR-130b-3p was decreased and negatively associated with Irf1 in M1 macrophages. miR-130b-3p repressed M1 polarization by inhibiting IRF1 and subsequently reducing the levels of the targets of IRF1, C-C motif chemokine ligand 5 (CCL5), C-X-C motif chemokine ligand 10 (CXCL10), inducible NO synthase (iNOS), and tumor necrosis factor (TNF). Consistent with these data, overexpressed miR-130b-3p in LPS-treated mice suppressed M1 macrophage polarization in lung macrophages and peritoneal macrophages by inhibiting Irf1 expression and alleviated the inflammation in mouse lung tissues. Furthermore, the predicted binding site between the Irf1 messenger RNA 3'-untranslated region (3'-UTR) and miR-130b-3p was confirmed by the dual-luciferase reporter assay. In conclusion, our research gave the first evidence that miR-130b-3p affected the polarization of M1 macrophages by directly inhibiting Irf1. The miR-130b-3p/IRF1 pathway may be a potential target for regulating macrophage polarization.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Downregulation of miR-155-5p facilitates enterovirus 71 replication through suppression of type I IFN response by targeting FOXO3/IRF7 pathway

Enterovirus 71 (EV71), the major cause of hand-foot-and-mouth disease (HFMD), has evolved diverse strategies to counter the type I interferon (IFN-I) response during infection. Recently, microRNAs have regulatory roles in host innate immune responses to viral infections; however, whether EV71 escapes the IFN-I antiviral response through regulation of miRNAs remains unclear. Using a microarray assay, microRNA-155-5p (miR-155-5p) was found to be significantly up-regulated in serum from patients with EV71 infection and the increased expression of miR-155-5p was further confirmed in vivo and in vitro in response to EV71 infection. miR-155-5p overexpression suppressed EV71 titers and VP1 protein level, while miR-155-5p inhibition had an opposite result. Moreover, we found that miR-155-5p overexpression enhanced EV71 triggered IFN I production and the expressions of IFN-stimulated genes (ISGs), while inhibition of miR-155-5p suppressed these processes. Furthermore, bioinformatics analysis and luciferase reporter assay demonstrated that miR-155-5p directly targeted forkhead box protein O3 (FOXO3) and negatively regulated FOXO3/IRF7 axis, an important regulatory pathway for type I IFN production during EV71 infection. Inhibition of FOXO3 reversed the effects of miR-155-5p inhibitor on EV71 replication and the type I IFN production. Importantly, in EV71 infection mice, agomir-155-5p injection resulted in a significant reduction of viral VP1 protein expressions in brain and lung tissues, increased IFN-α/β production and increased mice survival rate. In contrast, antagomir-155-5p enhanced EV71 induced these effects. Collectively, our study indicates that weaken miR-155-5p facilitates EV71 replication through suppression of type I IFN response by FOXO3/IRF7 pathway, thereby suggesting a novel strategy for developing effective antiviral therapy.

miR-26a Inhibits Feline Herpesvirus 1 Replication by Targeting SOCS5 and Promoting Type I Interferon Signaling

In response to viral infection, host cells activate various antiviral responses to inhibit virus replication. While feline herpesvirus 1 (FHV-1) manipulates the host early innate immune response in many different ways, the host could activate the antiviral response to counteract it through some unknown mechanisms. MicroRNAs (miRNAs) which serve as a class of regulatory factors in the host, participate in the regulation of the host innate immune response against virus infection. In this study, we found that the expression levels of miR-26a were significantly upregulated upon FHV-1 infection. Furthermore, FHV-1 infection induced the expression of miR-26a via a cGAS-dependent pathway, and knockdown of cellular cGAS significantly blocked the expression of miR-26a induced by poly (dA:dT) or FHV-1 infection. Next, we investigated the biological function of miR-26a during viral infection. miR-26a was able to increase the phosphorylation of STAT1 and promote type I IFN signaling, thus inhibiting viral replication. The mechanism study showed that miR-26a directly targeted host SOCS5. Knockdown of SOCS5 increased the phosphorylation of STAT1 and enhanced the type I IFN-mediated antiviral response, and overexpression of suppressor of the cytokine signalling 5 (SOCS5) decreased the phosphorylation of STAT1 and inhibited the type I IFN-mediated antiviral response. Meanwhile, with the knockdown of SOCS5, the upregulated expression of phosphorylated STAT1 and the anti-virus effect induced by miR-26a were significantly inhibited. Taken together, our data demonstrated a new strategy of host miRNAs against FHV-1 infection by enhancing IFN antiviral signaling.

Viral Infections and Interferons in the Development of Obesity

Obesity is now a prevalent disease worldwide and has a multi-factorial etiology. Several viruses or virus-like agents including members of adenoviridae, herpesviridae, slow virus (prion), and hepatitides, have been associated with obesity; meanwhile obese patients are shown to be more susceptible to viral infections such as during influenza and dengue epidemics. We examined the co-factorial role of viral infections, particularly of the persistent cases, in synergy with high-fat diet in induction of obesity. Antiviral interferons (IFNs), as key immune regulators against viral infections and in autoimmunity, emerge to be a pivotal player in the regulation of adipogenesis. In this review, we examine the recent evidence indicating that gut microbiota uphold intrinsic IFN signaling, which is extensively involved in the regulation of lipid metabolism. However, the prolonged IFN responses during persistent viral infections and obesogenesis comprise reciprocal causality between virus susceptibility and obesity. Furthermore, some IFN subtypes have shown therapeutic potency in their anti-inflammation and anti-obesity activity.

MEK1/2 Inhibitors Unlock the Constrained Interferon Response in Macrophages Through IRF1 Signaling

Macrophages are immune sentinels essential for pathogen recognition and immune defense. Nucleic acid-sensing toll-like receptors like TLR7 activate tailored proinflammatory and interferon responses in macrophages. Here we found that TLR7 activation constrained itself and other TLRs from inducing interferon response genes in macrophages through MAPK kinase 1/2 (MEK1/2)-dependent IRF1 inhibition. Downstream of the MEK1/2-ERK pathway, TLR7-activated macrophages induced interleukin-10 (IL-10), a signal transducer and activator of transcription 3 (STAT3) signaling axis, which constrained the expression of interferon response genes, immunomodulatory cytokines, and chemokines. Nevertheless, MEK1/2 inhibitors unlocked an IRF1-interferon signature response in an NF-κB-dependent manner. Deficiency in interferon regulatory factor 1 (Irf1) completely abrogated the interferon response and prevented the reprogramming of macrophages into an immunostimulatory phenotype. As a proof of concept, combination treatment with a TLR7 agonist and MEK1/2 inhibitor synergistically extended the survival of wild-type but not Irf1-deficient melanoma-bearing mice. In a retrospective study, higher expression of Irf1 and interferon response genes correlated with more favorable prognosis in patients with cutaneous melanoma. Our findings demonstrated how MEK1/2 inhibitor unlocks IRF1-mediated interferon signature response in macrophages, and the therapeutic potentials of combination therapy with MEK1/2 inhibitor and TLR7 agonist.

Analysis of the microRNA expression profiles in feline kidney cell line infected with feline panleukopenia virus

MicroRNAs (miRNAs) play crucial roles in post-transcriptional regulation of gene expression in many biological processes. Feline panleukopenia virus (FPV) is a highly infectious pathogen that can cause severe disease in pets, economically important animals and wildlife. In this study, miRNAs associated with FPV infection were identified using high-throughput sequencing. Our results showed that 673 known miRNAs and 278 novel miRNAs were identified and 57 significantly differential expression miRNAs were found post-FPV infection in feline kidney cell line. Stem-loop qRT-PCR was applied to validate the expression of the randomly selected miRNAs; the results were consistent with the sequencing data. Furthermore, the target genes of differential expression miRNAs were analyzed and predicated by GO and KEGG pathway. Altogether, our analysis provides a potential link between miRNA expression and the pathogenesis of FPV infection.

MicroRNAs in Neuroinflammation: Implications in Disease Pathogenesis, Biomarker Discovery and Therapeutic Applications

The central nervous system can respond to threat via the induction of an inflammatory response. Under normal circumstances this response is tightly controlled, however uncontrolled neuroinflammation is a hallmark of many neurological disorders. MicroRNAs are small non-coding RNA molecules that are important for regulating many cellular processes. The ability of microRNAs to modulate inflammatory signaling is an area of ongoing research, which has gained much attention in recent years. MicroRNAs may either promote or restrict inflammatory signaling, and either exacerbate or ameliorate the pathological consequences of excessive neuroinflammation. The aim of this review is to summarize the mode of regulation for several important and well-studied microRNAs in the context of neuroinflammation, including miR-155, miR-146a, miR-124, miR-21 and let-7. Furthermore, the pathological consequences of miRNA deregulation during disorders that feature neuroinflammation are discussed, including Multiple Sclerosis, Alzheimer’s disease, Parkinson’s disease, Prion diseases, Japanese encephalitis, Herpes encephalitis, ischemic stroke and traumatic brain injury. There has also been considerable interest in the use of altered microRNA signatures as biomarkers for these disorders. The ability to modulate microRNA expression may even serve as the basis for future therapeutic strategies to help treat pathological neuroinflammation.

MiR-155-5p modulates HSV-1 replication via the epigenetic regulation of SRSF2 gene expression

A previous study reported that miR-155-5p knockout mice were more resistant to herpes simplex virus type I (HSV-1) infection. However, the exact underlying molecular mechanism remains to be elucidated. Here, we demonstrated that HSV-1 infection upregulates miR-155-5p expression. By binding to the promoter of serine/arginine-rich splicing factor 2 (SRSF2), which is an important transcriptional activator of HSV-1 genes that was previously reported by our group, and altering the histone modification located near the transcription start site (TSS) of the SRSF2 gene, miR-155-5p promotes the transcription of the SRSF2 gene, ultimately increasing viral replication and viral gene expression. Our results provide insight for an understanding of the roles and molecular mechanism of miR-155-5p in HSV-1 replication and the epigenetic control of SRSF2 gene expression.

Depletion of MicroRNA-373 Represses the Replication of Hepatitis C Virus via Activation of Type 1 Interferon Response by Targeting IRF5

PURPOSE

Hepatitis C virus (HCV) poses a risk of chronic liver disease and threatens a significant number of people worldwide. MicroRNAs (miRNAs) are linked to the regulation of hepatocarcinogenesis. Although miR-373 is required for HCV infection, the underlying mechanisms of miR-373 involvement in HCV replication remain elusive.

MATERIALS AND METHODS

Quantitative reverse transcription PCR assays were performed to detect the abundances of miR-373 and HCV RNA either in Huh 7.5 cells or liver biopsy specimens with HCV infection. Luciferase assay was employed to probe the interactions between miR-373 and interferon regulatory factor 5 (IRF5). Western blot was conducted to investigate the effect of miR-373 and IRF5 on HCV replication and activation of type 1 interferon (IFN) response in JFH1-infected Huh 7.5 cells.

RESULTS

HCV infection appeared to be caused by increased miR-373 expression. Addition of miR-373 promoted HCV RNA expression, while miR-373 depletion led to an inhibitive effect on HCV replication. Concordantly, IRF5, as a direct target, was limited by miR-373 in JFH1-infected Huh 7.5 cells. In addition, introduction of IRF5 protected HCV replication in the presence of abundant miR-373. Furthermore, the miR-373-mediated inhibitory effect on type 1 IFN response was ablated following IRF5 accumulation.

CONCLUSION

miR-373 abrogation reduced HCV replication via activation of type 1 IFN responses by targeting IRF5 in JFH1-infected Huh 7.5 cells, suggesting a promising therapeutic for treating HCV infection.

Herpes Simplex Virus 1 Deregulation of Host MicroRNAs

Viruses utilize microRNAs (miRNAs) in a vast variety of possible interactions and mechanisms, apparently far beyond the classical understanding of gene repression in humans. Likewise, herpes simplex virus 1 (HSV-1) expresses numerous miRNAs and deregulates the expression of host miRNAs. Several HSV-1 miRNAs are abundantly expressed in latency, some of which are encoded antisense to transcripts of important productive infection genes, indicating their roles in repressing the productive cycle and/or in maintenance/reactivation from latency. In addition, HSV-1 also exploits host miRNAs to advance its replication or repress its genes to facilitate latency. Here, we discuss what is known about the functional interplay between HSV-1 and the host miRNA machinery, potential targets, and the molecular mechanisms leading to an efficient virus replication and spread.

LncRNA, miRNA and lncRNA-miRNA interaction in viral infection

Noncoding RNAs (ncRNAs) are key components of the transcriptome and play an important role in both normal biological activity and pathological processes such as viral infection and tumorigenesis. LncRNAs and miRNAs are the most important elements of ncRNAs and function as vital regulatory elements. Their complex regulatory relationship has therefore attracted a lot of attention. In this review, we address the generation, classification, and regulatory mechanisms of lncRNAs and miRNAs in the interaction between virus and host, focusing on their mutual regulation in viral replication and pathogenesis. In-depth analysis of the underlying mechanisms will provide new information for the prevention of viral infections and development of antiviral drugs.