MicroRNA-628-5p Facilitates Enterovirus 71 Infection by Suppressing TRAF3 Signaling

Cardiac miR-19a/19b was induced and hijacked by CVB3 to facilitate virus replication via targeting viral genomic RdRp-encoding region

Coxsackievirus B3 (CVB3) is one of the major pathogens of viral myocarditis, lacking specific anti-virus therapeutic options. Increasing evidence has shown an important involvement of the miR-17-92 cluster both in virus infection and cardiovascular development and diseases, while its role in CVB3-induced viral myocarditis remains unclear. In this study, we found that miR-19a and miR-19b were significantly up-regulated in heart tissues of CVB3-infected mice and exerted a significant facilitatory impact on CVB3 biosynthesis and replication, with a more pronounced effect observed in miR-19b, by targeting the encoding region of viral RNA-dependent RNA polymerase 3D (RdRp, 3Dpol) to increase viral genomic RNA stability. The virus-promoting effects were nullified by the synonymous mutations in the viral 3Dpol-encoding region, which corresponded to the seed sequence shared by miR-19a and miR-19b. In parallel, treatment with miR-19b antagomir not only resulted in a noteworthy suppression of CVB3 replication and infection in infected cells, but also demonstrated a significant reduction in the cardiac viral load of CVB3-infected mice, resulting in a considerable alleviation of myocarditis. Collectively, our study showed that CVB3-induced cardiac miR-19a/19b contributed to viral myocarditis via facilitating virus biosynthesis and replication, and targeting miR-19a/19b might represent a novel therapeutic target for CVB3-induced viral myocarditis.

EV-A71 Mechanism of Entry: Receptors/Co-Receptors, Related Pathways and Inhibitors

Enterovirus A71, a non-enveloped single-stranded (+) RNA virus, enters host cells through three stages: attachment, endocytosis and uncoating. In recent years, receptors/co-receptors anchored on the host cell membrane and involved in this process have been continuously identified. Among these, hSCARB-2 was the first receptor revealed to specifically bind to a definite site of the EV-A71 viral capsid and plays an indispensable role during viral entry. It actually acts as the main receptor due to its ability to recognize all EV-A71 strains. In addition, PSGL-1 is the second EV-A71 receptor discovered. Unlike hSCARB-2, PSGL-1 binding is strain-specific; only 20% of EV-A71 strains isolated to date are able to recognize and bind it. Some other receptors, such as sialylated glycan, Anx 2, HS, HSP90, vimentin, nucleolin and fibronectin, were discovered successively and considered as "co-receptors" because, without hSCARB-2 or PSGL-1, they are not able to mediate entry. For cypA, prohibitin and hWARS, whether they belong to the category of receptors or of co-receptors still needs further investigation. In fact, they have shown to exhibit an hSCARB-2-independent entry. All this information has gradually enriched our knowledge of EV-A71's early stages of infection. In addition to the availability of receptors/co-receptors for EV-A71 on host cells, the complex interaction between the virus and host proteins and various intracellular signaling pathways that are intricately connected to each other is critical for a successful EV-A71 invasion and for escaping the attack of the immune system. However, a lot remains unknown about the EV-A71 entry process. Nevertheless, researchers have been continuously interested in developing EV-A71 entry inhibitors, as this study area offers a large number of targets. To date, important progress has been made toward the development of several inhibitors targeting: receptors/co-receptors, including their soluble forms and chemically designed compounds; virus capsids, such as capsid inhibitors designed on the VP1 capsid; compounds potentially interfering with related signaling pathways, such as MAPK-, IFN- and ATR-inhibitors; and other strategies, such as siRNA and monoclonal antibodies targeting entry. The present review summarizes these latest studies, which are undoubtedly of great significance in developing a novel therapeutic approach against EV-A71.

TBK1 and IRF3 are potential therapeutic targets in Enterovirus A71-associated diseases

BACKGROUND

Enterovirus A71 (EV-A71) is an important causative agent of hand-foot-and-mouth disease (HFMD) associated with enormous healthcare and socioeconomic burden. Although a range of studies about EV-A71 pathogenesis have been well described, the underlying molecular mechanism in terms of innate immune response is still not fully understood, especially the roles of TANK-binding kinase 1 (TBK1) and interferon-regulatory factor 3 (IRF3).

METHODOLOGY/PRINCIPAL FINDINGS

Here, we applied TBK1 inhibitor and IRF3 agonist, for the first time, to evaluate the antiviral activities of TBK1 and IRF3 in vivo. We found that, through regulating EV-A71-induced type I interferon (IFN) response, IRF3 agonist effectively alleviated EV-A71-induced illness, while TBK1 inhibitor aggravated disease progression. In addition, EV-A71 replication was suppressed in EVA-71-infected mice administrated with IRF3 agonist. On the other hand, more severe pathological alterations of neuronal degeneration, muscle fiber breaks, fractured or fused alveolar walls, and diffuse congestion occurred in EVA-71-infected mice treated with TBK1 inhibitor administration. Furthermore, we determined the concentrations of interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), IL-1β, monocyte chemotactic protein-1 (MCP-1), and IL-10 in both lungs and brains of mice and found that TBK1 inhibitor promoted EV-A71-induced inflammatory response, while IRF3 agonist alleviated it, which was consistent with clinical manifestations and pathological alterations.

CONCLUSIONS

Collectively, our findings suggest that TBK1 and IRF3 are potential therapeutic targets in EV-A71-induced illness.

Roles of Non-Coding RNAs in Virus-Host Interaction About Pathogenesis of Hand-Foot-Mouth Disease

Noncoding RNAs (ncRNAs) represent the largest and main transcriptome products and play various roles in the biological activity of cells and pathological processes. Accumulating evidence shows that microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA) are important ncRNAs that play vital regulatory roles during viral infection. Hand-foot-mouth disease (HFMD) virus causes hand-foot-mouth disease, and is also associated with various serious complications and high mortality. However, there is currently no effective treatment. In this review, we focus on advances in the understanding of the modulatory role of ncRNAs during HFMD virus infection. Specifically, we discuss the generation, classification, and regulatory mechanisms of miRNA, lncRNA, and circRNA in the interaction between virus and host, with a particular focus on their influence with viral replication and infection. Analysis of these underlying mechanisms can help provide a foundation for the development of ncRNA-based antiviral therapies.

Role of Non-Coding RNA in Neurological Complications Associated With Enterovirus 71

Enterovirus 71 (EV71) is the main pathogenic virus that causes hand, foot, and mouth disease (HFMD). Studies have reported that EV71-induced infections including aseptic meningitis, acute flaccid paralysis, and even neurogenic pulmonary edema, can progress to severe neurological complications in infants, young children, and the immunosuppressed population. However, the mechanisms through which EV71 causes neurological diseases have not been fully explored. Non-coding RNAs (ncRNAs), are RNAs that do not code for proteins, play a key role in biological processes and disease development associated with EV71. In this review, we summarized recent advances concerning the impacts of ncRNAs on neurological diseases caused by interaction between EV71 and host, revealing the potential role of ncRNAs in pathogenesis, diagnosis and treatment of EV71-induced neurological complications.

IKKε isoform switching governs the immune response against EV71 infection

The reciprocal interactions between pathogens and hosts are complicated and profound. A comprehensive understanding of these interactions is essential for developing effective therapies against infectious diseases. Interferon responses induced upon virus infection are critical for establishing host antiviral innate immunity. Here, we provide a molecular mechanism wherein isoform switching of the host IKKε gene, an interferon-associated molecule, leads to alterations in IFN production during EV71 infection. We found that IKKε isoform 2 (IKKε v2) is upregulated while IKKε v1 is downregulated in EV71 infection. IKKε v2 interacts with IRF7 and promotes IRF7 activation through phosphorylation and translocation of IRF7 in the presence of ubiquitin, by which the expression of IFNβ and ISGs is elicited and virus propagation is attenuated. We also identified that IKKε v2 is activated via K63-linked ubiquitination. Our results suggest that host cells induce IKKε isoform switching and result in IFN production against EV71 infection. This finding highlights a gene regulatory mechanism in pathogen-host interactions and provides a potential strategy for establishing host first-line defense against pathogens.

Essential Role of Non-Coding RNAs in Enterovirus Infection: From Basic Mechanisms to Clinical Prospects

Enteroviruses (EVs) are common RNA viruses that can cause various types of human diseases and conditions such as hand, foot, and mouth disease (HFMD), myocarditis, meningitis, sepsis, and respiratory disorders. Although EV infections in most patients are generally mild and self-limiting, a small number of young children can develop serious complications such as encephalitis, acute flaccid paralysis, myocarditis, and cardiorespiratory failure, resulting in fatalities. Established evidence has suggested that certain non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs) are involved in the occurrence and progression of many human diseases. Recently, the involvement of ncRNAs in the course of EV infection has been reported. Herein, the authors focus on recent advances in the understanding of ncRNAs in EV infection from basic viral pathogenesis to clinical prospects, providing a reference basis and new ideas for disease prevention and research directions.

MicroRNA Signatures Associated with Bronchopulmonary Dysplasia Severity in Tracheal Aspirates of Preterm Infants

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease that develops in neonates as a consequence of preterm birth, arrested fetal lung development, and inflammation. The incidence of BPD remains on the rise as a result of increasing survival of extremely preterm infants. Severe BPD contributes to significant health care costs and is associated with prolonged hospitalizations, respiratory infections, and neurodevelopmental deficits. In this study, we aimed to detect novel biomarkers of BPD severity. We collected tracheal aspirates (TAs) from preterm babies with mild/moderate (n = 8) and severe (n = 17) BPD, and we profiled the expression of 1048 miRNAs using a PCR array. Associations with biological pathways were determined with the Ingenuity Pathway Analysis (IPA) software. We found 31 miRNAs differentially expressed between the two disease groups (2-fold change, false discovery rate (FDR) < 0.05). Of these, 4 miRNAs displayed significantly higher expression levels, and 27 miRNAs had significantly lower expression levels in the severe BPD group when compared to the mild/moderate BPD group. IPA identified cell signaling and inflammation pathways associated with miRNA signatures. We conclude that TAs of extremely premature infants contain miRNA signatures associated with severe BPD. These may serve as potential biomarkers of disease severity in infants with BPD.