Preventing occludin tight-junction disruption via inhibition of microRNA-193b-5p attenuates viral load and influenza-induced lung injury

Intermittent hypoxia-reoxygenation-induced miRNAs inhibit expression of IRF and interferon genes but activate NF-κB and expression of pulmonary fibrosis markers in human small airway epithelial cells

AIM

Intermittent hypoxia-reoxygenation (H/R) has been demonstrated to be associated with aviation and various respiratory diseases, and hence it is of interest to unravel the regulatory mechanisms underlying the H/R-induced innate immune and inflammatory responses in both healthy and COPD-diseased human small airway epithelial cells (SAECs).

MAIN METHODS

The normal healthy and COPD-diseased SAECs (i.e., N-SAECs and D-SAECs) were purchased from PromoCell biotechnology company and respectively cultured under normoxia (21 % O2) or 12/12-h cycles of H/R (i.e., 1 % O2 and 21 % O2 alternately) for 6 days in total for 2D cultures and 21 days in total for the air-liquid interface 3D cultures, followed by qPCR analyses, miRNA fluorescence in situ hybridization, luciferase reporter assays, and immunofluorescence staining.

KEY FINDINGS

Human SAECs cultured under 12/12-h cycles of H/R showed dramatically increased expression of HIF1A and the H/R-inducible miRNAs miR-129-1-3p, miR-1290 and miR-193b-5p, with miR-129-1-3p and miR-193b-5p targeting and inhibiting IRF5 and IRF7 mRNAs, hence downregulating both the type I and II interferon genes in SAECs cultured under H/R. In addition, miR-129-1-3p, miR-1290 and miR-193b-5p all targeted and inhibited SOCS3 mRNA, hence upregulating transactivation of NF-κB and in turn inducing expression of the inflammatory chemokine genes and pulmonary fibrosis-associated marker genes.

SIGNIFICANCE

We show for the first time that intermittent H/R upregulates the NF-κB-induced proinflammatory and fibrosis marker genes whereas downregulates the IRF5/7-induced type I/II interferon expression in human SAECs through distinct HIF1A-inducible miRNAs miR-129-1-3p, miR-193b-5p and miR-1290, which may serve as promising therapeutic targets for airway inflammation and pulmonary fibrosis.

Positive Regulation of Cellular Proteins by Influenza Virus for Productive Infection

Influenza viruses cause annual epidemics and occasional pandemics through respiratory tract infections, giving rise to substantial morbidity and mortality worldwide. Influenza viruses extensively interact with host cellular proteins and exploit a variety of cellular pathways to accomplish their infection cycle. Some of the cellular proteins that display negative effects on the virus are degraded by the virus. However, there are also various proteins upregulated by influenza at the expression and/or activation levels. It has been well-established that a large number of host antiviral proteins such as type I interferon-stimulated genes are elevated by viral infection. On the other hand, there are also many cellular proteins that are induced directly by the virus, which are considered as pro-viral factors and often indispensable for rigorous viral propagation or pathogenicity. Here, we review the recent advances in our understanding of the cellular factors deemed to be upregulated and utilized by the influenza virus. The focus is placed on the functions of these pro-viral proteins and the mechanisms associated with promoting viral amplification, evading host immunity, or enhancing viral pathogenicity. Investigating the process of how influenza viruses hijack cellular proteins could provide a framework for inventing the host-factor-targeted drugs to conquer influenza.

Hepatocyte-Enriched miRNA-193b-3p Promotes Hepatitis B Virus Replication by Dual Activation of Viral Core Promoter Activity and Autophagy Induction by Targeting IGF-1R

Hepatitis B virus (HBV) infection is a principal cause of severe liver disease in humans and is associated with increased levels of specific serum or intracellular microRNAs (miRNAs). Among these, miR-193b-3p is a liver-enriched miRNA; however, its role in HBV replication remains unknown. This study aimed to investigate the influence of chronic HBV infection on miR-193b-3p levels in the peripheral blood and liver tissues of patients with chronic hepatitis B (CHB), evaluate the effect of miR-193b-3p on HBV replication both in vitro and in vivo, and elucidate the potential underlying mechanisms. We showed that hepatic miR-193b-3p levels in patients with CHB were significantly elevated compared with those in healthy controls. Ectopic expression of miR-193b-3p significantly enhanced HBV replication and transcription in different hepatoma cell lines. Furthermore, we identified IGF-1R as a direct target through which miR-193b-3p regulates HBV replication. Mechanistically, miR-193b-3p increased HBV core promoter activity via the IGF-1R/FXRα axis, thereby enhancing HBV transcription. Additionally, miR-193b-3p increased IGF-1R/Akt/MDM2/p53 signaling-mediated autophagy induction, which in turn facilitated increased HBV post-transcriptional activity. Collectively, hepatocyte-enriched miR-193b-3p exerts a proviral effect on HBV replication through dual synergistic mechanisms, offering novel insights into its role in HBV replication and potential therapeutic implications in CHB infection.

INTESTINAL EPITHELIAL-SPECIFIC OCCLUDIN DELETION WORSENS GUT PERMEABILITY AND SURVIVAL FOLLOWING SEPSIS

ABSTRACT

Sepsis induces intestinal hyperpermeability, which is associated with higher mortality. Occludin is a tight junction protein that plays a critical role in regulating disease-associated intestinal barrier loss. This study examined the role of intestinal occludin on gut barrier function and survival in a preclinical model of sepsis. Intestinal epithelial-specific occludin knockout (occludin KO IEC ) mice and wild type controls were subjected to intra-abdominal sepsis and sacrificed at predetermined endpoints for mechanistic studies or followed for survival. Occludin KO IEC mice had a significant increase in intestinal permeability, which was induced only in the setting of sepsis as knockout mice and control mice had similar baseline permeability. The worsened barrier was specific to the leak pathway of permeability, without changes in either the pore or unrestricted pathways. Increased sepsis-induced permeability was associated with increased levels of the tight junction ZO-1 in occludin KO IEC mice. Occludin KO IEC mice also had significant increases in systemic cytokines IL-6 and MCP-1 and increased bacteremia. Furthermore, occludin KO IEC mice had higher levels of jejunal IL-1β and MCP-1 as well as increased MCP-1 and IL-17A in the peritoneal fluid although peritoneal bacteria levels were unchanged. Notably, 7-day mortality was significantly higher in occludin KO IEC mice following sepsis. Occludin thus plays a critical role in preserving gut barrier function and mediating survival during sepsis, associated with alterations in inflammation and bacteremia. Agents that preserve occludin function may represent a new therapeutic strategy in the treatment of sepsis.

Influenza virus-induced type I interferons disrupt alveolar epithelial repair and tight junction integrity in the developing lung

Recently, we demonstrated that influenza A virus (IAV)-infected murine neonates lacking a functional IFN-I receptor (IFNAR-/-) had significantly improved survival and reduced lung pathology relative to wild-type (WT) neonates. In direct contrast, adult IFNAR-/- mice display enhanced morbidity following IAV infection relative to WT adults. We hypothesized that IAV-induced IFN-I signaling in primary neonatal type II alveolar epithelial cells (TIIECs), the main cell type of IAV infection and initiator of host response in the lung, contributed to age-specific viral pathogenesis. Multifactorial transcriptional analysis of purified TIIECs revealed age, not infection status, as the primary driver of transcriptional differences in TIIECs. Subsequent pathway analysis demonstrated IAV-infected IFNAR-/- neonates significantly upregulated cell proliferation, tissue repair and tight junction genes at 2-days post-infection (dpi), compared to WT neonates. Next, to determine if these growth and repair differences persisted later in infection, targeted analysis of repair gene expression and immunofluorescent quantification of pulmonary sealing tight junction molecules ZO-1 and occludin was performed at 6-dpi. Relative to WT neonates, IFNAR-/- neonates had significantly higher whole lung occludin staining and repair gene expression. Together, our data demonstrates IFN-I signaling is extremely pathogenic in the developing lung by disrupting alveolar repair and pulmonary barrier integrity.

Umbilical Cord Mesenchymal Stem Cells Could Reduce Lung Damage Caused by H1N1 Influenza Virus Infection

Influenza A virus infection can cause acute respiratory distress syndrome (ARDS), and to date, viral pneumonia has been the main cause of ARDS. Bone marrow mesenchymal stem cells have shown promise for treating lung injury caused by avian influenza virus infection. At present, studies of the use of other stem cell types to treat human influenza virus-mediated lung damage are sparse. We assessed the use of umbilical cord mesenchymal stem cells (UC-MSCs) to treat damage from serious H1N1 influenza virus infections in cell and animal-based experiments. Maximum viral titers, inflammatory factor expression levels, differential expression of alveolar cell-related proteins, animal weight and survival rate, lung histopathology, and other indicators were evaluated. Compared with the control group, in cellular experiments, UC-MSCs could effectively inhibit H1N1 influenza viral replication and repair damaged host cells. In animal experiments, UC-MSCs reduced expression of pro-inflammatory cytokines, reduced entry of inflammatory cells into the lungs, alleviated lung inflammation, significantly reduced the extent of lung injury in mice, and improved lung histopathology, improving overall survival. A positive role of umbilical cord-derived mesenchymal stem cells in treating lung injury caused by H1N1 influenza virus infection that is worthy of clinical promotion has been demonstrated.

Transcriptional analysis reveals the suppression of RAD51 and disruption of the homologous recombination pathway during PEDV infection in IPEC-J2 cells

PEDV is a highly contagious enteric pathogen that can cause severe diarrhea and death in neonatal pigs. Despite extensive research, the molecular mechanisms of host's response to PEDV infection remain unclear. In this study, differentially expressed genes (DEGs), time-specific coexpression modules, and key regulatory genes associated with PEDV infection were identified. The analysis revealed 2,275, 1,492, and 3,409 DEGs in infected vs. mock-treated pigs at 12 h, 24 h, and 48 h, respectively. Time series analysis revealed that the upregulated genes were involved mainly in antiviral pathways such as the viral defense response and the regulation of immune system processes. Protein-protein interaction network analysis identified the top 20 core genes in the interaction network, which included six upregulated genes (TFRC, SUOX, RMI1, CD74, IFIH1, and CD86) and 14 downregulated genes (FOS, CDC6, CDCA3, PIK3R2, TUFM, VARS, ASF1B, POLD1, MCM8, POLA1, CDC45, BCS1L, RAD51, and RPA2). In addition, GSEA enrichment analysis revealed that pathways such as DNA replication and homologous recombination involving RAD51, CDC6, and RPA2 were significantly inhibited during viral infection. Our findings not only reveal dynamic changes in the transcriptome profile of PEDV-infected IPEC-J2 cells but also provide novel insights into the mechanism of PEDV infection of the host.

The Molecular Basis of Asthma Exacerbations Triggered by Viral Infections: The Role of Specific miRNAs

Viral respiratory infections are a significant clinical problem among the pediatric population and are one of the leading causes of hospitalization. Most often, upper respiratory tract infections are self-limiting. Still, those that involve the lower respiratory tract are usually associated with asthma exacerbations, leading to worsening or even the initiation of the disease. A key role in regulating the immune response and inflammation during viral infections and their impact on the progression of asthma has been demonstrated for miRNA molecules (microRNA). Their interaction with mRNA (messenger RNA) regulates gene expression in innate and acquired immune responses, making them valuable biomarkers for diagnostics, monitoring, and predicting asthma exacerbations. The following paper presents changes in the expression of miRNAs during the five most common viral infections causing asthma worsening, with particular emphasis on the pediatric population. In addition, we describe the molecular mechanisms by which miRNAs influence the pathogenesis of viral infection, immune responses, and asthma exacerbations. These molecules represent promising targets for future innovative therapeutic strategies, paving the way for developing personalized medicine for patients with viral-induced asthma exacerbations.

Lactobacillus salivarius ameliorates Mycoplasma gallisepticum-induced inflammation via the JAK/STAT signaling pathway involving respiratory microbiota and metabolites

Mycoplasma gallisepticum (MG) can cause chronic respiratory disease (CRD) in chickens, which has a significant negative economic impact on the global poultry sector. Respiratory flora is the guardian of respiratory health, and its disorder is closely related to respiratory immunity and respiratory diseases. As a common probiotic in the chicken respiratory tract, Lactobacillus salivarius (L. salivarius) has potential antioxidant, growth performance enhancing, and anti-immunosuppressive properties. However, the specific mechanism through which L. salivarius protects against MG infection has not yet been thoroughly examined. This study intends to investigate whether L. salivarius could reduce MG-induced tracheal inflammation by modulating the respiratory microbiota and metabolites. The results indicated that L. salivarius reduced MG colonization significantly and alleviated the anomalous morphological changes by using the MG-infection model. L. salivarius also reduced the level of Th1 cell cytokines, increased the level of Th2 cell cytokines, and ameliorated immune imbalance during MG infection. In addition, L. salivarius improved the mucosal barrier, heightened immune function, and suppressed the Janus kinase/Signal transducer, and activator of transcription (JAK/STAT) signaling pathway. Notably, MG infection changed the composition of the respiratory microbiota and metabolites, and L. salivarius therapy partially reversed the aberrant respiratory microbiota and metabolite composition. Our results highlighted that these findings demonstrated that L. salivarius played a role in MG-mediated inflammatory damage and demonstrated that L. salivarius, by altering the respiratory microbiota and metabolites, could successfully prevent MG-induced inflammatory injury in chicken trachea.

Rujin Jiedu decoction protects against influenza virus infection by modulating gut microbiota

Background

Rujin Jiedu decoction (RJJDD) is a classical prescription of Traditional Chinese Medicine that has long been applied to treat pneumonia caused by external infection, but whether and how it benefits influenza virus therapy remains largely unclear. The aim of this study was to investigate the anti-inflammatory effect of RJJDD on the mouse model of influenza and to explore its potential mechanism.

Methods

The mice were mock-infected with PBS or infected with PR8 virus followed by treatment with RJJDD or antiviral oseltamivir. The weight loss and morbidity of mice were monitored daily. Network pharmacology is used to explore the potential pathways that RJJDD may modulate. qRT-PCR and ELISA were performed to assess the expression of inflammatory cytokines in the lung tissue and macrophages. The intestinal feces were collected for 16S rDNA sequencing to assess the changes in gut microbiota.

Results

We demonstrate that RJJDD protects against IAV-induced pneumonia. Comprehensive network pharmacology analyses of the Mass Spec-identified components of RJJDD suggest that RJJDD may act through down-regulating key signaling pathways producing inflammatory cytokines, which was experimentally confirmed by cytokine expression analysis in IAV-infected mouse lung tissues and IAV single-strand RNA mimic R837-induced macrophages. Furthermore, gut microbiota analysis indicates that RJJDD prevented IAV-induced dysbiosis of host intestinal flora, thereby offering a mechanistic explanation for RJJDD's efficacy in influenza pneumonia.

Conclusion

This study defines a previously uncharacterized role for RJJDD in protecting against influenza likely by maintaining homeostasis of gut microbiota, and provides a new therapeutic option for severe influenza.

Tiny Guides, Big Impact: Focus on the Opportunities and Challenges of miR-Based Treatments for ARDS

Acute Respiratory Distress Syndrome (ARDS) is characterized by lung inflammation and increased membrane permeability, which represents the leading cause of mortality in ICUs. Mechanical ventilation strategies are at the forefront of supportive approaches for ARDS. Recently, an increasing understanding of RNA biology, function, and regulation, as well as the success of RNA vaccines, has spurred enthusiasm for the emergence of novel RNA-based therapeutics. The most common types of RNA seen in development are silencing (si)RNAs, antisense oligonucleotide therapy (ASO), and messenger (m)RNAs that collectively account for 80% of the RNA therapeutics pipeline. These three RNA platforms are the most mature, with approved products and demonstrated commercial success. Most recently, miRNAs have emerged as pivotal regulators of gene expression. Their dysregulation in various clinical conditions offers insights into ARDS pathogenesis and offers the innovative possibility of using microRNAs as targeted therapy. This review synthesizes the current state of the literature to contextualize the therapeutic potential of miRNA modulation. It considers the potential for miR-based therapeutics as a nuanced approach that incorporates the complexity of ARDS pathophysiology and the multifaceted nature of miRNA interactions.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.