Matrix Metalloproteinase 9 Exerts Antiviral Activity against Respiratory Syncytial Virus

Azithromycin therapy in infants hospitalized for respiratory syncytial virus bronchiolitis: Airway matrix metalloproteinase-9 levels and subsequent recurrent wheeze

BACKGROUND

Early life respiratory syncytial virus (RSV) bronchiolitis is a significant risk factor for childhood asthma. In vitro and in vivo studies suggested that decreasing levels of airway matrix metalloproteinase (MMP)-9 during RSV bronchiolitis may be associated with clinical benefits.

OBJECTIVE

To investigate whether azithromycin therapy during severe RSV bronchiolitis reduces upper airway MMP-9 levels, whether upper airway MMP-9 levels correlate with upper airway interleukin IL-8 levels, and whether MMP-9 level reduction is associated with reduced post-RSV recurrent wheeze (RW).

METHODS

A total of 200 otherwise healthy 1- to 18-month-old infants hospitalized with RSV bronchiolitis were randomized into a double-blind, placebo-controlled trial of oral azithromycin (10 mg/kg daily for 7 days followed by 5 mg/kg daily for 7 days) or placebo. Infants were followed for 2 to 4 years for the outcome of RW (3 or more wheezing episodes). Nasal lavage samples for MMP-9 levels were obtained at baseline, day 14 (end of the study treatment), and after 6 months.

RESULTS

Upper airway MMP-9 levels were highly correlated with IL-8 levels at all 3 time points: randomization, day 14, and 6 months (r = 0.80; P < .0001 for all time points). MMP-9 levels were similar between treatment groups at randomization, were lower on day 14 among children treated with azithromycin (P = .0085), but no longer different after 6 months. MMP-9 levels at baseline and change from baseline to day 14 were not associated with the development of RW (P = .49, .39, respectively).

CONCLUSION

Azithromycin therapy in children hospitalized with RSV bronchiolitis had a short-term anti-inflammatory effect in reducing upper airway MMP-9 levels. However, the reduction in MMP-9 levels did not relate to subsequent RW post-RSV.

TRIAL REGISTRATION

This study is a secondary analysis of the Azithromycin to Prevent Wheezing following severe RSV bronchiolitis-II clinical trial registered at Clinicaltrials.gov (NCT02911935).

Pediatric human nose organoids demonstrate greater susceptibility, epithelial responses, and cytotoxicity than adults during RSV infection

Respiratory syncytial virus (RSV) is a common cause of respiratory infections, causing significant morbidity and mortality, especially in young children. Why RSV infection in children is more severe as compared to healthy adults is not fully understood. In the present study, we infect both pediatric and adult human nose organoid-air liquid interface (HNO-ALIs) cell lines with two contemporary RSV isolates and demonstrate how they differ in virus replication, induction of the epithelial cytokine response, cell injury, and remodeling. Pediatric HNO-ALIs were more susceptible to early RSV replication, elicited a greater overall cytokine response, demonstrated enhanced mucous production, and manifested greater cellular damage compared to their adult counterparts. Adult HNO-ALIs displayed enhanced mucus production and robust cytokine response that was well controlled by superior regulatory cytokine response and possibly resulted in lower cellular damage than in pediatric lines. Taken together, our data suggest substantial differences in how pediatric and adult upper respiratory tract epithelium responds to RSV infection. These differences in epithelial cellular response can lead to poor mucociliary clearance and predispose infants to a worse respiratory outcome of RSV infection.

Auraptene Has Antiviral Activity against Human Coronavirus OC43 in MRC-5 Cells

Auraptene (7-geranyloxycoumarin) is the abundant prenyloxycoumarin found in the fruits of Citrus spp. Auraptene has a variety of pharmacological and therapeutic functions, such as anticancer, antioxidant, immunomodulatory, and anti-inflammation activities, with excellent safety profiles. In this study, we evaluated the anticoronaviral activity of auraptene in HCoV-OC43-infected human lung fibroblast MRC-5 cells. We found that auraptene effectively inhibited HCoV-OC43-induced cytopathic effects with 4.3 μM IC₅₀ and 6.1 μM IC₉₀, resulting in a selectivity index (CC₅₀/IC₅₀) of >3.5. Auraptene treatment also decreased viral RNA levels in HCoV-OC43-infected cells, as detected through quantitative real-time PCR, and decreased the expression level of spike proteins and nucleocapsid proteins in virus-infected cells, as detected through the Western blot analysis and immunofluorescence staining. Time-of-addition analysis showed auraptene's inhibitory effects at the post-entry stage of the virus life cycle; however, auraptene did not induce the antiviral interferon families, IFN-α1, IFN-β1, and IFN-λ1. Additionally, auraptene-treated MRC-5 cells during HCoV-OC43 infection decreased the MMP-9 mRNA levels which are usually increased due to the infection, as auraptene is a previously reported MMP-9 inhibitor. Therefore, auraptene showed antiviral activity against HCoV-OC43 infection, and we suggest that auraptene has the potential to serve as a therapeutic agent against human coronavirus.

Exploring the role of neutrophils in infectious and noninfectious pulmonary disorders

With the change in global environment, respiratory disorders are becoming more threatening to the health of people all over the world. These diseases are closely linked to performance of immune system. Within the innate arm of immune system, Neutrophils are an important moiety to serve as an immune defense barrier. They are one of the first cells recruited to the site of infection and plays a critical role in pathogenesis of various pulmonary diseases. It is established that the migration and activation of neutrophils can lead to inflammation either directly or indirectly and this inflammation caused is very crucial for the clearance of pathogens and resolution of infection. However, the immunopathological mechanisms involved to carry out the same is very complex and not well understood. Despite there being studies concentrating on the role of neutrophils in multiple respiratory diseases, there is still a long way to go in order to completely understand the complexity of the participation of neutrophils and mechanisms involved in the development of these respiratory diseases. In the present article, we have reviewed the literature to comprehensively provide an insight in the current development and advancements about the role of neutrophils in infectious respiratory disorders including viral respiratory disorders such as Coronavirus disease (COVID-19) and bacterial pulmonary disorders with a focused review on pulmonary tuberculosis as well as in noninfectious disorders like Chronic obstructive pulmonary disease (COPD) and asthma. Also, future directions into research and therapeutic targets have been discussed for further exploration.

Low protease activity in B cell follicles promotes retention of intact antigens after immunization

The structural integrity of vaccine antigens is critical to the generation of protective antibody responses, but the impact of protease activity on vaccination in vivo is poorly understood. We characterized protease activity in lymph nodes and found that antigens were rapidly degraded in the subcapsular sinus, paracortex, and interfollicular regions, whereas low protease activity and antigen degradation rates were detected in the vicinity of follicular dendritic cells (FDCs). Correlated with these findings, immunization regimens designed to target antigen to FDCs led to germinal centers dominantly targeting intact antigen, whereas traditional immunizations led to much weaker responses that equally targeted the intact immunogen and antigen breakdown products. Thus, spatially compartmentalized antigen proteolysis affects humoral immunity and can be exploited.

Targeted proteomics identifies circulating biomarkers associated with active COVID-19 and post-COVID-19

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic is caused by the highly infectious Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). There is an urgent need for biomarkers that will help in better stratification of patients and contribute to personalized treatments. We performed targeted proteomics using the Olink platform and systematically investigated protein concentrations in 350 hospitalized COVID-19 patients, 186 post-COVID-19 individuals, and 61 healthy individuals from 3 independent cohorts. Results revealed a signature of acute SARS-CoV-2 infection, which is represented by inflammatory biomarkers, chemokines and complement-related factors. Furthermore, the circulating proteome is still significantly affected in post-COVID-19 samples several weeks after infection. Post-COVID-19 individuals are characterized by upregulation of mediators of the tumor necrosis (TNF)-α signaling pathways and proteins related to transforming growth factor (TGF)-ß. In addition, the circulating proteome is able to differentiate between patients with different COVID-19 disease severities, and is associated with the time after infection. These results provide important insights into changes induced by SARS-CoV-2 infection at the proteomic level by integrating several cohorts to obtain a large disease spectrum, including variation in disease severity and time after infection. These findings could guide the development of host-directed therapy in COVID-19.

Quercetin attenuates viral infections by interacting with target proteins and linked genes in chemicobiological models

Medicinally active compounds in the flavonoid class of phytochemicals are being studied for antiviral action against various DNA and RNA viruses. Quercetin is a flavonoid present in a wide range of foods, including fruits and vegetables. It is said to be efficient against a wide range of viruses. This research investigated the usefulness of Quercetin against Hepatitis C virus, Dengue type 2 virus, Ebola virus, and Influenza A using computational models. A molecular docking study using the online tool PockDrug was accomplished to identify the best binding sites between Quercetin and PubChem-based receptors. Network-pharmacological assay to opt to verify function-specific gene-compound interactions using STITCH, STRING, GSEA, Cytoscape plugin cytoHubba. Quercetin explored tremendous binding affinity against NS5A protein for HCV with a docking score of - 6.268 kcal/mol, NS5 for DENV-2 with a docking score of - 5.393 kcal/mol, VP35 protein for EBOV with a docking score of - 4.524 kcal/mol, and NP protein for IAV with a docking score of - 6.954 kcal/mol. In the network-pharmacology study, out of 39 hub genes, 38 genes have been found to interact with Quercetin and the top interconnected nodes in the protein-protein network were (based on the degree of interaction with other nodes) AKT1, EGFR, SRC, MMP9, MMP2, KDR, IGF1R, PTK2, ABCG2, and MET. Negative binding energies were noticed in Quercetin-receptor interaction. Results demonstrate that Quercetin could be a potential antiviral agent against these viral diseases with further study in in-vivo models.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-022-00132-2.

Neutrophil subsets and their differential roles in viral respiratory diseases

Neutrophils play significant roles in immune homeostasis and as neutralizers of microbial infections. Recent evidence further suggests heterogeneity of neutrophil developmental and activation states that exert specialized effector functions during inflammatory disease conditions. Neutrophils can play multiple roles during viral infections, secreting inflammatory mediators and cytokines that contribute significantly to host defense and pathogenicity. However, their roles in viral immunity are not well understood. In this review, we present an overview of neutrophil heterogeneity and its impact on the course and severity of viral respiratory infectious diseases. We focus on the evidence demonstrating the crucial roles neutrophils play in the immune response toward respiratory infections, using influenza as a model. We further extend the understanding of neutrophil function with the studies pertaining to COVID‐19 disease and its neutrophil‐associated pathologies. Finally, we discuss the relevance of these results for future therapeutic options through targeting and regulating neutrophil‐specific responses.

Molecular Mechanism of Jinchan Oral Liquid in the Treatment of Children with Respiratory Syncytial Virus Pneumonia Based on Network Pharmacology and Molecular Docking Technology

Objective

Exploration of the underlying molecular mechanism of Jinchan Oral Liquid (JOL) in treating children with the respiratory syncytial virus (RSV) pneumonia to provide new evidence for the clinical application.

Methods

The active components and target genes of JOL were screened by the TCMSP database. The targets of RSV pneumonia were obtained from the GeneCards, OMIM, DrugBank, and PharmGKB database. Then, we constructed the active component-target network and screened the core genes. The overlaps were screened for PPI network analysis, GO analysis, and KEGG analysis. Finally, result validation was performed by molecular docking.

Results

According to the screening criteria of the ADME, 74 active compounds of JOL were obtained; after removing redundant targets, we selected 180 potential targets. By screening the online database, 893 RSV pneumonia-related targets were obtained. A total of 82 overlapping genes were chosen by looking for the intersection. The STRING online database was used to acquire PPI relationships, and 16 core genes were obtained. GO and KEGG analyses showed that the main pathways of JOL in treating RSV pneumonia include TNF signaling pathway and IL17 signaling pathway. The molecular docking results showed that the active compounds of JOL had a good affinity with the core genes.

Conclusion

In this study, we preliminarily discussed the main active ingredients, related targets, and pathways of JOL and predicted the pharmacodynamic basis and the potential therapeutic mechanisms of RSV pneumonia. In summary, the network pharmacology strategy may be helpful for the discovery of multitarget drugs against complex diseases.

The human nose organoid respiratory virus model: an ex-vivo human challenge model to study RSV and SARS-CoV-2 pathogenesis and evaluate therapeutics

There is an unmet need for pre-clinical models to understand the pathogenesis of human respiratory viruses; and predict responsiveness to immunotherapies. Airway organoids can serve as an ex-vivo human airway model to study respiratory viral pathogenesis; however, they rely on invasive techniques to obtain patient samples. Here, we report a non-invasive technique to generate human nose organoids (HNOs) as an alternate to biopsy derived organoids. We made air liquid interface (ALI) cultures from HNOs and assessed infection with two major human respiratory viruses, respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Infected HNO-ALI cultures recapitulate aspects of RSV and SARS-CoV-2 infection, including viral shedding, ciliary damage, innate immune responses, and mucus hyper-secretion. Next, we evaluated the feasibility of the HNO-ALI respiratory virus model system to test the efficacy of palivizumab to prevent RSV infection. Palivizumab was administered in the basolateral compartment (circulation) while viral infection occurred in the apical ciliated cells (airways), simulating the events in infants. In our model, palivizumab effectively prevented RSV infection in a concentration dependent manner. Thus, the HNO-ALI model can serve as an alternate to lung organoids to study respiratory viruses and testing therapeutics.

Neutrophils in respiratory viral infections

Viral respiratory infections are a common cause of severe disease, especially in infants, people who are immunocompromised, and in the elderly. Neutrophils, an important innate immune cell, infiltrate the lungs rapidly after an inflammatory insult. The most well-characterized effector mechanisms by which neutrophils contribute to host defense are largely extracellular and the involvement of neutrophils in protection from numerous bacterial and fungal infections is well established. However, the role of neutrophils in responses to viruses, which replicate intracellularly, has been less studied. It remains unclear whether and, by which underlying immunological mechanisms, neutrophils contribute to viral control or confer protection against an intracellular pathogen. Furthermore, neutrophils need to be tightly regulated to avoid bystander damage to host tissues. This is especially relevant in the lung where damage to delicate alveolar structures can compromise gas exchange with life-threatening consequences. It is inherently less clear how neutrophils can contribute to host immunity to viruses without causing immunopathology and/or exacerbating disease severity. In this review, we summarize and discuss the current understanding of how neutrophils in the lung direct immune responses to viruses, control viral replication and spread, and cause pathology during respiratory viral infections.

The Human Nose Organoid Respiratory Virus Model: an Ex Vivo Human Challenge Model To Study Respiratory Syncytial Virus (RSV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Pathogenesis and Evaluate Therapeutics

There is an unmet need for preclinical models to understand the pathogenesis of human respiratory viruses and predict responsiveness to immunotherapies. Airway organoids can serve as an ex vivo human airway model to study respiratory viral pathogenesis; however, they rely on invasive techniques to obtain patient samples. Here, we report a noninvasive technique to generate human nose organoids (HNOs) as an alternative to biopsy-derived organoids. We made air-liquid interface (ALI) cultures from HNOs and assessed infection with two major human respiratory viruses, respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Infected HNO-ALI cultures recapitulate aspects of RSV and SARS-CoV-2 infection, including viral shedding, ciliary damage, innate immune responses, and mucus hypersecretion. Next, we evaluated the feasibility of the HNO-ALI respiratory virus model system to test the efficacy of palivizumab to prevent RSV infection. Palivizumab was administered in the basolateral compartment (circulation), while viral infection occurred in the apical ciliated cells (airways), simulating the events in infants. In our model, palivizumab effectively prevented RSV infection in a concentration-dependent manner. Thus, the HNO-ALI model can serve as an alternative to lung organoids to study respiratory viruses and test therapeutics. IMPORTANCE Preclinical models that recapitulate aspects of human airway disease are essential for the advancement of novel therapeutics and vaccines. Here, we report a versatile airway organoid model, the human nose organoid (HNO), that recapitulates the complex interactions between the host and virus. HNOs are obtained using noninvasive procedures and show divergent responses to SARS-CoV-2 and RSV infection. SARS-CoV-2 induces severe damage to cilia and the epithelium, no interferon-λ response, and minimal mucus secretion. In striking contrast, RSV induces hypersecretion of mucus and a profound interferon-λ response with ciliary damage. We also demonstrated the usefulness of our ex vivo HNO model of RSV infection to test the efficacy of palivizumab, an FDA-approved monoclonal antibody to prevent severe RSV disease in high-risk infants. Our study reports a breakthrough in both the development of a novel nose organoid model and in our understanding of the host cellular response to RSV and SARS-CoV-2 infection.

Leveraging 3D Model Systems to Understand Viral Interactions with the Respiratory Mucosa

Respiratory viruses remain a significant cause of morbidity and mortality in the human population, underscoring the importance of ongoing basic research into virus-host interactions. However, many critical aspects of infection are difficult, if not impossible, to probe using standard cell lines, 2D culture formats, or even animal models. In vitro systems such as airway epithelial cultures at air-liquid interface, organoids, or 'on-chip' technologies allow interrogation in human cells and recapitulate emergent properties of the airway epithelium-the primary target for respiratory virus infection. While some of these models have been used for over thirty years, ongoing advancements in both culture techniques and analytical tools continue to provide new opportunities to investigate airway epithelial biology and viral infection phenotypes in both normal and diseased host backgrounds. Here we review these models and their application to studying respiratory viruses. Furthermore, given the ability of these systems to recapitulate the extracellular microenvironment, we evaluate their potential to serve as a platform for studies specifically addressing viral interactions at the mucosal surface and detail techniques that can be employed to expand our understanding.

Matrix metalloproteinase inhibitors identified from Camellia sinensis for COVID-19 prophylaxis: an in silico approach

To respond to the public panic, government and private research organizations of every country keep working on the COVID-19 pandemic, even though still there is a lack of more efficacious medicine for the choice of Coronavirus disease treatment. To counteract on this situation several approved drugs including anti-malarial (hydroxychloroquine and chloroquine), and few anti-viral (remdesvir) agents are choice of treatment for COVID-19. However, these agents suffer from certain limitation in their uses and pointed that there is no specific treatment or vaccine available to counter this contagious disease. Hence, there is urgent requirement to find a specific cure for the disease. In this view, there are several ongoing clinical trials of both western and traditional medicines. In present study, phytochemicals from Camellia sinensis were retrieved from the database and identified based on their ability to inhibit matrix metalloproteinase (MMPs) against SARS-CoV-2 main protease. Camellia sinensis entails of a massive number of phytochemicals with a good source of polyphenols such as Catechin, Epicatechin, Epigallocatechin and (–)-Epigallocatechin gallate. Molecular docking was performed using the GLIDE docking module of Schrodinger Suite software. The analysis displayed docking score for the five polyphenols i.e. theaflavin (− 8.701), 1-O-caffeoylquinic acid (− 7.795), Genistein (− 7.168), Epigallocatechin 3-gallate (− 6.282) and Ethyl trans-caffeate (− 5.356). Interestingly, theaflavin and Epigallocatechin 3-gallate have not revealed any side effects. These polyphenolic compounds had a strong binding affinity with hydrogen bonds and a good drug-likeness score. Therefore, Camellia sinensis could be the beneficial option in the prophylaxis of the COVID-19 outbreak.

Integration of transcriptomic profile of SARS-CoV-2 infected normal human bronchial epithelial cells with metabolic and protein-protein interaction networks

A novel coronavirus (SARS-CoV-2, formerly known as nCoV-2019) that causes an acute respiratory disease has emerged in Wuhan, China and spread globally in early 2020. On January the 30th, the World Health Organization (WHO) declared spread of this virus as an epidemic and a public health emergency. With its highly contagious characteristic and long incubation time, confinement of SARS-CoV-2 requires drastic lock-down measures to be taken and therefore early diagnosis is crucial. We analysed transcriptome of SARS-CoV-2 infected human lung epithelial cells, compared it with mock-infected cells, used network-based reporter metabolite approach and integrated the transcriptome data with protein-protein interaction network to elucidate the early cellular response. Significantly affected metabolites have the potential to be used in diagnostics while pathways of protein clusters have the potential to be used as targets for supportive or novel therapeutic approaches. Our results are in accordance with the literature on response of IL6 family of cytokines and their importance, in addition, we find that matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) with keratan sulfate synthesis pathway may play a key role in the infection. We hypothesize that MMP9 inhibitors have potential to prevent "cytokine storm" in severely affected patients.

Expression pattern and association analysis of porcine matrix metallopeptidase 9 (MMP9) with diarrhea and performance traits in piglets

Matrix metalloproteinase 9 (MMP9) plays critical roles in multiple biological processes, such as reproduction, cell proliferation and differentiation, and host defenses. The aim of this study was to evaluate whether MMP9 is a candidate gene for resistance to diarrhea in piglets. In this study, quantitative real-time PCR was used to analyze the expression of MMP9 mRNA in different tissues of specific pathogen-free piglets. MMP9 was expressed in all the tissues (heart, liver, spleen, lung, kidney, stomach, duodenum, jejunum, ileum, and colon) analyzed. An association analysis between MMP9 polymorphisms and piglet diarrhea score and performance traits were performed in Min (Chinese indigenous breed) and Landrace populations. In the statistical analysis, at the g.48178429 G>A locus, AA piglets had a lower diarrhea score than that of GA in the Min population (P < .05), whereas GG had higher day-35 body weight and average daily gain (ADG) than AA in the Landrace breed (P < .05). At the rs336583561 locus, Min piglets with the GG genotype have a lower diarrhea score than AG piglets (P < .05). At g.48184777C>T, CC animals have higher body weight than TC Landrace piglets (P < .05 or P < .01). A 5' flanking deletion assay indicated that g.48178429 G>A was not located in the MMP9 promoter region. Our results suggest that the A allele at the g.48178429 G>A locus and the G allele at rs336583561 are resistance alleles in Min pigs. Before these markers are used in pig breeding programs, more studies in larger populations are needed.

Interferon response to respiratory syncytial virus by bronchial epithelium from children with asthma is inversely correlated with pulmonary function

BACKGROUND

Respiratory viral infection in early childhood, including that from respiratory syncytial virus (RSV), has been previously associated with the development of asthma.

OBJECTIVE

We aimed to determine whether ex vivo RSV infection of bronchial epithelial cells (BECs) from children with asthma would induce specific gene expression patterns and whether such patterns were associated with lung function among BEC donors.

METHODS

Primary BECs from carefully characterized children with asthma (n = 18) and matched healthy children without asthma (n = 8) were differentiated at an air-liquid interface for 21 days. Air-liquid interface cultures were infected with RSV for 96 hours and RNA was subsequently isolated from BECs. In each case, we analyzed gene expression using RNA sequencing and assessed differences between conditions by linear modeling of the data. BEC donors completed spirometry to measure lung function.

RESULTS

RSV infection of BECs from subjects with asthma, compared with uninfected BECs from subjects with asthma, led to a significant increase in expression of 6199 genes. There was significantly greater expression of 195 genes in BECs from children with asthma and airway obstruction (FEV₁/forced vital capacity < 0.85 and FEV₁ < 100% predicted) than in BECs from children with asthma without obstruction, or in BECs from healthy children. These specific genes were found to be highly enriched for viral response genes induced in parallel with types I and III interferons.

CONCLUSIONS

BECs from children with asthma and with obstructive physiology exhibit greater expression of types I and III interferons and interferon-stimulated genes than do cells from children with normal lung function, and expression of interferon-associated genes correlates with the degree of airway obstruction. These findings suggest that an exaggerated interferon response to viral infection by airway epithelial cells may be a mechanism leading to lung function decline in a subset of children with asthma.

Neutralization of matrix metalloproteinase-9 potentially enhances oncolytic efficacy of tanapox virus for melanoma therapy

Matrix metalloproteinases (MMPs), which are involved in degradation of extracellular matrix, are critical regulators in tumor progression, metastasis and angiogenesis. Although induction of MMPs is frequently observed during the viral infection, the effect of MMPs on viral replication varies between viruses. MMP-9, for instance, is upregulated and promotes the replication of some viruses, such as herpes simplex virus, but inhibits the replication of others. Here, we report that infection with tanapox virus (TPV) promotes the expression of MMP-9 in the melanoma cells. In addition, we show that MMP-9 exerts an anti-viral effect on TPV replication and plays a protective role in TPV-infected melanoma cells in vitro. Moreover, the neutralization of MMP-9 in melanoma cells remarkably enhances the TPV infection and leads to a significant reduction in cell survival. In summary, this study contributes to understanding of the role played by MMP-9 in TPV infectivity and provides more insights for using TPV as cancer virotherapy in future studies. Since TPV has shown substantial oncolytic efficacy in promoting melanoma tumor regression in animal models, identifying mechanisms that suppress MMP-9 expression upon TPV infection can potentially improve its use as a melanoma virotherapy.

Matrix Metalloproteinase 9 Facilitates Hepatitis B Virus Replication through Binding with Type I Interferon (IFN) Receptor 1 To Repress IFN/JAK/STAT Signaling

Hepatitis B virus (HBV) infection may cause acute hepatitis B, chronic hepatitis B (CHB), liver cirrhosis, and hepatocellular carcinoma (HCC). However, the mechanisms by which HBV evades host immunity and maintains chronic infection are largely unknown. Here, we revealed that matrix metalloproteinase 9 (MMP-9) is activated in peripheral blood mononuclear cells (PBMCs) of HBV-infected patients, and HBV stimulates MMP-9 expression in macrophages and PBMCs isolated from healthy individuals. MMP-9 plays important roles in the breakdown of the extracellular matrix and in the facilitation of tumor progression, invasion, metastasis, and angiogenesis. MMP-9 also regulates respiratory syncytial virus (RSV) replication, but the mechanism underlying such regulation is unknown. We further demonstrated that MMP-9 facilitates HBV replication by repressing the interferon (IFN)/Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, IFN action, STAT1/2 phosphorylation, and IFN-stimulated gene (ISG) expression. Moreover, MMP-9 binds to type I IFN receptor 1 (IFNAR1) and facilitates IFNAR1 phosphorylation, ubiquitination, subcellular distribution, and degradation to interfere with the binding of IFANR1 to IFN-α. Thus, we identified a novel positive-feedback regulation loop between HBV replication and MMP-9 production. On one hand, HBV activates MMP-9 in infected patients and leukocytes. On the other hand, MMP-9 facilitates HBV replication through repressing IFN/JAK/STAT signaling, IFNAR1 function, and IFN-α action. Therefore, HBV may take the advantage of MMP-9 function to establish or maintain chronic infection.IMPORTANCE Hepatitis B virus (HBV) infection may cause chronic hepatitis B (CHB) and hepatocellular carcinoma (HCC). However, the mechanisms by which HBV maintains chronic infection are largely unknown. Matrix metalloproteinase 9 (MMP-9) plays important roles in the facilitation of tumor progression, invasion, metastasis, and angiogenesis. However, the effects of MMP-9 on HBV replication and pathogenesis are not known. This study reveals that MMP-9 expression is activated in patients with CHB, and HBV stimulates MMP-9 production in PBMCs and macrophages. More interestingly, MMP-9 in turn promotes HBV replication through suppressing IFN-α action. Moreover, MMP-9 interacts with type I interferon receptor 1 (IFNAR1) to disturb the binding of IFN-α to IFNAR1 and facilitate the phosphorylation, ubiquitination, subcellular distribution, and degradation of IFNAR1. Therefore, these results discover a novel role of MMP-9 in viral replication and reveal a new mechanism by which HBV evades host immunity to maintain persistent infection.

HIV infection model of chronic obstructive pulmonary disease in mice

Cigarette smoke usage is prevalent in human immunodeficiency virus (HIV)-positive patients, and, despite highly active antiretroviral therapy, these individuals develop an accelerated form of chronic obstructive pulmonary disease (COPD). Studies investigating the mechanisms of COPD development in HIV have been limited by the lack of suitable mouse models. Here we describe a model of HIV-induced COPD in wild-type mice using EcoHIV, a chimeric HIV capable of establishing chronic infection in immunocompetent mice. A/J mice were infected with EcoHIV and subjected to whole body cigarette smoke exposure. EcoHIV was detected in alveolar macrophages of mice. Compared with uninfected mice, concomitant EcoHIV infection significantly reduced forced expiratory flow 50%/forced vital capacity and enhanced distal airspace enlargement following cigarette smoke exposure. Lung IL-6, granulocyte-macrophage colony-stimulating factor, neutrophil elastase, cathepsin G, and matrix metalloproteinase-9 expression was significantly enhanced in smoke-exposed EcoHIV-infected mice. These changes coincided with enhanced IκBα, ERK1/2, p38, and STAT3 phosphorylation and lung cell apoptosis. Thus, the EcoHIV smoke exposure mouse model reproduces several of the pathophysiological features of HIV-related COPD in humans, indicating that this murine model can be used to determine key parameters of HIV-related COPD and to test future therapies for this disorder.

TLR9 expression is required for the development of cigarette smoke-induced emphysema in mice

The expression of Toll-like receptor (TLR)-9, a pathogen recognition receptor that recognizes unmethylated CpG sequences in microbial DNA molecules, is linked to the pathogenesis of several lung diseases. TLR9 expression and signaling was investigated in animal and cell models of chronic obstructive pulmonary disease (COPD). We observed enhanced TLR9 expression in mouse lungs following exposure to cigarette smoke. Tlr9(-/-) mice were resistant to cigarette smoke-induced loss of lung function as determined by mean linear intercept, total lung capacity, lung compliance, and tissue elastance analysis. Tlr9 expression also regulated smoke-mediated immune cell recruitment to the lung; apoptosis; expression of granulocyte-colony stimulating factor (G-CSF), the CXCL5 protein, and matrix metalloproteinase-2 (MMP-2); and protein tyrosine phosphatase 1B (PTP1B) activity in the lung. PTP1B, a phosphatase with anti-inflammatory abilities, was identified as binding to TLR9. In vivo delivery of a TLR9 agonist enhanced TLR9 binding to PTP1B, which inactivated PTP1B. Ptp1b(-/-) mice had elevated lung concentrations of G-CSF, CXCL5, and MMP-2, and tissue expression of type-1 interferon following TLR9 agonist administration, compared with wild-type mice. TLR9 responses were further determined in fully differentiated normal human bronchial epithelial (NHBE) cells isolated from nonsmoker, smoker, and COPD donors, and then cultured at air liquid interface. NHBE cells from smokers and patients with COPD expressed more TLR9 and secreted greater levels of G-CSF, IL-6, CXCL5, IL-1β, and MMP-2 upon TLR9 ligand stimulation compared with cells from nonsmoker donors. Although TLR9 combats infection, our results indicate that TLR9 induction can affect lung function by inactivating PTP1B and upregulating expression of proinflammatory cytokines.

Understanding respiratory syncytial virus (RSV) vaccine development and aspects of disease pathogenesis

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract infections causing bronchiolitis and some mortality in young children and the elderly. Despite decades of research there is no licensed RSV vaccine. Although significant advances have been made in understanding the immune factors responsible for inducing vaccine-enhanced disease in animal models, less information is available for humans. In this review, we discuss the different types of RSV vaccines and their target population, the need for establishing immune correlates for vaccine efficacy, and how the use of different animal models can help predict vaccine efficacy and clinical outcomes in humans.