Autophagy, TGF-β, and SMAD-2/3 Signaling Regulates Interferon-β Response in Respiratory Syncytial Virus Infected Macrophages

The relationship between autophagy and respiratory viruses

Respiratory viruses have caused severe global health problems and posed essential challenges to the medical community. In recent years, the role of autophagy as a critical process in cells in viral respiratory diseases has been noticed. One of the vital catabolic biological processes in the body is autophagy. Autophagy contributes to energy recovery by targeting and selectively directing foreign microorganisms, organelles, and senescent intracellular proteins to the lysosome for degradation and phagocytosis. Activation or suppression of autophagy is often initiated when foreign pathogenic organisms such as viruses infect cells. Because of its antiviral properties, several viruses may escape or resist this process by encoding viral proteins. Viruses can also use autophagy to enhance their replication or prolong the persistence of latent infections. Here, we provide an overview of autophagy and respiratory viruses such as coronavirus, rhinovirus, parainfluenza, influenza, adenovirus, and respiratory syncytial virus, and examine the interactions between them and the role of autophagy in the virus-host interaction process and the resulting virus replication strategy.

The Role of the NRF2 Pathway in the Pathogenesis of Viral Respiratory Infections

In humans, acute and chronic respiratory infections caused by viruses are associated with considerable morbidity and mortality. Respiratory viruses infect airway epithelial cells and induce oxidative stress, yet the exact pathogenesis remains unclear. Oxidative stress activates the transcription factor NRF2, which plays a key role in alleviating redox-induced cellular injury. The transcriptional activation of NRF2 has been reported to affect both viral replication and associated inflammation pathways. There is complex bidirectional crosstalk between virus replication and the NRF2 pathway because virus replication directly or indirectly regulates NRF2 expression, and NRF2 activation can reversely hamper viral replication and viral spread across cells and tissues. In this review, we discuss the complex role of the NRF2 pathway in the regulation of the pathogenesis of the main respiratory viruses, including coronaviruses, influenza viruses, respiratory syncytial virus (RSV), and rhinoviruses. We also summarize the scientific evidence regarding the effects of the known NRF2 agonists that can be utilized to alter the NRF2 pathway.

Feeding with 4,4'-diaponeurosporene-producing Bacillus subtilis enhances the lactogenic immunity of sow

Specific antibodies produced sow by oral porcine epidemic diarrhea virus (PEDV) vaccines would transfer to newborn piglets via colostrum, and it is an effective strategy to prevent porcine epidemic diarrhea (PED). However, there is a lag in the development of corresponding vaccines due to the rapid mutation of PEDV, which could increase the difficulty of PED prevention and control in pig farms. Hence, congenital lactogenic immunity was assessed by feeding 4,4'-diaponeurosporene-producing Bacillus subtilis (B.S-Dia) to sow on the 80th day of gestation in order to protect newborn piglets from PEDV infection. Firstly, we found that the quantities of T lymphocytes and monocytes in the blood and colostrum after oral administration of B.S-Dia were significantly increased as observed by flow cytometry, whereas the proliferative activity of T lymphocytes in colostrum was also markedly increased. Furthermore, enzyme-linked immunosorbent assay (ELISA) results revealed that levels of TGF (Transforming growth factor) -β, Interleukin (IL) -6, lysozyme and lactoferrin were significantly increased. Finally, it was found in the piglets' challenge protection test that offspring pigs of the sows feeding B.S-Dia during pregnancy did not develop diarrhea symptoms and intestinal pathological changes at 48 h after infection with PEDV, and PEDV load in the jejunum and ileum was significantly reduced, but offspring pigs of the sows taking orally PBS during pregnancy developed pronounced diarrhea symptoms and extensive PEDV colonization was noted both in the jejunum and ileum. In summary, sow by oral administration of B.S-Dia substantially increased congenital lactogenic immunity, thereby preventing newborn piglets from being infected with PEDV.

The matrix protein of respiratory syncytial virus suppresses interferon signaling via RACK1 association

IMPORTANCE

Respiratory syncytial virus (RSV) matrix (M) protein is indispensable for virion assembly and release. It is localized to the nucleus during early infection to perturb host transcription. However, the function of RSV M protein in other cellular activities remains poorly understood. In this study, several interferon response-associated host factors, including RACK1, were identified by proteomic analysis as RSV M interactors. Knockdown of RACK1 attenuates RSV-restricted IFN signaling leading to enhanced host defense against RSV infection, unraveling a role of M protein in antagonizing IFN response via association with RACK1. Our study uncovers a previously unrecognized mechanism of immune evasion by RSV M protein and identifies RACK1 as a novel host factor recruited by RSV, highlighting RACK1 as a potential new target for RSV therapeutics development.

Genome-wide association study identifies several loci for HEV seropositivity

Hepatitis E viral (HEV) infection imposes a heavy global health burden. The variability in the prevalence of serological markers of HEV infection between different ethnic groups proposes a host genetic influence. Here, we report genetic polymorphisms associated with anti-HEV antibody positivity and level using binary- and quantitative-trait genome-wide association studies (GWAS) on a population from Qatar (n = 5829). We identified a region in 12p11.1 (lead SNP: rs559856097, allele: A, p = 2.3 × 10-10) significantly associated with anti-HEV antibodies level. This intergenic variant is located near SNORD112, a small nucleolar RNA (snoRNA). Additional gene-set and pathway enrichment analyses highlighted a strong correlation with anti-viral response-related pathways, including IFNs (alpha/beta) and interleukin-21 (IL-21) signaling. This is the first GWAS on the response to HEV infection. Further replication and functional experimentation are warranted to validate these findings.

Knockdown of the Autophagy Protein Beclin-1 Does Not Affect Innate Cytokine Production in Human Lung Epithelial Cells during Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in young children, globally. Autophagy is a cellular degradation process that mediates cell survival. Studies using mouse models have demonstrated that inhibiting autophagy affects the production of cytokines triggered by RSV. However, the effect of autophagy on RSV-induced cytokine production in human cells remains inadequately studied. Our previous research showed that inhibiting autophagy using pharmacological inhibitors did not affect the innate cytokine production in human lung epithelial cells (BEAS-2B) following RSV infection. In this study, we sought to validate these findings using a more specific approach, employing short-interfering RNA (siRNA) to target the important autophagy protein Beclin-1 (Bec-1). Prior to measuring cytokine production, we confirmed that silencing Bec-1 with siRNA effectively suppressed autophagy without affecting cell viability. Our results revealed that inhibiting autophagy through Bec-1 knockdown did not affect the production of innate cytokines CXCL8 and CCL5 in BEAS-2B cells during RSV infection, consistent with our previous findings using pharmacological inhibitors. Overall, our data suggest that targeting autophagy may not be an effective strategy for alleviating RSV-induced airway inflammation.

WDR74 facilitates TGF-β/Smad pathway activation to promote M2 macrophage polarization and diabetic foot ulcer wound healing in mice

Diabetic foot ulcer (DFU) is a devastating component of diabetes progression, leading to decreased quality of life and increased mortality in diabetic patients. The underlying mechanism of DFU is not completely understood. Hence, this study aims to elucidate the mechanism involved in wound healing in mouse models of DFU. Gain- and loss-of-function studies were performed to study the roles that WDR74 and TGF-β play in mouse models of DFU and primary bone marrow-derived mouse macrophages. M1 and M2 macrophage phenotypic markers, extracellular matrix (ECM) components, and angiogenic makers were determined by RT-qPCR and/or Western blot analysis. Localization of these proteins was determined by immunofluorescence staining and/or immunohistochemistry. Interaction between WDR74 with Smad2/3 in macrophages was detected by co-immunoprecipitation. We found that WDR74 and M2 macrophages were decreased in wound tissues from DFU mice. TGF-β/Smad pathway activation increased the expression of M2 macrophage markers (arginase-1 and YM1), IL-4, while decreased expression of M1 macrophage marker (iNOS). TGF-β/Smad pathway activation also increased the production of ECM and promoted the wound closure in diabetic mice. We also noticed that WDR74 overexpression increased Smad2/3 phosphorylation, elevated the population of M2 macrophage and ECM production, and alleviated DFU. LY2109761 treatment normalized effects of TGF-β or WDR74 overexpression. In conclusion, WDR74 promoted M2 macrophage polarization, leading to improved DFU in mice, through activation of the TGF-β/Smad pathway. Graphical Headlights 1. WDR74 promotes M2 macrophage polarization and ECM production. 2. WDR74 activates the TGF-β/Smad signaling pathway. 3. TGF-β/Smad activation promotes M2 macrophage polarization in murine DFU. 4. WDR74 enhances wound healing in murine DFU.

A Water-Soluble Hydrogen Sulfide Donor Suppresses the Growth of Hepatocellular Carcinoma via Inhibiting the AKT/GSK-3β/β-Catenin and TGF-β/Smad2/3 Signaling Pathways

Hepatocellular carcinoma (HCC) is a disease with high morbidity, high mortality, and low cure rate. Hyaluronic acid (HA) is widely adopted in tissue engineering and drug delivery. 5-(4-Hydroxyphenyl)-3H-1, 2-dithiol-3-thione (ADT-OH) is one of commonly used H₂S donors. In our previous study, HA-ADT was designed and synthesized via coupling of HA and ADT-OH. In this study, compared with sodium hydrosulfide (NaHS, a fast H₂S-releasing donor) and morpholin-4-ium (4-methoxyphenyl)-morpholin-4-ylsulfanylidenesulfido-λ5-phosphane (GYY4137, a slow H₂S-releasing donor), HA-ADT showed stronger inhibitory effect on the proliferation, migration, invasion, and cell cycle of human HCC cells. HA-ADT promoted apoptosis by suppressing the expressions of phospho (p)-protein kinase B (PKB/AKT), p-glycogen synthase kinase-3β (GSK-3β), p-β-catenin, and also inhibited autophagy via the downregulation of the protein levels of p-Smad2, p-Smad3, and transforming growth factor-β (TGF-β) in human HCC cells. Moreover, HA-ADT inhibited HCC xenograft tumor growth more effectively than both NaHS and GYY4137. Therefore, HA-ADT can suppress the growth of HCC cells by blocking the AKT/GSK-3β/β-catenin and TGF-β/Smad2/3 signaling pathways. HA-ADT and its derivatives may be developed as promising antitumor drugs.

Transforming growth factor-β in tumour development

Transforming growth factor-β (TGFβ) is a ubiquitous cytokine essential for embryonic development and postnatal tissue homeostasis. TGFβ signalling regulates several biological processes including cell growth, proliferation, apoptosis, immune function, and tissue repair following injury. Aberrant TGFβ signalling has been implicated in tumour progression and metastasis. Tumour cells, in conjunction with their microenvironment, may augment tumourigenesis using TGFβ to induce epithelial-mesenchymal transition, angiogenesis, lymphangiogenesis, immune suppression, and autophagy. Therapies that target TGFβ synthesis, TGFβ-TGFβ receptor complexes or TGFβ receptor kinase activity have proven successful in tissue culture and in animal models, yet, due to limited understanding of TGFβ biology, the outcomes of clinical trials are poor. Here, we review TGFβ signalling pathways, the biology of TGFβ during tumourigenesis, and how protein quality control pathways contribute to the tumour-promoting outcomes of TGFβ signalling.

N-Linked Glycans Shape Skin Immune Responses during Arthritis and Myositis after Intradermal Infection with Ross River Virus

Arthritogenic alphaviruses are mosquito-borne arboviruses that include several re-emerging human pathogens, including the chikungunya (CHIKV), Ross River (RRV), Mayaro (MAYV), and o'nyong-nyong (ONNV) virus. Arboviruses are transmitted via a mosquito bite to the skin. Herein, we describe intradermal RRV infection in a mouse model that replicates the arthritis and myositis seen in humans with Ross River virus disease (RRVD). We show that skin infection with RRV results in the recruitment of inflammatory monocytes and neutrophils, which together with dendritic cells migrate to draining lymph nodes (LN) of the skin. Neutrophils and monocytes are productively infected and traffic virus from the skin to LN. We show that viral envelope N-linked glycosylation is a key determinant of skin immune responses and disease severity. RRV grown in mammalian cells elicited robust early antiviral responses in the skin, while RRV grown in mosquito cells stimulated poorer early antiviral responses. We used glycan mass spectrometry to characterize the glycan profile of mosquito and mammalian cell-derived RRV, showing deglycosylation of the RRV E2 glycoprotein is associated with curtailed skin immune responses and reduced disease following intradermal infection. Altogether, our findings demonstrate skin infection with an arthritogenic alphavirus leads to musculoskeletal disease and envelope glycoprotein glycosylation shapes disease outcome. IMPORTANCE Arthritogenic alphaviruses are transmitted via mosquito bites through the skin, potentially causing debilitating diseases. Our understanding of how viral infection starts in the skin and how virus systemically disseminates to cause disease remains limited. Intradermal arbovirus infection described herein results in musculoskeletal pathology, which is dependent on viral envelope N-linked glycosylation. As such, intradermal infection route provides new insights into how arboviruses cause disease and could be extended to future investigations of skin immune responses following infection with other re-emerging arboviruses.

The Multifaceted Roles of Autophagy in Infectious, Obstructive, and Malignant Airway Diseases

Autophagy is a highly conserved dynamic process by which cells deliver their contents to lysosomes for degradation, thus ensuring cell homeostasis. In response to environmental stress, the induction of autophagy is crucial for cell survival. The dysregulation of this degradative process has been implicated in a wide range of pathologies, including lung diseases, representing a relevant potential target with significant clinical outcomes. During lung disease progression and infections, autophagy may exert both protective and harmful effects on cells. In this review, we will explore the implications of autophagy and its selective forms in several lung infections, such as SARS-CoV-2, Respiratory Syncytial Virus (RSV) and Mycobacterium tuberculosis (Mtb) infections, and different lung diseases such as Cystic Fibrosis (CF), Chronic Obstructive Pulmonary Disease (COPD), and Malignant Mesothelioma (MM).

Regulation of IRF3 activation in Human Antiviral Signalling Pathways

The interferon regulatory factor (IRF) family of transcription factors play a vital role in the human innate antiviral immune responses with production of interferons (IFNs) as a hallmark outcome of activation. In recent years, IRF3 has been considered a principal early regulator of type I IFNs (TI-IFNs) directly downstream of intracellular virus sensing. Despite decades of research on IRF-activating pathways, many questions remain on the regulation of IRF3 activation. The kinases IκB kinase epsilon (IKKε) and TANK-binding kinase-1 (TBK1) and the scaffold proteins TRAF family member-associated NF-kappa-B activator (TANK), NF-kappa-B-activating kinase-associated protein 1 (NAP1) and TANK-binding kinase 1-binding protein 1 (TBKBP1)/similar to NAP1 TBK1 adaptor (SINTBAD) are believed to be core components of an IRF3-activation complex yet their contextual involvement and complex composition are still unclear. This review will give an overview of antiviral signaling pathways leading to the activation of IRF3 and discuss recent developments in our understanding of its proximal regulation.

Human Respiratory Syncytial Virus NS2 Protein Induces Autophagy by Modulating Beclin1 Protein Stabilization and ISGylation

Paramyxoviruses such as respiratory syncytial virus (RSV) are the leading cause of pneumonia in infants, the elderly, and immunocompromised individuals. Understanding host-virus interactions is essential for the development of effective interventions. RSV induces autophagy to modulate the immune response. The viral factors and mechanisms underlying RSV-induced autophagy are unknown. Here, we identify the RSV nonstructural protein NS2 as the virus component mediating RSV-induced autophagy. We show that NS2 interacts and stabilizes the proautophagy mediator Beclin1 by preventing its degradation by the proteasome. NS2 further impairs interferon-stimulated gene 15 (ISG15)-mediated Beclin1 ISGylation and generates a pool of "hypo-ISGylated" active Beclin1 to engage in functional autophagy. Studies with NS2-deficient RSV revealed that NS2 contributes to RSV-mediated autophagy during infection. The present study is the first report to show direct activation of autophagy by a paramyxovirus nonstructural protein. We also report a new viral mechanism for autophagy induction wherein the viral protein NS2 promotes hypo-ISGylation of Beclin1 to ensure availability of active Beclin1 to engage in the autophagy process. IMPORTANCE Understanding host-virus interactions is essential for the development of effective interventions against respiratory syncytial virus (RSV), a paramyxovirus that is a leading cause of viral pneumonia in infants. RSV induces autophagy following infection, although the viral factors involved in this mechanism are unknown. Here, we identify the RSV nonstructural protein 2 (NS2) as the virus component involved in autophagy induction. NS2 promotes autophagy by interaction with and stabilization of the proautophagy mediator Beclin1 and by impairing its ISGylation to overcome autophagy inhibition. To the best of our knowledge, this is the first report of a viral protein regulating the autophagy pathway by modulating ISGylation of autophagy mediators. Our studies highlight a direct role of a paramyxovirus nonstructural protein in activating autophagy by interacting with the autophagy mediator Beclin1. NS2-mediated regulation of the autophagy and ISGylation processes is a novel function of viral nonstructural proteins to control the host response against RSV.

Agnuside mitigates OVA-LPS induced perturbed lung homeostasis via modulating inflammatory, autophagy, apoptosis-fibrosis response and myeloid lineages in mice model of allergic asthma

Attributes of agnuside, a nontoxic, iridoid glycoside have been advocated for inflammatory disorders. However, information on its efficacy in alleviating allergic asthma largely remain ambiguous and yet to be deciphered. Present study aimed to assess efficacy of agnuside in targeting vicious circle of oxi-inflammation, autophagy and fibrosis, together with investigating its underlying molecular mechanism during OVA-LPS induced allergic asthma. Results revealed that agnuside showed prophylactic effect in assuaging asthmatic lung architecture impairment (p ≤ 0.01) as indicated by suppression of inflammatory cell infiltration, congestion, fibrosis, airway remodeling and alveolar collapse in OVA-LPS sensitized group. Decreased expression level (p ≤ 0.05) of allergic inflammatory mediators such as IgE, Th1/Th2, IL-4/IFN-γ, IL-4/IL-10, chemokines, endopeptidases and TGF-β, Smad2/4, Caspase9/3, connexin 43/50 observed in agnuside treatments. Analysis of redox molecular signaling cascade and autophagic proteins revealed concurrent upregulation in p-NF-κB, p-PI3K, p-Akt, p-p38, p-Stat3 activation, GATA3, LC3B expression and reduction in Bcl2/Bax, Beclin1 and p62 expression in sensitized mice (p ≤ 0.05) which were intensely counteracted by administration of agnuside. Suppression in myeloid cells activation and augmentation (p ≤ 0.001) of Tregs established modulatory attribute of agnuside for innate and adaptive immune response during allergic asthma. Collectively, these outcomes confer prophylactic attribute of agnuside and signify it as promising strategy to thwart allergic asthma.

Comparative Investigation of Gene Regulatory Processes Underlying Avian Influenza Viruses in Chicken and Duck

Simple Summary

Avian influenza poses a great risk to gallinaceous poultry, while mallard ducks can withstand most virus strains. To date, the mechanisms underlying the susceptibility of chicken and the effective immune response of duck have not been completely understood. In this study, our aim is to investigate the transcriptional gene regulation governing the expression of important avian-influenza-induced genes and to reveal the master regulators stimulating an effective immune response after virus infection in ducks while dysfunctioning in chicken.

Abstract

The avian influenza virus (AIV) mainly affects birds and not only causes animals’ deaths, but also poses a great risk of zoonotically infecting humans. While ducks and wild waterfowl are seen as a natural reservoir for AIVs and can withstand most virus strains, chicken mostly succumb to infection with high pathogenic avian influenza (HPAI). To date, the mechanisms underlying the susceptibility of chicken and the effective immune response of duck have not been completely unraveled. In this study, we investigate the transcriptional gene regulation underlying disease progression in chicken and duck after AIV infection. For this purpose, we use a publicly available RNA-sequencing dataset from chicken and ducks infected with low-pathogenic avian influenza (LPAI) H5N2 and HPAI H5N1 (lung and ileum tissues, 1 and 3 days post-infection). Unlike previous studies, we performed a promoter analysis based on orthologous genes to detect important transcription factors (TFs) and their cooperation, based on which we apply a systems biology approach to identify common and species-specific master regulators. We found master regulators such as EGR1, FOS, and SP1, specifically for chicken and ETS1 and SMAD3/4, specifically for duck, which could be responsible for the duck’s effective and the chicken’s ineffective immune response.

The complexity of biological control systems: An autophagy case study

Autophagy and YAP1-WWTR1/TAZ signalling are tightly linked in a complex control system of forward and feedback pathways which determine different cellular outcomes in differing cell types at different time-points after perturbations. Here we extend our previous experimental and modelling approaches to consider two possibilities. First, we have performed additional mathematical modelling to explore how the autophagy-YAP1 crosstalk may be controlled by posttranslational modifications of components of the pathways. Second, since analogous contrasting results have also been reported for autophagy as a regulator of other transduction pathways engaged in tumorigenesis (Wnt/β-catenin, TGF-β/Smads, NF-kB or XIAP/cIAPs), we have considered if such discrepancies may be explicable through situations involving competing pathways and feedback loops in different cell types, analogous to the autophagy-YAP/TAZ situation. Since distinct posttranslational modifications dominate those pathways in distinct cells, these need to be understood to enable appropriate cell type-specific therapeutic strategies for cancers and other diseases.

Peripherally-driven myeloid NFkB and IFN/ISG responses predict malignancy risk, survival, and immunotherapy regime in ovarian cancer

Background

Tumors can influence peripheral immune macroenvironment, thereby creating opportunities for non-invasive serum/plasma immunobiomarkers for immunostratification and immunotherapy designing. However, current approaches for immunobiomarkers’ detection are largely quantitative, which is unreliable for assessing functional peripheral immunodynamics of patients with cancer. Hence, we aimed to design a functional biomarker modality for capturing peripheral immune signaling in patients with cancer for reliable immunostratification.

Methods

We used a data-driven in silico framework, integrating existing tumor/blood bulk-RNAseq or single-cell (sc)RNAseq datasets of patients with cancer, to inform the design of an innovative serum-screening modality, that is, serum-functional immunodynamic status (sFIS) assay. Next, we pursued proof-of-concept analyses via multiparametric serum profiling of patients with ovarian cancer (OV) with sFIS assay combined with Luminex (cytokines/soluble immune checkpoints), CA125-antigen detection, and whole-blood immune cell counts. Here, sFIS assay’s ability to determine survival benefit or malignancy risk was validated in a discovery (n=32) and/or validation (n=699) patient cohorts. Lastly, we used an orthotopic murine metastatic OV model, with anti-OV therapy selection via in silico drug–target screening and murine serum screening via sFIS assay, to assess suitable in vivo immunotherapy options.

Results

In silico data-driven framework predicted that peripheral immunodynamics of patients with cancer might be best captured via analyzing myeloid nuclear factor kappa-light-chain enhancer of activated B cells (NFκB) signaling and interferon-stimulated genes' (ISG) responses. This helped in conceptualization of an ‘in sitro’ (in vitro+in situ) sFIS assay, where human myeloid cells were exposed to patients’ serum in vitro, to assess serum-induced (si)-NFκB or interferon (IFN)/ISG responses (as active signaling reporter activity) within them, thereby ‘mimicking’ patients’ in situ immunodynamic status. Multiparametric serum profiling of patients with OV established that sFIS assay can: decode peripheral immunology (by indicating higher enrichment of si-NFκB over si-IFN/ISG responses), estimate survival trends (si-NFκB or si-IFN/ISG responses associating with negative or positive prognosis, respectively), and coestimate malignancy risk (relative to benign/borderline ovarian lesions). Biologically, we documented dominance of pro-tumorigenic, myeloid si-NFκB response^HIGHsi-IFN/ISG response^LOW inflammation in periphery of patients with OV. Finally, in an orthotopic murine metastatic OV model, sFIS assay predicted the higher capacity of chemo-immunotherapy (paclitaxel–carboplatin plus anti-TNF antibody combination) in achieving a pro-immunogenic peripheral milieu (si-IFN/ISG response^HIGHsi-NFκB response^LOW), which aligned with high antitumor efficacy.

Conclusions

We established sFIS assay as a novel biomarker resource for serum screening in patients with OV to evaluate peripheral immunodynamics, patient survival trends and malignancy risk, and to design preclinical chemo-immunotherapy strategies.

Depletion of TAX1BP1 Amplifies Innate Immune Responses during Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the main cause of acute respiratory infections in young children and also has a major impact on the elderly and immunocompromised people. In the absence of a vaccine or efficient treatment, a better understanding of RSV interactions with the host antiviral response during infection is needed. Previous studies revealed that cytoplasmic inclusion bodies (IBs), where viral replication and transcription occur, could play a major role in the control of innate immunity during infection by recruiting cellular proteins involved in the host antiviral response. We recently showed that the morphogenesis of IBs relies on a liquid-liquid-phase separation mechanism depending on the interaction between viral nucleoprotein (N) and phosphoprotein (P). These scaffold proteins are expected to play a central role in the recruitment of cellular proteins to IBs. Here, we performed a yeast two-hybrid screen using RSV N protein as bait and identified the cellular protein TAX1BP1 as a potential partner of this viral protein. This interaction was validated by pulldown and immunoprecipitation assays. We showed that TAX1BP1 suppression has only a limited impact on RSV infection in cell cultures. However, RSV replication is decreased in TAX1BP1-deficient (TAX1BP1 knockout [TAX1BP1KO]) mice, whereas the production of inflammatory and antiviral cytokines is enhanced. In vitro infection of wild-type or TAX1BP1KO alveolar macrophages confirmed that the innate immune response to RSV infection is enhanced in the absence of TAX1BP1. Altogether, our results suggest that RSV could hijack TAX1BP1 to restrain the host immune response during infection. IMPORTANCE Respiratory syncytial virus (RSV), which is the leading cause of lower respiratory tract illness in infants, remains a medical problem in the absence of a vaccine or efficient treatment. This virus is also recognized as a main pathogen in the elderly and immunocompromised people, and the occurrence of coinfections (with other respiratory viruses and bacteria) amplifies the risks of developing respiratory distress. In this context, a better understanding of the pathogenesis associated with viral respiratory infections, which depends on both viral replication and the host immune response, is needed. The present study reveals that the cellular protein TAX1BP1, which interacts with the RSV nucleoprotein N, participates in the control of the innate immune response during RSV infection, suggesting that the N-TAX1BP1 interaction represents a new target for the development of antivirals.

Inhibition of autophagy promotes human RSV NS1-induced inflammation and apoptosis in vitro

Human respiratory syncytial virus (RSV) is a major health challenge due to the lack of a safe and effective vaccine and antiviral drugs. RSV non-structural protein 1 (NS1) is the main inhibitor of antiviral signaling pathways in RSV infection; however, the underlying mechanism is unclear. The aim of the present study was to investigate of the role of NS1 and its relationship with autophagy. NS1-Flag plasmid was transfected into A549 cells and the levels of inflammatory cytokines, autophagy markers and apoptosis were detected. In addition, the cells were treated with an autophagy inhibitor, 3-methyladenine for 12 h prior to transfection with the NS1 plasmid to explore the role of autophagy in NS1-transfected cells. The results showed that the production of inflammatory cytokines and autophagy was induced in NS1-transfected cells, and indicated that autophagy prevents the production of cytokines and the activation of apoptosis. Furthermore, the results demonstrated that NS1 activated autophagy partly through the mTOR-p70 S6 kinase signaling pathway. The results suggest that autophagy induced by NS1 transfection through the mTOR pathway can hinder the production of inflammatory cytokines and interferon-α and inhibit cell apoptosis, which may help to explain why autophagy has been shown to be beneficial to viral replication in most studies.

Vitex negundo Linn. extract alleviates inflammatory aggravation and lung injury by modulating AMPK/PI3K/Akt/p38-NF-κB and TGF-β/Smad/Bcl2/caspase/LC3 cascade and macrophages activation in murine model of OVA-LPS induced allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

There is growing inclination towards developing bioactive molecule-based strategies for the management of allergic airway inflammation associated respiratory diseases. Vitex negundo Linn., also known as Nirgundi, is one such medicinal plant enriched with phytochemicals and used for inflammatory and respiratory disorders including asthma in traditional system of medicine. Preliminary studies have claimed anti-tussive and bronchodilator potential of V. negundo Linn. However, its attributes as well as molecular mechanism (s) in modulation of asthma mediated by allergic inflammation are yet to be delineated scientifically.

AIM OF THE STUDY

Present study attempted to assess the effectiveness of Vitex negundo leaf extract (VNLE) in mitigation of allergen induced inflammation associated asthmatic lung damage with emphasis to delineate its molecular mechanism (s).

MATERIALS AND METHODS

Allergic lung inflammation was established in Balb/c mice using Ovalbumin-lipopolysaccharide (OVA-LPS). Several allergic inflammatory parameters, histopathological changes, alveolar macrophage activation and signalling pathways were assessed to examine protective effects of VNLE. UHPLC-DAD-QTOF-ESI-IMS was used to characterize VLNE.

RESULTS

VNLE administration effectively attenuated LPS-induced oxi-inflammatory stress in macrophages suggesting its anti-inflammatory potential. Further, VNLE showed protective effect in mitigating asthmatic lung damage as evident by reversal of pathological changes including inflammatory cell influx, congestion, fibrosis, bronchial thickness and alveolar collapse observed in allergen group. VNLE suppressed expressions of inflammatory Th1/Th2 cytokines, chemokines, endopeptidases (MMPs), oxidative effector enzyme (iNOS), adhesion molecules, IL-4/IFN-γ release with simultaneous enhancement in levels of IL-10, IFN-γ, MUC3 and tight junction proteins. Subsequent mechanistic investigation revealed that OVA-LPS concomitantly enhanced phosphorylation of NF-κB, PI3K, Akt and p38MAPKs and downregulated AMPK which was categorically counteracted by VNLE treatment. VNLE also suppressed OVA-LPS induced fibrosis, apoptosis, autophagy and gap junction proteins which were affirmed by reduction in TGF-β, Smad2/3/4, Caspase9/3, Bax, LC3A/B, connexin 50, connexin 43 and enhancement in Bcl2 expression. Additionally, suppression of alveolar macrophage activation, inflammatory cells in blood and elevation of splenic CD8+T cells was demonstrated. UHPLC-DAD-QTOF-ESI-IMS revealed presence of iridoids glycoside and phenolics which might contribute these findings.

CONCLUSION

These findings confer protective effect of VNLE in attenuation of allergic lung inflammation and suggest that it could be considered as valuable medicinal source for developing safe natural therapeutics for mitigation of allergic inflammation during asthma.

Inhibition of Autophagy Does Not Affect Innate Cytokine Production in Human Lung Epithelial Cells During Respiratory Syncytial Virus Infection

Human respiratory syncytial virus (RSV) is one of the major causes of childhood acute lower respiratory tract infection worldwide. Autophagy is an intracellular pathway involved in nutrient recycling. Recently, autophagy has been reported to play a role in regulating host cytokine response to several viruses, including vesicular stomatitis virus and human immunodeficiency virus. Previous in vivo studies using mouse model has shown that inhibition of autophagy reduces RSV-induced cytokine production. However, the role of autophagy in modulating RSV-induced cytokine response in human cells has not been reported. We investigated the role of autophagy in regulating the production of the cytokines C-X-C motif ligand 8 (CXCL8) and C-C motif ligand 5 (CCL5), in RSV-infected human bronchial epithelium BEAS-2B cells. Fluorescent microscopic analysis showed that RSV infection induced autophagosome formation in BEAS-2B cells. This autophagy inducing ability of RSV was further confirmed by flow cytometry. The effects of pharmacological inhibition of autophagy by SAR405 or chloroquine on cell death and cytokine release were quantified using lactate dehydrogenase assay and enzyme-linked immunosorbent assay (ELISA), respectively. We found that SAR405 or chloroquine did not cause cell death. Importantly, ELISA analysis showed that pharmacological inhibition of autophagy by SAR405 or chloroquine did not affect the productions of both CXCL5 and CXCL8. In contrast to the previous studies using mouse model, our data suggest that pharmacological inhibition of autophagy may not be a suitable strategy in controlling RSV-induced airway inflammation.

Control of IFN-I responses by the aminopeptidase IRAP in neonatal C57BL/6 alveolar macrophages during RSV infection

Respiratory Syncytial Virus (RSV) is the major cause of lower respiratory tract infection in infants, in whom, the sensing of RSV by innate immune receptors and its regulation are still poorly described. However, the severe bronchiolitis following RSV infection in neonates has been associated with a defect in type I interferons (IFN-I) production, a cytokine produced mainly by alveolar macrophages (AMs) upon RSV infection in adults. In the present study, neonatal C57BL/6 AMs mobilized very weakly the IFN-I pathway upon RSV infection in vitro and failed to restrain virus replication. However, IFN-I productions by neonatal AMs were substantially increased by the deletion of Insulin-Responsive AminoPeptidase (IRAP), a protein previously involved in the regulation of IFN-I production by dendritic cells. Moreover, neonatal IRAP^KO AMs showed a higher expression of IFN-stimulated genes than their wild-type C57BL/6 counterpart. Interestingly, depletion of IRAP did not affect adult AM responses. Finally, we demonstrated that newborn IRAP^KO mice infected with RSV had more IFN-I in their lungs and eliminated the virus more efficiently than WT neonates. Taken together, early-life susceptibility to RSV infection may be related to an original age-dependent suppressive function of IRAP on the IFN-I driven-antiviral responses in neonatal AMs.

Macrophage-derived cytokines in pneumonia: Linking cellular immunology and genetics

Macrophages represent the first line of anti-pathogen defense - they encounter invading pathogens to perform the phagocytic activity, to deliver the plethora of pro- and anti-inflammatory cytokines, and to shape the tissue microenvironment. Throughout pneumonia course, alveolar macrophages and infiltrated blood monocytes produce increasing cytokine amounts, which activates the antiviral/antibacterial immunity but can also provoke the risk of the so-called cytokine “storm” and normal tissue damage. Subsequently, the question of how the cytokine spectrum is shaped and balanced in the pneumonia context remains a hot topic in medical immunology, particularly in the COVID19 pandemic era. The diversity in cytokine profiles, involved in pneumonia pathogenesis, is determined by the variations in cytokine-receptor interactions, which may lead to severe cytokine storm and functional decline of particular tissues and organs, for example, cardiovascular and respiratory systems. Cytokines and their receptors form unique profiles in individual patients, depending on the (a) microenvironmental context (comorbidities and associated treatment), (b) lung monocyte heterogeneity, and (c) genetic variations. These multidisciplinary strategies can be proactively considered beforehand and during the pneumonia course and potentially allow the new age of personalized immunotherapy.

Lytic Cell Death Mechanisms in Human Respiratory Syncytial Virus-Infected Macrophages: Roles of Pyroptosis and Necroptosis

Human respiratory syncytial virus (RSV) is the most common cause of viral bronchiolitis and pneumonia in infants and children worldwide. Inflammation induced by RSV infection is responsible for its hallmark manifestation of bronchiolitis and pneumonia. The cellular debris created through lytic cell death of infected cells is a potent initiator of this inflammation. Macrophages are known to play a pivotal role in the early innate immune and inflammatory response to viral pathogens. However, the lytic cell death mechanisms associated with RSV infection in macrophages remains unknown. Two distinct mechanisms involved in lytic cell death are pyroptosis and necroptosis. Our studies revealed that RSV induces lytic cell death in macrophages via both of these mechanisms, specifically through the ASC (Apoptosis-associated speck like protein containing a caspase recruitment domain)-NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) inflammasome activation of both caspase-1 dependent pyroptosis and receptor-interacting serine/threonine-protein kinase 3 (RIPK3), as well as a mixed lineage kinase domain like pseudokinase (MLKL)-dependent necroptosis. In addition, we demonstrated an important role of reactive oxygen species (ROS) during lytic cell death of RSV-infected macrophages.

Integrative analysis of microRNA and mRNA expression profiles in MARC-145 cells infected with PRRSV

Porcine reproductive and respiratory syndrome virus (PRRSV) causes tremendous economic losses to the swine industry worldwide. miRNAs are crucial regulators of gene expression and a wide range of complex interactions of miRNAs-mRNAs is possible during virus infection. However, there is no comprehensive integrated study of miRNA and mRNA networks in MARC-145 cells after infection with PRRSV. We analyzed the differential expressions, co-relations, annotations, and putative functions of miRNA and mRNA networks in PRRSV-infected MARC-145 cells. Based on the filtering criterion, 22 differentially expressed miRNAs (DEmiRs) (15 up- and 7 downregulated) were filtered out. miRNA-mRNA interaction networks were constructed. For the 18 selected miRNAs, 390 potential target genes were predicted from the differentially expressed mRNAs (DEmRs). GO and KEGG pathway annotations predicted 34 KEGG pathways, 12 of which are known to be involved in virus infection. Real-time PCR validated the RNA-seq results. Our analysis showed that miR-27a-5p and miR-21-3p downregulate the expression of two of their potential target genes-SPARC, CLIC1, and cofilin-1, COX7A2, respectively. Further experiments proved that miR-21-3p and miR-27a-5p can promote PRRSV replication significantly. It is the first report that these two miRNAs participate in the interaction of host cells with PRRSV. Our results provide insights into the role of miRNAs in response to PRRSV infection, which will aid the research for developing novel therapies against PRRSV.

Interleukin-22 Inhibits Respiratory Syncytial Virus Production by Blocking Virus-Mediated Subversion of Cellular Autophagy

Respiratory syncytial virus (RSV) infection can cause severe bronchiolitis in infants requiring hospitalization, whereas the elderly and immunocompromised are prone to RSV-induced pneumonia. RSV primarily infects lung epithelial cells. Given that no vaccine against RSV is currently available, we tested the ability of the epithelial-barrier protective cytokine interleukin-22 (IL-22) to control RSV production. When used in a therapeutic modality, IL-22 efficiently blunted RSV production from infected human airway and alveolar epithelial cells and IL-22 administration drastically reduced virus titer in the lungs of infected newborn mice. RSV infection resulted in increased expression of LC3B, a key component of the cellular autophagic machinery, and knockdown of LC3B ablated virus production. RSV subverted LC3B with evidence of co-localization and caused a significant reduction in autophagic flux, both reversed by IL-22 treatment. Our findings inform a previously unrecognized anti-viral effect of IL-22 that can be harnessed to prevent RSV-induced severe respiratory disease.

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RSV infection of lung epithelial cells subverts the cellular autophagic machinery

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RSV infection inhibits autophagic flux in infected cells

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IL-22 inhibits RSV production from human lung epithelial cells and in neonatal mice

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IL-22 blocks RSV-LC3B co-localization and restores cellular autophagic flux

IL28A protein homotetramer structure is required for autolysosomal degradation of HCV-NS5A in vitro

Interferon lambda-2 (IL28A) has a wide antiviral effect with fewer side-effects. Autophagy is a host mechanism to maintain intracellular homeostasis and defends invasion of pathogenic microorganisms. HCV NS5A can disable host defense systems to support HCV replication. Thus, molecular mechanism of interaction among interferon lambda, autophagy, and HCV was concerned and explored in this study. We report that HCV NS5A activated an incomplete autophagy by promoting the autophagic ubiquitylation-like enzymes ATG3, ATG5, ATG7, ATG10, and autophagosome maker LC3B, but blocked autophagy flux; IL28A bound to NS5A at NS5A-ISDR region, and degraded HCV-NS5A by promoting autolysosome formations in HepG2 cells. A software prediction of IL28A protein conformation indicated a potential structure of IL28A homotetramer; the first α-helix of IL28A locates in the interfaces among the four IL28A chains to maintain IL28A homotetrameric conformation. Co-IP and cell immunofluorescence experiments with sequential deletion mutants demonstrate that IL28A preferred a homotetramer conformation to a monomer in the cells; the IL28A homotetramer is positively correlated with autolysosomal degradation of HCV NS5A and the other HCV proteins. Summarily, the first α-helix of IL28A protein is the key domain for maintaining IL28A homotetramer which is required for promoting formation of autolysosomes and degradation of HCV proteins in vitro.

Altered Tregs Differentiation and Impaired Autophagy Correlate to Atherosclerotic Disease

Atherosclerosis is a progressive vascular disease representing the primary cause of morbidity and mortality in developed countries. Formerly, atherosclerosis was considered as a mere passive accumulation of lipids in blood vessels. However, it is now clear that atherosclerosis is a complex and multifactorial disease, in which the involvement of immune cells and inflammation play a key role. A variety of studies have shown that autophagy-a cellular catalytic mechanism able to remove injured cytoplasmic components in response to cellular stress-may be proatherogenic. So far, in this context, its role has been investigated in smooth muscle cells, macrophages, and endothelial cells, while the function of this catabolic protective process in lymphocyte functionality has been overlooked. The few studies carried out so far, however, suggested that autophagy modulation in lymphocyte subsets may be functionally related to plaque formation and development. Therefore, in this research, we aimed at better clarifying the role of lymphocyte subsets, mainly regulatory T cells (Tregs), in human atherosclerotic plaques and in animal models of atherosclerosis investigating the contribution of autophagy on immune cell homeostasis. Here, we investigate basal autophagy in a mouse model of atherosclerosis, apolipoprotein E (ApoE)-knockout (KO) mice, and we analyze the role of autophagy in driving Tregs polarization. We observed defective maturation of Tregs from ApoE-KO mice in response to tumor growth factor-β (TGFβ). TGFβ is a well-known autophagy inducer, and Tregs maturation defects in ApoE-KO mice seem to be related to autophagy impairment. In this work, we propose that autophagy underlies Tregs maturation, advocating that the study of this process in atherosclerosis may open new therapeutic strategies.

Determining Immune and miRNA Biomarkers Related to Respiratory Syncytial Virus (RSV) Vaccine Types

Respiratory Syncytial Virus (RSV) causes serious respiratory tract illness and substantial morbidity and some mortality in populations at the extremes of age, i.e., infants, young children, and the elderly. To date, RSV vaccine development has been unsuccessful, a feature linked to the lack of biomarkers available to assess the safety and efficacy of RSV vaccine candidates. We examined microRNAs (miR) as potential biomarkers for different types of RSV vaccine candidates. In this study, mice were vaccinated with a live attenuated RSV candidate that lacks the small hydrophobic (SH) and attachment (G) proteins (CP52), an RSV G protein microparticle (GA2-MP) vaccine, a formalin-inactivated RSV (FI-RSV) vaccine or were mock-treated. Several immunological endpoints and miR expression profiles were determined in mouse serum and bronchoalveolar lavage (BAL) following vaccine priming, boost, and RSV challenge. We identified miRs that were linked with immunological parameters of disease and protection. We show that miRs are potential biomarkers providing valuable insights for vaccine development.

Autophagy induction by the pathogen receptor NECTIN4 and sustained autophagy contribute to peste des petits ruminants virus infectivity

Macroautophagy/autophagy is an essential cellular response in the fight against intracellular pathogens. Although some viruses can escape from or utilize autophagy to ensure their own replication, the responses of autophagy pathways to viral invasion remain poorly documented. Here, we show that peste des petits ruminants virus (PPRV) infection induces successive autophagic signalling in host cells via distinct and uncoupled molecular pathways. Immediately upon invasion, PPRV induced a first transient wave of autophagy via a mechanism involving the cellular pathogen receptor NECTIN4 and an AKT-MTOR-dependent pathway. Autophagic detection showed that early PPRV infection not only increased the amounts of autophagosomes and LC3-II but also downregulated the phosphorylation of AKT-MTOR. Subsequently, we found that the binding of viral protein H to NECTIN4 ultimately induced a wave of autophagy and inactivated the AKT-MTOR pathway, which is a critical step for the control of infection. Soon after infection, new autophagic signalling was initiated that required viral replication and protein expression. Interestingly, expression of IRGM and HSPA1A was significantly upregulated following PPRV replication. Strikingly, knockdown of IRGM and HSPA1A expression using small interfering RNAs impaired the PPRV-induced second autophagic wave and viral particle production. Moreover, IRGM-interacting PPRV-C and HSPA1A-interacting PPRV-N expression was sufficient to induce autophagy through an IRGM-HSPA1A-dependent pathway. Importantly, syncytia formation could facilitate sustained autophagy and the replication of PPRV. Overall, our work reveals distinct molecular pathways underlying the induction of self-beneficial sustained autophagy by attenuated PPRV, which will contribute to improving the use of vaccines for therapy.

Abbreviations: ACTB: actin beta; ANOVA: analysis of variance; ATG: autophagy-related; BECN1: beclin 1; CDV: canine distemper virus; Co-IP: coimmunoprecipitation; FIP: fusion inhibitory peptide; GFP: green fluorescent protein; GST: glutathione S-transferase; HMOX1: heme oxygenase 1; hpi: hours post infection; HSPA1A: heat shock protein family A (Hsp70) member 1A; HSP90AA1: heat shock protein 90 kDa alpha (cytosolic), class A member 1; IFN: interferon; IgG: immunoglobulin G; INS: insulin; IRGM: immunity related GTPase M; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MeV: measles virus; MOI: multiplicity of infection; MTOR: mechanistic target of rapamycin kinase; PI3K: phosphoinositide-3 kinase; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; SDS: sodium dodecyl sulfate; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; UV: ultraviolet.

Immune-Modulation by the Human Respiratory Syncytial Virus: Focus on Dendritic Cells

The human respiratory syncytial virus (hRSV) is the leading cause of pneumonia in infants and produces a significant burden in the elderly. It can also infect and produce disease in otherwise healthy adults and recurrently infect those previously exposed to the virus. Importantly, recurrent infections are not necessarily a consequence of antigenic variability, as described for other respiratory viruses, but most likely due to the capacity of this virus to interfere with the host's immune response and the establishment of a protective and long-lasting immunity. Although some genes encoded by hRSV are known to have a direct participation in immune evasion, it seems that repeated infection is mainly given by its capacity to modulate immune components in such a way to promote non-optimal antiviral responses in the host. Importantly, hRSV is known to interfere with dendritic cell (DC) function, which are key cells involved in establishing and regulating protective virus-specific immunity. Notably, hRSV infects DCs, alters their maturation, migration to lymph nodes and their capacity to activate virus-specific T cells, which likely impacts the host antiviral response against this virus. Here, we review and discuss the most important and recent findings related to DC modulation by hRSV, which might be at the basis of recurrent infections in previously infected individuals and hRSV-induced disease. A focus on the interaction between DCs and hRSV will likely contribute to the development of effective prophylactic and antiviral strategies against this virus.

Autophagy enhances the replication of Peste des petits ruminants virus and inhibits caspase-dependent apoptosis in vitro

Peste des petits ruminants (PPR) is an acute and highly contagious disease in small ruminants that causes significant economic losses in developing countries. An increasing number of studies have demonstrated that both autophagy and apoptosis are important cellular mechanisms for maintaining homeostasis, and they participate in the host response to pathogens. However, the crosstalk between apoptosis and autophagy in host cells during PPRV infection has not been clarified. In this study, autophagy was induced upon virus infection in caprine endometrial epithelial cells (EECs), as determined by the appearance of double- and single-membrane autophagy-like vesicles, LC3-I/LC3-II conversion, and p62 degradation. We also found that PPRV infection triggered a complete autophagic response, most likely mediated by the non-structural protein C and nucleoprotein N. Moreover, our results suggest that autophagy not only promotes the replication of PPRV in EECs but also provides a potential mechanism for inhibiting PPRV-induced apoptosis. Inhibiting autophagosome formation by wortmannin and knocking down the essential autophagic proteins Beclin-1 and ATG7 induces caspase-dependent apoptosis in EECs in PPRV infection. However, inhibiting autophagosome and lysosome fusion by NH₄Cl and chloroquine did not increase the number of apoptotic cells. Collectively, these data are the first to indicate that PPRV-induced autophagy inhibits caspase-dependent apoptosis and thus contributes to the enhancement of viral replication and maturity in host cells.

Respiratory Syncytial Virus Replication Is Promoted by Autophagy-Mediated Inhibition of Apoptosis

Respiratory syncytial virus (RSV) is the main cause of acute lower respiratory tract infection (ALRI) in children worldwide. Virus-host interactions affect the progression and prognosis of the infection. Autophagy plays important roles in virus-host interactions. Respiratory epithelial cells serve as the front line of host defense during RSV infection, However, it is still unclear how they interact with RSV. In this study, we found that RSV induced autophagy that favored RSV replication and exacerbated lung pathology in vivo Mechanistically, RSV induced complete autophagy flux through reactive oxygen species (ROS) generation and activation of the AMP-activated protein kinase/mammalian target of rapamycin (AMPK-MTOR) signaling pathway in HEp-2 cells. Furthermore, we evaluated the functions of autophagy in RSV replication and found that RSV replication was increased in HEp-2 cells treated with rapamycin but decreased remarkably in cells treated with 3-methylademine (3-MA) or wortmannin. Knockdown key molecules in the autophagy pathway with short hairpinp RNA (shRNA) against autophagy-related gene 5 (ATG5), autophagy-related gene 7 (ATG7), or BECN1/Beclin 1 or treatment with ROS scavenger N-acetyl-l-cysteine (NAC) and AMPK inhibitor (compound C) suppressed RSV replication. 3-MA or shATG5/BECN1 significantly decreased cell viability and increased cell apoptosis at 48 hours postinfection (hpi). Blocking apoptosis with Z-VAD-FMK partially restored virus replication at 48 hpi. Those results provide strong evidence that autophagy may function as a proviral mechanism in a cell-intrinsic manner during RSV infection.IMPORTANCE An understanding of the mechanisms that respiratory syncytial virus utilizes to interact with respiratory epithelial cells is critical to the development of novel antiviral strategies. In this study, we found that RSV induces autophagy through a ROS-AMPK signaling axis, which in turn promotes viral infection. Autophagy favors RSV replication through blocking cell apoptosis at 48 hpi. Mechanistically, RSV induces mitophagy, which maintains mitochondrial homeostasis and therefore decreases cytochrome c release and apoptosis induction. This study provides a novel insight into this virus-host interaction, which may help to exploit new antiviral treatments targeting autophagy processes.

Viruses as key modulators of the TGF-β pathway; a double-edged sword involved in cancer

Transforming growth factor-β (TGF-β) signaling pathway is a key network in cell signaling that controls vital processes such as proliferation, differentiation, apoptosis, epithelial-mesenchymal transition, and migration, thus acting as a double-edged sword in normal development and diseases, in particular organ fibrosis, vascular disorders, and cancer. Early in tumorigenesis, the pathway exerts anti-tumor effects through suppressing cell cycle and inducing apoptosis, while during late stages, it functions as a tumor promoter by enhancing tumor invasiveness and metastasis. This signaling pathway can be perturbed by environmental and genetic factors such as microbial interference and mutation, respectively. In this way, the present review describes the modulation of the TGF-β pathway by oncogenic human viral pathogens and other viruses. The main mechanisms by which viruses interferes with TGF-β signaling seems to be through (1) the alteration of either TGF-β protein expression or activation, (2) the modulation of the TGF-β receptors or SMADs factors (by interfering with their levels and functions), (3) the alteration of none-SMAD pathways, and (4) indirect interaction with the pathway by the modulation of transcriptional co-activator/repressor and regulators of the pathway. Given the axial role of this pathway in tumorigenesis, it can be regarded as an attractive target for cancer therapy. Hence, further investigations on this subject may represent molecular targets among either TGF-β signaling molecules or viral factors for the treatment and management of viral infection consequences such as cancer.

Phosphoproteomic analysis reveals Smad protein family activation following Rift Valley fever virus infection

Rift Valley fever virus (RVFV) infects both ruminants and humans leading to a wide variance of pathologies dependent on host background and age. Utilizing a targeted reverse phase protein array (RPPA) to define changes in signaling cascades after in vitro infection of human cells with virulent and attenuated RVFV strains, we observed high phosphorylation of Smad transcription factors. This evolutionarily conserved family is phosphorylated by and transduces the activation of TGF-β superfamily receptors. Moreover, we observed that phosphorylation of Smad proteins required active RVFV replication and loss of NSs impaired this activation, further corroborating the RPPA results. Gene promoter analysis of transcripts altered after RVFV infection identified 913 genes that contained a Smad-response element. Functional annotation of these potential Smad-regulated genes clustered in axonal guidance, hepatic fibrosis and cell signaling pathways involved in cellular adhesion/migration, calcium influx, and cytoskeletal reorganization. Furthermore, chromatin immunoprecipitation confirmed the presence of a Smad complex on the interleukin 1 receptor type 2 (IL1R2) promoter, which acts as a decoy receptor for IL-1 activation.

The clinical and biological roles of transforming growth factor beta in colon cancer stem cells: A systematic review

BACKGROUND

Transforming growth factor beta (TGF-β) is a multipurpose cytokine, which plays a role in many cellular functions such as proliferation, differentiation, migration, apoptosis, cell adhesion and regulation of epithelial to mesenchymal transition. Despite many studies having observed the effect that TGF-β plays in colorectal cancer, its role in the colorectal stem cell population has not been widely observed.

METHOD

This systematic review will analyse the role of TGF-β in the stem cell population of colorectal cancer.

RESULTS

The effects on the stem cell phenotype are through the downstream proteins involved in activation of the TGF-β pathway. Its involvement in the initiation of the epithelial to mesenchymal transition (EMT), the effect of colorectal invasion and metastasis regulated through the Smad protein involvement in the EMT, initiation of angiogenesis, promotion of metastasis of colorectal cancer to the liver and its ability to cross-talk with other pathways.

CONCLUSION

TGF-β is a key player in angiogenesis, tumour growth and metastasis in colon cancer.

Lethal concentration of perfluoroisobutylene induces acute lung injury in mice mediated via cytokine storm, oxidative stress and apoptosis

Perfluoroisobutylene (PFIB) is a highly toxic gas that targets the lungs. Low-level inhalation of the gas can lead to acute lung injury (ALI), pulmonary edema and even death. No specific anti-PFIB drugs are currently available and the pathogenesis of PFIB-induced ALI is not fully understood. Early direct oxidative injury and a secondary hyper-inflammatory response are recognized as the primary mechanisms of PFIB-induced ALI. In the present study, our data demonstrate for the first time that a cytokine storm is associated with PFIB-induced ALI. Levels of 10 pro-inflammatory cytokines and one anti-inflammatory cytokine were significantly increased in lung tissues of PFIB-exposed mice. PFIB inhalation additionally led to significant oxidative stress in lung tissue. Inflammation-associated CD11b⁺Ly6G⁺Ly6C^int neutrophils and CD11b⁺Ly6G^-Ly6C^hi monocytes were significantly increased in blood in association with PFIB-induced ALI. Bcl-2/Bax-mediated lung cell apoptosis was significantly increased at 1 h, followed by a sustained decrease after 1 h, which was significant at 4-8 h in PFIB-exposed mice. This suppression of apoptosis is possibly associated with the Akt-signaling pathway.

Apoptosis, Toll-like, RIG-I-like and NOD-like Receptors Are Pathways Jointly Induced by Diverse Respiratory Bacterial and Viral Pathogens

Lower respiratory tract infections are among the top five leading causes of human death. Fighting these infections is therefore a world health priority. Searching for induced alterations in host gene expression shared by several relevant respiratory pathogens represents an alternative to identify new targets for wide-range host-oriented therapeutics. With this aim, alveolar macrophages were independently infected with three unrelated bacterial (Streptococcus pneumoniae, Klebsiella pneumoniae, and Staphylococcus aureus) and two dissimilar viral (respiratory syncytial virus and influenza A virus) respiratory pathogens, all of them highly relevant for human health. Cells were also activated with bacterial lipopolysaccharide (LPS) as a prototypical pathogen-associated molecular pattern. Patterns of differentially expressed cellular genes shared by the indicated pathogens were searched by microarray analysis. Most of the commonly up-regulated host genes were related to the innate immune response and/or apoptosis, with Toll-like, RIG-I-like and NOD-like receptors among the top 10 signaling pathways with over-expressed genes. These results identify new potential broad-spectrum targets to fight the important human infections caused by the bacteria and viruses studied here.