Interference with intraepithelial TNF-α signaling inhibits CD8(+) T-cell-mediated lung injury in influenza infection

Mechanisms underlying the therapeutic effects of Gang Huo Qing wen granules in the treatment of influenza based on network pharmacology, molecular docking and molecular dynamics

Influenza (Flu) is a severe health, medical, and economic problem, but no medication that has excellent outcomes and lowers the occurrence of these problems is now available. GanghuoQingwenGranules (GHQWG) is a common Chinese herbal formula for the treatment of influenza (flu). However, its methods of action remain unknown. We used network pharmacology, molecular docking, and molecular dynamics simulation techniques to investigate the pharmacological mechanism of GHQWG in flu. TCMSP and various types of literature were used to obtain active molecules and targets of GHQWG. Flu-related targets were found in the Online Mendelian Inheritance in Man (OMIM) database, the DisFeNET database, the Therapeutic Target Database (TTD), and the DrugBank database. To screen the key targets, a protein-protein interaction (PPI) network was constructed. DAVID was used to analyze GO and KEGG pathway enrichment. Target tissue and organ distribution was assessed. Molecular docking was used to evaluate interactions between possible targets and active molecules. For the ideal core protein-compound complexes obtained using molecular docking, a molecular dynamics simulation was performed. In total, 90 active molecules and 312 GHQWG targets were discovered. The PPI network's topology highlighted six key targets. GHQWG's effects are mediated via genes involved in inflammation, apoptosis, and oxidative stress, as well as the TNF and IL-17 signaling pathways, according to GO and KEGG pathway enrichment analysis. Molecular docking and molecular dynamics simulations demonstrated that the active compounds and tested targets had strong binding capabilities. This analysis accurately predicts the effective components, possible targets, and pathways involved in GHQWG flu treatment. We proposed a novel study strategy for future studies on the molecular processes of GHQWG in flu treatment. Furthermore, the possible active components provide a dependable source for flu drug screening.

Adenoviral-vectored universal influenza vaccines administered intranasally reduce lung inflammatory responses upon viral challenge 15 months post-vaccination

IMPORTANCE

Vaccines targeting highly conserved proteins can protect broadly against diverse viral strains. When a vaccine is administered to the respiratory tract, protection against disease is especially powerful. However, it is important to establish that this approach is safe. When vaccinated animals later encounter viruses, does reactivation of powerful local immunity, including T cell responses, damage the lungs? This study investigates the safety of mucosal vaccination of the respiratory tract. Non-replicating adenoviral vaccine vectors expressing conserved influenza virus proteins were given intranasally. This vaccine-induced protection persists for at least 15 months. Vaccination did not exacerbate inflammatory responses or tissue damage upon influenza virus infection. Instead, vaccination with nucleoprotein reduced cytokine responses and histopathology, while neutrophil and T cell responses resolved earlier. The results are promising for safe vaccination at the site of infection and thus have implications for the control of influenza and other respiratory viruses.

Viral PB1-F2 and host IFN-γ guide ILC2 and T cell activity during influenza virus infection

The regulation of functional immune cell plasticity is poorly understood. Host environmental cues are critical, but the possible influence of pathogen-derived virulence factors has not been described. We have used reverse-engineered influenza A viruses that differ in PB1-F2 activity to analyze influenza in mice in the presence or absence of host interferon (IFN)-γ. In the absence of functional PB1-F2 and IFN-γ, lung ILC2s initiated robust IL-5 responses following viral challenge, which led to improved tissue integrity and survival. Conversely, functional PB1-F2 suppressed IL-5⁺ ILC2 responses and induced a dominant IL-13⁺ CD8 T cell response regardless of host IFN-γ. These findings demonstrate the critical interplay between the viral virulence factors and host cytokines in regulating protective pulmonary immunity during influenza virus infection.

Functional plasticity of innate lymphoid cells (ILCs) and T cells is regulated by host environmental cues, but the influence of pathogen-derived virulence factors has not been described. We now report the interplay between host interferon (IFN)-γ and viral PB1-F2 virulence protein in regulating the functions of ILC2s and T cells that lead to recovery from influenza virus infection of mice. In the absence of IFN-γ, lung ILC2s from mice challenged with the A/California/04/2009 (CA04) H1N1 virus, containing nonfunctional viral PB1-F2, initiated a robust IL-5 response, which also led to improved tissue integrity and increased survival. Conversely, challenge with Puerto Rico/8/1934 (PR8) H1N1 virus expressing fully functional PB1-F2, suppressed IL-5⁺ ILC2 responses, and induced a dominant IL-13⁺ CD8 T cell response, regardless of host IFN-γ expression. IFN-γ–deficient mice had increased survival and improved tissue integrity following challenge with lethal doses of CA04, but not PR8 virus, and increased resistance was dependent on the presence of IFN-γR⁺ ILC2s. Reverse-engineered influenza viruses differing in functional PB1-F2 activity induced ILC2 and T cell phenotypes similar to the PB1-F2 donor strains, demonstrating the potent role of viral PB1-F2 in host resistance. These results show the ability of a pathogen virulence factor together with host IFN-γ to regulate protective pulmonary immunity during influenza infection.

Regulation of Lysosomal Associated Membrane Protein 3 (LAMP3) in Lung Epithelial Cells by Coronaviruses (SARS-CoV-1/2) and Type I Interferon Signaling

Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) infection is a major risk factor for mortality and morbidity in critical care hospitals around the world. Lung epithelial type II cells play a major role in the recognition and clearance of respiratory viruses as well as repair of lung injury in response to environmental toxicants. Gene expression profiling studies revealed that mouse lung epithelial type II cells express several cell-specific markers including surfactant proteins and Lysosomal associated membrane protein 3 (LAMP3) located in lysosomes, endosomes and lamellar bodies. These intracellular organelles are involved in vesicular transport and facilitate viral entry and release of the viral genome into the host cell cytoplasm. In this study, regulation of LAMP3 expression in human lung epithelial cells by several respiratory viruses and type I interferon signaling was investigated. Respiratory viruses including SARS-CoV-1 and SARS-CoV-2 significantly induced LAMP3 expression in lung epithelial cells within 24 hours after infection that required the presence of ACE2 viral entry receptors. Time course experiments revealed that the induced expression of LAMP3 was correlated with the induced expression of Interferon–beta (IFNB1) and STAT1 at mRNA levels. LAMP3 was also induced by direct IFN-beta treatment in multiple lung epithelial cell lines or by infection with influenza virus lacking the non-structural protein1(NS1) in NHBE bronchial epithelial cells. LAMP3 expression was also induced by several respiratory viruses in human lung epithelial cells including RSV and HPIV3. Location in lysosomes and endosomes aswell as induction by respiratory viruses and type I Interferon suggests that LAMP3 may have an important role in inter-organellar regulation of innate immunity and a potential target for therapeutic modulation in health and disease. Furthermore, bioinformatics revealed that a subset of lung type II genes were differentially regulated in the lungs of COVID-19 patients.

Regulation of early growth response-1 (Egr-1) gene expression by Stat1-independent type I interferon signaling and respiratory viruses

Respiratory virus infection is one of the leading causes of death in the world. Activation of the Jak-Stat pathway by Interferon-alpha/beta (IFN-α/β) in lung epithelial cells is critical for innate immunity to respiratory viruses. Transcriptional factor profiling in the transcriptome and RNA analysis revealed that Early growth response-1 (EGR1/Egr-1) was rapidly induced by IFN-α/β and Toll-like receptor (TLR) ligands in multiple cell types. Studies in mutant cell lines lacking components of the interferon-stimulated gene factor complex (ISGF-3) revealed that IFN-β induction of Egr-1 was independent of Stat1, Stat2, or Irf9. Activation of the Mek/Erk-1/2 pathway was implicated in the rapid induction of Egr-1 by IFN-β in serum-starved mouse lung epithelial cells. Interrogation of multiple microarray datasets revealed that respiratory viruses including coronaviruses induced IFN-β and regulated Egr-1 expression in human lung cell lines. Furthermore, bioinformatic analysis revealed that type I interferon-stimulated genes and Egr-1 inducible genes including transcription factors, mediators of cell growth, and chemokines were differentially regulated in the human lung cell lines after coronavirus infection, and in the lung biopsies of COVID-19 patients.

Impact of influenza syndrome and flu vaccine on survival of cancer patients during immunotherapy in the INVIDIa study

Aim: INVIDIa was a retrospective, multicenter study, exploring the clinical efficacy of influenza vaccine in 300 cancer patients undergoing immunotherapy. Overall survival (OS) was immature at the initial report. Methods: We reported the final OS analysis from the original study population and within subgroups. Results: Both at the univariate and multivariate analysis, the occurrence of influenza syndrome (IS) was significantly related to better OS in the overall population (OR: 0.53 [95% CI: 0.32-0.88]; p = 0.01). In the lung cancer subgroup, receiving flu vaccine and/or developing IS was related to better OS (p = 0.04). Within elderly patients, the flu vaccine was the main variable for the relative OS advantage (p = 0.05). Conclusion: Receiving the flu vaccine and/or developing IS was related to better OS within the INVIDIa population.

INfluenza Vaccine Indication During therapy with Immune checkpoint inhibitors: a transversal challenge. The INVIDIa study

AIM

Considering the unmet need for the counseling of cancer patients treated with immune checkpoint inhibitors (CKI) about influenza vaccination, an explorative study was planned to assess flu vaccine efficacy in this population.

METHODS

INVIDIa was a retrospective, multicenter study, enrolling consecutive advanced cancer outpatients receiving CKI during the influenza season 2016-2017.

RESULTS

Of 300 patients, 79 received flu vaccine. The incidence of influenza syndrome was 24.1% among vaccinated, versus 11.8% of controls; odds ratio: 2.4; 95% CI: 1.23-4.59; p = 0.009. The clinical ineffectiveness of vaccine was more pronounced among elderly: 37.8% among vaccinated patients, versus 6.1% of unvaccinated, odds ratio: 9.28; 95% CI: 2.77-31.14; p < 0.0001.

CONCLUSION

Although influenza vaccine may be clinically ineffective in advanced cancer patients receiving CKI, it seems not to negatively impact the efficacy of anticancer therapy.

Human CD8+ T Cells Damage Noninfected Epithelial Cells during Influenza Virus Infection In Vitro

During severe influenza A virus (IAV) infections, a large amount of damage to the pulmonary epithelium is the result of the antiviral immune response. Specifically, whilst CD8⁺ T cells are important for killing IAV-infected cells, during a severe IAV infection, they can damage uninfected epithelial cells. At present, the mechanisms by which this occurs are unclear. Here, we used a novel in vitro coculture model of human NCl-H441 cells and CD8⁺ T cells to provide a new insight into how CD8⁺ T cells may affect uninfected epithelial cells during severe IAV infections. Using this model, we show that human IAV-specific CD8⁺ T cells produce soluble factors that reduce the barrier integrity of noninfected epithelial cells (referred to as "bystander damage"). We show that this bystander damage is the result of a combination of TNF-α and IFN-γ. This bystander damage occurred in the absence of widespread epithelial cell death and was instead associated with decreased expression of epithelial cell ion channels and pumps. Together, these data suggest that ameliorating the function of epithelial cell ion channels and pumps may help reduce immunopathology during severe IAV infections.

Balancing Immune Protection and Immune Pathology by CD8(+) T-Cell Responses to Influenza Infection

Influenza A virus (IAV) is a significant human pathogen causing annual epidemics and periodic pandemics. CD8⁺ cytotoxic T lymphocyte (CTL)-mediated immunity contributes to the clearance of virus-infected cells, and CTL immunity targeting the conserved internal proteins of IAVs is a key protection mechanism when neutralizing antibodies are absent during heterosubtypic IAV infection. However, CTL infiltration into the airways, its cytotoxicity, and the effects of produced proinflammatory cytokines can cause severe lung tissue injury, thereby contributing to immunopathology. Studies have discovered complicated and exquisite stimulatory and inhibitory mechanisms that regulate CTL magnitude and effector activities during IAV infection. Here, we review the state of knowledge on the roles of IAV-specific CTLs in immune protection and immunopathology during IAV infection in animal models, highlighting the key findings of various requirements and constraints regulating the balance of immune protection and pathology involved in CTL immunity. We also discuss the evidence of cross-reactive CTL immunity as a positive correlate of cross-subtype protection during secondary IAV infection in both animal and human studies. We argue that the effects of CTL immunity on protection and immunopathology depend on multiple layers of host and viral factors, including complex host mechanisms to regulate CTL magnitude and effector activity, the pathogenic nature of the IAV, the innate response milieu, and the host historical immune context of influenza infection. Future efforts are needed to further understand these key host and viral factors, especially to differentiate those that constrain optimally effective CTL antiviral immunity from those necessary to restrain CTL-mediated non-specific immunopathology in the various contexts of IAV infection, in order to develop better vaccination and therapeutic strategies for modifying protective CTL immunity.

Tissue-protective effects of NKG2A in immune-mediated clearance of virus infection

Virus infection triggers a CD8⁺ T cell response that aids in virus clearance, but also expresses effector functions that may result in tissue injury. CD8⁺ T cells express a variety of activating and inhibiting ligands, though regulation of the expression of inhibitory receptors is not well understood. The ligand for the inhibitory receptor, NKG2A, is the non-classical MHC-I molecule Qa1^b, which may also serve as a putative restricting element for the T cell receptors of purported regulatory CD8⁺ T cells. We have previously shown that Qa1^b-null mice suffer considerably enhanced immunopathologic lung injury in the context of CD8⁺ T cell-mediated clearance of influenza infection, as well as evidence in a non-viral system that failure to ligate NKG2A on CD8⁺ effector T cells may represent an important component of this process. In this report, we examine the requirements for induction of NKG2A expression, and show that NKG2A expression by CD8⁺ T cells occurs as a result of migration from the MLN to the inflammatory lung environment, irrespective of peripheral antigen recognition. Further, we confirmed that NKG2A is a mediator in limiting immunopathology in virus infection using mice with a targeted deletion of NKG2A, and infecting the mutants with two different viruses, influenza and adenovirus. In neither infection is virus clearance altered. In influenza infection, the enhanced lung injury was associated with increased chemoattractant production, increased infiltration of inflammatory cells, and significantly enhanced alveolar hemorrhage. The primary mechanism of enhanced injury was the loss of negative regulation of CD8⁺ T cell effector function. A similar effect was observed in the livers of mutant mice infected intravenously with adenovirus. These results demonstrate the immunoregulatory role of CD8⁺ NKG2A expression in virus infection, which negatively regulates T cell effector functions and contributes to protection of tissue integrity during virus clearance.

Plasmacytoid dendritic cells mediate the regulation of inflammatory type T cell response for optimal immunity against respiratory Chlamydia pneumoniae infection

Chlamydia pneumoniae (Cpn) infection is a leading cause for a variety of respiratory diseases and has been implicated in the pathogenesis of chronic inflammatory diseases. The regulatory mechanisms in host defense against Cpn infection are less understood. In this study, we investigated the role of plasmacytoid dendritic cells (pDCs) in immune regulation in Cpn respiratory tract infection. We found that in vivo depletion of pDCs increased the severity of infection and lung pathology. Mice depleted of pDC had greater body weight loss, higher lung bacterial burden and excessive tissue inflammation compared to the control mice. Analysis of specific T cell cytokine production pattern in the lung following Cpn infection revealed that pDC depleted mice produced significantly higher amounts of inflammatory cytokines, especially TNF-α, but lower IL-10 compared to the controls. In particular, pDC depleted mice showed pathogenic T cell responses characterized by inflammatory type-1 (CD8 and CD4) and inflammatory Th2 cell responses. Moreover, pDC depletion dramatically reduced CD4 regulatory T cells (Tregs) in the lungs and draining lymph nodes. Furthermore, pDC-T cell co-culture experiments showed that pDCs isolated from Cpn infected mice were potent in inducing IL-10 producing CD4 Tregs. Together, these findings provide in vivo evidence for a critical role of pDCs in homeostatic regulation of immunity during Cpn infection. Our findings highlight the importance of a ‘balanced’ immune response for host protective immunity and preventing detrimental immunopathology during microbial infections.

STAT1 interaction with E3-14.7K in monocytes affects the efficacy of oncolytic adenovirus

Oncolytic viruses based on adenovirus type 5 (Ad5) have been developed as a new class of therapeutic agents for cancers that are resistant to conventional therapies. Clinical experience shows that these agents are safe, but virotherapy alone has not achieved long-term cure in cancer patients. The vast majority of oncolytic adenoviruses used in clinical trials to date have deletion of the E3B genes. It has been demonstrated that the antitumor potency of the E3B-deleted mutant (dl309) is inferior to adenovirus with E3B genes intact. Tumors treated with dl309 show markedly greater macrophage infiltration than E3B-intact adenovirus. However, the functional mechanisms for this were not previously known. Here, we demonstrate that deletion of E3B genes increases production of chemokines by monocytes after adenovirus infection and increases monocyte migration. The E3B 14,700-Da protein (E3B-14.7K) inhibits STAT1 function by preventing its phosphorylation and nuclear translocation. The STAT1 inhibitor, fludarabine, rescues the effect of E3B-14.7K deletion by downregulating target chemokine expression in human and murine monocytes and results in an enhanced antitumor efficacy with dl309 in vivo. These findings have important implications for clinical use of E3B-deleted oncolytic adenovirus and other E3B-deleted adenovirus vector-based therapy.

Clearance of influenza virus infections by T cells: risk of collateral damage?

Influenza A viruses are a major cause of respiratory infections in humans. To protect against influenza, vaccines mainly aim at the induction of antibodies against the two surface proteins and do not protect against influenza A viruses from other subtypes. There is an increasing interest in heterosubtypic immunity that does protect against different subtypes. CD8 and CD4 T cells have a beneficial effect on the course of influenza A virus infection and can recognize conserved IAV epitopes. The T cell responses are tightly regulated to avoid collateral damage due to overreaction. Different studies have shown that an aberrant T cell response to an influenza virus infection could be harmful and could contribute to immunopathology. Here we discuss the recent findings on the balance between the beneficial and detrimental effects of T cell responses in influenza virus infections.

An oligodeoxynucleotide capable of lessening acute lung inflammatory injury in mice infected by influenza virus

Infection of influenza virus could induce acute lung inflammatory injury (ALII) that was at least partially caused by excessive innate immune responses. To study whether down-regulating Toll-like receptor (TLR)-mediated innate immune response could lessen influenza virus-induced ALII, a microsatellite DNA mimicking oligodeoxynucleotide (MS ODN), named as SAT05f capable of inhibiting TLR7/9-activation in vitro, was used to treat mice infected with FM1 virus. In parallel, two MS ODNs confirmed with less or no in vitro activities, named as MS19 and MS33, were used as controls. Unexpectedly, SAT05f failed to lessen ALII in the mice, whereas MS19 significantly inhibited the weight loss and displayed dramatic effect on lessening the ALII by reducing consolidation, hemorrhage, intra-alveolar edema and neutrophils infiltration in lungs of the mice. Meanwhile, MS19 could decrease the mortality of influenza virus infected mice and down-regulate TNF-α production in their lungs. The data suggest that MS19 might display its therapeutic role on ALII induced by influenza virus by reducing over-production of TNF-α.

Use of plethysmography in assessing the efficacy of antivirals in a mouse model of pandemic influenza A virus

The recently emerged swine-origin H1N1 influenza A virus (IAV) caused a pandemic outbreak in 2009 with higher risk of severe disease among children and pregnant women in their third trimester (Van Kerkhove et al., 2011), and is continuing to be important seasonal IAV strain. Mice are commonly used in antiviral studies as models of influenza disease, which utilize morbidity and mortality to assess the efficacy of a test compound. Here, we investigated the utility of unrestrained plethysomography to quantify the lung function of IAV-infected BALB/c mice. Administration of a lethal dose (∼30X LD(50)) of pandemic H1N1 IAV resulted in a rapid decline in breath volume, as determined by a significant (P<0.001) decrease in the pressure associated with inspiration and expiration detected as early as 2 days after virus challenge. Severe disease was also accompanied by a significant (P<0.05) increase in breath time on 8 dpi. Plethysmography parameters correlated with weight loss and other parameters of disease such as gross pathology and the weight of the lung. Breath time was reduced in surviving mice challenged with a sublethal dose of virus as compared with normal controls, and is a predictive indicator of outcome in these mice. In antiviral studies, the use of plethysmography resulted in the detection of a clear and rapid treatment response, which was similar to other non-invasive parameters, such as weight change. Oseltamivir and ribavirin significantly (P<0.001) improved parameters of lung function, particularly mean breath volume, as early as 2 dpi and in a dose-dependent manner. Moreover, a combination of these two drugs further improved these parameters. Plethysmography provides a sensitive evaluation of lung function in IAV-infected mice in response to antiviral therapy.