Innate Immune Responses Of Type I Alveolar Epithelial Cells During Pneumonia

The most severe complication of influenza is viral pneumonia, which can lead to the acute respiratory distress syndrome. Alveolar epithelial cells (AECs) are the first cells that influenza virus encounters upon entering the alveolus. Infected epithelial cells produce cytokines that attract and activate neutrophils and macrophages, which in turn induce damage to the epithelial-endothelial barrier. Hepatocyte growth factor (HGF)/c-Met and transforming growth factor-α (TGF-α)/epidermal growth factor receptor (EGFR) are well known to regulate repair of damaged alveolar epithelium by stimulating cell migration and proliferation. Recently, TGF-α/EGFR signaling has also been shown to regulate innate immune responses in bronchial epithelial cells. However, little is known about whether HGF/c-Met signaling alters the innate immune responses and whether the innate immune responses in AECs are regulated by HGF/c-Met and TGF-α/EGFR. We hypothesized that HGF/c-Met and TGF-α/EGFR would regulate innate immune responses to influenza A virus infection in human AECs. We found that recombinant human HGF (rhHGF) and rhTGF-α stimulated primary human AECs to secrete IL-8 and granulocyte macrophage colony-stimulating factor (GM-CSF) strongly and IL-6 and monocyte chemotactic protein 1 moderately. Influenza infection stimulated the secretion of IL-8 and GM-CSF by AECs plated on rat-tail collagen through EGFR activation likely by TGF-α released from AECs and through c-Met activated by HGF secreted from lung fibroblasts. HGF secretion by fibroblasts was stimulated by AEC production of prostaglandin E2 during influenza infection. We conclude that HGF/c-Met and TGF-α/EGFR signaling enhances the innate immune responses by human AECs during influenza infections.

Download Full-text

Host signaling and proteolytic pathways in the resolution or the exacerbation of coronavirus (CoV-2) infection in COVID-19 disease: what therapeutic targets?

10.31219/osf.io/rtfmx ◽

2020 ◽

Cited By ~ 1

Author(s):

Jean-Michel SALLENAVE ◽

Loic Guillot

Keyword(s):

Immune Responses ◽

Serine Proteases ◽

Multiple Organ ◽

Innate Immune ◽

Alveolar Epithelial Cells ◽

Innate Immune Responses ◽

Dipeptidyl Peptidase 4 ◽

Alveolar Epithelial ◽

Enveloped Virus ◽

Host Signaling

COVID-19 is caused by the Severe Acute Respiratory Syndrome (SARS) coronavirus (Cov)-2, an enveloped virus with a positive single-stranded RNA genome. Pandemic initial outbreak began in December 2019 and is threatening the health of the global community. In common with previous pandemics (Influenza H1N1, SARS-CoV-1) and the epidemics of Middle east respiratory syndrome (MERS)-CoV, CoVs target bronchial and alveolar epithelial cells. Virus proteins ligands (eg haemagglutinin or spike protein for Influenza and CoV, respectively) interact with cellular receptors such as (depending on the virus), either sialic acids, Dipeptidyl peptidase 4 (DPP4), or angiotensin-converting enzyme 2 (ACE2). Host proteases, eg cathepsins, furin, or members of the type II transmembrane serine proteases (TTSP) family such as Transmembrane protease serine 2 (TMPRSS2) are involved in virus entry by proteolytically activating virus ligands. Also involved are Toll Like Receptor (TLR) familly members which up-regulate anti-viral and pro-inflammatory mediators (interleukin (IL)-6 and IL-8...), through the activation of Nuclear Factor (NF)-kB. When these events (virus cellular entry and innate immune responses) are uncontrolled, a deleterious systemic response is sometimes encountered in infected patients, leading to the well described ‘cytokine storm’ and an ensuing multiple organ failure, promoted by a down-regulation of dendritic cells, macrophage and T cell function.We aim to describe how the lung and systemic host innate immune responses affect survival either positively, through down-regulating initial viral load, or negatively, by triggering uncontrolled inflammation. An emphasis will be put on host cellular signaling pathways and proteases involved, with a view on tackling these therapeutically.

Download Full-text

Disparate cytokine regulation of ICAM-1 in rat alveolar epithelial cells and pulmonary endothelial cells in vitro

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1995.269.1.l127 ◽

1995 ◽

Vol 269 (1) ◽

pp. L127-L135 ◽

Cited By ~ 5

Author(s):

W. W. Barton ◽

S. Wilcoxen ◽

P. J. Christensen ◽

R. Paine

Keyword(s):

Endothelial Cells ◽

Epithelial Cells ◽

Inflammatory Cytokines ◽

Alveolar Epithelial Cells ◽

Normal Lung ◽

Type I ◽

Type Ii Cells ◽

Type Ii ◽

Alveolar Epithelial

Intercellular adhesion molecule-1 (ICAM-1) is expressed at high levels on type I alveolar epithelial cells in the normal lung and is induced in vitro as type II cells spread in primary culture. In contrast, in most nonhematopoetic cells ICAM-1 expression is induced in response to inflammatory cytokines. We have formed the hypothesis that the signals that control ICAM-1 expression in alveolar epithelial cells are fundamentally different from those controlling expression in most other cells. To test this hypothesis, we have investigated the influence of inflammatory cytokines on ICAM-1 expression in isolated type II cells that have spread in culture and compared this response to that of rat pulmonary artery endothelial cells (RPAEC). ICAM-1 protein, determined both by a cell-based enzyme-linked immunosorbent assay and by Western blot analysis, and mRNA were minimally expressed in unstimulated RPAEC but were significantly induced in a time- and dose-dependent manner by treatment with tumor necrosis factor-alpha, interleukin-1 beta, or interferon-gamma. In contrast, these cytokines did not influence the constitutive high level ICAM-1 protein expression in alveolar epithelial cells and only minimally affected steady-state mRNA levels. ICAM-1 mRNA half-life, measured in the presence of actinomycin D, was relatively long at 7 h in alveolar epithelial cells and 4 h in RPAEC. The striking lack of response of ICAM-1 expression by alveolar epithelial cells to inflammatory cytokines is in contrast to virtually all other epithelial cells studied to date and supports the hypothesis that ICAM-1 expression by these cells is a function of cellular differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Intrinsic pollen NADPH oxidases induce genes by activating innate immune responses in human bronchial epithelial cells*1

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2004.01.694 ◽

2004 ◽

Vol 113 (2) ◽

pp. S330

Author(s):

R BLOEBAUM

Keyword(s):

Epithelial Cells ◽

Immune Responses ◽

Bronchial Epithelial Cells ◽

Innate Immune ◽

Innate Immune Responses ◽

Human Bronchial Epithelial Cells ◽

Nadph Oxidases ◽

Bronchial Epithelial

Download Full-text

The Sp1-Responsive microRNA-15b Negatively Regulates Rhabdovirus-Triggered Innate Immune Responses in Lower Vertebrates by Targeting TBK1

Frontiers in Immunology ◽

10.3389/fimmu.2020.625828 ◽

2021 ◽

Vol 11 ◽

Author(s):

Renjie Chang ◽

Qing Chu ◽

Weiwei Zheng ◽

Lei Zhang ◽

Tianjun Xu

Keyword(s):

Immune Response ◽

Immune Responses ◽

Innate Immune ◽

Infection Model ◽

Regulation Mechanism ◽

Type I ◽

Innate Immune Responses ◽

Positive Role ◽

Siniperca Chuatsi ◽

Antiviral Immune Response

As is known to all, the production of type I interferon (IFN) plays pivotal roles in host innate antiviral immunity, and its moderate production play a positive role in promoting the activation of host innate antiviral immune response. However, the virus will establish a persistent infection model by interfering with the production of IFN, thereby evading the organism inherent antiviral immune response. Therefore, it is of great necessity to research the underlying regulatory mechanisms of type I IFN appropriate production under viral invasion. In this study, we report that a Sp1–responsive miR-15b plays a negative role in siniperca chuatsi rhabdovirus (SCRV)-triggered antiviral response in teleost fish. We found that SCRV could dramatically upregulate miiuy croaker miR-15b expression. Enhanced miR-15b could negatively regulate SCRV-triggered antiviral genes and inflammatory cytokines production by targeting TANK-binding kinase 1 (TBK1), thereby accelerating viral replication. Importantly, we found that miR-15b feedback regulates antiviral innate immune response through NF-κB and IRF3 signaling pathways. These findings highlight that miR-15b plays a crucial role in regulating virus–host interactions, which outlines a new regulation mechanism of fish’s innate immune responses.

Download Full-text

Herpes Simplex Virus 1 Infection of Neuronal and Non-Neuronal Cells Elicits Specific Innate Immune Responses and Immune Evasion Mechanisms

Frontiers in Immunology ◽

10.3389/fimmu.2021.644664 ◽

2021 ◽

Vol 12 ◽

Author(s):

Amanda L. Verzosa ◽

Lea A. McGeever ◽

Shun-Je Bhark ◽

Tracie Delgado ◽

Nicole Salazar ◽

...

Keyword(s):

Herpes Simplex ◽

Epithelial Cells ◽

Immune Responses ◽

Host Cell ◽

Signaling Pathways ◽

Sensory Neurons ◽

Immune Evasion ◽

Innate Immune ◽

Innate Immune Responses ◽

Hsv 1

Alphaherpesviruses (α-HV) are a large family of double-stranded DNA viruses which cause many human and animal diseases. There are three human α-HVs: Herpes Simplex Viruses (HSV-1 and HSV-2) and Varicella Zoster Virus (VZV). All α-HV have evolved multiple strategies to suppress or exploit host cell innate immune signaling pathways to aid in their infections. All α-HVs initially infect epithelial cells (primary site of infection), and later spread to infect innervating sensory neurons. As with all herpesviruses, α-HVs have both a lytic (productive) and latent (dormant) stage of infection. During the lytic stage, the virus rapidly replicates in epithelial cells before it is cleared by the immune system. In contrast, latent infection in host neurons is a life-long infection. Upon infection of mucosal epithelial cells, herpesviruses immediately employ a variety of cellular mechanisms to evade host detection during active replication. Next, infectious viral progeny bud from infected cells and fuse to neuronal axonal terminals. Here, the nucleocapsid is transported via sensory neuron axons to the ganglion cell body, where latency is established until viral reactivation. This review will primarily focus on how HSV-1 induces various innate immune responses, including host cell recognition of viral constituents by pattern-recognition receptors (PRRs), induction of IFN-mediated immune responses involving toll-like receptor (TLR) signaling pathways, and cyclic GMP‐AMP synthase stimulator of interferon genes (cGAS-STING). This review focuses on these pathways along with other mechanisms including autophagy and the complement system. We will summarize and discuss recent evidence which has revealed how HSV-1 is able to manipulate and evade host antiviral innate immune responses both in neuronal (sensory neurons of the trigeminal ganglia) and non-neuronal (epithelial) cells. Understanding the innate immune response mechanisms triggered by HSV-1 infection, and the mechanisms of innate immune evasion, will impact the development of future therapeutic treatments.

Download Full-text

Novel Functions of IFI44L as a Feedback Regulator of Host Antiviral Responses

Journal of Virology ◽

10.1128/jvi.01159-19 ◽

2019 ◽

Vol 93 (21) ◽

Cited By ~ 9

Author(s):

Marta L. DeDiego ◽

Luis Martinez-Sobrido ◽

David J. Topham

Keyword(s):

Immune Responses ◽

Nuclear Factor Kappa B ◽

Virus Production ◽

Innate Immune ◽

Type I ◽

Nuclear Factor ◽

Innate Immune Responses ◽

Virus Infections ◽

Nuclear Factor Kappa ◽

Ifn Treatment

ABSTRACT We describe a novel function for the interferon (IFN)-induced protein 44-like (IFI44L) gene in negatively modulating innate immune responses induced after virus infections. Furthermore, we show that decreasing IFI44L expression impairs virus production and that IFI44L expression negatively modulates the antiviral state induced by an analog of double-stranded RNA (dsRNA) or by IFN treatment. The mechanism likely involves the interaction of IFI44L with cellular FK506-binding protein 5 (FKBP5), which in turn interacts with kinases essential for type I and III IFN responses, such as inhibitor of nuclear factor kappa B (IκB) kinase alpha (IKKα), IKKβ, and IKKε. Consequently, binding of IFI44L to FKBP5 decreased interferon regulatory factor 3 (IRF-3)-mediated and nuclear factor kappa-B (NF-κB) inhibitor (IκBα)-mediated phosphorylation by IKKε and IKKβ, respectively. According to these results, IFI44L is a good target for treatment of diseases associated with excessive IFN levels and/or proinflammatory responses and for reduction of viral replication. IMPORTANCE Excessive innate immune responses can be deleterious for the host, and therefore, negative feedback is needed. Here, we describe a completely novel function for IFI44L in negatively modulating innate immune responses induced after virus infections. In addition, we show that decreasing IFI44L expression impairs virus production and that IFI44L expression negatively modulates the antiviral state induced by an analog of dsRNA or by IFN treatment. IFI44L binds to the cellular protein FKBP5, which in turn interacts with kinases essential for type I and III IFN induction and signaling, such as the kinases IKKα, IKKβ, and IKKε. IFI44L binding to FKBP5 decreased the phosphorylation of IRF-3 and IκBα mediated by IKKε and IKKβ, respectively, providing an explanation for the function of IFI44L in negatively modulating IFN responses. Therefore, IFI44L is a candidate target for reducing virus replication.

Download Full-text