scholarly journals Inducible Guanylate-Binding Protein 7 Facilitates Influenza A Virus Replication by Suppressing Innate Immunity via NF-κB and JAK-STAT Signaling Pathways

2021 ◽  
Author(s):  
Mingkai Feng ◽  
Qiao Zhang ◽  
Wenjiao Wu ◽  
Lizhu Chen ◽  
Shuyin Gu ◽  
...  
Keyword(s):  
Immune Responses ◽  
Signaling Pathways ◽  
Influenza A ◽  
Binding Protein ◽  
A549 Cells ◽  
Innate Immune ◽  
Type I ◽  
Innate Immune Responses ◽  
Stat Signaling ◽  
Guanylate Binding Protein

Guanylate-binding protein 7 (GBP7) belongs to the GBP family, which plays key roles in mediating innate immune responses to intracellular pathogens. Thus far, GBP7 has been reported to be a critical cellular factor against bacterial infection. However, the relationship between GBP7 and influenza A virus (IAV) replication is unknown. Here, we showed that GBP7 expression was significantly up-regulated in the lungs of mice, human peripheral blood mononuclear cells (PBMCs), and A549 cells during IAV infection. Using the CRISPR-Cas9 system and overexpression approaches, it was found that GBP7 knockout inhibited IAV replication by enhancing the expression of IAV-induced type I interferon (IFN), type III IFN, and proinflammatory cytokines. Conversely, overexpression of GBP7 facilitated IAV replication by suppressing the expression of those factors. Furthermore, GBP7 knockout enhanced IAV-induced nuclear factor-κB (NF-κB) activation and phosphorylation of stat1 and stat2, overexpression of GBP7 had the opposite effect. Our data indicated that GBP7 suppresses innate immune responses to IAV infection via NF-κB and JAK-STAT signaling pathways. Taken together, upon IAV infection, the induced GBP7 facilitated IAV replication by suppressing innate immune responses to IAV infection, which suggested that GBP7 might serve as a potential therapeutic target for controlling IAV infection. IMPORTANCE So far, few studies have mentioned the distinct function of guanylate-binding protein 7 (GBP7) on virus infection. Here, we reported that GBP7 expression was significantly up-regulated in the lungs of mice, human PBMCs, and A549 cells during IAV infection. GBP7 facilitated IAV replication by suppressing the expression of type I interferon (IFN), type III IFN, and proinflammatory cytokines. Furthermore, it was indicated that GBP7 suppresses innate immune responses to IAV infection via NF-κB and JAK-STAT signaling pathways. Taken together, our results elucidate a critical role of GBP7 in host immune system during IAV infection.

scholarly journals Human Hemoglobin Subunit Beta Functions as a Pleiotropic Regulator of RIG-I/MDA5-Mediated Antiviral Innate Immune Responses

2019 ◽  
Vol 93 (16) ◽  
Author(s):  
Qian Yang ◽  
Si-Yu Bai ◽  
Lian-Feng Li ◽  
Su Li ◽  
Yuexiu Zhang ◽  
...  
Keyword(s):  
Immune Responses ◽  
Signaling Pathways ◽  
Redox State ◽  
Innate Immune ◽  
Type I ◽  
Innate Immune Responses ◽  
Antiviral Signaling ◽  
Antiviral Responses ◽  
Antiviral Innate Immunity ◽  
Pleiotropic Regulator

ABSTRACT Hemoglobin is an important oxygen-carrying protein and plays crucial roles in establishing host resistance against pathogens and in regulating innate immune responses. The hemoglobin subunit beta (HB) is an essential component of hemoglobin, and we have previously demonstrated that the antiviral role of the porcine HB (pHB) is mediated by promoting type I interferon pathways. Thus, considering the high homology between human HB (hHB) and pHB, we hypothesized that hHB also plays an important role in the antiviral innate immunity. In this study, we characterized hHB as a regulatory factor for the replication of RNA viruses by differentially regulating the RIG-I- and MDA5-mediated antiviral signaling pathways. Furthermore, we showed that hHB directly inhibited MDA5-mediated signaling by reducing the MDA5–double-stranded RNA (dsRNA) interaction. Additionally, hHB required hHB-induced reactive oxygen species (ROS) to promote RIG-I-mediated signaling through enhancement of K63-linked RIG-I ubiquitination. Taken together, our findings suggest that hHB is a pleiotropic regulator of RIG-I/MDA5-mediated antiviral responses and further highlight the importance of the intercellular microenvironment, including the redox state, in regulating antiviral innate immune responses. IMPORTANCE Hemoglobin, the most important oxygen-carrying protein, is involved in the regulation of innate immune responses. We have previously reported that the porcine hemoglobin subunit beta (HB) exerts antiviral activity through regulation of type I interferon production. However, the antiviral activities and the underlying mechanisms of HBs originating from other animals have been poorly understood. Here, we identified human HB (hHB) as a pleiotropic regulator of the replication of RNA viruses through regulation of RIG-I/MDA5-mediated signaling pathways. hHB enhances RIG-I-mediated antiviral responses by promoting RIG-I ubiquitination depending on the hHB-induced reactive oxygen species (ROS), while it blocks MDA5-mediated antiviral signaling by suppressing the MDA5-dsRNA interaction. Our results contribute to an understanding of the crucial roles of hHB in the regulation of the RIG-I/MDA5-mediated signaling pathways. We also provide novel insight into the correlation of the intercellular redox state with the regulation of antiviral innate immunity.

scholarly journals Current Views of Toll-Like Receptor Signaling Pathways

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Masahiro Yamamoto ◽  
Kiyoshi Takeda
Keyword(s):  
Immune Responses ◽  
Signaling Pathways ◽  
Innate Immune ◽  
Acquired Immunity ◽  
Type I ◽  
Innate Immune Responses ◽  
Toll Like Receptor ◽  
Microbial Invasion ◽  
Tir Domains ◽  
The Relationship

On microbial invasion, the host immediately evokes innate immune responses. Recent studies have demonstrated that Toll-like receptors (TLRs) play crucial roles in innate responses that lead not only to the clearance of pathogens but also to the efficient establishment of acquired immunity by directly detecting molecules from microbes. In terms of intracellular TLR-mediated signaling pathways, cytoplasmic adaptor molecules containing Toll/IL-1R (TIR) domains play important roles in inflammatory immune responses through the production of proinflammatory cytokines, nitric oxide, and type I interferon, and upregulation of costimulatory molecules. In this paper, we will describe our current understanding of the relationship between TLRs and their ligands derived from pathogens such as viruses, bacteria, fungi, and parasites. Moreover, we will review the historical and current literature to describe the mechanisms behind TLR-mediated activation of innate immune responses.

scholarly journals Lipopolysaccharide activates innate immune responses in murine intestinal myofibroblasts through multiple signaling pathways

2009 ◽  
Vol 296 (3) ◽  
pp. G601-G611 ◽  
Author(s):  
Kristen L. W. Walton ◽  
Lisa Holt ◽  
R. Balfour Sartor
Keyword(s):  
Immune Responses ◽  
Signaling Pathways ◽  
P38 Mapk ◽  
Western Blotting ◽  
Pi3 Kinase ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Fold Induction ◽  
Cox 2 ◽  
Multiple Signaling

Myofibroblasts (MF) play an important role in intestinal wound healing. A compromised epithelial barrier exposes intestinal subepithelial MF to luminal bacterial products. However, responses of murine intestinal MF to bacterial adjuvants and potential roles of intestinal MF in innate immune responses are not well defined. Our aims in this study were to determine innate immune responses and intracellular signaling pathways of intestinal MF exposed to LPS, a prototypic Toll-like receptor (TLR) ligand. Expression of TLR4 in primary murine intestinal MF cultures was confirmed by RT-PCR and Western blotting. LPS-induced secretion of prostaglandin E2 (PGE2), interleukin (IL)-6, and keratinocyte-derived chemokines (KC) was measured by ELISA. Intracellular responses to LPS were assessed by Western blotting for NF-κB p65, Iκ-Bα, Akt, p38 MAP kinase, and cyclooxygenase-2 (COX-2). LPS induced rapid phosphorylation of NF-κB p65, Akt, and p38 MAPK and degradation of Iκ-Bα. LPS induced expression of COX-2 and secretion of PGE2 (2.0 ± 0.8-fold induction vs. unstimulated cells), IL-6 (6.6 ± 0.4-fold induction), and KC (12.5 ± 0.4-fold induction). Inhibition of phosphoinositide-3 (PI3)-kinase, p38 MAPK, or NF-κB pathways reduced LPS-induced PGE2, IL-6, and KC secretion. These studies show that primary murine intestinal MF respond to LPS, evidenced by activation of NF-κB, PI3-kinase, and MAPK signaling pathways and secretion of proinflammatory molecules. Inhibition of these pathways attenuated LPS-dependent PGE2, IL-6, and KC production, indicating that LPS activates MF by multiple signaling pathways. These data support the hypothesis that MF are a component of the innate immune system and may exert paracrine effects on adjacent epithelial and immune cells by responding to luminal bacterial adjuvants.

scholarly journals Modulation of Innate Immune Responses by the Influenza A NS1 and PA-X Proteins

Viruses ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 708 ◽  
Author(s):  
Aitor Nogales ◽  
Luis Martinez-Sobrido ◽  
David Topham ◽  
Marta DeDiego
Keyword(s):  
Immune Responses ◽  
Influenza A ◽  
Defense Mechanisms ◽  
Synergistic Effects ◽  
Viral Proteins ◽  
Economic Problem ◽  
Innate Immune ◽  
Host Protein ◽  
Innate Immune Responses ◽  
Influenza A Viruses

Influenza A viruses (IAV) can infect a broad range of animal hosts, including humans. In humans, IAV causes seasonal annual epidemics and occasional pandemics, representing a serious public health and economic problem, which is most effectively prevented through vaccination. The defense mechanisms that the host innate immune system provides restrict IAV replication and infection. Consequently, to successfully replicate in interferon (IFN)-competent systems, IAV has to counteract host antiviral activities, mainly the production of IFN and the activities of IFN-induced host proteins that inhibit virus replication. The IAV multifunctional proteins PA-X and NS1 are virulence factors that modulate the innate immune response and virus pathogenicity. Notably, these two viral proteins have synergistic effects in the inhibition of host protein synthesis in infected cells, although using different mechanisms of action. Moreover, the control of innate immune responses by the IAV NS1 and PA-X proteins is subject to a balance that can determine virus pathogenesis and fitness, and recent evidence shows co-evolution of these proteins in seasonal viruses, indicating that they should be monitored for enhanced virulence. Importantly, inhibition of host gene expression by the influenza NS1 and/or PA-X proteins could be explored to develop improved live-attenuated influenza vaccines (LAIV) by modulating the ability of the virus to counteract antiviral host responses. Likewise, both viral proteins represent a reasonable target for the development of new antivirals for the control of IAV infections. In this review, we summarize the role of IAV NS1 and PA-X in controlling the antiviral response during viral infection.

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

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.

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

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.

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

2019 ◽  
Vol 93 (21) ◽  
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.

scholarly journals Immunologic Consequences of Hypoxia during Critical Illness

2016 ◽  
Vol 125 (1) ◽  
pp. 237-249 ◽  
Author(s):  
Harmke D. Kiers ◽  
Gert-Jan Scheffer ◽  
Johannes G. van der Hoeven ◽  
Holger K. Eltzschig ◽  
Peter Pickkers ◽  
...  
Keyword(s):  
Immune Responses ◽  
Signaling Pathways ◽  
Daily Practice ◽  
Innate Immune ◽  
Protective Effects ◽  
Innate Immune Responses ◽  
Downstream Signaling ◽  
Pathogen Clearance ◽  
Pharmacologic Modulation ◽  
Oxygen Status

Abstract Hypoxia and immunity are highly intertwined at clinical, cellular, and molecular levels. The prevention of tissue hypoxia and modulation of systemic inflammation are cornerstones of daily practice in the intensive care unit. Potentially, immunologic effects of hypoxia may contribute to outcome and represent possible therapeutic targets. Hypoxia and activation of downstream signaling pathways result in enhanced innate immune responses, aimed to augment pathogen clearance. On the other hand, hypoxia also exerts antiinflammatory and tissue-protective effects in lymphocytes and other tissues. Although human data on the net immunologic effects of hypoxia and pharmacologic modulation of downstream pathways are limited, preclinical data support the concept of tailoring the immune response through modulation of the oxygen status or pharmacologic modulation of hypoxia-signaling pathways in critically ill patients.

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