ASFV pD345L protein negatively regulates NF-kB signaling through inhibiting IKK kinase activity

The NF-κB pathway is an essential signaling process against viral infection including African swine fever virus (ASFV). ASFV encodes for more than 151 proteins by its own transcription machinery and possesses a great capacity to evade or subvert antiviral innate immune responses. A couple of such viral proteins have been reported, but many remain unknown. Here, we showed that pD345L, an ASFV-encoded lambda-like exonuclease, is an inhibitor of cGAS/STING mediated NF-κB sig-naling by blocking IKKα/β kinase activity. Specifically, we showed that overexpression of pD345L suppresses cGAS/STING induced IFNβ and NF-κB activation, resulting in decreased transcription of IFNβ and several pro-inflammatory cytokines, including IL-1α, IL-6, IL-8, and TNFα. In addition, we showed that pD345L targeted at or downstream of IKK and upstream of p65. Importantly, we found that pD345L associates with KD and HLH domains of IKKα and LZ domain of IKKβ, and thus interrupts their kinase activity on downstream substrate IκBα. Finally, we showed that pD345L inhibition of NF-κB signaling was independent of its exonuclease activity. Taken together, we concluded that pD345L blocks IKKα/β kinase activity by protein-protein interaction and thus disrupts cGAS/STING mediated NF-κB signaling.

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pMGF505-7R determines pathogenicity of African swine fever virus infection by inhibiting IL-1β and type I IFN production

PLoS Pathogens ◽

10.1371/journal.ppat.1009733 ◽

2021 ◽

Vol 17 (7) ◽

pp. e1009733

Author(s):

Jiangnan Li ◽

Jie Song ◽

Li Kang ◽

Li Huang ◽

Shijun Zhou ◽

...

Keyword(s):

Immune Responses ◽

Inflammatory Responses ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Innate Immune ◽

Fever Virus ◽

Type I ◽

Type I Ifn ◽

Innate Immune Responses

Inflammatory factors and type I interferons (IFNs) are key components of host antiviral innate immune responses, which can be released from the pathogen-infected macrophages. African swine fever virus (ASFV) has developed various strategies to evade host antiviral innate immune responses, including alteration of inflammatory responses and IFNs production. However, the molecular mechanism underlying inhibition of inflammatory responses and IFNs production by ASFV-encoded proteins has not been fully understood. Here we report that ASFV infection only induced low levels of IL-1β and type I IFNs in porcine alveolar macrophages (PAMs), even in the presence of strong inducers such as LPS and poly(dA:dT). Through further exploration, we found that several members of the multigene family 360 (MGF360) and MGF505 strongly inhibited IL-1β maturation and IFN-β promoter activation. Among them, pMGF505-7R had the strongest inhibitory effect. To verify the function of pMGF505-7R in vivo, a recombinant ASFV with deletion of the MGF505-7R gene (ASFV-Δ7R) was constructed and assessed. As we expected, ASFV-Δ7R infection induced higher levels of IL-1β and IFN-β compared with its parental ASFV HLJ/18 strain. ASFV infection-induced IL-1β production was then found to be dependent on TLRs/NF-κB signaling pathway and NLRP3 inflammasome. Furthermore, we demonstrated that pMGF505-7R interacted with IKKα in the IKK complex to inhibit NF-κB activation and bound to NLRP3 to inhibit inflammasome formation, leading to decreased IL-1β production. Moreover, we found that pMGF505-7R interacted with and inhibited the nuclear translocation of IRF3 to block type I IFN production. Importantly, the virulence of ASFV-Δ7R is reduced in piglets compared with its parental ASFV HLJ/18 strain, which may due to induction of higher IL-1β and type I IFN production in vivo. Our findings provide a new clue to understand the functions of ASFV-encoded pMGF505-7R and its role in viral infection-induced pathogenesis, which might help design antiviral agents or live attenuated vaccines to control ASF.

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African swine fever virus regulates host energy and amino acid metabolism to promote viral replication

Journal of Virology ◽

10.1128/jvi.01919-21 ◽

2021 ◽

Author(s):

Qiao Xue ◽

Huisheng Liu ◽

Zixiang Zhu ◽

Fan Yang ◽

Yingying Song ◽

...

Keyword(s):

Amino Acids ◽

Immune Responses ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Tca Cycle ◽

Innate Immune ◽

Fever Virus ◽

Innate Immune Responses ◽

First Time ◽

Self Replication

African swine fever is one of the most serious viral diseases caused by African swine fever virus (ASFV). The metabolic changes induced by ASFV infection remain unknown. Here, PAMs infected with ASFV was analyzed by ultra-high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS) in combination with multivariate statistical analysis. A total of 90 metabolites were significantly changed after ASFV infection, and most of them belong to amino acids and TCA cycle intermediates. ASFV infection induced increase of most of amino acids in host during the early stages of infection, and amino acids decreased in the late stages of infection. ASFV infection did not significantly affected glycolysis pathway, whereas it induced the increase of citrate, succinate, α-ketoglutarate, and oxaloacetate levels in the TCA cycle, suggesting that ASFV infection promoted TCA cycle. The activity of aspartate aminotransferase and glutamate production were significantly elevated in ASFV-infected cells and pigs, resulting in reversible transition between TCA cycle and amino acids synthesis. Aspartate, glutamate, and TCA cycle were essential for ASFV replication. In addition, ASFV infection induced an increase in lactate level using lactate dehydrogenase, which led to low expression of IFN-β and increased of ASFV replication. Our data, for the first time, indicated that ASFV infection controls IFN-β production through RIG-I-mediated signaling pathways. These data identified a novel mechanism evolved by ASFV to inhibit host innate immune responses, and will provide insights for development of new preventive or therapeutic strategies targeting the altered metabolic pathways. IMPORTANCE In order to promote viral replication, viruses often cause severe immunosuppression and seize organelles to synthesize a large number of metabolites required for self-replication. African swine fever virus (ASFV) has developed many strategies to evade host innate immune responses. However, the impact of ASFV infection on host cellular metabolism remains unknown. Here, for the first time, we analyzed the metabolomic profiles of ASFV-infected PAMs cells. ASFV infection increased host TCA cycle and amino acids metabolism. Aspartate, glutamate, and TCA cycle promoted ASFV replication. ASFV infection also induced the increase of lactate production to inhibit innate immune responses for self-replication. This study identified novel immune evasion mechanisms utilized by ASFV and provided viewpoints on ASFV-host interactions, which is critical for guiding the design of new prevention strategies against ASFV targeting the altered metabolic pathways.

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The African swine fever virus protease pS273R inhibits DNA sensing cGAS-STING pathway by targeting IKKε

10.1101/2021.06.02.446855 ◽

2021 ◽

Author(s):

Jia Luo ◽

Jinghua Ni ◽

Sen Jiang ◽

Nengwen Xia ◽

Yiwen Guo ◽

...

Keyword(s):

Immune Responses ◽

Immune Escape ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Innate Immune ◽

Fever Virus ◽

Negative Regulator ◽

Type I ◽

Innate Immune Responses ◽

Sting Pathway

African swine fever virus (ASFV), a large and complex cytoplasmic double-stranded DNA virus, has developed multiple strategies to evade the antiviral innate immune responses. Cytosolic DNA arising from invading ASFV is mainly detected by the cyclic GMP-AMP synthase (cGAS) and then triggers a series of innate immune responses to prevent virus invasion. However, the immune escape mechanism of ASFV remains to be fully clarified. The pS273R of ASFV is a member of the SUMO-1-specific protease family and is crucial for valid virus replication. In this study, we identified pS273R as a suppressor of cGAS-STING pathway mediated type I interferon (IFN) production by ASFV genomic open reading frame screening. The pS273R was further confirmed as an inhibitor of IFN production as well as its downstream antiviral genes in cGAS-STING pathway. Mechanistically, pS273R greatly decreased the cGAS-STING signaling by targeting IKKe but not TBK1 and pS273R was found to disturb the interaction between IKKe and STING through its interaction with IKKe. Further, mutational analyses revealed that pS273R antagonized the cGAS-STING pathway by enzyme catalytic activity, which may affect the IKKe sumoylation state required for the interaction with STING. In summary, our results revealed for the first time that pS273R acts as an obvious negative regulator of cGAS-STING pathway by targeting IKKϵ via its enzymatic activity, which shows a new immune evasion mechanism of ASFV.

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Synergism between TLRs and NOD1/2 in Oral Epithelial Cells

Journal of Dental Research ◽

10.1177/154405910808700709 ◽

2008 ◽

Vol 87 (7) ◽

pp. 682-686 ◽

Cited By ~ 27

Author(s):

A. Uehara ◽

H. Takada

Keyword(s):

Epithelial Cells ◽

Immune Responses ◽

Inflammatory Cytokines ◽

Oral Bacteria ◽

Innate Immune ◽

Oral Epithelium ◽

Innate Immune Responses ◽

Oral Epithelial Cells ◽

Oral Epithelial ◽

Pro Inflammatory Cytokines

Oral epithelium is the first barrier against oral bacteria in periodontal tissue. Oral epithelial cells constitutively express Toll-like receptors (TLRs) and NOD1/2, functional receptors which induce the production of antibacterial factors such as peptidoglycan recognition proteins (PGRPs) and β-defensin 2, but not pro-inflammatory cytokines such as interleukin (IL)-8. In this study, we hypothesized that innate immune responses in the oral epithelium are enhanced in inflamed tissue. We found that NOD1 and NOD2 agonists, in combination with TLR agonists, synergistically induced production of PGRPs and of β-defensin 2 in human oral epithelial cells via NF-κB. In contrast, co-stimulation with NOD1/2 and TLR ligands had no effect on the production of pro-inflammatory cytokines (IL-6, IL-8, and monocyte chemoattractant protein-1). These findings indicate that, in innate immune responses to invading microbes, a combination of signaling through TLRs and NODs leads to the synergistic activation of antibacterial responses in the oral epithelium.

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STING recruits NLRP3 to the ER and deubiquitinates NLRP3 to activate the inflammasome

10.1101/681338 ◽

2019 ◽

Author(s):

Wenbiao Wang ◽

Dingwen Hu ◽

Yuqian Feng ◽

Caifeng Wu ◽

Aixin Li ◽

...

Keyword(s):

Immune Responses ◽

Nlrp3 Inflammasome ◽

Inflammatory Responses ◽

Innate Immune ◽

Inflammasome Activation ◽

Primary Cells ◽

Innate Immune Responses ◽

Distinct Mechanism ◽

Nlrp3 Inflammasome Activation ◽

Pro Inflammatory Cytokines

AbstractOne of the fundamental reactions of the innate immune responses to pathogen infection is the release of pro-inflammatory cytokines, including IL-1β, processed by the NLRP3 inflammasome. STING is essential for innate immune responses and inflammasome activation. Here we reveal a distinct mechanism by which STING regulates the NLRP3 inflammasome activation, IL-1β secretion, and inflammatory responses in human cell lines, mice primary cells, and mice. Interestingly, upon HSV-1 infection and cytosolic DNA stimulation, STING binds to NLRP3 and promotes the inflammasome activation through two approaches. First, STING recruits NLRP3 and promotes NLRP3 translocation to the endoplasmic reticulum, thereby facilitating the inflammasome formation. Second, STING interacts with NLRP3 and removes K48- and K63-linked polyubiquitination of NLRP3, thereby promoting the inflammasome activation. Collectively, we demonstrate that the cGAS-STING-NLRP3 signaling is essential for host defense against DNA virus infection.

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The effective regulation of pro- and anti-inflammatory cytokines induced by combination of PA-MSHA and BPIFB1 in initiation of innate immune responses

Open Medicine ◽

10.1515/med-2017-0044 ◽

2017 ◽

Vol 12 (1) ◽

pp. 299-307 ◽

Cited By ~ 1

Author(s):

Weiqiang Zhou ◽

Zhiwen Duan ◽

Biao Yang ◽

Chunling Xiao

Keyword(s):

Inflammatory Response ◽

Immune Responses ◽

Inflammatory Cytokines ◽

Late Phase ◽

Upper Airway ◽

Innate Immune ◽

Antibody Array ◽

Innate Immune Responses ◽

Anti Inflammatory ◽

Pro Inflammatory Cytokines

AbstractPA-MSHA and BPIFB1 play especially important roles in triggering innate immune responses by inducing production of pro- or anti-inflammatory cytokines in the oral cavity and upper airway. We found that PA-MSHA had a strong ability to activate pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. However, BPIFB1 alone did not express a directly inductive effect. With incubation of PA-MSHA and BPIFB1, the combination can activate the CD14/TLR4/MyD88 complex and induce secretion of subsequent downstream cytokines. We used a proteome profiler antibody array to evaluate the phosphokinases status with PA-MSHA and BPIFB1 treatment. The results showed that the activation of MAPK, STAT, and PI-3K pathways is involved in PA-MSHA-BPIFB1 treatment, and that the related pathways control the secretion of targeting cytokines in the downstream. When we assessed the content changes of cytokines, we found that PA-MSHA-BPIFB1 treatment increased the production of pro-inflammatory cytokines in the early phase of treatment and induced the increase of IL-4 in the late phase. Our observations suggest that PA-MSHA-BPIFB1 stimulates the release of pro-inflammatory cytokines, and thereby initiates the innate immune system against inflammation. Meanwhile, the gradual release of anti-inflammatory cytokine IL-4 by PA-MSHA-BPIFB1 can also regulate the degree of inflammatory response; thus the host can effectively resist the environmental risks, but also manipulate inflammatory response in an appropriate and adjustable manner.

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Oral Immune Activation by Disgust and Disease-Related Pictures

Journal of Psychophysiology ◽

10.1027/0269-8803/a000143 ◽

2015 ◽

Vol 29 (3) ◽

pp. 119-129 ◽

Cited By ~ 4

Author(s):

Richard J. Stevenson ◽

Deborah Hodgson ◽

Megan J. Oaten ◽

Luba Sominsky ◽

Mehmet Mahmut ◽

...

Keyword(s):

Immune Response ◽

Immune Responses ◽

Innate Immune Response ◽

Negative Control ◽

Innate Immune ◽

Innate Immune Responses ◽

Immune Markers ◽

Before And After ◽

Secondary Analyses ◽

Image Set

Abstract. Both disgust and disease-related images appear able to induce an innate immune response but it is unclear whether these effects are independent or rely upon a common shared factor (e.g., disgust or disease-related cognitions). In this study we directly compared these two inductions using specifically generated sets of images. One set was disease-related but evoked little disgust, while the other set was disgust evoking but with less disease-relatedness. These two image sets were then compared to a third set, a negative control condition. Using a wholly within-subject design, participants viewed one image set per week, and provided saliva samples, before and after each viewing occasion, which were later analyzed for innate immune markers. We found that both the disease related and disgust images, relative to the negative control images, were not able to generate an innate immune response. However, secondary analyses revealed innate immune responses in participants with greater propensity to feel disgust following exposure to disease-related and disgusting images. These findings suggest that disgust images relatively free of disease-related themes, and disease-related images relatively free of disgust may be suboptimal cues for generating an innate immune response. Not only may this explain why disgust propensity mediates these effects, it may also imply a common pathway.

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