scholarly journals The uric acid crystal receptor Clec12A potentiates type I interferon responses

2019 ◽  
Vol 116 (37) ◽  
pp. 18544-18549 ◽  
Author(s):  
Kai Li ◽  
Konstantin Neumann ◽  
Vikas Duhan ◽  
Sukumar Namineni ◽  
Anne Louise Hansen ◽  
...  
Keyword(s):  
Uric Acid ◽  
Myeloid Cell ◽  
Lymphocytic Choriomeningitis ◽  
Host Cells ◽  
Type I ◽  
Lectin Receptor ◽  
Molecular Patterns ◽  
Interferon Responses

The detection of microbes and damaged host cells by the innate immune system is essential for host defense against infection and tissue homeostasis. However, how distinct positive and negative regulatory signals from immune receptors are integrated to tailor specific responses in complex scenarios remains largely undefined. Clec12A is a myeloid cell-expressed inhibitory C-type lectin receptor that can sense cell death under sterile conditions. Clec12A detects uric acid crystals and limits proinflammatory pathways by counteracting the cell-activating spleen tyrosine kinase (Syk). Here, we surprisingly find that Clec12A additionally amplifies type I IFN (IFN-I) responses in vivo and in vitro. Using retinoic acid-inducible gene I (RIG-I) signaling as a model, we demonstrate that monosodium urate (MSU) crystal sensing by Clec12A enhances cytosolic RNA-induced IFN-I production and the subsequent induction of IFN-I–stimulated genes. Mechanistically, Clec12A engages Src kinase to positively regulate the TBK1-IRF3 signaling module. Consistently, Clec12A-deficient mice exhibit reduced IFN-I responses upon lymphocytic choriomeningitis virus (LCMV) infection, which affects the outcomes of these animals in acute and chronic virus infection models. Thus, our results uncover a previously unrecognized connection between an MSU crystal-sensing receptor and the IFN-I response, and they illustrate how the sensing of extracellular damage-associated molecular patterns (DAMPs) can shape the immune response.

scholarly journals Slow viral propagation during initial phase of infection leads to viral persistence in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Haifeng C. Xu ◽  
Ruifeng Wang ◽  
Prashant V. Shinde ◽  
Lara Walotka ◽  
Anfei Huang ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Evasion ◽  
Protein Transport ◽  
Adaptive Immune System ◽  
Viral Persistence ◽  
Lymphocytic Choriomeningitis ◽  
Type I ◽  
Viral Propagation

AbstractImmune evasion of pathogens can modify the course of infection and impact viral persistence and pathology. Here, using different strains of the lymphocytic choriomeningitis virus (LCMV) model system, we show that slower propagation results in limited type I interferon (IFN-I) production and viral persistence. Specifically, cells infected with LCMV-Docile exhibited reduced viral replication when compared to LCMV-WE and as a consequence, infection with LCMV-Docile resulted in reduced activation of bone marrow derived dendritic cells (BMDCs) and IFN-I production in vitro in comparison with LCMV-WE. In vivo, we observed a reduction of IFN-I, T cell exhaustion and viral persistence following infection of LCMV-Docile but not LCMV-WE. Mechanistically, block of intracellular protein transport uncovered reduced propagation of LCMV-Docile when compared to LCMV-WE. This reduced propagation was critical in blunting the activation of the innate and adaptive immune system. When mice were simultaneously infected with LCMV-Docile and LCMV-WE, immune function was restored and IFN-I production, T cell effector functions as well as viral loads were similar to that of mice infected with LCMV-WE alone. Taken together, this study suggests that reduced viral propagation can result in immune evasion and viral persistence.

scholarly journals ROP18-Mediated Transcriptional Reprogramming of HEK293T Cell Reveals New Roles of ROP18 in the Interplay Between Toxoplasma gondii and the Host Cell

2020 ◽  
Vol 10 ◽  
Author(s):  
Jie-Xi Li ◽  
Jun-Jun He ◽  
Hany M. Elsheikha ◽  
Jun Ma ◽  
Xiao-Pei Xu ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Hek293t Cell ◽  
Effector Proteins ◽  
Host Cells ◽  
Pathway Enrichment Analysis ◽  
Type I ◽  
Human Embryonic Kidney Cells ◽  
Pathway Enrichment

Toxoplasma gondii secretes a number of virulence-related effector proteins, such as the rhoptry protein 18 (ROP18). To further broaden our understanding of the molecular functions of ROP18, we examined the transcriptional response of human embryonic kidney cells (HEK293T) to ROP18 of type I T. gondii RH strain. Using RNA-sequencing, we compared the transcriptome of ROP18-expressing HEK293T cells to control HEK293T cells. Our analysis revealed that ROP18 altered the expression of 750 genes (467 upregulated genes and 283 downregulated genes) in HEK293T cells. Gene ontology (GO) and pathway enrichment analyses showed that differentially expressed genes (DEGs) were significantly enriched in extracellular matrix– and immune–related GO terms and pathways. KEGG pathway enrichment analysis revealed that DEGs were involved in several disease-related pathways, such as nervous system diseases and eye disease. ROP18 significantly increased the alternative splicing pattern “retained intron” and altered the expression of 144 transcription factors (TFs). These results provide new insight into how ROP18 may influence biological processes in the host cells via altering the expression of genes, TFs, and pathways. More in vitro and in vivo studies are required to substantiate these findings.

scholarly journals Type I and Type II Interferons Inhibit the Translation of Murine Norovirus Proteins

2009 ◽  
Vol 83 (11) ◽  
pp. 5683-5692 ◽  
Author(s):  
Harish Changotra ◽  
Yali Jia ◽  
Tara N. Moore ◽  
Guangliang Liu ◽  
Shannon M. Kahan ◽  
...  
Keyword(s):  
Viral Replication ◽  
Small Animal ◽  
Type I ◽  
Type Ii ◽  
Murine Norovirus ◽  
Human Noroviruses ◽  
Interferon Responses ◽  
Replication Intermediates

ABSTRACT Human noroviruses are responsible for more than 95% of nonbacterial epidemic gastroenteritis worldwide. Both onset and resolution of disease symptoms are rapid, suggesting that components of the innate immune response are critical in norovirus control. While the study of the human noroviruses has been hampered by the lack of small animal and tissue culture systems, our recent discovery of a murine norovirus (MNV) and its in vitro propagation have allowed us to begin addressing norovirus replication strategies and immune responses to norovirus infection. We have previously demonstrated that interferon responses are critical to control MNV-1 infection in vivo and to directly inhibit viral replication in vitro. We now extend these studies to define the molecular basis for interferon-mediated inhibition. Viral replication intermediates were not detected in permissive cells pretreated with type I interferon after either infection or transfection of virion-associated RNA, demonstrating a very early block to virion production that is after virus entry and uncoating. A similar absence of viral replication intermediates was observed in infected primary macrophages and dendritic cells pretreated with type I IFN. This was not due to degradation of incoming genomes in interferon-pretreated cells since similar levels of genomes were present in untreated and pretreated cells through 6 h of infection, and these genomes retained their integrity. Surprisingly, this block to the translation of viral proteins was not dependent on the well-characterized interferon-induced antiviral molecule PKR. Similar results were observed in cells pretreated with type II interferon, except that the inhibition of viral translation was dependent on PKR. Thus, both type I and type II interferon signaling inhibit norovirus translation in permissive myeloid cells, but they display distinct dependence on PKR for this inhibition.

scholarly journals Strategies to Investigate Membrane Damage, Nucleoid Condensation, and RNase Activity of Bacterial Toxin–Antitoxin Systems

2021 ◽  
Vol 4 (4) ◽  
pp. 71
Author(s):  
Stefano Maggi ◽  
Alberto Ferrari ◽  
Korotoum Yabre ◽  
Aleksandra Anna Bonini ◽  
Claudio Rivetti ◽  
...  
Keyword(s):  
Cell Transformation ◽  
Expression System ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Host Cells ◽  
Rnase Activity ◽  
Bacterial Toxin ◽  
Type I

A large number of bacterial toxin–antitoxin (TA) systems have been identified so far and different experimental approaches have been explored to investigate their activity and regulation both in vivo and in vitro. Nonetheless, a common feature of these methods is represented by the difficulty in cell transformation, culturing, and stability of the transformants, due to the expression of highly toxic proteins. Recently, in dealing with the type I Lpt/RNAII and the type II YafQ/DinJ TA systems, we encountered several of these problems that urged us to optimize methodological strategies to study the phenotype of recombinant Escherichia coli host cells. In particular, we have found conditions to tightly repress toxin expression by combining the pET expression system with the E. coli C41(DE3) pLysS strain. To monitor the RNase activity of the YafQ toxin, we developed a fluorescence approach based on Thioflavin-T which fluoresces brightly when complexed with bacterial RNA. Fluorescence microscopy was also applied to reveal loss of membrane integrity associated with the activity of the type I toxin Lpt, by using DAPI and ethidium bromide to selectively stain cells with impaired membrane permeability. We further found that atomic force microscopy can readily be employed to characterize toxin-induced membrane damages.

CD205, a target antigen for a novel antibody drug conjugate (ADC): Evaluation of antigen expression on non-Hodgkin lymphoma (NHL).

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e14039-e14039 ◽  
Author(s):  
Vincenzo Canzonieri ◽  
Valter Gattei ◽  
Michele Spina ◽  
Annalisa Polizzi-Anselmo ◽  
Nickolas Attanasio ◽  
...  
Keyword(s):  
Antigen Expression ◽  
Staining Intensity ◽  
Target Antigen ◽  
Type I ◽  
Antibody Drug Conjugate ◽  
Protein Motifs ◽  
Lectin Receptor ◽  
Non Hodgkin Lymphoma

e14039 Background: CD205 is a type I C-type lectin receptor normally expressed on various APC and some leukocyte sub-populations, characterized by a cytoplasmic domain containing protein motifs crucial for endocytosis and internalization. These features make CD205 ideal to be exploited as target of a novel ADC. MEN1309/OBT076 is a humanized IgG1 antibody against CD205, conjugated through a cleavable linker to a potent maytansinoid microtubule disruptor, DM4. Indeed, impressive results were obtained in high and low CD205 expressing xenografts for solid tumours and NHL. In vitro experimental model describing the by-stander effect of MEN1309 was implemented. Methods:A retrospective analysis to evaluate the CD205 expression on archival NHL biopsies was performed in the CRO-National Cancer Institute, Aviano IT. An immunohistochemistry (IHC) was performed on 1 slide per case, using a commercial antibody NCL-L-DEC205 (clone 11A10, Leica Biosystems). All slides were visually evaluated and a validated staining scoring system was applied, ranging from negative score 0 to strong immunostaining score 3+. Percentages (from 0 to 100%) of negative and positive tumor cells (scored as follows: 1-25% = score 1; 26-50% = score 2; 51-75% = score 3; 76-100% = score 4) were reported for each individual slide.Evaluation of correlations between CD205 expression and clinical characteristics is ongoing. Results: 100 cases of Diffuse Large B Cells Lymphomas (DLBCL) and 33 of Follicular Lymphomas (FL) were analysed. 60% of DLBCL cases were positive for CD205 and 39% had more than 25% of positive cells (score ≥2), while the 16% showed 2+/3+ staining intensity. 79% of FL cases were CD205 positive and 66% had more than 25% of positive cells, while the 27% showed 2+/3+ staining intensity. Conclusions: CD205 is heterogeneously expressed in the majority of DLBCL and FL cases. Data on the correlation between CD205 expression and clinical features will be discussed.MEN1309 has shown anti-tumour activity in vitro and in vivo even in low antigen expressing tumours. Hence CD205 expression among NHL, even if heterogeneous, makes, both DLBCL and FL, promising settings in which to explore MEN1309 activity in an upcoming FIH trial.

scholarly journals Y-RNAs Lead an Endogenous Program of RIG-I Agonism Mobilized upon RNA Virus Infection and Targeted by HIV

2019 ◽  
Author(s):  
Nicolas Vabret ◽  
Valérie Najburg ◽  
Alexander Solovyov ◽  
Petr Šulc ◽  
Sreekumar Balan ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Cell Activation ◽  
Rna Virus ◽  
Type I ◽  
Endogenous Ligands ◽  
Rna Triphosphatase ◽  
Molecular Patterns ◽  
Hiv 1

AbstractPattern recognition receptors (PRRs) protect against host invasion by detecting specific molecular patterns found in pathogens and initiating an immune response. While microbial-derived PRR ligands have been extensively characterized, the contribution and relevance of endogenous ligands to PRR activation during viral infection remain overlooked. In this work, we characterize the landscape of endogenous ligands that engage RIG-I-like receptors (RLRs) upon infection by a positive-sense RNA virus, a negative-sense RNA virus or a retrovirus. We found that several endogenous RNAs transcribed by RNA polymerase 3 (Pol3) specifically engage RLRs, and in particular the family of small non-coding repeats Y-RNAs, which presents the highest affinity as RIG-I ligands. We show that this recognition is dependent on Y-RNA mimicking viral secondary structure and its 5’-triphosphate extremity. Further, we found that HIV-1 infection triggers a VPR-dependent downregulation of RNA triphosphatase DUSP11 in vitro and in vivo, leading to an increase of Y-RNA 5’-triphosphorylation that enables their immunogenicity. Importantly, we show that altering DUSP11 expression is sufficient to induce a type-I interferon and T cell activation transcriptional program associated with HIV-1 infection. Overall, our work uncovers the critical contribution of endogenous repeat RNAs ligands to antiviral immunity and demonstrates the role of this pathway in HIV-1 infection.

scholarly journals AMA1-Deficient Toxoplasma gondii Parasites Transiently Colonize Mice and Trigger an Innate Immune Response That Leads to Long-Lasting Protective Immunity

2015 ◽  
Vol 83 (6) ◽  
pp. 2475-2486 ◽  
Author(s):  
Vanessa Lagal ◽  
Márcia Dinis ◽  
Dominique Cannella ◽  
Daniel Bargieri ◽  
Virginie Gonzalez ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Distinct Type ◽  
Genetically Engineered ◽  
Host Cells ◽  
Type I ◽  
Content Type ◽  
Apical Membrane Antigen 1 ◽  
Immunocompromised Mice

The apical membrane antigen 1 (AMA1) protein was believed to be essential for the perpetuation of two Apicomplexa parasite genera,PlasmodiumandToxoplasma, until we genetically engineered viable parasites lackingAMA1. The reduction in invasiveness of theToxoplasma gondiiRH-AMA1 knockout (RH-AMA1KO) tachyzoite population,in vitro, raised key questions about the outcome associated with these tachyzoites once inoculated in the peritoneal cavity of mice. In this study, we used AMNIS technology to simultaneously quantify and image the parasitic process driven by AMA1KOtachyzoites. We report their ability to colonize and multiply in mesothelial cells and in both resident and recruited leukocytes. While the RH-AMA1KOpopulation amplification is rapidly lethal in immunocompromised mice, it is controlled in immunocompetent hosts, where immune cells in combination sense parasites and secrete proinflammatory cytokines. This innate response further leads to a long-lasting status immunoprotective against a secondary challenge by high inocula of the homologous type I or a distinct type IIT. gondiigenotypes. While AMA1 is definitively not an essential protein for tachyzoite entry and multiplication in host cells, it clearly assists the expansion of parasite populationin vivo.

scholarly journals Interferons: Tug of War Between Bacteria and Their Host

2021 ◽  
Vol 11 ◽  
Author(s):  
Noémie Alphonse ◽  
Ruth E. Dickenson ◽  
Charlotte Odendall
Keyword(s):  
Signaling Pathways ◽  
Bacterial Infections ◽  
Host Cells ◽  
Host Responses ◽  
Bacterial Invasion ◽  
Type I ◽  
Viral Immunity ◽  
Diverse Range

Type I and III interferons (IFNs) are archetypally antiviral cytokines that are induced in response to recognition of foreign material by pattern recognition receptors (PRRs). Though their roles in anti-viral immunity are well established, recent evidence suggests that they are also crucial mediators of inflammatory processes during bacterial infections. Type I and III IFNs restrict bacterial infection in vitro and in some in vivo contexts. IFNs mainly function through the induction of hundreds of IFN-stimulated genes (ISGs). These include PRRs and regulators of antimicrobial signaling pathways. Other ISGs directly restrict bacterial invasion or multiplication within host cells. As they regulate a diverse range of anti-bacterial host responses, IFNs are an attractive virulence target for bacterial pathogens. This review will discuss the current understanding of the bacterial effectors that manipulate the different stages of the host IFN response: IFN induction, downstream signaling pathways, and target ISGs.

scholarly journals Utility of SARS-CoV-2 infection models using in vitro and in vivo ACE2-lentivirus transduction

2021 ◽  
Author(s):  
Daniel J. Rawle ◽  
Thuy Le ◽  
Troy Dumenil ◽  
Kexin Yan ◽  
Bing Tang ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Type I ◽  
Rna Seq ◽  
Permissive Cell ◽  
Lentiviral Transduction ◽  
Infection Models ◽  
Lentivirus Transduction ◽  
Interferon Responses

SUMMARYSARS-CoV-2 uses the human ACE2 (hACE2) receptor, with mouse ACE2 (mACE2) unable to support infection. Herein we describe an ACE2-lentivirus system and illustrate its utility for in vitro and in vivo SARS-CoV-2 infection models. Transduction of non-permissive cell lines with hACE2 imparted replication competence, and transduction with mACE2 containing N30D, N31K, F83Y and H353K substitutions, to match hACE2, rescued SARS-CoV-2 replication. hACE2-lentivirus transduction of C57BL/6J, IFNAR-/- and IL-28RA-/- mice lungs illustrated that removing type I or III interferon responses had no significant effect on virus replication. However, RNA-Seq analyses illustrated they were required for the inflammatory responses, which were similar to those seen in COVID-19 patients. We also illustrate the utility of hACE2 transduction for vaccine evaluation in C57BL/6J mice. In summary, we establish a hACE2-lentivirus mouse model which has broad application in SARS-CoV-2 research, while also offering the inherent advantages of lentiviral transduction such as stable genomic integration.

scholarly journals ACE2-lentiviral transduction enables mouse SARS-CoV-2 infection and mapping of receptor interactions

2021 ◽  
Vol 17 (7) ◽  
pp. e1009723
Author(s):  
Daniel J. Rawle ◽  
Thuy T. Le ◽  
Troy Dumenil ◽  
Kexin Yan ◽  
Bing Tang ◽  
...  
Keyword(s):  
Virus Replication ◽  
Inflammatory Responses ◽  
Cell Attachment ◽  
Model Development ◽  
Type I ◽  
Rna Seq ◽  
Lentivirus Transduction ◽  
Interferon Responses

SARS-CoV-2 uses the human ACE2 (hACE2) receptor for cell attachment and entry, with mouse ACE2 (mACE2) unable to support infection. Herein we describe an ACE2-lentivirus system and illustrate its utility for in vitro and in vivo SARS-CoV-2 infection models. Transduction of non-permissive cell lines with hACE2 imparted replication competence, and transduction with mACE2 containing N30D, N31K, F83Y and H353K substitutions, to match hACE2, rescued SARS-CoV-2 replication. Intrapulmonary hACE2-lentivirus transduction of C57BL/6J mice permitted significant virus replication in lung epithelium. RNA-Seq and histological analyses illustrated that this model involved an acute inflammatory disease followed by resolution and tissue repair, with a transcriptomic profile similar to that seen in COVID-19 patients. hACE2-lentivirus transduction of IFNAR-/- and IL-28RA-/- mouse lungs was used to illustrate that loss of type I or III interferon responses have no significant effect on virus replication. However, their importance in driving inflammatory responses was illustrated by RNA-Seq analyses. We also demonstrate the utility of the hACE2-lentivirus transduction system for vaccine evaluation in C57BL/6J mice. The ACE2-lentivirus system thus has broad application in SARS-CoV-2 research, providing a tool for both mutagenesis studies and mouse model development.

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