scholarly journals TLR3-Dependent Activation of TLR2 Endogenous Ligands via the MyD88 Signaling Pathway Augments the Innate Immune Response

Cells ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1910
Author(s):  
Hellen S. Teixeira ◽  
Jiawei Zhao ◽  
Ethan Kazmierski ◽  
Denis F. Kinane ◽  
Manjunatha R. Benakanakere
Keyword(s):  
Signaling Pathway ◽  
Innate Immune ◽  
Poly I:C ◽  
Innate Immune Responses ◽  
Endogenous Ligands ◽  
Polyinosinic:Polycytidylic Acid ◽  
Tlr3 Signaling ◽  
Myd88 Signaling

The role of the adaptor molecule MyD88 is thought to be independent of Toll-like receptor 3 (TLR3) signaling. In this report, we demonstrate a previously unknown role of MyD88 in TLR3 signaling in inducing endogenous ligands of TLR2 to elicit innate immune responses. Of the various TLR ligands examined, the TLR3-specific ligand polyinosinic:polycytidylic acid (poly I:C), significantly induced TNF production and the upregulation of other TLR transcripts, in particular, TLR2. Accordingly, TLR3 stimulation also led to a significant upregulation of endogenous TLR2 ligands mainly, HMGB1 and Hsp60. By contrast, the silencing of TLR3 significantly downregulated MyD88 and TLR2 gene expression and pro-inflammatory IL1β, TNF, and IL8 secretion. The silencing of MyD88 similarly led to the downregulation of TLR2, IL1β, TNF and IL8, thus suggesting MyD88 to somehow act downstream of TLR3. Corroborating in vitro data, Myd88−/− knockout mice downregulated TNF, CXCL1; and phospho-p65 and phospho-IRF3 nuclear localization, upon poly I:C treatment in a mouse model of skin infection. Taken together, we identified a previously unknown role for MyD88 in the TLR3 signaling pathway, underlying the importance of TLRs and adapter protein interplay in modulating endogenous TLR ligands culminating in pro-inflammatory cytokine regulation.

scholarly journals Role of MDA5 in regulating CXCL10 expression induced by TLR3 signaling in human rheumatoid fibroblast-like synoviocytes

2021 ◽  
Author(s):  
Tatsuro Saruga ◽  
Tadaatsu Imaizumi ◽  
Shogo Kawaguchi ◽  
Kazuhiko Seya ◽  
Tomoh Matsumiya ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Neutralizing Antibody ◽  
Poly I:C ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Inflammatory Reactions ◽  
Polyinosinic:Polycytidylic Acid ◽  
Tlr3 Signaling ◽  
Fibroblast Like Synoviocytes

AbstractC-X-C motif chemokine 10 (CXCL10) is an inflammatory chemokine and a key molecule in the pathogenesis of rheumatoid arthritis (RA). Melanoma differentiation-associated gene 5 (MDA5) is an RNA helicase that plays a role in innate immune and inflammatory reactions. The details of the regulatory mechanisms of CXCL10 production and the precise role of MDA5 in RA synovitis have not been fully elucidated. The aim of this study was to examine the role of MDA5 in regulating CXCL10 expression in cultured human rheumatoid fibroblast-like synoviocytes (RFLS). RFLS was stimulated with Toll-like receptor 3 (TLR3) ligand polyinosinic:polycytidylic acid (poly I:C), a synthetic double-stranded RNA mimetic. Expression of interferon beta (IFN-β), MDA5, and CXCL10 was measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting, and enzyme-linked immunosorbent assay. A neutralizing antibody of IFN-β and siRNA-mediated MDA5 knockdown were used to determine the role of these molecules in regulating CXCL10 expression downstream of TLR3 signaling in RFLS. Poly I:C induced IFN-β, MDA5, and CXCL10 expression in a concentration- and time-dependent manner. IFN-β neutralizing antibody suppressed the expression of MDA5 and CXCL10, and knockdown of MDA5 decreased a part of CXCL10 expression (p < 0.001). The TLR3/IFN-β/CXCL10 axis may play a crucial role in the inflammatory responses in RA synovium, and MDA5 may be partially involved in this axis.

scholarly journals An In Vitro Assessment of Immunostimulatory Responses to Ten Model Innate Immune Response Modulating Impurities (IIRMIs) and Peptide Drug Product, Teriparatide

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7461
Author(s):  
Claire K. Holley ◽  
Edward Cedrone ◽  
Duncan Donohue ◽  
Barry W. Neun ◽  
Daniela Verthelyi ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Cytokine Secretion ◽  
Poly I:C ◽  
In Vitro Assays ◽  
Innate Immune Responses ◽  
Vitro Assay

Understanding, predicting, and minimizing the immunogenicity of peptide-based therapeutics are of paramount importance for ensuring the safety and efficacy of these products. The so-called anti-drug antibodies (ADA) may have various clinical consequences, including but not limited to the alteration in the product’s distribution, biological activity, and clearance profiles. The immunogenicity of biotherapeutics can be influenced by immunostimulation triggered by the presence of innate immune response modulating impurities (IIRMIs) inadvertently introduced during the manufacturing process. Herein, we evaluate the applicability of several in vitro assays (i.e., complement activation, leukocyte proliferation, and cytokine secretion) for the screening of innate immune responses induced by ten common IIRMIs (Bacillus subtilis flagellin, FSL-1, zymosan, ODN2006, poly(I:C) HMW, poly(I:C) LMW, CLO75, MDP, ODN2216, and Escherichia coli O111:B4 LPS), and a model biotherapeutic Forteo™ (teriparatide). Our study identifies cytokine secretion from healthy human donor peripheral blood mononuclear cells (PBMC) as a sensitive method for the in vitro monitoring of innate immune responses to individual IIRMIs and teriparatide (TP). We identify signature cytokines, evaluate both broad and narrow multiplex cytokine panels, and discuss how the assay logistics influence the performance of this in vitro assay.

scholarly journals Long Non-coding RNAs RN7SK and GAS5 Regulate Macrophage Polarization and Innate Immune Responses

2020 ◽  
Vol 11 ◽  
Author(s):  
Imran Ahmad ◽  
Araceli Valverde ◽  
Raza Ali Naqvi ◽  
Afsar R. Naqvi
Keyword(s):  
Immune Responses ◽  
Epigenetic Regulation ◽  
Innate Immune ◽  
Differentially Expressed ◽  
Immune Functions ◽  
Innate Immune Responses ◽  
Antigen Uptake ◽  
Non Coding Rnas

Macrophages (Mφ) are immune cells that exhibit remarkable functional plasticity. Identification of novel endogenous factors that can regulate plasticity and innate immune functions of Mφ will unravel new strategies to curb immune-related diseases. Long non-coding RNAs (lncRNAs) are a class of endogenous, non-protein coding, regulatory RNAs that are increasingly being associated with various cellular functions and diseases. Despite their ubiquity and abundance, lncRNA-mediated epigenetic regulation of Mφ polarization and innate immune functions is poorly studied. This study elucidates the regulatory role of lncRNAs in monocyte to Mφ differentiation, M1/M2 dichotomy and innate immune responses. Expression profiling of eighty-eight lncRNAs in monocytes and in vitro differentiated M2 Mφ identified seventeen differentially expressed lncRNAs. Based on fold-change and significance, we selected four differentially expressed lncRNAs viz., RN7SK, GAS5, IPW, and ZFAS1 to evaluate their functional impact. LncRNA knockdown was performed on day 3 M2 Mφ and the impact on polarization was assessed on day 7 by surface marker analysis. Knockdown of RN7SK and GAS5 showed downregulation of M2 surface markers (CD163, CD206, or Dectin) and concomitant increase in M1 markers (MHC II or CD23). RN7SK or GAS5 knockdown showed no significant impact on CD163, CD206, or CD23 transcripts. M1/M2 markers were not impacted by IPW or ZFAS1 knockdown. Functional regulation of antigen uptake/processing and phagocytosis, two central innate immune pathways, by candidate lncRNA was assessed in M1/M2 Mφ. Compared to scramble, enhanced antigen uptake and processing were observed in both M1/M2 Mφ transfected with siRNA targeting GAS5 and RN7SK but not IPW and ZFAS1. In addition, knockdown of RN7SK significantly augmented uptake of labelled E. coli in vitro by M1/M2 Mφ, while no significant difference was in GAS5 silencing cells. Together, our results highlight the instrumental role of lncRNA (RN7SK and GAS5)-mediated epigenetic regulation of macrophage differentiation, polarization, and innate immune functions.

scholarly journals Decoding the role of CBLB for innate immune responses regulating systemic dissemination during Non-Tuberculous Mycobacteria infection

2020 ◽  
Author(s):  
Srinivasu Mudalagiriyappa ◽  
Jaishree Sharma ◽  
Hazem F. M. Abdelaal ◽  
Thomas C. Kelly ◽  
Woosuk Choi ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Granulomatous Inflammation ◽  
Innate Immune ◽  
Dependent Manner ◽  
Innate Immune Responses ◽  
Inflammatory Monocytes ◽  
Cell Immunity

AbstractNon-Tuberculous Mycobacteria (NTM) are ubiquitous in nature, present in soil and water, and cause primary leading to disseminated infections in immunocompromised individuals. NTM infections are surging in recent years due to an increase in an immune-suppressed population, medical interventions, and patients with underlying lung diseases. Host regulators of innate immune responses, frontiers for controlling infections and dissemination, are poorly defined during NTM infections. Here, we describe the role of CBLB, an E3-ubiquitin ligase, for innate immune responses and disease progression in a mouse model of NTM infection under compromised T-cell immunity. We found that CBLB thwarted NTM growth and dissemination in a time- and infection route- dependent manner. Mechanistically, we uncovered defects in many innate immune cells in the absence of Cblb, including poor responses of NK cells, inflammatory monocytes, and conventional dendritic cells. Strikingly, Cblb-deficient macrophages were competent to control NTM growth in vitro. Histopathology suggested the lack of early formation of granulomatous inflammation in the absence of CBLB. Collectively, CBLB is essential to mount productive innate immune responses and help prevent the dissemination during an NTM infection under T-cell deficiency.

scholarly journals Genome-wide RNAi Screen Reveals a New Role of a WNT/CTNNB1 Signaling Pathway as Negative Regulator of Virus-induced Innate Immune Responses

2013 ◽  
Vol 9 (6) ◽  
pp. e1003416 ◽  
Author(s):  
Martin Baril ◽  
Salwa Es-Saad ◽  
Laurent Chatel-Chaix ◽  
Karin Fink ◽  
Tram Pham ◽  
...  
Keyword(s):  
Immune Responses ◽  
Signaling Pathway ◽  
Rnai Screen ◽  
Innate Immune ◽  
Negative Regulator ◽  
Innate Immune Responses ◽  
Genome Wide

scholarly journals Regulation of TRIF-mediated innate immune response by K27-linked polyubiquitination and deubiquitination

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xin Wu ◽  
Caoqi Lei ◽  
Tian Xia ◽  
Xuan Zhong ◽  
Qing Yang ◽  
...  
Keyword(s):  
Immune Responses ◽  
Adaptor Protein ◽  
Innate Immune ◽  
Negative Regulator ◽  
Type I Interferons ◽  
Poly I:C ◽  
Type I ◽  
Innate Immune Responses

Abstract TIR domain-containing adaptor inducing interferon-β (TRIF) is an essential adaptor protein required for innate immune responses mediated by Toll-like receptor (TLR) 3- and TLR4. Here we identify USP19 as a negative regulator of TLR3/4-mediated signaling. USP19 deficiency increases the production of type I interferons (IFN) and proinflammatory cytokines induced by poly(I:C) or LPS in vitro and in vivo. Usp19-/- mice have more serious inflammation after poly(I:C) or LPS treatment, and are more susceptible to inflammatory damages and death following Salmonella typhimurium infection. Mechanistically, USP19 interacts with TRIF and catalyzes the removal of TRIF K27-linked polyubiquitin moieties, thereby impairing the recruitment of TRIF to TLR3/4. In addition, the RING E3 ubiquitin ligase complex Cullin-3-Rbx1-KCTD10 catalyzes K27-linked polyubiquitination of TRIF at K523, and deficiency of this complex inhibits TLR3/4-mediated innate immune signaling. Our findings thus reveal TRIF K27-linked polyubiquitination and deubiquitination as a critical regulatory mechanism of TLR3/4-mediated innate immune responses.

scholarly journals Escape of TLR5 Recognition by Leptospira spp: A Rationale for Atypical Endoflagella

2020 ◽  
Author(s):  
Marion Holzapfel ◽  
Delphine Bonhomme ◽  
Julie Cagliero ◽  
Frédérique Vernel-Pauillac ◽  
Martine Fanton d’Andon ◽  
...  
Keyword(s):  
Innate Immune ◽  
Proteinase K ◽  
Innate Immune Responses ◽  
Conserved Residues ◽  
Proteinase K Treatment ◽  
Deficient Mice ◽  
Wall Components

AbstractLeptospira interrogans are invasive bacteria responsible for leptospirosis, a worldwide zoonosis. They possess two periplasmic endoflagella that allow their motility. L. interrogans are stealth pathogens that escape the innate immune responses of the NOD-like receptors NOD1/2, and the human Toll-like receptor (TLR)4, sensing peptidoglycan and lipopolysaccharide (LPS), respectively. TLR5 is another receptor of bacterial cell wall components, recognizing flagellin subunits.To study the contribution of TLR5 in the host defense against leptospires, we infected WT and TLR5 deficient mice with pathogenic L. interrogans and tracked the infection by in vivo live imaging of bioluminescent bacteria or by q-PCR. We did not identify any protective or inflammatory role of murine TLR5 to control pathogenic Leptospira. Likewise, subsequent in vitro experiments showed that infections with different live strains of L. interrogans and L. biflexa did not trigger TLR5. However, unexpectedly, heat-killed bacteria stimulated human and bovine TLR5, although barely mouse TLR5. Abolition of TLR5 recognition required extensive boiling time of the bacteria or proteinase K treatment, showing an unusual high stability of the leptospiral flagellins. Interestingly, using antimicrobial peptides to destabilize live leptospires, we detected some TLR5 activity, suggesting that TLR5 could participate in the fight against leptospires in humans or cattle. Using different Leptospira strains with mutations in flagellin proteins, we further showed that neither FlaAs nor Fcps participated in the recognition by TLR5, suggesting a role for the FlaBs. These have structural homology to Salmonella FliC, and conserved residues important for TLR5 activation, as shown by in silico analyses. Accordingly, we found that leptospires regulate the expression of FlaB mRNA according to the growth phase in vitro, and that infection with L. interrogans in hamsters and in mice downregulated the expression of the FlaBs but not the FlaAs subunits.Altogether, in contrast to different bacteria that modify their flagellin sequences to escape TLR5 recognition, our study suggests that the peculiar central localization and stability of the FlaB monomers in the periplasmic endoflagella, associated with the downregulation of FlaB subunits in hosts, constitute an efficient strategy of leptospires to escape TLR5 recognition and the immune response.

ISG12 Is a Critical Modulator of Innate Immune Responses in Animal Models of Septis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1274-1274
Author(s):  
Gernot Schabbauer ◽  
Nikolina Papac-Milicevic ◽  
Pavel Uhrin ◽  
Bernd Binder
Keyword(s):  
Immune Responses ◽  
Nuclear Receptors ◽  
Nuclear Export ◽  
Innate Immune ◽  
Experimental Sepsis ◽  
Innate Immune Responses ◽  
Anti Inflammatory ◽  
Deficient Mice

Abstract Sepsis is still a major burden for the society with a high incidence of morbidity and mortality each year. Molecular mechanisms underlying the systemic inflammatory response syndrome (SIRS) associated with sepsis are still ill defined and most therapies developed to target the acute inflammatory component of the disease are insufficent. Recently the role of nuclear receptors (NRs) in transcriptional regulation of inflammatory processes became a major topic of interest. Nuclear receptors, such as the peroxisome proliferators-activated receptors (PPARs), have been found to exert anti-inflammatory properties by interfering with the NFkB pathway. We are interested in the nuclear envelope protein, interferon stimulated gene 12 (ISG12), which directly interacts with NRs. ISG12 is a co-factor stimulating nuclear export of NRs, thereby reducing the anti-inflammatory potential of NRs such as PPARg or NR4A1. To examine the role of ISG12 in acute inflammation we generated ISG12 deficient mice. We can demonstrate by reverse genetics in ISG12 deficient mice that lack of ISG12 is beneficial in experimental sepsis and endotoxemia. Furthermore we can show that several acute inflammatory parameters, such as systemic IL6 cytokine levels, are downregulated in septic ISG12-/- animals. Consistently, similar results could be obtained in in vitro experiments in peritoneal macrophages derived from ISG12 deficient mice. In contrast, mice deficient for the nuclear receptor NR4A1 exhibited an exacerbated innate immune response and showed a significantly higher mortality after lethal septic challenge. This dramatic phenotype could be restored in ISG12/NR4A1 double deficient mice. We conclude from our data in vitro and in vivo that ISG12 is a novel modulator of innate immune responses regulating anti-inflammatory nuclear receptors such as NR4A1.

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