scholarly journals The lectin-specific activity of Toxoplasma gondii microneme proteins 1 and 4 binds Toll-like receptor 2 and 4 N-glycans to regulate innate immune priming

2017 ◽  
Author(s):  
Aline Sardinha-Silva ◽  
Flávia C. Mendonça-Natividade ◽  
Camila F. Pinzan ◽  
Carla D. Lopes ◽  
Diego L. Costa ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Immune Cells ◽  
Point Mutations ◽  
Innate Immune ◽  
Host Cells ◽  
Apical Region ◽  
Innate Immune Cells ◽  
Active Process ◽  
Microneme Proteins

ABSTRACTInfection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex, secreted on the parasite surface and function to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages to produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-γ in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis.AUTHOR SUMMARYToxoplasmosis is caused by the protozoan Toxoplasma gondii, belonging to the Apicomplexa phylum. This phylum comprises important parasites able to infect a broad diversity of animals, including humans. A particularity of T. gondii is its ability to invade virtually any nucleated cell of all warm-blooded animals through an active process, which depends on the secretion of adhesin proteins. These proteins are discharged by specialized organelles localized in the parasite apical region, and termed micronemes and rhoptries. We show in this study that two microneme proteins from T. gondii utilize their adhesion activity to stimulate innate immunity. These microneme proteins, denoted MIC1 and MIC4, recognize specific sugars on receptors expressed on the surface of mammalian immune cells. This binding activates these innate immune cells to secrete cytokines, which promotes efficient host defense mechanisms against the parasite and regulate their pathogenesis. This activity promotes a chronic infection by controlling parasite replication during acute infection.

Abstract 1772: Cardiomyocyte Damage-Released S100A1 Protein Evokes A Proinflammatory Phenotype In Cardiac Fibroblasts

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
David Rohde ◽  
Melanie Boerries ◽  
Herzog Nicole ◽  
Gang Qiu ◽  
Philipp Ehlermann ◽  
...  
Keyword(s):  
Western Blotting ◽  
Immune Cells ◽  
Nuclear Translocation ◽  
Cardiac Fibroblasts ◽  
Innate Immune ◽  
Host Cells ◽  
Boyden Chamber ◽  
Innate Immune Cells ◽  
Danger Signal

Background: S100A1, a cardiomyocyte specific inotropic calcium sensor protein, is released from infarcted human myocardium in the extracellular environment and circulation, reaching peak serum levels (1–2 μM) 8–9 hours after clinical onset. As growing evidence indicates that S100 proteins can act as pre-existing danger signals triggering the innate immune system into action upon release from injured host cells, we hypothesized that damage-released S100A1 can act as a cardiac danger signal alerting innate immune cells. Methods and Results: Here we report for the first time that necrotic cardiomyocytes release S100A1 protein in vitro, which is exclusively internalized by cardiac fibroblasts (CFs) in a clathrin- and caveolin-independent manner as shown by IF. Internalized S100A1 specifically activated MAPKs/SAPKs (p38, ERK1/2 and JNK) resulting in nuclear translocation of p65 (NF-kB) as assessed by Western blotting, EMSA and IF. In turn, S100A1 triggered an inflammatory gene program in CFs including enhanced expression of adhesion molecules, integrins, chemokines and cytokines including I-CAM, V-CAM, CD11b/18, IL1-alpha, MCP-1, TNF-alpha, SDF-1 among others as obtained by RT-PCR, Western blotting and ELISA. This resulted in enhanced chemoattraction and adhesion of monocytotic and stem cells to S100A1-activated CF as shown by Boyden-chamber and adhesion assays. In line with their proinflammatory transition, S100A1-activated CFs exhibited decreased collagen-1/-3 expression and de-novo collagen production, enhanced collagenolytic MMP-9 abundance and activity and increased levels of the antiangiogenic matricellular factor thrombospondin-2 reflecting extracellular matrix net degradation. Importantly, the immun-modulatory and antifibrotic actions of S100A1 protein in vitro were restricted to CFs, RAGE independent and occurred at concentrations (0.1–1 μM) that were found in patients after AMI. Conclusion: Our in vitro results indicate that S100A1 has the properties of a pre-exisiting endogenous cardiomyocyte danger signal transforming cardiac fibroblasts into immunmodulatory cells that might recruit innate immune cells to the site of cardiac injury and link cardiomyocyte damage to post-MI inflammation.

Calreticulin Promotes Immunity Against Acute Myeloid Leukemia Cells in Vivo

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 996-996
Author(s):  
Xiufen Chen ◽  
Dominick Fosco ◽  
Douglas E. Kline ◽  
Justin Kline
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Surface ◽  
Vector Control ◽  
Immune Cells ◽  
Myeloid Leukemia ◽  
Innate Immune ◽  
Innate Immune Cells

Abstract Pre-apoptotic cancer cells release internalized calreticulin (CRT) to their surface prior to death, which acts as an ‘eat-me’ signal to local phagocytes. Chemotherapy and irradiation, which can induce immunogenic cell death through CRT translocation, can also result in local and/or systemic immune suppression in the host. To bypass the requirement of exposing the host to chemotherapy to induce translocation of CRT to the cell surface, murine acute myeloid leukemia (AML) cells (C1498), were engineered to constitutively express cell surface CRT (C1498.CRT). Vector control C1498 or C1498.CRT cells were inoculated intravenously (IV) into C57BL/6 mice. Significantly prolonged survival was observed in hosts harboring C1498.CRT versus vector control C1498 cells systemically. The survival benefit were abrogated in both Rag2-/- hosts or by depletion of T cells with anti-CD4 plus anti-CD8 antibodies, arguing that the immune-mediated effect of cell-surface CRT expression is dependent upon a functional adaptive immune system. More strikingly, systemic inoculation with C1498.CRT cells expressing the model SIYRYYGL (SIY) peptide antigen (C1498.SIY.CRT cells) resulted in almost complete protection from AML development (>90% long term survival vs. 10% of C1498.SIY vector control cells). All animals surviving a primary C1498.SIY.CRT challenge rejected a subsequent re-challenge with C1498.SIY cells, suggesting that CRT-expressing AML cells promote immunologic memory. Significantly enhanced expansion and unregulated IFNγ production were observed among SIY-specific T cell receptor transgenic CD8+ 2C T cells following their adoptive transfer into hosts bearing C1498.SIY.CRT AML cells versus vector control C1498.SIY cells. Interestingly, CRT expression on AML cells did not promote their in vivo phagocytosis by innate immune cells, specifically splenic CD8a+ dendritic cells known to engulf AML cells following their IV inoculation. IL-12 production by CD8α+CD11c+ dendritic cells which had engulfed C1498 and C1498.CRT cells in vivo was similarly induced, and cross-presentation of the SIY antigen to 2C T cells ex vivo by purified CD8a+DCs following in vivo exposure to C1498.SIY or C1498.SIY.CRT cells was also similar. In conclusion, it is clear that expression on CRT on the surface of AML cells leads to robust leukemia-specific T cell activation and expansion resulting in prolonged leukemia-specific survival in AML-bearing animals. Although a direct effect of CRT on innate immune cells, such as dendritic cells, is suspected, the molecular mechanism underlying the “CRT effect” remains unclear, and is being explored further through gene expression analysis in purified DCs which have engulfed CRT-expressing or control AML cells in vivo, as well as in animals genetically deficient in the putative CRT receptor, LRP, in dendritic cells. It will be of interest to analyze spontaneous CRT expression on AML cells from human samples and to correlate cell surface CRT expression with the presence or absence of spontaneous T cell responses to known AML antigens and with clinical outcomes. Disclosures No relevant conflicts of interest to declare.

scholarly journals Interfering with MIF-CD74 signalling on macrophages and dendritic cells with a peptide-based approach restores the immune response against metastatic melanoma

2018 ◽  
Author(s):  
Carlos R. Figueiredo ◽  
Ricardo A. Azevedo ◽  
Sasha Mousdell ◽  
Pedro T. Resende-Lara ◽  
Lucy Ireland ◽  
...  
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Metastatic Melanoma ◽  
Immune Cells ◽  
Tumour Microenvironment ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Adaptive Immune Cells ◽  
Cancer Immunotherapies

ABSTRACTMounting an effective immune response against cancer requires the activation of innate and adaptive immune cells. Metastatic melanoma is the most aggressive form of skin cancer. Immunotherapies that boost the activity of effector T cells have shown a remarkable success in melanoma treatment. Patients, however, can develop resistance to such therapies by mechanisms that include the establishment of an immune suppressive tumour microenvironment. Understanding how metastatic melanoma cells suppress the immune system is vital to develop effective immunotherapies against this disease. In this study, we find that the innate immune cells, macrophages and dendritic cells are suppressed in metastatic melanoma. The Ig-CDR-based peptide C36L1 is able to restore macrophages and dendritic cells’ immunogenic functions and to inhibit metastatic growth in vivo. Mechanistically, we found that C36L1 interferes with the MIF-CD74 tumour-innate immune cells immunosuppressive signalling pathway and thereby restores an effective anti-tumour immune response. C36L1 directly binds to CD74 on macrophages and dendritic cells, disturbing CD74 structural dynamics and inhibiting MIF signalling through CD74. Our findings suggest that interfering with MIF-CD74 immunosuppressive signalling in macrophages and dendritic cells using peptide-based immunotherapy can restore the anti-tumour immune response in metastatic melanoma. Our study provides the rationale for further development of peptide-based therapies to restore the anti-tumour immune response.

scholarly journals The Role of Syk/CARD9-Coupled C-Type Lectin Receptors in Immunity toMycobacterium tuberculosisInfections

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Mohlopheni Jackson Marakalala ◽  
Lisa M. Graham ◽  
Gordon D. Brown
Keyword(s):  
Immune Response ◽  
Pattern Recognition ◽  
Mycobacterium Tuberculosis ◽  
Immune Cells ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Lectin Receptors ◽  
Molecular Patterns

There is increasing interest in understanding the mechanisms underlying the interactions that occur betweenMycobacterium tuberculosisand host innate immune cells. These cells express pattern recognition receptors (PRRs) which recognise mycobacterial pathogen-associated molecular patterns (PAMPs) and which can influence the host immune response to the infection. Although many of the PRRs appear to be redundant in the control ofM. tuberculosisinfectionin vivo, recent discoveries have revealed a key, nonredundant, role of the Syk/CARD9 signalling pathway in antimycobacterial immunity. Here we review these discoveries, as well as recent data investigating the role of the Syk/CARD9-coupled PRRs that have been implicated in mycobacterial recognition, including Dectin-1 and Mincle.

scholarly journals Light Guided In-vivo Activation of Innate Immune Cells with Photocaged TLR 2/6 Agonist

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Keun Ah Ryu ◽  
Bethany McGonnigal ◽  
Troy Moore ◽  
Tawnya Kargupta ◽  
Rock J. Mancini ◽  
...  
Keyword(s):  
Immune Cells ◽  
Innate Immune ◽  
Innate Immune Cells

scholarly journals Trained Immunity

2020 ◽  
Author(s):  
Helin Tercan ◽  
Niels P. Riksen ◽  
Leo A.B. Joosten ◽  
Mihai G. Netea ◽  
Siroon Bekkering
Keyword(s):  
Immune Cells ◽  
Inflammatory Diseases ◽  
Oxidized Ldl ◽  
Density Lipoprotein ◽  
Innate Immune ◽  
Immune Memory ◽  
Innate Immune Cells ◽  
Antigen Specificity ◽  
Trained Immunity

Adaptive immune responses are characterized by antigen specificity and induction of lifelong immunologic memory. Recently, it has been reported that innate immune cells can also build immune memory characteristics—a process termed trained immunity. Trained immunity describes the persistent hyperresponsive phenotype that innate immune cells can develop after brief stimulation. Pathogenic stimuli such as microorganisms, and also endogenous molecules including uric acid, oxidized LDL (low-density lipoprotein), and catecholamines, are capable of inducing memory in monocytes and macrophages. While trained immunity provides favorable cross-protection in the context of infectious diseases, the heightened immune response can be maladaptive in diseases driven by chronic systemic inflammation, such as atherosclerosis. Trained immunity is maintained by distinct epigenetic and metabolic mechanisms and persists for at least several months in vivo due to reprogramming of myeloid progenitor cells. Additionally, certain nonimmune cells are also found to exhibit trained immunity characteristics. Thus, trained immunity presents an exciting framework to develop new approaches to vaccination and also novel pharmacological targets in the treatment of inflammatory diseases.

scholarly journals LPS Induces Opposing Memory-like Inflammatory Responses in Mouse Bone Marrow Neutrophils

2021 ◽  
Vol 22 (18) ◽  
pp. 9803
Author(s):  
Trim Lajqi ◽  
Maylis Braun ◽  
Simon Alexander Kranig ◽  
David Frommhold ◽  
Johannes Pöschl ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Immune Cells ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
In Vivo Studies ◽  
Mouse Bone Marrow ◽  
Innate Immune Cells ◽  
Trained Immunity

A growing body of evidence suggests that innate immune cells can respond in a memory-like (adaptive) fashion, which is referred to as trained immunity. Only few in vivo studies have shown training effects in neutrophils; however, no in vitro setup has been established to study the induction of trained immunity or tolerance in neutrophils by microbial agents. In light of their short lifespan (up to 48 h), we suggest to use the term trained sensitivity for neutrophils in an in vitro setting. Here, we firstly describe a feasible two-hit model, using different doses of lipopolysaccharide (LPS) in bone marrow neutrophils. We found that low doses (10 pg/mL) induce pro-inflammatory activation (trained sensitivity), whereas priming with high doses (100 ng/mL) leads to suppression of pro-inflammatory mediators such as TNF-α or IL-6 (tolerance) (p < 0.05). On a functional level, trained neutrophils displayed increased phagocytic activity and LFA-1 expression as well as migrational capacity and CD11a expression, whereas tolerant neutrophils show contrasting effects in vitro. Mechanistically, TLR4/MyD88/PI3Ks regulate the activation of p65, which controls memory-like responses in mouse bone marrow neutrophils (p < 0.05). Our results open a new window for further in vitro studies on memory-like inflammatory responses of short-lived innate immune cells such as neutrophils.

scholarly journals YAP-mediated mechanotransduction tunes the macrophage inflammatory response

2020 ◽  
Vol 6 (49) ◽  
pp. eabb8471
Author(s):  
Vijaykumar S. Meli ◽  
Hamza Atcha ◽  
Praveen Krishna Veerasubramanian ◽  
Raji R. Nagalla ◽  
Thuy U. Luu ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Immune Cells ◽  
Soft Materials ◽  
Innate Immune ◽  
Substrate Stiffness ◽  
Innate Immune Cells ◽  
Transcriptional Coactivator ◽  
Matrix Properties ◽  
Health And Disease

Macrophages are innate immune cells that adhere to the extracellular matrix within tissues. However, how matrix properties regulate their function remains poorly understood. Here, we report that the adhesive microenvironment tunes the macrophage inflammatory response through the transcriptional coactivator YAP. We find that adhesion to soft hydrogels reduces inflammation when compared to adhesion on stiff materials and is associated with reduced YAP expression and nuclear localization. Substrate stiffness and cytoskeletal polymerization, but not adhesive confinement nor contractility, regulate YAP localization. Furthermore, depletion of YAP inhibits macrophage inflammation, whereas overexpression of active YAP increases inflammation. Last, we show in vivo that soft materials reduce expression of inflammatory markers and YAP in surrounding macrophages when compared to stiff materials. Together, our studies identify YAP as a key molecule for controlling inflammation and sensing stiffness in macrophages and may have broad implications in the regulation of macrophages in health and disease.

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