scholarly journals Constitutively Activated DAP12 Induces Functional Anti-Tumor Activation and Maturation of Human Monocyte-Derived DC

2021 ◽  
Vol 22 (3) ◽  
pp. 1241
Author(s):  
Robert Dalton ◽  
Alexandra Calescibetta ◽  
Jun Min Zhou ◽  
Michelle Maurin ◽  
Grace Ward ◽  
...  
Keyword(s):  
Immune Response ◽  
Antigen Presenting Cells ◽  
Human Monocyte ◽  
Tumor Burden ◽  
Strong Immune Response ◽  
Cross Presentation ◽  
Dc Vaccine ◽  
Antigen Presenting ◽  
Constitutively Active

Dendritic cells (DCs) are professional antigen presenting cells with a great capacity for cross-presentation of exogenous antigens from which robust anti-tumor immune responses ensue. However, this function is not always available and requires DCs to first be primed to induce their maturation. In particular, in the field of DC vaccine design, currently available methodologies have been limited in eliciting a sustained anti-tumor immune response. Mechanistically, part of the maturation response is influenced by the presence of stimulatory receptors relying on ITAM-containing activating adaptor molecules like DAP12, that modulates their function. We hypothesize that activating DAP12 in DC could force their maturation and enhance their potential anti-tumor activity for therapeutic intervention. For this purpose, we developed constitutively active DAP12 mutants that can promote activation of monocyte-derived DC. Here we demonstrate its ability to induce the maturation and activation of monocyte-derived DCs which enhances migration, and T cell stimulation in vitro using primary human cells. Moreover, constitutively active DAP12 stimulates a strong immune response in a murine melanoma model leading to a reduction of tumor burden. This provides proof-of-concept for investigating the pre-activation of antigen presenting cells to enhance the effectiveness of anti-tumor immunotherapies.

scholarly journals Selective tumor antigen vaccine delivery to human CD169+antigen-presenting cells using ganglioside-liposomes

2020 ◽  
Vol 117 (44) ◽  
pp. 27528-27539
Author(s):  
Alsya J. Affandi ◽  
Joanna Grabowska ◽  
Katarzyna Olesek ◽  
Miguel Lopez Venegas ◽  
Arnaud Barbaria ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Antigen ◽  
Tumor Antigens ◽  
Ex Vivo ◽  
Antigen Presenting Cells ◽  
Dependent Manner ◽  
Cross Presentation ◽  
Vaccine Carrier ◽  
Antigen Presenting

Priming of CD8+T cells by dendritic cells (DCs) is crucial for the generation of effective antitumor immune responses. Here, we describe a liposomal vaccine carrier that delivers tumor antigens to human CD169/Siglec-1+antigen-presenting cells using gangliosides as targeting ligands. Ganglioside-liposomes specifically bound to CD169 and were internalized by in vitro-generated monocyte-derived DCs (moDCs) and macrophages and by ex vivo-isolated splenic macrophages in a CD169-dependent manner. In blood, high-dimensional reduction analysis revealed that ganglioside-liposomes specifically targeted CD14+CD169+monocytes and Axl+CD169+DCs. Liposomal codelivery of tumor antigen and Toll-like receptor ligand to CD169+moDCs and Axl+CD169+DCs led to cytokine production and robust cross-presentation and activation of tumor antigen-specific CD8+T cells. Finally, Axl+CD169+DCs were present in cancer patients and efficiently captured ganglioside-liposomes. Our findings demonstrate a nanovaccine platform targeting CD169+DCs to drive antitumor T cell responses.

Nitrosylation of Platelet MHC Class I Molecules Directs Their Movement into the Immunosuppressive MHC Class I Processing Pathway within Antigen Presenting Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 837-837
Author(s):  
John W. Semple ◽  
Edwin R. Speck ◽  
John Freedman
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Brefeldin A ◽  
Antigen Presenting Cells ◽  
Class I ◽  
Antigen Presenting ◽  
Platelet Transfusions

Abstract Previous studies have demonstrated that recipient mice require the production of nitric oxide (NO) within their antigen presenting cells (APC) in order to generate IgG anti-donor immunity against allogeneic platelet transfusions. NO has a complex biochemistry and several of its conjurors could be involved in this response; the most obvious is peroxynitrite (ONOO-) generated by the spontaneous combination of NO and superoxide (O2•−). ONOO- is a potent oxidant that can spontaneously nitrosylate lysine and tyrosine residues in proteins within the phagolysosome. To address the role of ONOO- in platelet immunity, we transfused GP91 PHOX knockout mice that lack the ability to produce O2•− and thus ONOO-. Results show that when wild type C57BL/6 mice were transfused with allogeneic BALB/c platelets, they developed a weak IgG anti-donor antibody response by the fifth transfusion. In contrast, PHOX KO mice generated IgG anti-donor antibodies by the 2nd transfusion and their IgG anti-donor antibody titres were significantly higher than the WT recipients. This suggested that ONOO- and protein nitrosylation may be linked with an immunosuppressive event within the recipient. This was confirmed by demonstrating that in vitro nitrosylation of platelet antigens with the ONOO- donor SIN-1 inhibited the ability of the platelets to mount an IgG immune response when transfused into allogeneic recipients. Nitrosylated platelet antigen trafficking within recipient APC was assessed by using adherent macrophages and various inhibitors of processing. When adherent APC were pulsed with nitrosylated platelet antigens in the presence of either Brefeldin A or proteosome inhibitors, IgG anti-platelet immunity against the platelets was restored. Furthermore, the IgG immunity could also be rescued against the nitrsosylated platelets if the recipients were first depleted of CD8+ T cells by injection of a monoclonal antibody. These results suggest that if platelet antigens are nitrosylated within antigen presenting cells, they are preferentially shunted to the MHC class I processing pathway and presented to CD8+ T cells that suppress the IgG immune response. Thus, it appears that reactive oxygen species act as intracellular regulators that determine whether a productive IgG immune response against platelet transfusions will occur.

scholarly journals Microsomal triglyceride transfer protein lipidation and control of CD1d on antigen-presenting cells

2005 ◽  
Vol 202 (4) ◽  
pp. 529-539 ◽  
Author(s):  
Stephanie K. Dougan ◽  
Azucena Salas ◽  
Paul Rava ◽  
Amma Agyemang ◽  
Arthur Kaser ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Microsomal Triglyceride Transfer Protein ◽  
Antigen Presenting Cells ◽  
Human Monocyte ◽  
Lipid Transfer ◽  
Mouse Splenocytes ◽  
Transfer Protein ◽  
Er Chaperone ◽  
Antigen Presenting

Microsomal triglyceride transfer protein (MTP), an endoplasmic reticulum (ER) chaperone that loads lipids onto apolipoprotein B, also regulates CD1d presentation of glycolipid antigens in the liver and intestine. We show MTP RNA and protein in antigen-presenting cells (APCs) by reverse transcription–polymerase chain reaction and by immunoblotting of mouse liver mononuclear cells and mouse and human B cell lines. Functional MTP, demonstrated by specific triglyceride transfer activity, is present in both mouse splenocytes and a CD1d-positive mouse NKT hybridoma. In a novel in vitro transfer assay, purified MTP directly transfers phospholipids, but not triglycerides, to recombinant CD1d. Chemical inhibition of MTP lipid transfer does not affect major histocompatibility complex class II presentation of ovalbumin, but considerably reduces CD1d-mediated presentation of α-galactosylceramide (α-galcer) and endogenous antigens in mouse splenic and bone marrow–derived dendritic cells (DCs), as well as in human APC lines and monocyte-derived DCs. Silencing MTP expression in the human monocyte line U937 affects CD1d function, as shown by diminished presentation of α-galcer. We propose that MTP acts upstream of the saposins and functions as an ER chaperone by loading endogenous lipids onto nascent CD1d. Furthermore, our studies suggest that a small molecule inhibitor could be used to modulate the activity of NKT cells.

scholarly journals 751 Neo-X-Prime bispecific antibodies targeting CD40 and tumor antigens promote cross-presentation of tumor exosome-derived neoantigen and induce superior anti-tumor responses compared to CD40 mAb

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A785-A785
Author(s):  
Karin Hagerbrand ◽  
Mattias Levin ◽  
Laura Von Schantz ◽  
Laura Varas ◽  
Anna Säll ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Antigens ◽  
Antigen Presenting Cells ◽  
Immunological Memory ◽  
Cell Repertoire ◽  
Cross Presentation ◽  
Antigen Presenting

BackgroundAlligator's Neo-X-Prime platform aims to enable antigen presenting cells to efficiently enhance priming of tumor neoantigen-specific T cells with the goal of overcoming PD-1 resistance in certain tumor types. We hypothesize that binding of a CD40 x TAA bispecific antibody (bsAb) to CD40 on dendritic cells (DCs) and a tumor-associated antigen (TAA) on tumor exosomes or tumor debris leads to (i) activation of the DC, (ii) uptake of the tumor material, (iii) cross-presentation of tumor-derived neoantigen (present in exosomes or debris) and, iv) priming of tumor neoantigen-specific T cells, resulting in an increased quantity and/or quality of the tumor-targeting T cell pool.MethodsFunctionality was evaluated in vitro using CD40 reporter cells and monocyte-derived DCs, co-cultured with cells expressing TAA. Further, co-localization of TAA-expressing cellular debris with a CD40-expressing human B cell line in the presence of bsAbs was assessed using live cell imaging. In vivo, anti-tumor efficacy and immunological memory were assessed in human CD40 transgenic (hCD40tg) mice bearing MB49 bladder carcinoma tumors transfected with human TAA or controls. T cells isolated from OVA-specific TCR-transgenic mice were used to evaluate the effect of Neo-X-Prime bsAbs on antigen-specific T cell expansion in the presence of hCD40tg DCs and exosomes from MB49 tumors transfected with both human TAA and OVA using flow cytometry.ResultsUsing CEA as a highly expressed TAA, we have developed lead Neo-X-Prime CD40-CEA bsAbs engineered to achieve an optimal profile. Further, using Neo-X-Prime concept molecules targeting EpCAM, we have demonstrated the ability to mediate co-localization of tumor debris and CD40 expressing antigen presenting cells that is dependent on the receptor density of the TAA. We have further shown that addition of Neo-X-Prime bsAbs to a co-culture of murine DCs, T cells and tumor-derived exosomes induces increased expansion of model neoantigen-specific T cells. In vivo, Neo-X-Prime bsAbs display a potent, TAA-dependent anti-tumor effect that is superior to CD40 mAbs. Cured mice develop a broad immunological memory that is not dependent on expression of the TAA. The tumor-localizing property of Neo-X-Prime bsAbs also shows potential for improved safety compared to CD40 monospecific antibodies.ConclusionsNeo-X-Prime bsAbs have the potential to tumor-selectively target CD40-expressing antigen-presenting cells to mediate an expansion of the tumor-specific T cell repertoire, resulting in increased T cell infiltration and potent anti-tumor effects.Ethics ApprovalAll experiments were performed after approval from the Malmö/Lund Animal Ethics Committee.

scholarly journals Granulysin activates antigen-presenting cells through TLR4 and acts as an immune alarmin

Blood ◽  
2010 ◽  
Vol 116 (18) ◽  
pp. 3465-3474 ◽  
Author(s):  
Poonam Tewary ◽  
De Yang ◽  
Gonzalo de la Rosa ◽  
Yana Li ◽  
Michael W. Finn ◽  
...  
Keyword(s):  
Immune Response ◽  
Nk Cells ◽  
Antigen Presenting Cells ◽  
Antimicrobial Protein ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Endotoxin Contamination ◽  
Antigen Presenting

Abstract Granulysin (GNLY), an antimicrobial protein present in the granules of human cytotoxic T lymphocytes and natural killer (NK) cells, is produced as an intact 15-kDa form that is cleaved to yield a 9-kDa form. Alarmins are endogenous mediators that can induce recruitment and activation of antigen-presenting cells (APCs) and consequently promote the generation of immune response. We hypothesized that GNLY might function as an alarmin. Here, we report that both 9- and 15-kDa forms of recombinant GNLY-induced in vitro chemotaxis and activation of both human and mouse dendritic cells (DCs), recruited inflammatory leucocytes, including APCs in mice, and promoted antigen-specific immune responses upon coadministration with an antigen. GNLY-induced APC recruitment and activation required the presence of Toll-like receptor 4. The observed activity of recombinant GNLY was not due to endotoxin contamination. The capability of the supernatant of GNLY-expressing HuT78 cells to activate DC was blocked by anti-GNLY antibodies. Finally we present evidence that supernatants of degranulated human NK92 or primary NK cells also activated DCs in a GNLY- and Toll-like receptor 4–dependent manner, indicating the physiologic relevance of our findings. Thus, GNLY is the first identified lymphocyte-derived alarmin capable of promoting APC recruitment, activation, and antigen-specific immune response.

Characterization of B-1b cells as antigen presenting cells in the immune response to gp43 from Paracoccidioides brasiliensis in vitro

2002 ◽  
Vol 83 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Ana Flavia Grandi Vigna ◽  
Luiz Claudio Godoy ◽  
Sandro Rogerio de Almeida ◽  
Mario Mariano ◽  
José Daniel Lopes
Keyword(s):  
Immune Response ◽  
Paracoccidioides Brasiliensis ◽  
Antigen Presenting Cells ◽  
Antigen Presenting

scholarly journals Street RABV induces the cholinergic anti-inflammatory pathway in human monocyte-derived macrophages by binding to nAChr ɑ7, and upregulates the M2-c marker CD163

2021 ◽  
Author(s):  
C.W.E. Embregts ◽  
L. Begeman ◽  
C.J. Voesenek ◽  
B.E.E. Martina ◽  
M.P.G. Koopmans ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cell ◽  
Human Monocyte ◽  
T Cell Proliferation ◽  
Strong Immune Response ◽  
Inflammatory Pathway ◽  
Inflammatory State ◽  
The Central Nervous System ◽  
Anti Inflammatory ◽  
Antigen Presenting

AbstractRabies virus (RABV) is able to reach the central nervous system (CNS) without triggering a strong immune response, using multiple mechanisms to evade and suppress the host immune system. After infection via a bite or scratch from a rabid animal, RABV comes into contact with macrophages, which are the first antigen-presenting cells (APCs) that are recruited to the area and play an essential role in the onset of a specific immune response. It is poorly understood how RABV affects macrophages, and if the interaction contributes to the observed immune suppression. This study was undertaken to characterize the interactions between RABV and human monocyte-derived macrophages (MDMs). We showed that street RABV does not replicate in human MDMs. Using a recombinant trimeric RABV glycoprotein (RABV-tG) we showed binding to the nicotinic acetylcholine receptor alpha 7 (nAChr ɑ7) on MDMs, and confirmed the specificity using the nAChr ɑ7 antagonist alpha-bungarotoxin (ɑ-BTX). We found that this binding induced the cholinergic anti-inflammatory pathway (CAP), characterized by a significant decrease in tumor necrosis factor ɑ (TNF-ɑ) upon LPS challenge. Using confocal microscopy we found that induction of the CAP is associated with significant cytoplasmic retention of nuclear factor κB (NF-κB). Co-cultures of human MDMs exposed to street RABV and autologous T cells further revealed that the observed suppression of MDMs affects their function as T cell activators as well, as we found a significant decrease in proliferation of CD8+ T cells. Lastly, using flow cytometric analysis we observed a significant increase in expression of CD163, hinting that street RABV is able to polarize macrophages towards a M2-c anti-inflammatory phenotype. Taken together, these results show that street RABV is capable of inducing an anti-inflammatory state in human macrophages, which affects T cell proliferation.Author summaryRabies virus (RABV) is transmitted by a bite or a scratch from an infected animal. Infection leads to a lethal encephalitis and once clinical symptoms occur, there is no effective treatment available. The virus is able to travel from the initial site of infection to the central nervous system without triggering a strong immune response, using multiple mechanisms to evade and suppress the immune system. Up to present it is unclear when and where this immunosuppression is initiated, and if local immune cells are involved as well. Understanding the complete mechanisms of immunosuppression by RABV is essential for the development and improvement of effective post-exposure treatments. In this paper we studied if RABV is able to suppress human primary macrophages as these will be the first antigen-presenting cells that are recruited to the site of infection, and are known to be important in initiating an efficient immune response. We show that RABV is able to bind, but not infect, human macrophages. Binding induces an anti-inflammatory pathway, which leads to limited T cell proliferation and directs macrophages towards and anti-inflammatory state. These results show that RABV-macrophage interactions might indeed be one of the early steps in the onset of RABV-induced immunosuppression.

scholarly journals Eosinophils Can Function as Antigen-Presenting Cells To Induce Primary and Secondary Immune Responses to Strongyloides stercoralis

2006 ◽  
Vol 74 (6) ◽  
pp. 3232-3238 ◽  
Author(s):  
Udaikumar M. Padigel ◽  
James J. Lee ◽  
Thomas J. Nolan ◽  
Gerhard A. Schad ◽  
David Abraham
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Immune Responses ◽  
Mhc Class Ii ◽  
Antigen Presenting Cells ◽  
Strongyloides Stercoralis ◽  
Th2 Cells ◽  
Cells In Culture ◽  
Antigen Presenting

ABSTRACT Several studies have demonstrated roles for eosinophils during innate and adaptive immune responses to helminth infections. However, evidence that eosinophils are capable of initiating an immune response to parasite antigens is lacking. The goal of the present in vitro study was to investigate the potential of eosinophils to serve as antigen-presenting cells (APC) and initiate an immune response to parasite antigens. Purified eosinophils were exposed to soluble Strongyloides stercoralis antigens, and the expression of various surface markers involved in cell activation was examined. Antigen-exposed eosinophils showed a sixfold increase in expression levels of CD69 and major histocompatibility complex (MHC) class II, a fourfold increase in levels of T-cell costimulatory molecule CD86, and a twofold decrease in levels of CD62L compared to eosinophils cultured in medium containing granulocyte-macrophage colony-stimulating factor. The ability of eosinophils to present antigen to T cells was determined by culturing them with T cells in vitro. Eosinophils pulsed with antigen stimulated antigen-specific primed T cells and CD4+ T cells to increase interleukin-5 (IL-5) production. The blocking of MHC class II expression on eosinophils inhibited their ability to induce IL-5 production by CD4+ T cells in culture. Antigen-pulsed eosinophils were able to prime naïve T cells and CD4+ T cells in culture and polarized them into Th2 cells producing IL-5 similar to that induced by antigen-loaded dendritic cells. These results demonstrate that eosinophils are capable of activating antigen-specific Th2 cells inducing the release of cytokines and assist in the priming of naïve T cells to initiate Th2 responses against infection. This study highlights the potential of eosinophils to actively induce immune responses against infection by amplifying antigen-specific Th2-cell responses.

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