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.

Cytotoxic Effects of CML28 Specific T Cells on Acute Leukemia Cells In Vitro.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4886-4886
Author(s):  
Hanwen Mao ◽  
Wenli Liu ◽  
Zhe Gen ◽  
Wei Huang ◽  
Yicheng Zhang ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Leukemia ◽  
Mononuclear Cells ◽  
Antigen Presenting Cells ◽  
Leukemia Cells ◽  
Cytotoxic Effects ◽  
Artificial Antigen ◽  
Leukemia Treatment ◽  
Antigen Presenting

Abstract The antigen-specific cytotoxic T lymphocyte activated by antigen presenting cell is widely used in cell immunotherapy recently. CML28, which was screened from chronic myelogenous leukemia (CML) patients, was reported to be a specific tumour antigen and over-expressed on CML cells and acute leukemia cells. Therefore, CML28 could be a potential target for leukemia treatment. Dendritic cells (DC) are the most important antigen present cells, but it is hard to isolate and culture DCs for clinical use, which hampers the specific cell immunotherapy. Our investigation aimed to study the cytotoxic effects of CML28 specific T cells activated by artificial antigen presenting cells, on acute leukemia cells in vitro. Artificial antigen presenting cells were prepared by connecting CML28 to magnetic superbead that containing HLA-A2-Ig and B7-1 molecule. Mononuclear cells were isolated from the bone marrow or peripheral blood of healthy donors with positive HLA-A2. The artificial antigen-presenting cells were co-cultured with isolated mononuclear cells for four weeks. The activation and proliferation of CML28-specific T cells were measured by dimmer binding technique using flow cytometry. The cytotoxic effects of CML28-specific T cells on leukemia cells, which were isolated from leukemia patient, were evaluated by lactate dehydrogenase (LDH) releasing assay. Increased proportion of CML28-specific T cells was observed in artificial antigen-presenting group than in control group (29.27±3.54% vs 2.95±0.66%, p<0.05). For cytotoxic effects assay, significant higher killing efficiency was seen in artificial antigen-presenting group (41.47±4.23%vs3.56±0.71%, when the effector: target ration is 40:1, p<0.01). Therefore, we concluded that the artificial antigen presenting cells could mimic antigen presenting cells to induce specific T cell activation and proliferation, and cytotoxic effects on target cells, indicating that artificial antigen presenting cell-induced cytotocix T cells could be an option for leukemia treatment.

Abstract MP38: High Salt Activates The NLRP3 Inflammasome In Antigen Presenting Cells Via ENaC To Promote Salt-Sensitive Hypertension

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Ashley L Pitzer ◽  
Natalia R Barbaro ◽  
Luul Aden ◽  
Evan C Ray ◽  
Thomas R Kleyman ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Culture Media ◽  
Antigen Presenting Cells ◽  
High Salt ◽  
Inflammasome Activation ◽  
Cvd Risk ◽  
Mouse Splenocytes ◽  
Antigen Presenting ◽  
Salt Sensitive Hypertension

Salt-sensitivity is a major risk factor for hypertension and cardiovascular disease (CVD). Reducing dietary Na + decreases blood pressure and CVD risk. However, the precise mechanisms of how Na + leads to hypertension are still not well defined. Recently, we found that dendritic cells (DCs) in response to increases in extracellular [Na + ] exhibit an amiloride-sensitive epithelial Na + channel (ENaC)-dependent activation of NADPH-oxidase, superoxide production, reactive isolevuglandin (IsoLG)-protein adduct formation, and cytokine secretion which promote hypertension. We hypothesized that the NLRP3 inflammasome in antigen-presenting cells (APCs) mediates salt-sensitive hypertension through an ENaC-dependent mechanism. To test this hypothesis, we cultured mouse splenocytes in normal-salt or high-salt (HS) media with or without co-treatment with the ENaC inhibitor, amiloride (20 μM). Using flow cytometry, we found that HS increased monocyte and DC IL-1β production, which was confirmed through an ELISA assay detecting IL-1β release (2.131 ± 0.733 vs 12.75 ± 1.108 pg/mL, p<0.01) into the culture media, and amiloride treatment prevented IL-1β production (12.75 ± 1.108 vs 1.905 ± 0.3495 pg/mL, p<0.01) in these cells. To confirm our in vitro data, we treated salt-sensitive mice on a 129-SvJ background with a HS diet (4% NaCl) for 28 days with or without amiloride (1mg/kg/day in drinking water) or NLRP3 inflammasome inhibitor MCC950 (10mg/kg i.p.). Amiloride or MCC950 treated mice developed blunted hypertension in response to HS (120.4 ± 2.99; 101.0 ± 3.74) compared to vehicle controls (140.5 ± 3.98). Amiloride treated mice also exhibited less expression of NLRP3, pro-IL1β, and IsoLGs in DCs and monocytes compared to controls. Interestingly, MCC950 treated mice exhibited decreased pro-IL1β but not NLRP3 expression or IsoLG production. Using the DOCA-salt model, we found similar increases in NLRP3, pro-IL1β, and IsoLGs expression in DCs and monocytes, which was abolished after treatment with IsoLG scavenger 2-HOBA (1g/L). Our findings suggest a role for ENaC-dependent NLRP3 inflammasome activation in APCs in response to a HS diet, which may represent a promising treatment approach to salt-induced hypertension.

scholarly journals MTP regulated by an alternate promoter is essential for NKT cell development

2007 ◽  
Vol 204 (3) ◽  
pp. 533-545 ◽  
Author(s):  
Stephanie K. Dougan ◽  
Paul Rava ◽  
M. Mahmood Hussain ◽  
Richard S. Blumberg
Keyword(s):  
Lipid Transfer Protein ◽  
Microsomal Triglyceride Transfer Protein ◽  
Cell Development ◽  
Northern Analysis ◽  
Lipid Transfer ◽  
Nkt Cell ◽  
Transfer Protein ◽  
Phospholipid Transfer ◽  
Apob Secretion

Microsomal triglyceride transfer protein (MTP), an endoplasmic reticulum lipid transfer protein critical for apolipoprotein B (apoB) secretion, regulates CD1d antigen presentation. We identified MTP variant 1 (MTPv1), a novel splice variant of mouse MTP, by polymerase chain reaction and Northern analysis in non–apoB-secreting tissues, including thymocytes and antigen-presenting cells (APCs). Edman degradation of MTPv1 isolated from transfected cells revealed three unique residues; however, recombinant MTP and MTPv1 had an equivalent protein disulfide isomerase association, subcellular localization, triglyceride transfer, phospholipid transfer, response to inhibitors, and ability to support apoB secretion. MTP and MTPv1 efficiently transferred phosphatidylethanolamine to CD1d in vitro. NKT cells fail to develop in fetal thymic organ culture (FTOC) treated with MTP antagonists. MTP-inhibited FTOCs produced negligible numbers of CD1d tetramer–positive cells and exhibited marked defects in IL-4 production upon stimulation with anti-CD3 or α-galactosylceramide–pulsed APCs. CD1d expression on CD4+CD8+ FTOC cells was unaffected by MTP inhibition. Thus, our results demonstrate that MTPv1 in thymocytes is critical to NKT cell development. We hypothesize that, when MTP is inactive, CD1d traffics to the cell surface and presents no lipid or a lipid that is incapable of mediating NKT cell selection and/or is refractory to lysosomal editing.

scholarly journals A distal effect of microsomal triglyceride transfer protein deficiency on the lysosomal recycling of CD1d

2007 ◽  
Vol 204 (4) ◽  
pp. 921-928 ◽  
Author(s):  
Yuval Sagiv ◽  
Li Bai ◽  
Datsen G. Wei ◽  
Reuven Agami ◽  
Paul B. Savage ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Lipid Transfer Protein ◽  
Microsomal Triglyceride Transfer Protein ◽  
Lipid Transfer ◽  
Mhc I ◽  
Transfer Protein ◽  
Lipid Antigen ◽  
Lipid Presentation ◽  
Antigen Presenting ◽  
Lipid Loading

Microsomal triglyceride transfer protein (MTP) is an endoplasmic reticulum (ER)–resident lipid transfer protein involved in the biosynthesis and lipid loading of apolipoprotein B. MTP was recently suggested to directly regulate the biosynthesis of the MHC I–like, lipid antigen presenting molecule CD1d, based on coprecipitation experiments and lipid loading assays. However, we found that the major impact of MTP deficiency occurred distal to the ER and Golgi compartments. Thus, although the rates of CD1d biosynthesis, glycosylation maturation, and internalization from the cell surface were preserved, the late but essential stage of recycling from lysosome to plasma membrane was profoundly impaired. Likewise, functional experiments indicated defects of CD1d-mediated lipid presentation in the lysosome but not in the secretory pathway. These intriguing findings suggest a novel, unexpected role of MTP at a late stage of CD1d trafficking in the lysosomal compartment.

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 Development of Stable Chimeric IL-15 for Trans-Presentation by the Antigen Presenting Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Manoj Patidar ◽  
Naveen Yadav ◽  
Sarat K. Dalai
Keyword(s):  
T Cells ◽  
T Cell ◽  
Half Life ◽  
Therapeutic Potential ◽  
Chimeric Protein ◽  
Antigen Presenting Cells ◽  
T Cell Response ◽  
Antigen Presenting

IL-15 is one of the important biologics considered for vaccine adjuvant and treatment of cancer. However, a short half-life and poor bioavailability limit its therapeutic potential. Herein, we have structured IL-15 into a chimeric protein to improve its half-life enabling greater bioavailability for longer periods. We have covalently linked IL-15 with IgG2 base to make the IL-15 a stable chimeric protein, which also increased its serum half-life by 40 fold. The dimeric structure of this kind of IgG based biologics has greater stability, resistance to proteolytic cleavage, and less frequent dosing schedule with minimum dosage for achieving the desired response compared to that of their monomeric forms. The structured chimeric IL-15 naturally forms a dimer, and retains its affinity for binding to its receptor, IL-15Rβ. Moreover, with the focused action of the structured chimeric IL-15, antigen-presenting cells (APC) would transpresent chimeric IL-15 along with antigen to the T cell, that will help the generation of quantitatively and qualitatively better antigen-specific memory T cells. In vitro and in vivo studies demonstrate the biological activity of chimeric IL-15 with respect to its ability to induce IL-15 signaling and modulating CD8+ T cell response in favor of memory generation. Thus, a longer half-life, dimeric nature, and anticipated focused transpresentation by APCs to the T cells will make chimeric IL-15 a super-agonist for memory CD8+ T cell responses.

scholarly journals The Medicago truncatula N5 Gene Encoding a Root-Specific Lipid Transfer Protein Is Required for the Symbiotic Interaction with Sinorhizobium meliloti

2009 ◽  
Vol 22 (12) ◽  
pp. 1577-1587 ◽  
Author(s):  
Youry Pii ◽  
Alessandra Astegno ◽  
Elisa Peroni ◽  
Massimo Zaccardelli ◽  
Tiziana Pandolfini ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Lipid Transfer Protein ◽  
Symbiotic Association ◽  
Lipid Transfer ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Transfer Protein ◽  
Small Proteins

The Medicago truncatula N5 gene is induced in roots after Sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (LTP), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. Various biological roles for plant LTP in vivo have been proposed, including defense against pathogens and modulation of plant development. The aim of this study was to shed light on the role of MtN5 in the symbiotic interaction between M. truncatula and S. meliloti. MtN5 cDNA was cloned and the mature MtN5 protein expressed in Escherichia coli. The lipid binding capacity and antimicrobial activity of the recombinant MtN5 protein were tested in vitro. MtN5 showed the capacity to bind lysophospholipids and to inhibit M. truncatula pathogens and symbiont growth in vitro. Furthermore, MtN5 was upregulated in roots after infection with either the fungal pathogen Fusarium semitectum or the symbiont S. meliloti. Upon S. meliloti infection, MtN5 was induced starting from 1 day after inoculation (dpi). It reached the highest concentration at 3 dpi and it was localized in the mature nodules. MtN5-silenced roots were impaired in nodulation, showing a 50% of reduction in the number of nodules compared with control roots. On the other hand, transgenic roots overexpressing MtN5 developed threefold more nodules with respect to control roots. Here, we demonstrate that MtN5 possesses biochemical features typical of LTP and that it is required for the successful symbiotic association between M. truncatula and S. meliloti.

Abstract 319: Dalcetrapib-Mediated Modulation of Cholesteryl Ester Transfer Protein Activity Increases HDL-Cholesterol, Apolipoprotein A-I Levels and Cholesterol Efflux Capacity in Chow-Fed Rabbits

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Mathieu R Brodeur ◽  
David Rhainds ◽  
Daniel Charpentier ◽  
Téodora Mihalache-Avram ◽  
Cyrille Maugeais ◽  
...  
Keyword(s):  
Cholesteryl Ester ◽  
Cholesteryl Ester Transfer Protein ◽  
Cholesterol Efflux ◽  
Hdl Cholesterol ◽  
Lipid Transfer ◽  
Protein Activity ◽  
Cholesterol Efflux Capacity ◽  
Transfer Protein

Introduction: A potential approach to reduce CV risk is to increase HDL-C levels. This could be achieved by reducing cholesteryl ester transfer protein (CETP) activity. Dalcetrapib, which modulates CETP activity by changing its conformation and raises HDL-C without inhibiting CETP-induced pre-β-HDL formation in humans, was shown to decrease progression of atherosclerosis in rabbits. Hypothesis: Investigate the modifications of HDL particle size distribution and cholesterol efflux capacity of serum produced by dalcetrapib in normocholesterolemic rabbits. Methods: New Zealand white rabbits were treated with dalcetrapib (300 mg/kg as food admix) or placebo for 14 days. We evaluated CETP conformation and mass by ELISAs (including antibodies sensitive to conformational change), CETP activity by fluorescent lipid transfer, lipid profile and apoA-I distribution in HDL subclasses by 2D-non denaturing gradient gels (2D-NDGGE). Cholesterol efflux capacity of rabbit sera was determined after loading cells with 3 H-free cholesterol, using HepG2 hepatocytes to measure SR-BI-dependent efflux and by inducing ABCA1 or ABCG1 expression in BHK cells. Results: Dalcetrapib modified the conformation of rabbit CETP in vitro and in vivo and, after 14 days, this was associated with increased CETP mass (+50%, p<0.001) and reduced CETP activity (-86%, p<0.001). Total cholesterol was increased with dalcetrapib (+178%, p<0.001), due to a higher HDL-C level. In contrast, dalcetrapib reduced LDL-C and triglycerides by 41% (p<0.01) and 48% (p<0.001). Serum analysis by 2D-NDGGE showed that total rabbit apoA-I was increased 1.7- fold in animals treated with dalcetrapib. This was associated with an increase in large HDL but also in small α-migrating HDL with pre-β-HDL size. Cholesterol efflux assays showed that ABCA1-, ABCG1- and SR-BI-dependent efflux were all increased in dalcetrapib-treated rabbits (+24%, p=0.038; +21%, p=0.021; +44%, p<0.001). Conclusion: Modulation of CETP activity and conformation by dalcetrapib increases HDL-C and apoA-I levels and affects apoA-I distribution in HDL subclasses. These changes are associated with increased cholesterol efflux capacity, suggesting that HDL functionality is preserved in dalcetrapib-treated chow-fed rabbits.

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