Expression and regulation of Schlafen (SLFN) family members in primary human monocytes, monocyte-derived dendritic cells and T cells

Abstract Oral tolerance is a key feature of intestinal immunity, generating systemic tolerance to fed antigens. However, the molecular mechanism mediating oral tolerance remains unclear. In this study, we examined the role of the B7 family members of costimulatory molecules in the establishment of oral tolerance. Deficiencies of B7-H1 and B7-DC abrogated the oral tolerance, accompanied by enhanced antigen-specific CD4+ T-cell response and IgG1 production. Mesenteric lymph node (MLN) dendritic cells (DCs) displayed higher levels of B7-H1 and B7-DC than systemic DCs, whereas they showed similar levels of CD80, CD86, and B7-H2. MLN DCs enhanced the antigen-specific generation of CD4+Foxp3+ inducible regulatory T cells (iTregs) from CD4+Foxp3− T cells rather than CD4+ effector T cells (Teff) relative to systemic DCs, owing to the dominant expression of B7-H1 and B7-DC. Furthermore, the antigen-specific conversion of CD4+Foxp3− T cells into CD4+Foxp3+ iTregs occurred in MLNs greater than in peripheral organs during oral tolerance under steady-state conditions, and such conversion required B7-H1 and B7-DC more than other B7 family members, whereas it was severely impaired under inflammatory conditions. In conclusion, our findings suggest that B7-H1 and B7-DC expressed on MLN DCs are essential for establishing oral tolerance through the de novo generation of antigen-specific CD4+Foxp3+ iTregs.

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Abstract 069: Isoketals in Monocyte-Derived Dendritic Cells Activate T Cells and Promote Hypertension

Hypertension ◽

10.1161/hyp.64.suppl_1.069 ◽

2014 ◽

Vol 64 (suppl_1) ◽

Author(s):

Roxana Loperena ◽

Annet Kirabo ◽

Sean S Davies ◽

LJ Roberts ◽

David G Harrison

Keyword(s):

T Cells ◽

Endothelial Cells ◽

Dendritic Cells ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Oxidant Stress ◽

Fold Increase ◽

Human Monocytes ◽

Pre Treatment

Fatty acid oxidation leads to formation of highly reactive γ-ketoaldehydes termed isoketals that adduct to protein lysines. We have shown that hypertension causes isoketals to accumulate in dendritic cells (DCs) and activate T cells. Human monocytes traversing the endothelium differentiate into DCs expressing CD83, MHC-II, and CD11c. We hypothesized that oxidative stress catalyzes the formation of isoketals which alters monocyte and DC function to promote monocyte transformation to DCs and T cell activation. Thus, we co-cultured human monocytes with aortic endothelial cells exposed to either a hypertensive 10% stretch or a normotensive 5% stretch for 48 hours using the Uniflex® culture system. We used flow cytometry to detect human DC markers (CD14-/CD83+) in monocytes exposed to stretch. We detected conversion of CD14-/CD83+ from CD14+ human monocytes and found they contained increased levels of isoketal-ligated proteins in the 10% compared to 5% stretch (77.47 ± 7.3 vs. 12.14 ± 3.5). We also found a 1.8 fold increase of the CD86 activation marker compared to controls. Exposure of murine monocyte-derived DCs to tert-butyl hydroperoxide (t-BHP) led to a 3-fold increase in isoketals and a 2-fold increase in CD86 in the CD11b+/CD11c+ population compared to controls. Isoketal formation in DCs exposed to t-BHP was scavenged with pre-treatment of 2-hydroxybenzylamine (2-HOBA) in vitro. DCs treated with t-BHP were co-cultured with T cells for 7 days. This promoted T cell survival and proliferation of CD8+ and CD4+ T cells compared to untreated controls; this effect was attenuated with pre-treatment of 2-HOBA. Moreover, adoptive transfer of t-BHP treated DCs to normal mice elevated the hypertensive response to a generally subpressor dose of angiotensin-II (128 ± 0.80 vs. 114 ± 0.48 in controls). We conclude that oxidant stress and isoketal formation in murine DCs promote T cell activation and hypertension. We hypothesize that exposure to hypertensive stretch in human endothelial cells transfers an oxidant signal to monocytes and promotes their transformation to DCs, which mature and promote an immune response. These findings provide a mechanism as to how T cells are activated in hypertension and provide insight into the inflammatory nature of this disease.

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Mycobacteria Exploit p38 Signaling To Affect CD1 Expression and Lipid Antigen Presentation by Human Dendritic Cells

Infection and Immunity ◽

10.1128/iai.00607-09 ◽

2009 ◽

Vol 77 (11) ◽

pp. 4947-4952 ◽

Cited By ~ 20

Author(s):

Maria Cristina Gagliardi ◽

Raffaela Teloni ◽

Federico Giannoni ◽

Sabrina Mariotti ◽

Maria Elena Remoli ◽

...

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Lymphocytes ◽

Mitogen Activated Protein Kinase ◽

Immune Recognition ◽

Human Monocytes ◽

Membrane Expression ◽

Lipid Antigens ◽

Group I ◽

Antigen Presenting

ABSTRACT Group I CD1 proteins are specialized antigen-presenting molecules that present both microbial and self lipid antigens to CD1-restricted α/β T lymphocytes. The production of high levels of gamma interferon and lysis of infected macrophages by lipid-specific T lymphocytes are believed to play pivotal roles mainly in the defense against mycobacterial infections. We previously demonstrated that Mycobacterium tuberculosis and bacillus Calmette-Guérin (Mycobacterium bovis BCG) induce human monocytes to differentiate into CD1− dendritic cells (DC), which cannot present lipid antigens to specific T cells. Here, we show that in human monocytes mycobacteria trigger phosphorylation of p38 mitogen-activated protein kinase to inhibit CD1 expression in DC derived from infected monocytes. Pretreatment with a specific p38 inhibitor renders monocytes insensitive to mycobacterial subversion and allows them to differentiate into CD1+ DC, which are fully capable of presenting lipid antigens to specific T cells. We also report that one of the pathogen recognition receptors triggered by BCG to activate p38 is complement receptor 3 (CR3), as shown by reduced p38 phosphorylation and partial reestablishment of CD1 membrane expression obtained by CR3 blockade before infection. In conclusion, we propose that p38 signaling is a novel pathway exploited by mycobacteria to affect the expression of CD1 antigen-presenting cells and avoid immune recognition.

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Dendritic Cells Promoted by Ginseng Saponins Drive a Potent Th1 Polarization

Biomarker Insights ◽

10.4137/bmi.s585 ◽

2008 ◽

Vol 3 ◽

pp. BMI.S585 ◽

Cited By ~ 10

Author(s):

Masao Takei ◽

Eiichi Tachikawa ◽

Akemi Umeyama

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Cell ◽

Immune Responses ◽

Cell Polarization ◽

Th1 Cells ◽

Human Monocytes ◽

Ifn Γ ◽

Pharmacologically Active ◽

Dc Maturation

Dendritic cells (DC) play a pivotal role in the initiation of T-cell-mediated immune responses, making them an attractive cellular adjuvant for use in cancer vaccines. The interaction of T cells with DC is crucial for directing T cell differentiation towards the Th1, Th2 or Th17 type, and several factors determining the direction of the T cell polarization. IL-12 plays a central role in the immune system, not only by augmenting the cytotoxic activity of T cells and NK cells and regulating IFN-γ production, but also by the capacity of IL-12 to promote the development of Th1 cells. Therefore, it is important to identify factors that might affect the differentiation, maturation and function of DC. Ginseng is a medicinal herb widely used in Asian countries, and many of its pharmacological actions are attributed to the ginsenosides. Moreover, T-cadinol and calamenene are sesquterpenes isolated from the heartwood of Cryptomeria japonica being pharmacologically active substances. We investigated whether M1 and M4, end products of steroidal ginseng saponins metabolized in digestive tracts, as well as T-cadinol and calamenene can drive DC maturation from human monocytes in vitro. Human monocytes were cultured with GM-CSF and IL-4 for 6 days under standard conditions, followed by another 2 days in the presence of M1, M4, T-cadinol or calamenene. The expression levels of CD1a, CD80, CD83, CD86 and HLA-DR on M1-primed DC, M4-primed DC, T-cadinol-primed DC and calamenene-primed DC were enhanced with a concomitant decrease in endocytic activity. M1-primed DC, M4-primed DC, T-cadinol-primed DC or calamenene-primed DC enhanced the T cell stimulatory capacity in an allo MLR (allogeneic mixed lymphocyte reaction). Naïve T cells co-cultured with allogeneic M1-primed DC, M4-primed DC, T-cadinol-primed DC or calamenene-primed DC turned into typical Th1 cells, which produced large quantities of IFN-γ and released small amounts of IL-4 depending on IL-12 secretion. In the CTL assay (cytotoxic T-lymphocyte assay), the production of IFN-γ and 51Cr release on M4-primed DC was more augmented than of immature DC or TNF-α-primed DC. These results suggest that M1, M4, T-cadinol and calamenene appear to be a good factor to induce DC maturation, or even better in some respect, for the use in clinical DC therapy to induce strong Th1 type immune responses.

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