Oxidative modification enhances the immunostimulatory effects of extracellular mitochondrial DNA on plasmacytoid dendritic cells

Inflammation is associated with oxidative stress and characterized by elevated levels of damage-associated molecular pattern (DAMP) molecules released from injured or even living cells into the surrounding microenvironment. One of these endogenous danger signals is the extracellular mitochondrial DNA (mtDNA) containing evolutionary conserved unmethylated CpG repeats. Increased levels of reactive oxygen species (ROS) generated by recruited inflammatory cells modify mtDNA oxidatively resulting primarily in accumulation of 8-oxo-7,8-dihydroguanine (8-oxoG) lesions. In this study, we examined the impact of native and oxidatively modified mtDNAs on the phenotypic and functional properties of plasmacytoid dendritic cells (pDCs), which possess a fundamental role in the regulation of inflammation and T cell immunity. Treatment of human primary pDCs with native mtDNA up-regulated the expression of a co-stimulatory molecule (CD86), a specific maturation marker (CD83), and a main antigen-presenting molecule (HLA-DQ) on the cell surface, as well as increased TNF-α and IL-8 production from the cells. These effects were more apparent when pDCs were exposed to oxidatively modified mtDNA. Neither native nor oxidized mtDNA molecules were able to induce interferon (IFN)-α secretion from pDCs unless they formed a complex with human cathelicidin LL-37, an antimicrobial peptide. Interestingly, simultaneous administration of a Toll-like receptor (TLR)9 antagonist abrogated the effects of both native and oxidized mtDNAs on human pDCs. In a murine model, oxidized mtDNA also proved a more potent activator of pDCs compared to the native form, except for induction of IFN-α production. Collectively, we demonstrate here for the first time that elevated levels of 8-oxoG bases in the extracellular mtDNA induced by oxidative stress increase the immunostimulatory capacity of mtDNA on pDCs

PPARγ controls CD1d expression by turning on retinoic acid synthesis in developing human dendritic cells

Dendritic cells (DCs) expressing CD1d, a molecule responsible for lipid antigen presentation, are capable of enhancing natural killer T (iNKT) cell proliferation. The signals controlling CD1 expression and lipid antigen presentation are poorly defined. We have shown previously that stimulation of the lipid-activated transcription factor, peroxisome proliferator-activated receptor (PPAR)γ, indirectly regulates CD1d expression. Here we demonstrate that PPARγ, turns on retinoic acid synthesis by inducing the expression of retinol and retinal metabolizing enzymes such as retinol dehydrogenase 10 and retinaldehyde dehydrogenase type 2 (RALDH2). PPARγ-regulated expression of these enzymes leads to an increase in the intracellular generation of all-trans retinoic acid (ATRA) from retinol. ATRA regulates gene expression via the activation of the retinoic acid receptor (RAR)α in human DCs, and RARα acutely regulates CD1d expression. The retinoic acid–induced elevated expression of CD1d is coupled to enhanced iNKT cell activation. Furthermore, in vivo relevant lipids such as oxidized low-density lipoprotein can also elicit retinoid signaling leading to CD1d up-regulation. These data show that regulation of retinoid metabolism and signaling is part of the PPARγ-controlled transcriptional events in DCs. The uncovered mechanisms allow the DCs to respond to altered lipid homeostasis by changing CD1 gene expression

DC-ATLAS: a systems biology resource to dissect receptor specific signal transduction in dendritic cells

BACKGROUND: The advent of Systems Biology has been accompanied by the blooming of pathway databases. Currently pathways are defined generically with respect to the organ or cell type where a reaction takes place. The cell type specificity of the reactions is the foundation of immunological research, and capturing this specificity is of paramount importance when using pathway-based analyses to decipher complex immunological datasets. Here, we present DC-ATLAS, a novel and versatile resource for the interpretation of high-throughput data generated perturbing the signaling network of dendritic cells (DCs). RESULTS: Pathways are annotated using a novel data model, the Biological Connection Markup Language (BCML), a SBGN-compliant data format developed to store the large amount of information collected. The application of DC-ATLAS to pathway-based analysis of the transcriptional program of DCs stimulated with agonists of the toll-like receptor family allows an integrated description of the flow of information from the cellular sensors to the functional outcome, capturing the temporal series of activation events by grouping sets of reactions that occur at different time points in well-defined functional modules. CONCLUSIONS: The initiative significantly improves our understanding of DC biology and regulatory networks. Developing a systems biology approach for immune system holds the promise of translating knowledge on the immune system into more successful immunotherapy strategies

Gut Microbiota Species Can Provoke both Inflammatory and Tolerogenic Immune Responses in Human Dendritic Cells Mediated by Retinoic Acid Receptor Alpha Ligation

La implementación de la estrategia del marketing directo construida sobre las ecuaciones estructurales permitirán garantizar que el potencial cliente se convierta en un cliente cautivo; este cambio es ilustrado por el modelo de Gemma Muñoz & Elósegui (2012), en el cual se precisan cuatro etapas, desde la captación hasta la retención; en la presente investigación se ha considerado en los objetivos cada etapa; además en cada una se han definido los indicadores de gestión, los cuales definen, a la vez, la información que permitirá conocer el avance en términos de preferencias. La investigación es cuantitativa, descriptiva y tecnológica; su diseño es cuasi experimental, con un muestreo no probabilístico, cuya muestra ha sido determinada por conveniencia, conformada por los potenciales clientes de la Escuela Profesional de Ingeniería de Sistemas y de los programas. Los resultados de la investigación indican que la estrategia emocional de Neuromarketing directo 3.0 mejoró el tiempo de búsqueda de páginas por sesión, en un 26.001%; además el valor de p=0,000 fue significativo, porque es menor al nivel de significancia, quedando comprobada la hipótesis específica. Así mismo, se demostró que esta estrategia emocional de NeuroMarketing directo 3.0 mejoró en un 36.25% la conversión de usuarios potenciales de las carreras de la Universidad Peruana Unión, cuyo valor de p=0,061, menor al nivel de significancia del 0.05, confirma la aprobación de la segunda hipótesis específica. Además, se demostró que estas estrategias de Neuromarketing mejoraron la cantidad de visitas que corresponde a otro objetivo, en un 46.43%, cuyo valor de P=0,000, menor al nivel de significancia 5%, confirma la prueba de la tercera hipótesis específica.TesisT02317TA 4 S23 201

Signaling Lymphocyte Activation Molecule Family 5 Enhances Autophagy and Fine-Tunes Cytokine Response in Monocyte-Derived Dendritic Cells via Stabilization of Interferon Regulatory Factor 8

Signaling lymphocyte activation molecule family (SLAMF) receptors are essential regulators of innate and adaptive immune responses. The function of SLAMF5/CD84, a family member with almost ubiquitous expression within the hematopoietic lineage is poorly defined. In this article, we provide evidence that in human monocyte-derived dendritic cells (moDCs) SLAMF5 increases autophagy, a degradative pathway, which is highly active in dendritic cells (DCs) and plays a critical role in orchestration of the immune response. While investigating the underlying mechanism, we found that SLAMF5 inhibited proteolytic degradation of interferon regulatory factor 8 (IRF8) a master regulator of the autophagy process by a mechanism dependent on the E3-ubiquitin ligase tripartite motif-containing protein 21 (TRIM21). Furthermore, we demonstrate that SLAMF5 influences the ratio of CD1a+ cells in differentiating DCs and partakes in the regulation of IL-1β, IL-23, and IL-12 production in LPS/IFNγ-activated moDCs in a manner that is consistent with its effect on IRF8 stability. In summary, our experiments identified SLAMF5 as a novel cell surface receptor modulator of autophagy and revealed an unexpected link between the SLAMF and IRF8 signaling pathways, both implicated in multiple human pathologies

Effect of sigmar-1 gene silencing on the DMT-modified cytokine profile of LPS or polyI:C-activated moDCs.

<p><b>A:</b> Validation of siRNA knockdown by Western blot. MoDCs were transfected with negative control siRNA (ctrl siRNA) or with gene-targeting siRNA (sigmar-1 siRNA), or left untreated (non-transfected, NT). <b>B–C:</b> Non-treated, 24 h ctrl siRNA-only, and 24 h targeting siRNA-only treated cells were used as negative controls (black bars). Red bars represent 24 h 500 ng/ml LPS-treated cells, while white bars show ctrl siRNA and 1 h DMT pre-treated cells activated with LPS for one day. Grey (NN-DMT) and checkered bars (5-MeO-DMT) demonstrate 1 h DMT pre-treated and then 24 h LPS activated sigmar-1 knockdown cells. <b>D–E:</b> MoDCs were treated as in Fig5B–C. Here, cell activation was performed with a 24 h 20 µg/ml polyI:C treatment. Blue bars represent polyI:C-only stimulation as positive control. Results are shown as Mean ± SEM of three independent donors. (*) represents <i>p</i> values <0.05. Differences are significant (<i>p</i><0.05) in all cases of specific activation (LPS or polyI:C) versus control cells (no treatment, ctrl siRNA, sigmar-1 siRNA).</p

NN-DMT and 5-MeO-DMT pre-treatment of pathogen-activated human dendritic cells effectively inhibit their capacity to prime autologous naive T helper 1 and T helper 17 cells.

<p>Dendritic cells were activated either by heat-killed <i>E. coli</i> (E. coli) or inactivated influenza virus (IV) for 24 h, washed, and then co-cultured with naive autologous CD4⁺ T lymphocytes for 4 days. The number of primed, IFNγ or IL-17 secreting T cells was assessed by ELISPOT assay. T cells alone (T-cell ctrl), and non-activated DCs treated with DMT and co-cultured with autologous naive CD4⁺ T lymphocytes (NN-DMT, 5-MeO-DMT) were used as controls. <b>A–B:</b> Induction of IFNγ (A) or IL-17 (B) production of autologous naive CD4⁺ T cells induced by moDC loaded by <i>E. coli</i>. Bacteria alone (E. coli; red bars) or bacteria in combination with 1 h DMT pre-treatment (E. coli + NN-DMT, E. coli+5-MeO-DMT; empty bars) were used to activate moDCs as written above. <b>C–D:</b> Cells were activated as in Fig4A–B; in this case inactivated influenza virus (IV) was added to the moDCs alone for 24 h (blue bars), or in combination with an 1 h NN-DMT or 5-MeO-DMT pre-treatment (IV + NN-DMT, IV + 5-MeO-DMT; empty bars). Data represent Mean + SEM values of triplicate measurements of three independent donors. Asterisk indicates statistical significance (<i>p</i><0.05).</p