Project description:T helper type 2 (Th2) responses are induced by protease allergens and helminthes. However the molecular mechanisms that initiate Th2 responses are poorly understood. To obtain insight into this mechanism, we performed a microarray analysis of lymph node DCs stimulated in vitro with the protease allergen papain, or with LPS, a Th1 inducing stimulus. Key words: Th2 response, LPS, dendritic cells, Papain CD11c+ DCs were isolated from the lymph nodes of C57BL/6 mice, and cultured in vitro (1x106 DCs per ml) with 500 3T3-CD40L fibroblasts, either alone, or in the presence of papain (25 µg/ml) or LPS (1 µg/ml). 4h and 17h later, the cells were harvested and RNA isolated and processed for microarray analyses. RNA was extracted and processed from freshly isolated LN DCs. For a given time point, the expression profile of DCs treated with papain or LPS, were compared to that of untreated DCs
Project description:T helper type 2 (Th2) responses are induced by protease allergens and helminthes. However the molecular mechanisms that initiate Th2 responses are poorly understood. To obtain insight into this mechanism, we performed a microarray analysis of lymph node DCs stimulated in vitro with the protease allergen papain, or with LPS, a Th1 inducing stimulus. Key words: Th2 response, LPS, dendritic cells, Papain
Project description:Gene expression in wild-type and p38a-knockout dendritic cells (DCs) were compared. Lymph node dendritic cells were isolated from mice, and left unstimulated and stimulated with Pam3CSK4, a toll-like receptor 2 agonist. C57BL/6 wild-type mice, and dendritic cell-specific p38a-knockout mice on a C57BL/6 background were used for isolation of primary DCs.
Project description:Evolution of melanoma from a primary tumor to widespread metastasis is crucially dependent on lymphatic spread. The mechanisms regulating the initial step in metastatic dissemination via regional lymph nodes remain largely unknown. We have previously described a dysfunctional immune profile that precedes evidence of metastasis in the first node draining from the primary tumor, the sentinel lymph node (SLN). Herein, we explore the role of melanoma-derived extracellular vesicles (EVs) as mediators of this pre-metastatic niche through cargo-specific polarization of dendritic cells (DCs). Utilizing mass cytometry, pre-metastatic SLNs demonstrate compromised co-stimulatory CD80 expression compared to healthy lymph nodes. Similarly, DCs matured in vitro in the presence of melanoma EVs showed impaired co-stimulation and polarization towards a chronic inflammatory cytokine milieu. Profiling of melanoma EV cargo identified shared proteomic and RNA signatures including the signaling axis S100A8, S100A9 and cognate receptor TLR4. Mechanistically, S100A8 and S100A9 compromised DC maturation, a phenotype which was partially recovered following TLR4 blockade. Early evidence demonstrates similar EVs can be isolated from human afferent lymphatic fluid ex vivo. Taken together, we propose synergistic interactions among melanoma EV cargo are responsible for suppressing DC maturation, potentially explaining the survival of malignant melanocytes metastasizing into seemingly “normal” regional lymph nodes.
Project description:DCs treated with PTX (PTX-DC) is able to induce EAE like PTX as adjuvant whereas neither LPS nor DCs treated with LPS (LPS-DC) fails to induce EAE. We want to identify genes that are responsible for EAE induction in DCs and genes that are able to toloerize EAE in DCs through the microarray. Bone marrow derived dendritic cells are either unstimulated or stimulated with LPS and PTX for 24h respectively. Cells are harveseted for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Interleukin-2 (IL-2) is one of the molecules produced by mouse dendritic cells (DCs) after stimulation by Toll like receptor (TLR) agonists. By analogy with the events following T-cell receptor (TCR) engagement leading to IL-2 production we have observed that DC stimulation with lipopolysaccharide (LPS) induces Src-family kinase and phospholipase C (PLC)γ2 activation, influx of extracellular Ca2+ and calcineurin-dependent nuclear NFAT translocation. We have also observed that the initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. To determine the role of NFAT in LPS activated dendritic cells we have performed microarray analysis in conditions allowing or inhibiting NFAT activation. We show here that LPS-induced NFAT activation via CD14 is necessary to cause death of terminally differentiated DCs, an event that is essential for maintaining self-tolerance and preventing autoimmunity. Consequently, blocking this pathway in vivo causes prolonged DC survival and an increase in T cell priming capability. Gene expression analyses were performed using Affymetrix GeneChips in the following groups of murine bone marrow-derived dendritic cells: 1) CD14-deficient BMDCs stimulated with LPS; 2) wtBMDCs stimulated with LPS in presence of EGTA; 3) wtBMDCs stimulated with LPS. This experimental setting allowed us to select for effects due to Ca2+ fluxes and exclude the effects due to other causes, particularly the block of TRIF recruitment in CD14-deficient cells and the EGTA effects unrelated to Ca2+ chelation.
Project description:Dendritic cells (DCs) are a special class of leukocytes able to activate both innate and adaptive immune responses. They interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Upon antigen binding, PRRs instruct DCs for the appropriate priming of natural killer cells, followed by specific T-cell responses. Once completed the effector phase, DCs reach the terminal differentiation stage and eventually die by apoptosis. We have observed that following lipopolysaccharide (LPS)-stimulation the initiation of the apoptotic pathway in DCs is due the activation of NFAT proteins. Indeed, LPS induces Src-family kinase and phospholipase C (PLC)γ2 activation, influx of extracellular Ca2+ and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. According with this observation CD14-deficient DCs do not die following LPS stimulation. Nevertheless, CD14-deficient DC death following LPS activation can be restored by co-stimulating DCs with LPS and thapsigargin. Thapsigargin empties the intracellular calcium stores by blocking calcium pumping into the sarcoplasmic and endoplasmic reticulum and thereby activates plasma membrane calcium channels. This, in turn, allows an influx of calcium into the cytosol and NFAT activation. To identify the NFAT controlled apoptosis genes in LPS activated DCs we have performed a kinetic microarray analysis (0, 48 and 60 h) in conditions allowing or inhibiting NFAT activation. Four genes have been selected: Nur77, Gadd45g, Ddit3/Gadd153/Chop-10 and Tia1. To identify apoptosis genes selectively modulated by NFAT, a comparative kinetic (time points 0, 48 and 60 h) microarray analysis was performed in the following conditions: 1) wild type bone marrow derived DCs (wtBMDCs) stimulated with LPS; 2) CD14-deficient BMDCs stimulated with LPS; 3) wtBMDCs stimulated with LPS in presence of thapsigargin; 4) CD14-deficient BMDCs stimulated with LPS in presence of thapsigargin.
Project description:Multiple mechanisms restrain inflammation in neonates. Here we identify a population of pulmonary dendritic cells (DCs) that appear in the lungs and lung−draining lymph nodes between birth and two weeks of age and express intermediate levels of CD103 (CD103int). CD103int DCs express XCR1, CD205, and require the transcription factor, Batf3, suggesting that they belong to the cDC1 lineage. They also constitutively express CCR7 and spontaneously migrate to the lung−draining lymph node, where they promote stromal cell maturation and lymph node expansion, independently of microbial exposure and Trif− or MyD88−dependent signaling. CD103int DCs are transcriptionally related to efferocytic and tolerogenic DCs as well as mature, regulatory DCs. CD103int DCs efficiently acquire apoptotic cells and become activated through Mertk signaling, which also impairs CD8+ T cell activation. The appearance of CD103int DCs coincides with a temporal wave of apoptosis in developing lungs and explains, in part, impaired pulmonary immunity in neonatal mice.
Project description:T helper type 2 (Th2) responses are crucial for defense against infections by helminths and are responsible for the development of allergic reactions that can lead to severe clinical disorders, such as asthma or anaphylaxis, and ultimately to death. The induction of Th2 responses requires a specific activation process, triggered by specialized dendritic cells (DCs), by which naive CD4+ Th0 cells acquire the capacity to produce Th2 cytokines. However, the mechanistic basis of the functional specialization enabling DCs for the initiation of Th2 responses has remained elusive. Here we show that interleukin-4 (IL-4), a cytokine produced by basophils, mast cells and Th2-polarized CD4+ T helper cells, exerting a crucial function during anti-helminths and allergic Th2 responses, has a key role in the licensing/conditioning of DCs for the induction of Th2 responses, by bloking their potential to produce Th1-driving cytokines, such as IL-12, IL-18 and IL-23. Microarray analyses (duplicates) were for two types of comparisons: 1. moDCs stimulated with LPS from Escherichia coli versus C-moDCs non stimulated (control). 2. moDCs stimulated with LPS from Escherichia coli in presence of IL4 versus C-moDCs non stimulated (control).
Project description:We combined scRNA-seq and a photoconvertible mouse model to study the spatiotemporal dynamics of macrophages and dendritic cells (DCs) in murine tumours including their migration to the lymph node, including the effects of immune checkpoint therapy (anti-PD-L1).