TLR2-induced CD8+ T cell deactivation shapes dendritic cell differentiation in the bone marrow during sepsis
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ABSTRACT: Sepsis is associated with profound immune dysregulation that increases the risk for life-threatening secondary infections: Dendritic cells (DCs) undergo functional reprogramming due to yet unknown changes during differentiation in the bone marrow (BM). We investigated whether T cells alter the gene expression in the bone marrow during sepsis using microarrays.
Project description:We performed RNA-seq analysis using primary murine bone marrow derived dendritic cells (BM-DCs) for recombinant articulatin B chain (rATB) treatment. We reported that rATB regulates immunological related genes in BM-DCs. rATB induces CD4 T cell type I driven and maturation genes in BM-DCs.
Project description:Platelets have a wide range of functions including critical roles in hemostasis, thrombosis, and immunity. We hypothesized that during acute inflammation, such as in life-threatening sepsis, there are fundamental changes in the sites of platelet production and phenotypes of resultant platelets. Here, we showed during sepsis that the spleen is a major site of megakaryopoiesis and platelet production. Sepsis provoked an adrenergic-dependent mobilization of megakaryocyte-erythrocyte progenitors (MEPs) from the bone marrow to the spleen where interleukin-3 (IL-3) induced their differentiation into megakaryocytes. In the spleen, immune-skewed megakaryocytes produced a CD40L-high platelet population with potent immunomodulatory functions. Transfusions of post-sepsis platelets enriched from splenic production enhanced immune responses and reduced overall mortality in sepsis-challenged animals. These findings identify a spleen-derived protective platelet population that may be broadly immunomodulatory in acute inflammatory states such as sepsis.
Project description:Sepsis is associated with profound immune dysregulation that increases the risk for life-threatening secondary infections: Dendritic cells (DCs) undergo functional reprogramming due to yet unknown changes during differentiation in the bone marrow (BM). In parallel, lymphopenia and exhaustion of T lymphocytes interfere with antigen-specific adaptive immunity. We hypothesized that there exists a link between T cells and the modulation of DC differentiation in the BM during murine polymicrobial sepsis. Sepsis was induced by cecal ligation and puncture (CLP), a model for human bacterial sepsis. At different time points after CLP, the BM and spleen were analyzed in terms of T-cell subpopulations, activation, and Interferon (IFN)-γ synthesis as well as the number of pre-DCs. BM-derived DCs were generated in vitro. We observed that naïve and virtual memory CD8+ T cells, but not CD4+ T cells, were activated in an antigen-independent manner and accumulated in the BM early after CLP, whereas lymphopenia was evident in the spleen. The number of pre-DCs strongly declined during acute sepsis in the BM and almost recovered by day 4 after CLP, which required the presence of CD8+ T cells. Adoptive transfer experiments and in vitro studies with purified T cells revealed that Toll-like receptor 2 (TLR2) signaling in CD8+ T cells suppressed their capacity to secrete IFN-γ and was sufficient to change the transcriptome of the BM during sepsis. Moreover, the diminished IFN-γ production of CD8+ T cells favored the differentiation of DCs with increased production of the immune-activating cytokine Interleukin (IL)-12. These data identify a novel role of CD8+ T cells in the BM during sepsis as they sense TLR2 ligands and control the number and function of de novo differentiating DCs.
Project description:The goal of this study is to investigate the involvement of inflammation in Alzheimer’s disease (AD) and to clarify the signaling pathways involved in the presence of beta-amyloidosis, a hallmark of AD pathogenesis, to help identifying potential targets for therapy. To do that, we isolated bone marrow-derived progenitor cells from femurs, tibiae and hip bones of non-transgenic C57BL/6 mice according to established protocols , and we maturated them with LPS. To obtain an unbiased view of gene regulation in mouse bone marrow-derived dendritic cells (BM-DCs) exposed to pre-aggregated beta-amyloid peptide (Aβ) oligomers, we analyzed the transcriptome of untreated immature control BM-DCs (‘Ctrl’), LPS-treated BM-DCs (’LPS’), Aβ1-42 oligomer-treated BM-DCs (‘Aβ‘) and BM-DCs treated with Aβ1-42 oligomers and LPS (‘Aβ+LPS‘) via explorative RNA-sequencing.
Project description:Sepsis is a leading cause of death worldwide, with most patient mortality stemming from lingering immunosuppression in sepsis survivors. This is due in part to immune dysfunction stemming from monocyte exhaustion, a phenotype of reduced antigen presentation, altered CD14/CD16 inflammatory subtypes, and disrupted cytokine production. Whereas previous research demonstrated improved sepsis survival in Ticam2-/- mice, the contribution of TICAM2 signaling to long-term exhaustion memory was unknown. Using a cecal slurry injection sepsis model, we monitored the establishment and recovery of monocyte exhaustion in Ticam2-/- mice. Like wild-type controls, Ticam2-/- monocytes develop an exhaustion phenotype defined by CD38high; CX3CR1low; MHCIIlow cell surface expression 48 hours after sepsis onset. Time course analysis of sepsis patient blood samples revealed a similar effect in human monocytes, which steadily transition into a CD38high; CX3CR1low; HLA-DRlow state within four days of hospital admittance. To determine the impact of TICAM2 ablation on innate epigenetic memory in sepsis, we measured genome-wide DNA methylation in bone marrow monocytes and found that Ticam2-/- cells exhibit a unique profile of altered methylation at CEBPE binding sites and regulatory features for key immune genes such as Dmkn and Btg1. Finally, after one week of sepsis recovery, we profiled bone marrow and splenic reservoir monocytes in Ticam2-/- mice and found that, in contrast to the persistent exhaustion observed in wild-type monocytes, Ticam2-/- monocytes largely resembled healthy controls. Thus, in addition to improving survival during the inflammatory phase of sepsis progression, TICAM2 ablation facilitates the resolution of monocyte exhaustion in sepsis survivors.
Project description:Microarray experiments were performed to compare the gene expression profiles exhibited by immature and activated bone-marrow (BM) derived conventional DCs (BM-cDCs) and plasmacytoid DCs (BM-pDCs) from WT and miR155-/- mice. (time points 0, 4 and 24 hours)
Project description:Sepsis is a life-threatening condition caused by a dysregulated host response to infection.Although our understanding in the pathophysiological features of sepsis has increased significantly during the past decades, there is still lack of mechanism of sepis.Neutrophils are important regulators against invading pathogens, and their role during sepsis has been studied extensively. However, whether neutrophils could inhibit the immune response of CD8+T cells and the mechanism is unkown in sepsis.
Project description:To compare tumor associated macrophage (TAM) from naïve and sepsis surviving mice we have employed Agilent microarrays slides with almost 60,000 genes (39,430 mRNA and 16,251 long non coding RNAs). Other experiments we conducted demonstrated TAM accumulation was increased in post-sepsis subjects. For this reason, we asked if TAM from post-sepsis mice could also exhibit a different gene expression profile. Sepsis was induced by cecal and ligation puncture. Naïve mice were used as control group. All animals were treated with ertapenem (20 mg/kg, i.p., 6 hours after surgery, and then each 12 hours for 3 days). B16-F10 melanoma (30,000 cells) were injected subcutaneously at day 14 after sepsis induction. Fourteen days after tumor inoculation, animals were killed and tumors were harvested and digested (collagenase and DNAse). TAM was isolated by a Percoll gradient (70/30) followed by a 1-hour adhesion protocol, reaching a purity of ~75%. For comparative reasons, we assessed TAM from post-sepsis (n = 4), TAM from naïve mice (n = 4), bone marrow derived macrophage from naïve (n = 4) and from post-sepsis (n = 4), M1-polarized macrophage (n = 4) and M2-polarized macrophage (n = 4). We found only minor gene expression differences between TAM from naïve and from post-sepsis mice (61 genes were up-regulated and 98 genes were down-regulated, fold-change > 0.58 or < -0.58, and p < 0.01). We found genes related to leukocyte activation were down-regulated in TAM from post-sepsis mice (e.g. Ccr7, Cd86, H2-Ab1), as well as genes related to antigen processing and presentation of peptide or polysaccharide antigen via MHC class II (H2-DMb1, Cd74, H2-Eb1, H2-Ob). A gene related to M2 polarization was up-regulated (Marco). Also, we found a down-regulation of Nfkbid in post-sepsis-derived TAM. This led us to hypothesize TAM from post-sepsis mice exhibit a more M2-like phenotype, which may in part contribute to post-sepsis tumor expansion. Three independent experiments were conducted for TAM obtaining, each experiment using n = 4 for naïve and n = 4 for post-sepsis. We selected the 4 best within a group of 12 samples, following A260/280 and A260/230 ratios. For bone marrow derived macrophage from naïve and from post-sepsis, and for M1 and M2-polarized macrophage, we conducted two independent experiments using n = 3 per group. The best 4 samples in each group was selected to microarray processing and analysis.