The T cell-DC CD40L-CD40 axis, but not platelet CD40L, drives atherosclerosis
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ABSTRACT: Atherosclerosis, the underlying vascular cause of cardiovascular disease, has a strong inflammatory component. The co-stimulatory CD40-CD40 ligand (CD40L) signaling axis is a pivotal regulator of immune responses in atherosclerosis. However, therapeutic long-term inhibition of CD40L will severely compromise the immune system making it a non-viable treatment option. To circumvent this issue, cell-specific inhibition may present a better approach to target the CD40-CD40L axis. Therefore, we generated T cell and platelet-specific knockout mice for CD40L and apolipoprotein E, which were aged for 28 weeks to study their effects on immune status and atherosclerosis. Here, we show that T cell specific deficiency in CD40L signaling reduced plaque progression through hampered Th1 polarization as well as reduced antigen-dependent proliferation and oxLDL IgM production. DC-specific CD40 deficient mice displayed a similar phenotype. Platelet-specific CD40L deficiency, however, failed to decrease atherosclerosis, but ameliorated atherothrombosis. Together, our results illuminate the divergent cell-specific mechanisms of CD40-CD40L signaling in atherosclerosis, which may lead to advances in targeted therapies.
Project description:The CD40-CD40L dyad seems to play a prominent role fostering the immune-inflammatory response triggered by endothelial cell (EC)-T cell interaction. To comprehensively delineate the involvement of CD40 (TNFRSF5) in EC activation, we combined RNAi-mediated CD40 knock-down with comparative genome-wide transcriptional profiling of EC in response to T cell. We report the initiation of a profound stress response in ECs upon CD40-CD40L engagement through early up-regulation, among others, of the major pro-inflammatory NFkB and MAPK/SAPK pathways and their associated transcription factors. Moreover, we have identified novel genes regulated through the CD40-CD40L interaction, and pathways previously unrecognized to be induced by CD40 signaling in ECs. Thus, we document a strong down-regulation of endothelial APLN by CD40-CD40L interaction, which could lead to vascular tone dysfunction in atherosclerotic lesions. Conversely, CD40-mediated up-regulation of the viral immune surveillance system, notably TLR3, IFIH1, RIG-I, and RNASEL, establishes a reverse link from adaptive to innate immunity in ECs. Moreover, systematic enrichment analysis substantiates endothelial CD40 involvement in the transcriptional regulation of gene networks associated with adhesion and motility, immunity, cell fate control, hemostasis and metabolism. Our study also highlights the potency and specificity of CD40 siRNA mediated inhibition, and the relevance of CD40 signaling pathways for anti-inflammatory therapeutic intervention. Experiment Overall Design: Time course experiment comparing endothelial gene expression profiling of CD40-silenced versus non-silenced cultured cells using RNA interference. Two independent experiments were performed where HUVECs were siRNA-transfected and co-cultured with Jurkat D1.1 for 4, 10, 16 h and harvested for RNA extraction. Technical dye swap duplicates were performed for each of the two biological replicates in all three time points.
Project description:The CD40-CD40L dyad seems to play a prominent role fostering the immune-inflammatory response triggered by endothelial cell (EC)-T cell interaction. To comprehensively delineate the involvement of CD40 (TNFRSF5) in EC activation, we combined RNAi-mediated CD40 knock-down with comparative genome-wide transcriptional profiling of EC in response to T cell. We report the initiation of a profound stress response in ECs upon CD40-CD40L engagement through early up-regulation, among others, of the major pro-inflammatory NFkB and MAPK/SAPK pathways and their associated transcription factors. Moreover, we have identified novel genes regulated through the CD40-CD40L interaction, and pathways previously unrecognized to be induced by CD40 signaling in ECs. Thus, we document a strong down-regulation of endothelial APLN by CD40-CD40L interaction, which could lead to vascular tone dysfunction in atherosclerotic lesions. Conversely, CD40-mediated up-regulation of the viral immune surveillance system, notably TLR3, IFIH1, RIG-I, and RNASEL, establishes a reverse link from adaptive to innate immunity in ECs. Moreover, systematic enrichment analysis substantiates endothelial CD40 involvement in the transcriptional regulation of gene networks associated with adhesion and motility, immunity, cell fate control, hemostasis and metabolism. Our study also highlights the potency and specificity of CD40 siRNA mediated inhibition, and the relevance of CD40 signaling pathways for anti-inflammatory therapeutic intervention. Keywords: treated vs. untreated comparison, time course
Project description:Expression of CD40 in non-hematopoietic cells has been linked to inflammation. We presented evidence that CD40, a T-cell costimulatory molecule, is expressed in human β-cells and the engagement of CD40 in insulinoma cells activated the NFKB and ERK1/2 pathways. CD40 activation in human islets cells induced secretion of IL-8, MCP-1 and MIP-1 β, which is abrogated by inhibitors of NFkB and ERK1/2 inhibitors. In this study, we have studied gene expression mediated by CD40-CD40L interaction in islet cells. This approach identified 90 genes and transcripts exhibiting at least a 1.7 fold increase in their expression intensity after treatment with soluble CD40L. A significant number of genes were related to inflammation and oxidative stress. We have a strong overexpression of CXCL1 (Groα), CXCL2 (Mif2) and CXCL3; chemokines belonging to CXC family structurally related to Il-8. 11 genes were selected from this group and further quantified by Real Time PCR, including CXCL1. Activation of islet cells with CD40L induced the secretion of CXCL1 in a NFKB dependent manner. Engagement of CD40 in islet cells did not induce apoptosis, neither β-cell death and did not enhanced TNF-α mediated cell death as observed in insulinoma cells. CD40 activation in insulinoma cells, results in ERK1/2 dependent phsophorylation of synapsin I, a protein associated with the exocytosis machinery in neurons and β-cells. However, treatment of islets with soluble CD40L did not affect glucose induced insulin secretion. It has been reported that ductal cells always present in human islet preparations express CD40 constitutively (ref). We found that CD40-CD40L interaction in ductal cells, unlike in β-cells, induces secretion of diabetogenic cytokines IFNγ and TNF-α. Furthermore, incubation of islets containing ductal cells with CD40L decreased β-cells viability as assessed by measurement of their mitochondrial membrane potential Experiment Overall Design: We isolated islet cells from three patients. Part of islet cells from each patient has been treated with CD40L. We compared gene expression in treated cells vs untreated for each patient using dye-swap.
Project description:B-lymphocytes play major adaptive immune roles, producing antibody and driving cell mediated responses. However, how B-cells acutely differentiate in response to receptor signaling codes, including T-cell dependent versus independent cues, remains incompletely understood. To gain insights, we used multi-omic profiling to characterize ex vivo primary human B-cell transcriptomic, proteomic and metabolomic remodeling by B-cell receptor (BCR), Toll-like receptor 9 (TLR9), CD40-ligand (CD40L), interleukin-4 (IL4) or combinations thereof, highlighting key stimulus-specific phenotypes.
Project description:Inhibition of the co-stimulatory ligand CD40L has shown beneficial effects in many experimental models of auto-immune disease and inflammation. Here, we show that CD40L deficiency in T-cells in mice causes a reduction of CD4+ T cell activation and specifically a strong reduction in interferon- γ (IFN-γ) producing T helper 1 (Th1) cells. In vitro, we could not reproduce this APC-dependent effects, but found that T-cell CD40L affects cell death and proliferation. We identified receptor of activated C kinase (RACK1), the canonical PKC binding partner and known to drive proliferation and apoptosis, as a mediator of CD40L reverse signaling. Furthermore, we found that CD40L clustering stabilizes IFN-γ mediated Th1 polarization through STAT1, a known binding partner of RACK1. Together this highlights the importance of both CD40L forward and reverse signaling.
Project description:Inhibition of the costimulatory CD40-CD40L receptor/ligand dyad drastically reduces atherosclerosis. However, its long-term blockage can result in immune suppression. We recently identified small molecule inhibitors that block the interaction between CD40 and TNF Receptor Associated Factor (TRAF) 6 (TRAF-STOPs), while leaving CD40-TRAF2/3/5 interactions intact, thereby preserving CD40-mediated immunity. Here we further characterized the working mechanisms of TRAF-STOPs 6877002 and 6860766 in atherogenesis. Transcriptional profiling in CD40-activated macrophages showed that TRAF-STOP 6877002 had profound effects on the clusters ‘immune responses’ and ‘cell cycle progression’, whereas TRAF-STOP 6860766 only affected ‘immune responses’.
Project description:Chronic Lymphocytic Leukemia (CLL) cells multiply in secondary lymphoid tissue but the mechanisms leading to their proliferation are still uncertain. In addition to BCR-triggered signals, other microenvironmental factors might well be involved. In proliferation centres, leukemic B cells are in close contact with CD4+CD40L+ T cells. Therefore, we here dissected the signals provided by autologous activated T cells (Tact) to CLL cells. Although the gene expression profile induced by Tact was highly similar to that induced by sole CD40 signaling, an obvious difference was that Tact induced proliferation of CLL cells. We determined that stimulation with only CD40L+IL-21 was sufficient to induce robust proliferation in CLL cells. We then defined an IL-21-induced gene signature in CLL, containing components of JAK-STAT and apoptosis pathways, and this signature could be detected in lymph node (LN) samples from patients. Finally, we could detect IL-21 RNA and protein in LN, and IL-21 production ex vivo by LN CD4+CXCR5+ follicular helper T cells. These results indicate that, in addition to BCR signaling, activated T cells might contribute to CLL cell proliferation via CD40 and IL-21. Targeting these signaling pathways might offer new venues for treatment of CLL. CLL cells were cultured under different conditions for 16 hours and then sorted to purity as CD20+ CD5+ cells.
Project description:Autoantibodies that arise in autoimmunity can be present years to decades prior to the onset of disease manifestations. This suggests that the initial autoimmune trigger involves a peripheral lymphoid component, which then drives disease pathology in local tissues later in life. To explore the impact of early peripheral immune dysregulation on the progression of Sjögren’s Syndrome, we blocked the CD40-CD40L pathway in young female NOD.H-2h4 mice at 4 weeks of age with a single injection of anti-CD40L antibody, and collected total salivary gland at the age of week 8, 16 and 24. RNA was extracted and submitted to transcriptome profiling using Affymetrix microarray.
Project description:Chronic Lymphocytic Leukemia (CLL) cells multiply in secondary lymphoid tissue but the mechanisms leading to their proliferation are still uncertain. In addition to BCR-triggered signals, other microenvironmental factors might well be involved. In proliferation centres, leukemic B cells are in close contact with CD4+CD40L+ T cells. Therefore, we here dissected the signals provided by autologous activated T cells (Tact) to CLL cells. Although the gene expression profile induced by Tact was highly similar to that induced by sole CD40 signaling, an obvious difference was that Tact induced proliferation of CLL cells. We determined that stimulation with only CD40L+IL-21 was sufficient to induce robust proliferation in CLL cells. We then defined an IL-21-induced gene signature in CLL, containing components of JAK-STAT and apoptosis pathways, and this signature could be detected in lymph node (LN) samples from patients. Finally, we could detect IL-21 RNA and protein in LN, and IL-21 production ex vivo by LN CD4+CXCR5+ follicular helper T cells. These results indicate that, in addition to BCR signaling, activated T cells might contribute to CLL cell proliferation via CD40 and IL-21. Targeting these signaling pathways might offer new venues for treatment of CLL.