Siponimod modulates the reaction of microglial cells to pro-inflammatory stimulation
Ontology highlight
ABSTRACT: Siponimod (Mayzent®), a sphingosine 1-phosphate receptor (S1PR) modulator which prevents lymphocyte egress from lymphoid tissues, is approved for the treatment of relapsing-remitting- and active secondary progressive multiple sclerosis. It can cross the blood-brain-barrier (BBB) and selectively binds to S1PR1 and S1PR5 expressed by several cell populations of the central nervous system (CNS) including microglia. To investigate wether Siponimod modulates the genetic signature of inflammed microglia, we performed a transcriptome analyses of primary rat microglial cells stimulated with LPS and With or Without Siponimod.
Project description:Lymphocytes can circulate as well as take residence within tissues. The mechanisms by which circulating populations are recruited to infected tissue sites have been characterized, but the extent and molecular basis of tissue-resident cell recirculation is enigmatic. Here, we show that helminth infection- or IL-25-induced redistribution of intestinal tissue-localized group 2 innate lymphoid cells (ILC2s) requires access to the lymphatic vessel network even though secondary lymphoid structures, which are essential signal hubs for adaptive lymphocyte differentiation and dispatch, are dispensable for tissue ILC2 mobilization. IL-25 signals induce a dramatic change in epigenetic landscape of intestinal ILC2s, enabling the expression of sphingosine-1-phosphate (S1P) receptors. S1PR5 is critical for ILC2 exit from intestinal tissue to lymph, whereas S1PR1 plays a dominant role in ILC2 egress from mesenteric lymph nodes to blood circulation and then to lung, where redistributed ILC2s contribute to tissue repair. The requirement of two S1PRs is largely due to the dynamic expression of the tissue-retention marker CD69, which mediates S1PR1 internalization. This stage-specific requirement of different S1P receptors for ILC2 redistribution during infection illustrates that innate and adaptive lymphocytes share a circulatory network frame but employ specialized navigation cues for their distinct migratory requirements.
Project description:Lymphocytes can circulate as well as take residence within tissues. The mechanisms by which circulating populations are recruited to infected tissue sites have been characterized, but the extent and molecular basis of tissue-resident cell recirculation is enigmatic. Here, we show that helminth infection- or IL-25-induced redistribution of intestinal tissue-localized group 2 innate lymphoid cells (ILC2s) requires access to the lymphatic vessel network even though secondary lymphoid structures, which are essential signal hubs for adaptive lymphocyte differentiation and dispatch, are dispensable for tissue ILC2 mobilization. IL-25 signals induce a dramatic change in epigenetic landscape of intestinal ILC2s, enabling the expression of sphingosine-1-phosphate (S1P) receptors. S1PR5 is critical for ILC2 exit from intestinal tissue to lymph, whereas S1PR1 plays a dominant role in ILC2 egress from mesenteric lymph nodes to blood circulation and then to lung, where redistributed ILC2s contribute to tissue repair. The requirement of two S1PRs is largely due to the dynamic expression of the tissue-retention marker CD69, which mediates S1PR1 internalization. This stage-specific requirement of different S1P receptors for ILC2 redistribution during infection illustrates that innate and adaptive lymphocytes share a circulatory network frame but employ specialized navigation cues for their distinct migratory requirements.
Project description:Effective immunity requires a large, diverse naïve T cell repertoire circulating among lymphoid organs in search of antigen. Sphingosine 1-phosphate (S1P) and its receptor S1PR1 contribute by both directing T cell migration and supporting T cell survival. Here, we address how S1P enables T cell survival, and the implications for patients treated with S1PR1 antagonists. Contrary to expectations, we found that S1PR1 limits apoptosis by maintaining the appropriate balance of BCL2 family members via restraint of JNK activity. Interestingly, the same residues of S1PR1 that enable receptor internalization are required to prevent JNK overactivation and limit apoptosis. Findings in mice were recapitulated in ulcerative colitis patients treated with the drug ozanimod, and the loss of naïve T cells limited B cell responses. Our findings highlight an unexpected effect of S1PR1 antagonists on the ability to mount immune responses within lymph nodes, beyond their effect on lymph node egress.
Project description:While histone H3 lysine 27 trimethylation (H3K27Me3) is associated with gene silencing, whether H3K27Me3 demethylation affects transcription and cell differentiation in vivo has remained elusive. To investigate this, we conditionally inactivated the two H3K27Me3 demethylases, Jmjd3 and Utx, in non-dividing intrathymic CD4+ T cell precursors. We show that both enzymes redundantly promote H3K27Me3 removal at, and expression of, a specific subset of genes involved in terminal thymocyte differentiation, especially S1pr1, encoding a sphingosine-phosphate receptor required for thymocyte egress.
Project description:Increased endothelial permeability and failure to repair is the hallmark of several vascular diseases including acute lung injury (ALI). However, little is known about the intrinsic pathways that activate endothelial cell (EC) regenerative programs and thereby tissue repair. Studies have invoked a crucial role of sphingosine-1-phosphate (S1P) in resolving endothelial hyperpermeability through activation of the G-protein coupled receptor, sphingosine-1-phosphate receptor 1 (S1PR1). Here, we addressed mechanisms of generation of S1PR1+ EC, which may prevent endothelial injury. Studies were made using inducible EC-S1PR1-/- (iEC-S1PR1-/-) mice and S1PR1-GFP reporter mice to trace the generation of S1PR1+ EC. We observed in a mouse model of endotoxemia that S1P generation induced the programming of S1PR1lo to S1PR1+ EC, which comprised 80% of lung EC. The transition of these cells was required for reestablishing the endothelial barrier. We also observed that conditional deletion of S1PR1 in EC increased vascular permeability. RNA-seq analysis of S1PR1+ EC showed enrichment of genes regulating S1P synthesis and transport, sphingosine kinase 1 (SPHK1) and SPNS2, respectively. The activation of transcription factors EGR1 and STAT3 were essential for transcribing SPHK1 and SPNS2, respectively, to increase S1P production that served to amplify S1PR1+ EC transition. Transplantation of S1PR1+ EC into injured lung vasculature restored endothelial integrity. Our findings show that generation of a S1PR1+ EC population activates the endothelial regenerative program mediating vascular endothelial repair, thus raising the possibility of harnessing this pathway to restore vascular homeostasis in inflammatory injury.
Project description:The biological functions of histone demethylases Jmjd3 and Utx remain poorly understood. We assessed such functions in developing T cells, using conditional (CD4-Cre-mediated) gene disruption, by inactivating Kdm6a and Kdm6b, respectively encoding Utx and Jmjd3, in immature CD4+CD8+ thymocytes. We compared microarray gene expression in mature (Va2hi CD24lo) mutant and wild-type CD4+CD8- thymocytes carrying the OT-II TCR transgene. We show that Jmjd3 and Utx redundantly promote H3K27Me3 removal at, and expression of, a specific subset of genes involved in terminal thymocyte differentiation, especially S1pr1, encoding a sphingosine-phosphate receptor required for thymocyte egress.
Project description:A synthetic analog of sphingosine named FTY720 (Fingolimod), phosphorylated by sphingosine kinase-2, interacts with sphingosine-1-phosphate (S1P) receptors expressed on various cells. FTY720 suppresses the disease activity of multiple sclerosis (MS) chiefly by inhibiting S1P-dependent egress of autoreactive T lymphocytes from secondary lymphoid organs, and possibly by exerting anti-inflammmatory and neuroprotective effects directly on brain cells. However, at present, biological effects of FTY720 on human microglia are largely unknown. We studied FTY720-mediated apoptosis of a human microglia cell line HMO6. The exposure of HMO6 cells to non-phosphorylated FTY720 (FTY720-non-P) induced apoptosis in a dose-dependent manner with IC50 of 10.6±2.0 microM, accompanied by the cleavage of caspase-7 and caspase-3 but not of caspase-9. The apoptosis was inhibited by Z-DQMD-FMK, a caspase-3 inhibitor, but not by Pertussis toxin, a Gi protein inhibitor, suramin, a S1P3/S1P5 inhibitor, or W123, a S1P1 competitive antagonist, although HMO6 expressed S1P1, S1P2, and S1P3. Furthermore, both phosphorylated FTY720 (FTY720-P) and SEW2871, a S1P1 selective agonist did not induce apoptosis of HMO6. Genome-wide gene expression profiling and molecular network analysis indicated activation of transcriptional regulation by sterol regulatory element-binding protein (SREBP) in FTY720-non-P-treated HMO6 cells. Western blot verified activation of SREBP2 in these cells, and apoptosis was enhanced by pretreatment with simvastatin, an activator of SREBP2, and by overexpression of the N-terminal fragment of SREBP2. These observations suggest that FTY720-non-P-induced apoptosis of HMO6 human microglia is independent of S1P receptor binding, and positively regulated by the SREBP2-dependent proapoptotic signaling pathway. The HMO6 cell line was established by immortalizing cultured microglia isolated from human embryonic telencephalon tissues with a retroviral vector PASK1.2 encoding v-myc oncogene (Nagai et al. Neurobiol. Dis. 8: 1057-1068, 2001). HMO6 cells express the markers of the microglia/macrophage lineage cells, including CD11b, CD68, CD86, HLA-ABC, HLA-DR, and ricinus communis agglutinin lectin-1 (RCA), serving as a model of human microglia both in vitro and in vivo. The cells were exposed for 2 hours to 10 microM FTY720-non-P dissolved in dimethyl sulfoxide (DMSO) or ethanol or exposed to the vehicle.
Project description:Sphingosine 1-phosphate (S1P) is a lysosphingolipid with anti-atherogenic properties, but mechanisms underlying its effects remain unclear. We here analyzed the consequences of overexpressing the S1P receptor type 1 (S1pr1) on peritoneal macrophage gene expression. To amplify S1pr1 signaling in macrophages, double transgenic mice expressing mouse S1pr1 in mononuclear cells were constructed by crossing two lines. The S1pr1-KI line carries a transgenic cassette in the Rosa 26 locus harboring the mouse S1P1 cDNA and separated from the CAG promoter by a lox-Stop-lox insert. S1pr1-KI mice were then crossed to LysMCre mice expressing Cre recombinase under the control of the lysozyme M promoter, which drives macrophage expression. In the offspring the lox-Stop-lox insert is excised in Cre-expressing cells (macrophages), which induces cDNA expression driven by the CAG promoter. At 12 weeks of age, peritoneal leukocytes were isolated from S1pr1-LysMCre mice and control mice (S1pr1-KI) by peritoneal lavage and seeded in cell culture plates. After 2 h non-adherent cells were removed, total RNA was isolated from the remaining macrophages and subjected to microarray gene expression analysis.
Project description:While histone H3 lysine 27 trimethylation (H3K27Me3) is associated with gene silencing, whether H3K27Me3 demethylation affects transcription and cell differentiation in vivo has remained elusive. To investigate this, we conditionally inactivated the two H3K27Me3 demethylases, Jmjd3 and Utx, in non-dividing intrathymic CD4+ T cell precursors. We show that both enzymes redundantly promote H3K27Me3 removal at, and expression of, a specific subset of genes involved in terminal thymocyte differentiation, especially S1pr1, encoding a sphingosine-phosphate receptor required for thymocyte egress. Floxed alleles of the genes encoding Utx and Jmjd3 (Kdm6a and Kdm6b, respectively) were deleted in double positive (DP) thymocytes carrying a CD4 Cre transgene. Genome-wide H3K27Me3 ChipSeq was performed on (i) pre-selection (CD69lo) DP thymocytes from wild-type mice carrying an endogenous polyclonal TCR repertoire, (ii) mature (TCRhi CD24lo) CD4 SP thymocytes from wild type (Wt), Jmjd3KO, UtxKO and dKO mice carrying an endogenous polyclonal TCR repertoire and (iii) mature (Va2hi CD24lo) CD4 SP thymocytes from wild type and dKO mice carrying the OTII TCR transgene.
Project description:The biological functions of histone demethylases Jmjd3 and Utx remain poorly understood. We assessed such functions in developing T cells, using conditional (CD4-Cre-mediated) gene disruption, by inactivating Kdm6a and Kdm6b, respectively encoding Utx and Jmjd3, in immature CD4+CD8+ thymocytes. We compared microarray gene expression in mature (Va2hi CD24lo) mutant and wild-type CD4+CD8- thymocytes carrying the OT-II TCR transgene. We show that Jmjd3 and Utx redundantly promote H3K27Me3 removal at, and expression of, a specific subset of genes involved in terminal thymocyte differentiation, especially S1pr1, encoding a sphingosine-phosphate receptor required for thymocyte egress. Mature (Va2hi CD24lo) CD4 thymocytes were sorted from freshly prepared single-cell suspensions OT-II TCR transgenic thymocytes deficient for Utx and Jmjd3 (dKO, CD4-Cre conditional deletion of floxed Kdm6a and Kdm6b alleles), and from Cre-negative controls (wild-type). Total RNA was extracted from sorted thymocytes using the RNeasy Plus Mini Kit (Qiagen) and processed for microarray analyses (Affymetrix Mouse Exon 1.0 ST array) at the NCI microarray facility, following the manufacturer’s recommendation. Data is generated from 3 replicates from each experiment.