ABSTRACT
Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell leukemia/lymphoma caused by human T-cell lymphotropic virus type I (HTLV-1). Acadesine or 5-aminoimidazole-4-carboxamide riboside (AICAR) is an AMP-activated protein kinase (AMPK) activator that was recently shown to have tumor suppressive effects on B cell chronic lymphocytic leukemia, but not ATL. This study evaluated the cytotoxic effects of AICAR on ATL-related cell lines and its anti-tumor activity. Here, we demonstrated that AICAR induced cell death via apoptosis and the mitochondrial membrane depolarization of ATL-related cell lines (S1T, MT-1, and MT-2) but not non-HTLV-1-infected Jurkat cells. However, AICAR did not increase the phosphorylation levels of AMPKα. In addition, AICAR increased the expression of the death receptors (DR) DR4 and DR5, and necroptosis-related proteins including phosphorylated receptor-interacting protein family members and the mixed lineage kinase domain-like protein. Interestingly, HTLV-1 Tax, an HTLV-1-encoded oncogenic factor, did not affect AICAR-induced apoptosis. Furthermore, AICAR inhibited the growth of human ATL tumor xenografts in NOD/SCID/gamma mice in vivo. Together, these results suggest that AICAR induces AMPK-independent cell death in ATL-related cell lines and has anti-tumor activity, indicating that it might be a therapeutic agent for ATL.
Subject(s)
Human T-lymphotropic virus 1 , Leukemia-Lymphoma, Adult T-Cell , Mice , Adult , Animals , Humans , AMP-Activated Protein Kinases/metabolism , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Leukemia-Lymphoma, Adult T-Cell/pathology , Mice, Inbred NOD , Mice, SCID , ApoptosisABSTRACT
Adult T-cell leukemia/lymphoma (ATL) is a hematopoietic malignancy with a poor prognosis that develops in approximately 5% of human T-cell leukemia virus type 1 (HTLV-1) carriers. Cyclin-dependent kinase 9 (CDK9), together with Cyclin T, forms a transcription elongation factor, positive transcription elongation factor b (P-TEFb). P-TEFb promotes transcriptional elongation by phosphorylating the second serine (Ser2) of the seven amino acid repeat sequence in the C-terminal domain of RNA polymerase II (RNAP II). CDK9 inhibitors suppress cell proliferation by inducing apoptosis in chronic lymphocytic leukemia and breast cancer but there are no reports on autophagy of CDK9 inhibitors. Here, we investigated the effect of LY2857785, a novel CDK9 selective inhibitor, on cell death in ATL-related cell lines in vitro, freshly isolated cells from ATL patients ex vivo, and on ATL tumor xenografts in NOD/SCID mice in vivo. LY2857785 significantly reduced cell viability and induced apoptosis, as shown by annexin V-positive cells, cleaved poly(ADP-ribose) polymerase (PARP), and cleaved caspase-3, and suppressed the levels of anti-apoptotic protein myeloid cell leukemia-1 (MCL-1). LY2857785 decreased RNAP II Ser2 phosphorylation and downstream c-Myc protein levels. Interestingly, LY2857785 also increased microtubule-associated proteins 1A/1B light chain 3B (LC3)-II binding to autophagosome membranes. Furthermore, LY2857785 decreased the viability of freshly isolated ATL cells and induced apoptosis. Finally, LY2857785 significantly decreased the growth of ATL tumor xenografts. These results suggest that LY2857785 induces cell death of ATL cells by MCL-1-dependent apoptosis and autophagy and has anti-tumor activity.
Subject(s)
Breast Neoplasms , Leukemia-Lymphoma, Adult T-Cell , Lymphoma , Mice , Adult , Animals , Humans , Female , Mice, Inbred NOD , Mice, SCID , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Positive Transcriptional Elongation Factor B , Myeloid Cell Leukemia Sequence 1 Protein , Protein Kinase Inhibitors , Apoptosis , Autophagy , Cyclin-Dependent Kinase 9ABSTRACT
Adult T-cell leukemia/lymphoma (ATL) develops after a long period of human T-cell leukemia virus (HTLV)-1 infection and is associated with host aging in addition to genetic abnormalities in HTLV-1 infected cells. SIRT1 is a histone deacetylase involved in cell cycle and apoptosis. We previously showed the high expression of SIRT1 protein in peripheral blood mononuclear cells from patients with ATL. There have been many reports that SIRT1 inhibitors show tumor-suppressive effects. On the other hand, SIRT1 activator SRT1720 induces the cell death of multiple myeloma and breast cancer cells. However, the effect of SRT1720 on ATL is unknown. This study aimed to evaluate the effect of SRT1720 on cell death in leukemic cell lines in vitro and freshly isolated ATL cells ex vivo and in an ATL in vivo mouse model. SRT1720 reduced cell viability in vitro and ex vivo. Additionally, SRT1720 increased the number of apoptotic cells, as shown by annexin V positive cells, cleaved poly (ADP-ribose) polymerase 1, cleaved caspase-3, and fragmented DNA. SRT1720 also induced mitochondrial outer membrane permeabilization with the generation of mitochondrial reactive oxygen species and autophagy. However, SIRT1 knockdown did not attenuate SRT1720-induced cell death in leukemic cell lines. Finally, SRT1720 treatment decreased the growth of human ATL tumor xenografts in immunodeficient mice. Our study shows that while SRT1720 does not target SIRT1, it induces cell death in ATL cells via apoptosis and autophagy and has antitumor activity.
Subject(s)
Heterocyclic Compounds, 4 or More Rings , Leukemia-Lymphoma, Adult T-Cell , Animals , Apoptosis , Cell Death , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Leukemia-Lymphoma, Adult T-Cell/genetics , Leukemia-Lymphoma, Adult T-Cell/metabolism , Leukocytes, Mononuclear/metabolism , Mice , Sirtuin 1/genetics , Sirtuin 1/metabolismABSTRACT
An important function of aromatase in the brain is conversion of testosterone secreted from the testis into estradiol. Estradiol produced in the brain is thought to be deeply involved in the formation of sexually dimorphic nuclei and sexual behavior as a neurosteroid. We analyzed the brain-specific promoter to elucidate the control mechanisms of brain aromatase expression that may be highly involved in sexual differentiation of the brain. The 202-bp upstream region of the brain-specific exon 1 has three types of cis-acting elements, aro-AI, AII, and B. We isolated ARP-1 as an aro-AII-binding protein by yeast one-hybrid screening from a cDNA library of mouse fetal brains. ARP-1 is a member of the nuclear receptor superfamily and functions as an orphan-type transcription factor. ARP-1 protein synthesized in vitro showed the same binding property to the aro-AII site as nuclear extract from fetal brains. To determine how the promoter is involved in brain-specific transcription of the aromatase gene, we first detected the in vivo occupancy of the aro-AII site by ARP-1 using chromatin immunoprecipitation assays. Diencephalic regions of fetal brains at embryonic day 16 were analyzed, which revealed ARP-1 recruitment to the aro-AII site. To analyze the effects of ARP-1 on transcriptional regulation of the brain-specific aromatase promoter, a luciferase reporter plasmid driven by the brain-specific promoter was transfected into CV-1 cells together with a plasmid expressing ARP-1 protein. These analyses revealed that ARP-1 induced promoter activity in a dose-dependent manner. Furthermore, to determine whether ARP-1 is required for aromatase expression in neurons, ARP-1 knockdown was conducted in neuronal cell primary culture. Knockdown of ARP-1 significantly suppressed the increase in aromatase mRNA observed in cultured neurons. These results indicate that ARP-1 is involved in the transcriptional regulation of the brain-specific promoter of the aromatase gene.
Subject(s)
Aromatase/metabolism , Brain/metabolism , COUP Transcription Factor II/metabolism , Gene Expression Regulation , Promoter Regions, Genetic , Receptors, Cytoplasmic and Nuclear/metabolism , Transcription, Genetic , Animals , Aromatase/genetics , COUP Transcription Factor II/genetics , Humans , Mice , Receptors, Cytoplasmic and Nuclear/geneticsABSTRACT
AIMS: Thrombin formation is increased in patients with acute cerebral ischemic stroke, and augments coagulation and inflammation in the brain. Administration of antithrombin (AT) was previously reported to be protective against renal and myocardial ischemic injury. Thus, we hypothesized that treatment with AT would be neuroprotective against cerebral ischemic injury. This study evaluated the effects of AT treatment on ischemic inflammation and brain damage in mice subjected to middle cerebral artery occlusion (MCAO). MAIN METHODS: A mouse model of 4-hour MCAO was used to induce ischemic brain injury. Recombinant AT gamma was administered intravenously immediately after reperfusion at 4 h after MCAO. Infarct volume, neurological deficit, and regional cerebral blood flow (rCBF) were measured at 24 h after MCAO. To evaluate the effect of AT gamma on ischemic inflammation, we measured the number of Iba1-positive cells (marker of macrophage/microglial activation) and levels of proinflammatory cytokines. Further, we investigated the direct anti-inflammatory effects of rAT in the J774.1 cell line. KEY FINDINGS: Treatment with AT gamma (480 U/kg) reduced infarct volume and neurological deficit, and improved rCBF, in MCAO mice. Moreover, AT gamma treatment decreased the number of Iba1-positive cells and levels of proinflammatory cytokines. In vitro, treatment with thrombin significantly increased proinflammatory cytokine levels, which was significantly reduced by pretreatment with AT gamma. SIGNIFICANCE: Treatment with AT showed neuroprotective effects via anticoagulation actions, as well as direct anti-inflammatory effects on macrophage/microglial activation. These data suggest that AT may be a useful new therapeutic option for cerebral ischemia.
Subject(s)
Antithrombins/pharmacology , Brain Ischemia/drug therapy , Neuroprotective Agents/pharmacology , Stroke/drug therapy , Animals , Antithrombins/administration & dosage , Brain Ischemia/pathology , Cell Line , Cytokines/metabolism , Disease Models, Animal , Infarction, Middle Cerebral Artery , Inflammation/drug therapy , Inflammation/pathology , Macrophage Activation/drug effects , Macrophages/drug effects , Macrophages/metabolism , Male , Mice , Mice, Inbred BALB C , Microglia/drug effects , Microglia/metabolism , Neuroprotective Agents/administration & dosage , Recombinant Proteins , Stroke/pathologyABSTRACT
Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell neoplasm with poor prognosis that develops after chronic infection with human T-cell leukemia virus type 1 (HTLV-1). Although AMP-activated protein kinase (AMPK) is a critical cellular energy sensor, it has recently become clear that AMPK can act as a tumor regulator. Here, we assessed the expression of AMPK in primary ATL cells and the effects of dorsomorphin, an AMPK inhibitor, on primary ATL cells and HTLV-1-infected T-cell lines. AMPK expression in acute and chronic ATL patients was significantly higher than in asymptomatic HTLV-1 carriers and healthy donors. Dorsomorphin induced apoptosis in peripheral blood mononuclear cells from ATL patients. Dorsomorphin also induced dose- and time-dependent apoptosis in HTLV-1-infected T-cell lines. Dorsomorphin increased the production of intracellular reactive oxygen species (ROS) and induced ataxia telangiectasia-mutated Ser1981 phosphorylation and p53 accumulation. These results indicated that dorsomorphin induces apoptosis via ROS-mediated DNA damage in HTLV-1-infected T-cell lines. Furthermore, dorsomorphin suppressed the growth of human ATL tumor xenografts in NOD/SCID mice. Together, these data suggest that AMPK could be a candidate therapeutic target for ATL and that dorsomorphin could be a therapeutic agent for ATL.
Subject(s)
AMP-Activated Protein Kinases/metabolism , Apoptosis/drug effects , Leukemia-Lymphoma, Adult T-Cell/metabolism , Pyrazoles/pharmacology , Pyrimidines/pharmacology , Adult , Animals , Cell Line, Tumor , Female , Humans , Leukemia-Lymphoma, Adult T-Cell/drug therapy , Leukemia-Lymphoma, Adult T-Cell/pathology , Mice , Mice, Inbred NOD , Mice, SCID , Protein Kinase Inhibitors/pharmacology , Xenograft Model Antitumor Assays/methodsABSTRACT
BACKGROUND: Although DNAM-1 is an activating receptor constitutively expressed on the majority of NK cells, CD8+ T cells, CD4+ T cells, monocytes, and platelets in human, several evidences demonstrated that a small population in B-lineage cells also expressed DNAM-1. However, the expression profile of DNAM-1 on B-lineage cells and its function remain obscure. Previous reports revealed that a considerable number of leukocytes including B cells in the peripheral blood conjugated to platelet. Thus, the proportion of DNAM-1+ B-lineage cells determined by flow cytometry analysis in the previous reports might be overestimated. METHODS: We examined whether platelets conjugate B cells and then analyzed the expression of DNAM-1 on the subpopulations of B-lineage cells according to their maturation stages after exclusion of platelet-conjugated B cells. We also assessed the involvement of DNAM-1 in IL-10 and antibody production from cultured B-lineage cells stimulated with CpG-ODN. RESULTS: Approximately 10% of human DNAM-1+ CD19+ B cells in the peripheral blood conjugated to platelets, resulting in the overestimation of the proportion of DNAM-1+ B cells. After exclusion of platelet-conjugating B cells, we show that DNAM-1 expression was detected on subpopulations of memory B cells, plasmablasts, and plasma cells and upregulated by stimulation with CpG-ODN. Moreover, DNAM-1 was involved in IL-10 and antibody productions by B cells after CpG-ODN stimulation. CONCLUSIONS: DNAM-1 may be involved in B-lineage cell-mediated immune responses.
Subject(s)
Antigens, Differentiation, T-Lymphocyte/blood , B-Lymphocytes/immunology , Flow Cytometry , Interleukin-10/genetics , Antigens, Differentiation, T-Lymphocyte/immunology , B-Lymphocytes/pathology , Blood Platelets/immunology , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , Cell Lineage/genetics , Cell Lineage/immunology , Female , Gene Expression Regulation/immunology , Humans , Interleukin-10/immunology , Killer Cells, Natural/immunology , Male , Monocytes/immunologyABSTRACT
Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature T lymphocytes induced by human T-cell leukemia virus-1 and has a poor outcome. New molecular targets for the prevention and treatment of ATL are needed urgently. We previously reported high expression of Sirtuin 1, a nicotinamide adenine dinucleotide (NAD+)-dependent histone/protein deacetylase, in primary acute-type ATL cells. NAD+ biosynthesis via nicotinamide phosphoribosyltransferase (NAMPT) modulates Sirtuin 1 activity. Here, we examined the expression and effects of inhibiting NAMPT, a rate-limiting enzyme in NAD+ biosynthesis, in ATL cells. We found that peripheral blood mononuclear cells from patients with acute-type ATL expressed significantly higher levels of NAMPT protein than cells from healthy subjects. FK866, a NAMPT inhibitor, induced apoptosis of freshly isolated ATL cells ex vivo and HTLV-1-infected T-cell lines in vitro, which was accompanied by activation of caspases, DNA fragmentation, and disruption of mitochondrial transmembrane potential. However, a pan-caspase inhibitor failed to prevent this FK866-induced cell death, while FK866 increased the caspase-independent cell death mediator endonuclease G. Intriguingly, FK866 also activated autophagy, as demonstrated by increases in protein levels of autophagosome marker LC3-II. Thus, FK866 simultaneously activated apoptosis and autophagy. Finally, FK866 treatment markedly decreased the growth of human ATL tumor xenografts in immunodeficient mice. We showed that NAMPT is highly expressed in primary ATL cells ex vivo, and that FK866 induces autophagy and caspase-dependent and -independent cell death pathways in vitro and has an anti-tumor activity in vivo. These results suggest a novel therapeutic strategy for patients with this fatal disease.
Subject(s)
Antineoplastic Agents/pharmacology , Cytokines/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Leukemia-Lymphoma, Adult T-Cell/pathology , Nicotinamide Phosphoribosyltransferase/antagonists & inhibitors , Apoptosis/drug effects , Autophagy/drug effects , Caspase 3/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , HumansABSTRACT
Obesity commonly occurs in postmenopausal women, increasing the risk of various diseases. Estrogen can prevent obesity by activating lipid metabolism and suppressing depressive behavior. However, the reasons for obesity in postmenopausal women are not clearly elucidated. To mimic the effect of estrogen decline in postmenopausal women, we analyzed the behavior and the lipid metabolism-related genes, PPARγ and CD36 in ovariectomized (OVX) mice. The OVX mice showed increased visceral fat mass and PPARγ and CD36 expression in the visceral fat. In contrast, they were not significantly affected in terms of physical activity and food intake. Further, subcutaneous supplementation of estrogen effectively suppressed the increase in subcutaneous and visceral fat mass in OVX mice. We conclude that obesity in postmenopausal women is unlikely to be caused by overeating and reduction in physical activity, and subcutaneous supplementation of estrogen is an effective strategy to prevent obesity in postmenopausal women.
ABSTRACT
BACKGROUND: Sirtuin 2 (SIRT2) is a member of the sirtuin family, nicotinamide adenine dinucleotide+-dependent deacylases, which participates in modulation of cell cycle control, neurodegeneration, and tumorigenesis. SIRT2 expression increases in acute myeloid leukemia blasts. Downregulation of SIRT2 using siRNA causes apoptosis of HeLa cells. Therefore, selective inhibitors of SIRT2 are candidate therapeutic agents for cancer. Adult T-cell leukemia/lymphoma (ATL) is a T-cell malignancy that has a poor prognosis and develops after long-term infection with human T-cell leukemia virus (HTLV)-1. Sirtuin 1 inhibition has been shown to induce apoptosis and autophagy in HTLV-1-infected cell lines, whereas the effects of SIRT2 inhibition alone have not been elucidated. METHODS: We assessed the efficacy of our small molecule selective SIRT2 inhibitors NCO-90/141 to induce leukemic cell death. Cell viability was examined using the cell proliferation reagent Cell Count Reagent SF. Apoptotic cells were detected by annexin V-FITC and terminal deoxynucleotidyl transferase dUTP nick end labeling assays by flow cytometry. Caspase activity was detected using an APOPCYTO Intracellular Caspase Activity Detection Kit. The presence of autophagic vacuoles was assessed using a Cyto-ID Autophagy Detection Kit. RESULTS: Our novel small molecule SIRT2-specific inhibitors NCO-90/141 inhibited cell growth of leukemic cell lines including HTLV-1-transformed T-cells. NCO-90/141 induced apoptosis via caspase activation and mitochondrial superoxide generation in leukemic cell lines. However, a caspase inhibitor did not prevent this caspase-associated cell death. Interestingly, NCO-90/141 increased the LC3-II level together with autophagosome accumulation, indicating autophagic cell death. Thus, NCO-90/141 simultaneously caused apoptosis and autophagy. CONCLUSIONS: These results suggest that NCO-90/141 are highly effective against leukemic cells in caspase-dependent or -independent manners via autophagy, and they may have a novel therapeutic potential for treatment of leukemias including ATL.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Autophagy/drug effects , Histone Deacetylase Inhibitors/pharmacology , Leukemia/drug therapy , Sirtuin 2/antagonists & inhibitors , Caspases/metabolism , Cell Proliferation/drug effects , HL-60 Cells , Humans , Jurkat Cells , Leukemia/enzymology , Leukemia/pathology , Microtubule-Associated Proteins/metabolism , Mitochondria/drug effects , Mitochondria/enzymology , Mitochondria/pathology , Signal Transduction/drug effects , Sirtuin 2/metabolism , Superoxides/metabolismABSTRACT
Adult T cell leukemia/lymphoma (ATL) is an aggressive malignant T cell disease caused by human T cell leukemia virus-I (HTLV-1). Treatment outcomes for aggressive subtypes of ATL remain poor, with little improvement in overall survival since HTLV-1 was discovered. Therefore, new therapeutic strategies for ATL are required. STF-62247 induces autophagy and selectively kills renal cell carcinoma without apoptotic cell death. Here, we demonstrate that STF-62247 reduced cell viability and resulted in autophagosome accumulation and autophagy in leukemic cell lines (S1T, MT-2, and Jurkat). Interestingly, STF-62247 induced apoptosis in HTLV-1-infected cell lines (S1T and MT-2), as indicated by DNA fragmentation and caspase activation, but not in non-HTLV-1-infected Jurkat cells; a caspase inhibitor did not prevent this caspase-associated cell death. STF-62247 also increased nuclear endonuclease G levels. Furthermore, STF-62247 reduced cell viability and increased the number of apoptotic cells in peripheral blood mononuclear cells collected from patients with acute ATL, which has a poor prognosis. Therefore, STF-62247 may have novel therapeutic potential for ATL. This is the first evidence to demonstrate the cell growth-inhibitory effect of an autophagy inducer by caspase-dependent apoptosis and caspase-independent cell death via autophagy and endonuclease G in leukemic cells.
ABSTRACT
Germinal centers (GCs) in secondary lymphoid organs generate large numbers of apoptotic B cells that must be eliminated by phagocytes to prevent the development of autoimmune diseases. Although tingible body macrophages engulf apoptotic GC B cells, whether stromal cells are also involved in this process is unclear. In this study, we identified marginal reticular cells (MRCs) as novel nonprofessional phagocytes for the clearance of apoptotic GC B cells in the spleen. We used CD19eGFP (CD19creZ/EG) mice, which express enhanced GFP (eGFP) under the control of CD19cre expression, to track B cells in the GCs after immunization with NP-chicken γ globulin plus aluminum salt. We demonstrated that the MRC population, as determined by expression of podoplanin or Rankl, specifically showed an eGFP signal in the cytoplasm after immunization. These results suggest that MRCs contribute to the clearance of apoptotic B cells in GCs.
Subject(s)
Apoptosis/immunology , B-Lymphocytes/immunology , Germinal Center/immunology , Phagocytes/immunology , Animals , Autoimmune Diseases/immunology , Cytoplasm/immunology , Green Fluorescent Proteins/immunology , Macrophages/immunology , Mice , Mice, Inbred C57BL , Spleen/immunology , Stromal Cells/immunologyABSTRACT
Fc receptors play important roles for a wide array of immune responses. In contrast to the well-defined Fcγ and Fcε receptors, the molecular and functional characteristics of Fc receptors for IgA and IgM have remained incompletely understood for years. Recent progress has unveiled the characteristics of Fc receptors for IgA and IgM, including Fcα/µ receptor (Fcα/µR) (CD351), polymeric immunoglobulin receptor (poly-IgR), Fcα receptor (FcαRI) (CD89) and Fcµ receptor (FcµR). In this review, we summarize the molecular and functional characteristics of Fcα/µR in comparison with poly-IgR, FcµR and FcαRI, and focus particularly on the pro-inflammatory function of Fcα/µR expressed on marginal zone B cells in sepsis.
Subject(s)
B-Lymphocytes/immunology , Inflammation/immunology , Receptors, Fc/immunology , Receptors, Opioid, mu/immunology , Sepsis/immunology , Animals , HumansSubject(s)
Calcitonin/blood , Cellulitis/diagnosis , Fasciitis, Necrotizing/diagnosis , Aged , Biomarkers/blood , Cellulitis/blood , Diagnosis, Differential , Fasciitis, Necrotizing/blood , Female , Humans , Male , Middle Aged , Predictive Value of Tests , Retrospective Studies , Sensitivity and SpecificityABSTRACT
Follicular dendritic cells (FDCs) in lymphoid organs play an important role in the humoral immune response. However, because the isolation of FDCs is difficult due to their very small population size and fragility under mechanical and chemical stresses, the genetic and biochemical characteristics of FDCs remain unclear. Previously, we identified FDCs as ICAM-1+ cells in the CD45- non-hematopoietic cell fraction from naïve mouse spleen after cell separation by means of digestion with a combination of enzymes. In the present study, using a new combination of enzymes, we found that FDCs are highly enriched in the CD45-ICAM-1+CD21/35+ cell fraction. CD45-ICAM-1+CD21/35+ cells in the mouse spleen retained an antigen administered in vivo for more than 7 days. Moreover, CD45-ICAM-1+CD21/35+ cells isolated from the spleen of mice administered with a cognate antigen enhanced the survival and proliferation of antigen-specific B cells in vitro. Our improved protocol for the isolation of naïve FDCs will be useful for the analysis of FDCs in vitro and in vivo.
Subject(s)
Cell Separation/methods , Dendritic Cells, Follicular , Flow Cytometry/methods , Animals , Mice , Mice, Inbred C57BL , Real-Time Polymerase Chain ReactionABSTRACT
Adult T-cell leukemia/lymphoma (ATL), an aggressive T-cell malignancy that develops after long-term infection with human T-cell leukemia virus (HTLV-1), requires new treatments. Drug repositioning, reuse of a drug previously approved for the treatment of another condition to treat ATL, offers the possibility of reduced time and risk. Among clinically available angiotensin II receptor blockers, telmisartan is well known for its unique ability to activate peroxisome proliferator-activated receptor-γ, which plays various roles in lipid metabolism, cellular differentiation, and apoptosis. Here, telmisartan reduced cell viability and enhanced apoptotic cells via caspase activation in ex vivo peripheral blood monocytes from asymptomatic HTLV-1 carriers (ACs) or via caspase-independent cell death in acute-type ATL, which has a poor prognosis. Telmisartan also induced significant growth inhibition and apoptosis in leukemia cell lines via caspase activation, whereas other angiotensin II receptor blockers did not induce cell death. Interestingly, telmisartan increased the LC3-II-enriched protein fraction, indicating autophagosome accumulation and autophagy. Thus, telmisartan simultaneously caused caspase activation and autophagy. A hypertension medication with antiproliferation effects on primary and leukemia cells is intriguing. Patients with an early diagnosis of ATL are generally monitored until the disease progresses; thus, suppression of progression from AC and indolent ATL to acute ATL is important. Our results suggest that telmisartan is highly effective against primary cells and leukemia cell lines in caspase-dependent and -independent manners, and its clinical use may suppress acute transformation and improve prognosis of patients with this mortal disease. This is the first report demonstrating a cell growth-inhibitory effect of telmisartan in fresh peripheral blood mononuclear cells from leukemia patients.
ABSTRACT
Marginal zone (MZ) B cells produce a first wave of antibodies for protection from blood-borne pathogens. However, the role of MZ B cells in inflammatory responses has not been elucidated. Here we show that MZ B cells produce pro-inflammatory cytokines, such as interleukin-6 (IL-6), and exacerbate systemic inflammatory responses to lipopolysaccharide (LPS). After intravenous injection of LPS or E. coli, mice deficient in MZ B cells or IL-6 only in MZ B cells have attenuated systemic inflammatory responses and prolonged survival compared with wild-type mice. LPS directly stimulates MZ B cells via Toll-like receptor 4 (TLR4) and MyD88 pathways for IL-6 production. Furthermore, TLR4 requires physical and functional association with Fcα/µR (CD351) for its oligomer formation, NF-κB signalling and IL-6 production from MZ B cells; this association is responsible for systemic inflammatory responses and endotoxic shock. These results reveal a pro-inflammatory role of MZ B cells in endotoxic shock.
Subject(s)
B-Lymphocytes/metabolism , Interleukin-6/metabolism , Receptors, Fc/metabolism , Toll-Like Receptor 4/metabolism , Animals , B-Lymphocytes/drug effects , Escherichia coli Infections/physiopathology , Interleukin-6/genetics , Lipopolysaccharides/pharmacology , Mice, Inbred C3H , Mice, Inbred C57BL , Mice, Knockout , Myeloid Differentiation Factor 88/metabolism , NF-kappa B/metabolism , Receptors, Fc/genetics , Shock, Septic/physiopathology , Signal Transduction/drug effects , Signal Transduction/genetics , Toll-Like Receptor 4/geneticsABSTRACT
Epithelial tissues continually undergo apoptosis. Commensal organisms that inhabit the epithelium influence tissue homeostasis, in which regulatory T cells (Treg cells) have a central role. However, the physiological importance of epithelial cell apoptosis and how the number of Treg cells is regulated are both incompletely understood. Here we found that apoptotic epithelial cells negatively regulated the commensal-stimulated proliferation of Treg cells. Gut commensals stimulated CX3CR1(+)CD103(-)CD11b(+) dendritic cells (DCs) to produce interferon-ß (IFN-ß), which augmented the proliferation of Treg cells in the intestine. Conversely, phosphatidylserine exposed on apoptotic epithelial cells suppressed IFN-ß production by the DCs via inhibitory signaling mediated by the cell-surface glycoprotein CD300a and thus suppressed Treg cell proliferation. Our findings reveal a regulatory role for apoptotic epithelial cells in maintaining the number of Treg cell and tissue homeostasis.
Subject(s)
Apoptosis/immunology , Epidermis/immunology , Epithelial Cells/immunology , Gastrointestinal Microbiome/immunology , Interferon-beta/immunology , Intestinal Mucosa/immunology , Respiratory Mucosa/immunology , T-Lymphocytes, Regulatory/immunology , Allergens/toxicity , Animals , Colitis/chemically induced , Colitis/immunology , Colitis/pathology , Colon/cytology , Colon/immunology , Dendritic Cells/immunology , Dermatitis, Allergic Contact/etiology , Dermatitis, Allergic Contact/immunology , Dermatitis, Allergic Contact/pathology , Dextran Sulfate/toxicity , Epidermal Cells , Flow Cytometry , Immunohistochemistry , Intestinal Mucosa/cytology , Langerhans Cells/immunology , Lung/cytology , Lung/immunology , Mice , Mice, Knockout , Ovalbumin/toxicity , Real-Time Polymerase Chain Reaction , Receptors, Immunologic/genetics , Respiratory Mucosa/cytology , Salmonella Infections/immunology , Salmonella typhimuriumABSTRACT
We present the first case of dermatomyositis showing both vesicle formation and palmar papules. The association of bullous formation and internal malignancy, and palmar papules and interstitial lung disease (ILD) is well known in dermatomyositis, respectively. This patient presented with vesicles; however, the immunoprecipitation assays detected anti-MDA-5 antibody and the patient complicated rapidly progressive ILD, but no malignancy. We propose that palmar papules might be regarded as more critical than blister formation.
Subject(s)
Autoantibodies , Dermatomyositis , Interferon-Induced Helicase, IFIH1/immunology , Lung Diseases, Interstitial , Skin Diseases, Vesiculobullous , Autoantibodies/analysis , Autoantibodies/blood , Biopsy , Dermatomyositis/complications , Dermatomyositis/diagnosis , Dermatomyositis/immunology , Dermatomyositis/physiopathology , Disease Progression , Female , Hand , Humans , Lung Diseases, Interstitial/diagnosis , Lung Diseases, Interstitial/etiology , Lung Diseases, Interstitial/physiopathology , Middle Aged , Skin/pathology , Skin Diseases, Vesiculobullous/pathology , Skin Diseases, Vesiculobullous/physiopathologyABSTRACT
Microglia play an important role in receptor-mediated phagocytosis in the CNS. In brain abscess and other CNS infections, invading bacteria undergo opsonization with Igs or complement. Microglia recognize these opsonized pathogens by Fc or complement receptors triggering phagocytosis. In this study, we investigated the role of Fcα/µR, the less-studied receptor for IgM and IgA, in microglial phagocytosis. We showed that primary microglia, as well as N9 microglial cells, express Fcα/µR. We also showed that anti-Staphylococcus aureus IgM markedly increased the rate of microglial S. aureus phagocytosis. To unequivocally test the role of Fcα/µR in IgM-mediated phagocytosis, we performed experiments in microglia from Fcα/µR(-/-) mice. Surprisingly, we found that IgM-dependent phagocytosis of S. aureus was similar in microglia derived from wild-type or Fcα/µR(-/-) mice. We hypothesized that IgM-dependent activation of complement receptors might contribute to the IgM-mediated increase in phagocytosis. To test this, we used immunologic and genetic inactivation of complement receptor 3 components (CD11b and CD18) as well as C3. IgM-, but not IgG-mediated phagocytosis of S. aureus was reduced in wild-type microglia and macrophages following preincubation with an anti-CD11b blocking Ab. IgM-dependent phagocytosis of S. aureus was also reduced in microglia derived from CD18(-/-) and C3(-/-) mice. Taken together, our findings implicate complement receptor 3 and C3, but not Fcα/µR, in IgM-mediated phagocytosis of S. aureus by microglia.