RESUMO
Aging affects all cell types in the CNS and plays an important role in CNS diseases. However, the underlying molecular mechanisms driving these age-associated changes and their contribution to diseases are only poorly understood. The white matter in the aging brain as well as in diseases, such as Multiple sclerosis is characterized by subtle abnormalities in myelin sheaths and paranodes, suggesting that oligodendrocytes, the myelin-maintaining cells of the CNS, lose the capacity to preserve a proper myelin structure and potentially function in age and certain diseases. Here, we made use of directly converted oligodendrocytes (dchiOL) from young, adult and old human donors to study age-associated changes. dchiOL from all three age groups differentiated in an comparable manner into O4 + immature oligodendrocytes, but the proportion of MBP + mature dchiOL decreased with increasing donor age. This was associated with an increased ROS production and upregulation of cellular senescence markers such as CDKN1A, CDKN2A in old dchiOL. Comparison of the transcriptomic profiles of dchiOL from adult and old donors revealed 1324 differentially regulated genes with limited overlap with transcriptomic profiles of the donors' fibroblasts or published data sets from directly converted human neurons or primary rodent oligodendroglial lineage cells. Methylome analyses of dchiOL and human white matter tissue samples demonstrate that chronological and epigenetic age correlate in CNS white matter as well as in dchiOL and resulted in the identification of an age-specific epigenetic signature. Furthermore, we observed an accelerated epigenetic aging of the myelinated, normal appearing white matter of multiple sclerosis (MS) patients compared to healthy individuals. Impaired differentiation and upregulation of cellular senescence markers could be induced in young dchiOL in vitro using supernatants from pro-inflammatory microglia. In summary, our data suggest that physiological aging as well as inflammation-induced cellular senescence contribute to oligodendroglial pathology in inflammatory demyelinating diseases such as MS.
Assuntos
Envelhecimento , Senescência Celular , Esclerose Múltipla , Oligodendroglia , Humanos , Oligodendroglia/patologia , Oligodendroglia/metabolismo , Senescência Celular/fisiologia , Envelhecimento/patologia , Esclerose Múltipla/patologia , Esclerose Múltipla/metabolismo , Adulto , Idoso , Pessoa de Meia-Idade , Masculino , Feminino , Adulto Jovem , Inflamação/patologia , Inflamação/metabolismo , Substância Branca/patologia , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Inibidor de Quinase Dependente de Ciclina p21RESUMO
Frontotemporal dementia (FTD) is an incurable group of early-onset dementias that can be caused by the deposition of hyperphosphorylated tau in patient brains. However, the mechanisms leading to neurodegeneration remain largely unknown. Here, we combined single-cell analyses of FTD patient brains with a stem cell culture and transplantation model of FTD. We identified disease phenotypes in FTD neurons carrying the MAPT-N279K mutation, which were related to oxidative stress, oxidative phosphorylation, and neuroinflammation with an upregulation of the inflammation-associated protein osteopontin (OPN). Human FTD neurons survived less and elicited an increased microglial response after transplantation into the mouse forebrain, which we further characterized by single nucleus RNA sequencing of microdissected grafts. Notably, downregulation of OPN in engrafted FTD neurons resulted in improved engraftment and reduced microglial infiltration, indicating an immune-modulatory role of OPN in patient neurons, which may represent a potential therapeutic target in FTD.
Assuntos
Demência Frontotemporal , Neurônios , Osteopontina , Proteínas tau , Osteopontina/metabolismo , Osteopontina/genética , Demência Frontotemporal/genética , Demência Frontotemporal/patologia , Demência Frontotemporal/metabolismo , Humanos , Neurônios/metabolismo , Neurônios/patologia , Animais , Proteínas tau/metabolismo , Camundongos , Doenças Neuroinflamatórias/metabolismo , Doenças Neuroinflamatórias/patologia , Microglia/metabolismo , Microglia/patologia , Mutação/genéticaRESUMO
Oligodendrocyte (OL) injury and loss are central features of evolving lesions in multiple sclerosis. Potential causative mechanisms of OL loss include metabolic stress within the lesion microenvironment. Here we use the injury response of primary human OLs (hOLs) to metabolic stress (reduced glucose/nutrients) in vitro to help define the basis for the in situ features of OLs in cases of MS. Under metabolic stress in vitro, we detected reduction in ATP levels per cell that precede changes in survival. Autophagy was initially activated, although ATP levels were not altered by inhibitors (chloroquine) or activators (Torin-1). Prolonged stress resulted in autophagy failure, documented by non-fusion of autophagosomes and lysosomes. Consistent with our in vitro results, we detected higher expression of LC3, a marker of autophagosomes in OLs, in MS lesions compared to controls. Both in vitro and in situ, we observe a reduction in nuclear size of remaining OLs. Prolonged stress resulted in increased ROS and cleavage of spectrin, a target of Ca2+-dependent proteases. Cell death was however not prevented by inhibitors of ferroptosis or MPT-driven necrosis, the regulated cell death (RCD) pathways most likely to be activated by metabolic stress. hOLs have decreased expression of VDAC1, VDAC2, and of genes regulating iron accumulation and cyclophilin. RNA sequencing analyses did not identify activation of these RCD pathways in vitro or in MS cases. We conclude that this distinct response of hOLs, including resistance to RCD, reflects the combined impact of autophagy failure, increased ROS, and calcium influx, resulting in metabolic collapse and degeneration of cellular structural integrity. Defining the basis of OL injury and death provides guidance for development of neuro-protective strategies.
Assuntos
Esclerose Múltipla Crônica Progressiva , Esclerose Múltipla , Humanos , Esclerose Múltipla/patologia , Espécies Reativas de Oxigênio/metabolismo , Oligodendroglia/patologia , Morte Celular , Esclerose Múltipla Crônica Progressiva/patologia , Trifosfato de Adenosina/metabolismoRESUMO
The adult brain retains over life endogenous neural stem/precursor cells (eNPCs) within the subventricular zone (SVZ). Whether or not these cells exert physiological functions is still unclear. In the present work, we provide evidence that SVZ-eNPCs tune structural, electrophysiological, and behavioural aspects of striatal function via secretion of insulin-like growth factor binding protein-like 1 (IGFBPL1). In mice, selective ablation of SVZ-eNPCs or selective abrogation of IGFBPL1 determined an impairment of striatal medium spiny neuron morphology, a higher failure rate in GABAergic transmission mediated by fast-spiking interneurons, and striatum-related behavioural dysfunctions. We also found IGFBPL1 expression in the human SVZ, foetal and induced-pluripotent stem cell-derived NPCs. Finally, we found a significant correlation between SVZ damage, reduction of striatum volume, and impairment of information processing speed in neurological patients. Our results highlight the physiological role of adult SVZ-eNPCs in supporting cognitive functions by regulating striatal neuronal activity.
Assuntos
Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Ventrículos Laterais , Células-Tronco Neurais , Proteínas Supressoras de Tumor , Animais , Humanos , Camundongos , Eletrofisiologia Cardíaca , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/fisiologia , Células-Tronco Neurais/fisiologia , Proteínas Supressoras de Tumor/fisiologia , Ventrículos Laterais/fisiologiaRESUMO
Although major progress in multiple sclerosis research has been made during the last decades, key questions related to the cause and the mechanisms of brain and spinal cord pathology remain unresolved. These cover a broad range of topics, including disease aetiology, antigenic triggers of the immune response inside and/or outside the CNS and mechanisms of inflammation, demyelination neurodegeneration and tissue repair. Most of these questions can be addressed with novel molecular technologies in the injured CNS. Access to brain and spinal cord tissue from multiple sclerosis patients is, therefore, of critical importance. High-quality tissue is provided in part by the existing brain banks. However, material from early and highly active disease stages is limited. An initiative, realized under the patronage of the European Charcot Foundation, gathered together experts from different disciplines to analyse the current state of multiple sclerosis tissues collected post-mortem or as biopsies. Here, we present an account of what material is currently available and where it can be accessed. We also provide recommendations on how tissue donation from patients in early disease stages could be potentially increased and for procedures of tissue sampling and preservation. We also suggest to create a registry of the available tissues that, depending on the source (autopsy versus biopsy), could be made accessible to clinicians and researchers.
RESUMO
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that drive the cell fate decisions towards conventional (Tconv) or regulatory T cells (Treg). Following TCR activation, intracellular calcium (Ca2+) is the most important second messenger, for which the potassium channel K2P18.1 is a relevant regulator. Here, we identify K2P18.1 as a central translator of the TCR signal into the thymus-derived Treg (tTreg) selection process. TCR signal was coupled to NF-κB-mediated K2P18.1 upregulation in tTreg progenitors. K2P18.1 provided the driving force for sustained Ca2+ influx that facilitated NF-κB- and NFAT-dependent expression of FoxP3, the master transcription factor for Treg development and function. Loss of K2P18.1 ion-current function induced a mild lymphoproliferative phenotype in mice, with reduced Treg numbers that led to aggravated experimental autoimmune encephalomyelitis, while a gain-of-function mutation in K2P18.1 resulted in increased Treg numbers in mice. Our findings in human thymus, recent thymic emigrants and multiple sclerosis patients with a dominant-negative missense K2P18.1 variant that is associated with poor clinical outcomes indicate that K2P18.1 also plays a role in human Treg development. Pharmacological modulation of K2P18.1 specifically modulated Treg numbers in vitro and in vivo. Finally, we identified nitroxoline as a K2P18.1 activator that led to rapid and reversible Treg increase in patients with urinary tract infections. Conclusively, our findings reveal how K2P18.1 translates TCR signals into thymic T cell fate decisions and Treg development, and provide a basis for the therapeutic utilization of Treg in several human disorders.
Assuntos
Canais de Potássio , Receptores de Antígenos de Linfócitos T , Linfócitos T Reguladores , Animais , Diferenciação Celular , Fatores de Transcrição Forkhead , Humanos , Camundongos , NF-kappa B , Timócitos , TimoRESUMO
G-protein-coupled receptors (GPCRs), especially chemokine receptors, play a central role in the regulation of T cell migration. Various GPCRs are upregulated in activated CD4 T cells, including P2Y10, a putative lysophospholipid receptor that is officially still considered an orphan GPCR, i.e., a receptor with unknown endogenous ligand. Here we show that in mice lacking P2Y10 in the CD4 T cell compartment, the severity of experimental autoimmune encephalomyelitis and cutaneous contact hypersensitivity is reduced. P2Y10-deficient CD4 T cells show normal activation, proliferation and differentiation, but reduced chemokine-induced migration, polarization, and RhoA activation upon in vitro stimulation. Mechanistically, CD4 T cells release the putative P2Y10 ligands lysophosphatidylserine and ATP upon chemokine exposure, and these mediators induce P2Y10-dependent RhoA activation in an autocrine/paracrine fashion. ATP degradation impairs RhoA activation and migration in control CD4 T cells, but not in P2Y10-deficient CD4 T cells. Importantly, the P2Y10 pathway appears to be conserved in human T cells. Taken together, P2Y10 mediates RhoA activation in CD4 T cells in response to auto-/paracrine-acting mediators such as LysoPS and ATP, thereby facilitating chemokine-induced migration and, consecutively, T cell-mediated diseases.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Encefalomielite Autoimune Experimental/imunologia , Esclerose Múltipla/imunologia , Receptores Purinérgicos P2Y/metabolismo , Receptores Purinérgicos P2/metabolismo , Trifosfato de Adenosina/metabolismo , Adulto , Idoso , Animais , Comunicação Autócrina/imunologia , Linfócitos T CD4-Positivos/metabolismo , Estudos de Casos e Controles , Células Cultivadas , Quimiocinas/metabolismo , Quimiotaxia de Leucócito/imunologia , Encefalomielite Autoimune Experimental/sangue , Feminino , Técnicas de Silenciamento de Genes , Técnicas de Inativação de Genes , Humanos , Lisofosfolipídeos/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Esclerose Múltipla/sangue , Comunicação Parácrina/imunologia , Cultura Primária de Células , Receptores Purinérgicos P2/genética , Receptores Purinérgicos P2Y/genética , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
Generation of induced oligodendrocyte progenitor cells (iOPCs) from somatic fibroblasts is a strategy for cell-based therapy of myelin diseases. However, iOPC generation is inefficient, and the resulting iOPCs exhibit limited expansion and differentiation competence. Here we overcome these limitations by transducing an optimized transcription factor combination into a permissive donor phenotype, the pericyte. Pericyte-derived iOPCs (PC-iOPCs) are stably expandable and functionally myelinogenic with high differentiation competence. Unexpectedly, however, we found that PC-iOPCs are metastable so that they can produce myelination-competent oligodendrocytes or revert to their original identity in a context-dependent fashion. Phenotypic reversion of PC-iOPCs is tightly linked to memory of their original transcriptome and epigenome. Phenotypic reversion can be disconnected from this donor cell memory effect, and in vivo myelination can eventually be achieved by transplantation of O4+ pre-oligodendrocytes. Our data show that donor cell source and memory can contribute to the fate and stability of directly converted cells.
Assuntos
Bainha de Mielina , Oligodendroglia , Diferenciação Celular , Fibroblastos , Células-TroncoRESUMO
OBJECTIVE: To determine whether B-cell presence in brainstem and white matter (WM) lesions is associated with poorer pathological and clinical characteristics in advanced MS autopsy cases. METHODS: Autopsy tissue of 140 MS and 24 control cases and biopsy tissue of 24 patients with MS were examined for CD20+ B cells and CD138+ plasma cells. The presence of these cells was compared with pathological and clinical characteristics. In corresponding CSF and plasma, immunoglobulin (Ig) G ratio and oligoclonal band (OCB) patterns were determined. In a clinical cohort of 73 patients, the presence of OCBs was determined during follow-up and compared to status at diagnosis. RESULTS: In 34% of active and 71% of mixed active/inactive lesions, B cells were absent, which correlated with less pronounced meningeal B-cell infiltration (p < 0.0001). The absence of B cells and plasma cells in brainstem and WM lesions was associated with a longer disease duration (p = 0.001), less frequent secondary progressive MS compared with relapsing and primary progressive MS (p < 0.0001 and p = 0.046, respectively), a lower proportion of mixed active/inactive lesions (p = 0.01), and less often perivascular T-cell clustering (p < 0.0001). Moreover, a lower CSF IgG ratio (p = 0.006) and more frequent absence of OCBs (p < 0.0001) were noted. In a clinical cohort, numbers of patients without OCBs in CSF were increased at follow-up (27.4%). CONCLUSIONS: The absence of B cells is associated with a favorable clinical and pathological profile. This finding may reflect extremes of a continuum of genetic or environmental constitution, but also a regression of WM humoral immunopathology in the natural course of advanced MS.
Assuntos
Linfócitos B/metabolismo , Tronco Encefálico/metabolismo , Esclerose Múltipla/metabolismo , Bandas Oligoclonais/metabolismo , Índice de Gravidade de Doença , Substância Branca/metabolismo , Adulto , Idoso , Tronco Encefálico/patologia , Estudos de Casos e Controles , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/patologia , Substância Branca/patologiaRESUMO
Oligodendrocytes are extensively coupled to astrocytes, a phenomenon ensuring glial homeostasis and maintenance of central nervous system myelin. Molecular disruption of this communication occurs in demyelinating diseases such as multiple sclerosis. Less is known about the vulnerability and reconstruction of the panglial network during adult demyelination-remyelination. Here, we took advantage of lysolcithin-induced demyelination to investigate the expression dynamics of the oligodendrocyte specific connexin 47 (Cx47) and to some extent that of astrocyte Cx43, and whether this dynamic could be modulated by grafted induced pluripotent stem cell (iPSC)-neural progeny. Our data show that disruption of Cx43-Cx47 mediated hetero-cellular gap-junction intercellular communication following demyelination is larger in size than demyelination. Loss of Cx47 expression is timely rescued during remyelination and accelerated by the grafted neural precursors. Moreover, mouse and human iPSC-derived oligodendrocytes express Cx47, which co-labels with astrocyte Cx43, indicating their integration into the panglial network. These data suggest that in rodents, full lesion repair following transplantation occurs by panglial reconstruction in addition to remyelination. Targeting panglial elements by cell therapy or pharmacological compounds may help accelerating or stabilizing re/myelination in myelin disorders.
Assuntos
Conexinas , Células-Tronco Pluripotentes Induzidas , Esclerose Múltipla , Remielinização , Animais , Astrócitos , Conexina 43/genética , Camundongos , OligodendrogliaRESUMO
Oligodendroglial pathology is central to de- and dysmyelinating, but also contributes to neurodegenerative and psychiatric diseases as well as brain injury. The understanding of oligodendroglial biology in health and disease has been significantly increased during recent years by experimental in vitro and in vivo preclinical studies as well as histological analyses of human tissue samples. However, for many of these diseases the underlying pathology is still not fully understood and treatment options are frequently lacking. This is at least partly caused by the limited access to human oligodendrocytes from patients to perform functional studies and drug screens. The induced pluripotent stem cell technology (iPSC) represents a possibility to circumvent this obstacle and paves new ways to study human disease and to develop new treatment options for so far incurable central nervous system (CNS) diseases. In this review, we summarize the differences between human and rodent oligodendrocytes, provide an overview of the different techniques to generate oligodendrocytes from human progenitor or stem cells and describe the results from studies using iPSC derived oligodendroglial lineage cells. Furthermore, we discuss future perspectives and challenges of the iPSC technology with respect to disease modeling, drug screen, and cell transplantation approaches.
Assuntos
Doenças Desmielinizantes/patologia , Células-Tronco Pluripotentes Induzidas/patologia , Leucoencefalopatias/patologia , Oligodendroglia/patologia , Diferenciação Celular/fisiologia , HumanosRESUMO
The tightly controlled processes of myelination and remyelination require the participation of the cytoskeleton. The reorganization of the cytoskeleton is controlled by small GTPases of the RhoA family. Here, we report that Vav3, a Rho GTPase regulating guanine nucleotide exchange factor (GEF) is involved in oligodendrocyte maturation, myelination and remyelination. When Vav3 was eliminated by genetic recombination, oligodendrocyte precursor cell (OPC) differentiation toward mature oligodendrocytes was accelerated. In contrast, Vav3-deficient oligodendrocytes displayed a reduced capacity to myelinate synthetic microfibers in vitro. Furthermore, remyelination was impaired in Vav3 knockout cerebellar slice cultures that were demyelinated by the addition of lysolecithin. In agreement with these observations, remyelination was compromised when the cuprizone model of myelin lesion was performed in Vav3-deficient mice. When Vav3-deficient oligodendrocytes were examined with Förster resonance energy transfer (FRET)-based biosensors, an altered activation profile of RhoA GTPases was revealed on the cellular level, which could be responsible for an impaired remyelination. Taken together, this study highlights Vav3 as a novel regulator of oligodendrocyte maturation and remyelination, suggesting that manipulation of the Vav3-dependent signaling pathway could help to improve myelin repair.
Assuntos
Diferenciação Celular/genética , Leucoencefalopatias/patologia , Células Precursoras de Oligodendrócitos/fisiologia , Proteínas Proto-Oncogênicas c-vav/metabolismo , Remielinização/genética , Animais , Caspase 3/metabolismo , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Quelantes/toxicidade , Cuprizona/toxicidade , Modelos Animais de Doenças , GTP Fosfo-Hidrolases/metabolismo , Antígeno Ki-67/metabolismo , Leucoencefalopatias/induzido quimicamente , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Básica da Mielina/metabolismo , Fibras Nervosas Mielinizadas/patologia , Células Precursoras de Oligodendrócitos/patologia , Técnicas de Cultura de Órgãos , Proteínas Proto-Oncogênicas c-vav/genética , Remielinização/efeitos dos fármacos , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
Multiple sclerosis (MS) patients exhibit neuropsychological symptoms in early disease despite the immune attack occurring predominantly in white matter and spinal cord. It is unclear why neurodegeneration may start early in the disease and is prominent in later stages. We assessed cortical microcircuit activity by employing spiking-specific two-photon Ca2+ imaging in proteolipid protein-immunized relapsing-remitting SJL/J mice in vivo. We identified the emergence of hyperactive cortical neurons in remission only, independent of direct immune-mediated damage and paralleled by elevated anxiety. High levels of neuronal activity were accompanied by increased caspase-3 expression. Cortical TNFα expression was mainly increased by excitatory neurons in remission; blockade with intraventricular infliximab restored AMPA spontaneous excitatory postsynaptic current frequencies, completely recovered normal neuronal network activity patterns and alleviated elevated anxiety. This suggests a dysregulation of cortical networks attempting to achieve functional compensation by synaptic plasticity mechanisms, indicating a link between immune attack and early start of neurodegeneration.
Assuntos
Córtex Cerebral/fisiopatologia , Encefalomielite Autoimune Experimental/complicações , Encefalomielite Autoimune Experimental/patologia , Hipercinese/etiologia , Recuperação de Função Fisiológica/fisiologia , Animais , Anti-Inflamatórios não Esteroides/uso terapêutico , Carbazóis/uso terapêutico , Células Cultivadas , Córtex Cerebral/ultraestrutura , Cuprizona/toxicidade , Modelos Animais de Doenças , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacocinética , Encefalomielite Autoimune Experimental/induzido quimicamente , Encefalomielite Autoimune Experimental/tratamento farmacológico , Antagonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Adjuvante de Freund/toxicidade , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/genética , Camundongos , Camundongos Transgênicos , Microglia/patologia , Proteína Proteolipídica de Mielina/toxicidade , Fragmentos de Peptídeos/toxicidade , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo , Quinoxalinas/farmacologia , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologiaRESUMO
The bone morphogenetic protein (BMP) type I receptors ALK2 and ALK3 are essential for expression of hepcidin, a key iron regulatory hormone. In mice, hepatocyte-specific Alk2 deficiency leads to moderate iron overload with periportal liver iron accumulation, while hepatocyte-specific Alk3 deficiency leads to severe iron overload with centrilobular liver iron accumulation and a more marked reduction of basal hepcidin levels. The objective of this study was to investigate whether the two receptors have additive roles in hepcidin regulation. Iron overload in mice with hepatocyte-specific Alk2 and Alk3 (Alk2/3) deficiency was characterized and compared to hepatocyte-specific Alk3 deficient mice. Co-immunoprecipitation studies were performed to detect the formation of ALK2 and ALK3 homodimer and heterodimer complexes in vitro in the presence and absence of ligands. The iron overload phenotype of hepatocyte-specific Alk2/3-deficient mice was more severe than that of hepatocyte-specific Alk3-deficient mice. In vitro co-immunoprecipitation studies in Huh7 cells showed that ALK3 can homodimerize in absence of BMP2 or BMP6. In contrast, ALK2 did not homodimerize in either the presence or absence of BMP ligands. However, ALK2 did form heterodimers with ALK3 in the presence of BMP2 or BMP6. ALK3-ALK3 and ALK2-ALK3 receptor complexes induced hepcidin expression in Huh7 cells. Our data indicate that: (I) ALK2 and ALK3 have additive functions in vivo, as Alk2/3 deficiency leads to a greater degree of iron overload than Alk3 deficiency; (II) ALK3, but not ALK2, undergoes ligand-independent homodimerization; (III) the formation of ALK2-ALK3 heterodimers is ligand-dependent and (IV) both receptor complexes functionally induce hepcidin expression in vitro.
Assuntos
Receptores de Ativinas Tipo I/genética , Proteína Morfogenética Óssea 2/genética , Proteína Morfogenética Óssea 6/genética , Receptores de Proteínas Morfogenéticas Ósseas Tipo I/genética , Hepcidinas/genética , Sobrecarga de Ferro/genética , Ferro/metabolismo , Receptores de Ativinas Tipo I/deficiência , Animais , Proteína Morfogenética Óssea 2/metabolismo , Proteína Morfogenética Óssea 6/metabolismo , Receptores de Proteínas Morfogenéticas Ósseas Tipo I/deficiência , Linhagem Celular Tumoral , Feminino , Regulação da Expressão Gênica , Hepatócitos/metabolismo , Hepatócitos/patologia , Hepcidinas/metabolismo , Humanos , Sobrecarga de Ferro/metabolismo , Sobrecarga de Ferro/patologia , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Ligação Proteica , Multimerização Proteica , Índice de Gravidade de Doença , Transdução de SinaisRESUMO
BACKGROUND: Very late antigen 4 (VLA-4; integrin α4ß1) is critical for transmigration of T helper (TH) 1 cells into the central nervous system (CNS) under inflammatory conditions such as multiple sclerosis (MS). We have previously shown that VLA-4 and melanoma cell adhesion molecule (MCAM) are important for trans-endothelial migration of human TH17 cells in vitro and here investigate their contribution to pathogenic CNS inflammation. METHODS: Antibody blockade of VLA-4 and MCAM is assessed in murine models of CNS inflammation in conjunction with conditional ablation of α4-integrin expression in T cells. Effects of VLA-4 and MCAM blockade on lymphocyte migration are further investigated in the human system via in vitro T cell transmigration assays. RESULTS: Compared to the broad effects of VLA-4 blockade on encephalitogenic T cell migration over endothelial barriers, MCAM blockade impeded encephalitogenic T cell migration in murine models of MS that especially depend on CNS migration across the choroid plexus (CP). In transgenic mice lacking T cell α4-integrin expression (CD4::Itga4-/-), MCAM blockade delayed disease onset. Migration of MCAM-expressing T cells through the CP into the CNS was restricted, where laminin 411 (composed of α4, ß1, γ1 chains), the proposed major ligand of MCAM, is detected in the endothelial basement membranes of murine CP tissue. This finding was translated to the human system; blockade of MCAM with a therapeutic antibody reduced in vitro transmigration of MCAM-expressing T cells across a human fibroblast-derived extracellular matrix layer and a brain-derived endothelial monolayer, both expressing laminin α4. Laminin α4 was further detected in situ in CP endothelial-basement membranes in MS patients' brain tissue. CONCLUSIONS: Our findings suggest that MCAM-laminin 411 interactions facilitate trans-endothelial migration of MCAM-expressing T cells into the CNS, which seems to be highly relevant to migration via the CP and to potential future clinical applications in neuroinflammatory disorders.
Assuntos
Antígeno CD146/metabolismo , Plexo Corióideo/patologia , Encefalomielite Autoimune Experimental/patologia , Linfócitos T/efeitos dos fármacos , Animais , Anticorpos/uso terapêutico , Antígeno CD146/imunologia , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Células Cultivadas , Sistema Nervoso Central/patologia , Plexo Corióideo/diagnóstico por imagem , Plexo Corióideo/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/induzido quimicamente , Células Endoteliais/efeitos dos fármacos , Adjuvante de Freund/toxicidade , Humanos , Integrina alfa4beta1/genética , Integrina alfa4beta1/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Glicoproteína Mielina-Oligodendrócito/toxicidade , Fragmentos de Peptídeos/toxicidade , Proteínas Quinases/genética , Proteínas Quinases/metabolismoRESUMO
T cells critically depend on reprogramming of metabolic signatures to meet the bioenergetic demands during activation and clonal expansion. Here we identify the transcription factor Nur77 as a cell-intrinsic modulator of T cell activation. Nur77-deficient T cells are highly proliferative, and lack of Nur77 is associated with enhanced T cell activation and increased susceptibility for T cell-mediated inflammatory diseases, such as CNS autoimmunity, allergic contact dermatitis and collagen-induced arthritis. Importantly, Nur77 serves as key regulator of energy metabolism in T cells, restricting mitochondrial respiration and glycolysis and controlling switching between different energy pathways. Transcriptional network analysis revealed that Nur77 modulates the expression of metabolic genes, most likely in close interaction with other transcription factors, especially estrogen-related receptor α. In summary, we identify Nur77 as a transcriptional regulator of T cell metabolism, which elevates the threshold for T cell activation and confers protection in different T cell-mediated inflammatory diseases.
Assuntos
Autoimunidade , Ativação Linfocitária , Mitocôndrias , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares , Consumo de Oxigênio/imunologia , Linfócitos T , Animais , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/metabolismo , Perfilação da Expressão Gênica , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/imunologia , Mitocôndrias/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/imunologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Receptores de Estrogênio/genética , Receptores de Estrogênio/imunologia , Receptores de Estrogênio/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Receptor ERRalfa Relacionado ao EstrogênioRESUMO
Investigations into brain function and disease depend on the precise classification of neural cell types. Cells of the oligodendrocyte lineage differ greatly in their morphology, but accurate identification has thus far only been possible for oligodendrocyte progenitor cells and mature oligodendrocytes in humans. We find that breast carcinoma amplified sequence 1 (BCAS1) expression identifies an oligodendroglial subpopulation in the mouse and human brain. These cells are newly formed, myelinating oligodendrocytes that segregate from oligodendrocyte progenitor cells and mature oligodendrocytes and mark regions of active myelin formation in development and in the adult. We find that BCAS1+ oligodendrocytes are restricted to the fetal and early postnatal human white matter but remain in the cortical gray matter until old age. BCAS1+ oligodendrocytes are reformed after experimental demyelination and found in a proportion of chronic white matter lesions of patients with multiple sclerosis (MS) even in a subset of patients with advanced disease. Our work identifies a means to map ongoing myelin formation in health and disease and presents a potential cellular target for remyelination therapies in MS.
Assuntos
Esclerose Múltipla/metabolismo , Proteínas de Neoplasias/metabolismo , Oligodendroglia/metabolismo , Animais , Doenças Desmielinizantes , Humanos , Camundongos , Esclerose Múltipla/patologia , Bainha de Mielina/metabolismoRESUMO
BACKGROUND: The nuclear receptor farnesoid-X-receptor (FXR; NR1H4) is expressed not only in the liver, gut, kidney and adipose tissue but also in the immune cells. FXR has been shown to confer protection in several animal models of inflammation, including experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). FXR agonists are currently tested in clinical trials for treatment of human metabolic diseases. The beneficial effect of FXR agonists in EAE suggests that FXR might represent a potential target in inflammatory-demyelinating CNS diseases, such as MS. In MS, oligodendrocytes not only undergo cell death but also contribute to remyelination. This repair mechanism is impaired due to a differentiation block of oligodendroglial progenitor cells. Activation of other nuclear receptors that heterodimerize with FXR promote oligodendroglial differentiation. Therefore, we wanted to address the functional relevance of FXR for glial cells, especially for oligodendroglial differentiation. METHODS: We isolated primary murine oligodendrocytes from FXR-deficient (FXR Ko) and wild-type (WT) mice and determined the effect of FXR deficiency and activation on oligodendroglial differentiation by analysing markers of oligodendroglial progenitor cells (OPCs) and mature oligodendrocytes (OLs) using qRT-PCR and immunocytochemistry. Additionally, we determined whether FXR activation modulates the pro-inflammatory profile of astrocytes or microglia and whether this may subsequently modulate oligodendroglial differentiation. These in vitro studies were complemented by histological analyses of oligodendrocytes in FXR Ko mice. RESULTS: FXR is expressed by OPCs and mature oligodendrocytes. However, lack of FXR did not affect oligodendroglial differentiation in vitro or in vivo. Furthermore, activation of FXR using the synthetic agonist GW4064 did not affect oligodendroglial differentiation, remyelination in an ex vivo model or the expression of pro-inflammatory molecules in astrocytes or microglia. Concordantly, no effects of supernatants from macrophages cultured in the presence of GW4064 were observed regarding a possible indirect impact on oligodendroglial differentiation. CONCLUSIONS: Our data suggest that FXR is dispensable for oligodendroglial differentiation and that FXR agonists, such as GW4064, represent a potential therapeutic approach for MS which specifically targets peripheral immune cells including macrophages but not brain-resident cells, such as oligodendrocytes, astrocytes or microglia.
Assuntos
Oligodendroglia/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células Cultivadas , Cerebelo/citologia , Citocinas/genética , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Técnicas In Vitro , Isoxazóis/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Básica da Mielina/genética , Proteína Básica da Mielina/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Óxido Nítrico/metabolismo , Proteínas Nogo/metabolismo , Fator de Transcrição 2 de Oligodendrócitos , Oligodendroglia/efeitos dos fármacos , RNA Mensageiro/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Multiple sclerosis is a complex and heterogeneous, most likely autoimmune, demyelinating disease of the central nervous system (CNS). Although a number of histological classification systems for CNS lesions have been used by different groups in recent years, no uniform classification exists. In this paper, we propose a simple and unifying classification of MS lesions incorporating many elements of earlier histological systems that aims to provide guidelines for neuropathologists and researchers studying MS lesions to allow for better comparison of different studies performed with MS tissue, and to aid in understanding the pathogenesis of the disease. Based on the presence/absence and distribution of macrophages/microglia (inflammatory activity) and the presence/absence of ongoing demyelination (demyelinating activity), we suggest differentiating between active, mixed active/inactive, and inactive lesions with or without ongoing demyelination. Active lesions are characterized by macrophages/microglia throughout the lesion area, whereas mixed active/inactive lesions have a hypocellular lesion center with macrophages/microglia limited to the lesion border. Inactive lesions are almost completely lacking macrophages/microglia. Active and mixed active/inactive lesions can be further subdivided into lesions with ongoing myelin destruction (demyelinating lesions) and lesions in which the destruction of myelin has ceased, but macrophages are still present (post-demyelinating lesions). This distinction is based on the presence or absence of myelin degradation products within the cytoplasm of macrophages/microglia. For this classification of MS lesions, identification of myelin with histological stains [such as luxol fast blue-PAS] or by immunohistochemistry using antibodies against myelin basic-protein (MBP) or proteolipid-protein (PLP), as well as, detection of macrophages/microglia by, e.g., anti-CD68 is sufficient. Active and demyelinating lesions may be further subdivided into the early and late demyelinating lesions. The former is defined by the presence in macrophages of major and small molecular weight myelin proteins, such as cyclic nucleotide diphosphoesterase (CNP), myelin oligodendrocyte glycoprotein (MOG), or myelin-associated protein (MAG), whereas macrophages in the latter demonstrate merely the presence of the major myelin proteins MBP or PLP. We discuss the histological features and staining techniques required to classify MS lesions, and, in addition, describe the histological hallmarks of cortical pathology and diffuse white matter changes, as well as of remyelination.
Assuntos
Esclerose Múltipla/classificação , Esclerose Múltipla/patologia , Animais , Humanos , Macrófagos/imunologia , Macrófagos/patologia , Microglia/imunologia , Microglia/patologia , Esclerose Múltipla/diagnóstico por imagem , Esclerose Múltipla/imunologia , Substância Branca/diagnóstico por imagem , Substância Branca/imunologia , Substância Branca/patologiaRESUMO
Intravenous iron supplementation is an effective therapy in iron deficiency anemia (IDA), but controversial in anemia of inflammation (AI). Unbound iron can be used by bacteria and viruses for their replication and enhance the inflammatory response. Nowadays available high molecular weight iron complexes for intravenous iron substitution, such as ferric carboxymaltose, might be useful in AI, as these pharmaceuticals deliver low doses of free iron over a prolonged period of time. We tested the effects of intravenous iron carboxymaltose in murine AI: Wild-type mice were exposed to the heat-killed Brucella abortus (BA) model and treated with or without high molecular weight intravenous iron. 4h after BA injection followed by 2h after intravenous iron treatment, inflammatory cytokines were upregulated by BA, but not enhanced by iron treatment. In long term experiments, mice were fed a regular or an iron deficient diet and then treated with intravenous iron or saline 14 days after BA injection. Iron treatment in mice with BA-induced AI was effective 24h after iron administration. In contrast, mice with IDA (on iron deficiency diet) prior to BA-IA required 7d to recover from AI. In these experiments, inflammatory markers were not further induced in iron-treated compared to vehicle-treated BA-injected mice. These results demonstrate that intravenous iron supplementation effectively treated the murine BA-induced AI without further enhancement of the inflammatory response. Studies in humans have to reveal treatment options for AI in patients.