RESUMO
Microglial activation has been widely demonstrated to mediate inflammatory processes that are crucial in several neurodegenerative disorders. Pharmaceuticals that can deliver direct inhibitory effects on microglia are therefore considered as a potential strategy to counter balance neurodegenerative progression. Caffeic acid phenethyl ester (CAPE), a natural phenol in honeybee propolis, is known to possess antioxidant, anti-inflammatory and anti-microbial properties. Accordingly, the current study intended to probe the effects of CAPE on microglia activation by using in vitro and in vivo models. Western blot and Griess reaction assay revealed CAPE significantly inhibited the expressions of inducible nitric oxide synthase (NOS), cyclooxygenase (COX)-2 and the production of nitric oxide (NO). Administration of CAPE resulted in increased expressions of hemeoxygenase (HO)-1and erythropoietin (EPO) in microglia. The phosphorylated adenosine monophosphate-activated protein kinase (AMPK)-α was further found to regulate the anti-inflammatory effects of caffeic acid. In vivo results from immunohistochemistry along with rotarod test also revealed the anti-neuroinflammatory effects of CAPE in microglia activation. The current study has evidenced several possible molecular determinants, AMPKα, EPO, and HO-1, in mediating anti-neuroinflammatory responses in microglial cells.
Assuntos
Ácidos Cafeicos/farmacologia , Microglia/efeitos dos fármacos , Álcool Feniletílico/análogos & derivados , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Linhagem Celular , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Eritropoetina/genética , Eritropoetina/metabolismo , Heme Oxigenase-1/genética , Heme Oxigenase-1/metabolismo , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Microglia/metabolismo , Microglia/patologia , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Álcool Feniletílico/farmacologiaRESUMO
Glioblastoma multiforme (GBM) is the most common and lethal type of primary brain tumor characterized by its rapid infiltration to surrounding tissues during the early stages. The fast spreading of GBM obscures the initiation of the tumor mass making the treatment outcome undesirable. Endothelin-1 is known as a secretory protein presented in various types of brain cells, which has been indicated as a factor for cancer pathology. The aim of the present study was to investigate the molecular mechanism of cell migration in GBM. We found that various malignant glioma cells expressed higher amounts of endothelin-1, ETA, and ETB receptors than nonmalignant human astrocytes. The application of endothelin-1 enhanced the migratory activity in human U251 glioma cells corresponding to increased expression of matrix metalloproteinase (MMP)-9 and MMP-13. The endothelin-1-induced cell migration was attenuated by MMP-9 and MMP-13 inhibitors and inhibitors of mitogen-activated protein (MAP) kinase and PI3 kinase/Akt. Furthermore, the elevated levels of phosphate c-Jun accumulation in the nucleus and activator protein-1 (AP-1)-DNA binding activity were also found in endothelin-1 treated glioma cells. In migration-prone sublines, cells with greater migration ability showed higher endothelin-1, ETB receptor, and MMP expressions. These results indicate that endothelin-1 activates MAP kinase and AP-1 signaling, resulting in enhanced MMP-9 and MMP-13 expressions and cell migration in GBM.
Assuntos
Movimento Celular/fisiologia , Neoplasias do Sistema Nervoso Central/fisiopatologia , Endotelina-1/metabolismo , Glioblastoma/fisiopatologia , Metaloproteinase 13 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Astrócitos/fisiologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/fisiologia , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor de Endotelina A/metabolismo , Receptor de Endotelina B/metabolismo , Fator de Transcrição AP-1/metabolismoRESUMO
Regulatory T cells (Tregs) are important players in the tumor microenvironment. However, the mechanisms behind their immunosuppressive effects are poorly understood. We found that CCR6-CCL20 activity in tumor-infiltrating Tregs is associated with greater glycolytic activity and ablation of Ccr6 reduced glycolysis and lactic acid production while increasing compensatory glutamine metabolism. Immunosuppressive activity towards CD8+ T cells was abrogated in Ccr6-/- Tregs due to reduction in activation-induced glycolysis. Furthermore, Ccr6-/- mice exhibited improved survival across multiple tumor models compared to wildtype mice, and Treg and CD8+ T-cell depletion abrogated the improvement. In addition, Ccr6 ablation further promoted the efficacy of anti-PD-1 therapy in a preclinical glioma model. Follow-up knockdown of Ccl20 with siRNA also demonstrated improvement in antitumor efficacy. Our results unveil CCR6 as a marker and regulator of Treg-induced immunosuppression and identify approaches to target the metabolic determinants of Treg immunosuppressive activity.
RESUMO
Stimulator of IFN genes type I (STING-Type I) IFN signaling in myeloid cells plays a critical role in effective antitumor immune responses, but STING agonists as monotherapy have shown limited efficacy in clinical trials. The mechanisms that downregulate STING signaling are not fully understood. Here, we report that protein phosphatase 2A (PP2A), with its specific B regulatory subunit Striatin 4 (STRN4), negatively regulated STING-Type I IFN in macrophages. Mice with macrophage PP2A deficiency exhibited reduced tumor progression. The tumor microenvironment showed decreased immunosuppressive and increased IFN-activated macrophages and CD8+ T cells. Mechanistically, we demonstrated that Hippo kinase MST1/2 was required for STING activation. STING agonists induced dissociation of PP2A from MST1/2 in normal macrophages, but not in tumor conditioned macrophages. Furthermore, our data showed that STRN4 mediated PP2A binding to and dephosphorylation of Hippo kinase MST1/2, resulting in stabilization of YAP/TAZ to antagonize STING activation. In human patients with glioblastoma (GBM), YAP/TAZ was highly expressed in tumor-associated macrophages but not in nontumor macrophages. We also demonstrated that PP2A/STRN4 deficiency in macrophages reduced YAP/TAZ expression and sensitized tumor-conditioned macrophages to STING stimulation. In summary, we demonstrated that PP2A/STRN4-YAP/TAZ has, in our opinion, been an unappreciated mechanism that mediates immunosuppression in tumor-associated macrophages, and targeting the PP2A/STRN4-YAP/TAZ axis can sensitize tumors to immunotherapy.
Assuntos
Glioblastoma , Macrófagos Associados a Tumor , Animais , Humanos , Camundongos , Proteínas de Ligação a Calmodulina , Macrófagos , Processamento de Proteína Pós-Traducional , Transdução de Sinais , Microambiente Tumoral , Interferon Tipo I/metabolismoRESUMO
Gliomas are intrinsic brain tumors that originate from glial cells. Glioblastoma (GBM) is the most aggressive glioma type and resistant to immunotherapy, mainly due to its unique immune environment. Dimensional data analysis reveals that the intra-tumoral heterogeneity of immune cell populations in the glioma microenvironment is largely made up of cells of myeloid lineage. Conventional therapies of combined surgery, chemotherapy and radiotherapy have achieved limited improvements in the prognosis of glioma patients, as myeloid cells are prominent mediators of immune and therapeutic responses-like immunotherapy resistance-in glioma. Myeloid cells are frequently seen in the tumor microenvironment (TME), and they are polarized to promote tumorigenesis and immunosuppression. Reprogramming myeloid cells has emerged as revolutionary, new types of immunotherapies for glioma treatment. Here we detail the current advances in classifying epigenetic, metabolic, and phenotypic characteristics and functions of different populations of myeloid cells in glioma TME, including myeloid-derived suppressor cells (MDSCs), glioma-associated microglia/macrophages (GAMs), glioma-associated neutrophils (GANs), and glioma-associated dendritic cells (GADCs), as well as the mechanisms underlying promotion of tumorigenesis. The final goal of this review will be to provide new insights into novel therapeutic approaches for specific targeting of myeloid cells to improve the efficacy of current treatments in glioma patients.
Assuntos
Glioblastoma , Glioma , Carcinogênese , Glioblastoma/patologia , Glioblastoma/terapia , Humanos , Terapia de Imunossupressão , Células Mieloides , Microambiente TumoralRESUMO
Human glioma facilitates an impaired anti-tumor immunity response, including defects in circulation of T lymphocytes. The level of CD8+ T-cell activation acts as an immune regulator associated with disease progression. However, little is known about the characteristics of peripheral and tumor-infiltrating CD8+ T cells in patients with glioma. In this study, we examined the level of CD8+ T-cell activation in a group of 143 patients with glioma and determined that peripheral CD3+ T cells decreased in accordance with disease severity. The patients' peripheral CD8+ T-cell populations were similar to that of healthy donors, and a small amount of CD8+ tumor-infiltrating lymphocytes was identified in glioma tissues. An increase in activated CD8+ T cells, characterized as CD38+HLA-DR+, and their association with disease progression were identified in the patients' peripheral blood and glioma, and shown to display enriched CCR5+ and TNFR2+ expression levels. Ex vivo examination of CD38+HLA-DR+CD8+ T cells indicated that this subset of cells displayed stronger secretion of IFN-γ and IL-2 before and after a 6-h stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin (ION) relative to healthy CD38+HLA-DR+CD8+ T cells, indicating the functional feasibility of CD38+HLA-DR+CD8+ T cells. Higher CCL5 protein and mRNA levels were identified in glioma tissues, which was consistent with the immunohistochemistry results revealing both CCL5 and CD38+HLA-DR+CD8+ T cell expression. Patients' CCR5+CD38+HLA-DR+CD8+ T cells were further validated and shown to display increases in CD45RA+CCR7- and T-bet+ accompanied by substantial CD107-a, IFN-γ, and Granzyme B levels in response to glioma cells.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Glioma/imunologia , Microambiente Tumoral/imunologia , ADP-Ribosil Ciclase 1/imunologia , Adulto , Linfócitos T CD8-Positivos/patologia , Feminino , Glioma/patologia , Antígenos HLA-DR/imunologia , Humanos , Masculino , Glicoproteínas de Membrana/imunologia , Pessoa de Meia-Idade , Receptores CCR5/imunologiaRESUMO
Accumulating evidence suggests that neuroinflammation is closely associated with the pathogenesis of neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. The hallmark of neuroinflammation is considered to be microglial activation in the central nervous system (CNS). Activated microglia release pro-inflammatory cytokines which cause neuroinflammation and progressive neuronal cell death. Therefore, inhibition of microglial activation is considered an important strategy in the development of neuroprotective strategy. Naringenin, a flavonoid found in citrus fruits and tomatoes, has been reported to have anti-oxidant, anti-cancer, and anti-inflammatory properties. However, the mechanism of its beneficial anti-inflammatory effects in the CNS is poorly understood. In this study, we demonstrated that naringenin inhibites the release of nitric oxide (NO), the expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), as well as pro-inflammatory cytokines in microglial cells. Treatment of naringenin also induced suppressors of cytokine signaling (SOCS)-3 expression in microglia. The SOCS-3 expression and anti-inflammatory effects of naringenin were found to be regulated by adenosine monophosphate-activated protein kinase α (AMPKα) and protein kinase C δ (PKCδ). Besides, naringenin exerted protective property against neurotoxicity caused by LPS-induced microglial activation. Our findings suggest that naringenin-inhibited iNOS and COX-2 expression is mediated by SOCS-3 activation through AMPKα and PKCδ signaling pathways. In a mouse model, naringenin also showed significant protective effects on microglial activation and improved motor coordination function as well. Therefore, naringenin that involves in anti-neuroinflammatory responses and neuroprotection might be a potential agent for treatment of inflammation-associated disorders.
Assuntos
Flavanonas/farmacologia , Inflamação/metabolismo , Inflamação/patologia , Proteína 3 Supressora da Sinalização de Citocinas/metabolismo , Adenilato Quinase/metabolismo , Animais , Morte Celular/efeitos dos fármacos , Linhagem Celular , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Meios de Cultivo Condicionados/farmacologia , Ciclo-Oxigenase 2/metabolismo , Modelos Animais de Doenças , Ativação Enzimática/efeitos dos fármacos , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos , Masculino , Camundongos , Microglia/efeitos dos fármacos , Microglia/metabolismo , Atividade Motora/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/farmacologia , Óxido Nítrico Sintase Tipo II/metabolismo , Proteína Quinase C-delta/metabolismo , Transporte Proteico/efeitos dos fármacosRESUMO
BACKGROUND/OBJECTIVE: Nicardipine is a calcium channel blocker that has been widely used to control blood pressure in severe hypertension following events such as ischemic stroke, traumatic brain injury, and intracerebral hemorrhage. However, accumulating evidence suggests that inflammatory processes in the central nervous system that are mediated by microglial activation play important roles in neurodegeneration, and the effect of nicardipine on microglial activation remains unresolved. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, using murine BV-2 microglia, we demonstrated that nicardipine significantly inhibits microglia-related neuroinflammatory responses. Treatment with nicardipine inhibited microglial cell migration. Nicardipine also significantly inhibited LPS plus IFN-γ-induced release of nitric oxide (NO), and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Furthermore, nicardipine also inhibited microglial activation by peptidoglycan, the major component of the Gram-positive bacterium cell wall. Notably, nicardipine also showed significant anti-neuroinflammatory effects on microglial activation in mice in vivo. CONCLUSION/SIGNIFICANCE: The present study is the first to report a novel inhibitory role of nicardipine on neuroinflammation and provides a new candidate agent for the development of therapies for inflammation-related neurodegenerative diseases.