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Project description:Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disorder of the central nervous system (CNS). Current therapies mainly target inflammatory processes during acute stages, but effective treatments for progressive MS are limited. In this context, astrocytes have gained increasing attention as they have the capacity to drive, but also suppress tissue-degeneration. Here we show that astrocytes upregulate the immunomodulatory checkpoint molecule PD-L1 during acute autoimmune CNS inflammation in response to aryl hydrocarbon receptor and interferon signaling. Using CRISPR-Cas9 genetic perturbation in combination with small-molecule and antibody-mediated inhibition of PD-L1 and PD-1 both in vivo and in vitro, we demonstrate that astrocytic PD-L1 and its interaction with microglial PD-1 is required for the attenuation of autoimmune CNS inflammation in acute and progressive stages in a mouse model of MS. Our findings suggest the glial PD-L1 / PD-1 axis as a new therapeutic target for both acute and progressive MS stages.
2023-08-02 | GSE239874 | GEO
Project description:Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disorder of the central nervous system (CNS). Current therapies mainly target inflammatory processes during acute stages, but effective treatments for progressive MS are limited. In this context, astrocytes have gained increasing attention as they have the capacity to drive, but also suppress tissue-degeneration. Here we show that astrocytes upregulate the immunomodulatory checkpoint molecule PD-L1 during acute autoimmune CNS inflammation in response to aryl hydrocarbon receptor and interferon signaling. Using CRISPR-Cas9 genetic perturbation in combination with small-molecule and antibody-mediated inhibition of PD-L1 and PD-1 both in vivo and in vitro, we demonstrate that astrocytic PD-L1 and its interaction with microglial PD-1 is required for the attenuation of autoimmune CNS inflammation in acute and progressive stages in a mouse model of MS. Our findings suggest the glial PD-L1 / PD-1 axis as a new therapeutic target for both acute and progressive MS stages.
2023-08-02 | GSE239873 | GEO
Project description:IntroductionThe experimental cerebral malaria (ECM) model in C57BL/6 mice infected with Plasmodium berghei ANKA (PbA) has revealed microglia are involved in the ECM immune microenvironment. However, the regulation of microglia in the ECM immune response is not clear, and there is no safe and efficient treatment clinically for the protection of the nerve cells.AimsTo elucidate the negative regulation mechanism in the ECM brain mediated by microglia. Furthermore, to investigate protective effect of the appropriate enhancement of the PD-1/PD-L1 pathway in the brain against ECM through the intrathecal injection of the adenovirus expressing PDL1-IgG1Fc fusion protein.ResultsThe PD-1/PD-L1 pathway was induced in the ECM brain and showed an upregulation in the microglia. Deep single-cell analysis of immune niches in the ECM brainstem indicated that the microglia showed obvious heterogeneity and activation characteristics. Intrathecal injection of recombinant adenovirus expressing PD-L1 repressed the neuroinflammation and alleviated ECM symptoms. In addition, the synergistic effect of artemisinin and intracranial immunosuppression mediated by PD-L1 was more efficacious than either treatment alone.ConclusionThe appropriate enhancement of the PD-1/PD-L1 pathway in the early stage of ECM has an obvious protective effect on the maintenance of immune microenvironment homeostasis in the brain. Regulating microglia and the PD-1/PD-L1 pathway could be considered as a promising approach for protection against human cerebral malaria in the future.
| S-EPMC8673706 | biostudies-literature
Project description:Neuroinflammation, a pathogenic component of Alzheimer disease (AD), may limit the ability of the brain to clear deposits and debris. Tight control of the immune system may therefore be key to sustain the ability of the brain for repair and clearance. Here we report that PD-L1 on astrocytes and its receptor PD-1 on microglia, known for its inhibitory immune function, are upregulated around amyloid plaques in AD and APP/PS1 mice. Juxtamembrane shedding of PD-L1 was observed from astrocytes suggesting ectodomain signaling to microglial PD-1. Deletion of PD-1 in microglia evoked an inflammatory response and compromised Aβ uptake. Likewise, in APP/PS1 PD-1-/- mice increased deposition of amyloid β (Aβ), reduced microglial Aβ uptake, and decreased expression of the Aβ receptor CD36 on microglia were detected. Therefore, ineffective immune regulation by the PD-1/PD-L1 axis contributes to Aβ plaque deposition during chronic, unresolved neuroinflammation in AD.
| S-SCDT-EMBOJ-2021-108662 | biostudies-other
Project description:Blocking the PD-1/PD-L1 immunosuppressive pathway has shown promise in the treatment of certain cancers including melanoma. This study investigates differences in the gene expression profiles of human melanomas that do or do not display the immunosuppressive protein PD-L1. Further understanding of genes expressed within the tumor microenvironment of PD-L1+ tumors may lead to improved rationally designed treatments. Gene expression profiling was performed on total RNA extracted by laser capture microdissection from 11 archived formalin-fixed paraffin-embedded (FFPE) melanoma specimens, 5 of which were PD-L1 positive and 6 PD-L1 negative. Details of the design, and the gene signatures found are given in the paper associated with this GEO Series: Janis M. Taube, Geoffrey D. Young, Tracee L. McMiller, Shuming Chen, January T. Salas, Theresa S. Pritchard, Haiying Xu, Alan K. Meeker, Jinshui Fan, Chris Cheadle, Alan E. Berger, Drew M. Pardoll, and Suzanne L. Topalian, Differential expression of immune-regulatory genes associated with PD-L1 display in melanoma: implications for PD-1 pathway blockade, Clin Cancer Res 2015, in press.
2015-05-01 | E-GEOD-65041 | biostudies-arrayexpress
Project description:Ganoderma lucidum (GL) has been widely used in Asian countries for hundreds of years to promote health and longevity. The pharmacological functions of which had been classified, including the activation of innate immune responses, suppression of tumour and modulation of cell proliferations. Effective fractions of Ganoderma lucidum polysaccharides (GLP) had already been reported to regulate the immune system. Nevertheless, the role of GLP in the microglia-mediated neuroinflammation has not been sufficiently elucidated. Further, GLP effect on microglial behavioural modulations in correlation with the inflammatory responses remains to be unravelled. The aim of this work was to quantitatively analyse the contributions of GLP on microglia.The BV2 microglia and primary mouse microglia were stimulated by lipopolysaccharides (LPS) and amyloid beta42 (A?42) oligomer, respectively. Investigation on the effect of GLP was carried by quantitative determination of the microglial pro- and anti-inflammatory cytokine expressions and behavioural modulations including migration, morphology and phagocytosis. Analysis of microglial morphology and phagocytosis modulations was confirmed in the zebrafish brain.Quantitative results revealed that GLP down-regulates LPS- or A?-induced pro-inflammatory cytokines and promotes anti-inflammatory cytokine expressions in BV-2 and primary microglia. In addition, GLP attenuates inflammation-related microglial migration, morphological alterations and phagocytosis probabilities. We also showed that modulations of microglial behavioural responses were associated with MCP-1 and C1q expressions.Overall, our study provides an insight into the GLP regulation of LPS- and A?-induced neuroinflammation and serves an implication that the neuroprotective function of GLP might be achieved through modulation of microglial inflammatory and behavioural responses.
| S-EPMC5364682 | biostudies-other
Project description:Chronic neuroinflammation is a pathogenic component of Alzheimer's disease (AD) that may limit the ability of the brain to clear amyloid deposits and cellular debris. Tight control of the immune system is therefore key to sustain the ability of the brain to repair itself during homeostasis and disease. The immune-cell checkpoint receptor/ligand pair PD-1/PD-L1, known for their inhibitory immune function, is expressed also in the brain. Here, we report upregulated expression of PD-L1 and PD-1 in astrocytes and microglia, respectively, surrounding amyloid plaques in AD patients and in the APP/PS1 AD mouse model. We observed juxtamembrane shedding of PD-L1 from astrocytes, which may mediate ectodomain signaling to PD-1-expressing microglia. Deletion of microglial PD-1 evoked an inflammatory response and compromised amyloid-β peptide (Aβ) uptake. APP/PS1 mice deficient for PD-1 exhibited increased deposition of Aβ, reduced microglial Aβ uptake, and decreased expression of the Aβ receptor CD36 on microglia. Therefore, ineffective immune regulation by the PD-1/PD-L1 axis contributes to Aβ plaque deposition during chronic neuroinflammation in AD.
| S-EPMC8672180 | biostudies-literature
Project description:Astroglial reactivity associated with increased production of NFkappaB-dependent proinflammatory molecules is an important component of the pathophysiology of chronic neurological disorders such as multiple sclerosis (MS). The use of estrogens as potential anti-inflammatory and neuroprotective drugs is a matter of debate. Using mouse experimental allergic encephalomyelitis (EAE) as a model of chronic neuroinflammation, we report that implants reproducing pregnancy levels of 17beta-estradiol (E2) alleviate ongoing disease and decrease astrocytic production of CCL2, a proinflammatory chemokine that drives the local recruitment of inflammatory myeloid cells. Immunohistochemistry and confocal imaging reveal that, in spinal cord white matter EAE lesions, reactive astrocytes express estrogen receptor (ER)alpha (and to a lesser extent ERbeta) with a preferential nuclear localization, whereas other cells including infiltrated leukocytes express ERs only in their membranes or cytosol. In cultured rodent astrocytes, E2 or an ERalpha agonist, but not an ERbeta agonist, inhibits TNFalpha-induced CCL2 expression at nanomolar concentrations, and the ER antagonist ICI 182,170 blocks this effect. We show that this anti-inflammatory action is not associated with inhibition of NFkappaB nuclear translocation but rather involves direct repression of NFkappaB-dependent transcription. Chromatin immunoprecipitation assays further indicate that estrogen suppresses TNFalpha-induced NFkappaB recruitment to the CCL2 enhancer. These data uncover reactive astrocytes as an important target for nuclear ERalpha inhibitory action on chemokine expression and suggest that targeting astrocytic nuclear NFkappaB activation with estrogen receptor alpha modulators may improve therapies of chronic neurodegenerative disorders involving astroglial neuroinflammation.
| S-EPMC2889572 | biostudies-literature
Project description:Matrix metalloproteinases (MMPs) play a pivotal role in neuroinflammation that is associated with neurodegenerative diseases. Our group recently reported that MMP-8 mediates inflammatory reactions by modulating the processing of TNF-α. To improve the efficacy of the currently available MMP-8 inhibitor (M8I), we have synthesized structurally modified M8I derivatives (comp 2, 3, 4, 5) and compared their efficacy with original compound (comp 1). Among M8I derivatives, comp 2, 3, and 5 inhibited the production of NO, ROS, and IL-6 more efficiently than the original compound in lipopolysaccharide (LPS)-stimulated microglia. When we compared the anti-inflammatory mechanisms of the most effective derivative, comp 3, with comp 1, comp 3 suppressed the mRNA expression of iNOS and cytokines more efficiently than comp 1. Although comp 1 inhibits only TNF-α processing, comp 3 additionally inhibits the expression of TNF-α. Both compounds inhibited LPS-induced activity of MAP kinases, NF-κB, and AP-1, while they increased heme oxygenase-1 expression by upregulating AMPK-Nrf2 signaling. Overall, the effect of comp 3 on anti-inflammatory signaling was much stronger than comp 1. We verified the anti-inflammatory effects of comp 1 and 3 in the LPS-injected mouse brain and primary cultured astrocytes. Comp 1 and 3 suppressed microglial activation, astrogliosis, and proinflammatory gene expression in the brain. Moreover, the compounds inhibited proinflammatory gene expression in the cultured astrocytes. Collectively, our data suggest that the MMP-8 inhibitor may be a promising therapeutic agent for neuroinflammatory disorders.
| S-EPMC5667990 | biostudies-literature
Project description:The PD-1 pathway, consisting of the co-inhibitory receptor PD-1 on T cells and its ligand (PD-L1) on antigen-presenting cells (APCs), is a major mechanism of tumor immune evasion. PD-1 and PD-L1 blockade antibodies have produced remarkable clinical activities against a subset of cancers. Binding between T cell-intrinsic PD-1 and APC-intrinsic PD-L1 triggers inhibitory signaling to attenuate the T cell response. Here, we report that PD-1 is co-expressed with PD-L1 on tumor cells and tumor-infiltrating APCs. Using reconstitution and cell culture assays, we demonstrate that the co-expressed PD-1 binds to PD-L1 in cis. Such interaction inhibits the ability of PD-L1 to bind T cell-intrinsic PD-1 in trans and, in turn, represses canonical PD-L1/PD-1 inhibitory signaling. Selective blockade of tumor-intrinsic PD-1 frees up tumor-intrinsic PD-L1 to inhibit T cell signaling and cytotoxicity. Our study uncovers another dimension of PD-1 regulation, with important therapeutic implications.
| S-EPMC6093302 | biostudies-literature