PD-1/PD-L1 checkpoint blockade harnesses monocyte-derived macrophages to combat cognitive impairment in a tauopathy mouse model
Ontology highlight
ABSTRACT: Alzheimer’s disease (AD) is a heterogeneous disorder with multiple etiologies. Harnessing the immune system by blocking the programmed cell death receptor (PD)-1 pathway in an amyloid beta mouse model was shown to evoke a sequence of immune responses that lead to disease modification. Here, blocking PD-L1, a PD-1 ligand, was found to have similar efficacy to that of PD-1 blocking in disease modification, in both animal models of AD and of tauopathy. Targeting PD-L1 in a tau-driven disease model resulted in increased immunomodulatory monocyte-derived macrophages within the brain parenchyma. Single cell RNA-seq revealed that the homing macrophages expressed unique scavenger molecules including macrophage scavenger receptor 1 (MSR1), which was shown here to be required for the effect of PD-L1 blockade in disease modification. Overall, our results demonstrate that immune checkpoint blockade targeting the PD-1/PD-L1 pathway leads to modification of common factors that go awry in AD and dementia, and thus can potentially provide an immunotherapy to help combat these diseases.
Project description:Microglia and monocyte-derived macrophages (MDM) are key players in coping with Alzheimer's disease (AD). In amyloidosis mouse models, activation of microglia was found to be TREM2-dependent. Here, using Trem2-/-5xFAD mice, we assessed whether MDM act via a TREM2-dependent pathway. We adopted a treatment protocol targeting the programmed cell death ligand-1 (PD-L1) immune checkpoint, previously shown to modify AD via MDM involvement. Blocking PD-L1 in Trem2-/-5xFAD mice resulted in cognitive improvement and reduced levels of water-soluble amyloid beta (Aβ)1-42 with no effect on amyloid plaque burden. Single-cell RNA sequencing revealed that MDM, derived from both Trem2-/- and Trem2+/+5xFAD mouse brains, express a unique set of genes encoding scavenger receptors (e.g. Mrc1, Msr1). Blocking monocytes trafficking using anti-CCR2 antibody completely abrogated the cognitive improvement induced by anti-PD-L1 in Trem2-/-5xFAD mice, and similarly but to lower extent in Trem2+/+5xFAD mice. These results highlight a TREM2-independent disease-modifying activity of MDM in amyloidosis mouse model.
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.
Project description:Blocking PD-1 can reinvigorate exhausted CD8 T cells (TEX) and improve control of chronic infections and cancer. One potential advantage of this immunotherapy is durable protection if immune memory can be established. It is unclear, however, whether blocking PD-1 can reprogram TEX into effector (TEFF) or durable memory T cells (TMEM). Here, we found reinvigoration of TEX by PD-L1 blockade caused re-acquisition of some features of TEFF, but minimal memory development. We used microarray analysis to profile exhausted cells from anti-PD-L1 mice after two weeks of treatment to study if PD-L1 blockade caused re-acquistion of some feature of effector or memory cells.
Project description:<p>Desmoplastic melanoma (DM) is a rare subtype of melanoma characterized by dense fibrous stroma, resistance to chemotherapy and a lack of actionable driver mutations, but is highly associated with ultraviolet light DNA damage. We analysed 60 patients with advanced DM treated with programmed cell death 1 (PD-1) or PD-1 ligand (PD-L1) blocking antibody therapy. Objective tumor responses were observed in 42 of the 60 patients (70%, 95% confidence interval 57-81%), including 19 patients (32% overall) with a complete response. Whole-exome sequencing revealed a high mutational load and frequent NF-1 mutations (14 out of 17 cases). Immunohistochemistry (IHC) analysis from 19 DM and 13 non-DM revealed a higher percentage of PD-L1 positive cells in the tumor parenchyma in DM (p = 0.04), highly associated with increased CD8 density and PD-L1 expression in the tumor invasive margin. Therefore, patients with advanced DM derive significant clinical benefit from PD-1/PD-L1 immune checkpoint blockade therapy despite being a cancer defined by its dense desmoplastic fibrous stroma. The benefit is likely derived from the high mutational burden and a frequent pre-existing adaptive immune response limited by PD-L1 expression.</p>
Project description:Immunol checkpoint blockade therapy targeting programmed-death 1 (PD-1) and its ligand PD-L1 can effectively prevent tumor immune escaping, and has been recognized with remarkable clinical benefits on cancer. Currently, antibody drugs take effect by blocking the target on the cell membrane. However, antibody drugs still face challenges in the aspect of deep penetration, multivalent recognition and chemical synthesis. Rationally designed targeting peptides is the befitting units for construction of the ‘nano antibody’. We first report herein a new peptide-AIE (aggregation-induced emission) hybrid supramolecular TPDP, which can specifically bind PD-L1 in vivo and in vitro with nanomolar affinity. It can be triggered by PD-L1 into ordered-aggregation ‘nano-spiderwebs’ and compactly cocoon the lesion surface and block PD-1/PD-L1 interaction on both membrane and cytoplasm in a dynamic manner, showing competitive effect over antibodies. It showed excellent in vivo tumor therapy effect in patient derived xenograft mice (PDX). What’s more, PD-L1 targeted antibody drugs take effect by blocking PD-L1 on the cell membrane, but intracellular PD-L1 are hard to be affect and like to be relocated on the membrane, which decreases the therapeutic benefits. In this study, the nano-spiderwebs could penetrate deeply into the cytoplasm and down-regulate the endogenous PD-L1 expression of the host, which could reduce the feedback of intracellular storage of PD-L1. We envision that this receptor-induced peptide ‘nano-spiderwebs’ will open an avenue for both blockade and inhibitor against PD-L1 and provide alternatives for targeting diagnostics and therapeutics towards this immune checkpoint.
Project description:A hallmark of PD-1/L1 blockade is long-term, sustained remission of metastatic disease. How the immune system coordinates the destruction of macro- and micro-metastases following checkpoint blockade, however, remains unclear. Here, we show that tumor-expressed PD-L1 (tPD-L1) enhanced metastasis in a mechanism distinct from and independent of its role in primary tumor growth. This difference in metastatic growth was mediated by cytotoxic T lymphocytes (CTLs), however, tPD-L1 did not promote effector CTL exhaustion or suppress lytic activity in vivo. Instead, single cell RNA sequencing revealed that tPD-L1 engaged macrophage-expressed PD-1 to antagonize type I interferon production and signaling, creating an immunologically ‘cold’ microenvironment. Loss of tPD-L1 eliminated metastases by driving interferon-mediated sensitization of tumor cells to CTL lysis and CTL recruitment.
Project description:A hallmark of PD-1/L1 blockade is long-term, sustained remission of metastatic disease. How the immune system coordinates the destruction of macro- and micro-metastases following checkpoint blockade, however, remains unclear. Here, we show that tumor-expressed PD-L1 (tPD-L1) enhanced metastasis in a mechanism distinct from and independent of its role in primary tumor growth. This difference in metastatic growth was mediated by cytotoxic T lymphocytes (CTLs), however, tPD-L1 did not promote effector CTL exhaustion or suppress lytic activity in vivo. Instead, single cell RNA sequencing revealed that tPD-L1 engaged macrophage-expressed PD-1 to antagonize type I interferon production and signaling, creating an immunologically ‘cold’ microenvironment. Loss of tPD-L1 eliminated metastases by driving interferon-mediated sensitization of tumor cells to CTL lysis and CTL recruitment.
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.
Project description:Rationale: T cell activation is a key antimicrobial component against mycobacterial disease. Programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) pathway could affect the antimicrobial immune responses by suppressing T cell activity. Several recent studies demonstrated that blocking of PD-1/PD-L1 pathway exacerbated Mycobacterium tuberculosis infection. However, the influence of blocking this pathway in pulmonary Mycobacterium avium-intracellulare complex (MAC) infection was not fully understood. Objective: We aimed to determine the influence of genetic depletion of PD-1/PD-L1 pathway on the disease activity of MAC infection. Methods: Wild-type, PD-1-deficient mice and PD-L1-deficient mice were intranasally infected with Mycobacterium avium bacteria. Measurements and Main Results: The depletion of PD-1 or PD-L1 did not affect mortality and bacterial burden in mice infected with MAC. However, remarkable infiltration of CD8 T lymphocytes was observed in the lungs of PD-1 and PD-L1 deficient mice compared to wild-type mice. Comprehensive transcriptome analysis showed that levels of gene expressions related to Th1 immunity did not differ according to the genotypes. However, genes related to the activity of CD8 T cells and related chemokine activity were up-regulated in the infected lungs of PD-1 and PD-L1 deficient mice. Conclusions: Depletion of PD-1/PD-L1 pathway did not affect the activation of Th1 immunity in response to MAC infection, which may explain why MAC infection was controlled in these mice. In addition, CD8-positive T cell pulmonary inflammation in knockout mice might have some clinical implication in the treatment of cancer patients with immune checkpoint inhibitors when the patients are infected with MAC.
Project description:Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), and Parkinson’s disease dementia (PDD) collectively represent the majority of dementia cases worldwide. While these subtypes share clinical, genetic, and pathological features, their transcriptomic similarities and differences remain poorly understood. We applied single-nucleus RNA-sequencing (snRNA-seq) to prefrontal cortex samples from individuals with non-cognitive impairment control (NCI), and dementia subtypes (AD, DLB, and PDD) to investigate cell type-specific gene expression patterns and pathways underlying pathological similarities and differences across dementia subtypes. SnRNA-seq findings were validated through RNAscope, immunohistochemistry, and additional biochemical analyses in human tissues and cellular models. snRNA-seq analysis revealed elevated microglial proportions across all dementia subtypes compared to NCI. Further analysis of cell type-specific transcriptomes identified overlapping differentially expressed genes (DEGs) between microglia and oligodendrocytes across all dementia subtypes. While AD showed molecular similarities to NCI, PDD and DLB were clustered more closely together, sharing a greater number of DEGs and related pathways, predominantly associated with microglia. Investigation of interactions between microglia and oligodendrocytes revealed a distinct myelin-enriched microglia (MEM) subcluster in all dementia subtypes. MSR1, a gene encoding a scavenger receptor, was upregulated in microglia across all dementia subtypes, along with its associated gene HSPA1A in oligodendrocytes. RNAscope supported the potential interaction between microglia and oligodendrocytes, where these cells were in closer proximity to each other in human cortical tissues of PDD compared to NCI. MSR1 expression was significantly increased in cortical primary microglia from PD mice compared with non-transgenic (NTg) mice. Additionally, the expression of myelin-associated genes (MBP, MOBP and PLP1) was significantly upregulated in PD microglia compared to NTg, supporting the presence of MEM. Furthermore, MSR1-positive microglia colocalised with MBP in cortical tissue of PDD patients, suggesting a functional role of MSR1 in myelin debris clearance. Overexpression of MSR1 in microglial cells enhanced their phagocytic activity toward myelin, and reciprocally, myelin treatment upregulated MSR1 protein levels, indicating enhanced MSR1-mediated myelin phagocytosis.