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Priming a vascular-selective cytokine response permits CD8+ T-cell entry into tumors

ABSTRACT: Targeting DNA methyltransferase 1 (DNMT1) has immunomodulatory and anti-neoplastic activity, especially when paired with cancer immunotherapies. Here we explored the immunoregulatory functions of DNMT1 in the tumor vasculature. Dnmt1 deletion in endothelial cells (ECs) impairs tumor growth and metastatic seeding while priming expression of cytokine-driven cell adhesion molecules and chemokines important for CD8+ T-cell trafficking across the vasculature; consequently, the efficacy of immune checkpoint blockade (ICB) is enhanced. Tumor ECs reduced in IFNg response genes are enriched in cell cycle effectors, including Dnmt1, indicating mitotic ECs suppress anti-tumor immune responses. Targeting Dnmt1 in ECs reduces proliferation and augments adhesion and diapedesis of CD8+ T-cells, suggesting Dnmt1 programs immunologically anergic tumor vasculature. Our study is in good accord with preclinical observations that pharmacologically disrupting DNMT1 enhances the activity of ICB, but suggests an epigenetic pathway presumed to be targeted in cancer cells, is also operative in the tumor vasculature.

ORGANISM(S): Mus musculus

PROVIDER: GSE186467 | GEO | 2022/05/02

REPOSITORIES: GEO

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Project description:The blood-brain barrier (BBB) dynamically controls and maintains a precisely balanced brain microenvironment necessary for reliable functioning. It is made up of highly specialized endothelial cells (ECs) in the lining of the vascular wall. These ECs are surrounded by the basal lamina, astrocytic perivascular endfeet, pericytes, microglia and neuronal processes that have been shown to contribute to barrier function1. In essence, the brain endothelium limits both transcellular and paracellular passage of cells and molecules into the central nervous system (CNS). Transcellular passage of hydrophilic molecules is limited due to a low rate of transcytotic vesicles, an extremely low pinocytotic activity, expression of active efflux transporters, and high metabolic activity. Paracellular diffusion of hydrophilic molecules and trafficking of immune cells is restricted by a network of tight junctions (TJs)2-5. Due to these characteristics, the BBB is able to protect the CNS from sudden changes in blood composition and uncontrolled influx of immune cells. In a large number of neuro-inflammatory diseases, an impaired function and an opening of the BBB are observed. In diseases of the CNS like multiple sclerosis or stroke or after brain trauma, the BBB becomes inflamed (mediated by for example reactive oxygen species (ROS) and hypoxia) and its function severely impaired which gives rise to enhanced cellular infiltration, thus contributing to tissue damage and neurological deficits. Due to the specialized nature of brain ECs, transmigration of leukocytes through cerebrovascular endothelium is likely to differ from that in other vascular beds. Generally, the transmigration process is closely controlled by the interaction of leukocytes with the endothelial surface followed by low velocity rolling, arrest, firm adhesion, and finally transmigration. For the diapedesis of immune cells across the cerebral vasculature a re-arrangement of the cytoskeleton and opening of the TJ complexes is required to allow cells to pass into the sub endothelial space. In the initial step of the adhesive cascade leukocytes adhere to the endothelium with low affinity. This adhesion is mediated by several members of the selectin family and their corresponding ligands. Despite the low affinity of these interactions, resulting contact of leukocytes with the endothelium leads to further activation of both cell types and finally transmigration of the leukocytes through the BBB6,7. The glycosylation of endothelial cells of different vascular bed origins To date it is unknown which specific carbohydrate structures on the BBB endothelium mediate leukocyte capture and rolling, and whether these structures are differentially expressed onto inflamed brain EC compared to normal brain ECs and vascular beds of other organs. Initial studies using qPCR and FACS analysis within our group reveal that brain endothelial cells have a different profile in their glycosylation-related genes compared to microvascular ECs upon inflammation, which may result in a different glycosylation profile of adhesive structures and may underlie rolling, adhesion and diapedesis of leukocytes. In this project we wish to identify specific, glycosylated structures on brain endothelial cells that mediate capture, rolling and diapedesis of leukocytes in the brain. To investigate the expression of glycosyltransferases in dendritic cells and the changes in expression associated with maturation. RNA preparations from stimulated and non-stimulated hcMEC/D3 (human brain endothelial cells line) and FMVEC (human promary microvascular endothelial cells isolated from foreskins) were sent to both Microarray Core (E) and Core(C). The RNA was put on an RNeasy Column, amplified, labeled, and hybridized to the Glycov3 microarrays. Data was sent to Dr. van Kooyk's lab for analysis.

Project description:Introduction Immune checkpoint blockade (ICB) is a systemic therapeutic option for advanced hepatocellular carcinoma (HCC). However, low patient response rates necessitate the development of robust predictive biomarkers that identify individuals who will benefit from ICB. A 4-gene inflammatory signature, comprising CD8, PD-L1, LAG-3, and STAT1, was recently shown to be associated with a better overall response to ICB in various cancer types. Here, we examined whether tissue protein expression of CD8, PD-L1, LAG-3, and STAT1 predicts response to ICB in HCC. Methods HCC samples from 191 Asian patients, comprising resection specimens from 124 patients (ICB-naïve) and pre-treatment specimens from 67 advanced HCC patients treated with ICB (ICB-treated), were analyzed for CD8, PD-L1, LAG-3, and STAT1 tissue expression using multiplex immunohistochemistry followed by statistical and survival analyses. Results Immunohistochemical and survival analyses of ICB-naïve samples showed that high LAG-3 expression was associated with shorter median progression-free survival (mPFS) and overall survival (mOS). Analysis of ICB-treated samples revealed that high proportions of LAG-3+ and LAG-3+CD8+ cells pre-treatment were most closely associated with longer mPFS and mOS. Using a log-likelihood model, adding the total LAG-3+ cell proportion to the total CD8+ cell proportion significantly increased the predictive values for mPFS and mOS, compared with the total CD8+ cell proportion alone. Moreover, levels of CD8 and STAT1, but not PD-L1, were significantly correlated with better responses to ICB. After analyzing viral-related and non-viral HCC samples separately, only the LAG3+CD8+ cell proportion was significantly associated with responses to ICB regardless of viral status. Conclusion Immunohistochemical scoring of pre-treatment levels of LAG-3 and CD8 in the tumor microenvironment may help predict ICB benefits in HCC patients. Furthermore, immunohistochemistry-based techniques offer the advantage of being readily translatable in the clinical setting.

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Priming a vascular-selective cytokine response permits CD8+ T-cell entry into tumors

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