PGE2 limits effector expansion of tumour-infiltrating stem-like CD8+ T cells.

Cancer-specific TCF1+ stem-like CD8+ T cells can drive protective anticancer immunity through expansion and effector cell differentiation1-4; however, this response is dysfunctional in tumours. Current cancer immunotherapies2,5-9 can promote anticancer responses through TCF1+ stem-like CD8+ T cells in some but not all patients. This variation points towards currently ill-defined mechanisms that limit TCF1+CD8+ T cell-mediated anticancer immunity. Here we demonstrate that tumour-derived prostaglandin E2 (PGE2) restricts the proliferative expansion and effector differentiation of TCF1+CD8+ T cells within tumours, which promotes cancer immune escape. PGE2 does not affect the priming of TCF1+CD8+ T cells in draining lymph nodes. PGE2 acts through EP2 and EP4 (EP2/EP4) receptor signalling in CD8+ T cells to limit the intratumoural generation of early and late effector T cell populations that originate from TCF1+ tumour-infiltrating CD8+ T lymphocytes (TILs). Ablation of EP2/EP4 signalling in cancer-specific CD8+ T cells rescues their expansion and effector differentiation within tumours and leads to tumour elimination in multiple mouse cancer models. Mechanistically, suppression of the interleukin-2 (IL-2) signalling pathway underlies the PGE2-mediated inhibition of TCF1+ TIL responses. Altogether, we uncover a key mechanism that restricts the IL-2 responsiveness of TCF1+ TILs and prevents anticancer T cell responses that originate from these cells. This study identifies the PGE2-EP2/EP4 axis as a molecular target to restore IL-2 responsiveness in anticancer TILs to achieve cancer immune control.

A distinct stimulatory cDC1 subpopulation amplifies CD8+ T cell responses in tumors for protective anti-cancer immunity.

Type 1 conventional dendritic cells (cDC1) can support T cell responses within tumors but whether this determines protective versus ineffective anti-cancer immunity is poorly understood. Here, we use imaging-based deep learning to identify intratumoral cDC1-CD8+ T cell clustering as a unique feature of protective anti-cancer immunity. These clusters form selectively in stromal tumor regions and constitute niches in which cDC1 activate TCF1+ stem-like CD8+ T cells. We identify a distinct population of immunostimulatory CCR7neg cDC1 that produce CXCL9 to promote cluster formation and cross-present tumor antigens within these niches, which is required for intratumoral CD8+ T cell differentiation and expansion and promotes cancer immune control. Similarly, in human cancers, CCR7neg cDC1 interact with CD8+ T cells in clusters and are associated with patient survival. Our findings reveal an intratumoral phase of the anti-cancer T cell response orchestrated by tumor-residing cDC1 that determines protective versus ineffective immunity and could be exploited for cancer therapy.

Tumor-derived prostaglandin E2 programs cDC1 dysfunction to impair intratumoral orchestration of anti-cancer T cell responses.

Type 1 conventional dendritic cells (cDC1s) are critical for anti-cancer immunity. Protective anti-cancer immunity is thought to require cDC1s to sustain T cell responses within tumors, but it is poorly understood how this function is regulated and whether its subversion contributes to immune evasion. Here, we show that tumor-derived prostaglandin E2 (PGE2) programmed a dysfunctional state in intratumoral cDC1s, disabling their ability to locally orchestrate anti-cancer CD8+ T cell responses. Mechanistically, cAMP signaling downstream of the PGE2-receptors EP2 and EP4 was responsible for the programming of cDC1 dysfunction, which depended on the loss of the transcription factor IRF8. Blockade of the PGE2-EP2/EP4-cDC1 axis prevented cDC1 dysfunction in tumors, locally reinvigorated anti-cancer CD8+ T cell responses, and achieved cancer immune control. In human cDC1s, PGE2-induced dysfunction is conserved and associated with poor cancer patient prognosis. Our findings reveal a cDC1-dependent intratumoral checkpoint for anti-cancer immunity that is targeted by PGE2 for immune evasion.

TIMP-1 is a novel ligand of Amyloid Precursor Protein and triggers a proinflammatory phenotype in human monocytes.

The emerging cytokine tissue inhibitor of metalloproteinases-1 (TIMP-1) correlates with the progression of inflammatory diseases, including cancer. However, the effects of TIMP-1 on immune cell activation and underlying molecular mechanisms are largely unknown. Unbiased ligand-receptor-capture-screening revealed TIMP-1-interaction with Amyloid Precursor Protein (APP) family members, namely APP and Amyloid Precursor-like Protein-2 (APLP2), which was confirmed by pull-down assays and confocal microscopy. We found that TIMP-1 triggered glucose uptake and proinflammatory cytokine expression in human monocytes. In cancer patients, TIMP-1 expression positively correlated with proinflammatory cytokine expression and processes associated with monocyte activation. In pancreatic cancer, TIMP-1 plasma levels correlated with the monocyte activation marker sCD163, and the combined use of both clinically accessible plasma proteins served as a powerful prognostic indicator. Mechanistically, TIMP-1 triggered monocyte activation by its C-terminal domain and via APP as demonstrated by in vitro interference, in silico docking, and the employment of recombinant TIMP-1 variants. Identification of TIMP-1 as a trigger of monocyte activation opens new therapeutic perspectives for inflammatory diseases.

Guidelines for visualization and analysis of DC in tissues using multiparameter fluorescence microscopy imaging methods.

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy, and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs and various non-lymphoid tissues. Here, we provide detailed procedures for a variety of multiparameter fluorescence microscopy imaging methods to explore the spatial organization of DC in tissues and to dissect how DC migrate, communicate, and mediate their multiple functional roles in immunity in a variety of tissue settings. The protocols presented here entail approaches to study DC dynamics and T cell cross-talk by intravital microscopy, large-scale visualization, identification, and quantitative analysis of DC subsets and their functions by multiparameter fluorescence microscopy of fixed tissue sections, and an approach to study DC interactions with tissue cells in a 3D cell culture model. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all co-authors, making it an essential resource for basic and clinical DC immunologists.

Identification of invariant chain CD74 as a functional receptor of tissue inhibitor of metalloproteinases-1 (TIMP-1).

Multifunctionality of tissue inhibitor of metalloproteinases-1 (TIMP-1) comprising antiproteolytic as well as cytokinic activity has been attributed to its N-terminal and C-terminal domains, respectively. The molecular basis of the emerging proinflammatory cytokinic activity of TIMP-1 is still not completely understood. The cytokine receptor invariant chain (CD74) is involved in many inflammation-associated diseases and is highly expressed by immune cells. CD74 triggers zeta chain-associated protein kinase-70 (ZAP-70) signaling-associated activation upon interaction with its only known ligand, the macrophage migration inhibitory factor. Here, we demonstrate TIMP-1-CD74 interaction by coimmunoprecipitation and confocal microscopy in cells engineered to overexpress CD74. In silico docking in HADDOCK predicted regions of the N-terminal domain of TIMP-1 (N-TIMP-1) to interact with CD74. This was experimentally confirmed by confocal microscopy demonstrating that recombinant N-TIMP-1 lacking the entire C-terminal domain was sufficient to bind CD74. Interaction of TIMP-1 with endogenously expressed CD74 was demonstrated in the Namalwa B lymphoma cell line by dot blot binding assays as well as confocal microscopy. Functionally, we demonstrated that TIMP-1-CD74 interaction triggered intracellular ZAP-70 activation. N-TIMP-1 was sufficient to induce ZAP-70 activation and interference with the cytokine-binding site of CD74 using a synthetic peptide-abrogated TIMP-1-mediated ZAP-70 activation. Altogether, we here identified CD74 as a receptor and mediator of cytokinic TIMP-1 activity and revealed TIMP-1 as moonlighting protein harboring both cytokinic and antiproteolytic activity within its N-terminal domain. Recognition of this functional TIMP-1-CD74 interaction may shed new light on clinical attempts to therapeutically target ligand-induced CD74 activity in cancer and other inflammatory diseases.

Auto-aggressive CXCR6+ CD8 T cells cause liver immune pathology in NASH.

Nonalcoholic steatohepatitis (NASH) is a manifestation of systemic metabolic disease related to obesity, and causes liver disease and cancer1,2. The accumulation of metabolites leads to cell stress and inflammation in the liver3, but mechanistic understandings of liver damage in NASH are incomplete. Here, using a preclinical mouse model that displays key features of human NASH (hereafter, NASH mice), we found an indispensable role for T cells in liver immunopathology. We detected the hepatic accumulation of CD8 T cells with phenotypes that combined tissue residency (CXCR6) with effector (granzyme) and exhaustion (PD1) characteristics. Liver CXCR6+ CD8 T cells were characterized by low activity of the FOXO1 transcription factor, and were abundant in NASH mice and in patients with NASH. Mechanistically, IL-15 induced FOXO1 downregulation and CXCR6 upregulation, which together rendered liver-resident CXCR6+ CD8 T cells susceptible to metabolic stimuli (including acetate and extracellular ATP) and collectively triggered auto-aggression. CXCR6+ CD8 T cells from the livers of NASH mice or of patients with NASH had similar transcriptional signatures, and showed auto-aggressive killing of cells in an MHC-class-I-independent fashion after signalling through P2X7 purinergic receptors. This killing by auto-aggressive CD8 T cells fundamentally differed from that by antigen-specific cells, which mechanistically distinguishes auto-aggressive and protective T cell immunity.

IL-1-conferred gene expression pattern in ERα+ BCa and AR+ PCa cells is intrinsic to ERα- BCa and AR- PCa cells and promotes cell survival.

BACKGROUND: Breast (BCa) and prostate (PCa) cancers are hormone receptor (HR)-driven cancers. Thus, BCa and PCa patients are given therapies that reduce hormone levels or directly block HR activity; but most patients eventually develop treatment resistance. We have previously reported that interleukin-1 (IL-1) inflammatory cytokine downregulates ERα and AR mRNA in HR-positive (HR+) BCa and PCa cell lines, yet the cells can remain viable. Additionally, we identified pro-survival proteins and processes upregulated by IL-1 in HR+ BCa and PCa cells, that are basally high in HR- BCa and PCa cells. Therefore, we hypothesize that IL-1 confers a conserved gene expression pattern in HR+ BCa and PCa cells that mimics conserved basal gene expression patterns in HR- BCa and PCa cells to promote HR-independent survival and tumorigenicity. METHODS: We performed RNA sequencing (RNA-seq) for HR+ BCa and PCa cell lines exposed to IL-1 and for untreated HR- BCa and PCa cell lines. We confirmed expression patterns of select genes by RT-qPCR and used siRNA and/or drug inhibition to silence select genes in the BCa and PCa cell lines. Finally, we performed Ingenuity Pathway Analysis (IPA) and used the gene ontology web-based tool, GOrilla, to identify signaling pathways encoded by our RNA-seq data set. RESULTS: We identified 350 genes in common between BCa and PCa cells that are induced or repressed by IL-1 in HR+ cells that are, respectively, basally high or low in HR- cells. Among these genes, we identified Sequestome-1 (SQSTM1/p62) and SRY (Sex-Determining Region Y)-Box 9 (SOX9) to be essential for survival of HR- BCa and PCa cell lines. Analysis of publicly available data indicates that p62 and SOX9 expression are elevated in HR-independent BCa and PCa sublines generated in vitro, suggesting that p62 and SOX9 have a role in acquired hormone receptor independence and treatment resistance. We also assessed HR- cell line viability in response to the p62-targeting drug, verteporfin, and found that verteporfin is cytotoxic for HR- cell lines. CONCLUSIONS: Our 350 gene set can be used to identify novel therapeutic targets and/or biomarkers conserved among acquired (e.g. due to inflammation) or intrinsic HR-independent BCa and PCa.