Alterations in programmed cell death pathways play a critical role in cancer development and maintenance. Yet the detailed mechanisms contributing to tumor initiation, progression, and therapeutic response in lung cancer remain incompletely understood. Also, models to study how changes in the cell death machinery impact tumor-immune interactions are limited. To address this, we describe two complementary murine models of lung adenocarcinoma that enable functional interrogation of cell death pathways in vivo. The first model is a clinically relevant, genetically engineered mouse model (GEMM) driven by KrasG12D activation and Tp53 loss, in which somatic CRISPR-Cas9-mediated gene editing permits tumor cell-specific knockout of candidate genes, facilitates in-depth studies of programmed cell death and immune signaling within 19 weeks. The second approach illustrates how a syngeneic orthotopic transplantation model can be used to study target genes and pathways that influence the tumor microenvironment and immunogenic cell death in a two-week timeframe. Together, these methods provide reproducible and versatile tools to investigate how modulation of cell death pathways impacts lung cancer development and progression and affects the tumor immune microenvironment, thus providing important information to guide the development of novel therapeutic strategies in lung cancer.

The adaptive immune system plays a critical role in the anti-tumor response. Understanding the crosstalk between these immune cell subsets could uncover novel therapeutic opportunities in non-small cell lung cancer (NSCLC). Single-cell RNA sequencing (scRNA-seq) and immune repertoire sequencing were applied to CD4+ T cells, CD8+ T cells, and B cells isolated from tumor and matched normal tissues of three NSCLC patients. Findings were validated using publicly available datasets. Naïve CD4+ T cells were the predominant cell type across samples, while effector memory and cycling T cells exhibited the most significant clonal expansion. Clonally expanded T and B cell populations were detected in tumor samples from all patients. Antibody-secreting cells showed the highest clonal overlap with atypical memory B cells, suggesting an extrafollicular differentiation pathway. Ligand-receptor analysis identified the CCL5-CCR1 signaling axis as a potential interaction pathway between atypical memory B cells and clonally expanded effector memory T cells. The integration of scRNA-seq and immune repertoire analysis provides a powerful tool to study the adaptive immune response in NSCLC. The CCL5-CCR1 axis may represent a novel mechanism linking T and B cell interactions in the tumor microenvironment, warranting further exploration for therapeutic targeting. Supported by the Austrian Research Promotion Agency (FFG). Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

BackgroundThe G protein-coupled receptor 55 (GPR55) is part of an expanded endocannabinoid system (ECS), and plays a pro-tumorigenic role in different cancer models, including pancreatic cancer. Next to cancer cells, various cells of the immune tumor microenvironment (TME) express receptors of the ECS that critically determine tumor growth. The role of GPR55 in cancer cells has been widely described, but its role in the immune TME is not well understood. MethodsWe intended to uncover the role of GPR55 in tumor immunity in a model of pancreatic ductal adenocarcinoma (PDAC). To this end, a KPCY tumor cell line or a GPR55-overexpressing KPCY cell line (KPCY55) from murine PDAC were subcutaneously injected into wildtype (WT) and GPR55 knockout (KO) mice, and immune cell populations were evaluated by flow cytometry. ResultsDeficiency of GPR55 in the TME led to reduced tumor weight and volume, and altered the immune cell composition of tumors, favoring an anti-tumorigenic environment by increasing the number of CD3+ T cells, particularly CD8+ T cells, and the expression of PDL1 on macrophages. RNA-seq pathway analysis revealed higher T cell activity in KPCY55 tumors of GPR55 KO vs. WT mice. In addition, tumors from GPR55 KO mice displayed increased levels of T cell chemokines Cxcl9 and Cxcl10. Migration of T cells from GPR55 KO mice towards CXCL9 was increased in comparison to T cells from WT mice, suggesting that a CXCR3/CXCL9 axis was involved in T cell influx into tumors of GPR55 KO mice. Notably, anti-PD-1 immunotherapy increased tumor burden in WT mice, while this effect was absent in the GPR55 KO mice. ConclusionOur study indicates that GPR55 in TME cells may drive tumor growth by suppressing T cell functions, such as migration, in a model of PDAC, making it an interesting target for immunotherapies.

BACKGROUND AND AIMS:Eosinophilic esophagitis (EoE) is a chronic, inflammatory, and antigen-driven disease of the esophagus. Total transcriptome data revealed alterations in the endocannabinoid system, in particular, down-regulation of monoacylglycerol lipase (MGL) in biopsies of patients with active EoE. We investigated the consequence of MGL down-regulation in mucosal biopsies of patients, and its implications for EoE development, such as recruitment of eosinophils. METHODS:Levels of MGL substrate 2-arachidonoylglycerol, MGL enzyme activity, and MGL colocalization with epithelial cells were determined in mucosal esophageal biopsies of patients with EoE. Supernatant of human primary esophageal epithelial cells was used to determine eosinophil migration and activation. An inducible mouse model of EoE was used to test MGL inhibition and cannabinoid (CB) receptor antagonism in vivo. RESULTS:MGL expression in esophageal epithelial cells from patients with active EoE is decreased, whereas 2-arachidonoylglycerol is increased compared with control subjects. Inhibition of MGL in epithelial cells leads to a proinflammatory phenotype capable of attracting eosinophils via CB2. Similarly, the EoE mouse model indicates that absence of MGL results in higher eosinophil infiltration. Targeting CB2 reduced the number of infiltrating eosinophils in the esophagi of mice. CONCLUSIONS:This study is the first of its kind to investigate the involvement of altered expression of endocannabinoid system components in EoE, and partly explains recent findings of more inflammatory features post EoE-treatment in cannabis users. Our findings could pave the way for research into alternative treatment options for EoE and call for caution regarding the use of cannabinoids in EoE.

Although recent advancements in immunotherapy have improved clinical outcomes, non-small cell lung cancer (NSCLC) is still the deadliest cancer type, as current treatments fail in many patients. This highlights a need for continued studies on this complex and multifaceted malignancy. The lung tumor microenvironment (TME) is marked by an infiltration of innate immune cells of the myeloid lineage, including macrophages and neutrophils, which affect patient outcomes. These cells induce inflammation and functional responses that can both promote and inhibit tumor growth and progression, with these functions being directly linked to their intracellular metabolism. The lung TME provides a milieu of signals, including cytokines and metabolites, that induce metabolic reprogramming in tumor-associated myeloid cells. Here, we review the present understanding of tumor-associated myeloid cell metabolism specifically in the context of NSCLC. Recent studies demonstrated that some metabolic pathways have the potential to be manipulated pharmacologically to eliminate or reprogram pathogenic, pro-tumor, and/or immunosuppressive myeloid cells to anti-tumor states for NSCLC therapies. Therefore, we highlight and propose potential metabolic targets in these myeloid cells, focusing on macrophages and neutrophils. These cells have direct roles in affecting subsequent responses of adaptive cells and their cellular metabolism must be further investigated to identify potential pharmacologic therapeutic targets. Targeting myeloid cell metabolism in the TME may be used in combination with the current regimen of immune checkpoint inhibition (ICI) and chemotherapy to improve outcomes for lung cancer patients.

The cytokine interleukin-10 (IL-10) limits the immune response and promotes resolution of acute inflammation. Because of its immunosuppressive effects, IL-10 up-regulation is a common feature of tumor progression and metastasis. Recently, IL-10 regulation has been shown to depend on mitochondria and redox-sensitive signals. We have found that Suppressor of site IIIQo Electron Leak 1.2 (S3QEL 1.2), a specific inhibitor of reactive oxygen species (ROS) production from mitochondrial complex III, and myxothiazol, a complex III inhibitor, decrease IL-10 in lipopolysaccharide (LPS)-activated macrophages. IL-10 down-regulation is likely to be mediated by suppression of c-Fos, which is a subunit of activator protein 1 (AP1), a transcription factor required for IL-10 gene expression. S3QEL 1.2 impairs IL-10 production in vivo after LPS challenge and promotes the survival of mice bearing B16F10 melanoma by lowering tumor growth. Our data identify a link between complex III-dependent ROS generation and IL-10 production in macrophages, the targeting of which could have potential in boosting antitumor immunity.

Macrophages are recruited to sites of infection contributing to the killing of bacteria, but also to malignant tumors, where they promote angiogenesis and suppress antitumor immune responses. The metabolic microenvironment in tumors is frequently depleted of important nutrients such as glucose. Here, we investigated metabolic adaptation strategies of macrophages to glucose deprivation using stable isotopic tracing. Lactate production was decreased, potentially indicating a reduction of glycolysis. In contrast, the contribution of glutamine to the tricarboxylic acid cycle via α-ketoglutarate and reductive carboxylation were increased. Moreover, gluconeogenesis, the reverse pathway of glycolysis, was activated in glucose-deprived macrophages, proceeding partially to the generation of glycolytic intermediates and glycerol-3-phosphate. The partial gluconeogenesis pathway was abrogated in human and murine macrophages lacking the initial gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PCK2, mitochondrial isoform). Partial gluconeogenesis was higher in anti-inflammatory, interleukin-4-stimulated compared to proinflammatory, interferon-γ/lipopolysaccharide-stimulated macrophages. Single-cell analysis and immunostaining revealed expression of PCK2 in macrophages from both lung cancer and normal lung. Low glucose conditions only partially modulated macrophage phenotypes, leading to reduced CD80 surface marker levels in proinflammatory, and enhanced vascular endothelial growth factor expression in anti-inflammatory macrophages. Our study reveals partial gluconeogenesis in glucose-deprived macrophages and shows that this versatile type of immune cells exhibits remarkable metabolic flexibility.

Successful early pregnancy depends on tightly regulated immune interactions at the feto-maternal interface to support the development of the semi-allogenic fetus. Neutrophils, key components of the innate immune system, play an underexplored role in this context. This study investigates neutrophil abundance, phenotype, function, and interactions in the extravillous trophoblast (EVT) invaded decidua during the first trimester of pregnancy (6–12 weeks gestation). Using high-dimensional flow cytometry and imaging mass cytometry, we identified three distinct neutrophil subsets within the decidua, each displaying unique maturation and activation profiles. Functional analyses revealed that neutrophil activation and degranulation, including granular protein release such as MPO, are critical for modulating the immune microenvironment and promoting EVT invasion. These findings highlight the central role of neutrophils in supporting proper placental development and their potential involvement in pregnancy complications if these processes are disrupted. This work underscores the importance of innate immune mechanisms in maternal-fetal health and early pregnancy success. Supported by FWF DK-MOLIN (W1241); OEAW (Doc Fellowship - 26477); DP-iDP (DOC-31); P35294; FFG-Bridge 1 grant (871284); and the OENB Anniversary Fund (17584) Immune Response Regulation: Cellular Mechanisms (IRC)

The presence of tumor-infiltrating B-cells is associated with survival in several solid tumors, including non-small cell lung cancer (NSCLC). However, B-cells in the tumor microenvironment (TME) exhibit both anti- and pro-tumorigenic roles, depending on the cellular and signaling context within the TME. Identifying and characterizing these phenotypes could be pivotal for modulating B-cell responses toward anti-tumor immunity. We analyzed high-dimensional protein and RNA expression data from B cells derived from lung, blood, and tumor samples of NSCLC patients. Clinical samples were analyzed through surface marker screening and flow cytometry to evaluate protein surface marker expression on TME B cells. Single-cell RNA sequencing was performed on sorted B cells from matched tumor and lung samples, and multiplex immunofluorescence (mIF) was used to study spatial localization and marker expression in tumor and adjacent lung regions of FFPE samples. Our study identified four B-cell subtypes within the NSCLC TME: plasma cells, memory B cells, germinal center (GC) B cells, and naive B cells. Differential expression of 11 markers on TME B cells was validated compared to those from lung and PBMCs. Notably, CD55 displayed differential mRNA and protein expression, with mIF data showing increased CD55 expression in GC areas of tertiary lymphoid structures (TLSs). This highlights CD55’s potential role in B-cell functions within the TME. Austrian Research Promotion Agency (FFG) Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)

The study of very early human placentation is largely limited due to ethical restrictions on the use of embryonic tissue and the fact that the placental anatomy of common laboratory animal models varies considerably from that of humans. In recent years several promising models, including trophoblast stem cell-derived organoids, have been developed that have also proven useful for the study of important trophoblast differentiation processes. However, the consideration of maternal blood flow in trophoblast invasion models currently appears to be limited to animal models. An almost forgotten model to study the invasive behavior of trophoblasts is to culture them in vitro on the chicken chorioallantoic membrane (CAM), showing an extraembryonic vascular network in its mesenchymal stroma that is continuously perfused by the chicken embryonic blood circulation.Here, we present an extension of the previously described ex ovo CAM assay and describe the use of cavity-bearing trophoblast spheroids obtained from the first trimester cell line ACH-3P. We demonstrate how spheroids penetrated the CAM and that erosion of CAM vessels by trophoblasts led to filling of the spheroid cavities with chicken blood, mimicking initial steps of intervillous space blood perfusion. Moreover, we prove that this model is useful for state-of-the-art techniques including immunofluorescence and in situ padlock probe hybridization, making it a versatile tool to study aspects of trophoblast invasion in presence of blood flow.

The tumor microenvironment (TME) is pivotal in cancer progression and the response to immunotherapy. A "hot" tumor typically contains immune cells that promote anti-tumor immunity, predicting positive prognosis. "Cold" tumors lack immune cells, suggesting a poor outlook across various cancers. Recent research has focused on converting "cold" tumors into "hot" tumors to enhance the success of immunotherapy. A prerequisite for the studies of the TME is an accurate knowledge of the cell populations of the TME. This study aimed to describe the immune TME of lung and colorectal cancer and melanoma, focusing on lymphoid and myeloid cell populations. We induced heterotopic immunocompetent tumors in C57BL/6 mice, using KP and LLC (Lewis lung carcinoma) cells for lung cancer, MC38 cells for colorectal cancer, and B16-F10 cells for melanoma. Immune cell infiltration was analyzed using multicolor flow cytometry in single-cell suspensions after tumor excision. KP cell tumors showed an abundance of neutrophils and eosinophils; however, they contained much less adaptive immune cells, while LLC cell tumors predominated in monocytes, neutrophils, and monocyte-derived dendritic cells. Monocytes and neutrophils, along with a significant T cell infiltration, were prevalent in MC38 tumors. Lastly, B16-F10 tumors were enriched in macrophages, while showing only moderate T cell presence. In conclusion, our data provide a detailed overview of the immune TME of various heterotopic tumors, highlighting the variabilities in the immune cell profiles of different tumor entities. Our data may be a helpful basis when investigating new immunotherapies, and thus, this report serves as a helpful tool for preclinical immunotherapy research design.

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. Significance Statement Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

BACKGROUND:Cancer immune evasion is critical in non-small cell lung cancer (NSCLC) and has been targeted by immunotherapy. High soluble (s)PD-L1 is associated with reduced survival and treatment failure in advanced stages. Here we evaluated the effects of sPD-L1 on T cells, relapse free survival, and overall survival in early stage NSCLC. METHODS:In vitro T cell stimulation was performed in the presence of sPD-L1 to evaluate its immunomodulatory activity. Data from The Cancer Genome Atlas (TCGA) were investigated for PD-L1 splice variants and enzymes involved in proteolytic cleavage (i.e. ADAM10). Plasma from 74 NSCLC (stage IA-IIIB), as well as an additional 73 (control cohort) patients was collected prior to curative surgery. Thereafter sPD-L1 levels from an immunosorbent assay were correlated with patient outcome. RESULTS:In vitro sPD-L1 inhibited IFN-γ production and proliferation of T cells and induced a terminal effector CD4 T cell subtype expressing CD27. Data from the TCGA demonstrated that elevated mRNA levels of ADAM10 is a negative predictor of outcome in NSCLC patients. To investigate the clinical relevance of these in vitro and TCGA findings, we quantified sPD-L1 in the plasma of early-stage NSCLC patients. In the first cohort we found significantly higher sPD-L1 levels in relapsing NSCLC patients, with a multivariate analysis revealing high sPD-L1 (>1000 pg/mL) as an independent predictor of survival. However, these findings could not be validated in two independent control cohorts. DISCUSSION:Although in vitro and TCGA data support the suppressive effect of sPD-L1 we were unable to translate this in our clinical setting. These results may be due to the small patient number and their heterogeneity as well as the lack of a standardized sPD-L1 ELISA. Our inconclusive results regarding the value of sPD-L1 in early stage NSCLC warrant assay validation and further investigation in larger (neo-)adjuvant trials.

Introduction Pro- and anticoagulant mechanisms play an important role during gestation to guarantee a successful implantation of the blastocyst, but also when it comes to term to avoid haemorrhage [1] [2]. Pregnancy is a state of hypercoagulation and platelets underlie certain dynamic changes during pregnancy, like a decrease of the platelet count towards the end of pregnancy [3]. Previous studies revealed that adherence of maternal platelets to the placental villous surface is a common process even in very early stages of gestation, and therefore a tightly regulated cross talk between platelets and the placenta seems to be of high importance [4].