An optimized disaggregation method for human lung tumors that preserves the phenotype and function of the immune cells

Extraction and characterization of exosomes from the exhaled breath condensate and sputum of lung cancer patients and vulnerable tobacco consumers-potential noninvasive diagnostic biomarker source

Noninvasive sample sources of exosomes, such as exhaled breath and sputum, which are in close proximity to the tumor microenvironment and may contain biomarkers indicative of lung cancer, are far more permissive than invasive sample sources for biomarker screening. Standardized exosome extraction and characterization approaches for low-volume noninvasive samples are critically needed. We isolated and characterized exhaled breath condensate (EBC) and sputum exosomes from healthy nonsmokers (n= 30), tobacco smokers (n= 30), and lung cancer patients (n= 40) and correlated the findings with invasive sample sources. EBC samples were collected by using commercially available R-Tubes. To collect sputum samples the participants were directed to take deep breaths, hold their breath, and cough in a collection container. Dynamic light scattering, nanoparticle tracking analysis, and transmission electron microscopy were used to evaluate the exosome morphology. Protein isolation, western blotting, exosome quantification via EXOCET, and Fourier transform infrared spectroscopy were performed for molecular characterization. Exosomes were successfully isolated from EBC and sputum samples, and their yields were adequate and sufficiently pure for subsequent downstream processing and characterization. The exosomes were confirmed based on their size, shape, and surface marker expression. Remarkably, cancer exosomes were the largest in size not only in the plasma subgroups, but also in the EBC (p < 0.05) and sputum (p= 0.0036) subgroups, according to our findings. A significant difference in exosome concentrations were observed between the control sub-groups (p < 0.05). Our research confirmed that exosomes can be extracted from noninvasive sources, such as EBC and sputum, to investigate lung cancer diagnostic biomarkers for research, clinical, and early detection in smokers.

Human Tumor-Associated Macrophages and Neutrophils Regulate Antitumor Antibody Efficacy through Lethal and Sublethal Trogocytosis

The clinical benefits of tumor-targeting antibodies (tAb) are modest in solid human tumors. The efficacy of many tAbs is dependent on Fc receptor (FcR)-expressing leukocytes that bind Fc fragments of tAb. Tumor-associated macrophages (TAM) and neutrophils (TAN) represent the majority of FcR+ effectors in solid tumors. A better understanding of the mechanisms by which TAMs and TANs regulate tAb response could help improve the efficacy of cancer treatments. Here, we found that myeloid effectors interacting with tAb-opsonized lung cancer cells used antibody-dependent trogocytosis (ADT) but not antibody-dependent phagocytosis. During this process, myeloid cells "nibbled off" tumor cell fragments containing tAb/targeted antigen (tAg) complexes. ADT was only tumoricidal when the tumor cells expressed high levels of tAg and the effectors were present at high effector-to-tumor ratios. If either of these conditions were not met, which is typical for solid tumors, ADT was sublethal. Sublethal ADT, mainly mediated by CD32hiCD64hi TAM, led to two outcomes: (i) removal of surface tAg/tAb complexes from the tumor that facilitated tumor cell escape from the tumoricidal effects of tAb; and (ii) acquisition of bystander tAgs by TAM with subsequent cross-presentation and stimulation of tumor-specific T-cell responses. CD89hiCD32loCD64lo peripheral blood neutrophils (PBN) and TAN stimulated tumor cell growth in the presence of the IgG1 anti-EGFR Ab cetuximab; however, IgA anti-EGFR Abs triggered the tumoricidal activity of PBN and negated the stimulatory effect of TAN. Overall, this study provides insights into the mechanisms by which myeloid effectors mediate tumor cell killing or resistance during tAb therapy.

SIGNIFICANCE

The elucidation of the conditions and mechanisms by which human FcR+ myeloid effectors mediate cancer cell resistance and killing during antibody treatment could help develop improved strategies for treating solid tumors.

Single-Cell Transcriptomic Profiling Identifies Molecular Phenotypes of Newborn Human Lung Cells

While animal model studies have extensively defined the mechanisms controlling cell diversity in the developing mammalian lung, there exists a significant knowledge gap with regards to late-stage human lung development. The NHLBI Molecular Atlas of Lung Development Program (LungMAP) seeks to fill this gap by creating a structural, cellular and molecular atlas of the human and mouse lung. Transcriptomic profiling at the single-cell level created a cellular atlas of newborn human lungs. Frozen single-cell isolates obtained from two newborn human lungs from the LungMAP Human Tissue Core Biorepository, were captured, and library preparation was completed on the Chromium 10X system. Data was analyzed in Seurat, and cellular annotation was performed using the ToppGene functional analysis tool. Transcriptional interrogation of 5500 newborn human lung cells identified distinct clusters representing multiple populations of epithelial, endothelial, fibroblasts, pericytes, smooth muscle, immune cells and their gene signatures. Computational integration of data from newborn human cells and with 32,000 cells from postnatal days 1 through 10 mouse lungs generated by the LungMAP Cincinnati Research Center facilitated the identification of distinct cellular lineages among all the major cell types. Integration of the newborn human and mouse cellular transcriptomes also demonstrated cell type-specific differences in maturation states of newborn human lung cells. Specifically, newborn human lung matrix fibroblasts could be separated into those representative of younger cells (n = 393), or older cells (n = 158). Cells with each molecular profile were spatially resolved within newborn human lung tissue. This is the first comprehensive molecular map of the cellular landscape of neonatal human lung, including biomarkers for cells at distinct states of maturity.

Mononuclear myeloid cells can shape neutrophils in brain tumors

In most human solid cancer types, a high frequency of intratumoral neutrophils is associated with poor prognosis. In a recent study, Maas et al. identified an intratumoral niche in which mononuclear myeloid cells drive proinflammatory neutrophil activation in brain tumors. This study sheds new light on the intratumoral modulation of neutrophils.

Impact of enzymatic digestion on single cell suspension yield from peripheral human lung tissue

An increasing number of translational investigations of lung biology rely on analyzing single cell suspensions obtained from human lungs. To obtain these single cell suspensions, human lungs from biopsies or research-consented organ donors must be subjected to mechanical and enzymatic digestion prior to analysis with either flow cytometry or single cell RNA sequencing. A variety of enzymes have been used to perform tissue digestion, each with potential limitations. To better understand the limitations of each enzymatic digestion protocol and to establish a framework for comparing studies across protocols, we performed five commonly published protocols in parallel from identical samples obtained from 6 human lungs. Following mechanical (gentleMACS™) and enzymatic digestion, we quantified cell count and viability using a Nexcelom Cellometer and determined cell phenotype using multiparameter spectral flow cytometry (Cytek™ Aurora). We found that all protocols were superior in cellular yield and viability when compared to mechanical digestion alone. Protocols high in dispase cleaved immune markers CD4, CD8, CD69, and CD103 and contributed to an increased monocyte to macrophage yield. Similarly, dispase led to a differential epithelial cell yield, with increased TSPN8+ and ITGA6+ epithelial cells and reduced CD66e+ cells. When compared to collagenase D, collagenase P protocols yielded increased AT1 and AT2 cells and decreased endothelial cells. These results provide a framework for selecting an enzymatic digestion protocol best suited to the scientific question and allow for comparison of studies using different protocols.

Surgical Inflammation Alters Immune Response to Intraoperative Photodynamic Therapy

Surgical cytoreduction for patients with malignant pleural mesothelioma (MPM) is used for selected patients as a part of multi-modality management strategy. Our group has previously described the clinical use of photodynamic therapy (PDT), a form of non-ionizing radiation, as an intraoperative therapy option for MPM. Although necessary for the removal of bulk disease, the effects of surgery on residual MPM burden are not understood. In this bedside-to-bench study, Photofrin-based PDT introduced the possibility of achieving a long-term response in murine models of MPM tumors that were surgically debulked by 60% to 90%. Thus, the addition of PDT provided curative potential after an incomplete resection. Despite this success, we postulated that surgical induction of inflammation may mitigate the comprehensive response of residual disease to further therapy. Utilizing a previously validated tumor incision (TI) model, we demonstrated that the introduction of surgical incisions had no effect on acute cytotoxicity by PDT. However, we found that surgically induced inflammation limited the generation of antitumor immunity by PDT. Compared with PDT alone, when TI preceded PDT of mouse tumors, splenocytes and/or CD8+ T cells from the treated mice transferred less antitumor immunity to recipient animals. These results demonstrate that addition of PDT to surgical cytoreduction significantly improves long-term response compared with cytoreduction alone, but at the same time, the inflammation induced by surgery may limit the antitumor immunity generated by PDT. These data inform future potential approaches aimed at blocking surgically induced immunosuppression that might improve the outcomes of intraoperative combined modality treatment.

Significance

Although mesothelioma is difficult to treat, we have shown that combining surgery with a form of radiation, photodynamic therapy, may help people with mesothelioma live longer. In this study, we demonstrate in mice that this regimen could be further improved by addressing the inflammation induced as a by-product of surgery.

Preparation of a Single-Cell Suspension from Tumor Biopsy Samples for Single-Cell RNA Sequencing

An essential requirement for single-cell RNA sequencing in cancer is the preparation of high-quality single-cell suspensions from the tumor tissue. In this work, various methods of dissociation of tumor biopsy specimens were analyzed and developed to obtain a cell suspension with at least 80% viability. It was found that the optimal conditions for sample preparation are mechanical dissociation followed by incubation with a collagenase/hyaluronidase mixture with addition of DNAase I for 60 min. Thus, we optimize the approach for preparing single-cell suspensions from the tumor biopsy tissue for single-cell RNA sequencing.

B cell-dependent subtypes and treatment-based immune correlates to survival in stage 3 and 4 lung adenocarcinomas

Lung cancer is the leading cause of cancer-related deaths worldwide. Surgery and chemoradiation are the standard of care in early stages of non-small cell lung cancer (NSCLC), while immunotherapy is the standard of care in late-stage NSCLC. The immune composition of the tumor microenvironment (TME) is recognized as an indicator for responsiveness to immunotherapy, although much remains unknown about its role in responsiveness to surgery or chemoradiation. In this pilot study, we characterized the NSCLC TME using mass cytometry (CyTOF) and bulk RNA sequencing (RNA-Seq) with deconvolution of RNA-Seq being performed by Kassandra, a recently published deconvolution tool. Stratification of patients based on the intratumoral abundance of B cells identified that the B-cell rich patient group had increased expression of CXCL13 and greater abundance of PD1+ CD8 T cells. The presence of B cells and PD1+ CD8 T cells correlated positively with the presence of intratumoral tertiary lymphoid structures (TLS). We then assessed the predictive and prognostic utility of these cell types and TLS within publicly available stage 3 and 4 lung adenocarcinoma (LUAD) RNA-Seq datasets. As previously described by others, pre-treatment expression of intratumoral 12-chemokine TLS gene signature is associated with progression free survival (PFS) in patients who receive treatment with immune checkpoint inhibitors (ICI). Notably and unexpectedly pre-treatment percentages of intratumoral B cells are associated with PFS in patients who receive surgery, chemotherapy, or radiation. Further studies to confirm these findings would allow for more effective patient selection for both ICI and non-ICI treatments.

Strategies for optimizing CITE-seq for human islets and other tissues

Defining the immunological landscape of human tissue is an important area of research, but challenges include the impact of tissue disaggregation on cell phenotypes and the low abundance of immune cells in many tissues. Here, we describe methods to troubleshoot and standardize Cellular Indexing of Transcriptomes and Epitopes by sequencing (CITE-seq) for studies involving enzymatic digestion of human tissue. We tested epitope susceptibility of 92 antibodies commonly used to differentiate immune lineages and cell states on human peripheral blood mononuclear cells following treatment with an enzymatic digestion cocktail used to isolate islets. We observed CD4, CD8a, CD25, CD27, CD120b, CCR4, CCR6, and PD1 display significant sensitivity to enzymatic treatment, effects that often could not be overcome with alternate antibodies. Comparison of flow cytometry-based CITE-seq antibody titrations and sequencing data supports that for the majority of antibodies, flow cytometry accurately predicts optimal antibody concentrations for CITE-seq. Comparison by CITE-seq of immune cells in enzymatically digested islet tissue and donor-matched spleen not treated with enzymes revealed little digestion-induced epitope cleavage, suggesting increased sensitivity of CITE-seq and/or that the islet structure may protect resident immune cells from enzymes. Within islets, CITE-seq identified immune cells difficult to identify by transcriptional signatures alone, such as distinct tissue-resident T cell subsets, mast cells, and innate lymphoid cells (ILCs). Collectively this study identifies strategies for the rational design and testing of CITE-seq antibodies for single-cell studies of immune cells within islets and other tissues.

Capabilities of Single Cell ICP-MS for the Analysis of Cell Suspensions from Solid Tissues

Single cell elemental (SC) analysis of isogenic cell cultures can be done using inductively coupled plasma (ICP-MS) detection. However, 2D cell cultures are just models to simplify the complexity of real tissue samples. Here, we show for the first time the capabilities of the technique (SC-ICP-MS) to analyze single cell suspensions of isolated cells from tissues. An optimized cocktail of proteolytic and collagenolytic enzymes was applied in a single preparation step with cellular yields up to 28% using 0.5 g of fresh rat spleen and liver, respectively. The retrieved cells revealed adequate morphology and stability to be examined by SC-ICP-MS. Quantitative elemental analysis of P, S, Cu, and Fe from disaggregated cells from rat spleen and liver tissues revealed levels of Fe of 7-16 fg/cell in the spleen and 8-12 fg/cell in the liver, while Cu was about 3-5 fg/cell in the spleen and 1.5-2.5 fg/cell in the liver. Evaluation of the transmembrane protein transferrin receptor 1 (TfR1) expression levels in disaggregated cells was also conducted by using a Nd-labelled antibody against this cell surface biomarker. Quantitative results showed significantly lower expression in the disaggregated cells than in the cell model HepG2, in agreement with the overexpression of this biomarker in tumor cells. In this proof of concept study, the tissue disaggregation protocol has shown to maintain the elemental intracellular content of cells as well as the presence of relevant antigens. This opens a completely new area of research for SC-ICP-MS in tissue samples as a complementary strategy with validation capabilities.

Tumor factors stimulate lysosomal degradation of tumor antigens and undermine their cross-presentation in lung cancer

Activities of dendritic cells (DCs) that present tumor antigens are often suppressed in tumors. Here we report that this suppression is induced by tumor microenvironment-derived factors, which activate the activating transcription factor-3 (ATF3) transcription factor and downregulate cholesterol 25-hydroxylase (CH25H). Loss of CH25H in antigen presenting cells isolated from human lung tumors is associated with tumor growth and lung cancer progression. Accordingly, mice lacking CH25H in DCs exhibit an accelerated tumor growth, decreased infiltration and impaired activation of intratumoral CD8+ T cells. These mice do not establish measurable long-term immunity against malignant cells that undergo chemotherapy-induced immunogenic cell death. Mechanistically, downregulation of CH25H stimulates membrane fusion between endo-phagosomes and lysosomes, accelerates lysosomal degradation and restricts cross-presentation of tumor antigens in the intratumoral DCs. Administration of STING agonist MSA-2 reduces the lysosomal activity in DCs, restores antigen cross presentation, and increases therapeutic efficacy of PD-1 blockade against tumour challenge in a CH25H-dependent manner. These studies highlight the importance of downregulation of CH25H in DCs for tumor immune evasion and resistance to therapy.

Epithelial cell size dysregulation in human lung adenocarcinoma

Human cells tightly control their dimensions, but in some cancers, normal cell size control is lost. In this study we measure cell volumes of epithelial cells from human lung adenocarcinoma progression in situ. By leveraging artificial intelligence (AI), we reconstruct tumor cell shapes in three dimensions (3D) and find airway type 2 cells display up to 10-fold increases in volume. Surprisingly, cell size increase is not caused by altered ploidy, and up to 80% of near-euploid tumor cells show abnormal sizes. Size dysregulation is not explained by cell swelling or senescence because cells maintain cytoplasmic density and proper organelle size scaling, but is correlated with changes in tissue organization and loss of a novel network of processes that appear to connect alveolar type 2 cells. To validate size dysregulation in near-euploid cells, we sorted cells from tumor single-cell suspensions on the basis of size. Our study provides data of unprecedented detail for cell volume dysregulation in a human cancer. Broadly, loss of size control may be a common feature of lung adenocarcinomas in humans and mice that is relevant to disease and identification of these cells provides a useful model for investigating cell size control and consequences of cell size dysregulation.

Murine myeloid derived suppressor cells possess a range of suppressive mechanisms-Granzyme B is not among them

This paper addresses the controversy of Granzyme B (GzmB) expression by murine Myeloid Derived Suppressor Cells (MDSCs). MDSCs are a heterogenous immature myeloid population that are generated in chronic inflammatory pathologies for the purpose to suppress inflammatory responses. MDSCs express a multitude of factors to induce suppressive function such as PD-L1, reactive oxygen species (ROS), nitric oxide synthase (iNOS), and Arginase-1. Recently, Dufait et al. sought to demonstrate GzmB as an additional mechanism for suppression by MDSCs. They reported that murine MDSCs not only significantly express GzmB as well as Perforin (Prf1), but this expression is functionally important for tumor growth in vivo as well as tumor migration in vitro. We conducted experiments to address the same question but made confounding observations: MDSCs under stringent developmental process do not express GzmB. Our results show that not only GzmB protein is not produced at functional level, but the mRNA transcript is not detectable either. In fact, the GzmB protein found in the media of MDSC culture was due to T cells or natural killer cells contained in bone marrow and cultured alongside MDSCs. We strengthen this finding by genetically deleting GzmB from the myeloid lineage and measuring tumor burden compared to WT counterpart. Our results show no significant difference in tumor burden, suggesting that even if there is minor expression of GzmB, it is not produced at a functional amount to affect tumor growth. Therefore, this paper proposes alternative theories that align with the known understanding of GzmB expression and secretion.

Protocol for fluorescence-activated cell sorting of human EpCAM+ lung cancer cells for gene expression analysis of Rac guanine-nucleotide exchange factors

Here, we describe a protocol for fluorescence-activated cell sorting (FACS) of human EpCAM+ cells from fresh surgically resected specimens. We then use Q-PCR to identify specific molecular targets associated with the metastatic phenotype. This combined approach enables a qualitative and quantitative gene expression analysis of lung cancer samples. We describe how to use the protocol for Rac GEFs, but it can be applied broadly to other molecular targets. For complete details on the use and execution of this protocol, please refer to Cooke et al. (2021) and Quatromoni et al. (2015).

Automated–Mechanical Procedure Compared to Gentle Enzymatic Tissue Dissociation in Cell Function Studies

The first step to obtain a cellular suspension from tissues is the disaggregation procedure. The cell suspension method has to provide a representative sample of the different cellular subpopulations and to maximize the number of viable functional cells. Here, we analyzed specific cell functions in cell suspensions from several rat tissues obtained by two different methods, automated–mechanical and enzymatic disaggregation. Flow cytometric, confocal, and ultrastructural (TEM) analyses were applied to the spleen, testis, liver and other tissues. Samples were treated by an enzymatic trypsin solution or processed by the Medimachine II (MMII). The automated–mechanical and enzymatic disaggregation procedures have shown to work similarly in some tissues, which displayed comparable amounts of apoptotic/necrotic cells. However, cells obtained by the enzyme-free Medimachine II protocols show a better preservation lysosome and mitochondria labeling, whereas the enzymatic gentle dissociation appears to constantly induce a lower amount of intracellular ROS; nevertheless, lightly increased ROS can be recognized as a complimentary signal to promote cell survival. Therefore, MMII represents a simple, fast, and standardized method for tissue processing, which allows to minimize bias arising from the operator’s ability. Our study points out technical issues to be adopted for specific organs and tissues to obtain functional cells.

Adjuvant Photodynamic Therapy, Mediated via Topical Versus Systemic Administration of 5-Aminolevulinic Acid for Control of Murine Mammary Tumor after Surgical Resection

Treatment de-escalation is sought in the management of precursor lesions of early stage breast cancer, driving the appeal of adjuvant modalities to lumpectomy that reduce toxicity and minimally detract from patient quality of life. We investigate photodynamic therapy (PDT), with the photosensitizing prodrug, 5-aminolevulinic acid (ALA), as adjuvant therapy to complete resection of murine mammary tumor (propagated from TUBO cells). ALA was delivered either systemically (oral, 250 mg kg^-1 ) at 5 h before 632 nm illumination or topically (20% solution) to the resection site at 10 min before light delivery to 135 J cm^-2 . Treatment with either oral-ALA-PDT (oALA-PDT) or topical-ALA-PDT (tALA-PDT) to the mammary fat pad after TUBO complete resection (CR) produced long-term tumor control with 90-day complete response rates of 21% and 32%, respectively, compared to control rates of 0-5% in mice receiving only CR. Thus, CR/tALA-PDT was equipotent to CR/oALA-PDT despite ~10-fold lower levels of ALA-induced protoporphyrin XI as photosensitizer after topical versus oral-ALA administration. CR/oALA-PDT produced more vascular damage, greater proportion of tissue-resident neutrophils and stronger inflammation when compared to CR/tALA-PDT. Collectively, these data provide rationale for ongoing investigation of ALA-PDT as adjuvant therapy after lumpectomy for increased probability of local control in the treatment of breast cancer.

FARP1, ARHGEF39, and TIAM2 are essential receptor tyrosine kinase effectors for Rac1-dependent cell motility in human lung adenocarcinoma

Despite the undisputable role of the small GTPase Rac1 in the regulation of actin cytoskeleton reorganization, the Rac guanine-nucleotide exchange factors (Rac-GEFs) involved in Rac1-mediated motility and invasion in human lung adenocarcinoma cells remain largely unknown. Here, we identify FARP1, ARHGEF39, and TIAM2 as essential Rac-GEFs responsible for Rac1-mediated lung cancer cell migration upon EGFR and c-Met activation. Noteworthily, these Rac-GEFs operate in a non-redundant manner by controlling distinctive aspects of ruffle dynamics formation. Mechanistic analysis reveals a leading role of the AXL-Gab1-PI3K axis in conferring pro-motility traits downstream of EGFR. Along with the positive association between the overexpression of Rac-GEFs and poor lung adenocarcinoma patient survival, we show that FARP1 and ARHGEF39 are upregulated in EpCam⁺ cells sorted from primary human lung adenocarcinomas. Overall, our study reveals fundamental insights into the complex intricacies underlying Rac-GEF-mediated cancer cell motility signaling, hence underscoring promising targets for metastatic lung cancer therapy.

MDSC in Mice and Men: Mechanisms of Immunosuppression in Cancer

Myeloid-derived suppressor cells (MDSCs) expand during pathological conditions in both humans and mice and their presence is linked to poor clinical outcomes for cancer patients. Studying MDSC immunosuppression is restricted by MDSCs’ rarity, short lifespan, heterogeneity, poor viability after freezing and the lack of MDSC-specific markers. In this review, we will compare identification and isolation strategies for human and murine MDSCs. We will also assess what direct and indirect immunosuppressive mechanisms have been attributed to MDSCs. While some immunosuppressive mechanisms are well-documented in mice, e.g., generation of ROS, direct evidence is still lacking in humans. In future, bulk or single-cell genomics could elucidate which phenotypic and functional phenotypes MDSCs adopt in particular microenvironments and help to identify potential targets for therapy.

Analysis of Intra-Tumoral Macrophages and T Cells in Non-Small Cell Lung Cancer (NSCLC) Indicates a Role for Immune Checkpoint and CD200-CD200R Interactions

Non-small cell lung carcinoma (NSCLC) is one of the most commonly diagnosed cancers and a leading cause of cancer-related deaths. Immunotherapy with immune checkpoint inhibitors shows beneficial responses, but only in a proportion of patients. To improve immunotherapy in NSCLC, we need to map the immune checkpoints that contribute immunosuppression in NSCLC-associated immune cells and to identify novel pathways that regulate immunosuppression. Here, we investigated the gene expression profiles of intra-tumoral immune cells isolated from NSCLC patients and compared them to the expression profiles of their counterparts in adjacent healthy tissue. Transcriptome analysis was performed on macrophages, CD4+ and CD8+ T cells. The data was subjected to Gene Ontology (GO) term enrichment and weighted correlation network analysis in order to identify mediators of immunosuppression in the tumor microenvironment in NSCLC. Immune cells from NSCLC revealed a consistent differential expression of genes involved in interactions between myeloid cells and lymphocytes. We further identified several immunosuppressive molecules and pathways that may be activated in tumor-associated macrophages in NSCLC. Importantly, we report novel data on immune cell expression of the newly described CD200/CD200R1 pathway, and the leukocyte immunoglobulin-like receptors (LILRs), which may represent novel innate immune checkpoints, dampening the anti-tumor T cell immune response in NSCLC. Our study substantiates the importance of tumor-associated macrophages as a mediator of immunosuppression and a promising target for immunotherapy.

Analysis of classical neutrophils and polymorphonuclear myeloid-derived suppressor cells in cancer patients and tumor-bearing mice

In this study, using single-cell RNA-seq, cell mass spectrometry, flow cytometry, and functional analysis, we characterized the heterogeneity of polymorphonuclear neutrophils (PMNs) in cancer. We describe three populations of PMNs in tumor-bearing mice: classical PMNs, polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and activated PMN-MDSCs with potent immune suppressive activity. In spleens of mice, PMN-MDSCs gradually replaced PMNs during tumor progression. Activated PMN-MDSCs were found only in tumors, where they were present at the very early stages of the disease. These populations of PMNs in mice could be separated based on the expression of CD14. In peripheral blood of cancer patients, we identified two distinct populations of PMNs with characteristics of classical PMNs and PMN-MDSCs. The gene signature of tumor PMN-MDSCs was similar to that in mouse activated PMN-MDSCs and was closely associated with negative clinical outcome in cancer patients. Thus, we provide evidence that PMN-MDSCs are a distinct population of PMNs with unique features and potential for selective targeting opportunities.

Neoadjuvant Gene-Mediated Cytotoxic Immunotherapy for Non-Small-Cell Lung Cancer: Safety and Immunologic Activity

Gene-mediated cytotoxic immunotherapy (GMCI) is an immuno-oncology approach involving local delivery of a replication-deficient adenovirus expressing herpes simplex thymidine kinase (AdV-tk) followed by anti-herpetic prodrug activation that promotes immunogenic tumor cell death, antigen-presenting cell activation, and T cell stimulation. This phase I dose-escalation pilot trial assessed bronchoscopic delivery of AdV-tk in patients with suspected lung cancer who were candidates for surgery. A single intra-tumoral AdV-tk injection in three dose cohorts (maximum 1012 viral particles) was performed during diagnostic staging, followed by a 14-day course of the prodrug valacyclovir, and subsequent surgery 1 week later. Twelve patients participated after appropriate informed consent. Vector-related adverse events were minimal. Immune biomarkers were evaluated in tumor and blood before and after GMCI. Significantly increased infiltration of CD8+ T cells was found in resected tumors. Expression of activation, inhibitory, and proliferation markers, such as human leukocyte antigen (HLA)-DR, CD38, Ki67, PD-1, CD39, and CTLA-4, were significantly increased in both the tumor and peripheral CD8+ T cells. Thus, intratumoral AdV-tk injection into non-small-cell lung cancer (NSCLC) proved safe and feasible, and it effectively induced CD8+ T cell activation. These data provide a foundation for additional clinical trials of GMCI for lung cancer patients with potential benefit if combined with other immune therapies.

Folate Receptor Beta Designates Immunosuppressive Tumor-Associated Myeloid Cells That Can Be Reprogrammed with Folate-Targeted Drugs

Although immunotherapies of tumors have demonstrated promise for altering the progression of malignancies, immunotherapies have been limited by an immunosuppressive tumor microenvironment (TME) that prevents infiltrating immune cells from performing their anticancer functions. Prominent among immunosuppressive cells are myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM) that inhibit T cells via release of immunosuppressive cytokines and engagement of checkpoint receptors. Here, we explore the properties of MDSCs and TAMs from freshly isolated mouse and human tumors and find that an immunosuppressive subset of these cells can be distinguished from the nonimmunosuppressive population by its upregulation of folate receptor beta (FRβ) within the TME and its restriction to the TME. This FRβ+ subpopulation could be selectively targeted with folate-linked drugs. Delivery of a folate-targeted TLR7 agonist to these cells (i) reduced their immunosuppressive function, (ii) increased CD8+ T-cell infiltration, (iii) enhanced M1/M2 macrophage ratios, (iv) inhibited tumor growth, (v) blocked tumor metastasis, and (vi) improved overall survival without demonstrable toxicity. These data reveal a broadly applicable strategy across tumor types for reprogramming MDSCs and TAMs into antitumorigenic immune cells using a drug that would otherwise be too toxic to administer systemically. The data also establish FRβ as the first marker that distinguishes immunosuppressive from nonimmunosuppressive subsets of MDSCs and TAMs. Because all solid tumors accumulate MDSCs and TAMs, a general strategy to both identify and reprogram these cells should be broadly applied in the characterization and treatment of multiple tumors. SIGNIFICANCE: FRβ serves as both a means to identify and target MDSCs and TAMs within the tumor, allowing for delivery of immunomodulatory compounds to tumor myeloid cells in a variety of cancers.

Addition of anti-TIM3 or anti-TIGIT Antibodies to anti-PD1 Blockade Augments Human T cell Adoptive Cell Transfer

PD1 blockade to reinvigorate T cells has become part of standard of care for patients with NSCLC across disease stages. However, the majority of patients still do not respond. One potential mechanism of resistance is increased expression of other checkpoint inhibitory molecules on T cells leading to their suppression; however, this phenomenon has not been well studied in tumor-reactive, human T cells. The purpose of this study was to evaluate this compensatory mechanism in a novel model using human effector T cells infiltrating and reactive against human lung cancer. Immunodeficient mice with flank tumors established from a human lung cancer cell line expressing the NYESO1 antigen were treated with activated human T cells expressing a TCR reactive to NYESO1 (Ly95) with or without anti-PD1 alone and with combinations of anti-PD1 plus anti-TIM3 or anti-TIGIT. A month later, the effect on tumor growth and the phenotype and ex vivo function of the TILs were analyzed. Anti-PD1 and Ly95 T cells led to greater tumor control than Ly95 T cells alone; however, tumors continued to grow. The ex-vivo function of PD1-blocked Ly95 TILs was suppressed and was associated with increased T cell expression of TIM3/TIGIT. Administering combinatorial blockade of PD1+ TIM3 or PD1+ TIGIT with Ly95 T cells led to greater tumor control than blocking PD1 alone. In our model, PD1 blockade was suboptimally therapeutic alone. The effect of TIM3 and TIGIT was upregulated on T cells in response to PD1 blockade and anti-tumor activity could be enhanced when these inhibitory receptors were also blocked with antibodies in combination with anti-PD1 therapy.

Follicular cytotoxic CD8 T cells present high cytokine expression, and are more susceptible to Breg-mediated suppression in non-small cell lung cancer

Tumor-infiltrating CD8 T cells are instrumental to antitumor immunity. In this study, we found that a subset of CXCR5-expressing CD8 T cells, termed follicular cytotoxic T (Tfc) cells, potently infiltrated the untreated tumors from non-small cell lung cancer (NSCLC) patients. On average, Tfc cells represented 14% of total tumor-infiltrating CD8 T cells and 6.6% of total tumor-infiltrating lymphocytes. Upon antigenic stimulation, Tfc cells presented significantly higher degranulation and stronger release of proinflammatory cytokines, including IFNg, IL2, and TNF, and the pleiotropic cytokine IL10 than non-Tfc cells. However, the expression of granzyme B and perforin was significantly lower in Tfc cells than in non-Tfc CD8 T cells. B regulatory (Breg) cells could significantly suppress proinflammatory cytokine production in both Tfc cells and non-Tfc CD8 T cells, but in Tfc cells, a lower concentration was required. Moreover, Breg cells could significantly elevate IL10 expression by Tfc cells but could not affect IL-10 expression by non-Tfc CD8 T cells. The neutralization of IL10 significantly reduced the extent of Breg-mediated regulation. Together, this study demonstrated that Tfc cells represented a significant proportion of tumor-infiltrating CD8 T cells in lung carcinoma. These Tfc cells were different from non-Tfc CD8 T cells in terms of cytokine expression and granzyme and perforin release and were more susceptible to Breg-mediated suppression in an IL-10-dependent manner.

A phenotypic switch in the dispersal strategy of breast cancer cells selected for metastatic colonization

An important question in cancer evolution concerns which traits make a cell likely to successfully metastasize. Cell motility phenotypes, mediated by cell shape change, are strong candidates. We experimentally evolved breast cancer cells in vitro for metastatic capability, using selective regimes designed to simulate stages of metastasis, then quantified their motility behaviours using computer vision. All evolved lines showed changes to motility phenotypes, and we have identified a previously unknown density-dependent motility phenotype only seen in cells selected for colonization of decellularized lung tissue. These cells increase their rate of morphological change with an increase in migration speed when local cell density is high. However, when the local cell density is low, we find the opposite relationship: the rate of morphological change decreases with an increase in migration speed. Neither the ancestral population, nor cells selected for their ability to escape or invade extracellular matrix-like environments, displays this dynamic behavioural switch. Our results suggest that cells capable of distant-site colonization may be characterized by dynamic morphological phenotypes and the capacity to respond to the local social environment.

TIPE2 specifies the functional polarization of myeloid-derived suppressor cells during tumorigenesis

Myeloid-derived suppressor cells (MDSCs) are "polarized" myeloid cells that effectively promote tumorigenesis by inhibiting antitumor immunity. How myeloid cells acquire the protumoral properties during tumorigenesis is poorly understood. We report here that the polarity protein TIPE2 (tumor necrosis factor-α-induced protein 8-like 2) mediates the functional polarization of murine and human MDSCs by specifying their pro- and antitumoral properties. Tumor cells induced the expression of TIPE2 in Gr1+CD11b+ cells through reactive oxygen species (ROS). TIPE2 in turn increased the expression of protumoral mediators such as CCAAT/enhancer-binding protein-β while inhibiting the expression of antitumoral mediators. Consequently, tumor growth in TIPE2-deficient mice was significantly diminished, and TIPE2-deficient MDSCs markedly inhibited tumor growth upon adoptive transfer. Pharmaceutical blockade of ROS inhibited TIPE2 expression in MDSCs and reduced tumor growth in mice. These findings indicate that TIPE2 plays a key role in the functional polarization of MDSCs and represents a new therapeutic target for cancer immunotherapy.

Patients Lung Derived Tumoroids (PLDTs) to model therapeutic response

Preclinical lung cancer models are essential for a basic understanding of lung cancer biology and its translation into efficient treatment options for affected patients. Lung cancer cell lines and xenografts derived directly from human lung tumors have proven highly valuable in fundamental oncology research and anticancer drug discovery. Both models inherently comprise advantages and caveats that have to be accounted for. Recently, we have enabled reliable in vitro culture techniques from lung cancer biopsies as Patients Lung Derived Tumoroids (PLDTs). This breakthrough provides the possibility of high-throughput drug screening covering the spectrum of lung cancer phenotypes seen clinically. We have adapted and optimized our in vitro three-dimensional model as a preclinical lung cancer model to recapitulate the tumor microenvironment (TME) using matrix reconstitution. Hence, we developed directly PLDTs to screen for chemotherapeutics and radiation treatment. This original model will enable precision medicine to become a reality, allowing a given patient sample to be screened for effective ex vivo therapeutics, aiming at tailoring of treatments specific to that individual. Hence, this tool can enhance clinical outcomes and avoid morbidity due to ineffective therapies.

Human tumor-associated monocytes/macrophages and their regulation of T cell responses in early-stage lung cancer

Data from mouse tumor models suggest that tumor-associated monocyte/macrophage lineage cells (MMLCs) dampen antitumor immune responses. However, given the fundamental differences between mice and humans in tumor evolution, genetic heterogeneity, and immunity, the function of MMLCs might be different in human tumors, especially during early stages of disease. Here, we studied MMLCs in early-stage human lung tumors and found that they consist of a mixture of classical tissue monocytes and tumor-associated macrophages (TAMs). The TAMs coexpressed M1/M2 markers, as well as T cell coinhibitory and costimulatory receptors. Functionally, TAMs did not primarily suppress tumor-specific effector T cell responses, whereas tumor monocytes tended to be more T cell inhibitory. TAMs expressing relevant MHC class I/tumor peptide complexes were able to activate cognate effector T cells. Mechanistically, programmed death-ligand 1 (PD-L1) expressed on bystander TAMs, as opposed to PD-L1 expressed on tumor cells, did not inhibit interactions between tumor-specific T cells and tumor targets. TAM-derived PD-L1 exerted a regulatory role only during the interaction of TAMs presenting relevant peptides with cognate effector T cells and thus may limit excessive activation of T cells and protect TAMs from killing by these T cells. These results suggest that the function of TAMs as primarily immunosuppressive cells might not fully apply to early-stage human lung cancer and might explain why some patients with strong PD-L1 positivity fail to respond to PD-L1 therapy.

Optimal identification of human conventional and nonconventional (CRTH2-IL7Rα-) ILC2s using additional surface markers

BACKGROUND

Human type 2 innate lymphoid cells (ILC2s) are identified by coupled detection of CRTH2 and IL7Rα on lineage negative (Lin^-) cells. Type 2 cytokine production by CRTH2^-IL7Rα^- innate lymphoid cells (ILCs) is unknown.

OBJECTIVE

We sought to identify CRTH2^-IL7Rα^- type 2 cytokine-producing ILCs and their disease relevance.

METHODS

We studied human blood and lung ILCs from asthmatic and control subjects by flow cytometry, ELISA, RNA sequencing, quantitative PCR, adoptive transfer to mice, and measurement of airway hyperreactivity by Flexivent.

RESULTS

We found that IL-5 and IL-13 were expressed not only by CRTH2⁺ but also by CRTH2^-IL7Rα⁺ and CRTH2^-IL7Rα^- (double-negative [DN]) human blood and lung cells. All 3 ILC populations expressed type 2 genes and induced airway hyperreactivity when adoptively transferred to mice. The frequency of type 2 cytokine-positive IL7Rα and DN ILCs were similar to that of CRTH2 ILCs in the blood and lung. Their frequency was higher in asthmatic patients than in disease controls. Transcriptomic analysis of CRTH2, IL7Rα, and DN ILCs confirmed the expression of mRNA for type 2 transcription factors in all 3 populations. Unexpectedly, the mRNA for GATA3 and IL-5 correlated better with mRNA for CD30, TNFR2, ICOS, CCR4, and CD200R1 than for CRTH2. By using a combination of these surface markers, especially CD30/TNFR2, we identified a previously unrecognized ILC2 population.

CONCLUSIONS

The commonly used surface markers for human ILC2s leave a majority of type 2 cytokine-producing ILC2s unaccounted for. We identified top GATA3-correlated cell surface-expressed genes in human ILCs by RNA sequencing. These new surface markers, such as CD30 and TNFR2, identified a previously unrecognized human ILC2 population. This ILC2 population is likely to contribute to asthma.

Cytokine profiling of tumor-infiltrating T lymphocytes by flow cytometry

Intracellular cytokine staining (ICS) utilizing fluorescently labeled, cytokine-specific antibodies is a powerful technique utilized to evaluate cytokine expression that provides resolution at the single cell level. Combined with multi-parameter flow cytometry, ICS can provide detailed information on complex cytokine profiles and cellular phenotypes within the tumor microenvironment, particularly for the CD4⁺ T helper and CD8⁺ cytotoxic T cell compartments. This technique provides critical information concerning tumor-infiltrating T cell function that is essential for evaluating existing or therapeutically-induced tumor antigen-specific T cell responses in both preclinical models and cancer patients. In this chapter we will discuss in detail the critical steps necessary for a successful ICS assay and outline common protocols for the evaluation of cytokine production from T cell subsets present within the tumor microenvironment.

Ectonucleotidase CD39 and Checkpoint Signalling Receptor Programmed Death 1 are Highly Elevated in Intratumoral Immune Cells in Non-small-cell Lung Cancer

Lung cancer is the leading cause of cancer death in both sexes worldwide and has a predicted 5-year survival rate of <20%. Immunotherapy targeting immune checkpoints such as the programmed death 1 (PD-1) signaling pathway has led to a shift of paradigm in the treatment of advanced non-small-cell lung cancer (NSCLC) but remains without effect in ∼80% of patients. Accumulating evidence suggests that several immunosuppressive mechanisms may work together in NSCLC. The contribution and cooperation between different immunosuppressive mechanisms in NSCLC remain unknown. Recently, the CD39-adenosine pathway has gained increasing attention as a crucial immunosuppressive mechanism and possible target for immunotherapy. Immune cells were extracted from lung and tumor tissue after lung resection in 12 patients by combined enzymatic and mechanical tissue disaggregation. A multiparameter flow cytometry panel was established to investigate the expression and coexpression of CD39 and PD-1 on key lymphocyte subtypes. Frequencies of CD39+, PD-1+, and CD39+/PD-1+cells were higher among both CD4+ and CD8+ T cells isolated from NSCLC tumor tissue than in T cells from normal lung tissue. Similarly, the frequency of FoxP3+ CD4+ T cells (Tregs) was highly significantly elevated in tumor tissue compared to adjacent lung tissue. The consistent upregulation of CD39 on immune cells in tumor microenvironment indicates that the CD39 signaling pathway may, in addition to the PD-1 pathway, represent another important mechanism for tumor-induced immunosuppression in NSCLC. In addition, the present study indicates that a comprehensive immune response profiling with flow cytometry may be both feasible and clinically relevant.

An Optimized Method to Isolate Human Fibroblasts from Tissue for ex vivo Analysis

Despite their involvement in many physiological and pathological processes, fibroblasts remain a poorly-characterized cell type. Analysis of primary fibroblasts while maintaining their in vivo phenotype is challenging: standard methods for fibroblast isolation require cell culture in vitro, which is known to alter phenotypes. Previously-described protocols for the dissociation of primary tissues fail to extract sufficient numbers of fibroblasts, instead largely yielding immune cells. Here, we describe an optimized method for generating a fibroblast-enriched single-cell suspension from human tissues using combined mechanical and enzymatic dissociation. This allows analysis of ex vivo fibroblasts without the need for culture in vitro.

Phenotypic and functional analysis of malignant mesothelioma tumor-infiltrating lymphocytes

Given the growing interest and promising preliminary results of immunotherapy in malignant pleural mesothelioma (MPM), it has become important to more fully understand the immune landscape in this tumor. This may be especially relevant in deciding who might benefit most from checkpoint blockade or agonist antibody therapy. Since the phenotype of tumor infiltrating lymphocytes (TILs) in MPM has not been fully described and their function has not been carefully assessed, we collected fresh tumor and blood from 22 patients undergoing surgical resection and analysed single cell suspensions by flow cytometry. The functionality of TILs was assessed by measurement of cytokine expression (IFN-γ) following overnight stimulation ex vivo. Results showed low numbers of CD8+ TILs whose function was either moderately or severely suppressed. The degree of TIL hypofunction did not correlate with the presence of co-existing macrophages or neutrophils, nor with expression of the inhibitory receptors PD-1, CD39 and CTLA-4. Hypofunction was associated with higher numbers of CD4 regulatory T cells (Tregs) and with expression of the inhibitory receptor TIGIT. On the other hand, presence of tissue-resident memory (Trm) cells and expression of TIM-3 on CD8+ cells were positively associated with cytokine production. However, Trm function was partially suppressed when the transcription factor Eomesodermin (Eomes) was co-expressed. Understanding the function of TILs in malignant mesothelioma may have clinical implications for immunotherapy, especially in choosing the best immunotherapy targets. Our data suggests that Treg cell blocking agents or TIGIT inhibitor antibodies might be especially valuable in these patients.

An optimised tissue disaggregation and data processing pipeline for characterising fibroblast phenotypes using single-cell RNA sequencing

Single-cell RNA sequencing (scRNA-Seq) provides a valuable platform for characterising multicellular ecosystems. Fibroblasts are a heterogeneous cell type involved in many physiological and pathological processes, but remain poorly-characterised. Analysis of fibroblasts is challenging: these cells are difficult to isolate from tissues, and are therefore commonly under-represented in scRNA-seq datasets. Here, we describe an optimised approach for fibroblast isolation from human lung tissues. We demonstrate the potential for this procedure in characterising stromal cell phenotypes using scRNA-Seq, analyse the effect of tissue disaggregation on gene expression, and optimise data processing to improve clustering quality. We also assess the impact of in vitro culture conditions on stromal cell gene expression and proliferation, showing that altering these conditions can skew phenotypes.

Function of Human Tumor-Infiltrating Lymphocytes in Early-Stage Non-Small Cell Lung Cancer

Cancer progression is marked by dysfunctional tumor-infiltrating lymphocytes (TIL) with high inhibitory receptor (IR) expression. Because IR blockade has led to clinical responses in some patients with non-small cell lung cancer (NSCLC), we investigated how IRs influenced CD8+ TIL function from freshly digested early-stage NSCLC tissues using a killing assay and intracellular cytokine staining after in vitro T-cell restimulation. Early-stage lung cancer TIL function was heterogeneous with only about one third of patients showing decrements in cytokine production and lytic function. TIL hypofunction did not correlate with clinical factors, coexisting immune cells (macrophages, neutrophils, or CD4+ T regulatory cells), nor with PD-1, TIGIT, TIM-3, CD39, or CTLA-4 expression. Instead, we found that the presence of the integrin αeβ7 (CD103), characteristic of tissue-resident memory cells (TRM), was positively associated with cytokine production, whereas expression of the transcription factor Eomesodermin (Eomes) was negatively associated with TIL function. These data suggest that the functionality of CD8+ TILs from early-stage NSCLCs may be influenced by competition between an antitumor CD103+ TRM program and an exhaustion program marked by Eomes expression. Understanding the mechanisms of T-cell function in the progression of lung cancer may have clinical implications for immunotherapy.

Deciphering myeloid-derived suppressor cells: isolation and markers in humans, mice and non-human primates

In cancer, infection and inflammation, the immune system's function can be dysregulated. Instead of fighting disease, immune cells may increase pathology and suppress host-protective immune responses. Myeloid cells show high plasticity and adapt to changing conditions and pathological challenges. Despite their relevance in disease pathophysiology, the identity, heterogeneity and biology of myeloid cells is still poorly understood. We will focus on phenotypical and functional markers of one of the key myeloid regulatory subtypes, the myeloid derived suppressor cells (MDSC), in humans, mice and non-human primates. Technical issues regarding the isolation of the cells from tissues and blood, timing and sample handling of MDSC will be detailed. Localization of MDSC in a tissue context is of crucial importance and immunohistochemistry approaches for this purpose are discussed. A minimal antibody panel for MDSC research is provided as part of the Mye-EUNITER COST action. Strategies for the identification of additional markers applying state of the art technologies such as mass cytometry will be highlighted. Such marker sets can be used to study MDSC phenotypes across tissues, diseases as well as species and will be crucial to accelerate MDSC research in health and disease.

Immune Checkpoint Ligand PD-L1 Is Upregulated in Pulmonary Lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis (LAM) is a slow-progressing metastatic disease that is driven by mutations in the tumor suppressor tuberous sclerosis complex 1/2 (TSC1/2). Rapamycin inhibits LAM cell proliferation and is the only approved treatment, but it cannot cause the regression of existing lesions and can only stabilize the disease. However, in other cancers, immunotherapies such as checkpoint blockade against PD-1 and its ligand PD-L1 have shown promise in causing tumor regression and even curing some patients. Thus, we asked whether PD-L1 has a role in LAM progression. In vitro, PD-L1 expression in murine Tsc2-null cells is unaffected by mTOR inhibition with torin but can be upregulated by IFN-γ. Using immunohistochemistry and single-cell flow cytometry, we found increased PD-L1 expression both in human lung tissue from patients with LAM and in Tsc2-null lesions in a murine model of LAM. In this model, PD-L1 is highly expressed in the lung by antigen-presenting and stromal cells, and activated T cells expressing PD-1 infiltrate the affected lung. In vivo treatment with anti-PD-1 antibody significantly prolongs mouse survival in the model of LAM. Together, these data demonstrate that PD-1/PD-L1-mediated immunosuppression may occur in LAM, and suggest new opportunities for therapeutic targeting that may provide benefits beyond those of rapamycin.

Robust method for isolation of tumor infiltrating lymphocytes with a high vital cell yield from small samples of renal cell carcinomas by a new collagenase-free mechanical procedure

BACKGROUND

Tumor-infiltrating lymphocytes (TIL) play an important role in the pathogenesis of renal cell carcinoma. Characterization of TIL requires efficient isolation procedures, especially in early stage disease when the tumor is of small in size. Conventional methods for isolating TIL are based on enzymatic tissue digestion, most frequently with collagenase. Collagenase isolation is limited by poor cell recovery, altered expression of cell-surface molecules, and impaired TIL-functionality. To overcome these limitations, we developed and optimized conditions for a robust collagenase-free mechanical procedure for improved isolation of TIL from renal cell carcinoma samples.

METHODS

TIL from tumor samples and T cells from peripheral blood were collected from 12 patients undergoing partial or radical nephrectomy. Samples were subjected to an enzymatic reference protocol and to a newly established mechanical isolation protocol. After viability staining, TIL-subpopulations were quantified and phenotyped by immunohistochemistry and flow-cytometric analysis, and were compared to characteristics of peripheral blood T cells. As a marker for TIL-functionality, T-cell cytokine induction was quantified after polyclonal stimulation.

RESULTS

We show that this new technique is rapid and allows identification of CD4 and CD8 T-cell subpopulations including CD4, CD8, and regulatory T cells expressing anergy markers such as programmed death-1 (PD-1) or B- and T-lymphocyte attenuator. When compared to the reference protocol involving collagenase digestion, the yield of TIL after mechanical isolation was higher and the expression of cell-surface markers was better preserved. Moreover, although antitumor activity was not assessed, mechanically isolated TIL are at least equally functional as T cells from peripheral blood, as polyclonal stimulation induced cytokines such as interferon-γ and tumor necrosis factor-α in both TIL and T cells from peripheral blood.

CONCLUSION

The mechanical procedure may be applied as a robust and rapid alternative to collagenase digestion for isolation of high amounts of phenotypically and functionally intact TIL from fresh tumor samples.

Dissociation, cellular isolation, and initial molecular characterization of neonatal and pediatric human lung tissues

Human lung morphogenesis begins by embryonic life and continues after birth into early childhood to form a complex organ with numerous morphologically and functionally distinct cell types. Pulmonary organogenesis involves dynamic changes in cell proliferation, differentiation, and migration of specialized cells derived from diverse embryonic lineages. Studying the molecular and cellular processes underlying formation of the fully functional lung requires isolating distinct pulmonary cell populations during development. We now report novel methods to isolate four major pulmonary cell populations from pediatric human lung simultaneously. Cells were dissociated by protease digestion of neonatal and pediatric lung and isolated on the basis of unique cell membrane protein expression patterns. Epithelial, endothelial, nonendothelial mesenchymal, and immune cells were enriched by fluorescence-activated cell sorting. Dead cells and erythrocytes were excluded by 7-aminoactinomycin D uptake and glycophorin-A (CD235a) expression, respectively. Leukocytes were identified by membrane CD45 (protein tyrosine phosphatase, receptor type C), endothelial cells by platelet endothelial cell adhesion molecule-1 (CD31) and vascular endothelial cadherin (CD144), and both were isolated. Thereafter, epithelial cell adhesion molecule (CD326)-expressing cells were isolated from the endothelial- and immune cell-depleted population to enrich epithelial cells. Cells lacking these membrane markers were collected as "nonendothelial mesenchymal" cells. Quantitative RT-PCR and RNA sequencing analyses of population specific transcriptomes demonstrate the purity of the subpopulations of isolated cells. The method efficiently isolates major human lung cell populations that we announce are now available through the National Heart, Lung, and Blood Institute Lung Molecular Atlas Program (LungMAP) for their further study.

Intra-tumoral delivery of CXCL11 via a vaccinia virus, but not by modified T cells, enhances the efficacy of adoptive T cell therapy and vaccines

T cell trafficking into tumors depends on a "match" between chemokine receptors on effector cells (e.g., CXCR3 and CCR5) and tumor-secreted chemokines. There is often a chemokine/chemokine receptor "mismatch", with tumors producing minute amounts of chemokines, resulting in inefficient targeting of effectors to tumors. We aimed to alter tumors to produce higher levels of CXCL11, a CXCR3 ligand, to attract more effector cells following immunotherapy. Mice bearing established subcutaneous tumors were studied. In our first approach, we used modified chimeric antigen receptor (CAR)-transduced human T cells to deliver CXCL11 (CAR/CXCL11) into tumors. In our second approach, we intravenously (iv) administered a modified oncolytic vaccinia virus (VV) engineered to produce CXCL11 (VV.CXCL11). The effect of these treatments on T cell trafficking into the tumors and anti-tumor efficacy after subsequent CAR T cell injections or anti-tumor vaccines was determined. CAR/CXCL11 and VV.CXCL11 significantly increased CXCL11 protein levels within tumors. For CAR/CXCL11, injection of a subsequent dose of CAR T cells did not result in increased intra-tumoral trafficking, and appeared to decrease the function of the injected CAR T cells. In contrast, VV.CXCL11 increased the number of total and antigen-specific T cells within tumors after CAR T cell injection or vaccination and significantly enhanced anti-tumor efficacy. Both approaches were successful in increasing CXCL11 levels within the tumors; however, only the vaccinia approach was successful in recruiting T cells and augmenting anti-tumor efficacy. VV.CXCL11 should be considered as a potential approach to augment adoptive T cell transfer or vaccine immunotherapy.

Quantitation of IRF3 Nuclear Translocation in Heterogeneous Cellular Populations from Cervical Tissue Using Imaging Flow Cytometry

Imaging flow cytometry (IFC) has become a powerful tool for studying the activation of transcriptional factors in heterogeneous cell populations in high-content imaging mode. With considerable interest to the clinical development of IFC, the question becomes how we can accelerate its application to solid tissues. We developed the first IFC-based procedure to quantify the nuclear translocation of interferon regulatory factor (IRF) 3, an important measure of induction of type I interferon antiviral response, in primary human immune cells including in solid tissues. After tissue digestion and protocol optimization by spectral flow cytometry, cell suspension is stained for intracellular IRF3 and acquired by IFC. Image analysis is performed using an optimized nuclear mask and similarity score parameter to correlate the location of IRF3 staining and a nuclear dye. The technique measures IRF3 activation at a single cell level and can detect small changes in the percent of activated cells providing objective quantitative data for statistical analysis.

Development of a Curative Therapeutic Vaccine (TheraVac) for the Treatment of Large Established Tumors

Harnessing immune system to treat cancer requires simultaneous generation of tumor-specific CTLs and curtailment of tumor immunosuppressive environment. Here, we developed an immunotherapeutic regimen capable of eliminating large established mouse tumors using HMGN1, a DC-activating TLR4 agonist capable of inducing anti-tumor immunity. Intratumoral delivery of HMGN1 with low dose of Cytoxan cured mice bearing small (∅ ≈ 0.5 cm), but not large (∅ ≈ 1.0 cm) CT26 tumors. Screening for activators capable of synergizing with HMGN1 in activating DC identified R848. Intratumoral delivery of HMGN1 and R848 plus Cytoxan eradicated large established CT26 tumors. The resultant tumor-free mice were resistant to subsequent challenge with CT26, indicating the generation of CT26-specific protective immunity. This immunotherapeutic regimen caused homing of tumor-infiltrating DC to draining lymph nodes and increased infiltration of T cells into tumor tissues. Cytoxan in this regimen could be replaced by anti-CTLA4) or anti-PD-L1. Importantly, this immunotherapeutic regimen was also curative for large established mouse Renca and EG7 tumors. Thus, we have developed a curative therapeutic vaccination regimen dubbed ‘TheraVac’ consisting of HMGN1 and R848 plus a checkpoint inhibitor, that can, without using exogenous tumor-associated antigen(s), eliminate various large tumors and induce tumor-specific immunity.

Human lung tumor FOXP3+ Tregs upregulate four "Treg-locking" transcription factors

Experimental data indicate that FOXP3+ Tregs can markedly curtail host antitumor immune responses, but the properties of human intratumoral Tregs are still largely unknown, in part due to significant methodologic problems. We studied the phenotypic, functional, epigenetic, and transcriptional features of Tregs in 92 patients with non-small-cell lung cancer, comparing the features of Tregs within tumors versus corresponding blood, lung, and lymph node samples. Intratumoral Treg numbers and suppressive function were significantly increased compared with all other sites but did not display a distinctive phenotype by flow cytometry. However, by undertaking simultaneous evaluation of mRNA and protein expression at the single-cell level, we demonstrated that tumor Tregs have a phenotype characterized by upregulated expression of FOXP3 mRNA and protein as well as significantly increased expression of EOS, IRF4, SATB1, and GATA1 transcription factor mRNAs. Expression of these "Treg-locking" transcription factors was positively correlated with levels of FOXP3 mRNA, with highest correlations for EOS and SATB1. EOS had an additional, FOXP3 mRNA-independent, positive correlation with FOXP3 protein in tumor Tregs. Our study identifies distinctive features of intratumoral Tregs and suggests that targeting Treg-locking transcription factors, especially EOS, may be of clinical importance for antitumor Treg-based therapy.

Therapeutic vaccine to cure large mouse hepatocellular carcinomas

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with limited therapeutic options. Here we report the development of a therapeutic vaccination regimen (shortened as ‘TheraVac’) consisting of intratumoral delivery of high-mobility group nucleosome-binding protein 1 (HMGN1), R848/resiquimod, and one of the checkpoint inhibitors (e.g. anti-CTLA4, anti-PD-L1, or low dose of Cytoxan). C57BL/6 mice harboring large (approximately 1 cm in diameter) established subcutaneous Hepa1-6 hepatomas were cured by intratumoral injections of TheraVac and became tumor-free long-term survivors. Importantly, the resultant tumor-free mice were resistant to re-challenge with Hepa1-6 hepatoma, not B16 melanoma, demonstrating the acquisition of hepatoma-specific immunity in the absence of any administered tumor antigen. Mechanistic studies showed that upon treatment with TheraVac, Hepa1-6-bearing mice generated increased Hepa1-6-specific CTLs in the draining lymph nodes and showed greatly upregulated expression of CXCL9, CXCL10, and IFN-γ and elevated infiltration of T lymphocytes in tumor tissues. Treatment of large Hepa1-6 hepatomas on one mouse flank also eliminated smaller (approximately 0.5 cm in diameter) hepatomas implanted on the other flank. Thus, TheraVac has potential as a curative immunotherapeutic regimen for the treatment of human HCC.

Intravesical BCG Induces CD4+ T-Cell Expansion in an Immune Competent Model of Bladder Cancer

Intravesical bacillus Calmette-Guérin (BCG) immunotherapy is the standard of care in treating non-muscle-invasive bladder cancer, yet its mechanism of action remains elusive. Both innate and adaptive immune responses have been implicated in BCG activity. Although prior research has indirectly demonstrated the importance of T cells and shown a rise in CD4⁺ T cells in bladder tissue after BCG, T-cell subpopulations have not been fully characterized. We investigated the relationship between effector and regulatory T cells in an immune competent, clinically relevant rodent model of bladder cancer. Our data demonstrate that cancer progression in the N-methyl-N-nitrosourea (MNU) rat model of bladder cancer was characterized by a decline in the CD8/FoxP3 ratio, consistent with decreased adaptive immunity. In contrast, treatment with intravesical BCG led to a large, transient rise in the CD4⁺ T-cell population in the urothelium and was both more effective and immunogenic compared with intravesical chemotherapy. Whole-transcriptome expression profiling of posttreatment intravesical CD4⁺ and CD8⁺ T cells revealed minimal differences in gene expression after BCG treatment. Together, our results suggest that although BCG induces T-cell recruitment to the bladder, the T-cell phenotype does not markedly change, implying that combining T-cell-activating agents with BCG might improve clinical activity. Cancer Immunol Res; 5(7); 594-603. ©2017 AACR.

Phenotype and function of tumor-associated neutrophils and their subsets in early-stage human lung cancer

Neutrophils accumulate in many types of human and murine tumors and represent a significant portion of tumor-infiltrating myeloid cells. Our current understanding of the role of neutrophils in tumor development has depended primarily on murine models of cancer. However, there are crucial species differences in the evolution of tumors, genetic diversity, immune and inflammatory responses, and intrinsic biology of neutrophils that might have a profound impact on the tumor development and function of neutrophils in mouse versus human tumors. To date, the majority of experimental approaches to study neutrophils in cancer patients have been limited to the examination of circulating blood neutrophils. The phenotype and function of tumor-associated neutrophils (TANs) in humans, particularly in the early stages of tumor development, have not been extensively investigated. Thus, the long-term goal of our work has been to characterize human TANs and determine their specific role in tumor development. Here, we summarize our findings on human TANs obtained from human early stage lung cancer patients. We will describe the phenotypes of different TAN subsets identified in early stage lung tumors, as well as their functional dialog with T cells.

The protumorigenic potential of FTY720 by promoting extramedullary hematopoiesis and MDSC accumulation

FTY720 (also called fingolimod) is recognized as an immunosuppressant and has been approved by the Food and Drug Administration to treat refractory multiple sclerosis. However, long-term administration of FTY720 potentially increases the risk for cancer in recipients. The underlying mechanisms remain poorly understood. Herein, we provided evidence that FTY720 administration potentiated tumor growth. Mechanistically, FTY720 enhanced extramedullary hematopoiesis and massive accumulation of myeloid-derived suppressor cells (MDSCs), which actively suppressed antitumor immune responses. Granulocyte-macrophage colony-stimulating factor (GM-CSF), mainly produced by MDSCs, was identified as a key factor to mediate these effects of FTY720 in tumor microenvironment. Furthermore, we showed that FTY720 triggers MDSCs to release GM-CSF via S1P receptor 3 (S1pr3) through Rho kinase and extracellular signal-regulated kinase-dependent pathway. Thus, our findings provide mechanistic explanation for the protumorigenic potentials of FTY720 and suggest that targeting S1pr3 simultaneously may be beneficial for the patients receiving FTY720 treatment.

Mouse versus Human Neutrophils in Cancer: A Major Knowledge Gap

Many types of cancer recruit neutrophils that could have protumor or antitumor effects on tumor development. Numerous findings in murine models suggest a predominantly protumoral role for neutrophils in cancer development. However, there are fundamental differences between mouse and human tumors in the evolution of tumors, genetic diversity, immune response, and also in the intrinsic biology of neutrophils that might have a profound impact on tumor development and the function of these cells. A crucial difference is that the majority of mouse tumor models lack the prolonged initial phases of multistage tumor evolution present in humans when antitumoral mechanisms are activated. In this review, we discuss the challenges specific to cross-species extrapolation of neutrophil function during mouse versus human tumor development.

Origin and Role of a Subset of Tumor-Associated Neutrophils with Antigen-Presenting Cell Features in Early-Stage Human Lung Cancer

Based on studies in mouse tumor models, granulocytes appear to play a tumor-promoting role. However, there are limited data about the phenotype and function of tumor-associated neutrophils (TANs) in humans. Here, we identify a subset of TANs that exhibited characteristics of both neutrophils and antigen-presenting cells (APCs) in early-stage human lung cancer. These APC-like "hybrid neutrophils," which originate from CD11b(+)CD15(hi)CD10(-)CD16(low) immature progenitors, are able to cross-present antigens, as well as trigger and augment anti-tumor T cell responses. Interferon-γ and granulocyte-macrophage colony-stimulating factor are requisite factors in the tumor that, working through the Ikaros transcription factor, synergistically exert their APC-promoting effects on the progenitors. Overall, these data demonstrate the existence of a specialized TAN subset with anti-tumor capabilities in human cancer.

The Nature of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment

Myeloid-derived suppressor cells (MDSC) are one of the major components of the tumor microenvironment. The main feature of these cells is their potent immune suppressive activity. MDSC are generated in the bone marrow and, in tumor-bearing hosts, migrate to peripheral lymphoid organs and the tumor to contribute to the formation of the tumor microenvironment. Recent findings have revealed differences in the function and fate of MDSC in the tumor and peripheral lymphoid organs. We review these findings here and, in this context, we discuss the current understanding as to the nature of these differences, the underlying mechanisms, and their potential impact on the regulation of tumor progression.