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BACKGROUND AND AIMS Hypoxia is one of the central players in shaping the immune context of the tumor microenvironment (TME). However,the complex interplay between immune cell infiltrates within the hypoxic TME of HCC remains to be elucidated. APPROACH AND RESULTS We analyzed the immune landscapes of hypoxia-low and hypoxia-high tumor regions using cytometry by time of light,immunohistochemistry,and transcriptomic analyses. The mechanisms of immunosuppression in immune subsets of interest were further explored using in vitro hypoxia assays. Regulatory T cells (Tregs) and a number of immunosuppressive myeloid subsets,including M2 macrophages and human leukocyte antigen-DR isotype (HLA-DRlo ) type 2 conventional dendritic cell (cDC2),were found to be significantly enriched in hypoxia-high tumor regions. On the other hand,the abundance of active granzyme Bhi PD-1lo CD8+ T cells in hypoxia-low tumor regions implied a relatively active immune landscape compared with hypoxia-high regions. The up-regulation of cancer-associated genes in the tumor tissues and immunosuppressive genes in the tumor-infiltrating leukocytes supported a highly pro-tumorigenic network in hypoxic HCC. Chemokine genes such as CCL20 (C-C motif chemokine ligand 20) and CXCL5 (C-X-C motif chemokine ligand 5) were associated with recruitment of both Tregs and HLA-DRlo cDC2 to hypoxia-high microenvironments. The interaction between Tregs and cDC2 under a hypoxic TME resulted in a loss of antigen-presenting HLA-DR on cDC2. CONCLUSIONS We uncovered the unique immunosuppressive landscapes and identified key immune subsets enriched in hypoxic HCC. In particular,we identified a potential Treg-mediated immunosuppression through interaction with a cDC2 subset in HCC that could be exploited for immunotherapies. View Publication

Immunosuppressive factors in the tumor microenvironment (TME) impair T cell function and limit the antitumor immune response. T cell surface receptors and surface proteins that influence interactions and function in the TME are proven targets for cancer immunotherapy. However,how the entire surface proteome remodels in primary human T cells in response to specific suppressive factors in the TME remains to be broadly and systematically characterized. Here,using a reductionist cell culture approach with primary human T cells and stable isotopic labeling with amino acids in cell culture-based quantitative cell surface capture glycoproteomics,we examined how two immunosuppressive TME factors,regulatory T cells (Tregs) and hypoxia,globally affect the activated CD8+ surface proteome (surfaceome). Surprisingly,coculturing primary CD8+ T cells with Tregs only modestly affected the CD8+ surfaceome but did partially reverse activation-induced surfaceomic changes. In contrast,hypoxia drastically altered the CD8+ surfaceome in a manner consistent with both metabolic reprogramming and induction of an immunosuppressed state. The CD4+ T cell surfaceome similarly responded to hypoxia,revealing a common hypoxia-induced surface receptor program. Our surfaceomics findings suggest that hypoxic environments create a challenge for T cell activation. These studies provide global insight into how Tregs and hypoxia remodel the T cell surfaceome and we believe represent a valuable resource to inform future therapeutic efforts to enhance T cell function. View Publication

As a potential source of myofibroblasts,pericytes may play a role in human peritoneal fibrosis. The culture of primary vascular pericytes in animals has previously been reported,most of which are derived from cerebral and retinal microvasculature. Here,in the field of peritoneal dialysis,we describe a method to isolate and characterize mouse peritoneal microvascular pericytes. The mesenteric tissues of five mice were collected and digested by type II collagenase and type I DNase. After cell attachment,the culture fluid was replaced with pericyte-conditioned medium. Pericytes with high purity (99.0%) could be isolated by enzymatic disaggregation combined with conditional culture and magnetic activated cell sorting. The primary cells were triangular or polygonal with protrusions,and confluent cell culture could be established in 3??days. The primary pericytes were positive for platelet-derived growth factor receptor-$\beta$,$\alpha$-smooth muscle actin,neuron-glial antigen 2,and CD13. Moreover,they promoted formation of endothelial tubes,and pericyte-myofibroblast transition occurred after treatment with transforming growth factor-$\beta$1. In summary,we describe here a reproducible isolation protocol for primary peritoneal pericytes,which may be a powerful tool for in??vitro peritoneal fibrosis studies. View Publication

Therapeutic IL-12 has demonstrated the ability to reduce local immune suppression in preclinical models,but clinical development has been limited by severe inflammation-related adverse events with systemic administration. Here,we show that potent immunologic tumor control of established syngeneic carcinomas can be achieved by i.t. administration of a tumor-targeted IL-12 antibody fusion protein (NHS-rmIL-12) using sufficiently low doses to avoid systemic toxicity. Single-cell transcriptomic analysis and ex vivo functional assays of NHS-rmIL-12-treated tumors revealed reinvigoration and enhanced proliferation of exhausted CD8+ T lymphocytes,induction of Th1 immunity,and a decrease in Treg number and suppressive capacity. Similarly,myeloid cells transitioned toward inflammatory phenotypes and displayed reduced suppressive capacity. Cell type-specific IL-12 receptor-KO BM chimera studies revealed that therapeutic modulation of both lymphoid and myeloid cells is required for maximum treatment effect and tumor cure. Study of single-cell data sets from human head and neck carcinomas revealed IL-12 receptor expression patterns similar to those observed in murine tumors. These results describing the diverse mechanisms underlying tumor-directed IL-12-induced antitumor immunity provide the preclinical rationale for the clinical study of i.t. NHS-IL-12. View Publication

BACKGROUND Radiotherapy enhances antitumor immunity. However,it also induces immunosuppressive responses,which are major hurdles for an effective treatment. Thus,targeting the immunosuppressive tumor microenvironment is essential for enhancing the antitumor immunity after radiotherapy. Retrospective studies show that a blockade of PI3K$\delta$ and/or $\gamma$,which are abundant in leukocytes,exhibits antitumor immune response by attenuating activity of immune suppressive cells,however,the single blockade of PI3K$\delta$ or $\gamma$ is not sufficient to completely eliminate solid tumor. METHODS We used BR101801,PI3K$\delta$/$\gamma$ inhibitor in the CT-26 syngeneic mouse model with a subcutaneously implanted tumor. BR101801 was administered daily,and the target tumor site was locally irradiated. We monitored the tumor growth regularly and evaluated the immunological changes using flow cytometry,ELISpot,and transcriptional analysis. RESULTS This study showed that BR101801 combined with irradiation promotes systemic antitumor immunity and abscopal response by attenuating the activity of immune suppressive cells in the CT-26 tumor model. BR101801 combined with irradiation systemically reduced the proliferation of regulatory T cells (Tregs) and enhanced the number of tumor-specific CD8$\alpha$+ T cells in the tumor microenvironment,thereby leading to tumor regression. Furthermore,the high ratio of CD8$\alpha$+ T cells to Tregs was maintained for 14 days after irradiation,resulting in remote tumor regression in metastatic lesions,the so-called abscopal effect. Moreover,our transcriptomic analysis showed that BR101801 combined with irradiation promoted the immune-stimulatory tumor microenvironment,suggesting that the combined therapy converts immunologically cold tumors into hot one. CONCLUSIONS Our data suggest the first evidence that PI3K$\delta$/$\gamma$ inhibition combined with irradiation promotes systemic antitumor immunity against solid tumors,providing the preclinical result of the potential use of PI3K$\delta$/$\gamma$ inhibitor as an immune-regulatory radiosensitizer. View Publication

Regulatory T cells (Tregs) are capable of inhibiting the proliferation,activation and function of T cells and play an important role in impeding the immune response to cancer. In chronic lymphocytic leukemia (CLL) a dysfunctional immune response and elevated percentage of effector-like phenotype Tregs have been described. In this study,using the Eµ-TCL1 mouse model of CLL,we evaluated the changes in the Tregs phenotype and their expansion at different stages of leukemia progression. Importantly,we show that Tregs depletion in DEREG mice triggered the expansion of new anti-leukemic cytotoxic T cell clones leading to leukemia eradication. In TCL1 leukemia-bearing mice we identified and characterized a specific Tregs subpopulation,the phenotype of which suggests its role in the formation of an immunosuppressive microenvironment,supportive for leukemia survival and proliferation. This observation was also confirmed by the gene expression profile analysis of these TCL1-specific Tregs. The obtained data on Tregs are consistent with those described so far,however,above all show that the changes in the Tregs phenotype described in CLL result from the formation of a specific,described in this study Tregs subpopulation. In addition,functional tests revealed the ability of Tregs to inhibit T cells that recognize model antigens expressed by leukemic cells. Moreover,inhibition of Tregs with a MALT1 inhibitor provided a therapeutic benefit,both as monotherapy and also when combined with an immune checkpoint inhibitor. Altogether,activation of Tregs appears to be crucial for CLL progression. View Publication

BACKGROUND Bispecific T-cell engager (BiTE) molecules induce redirected lysis of cancer cells by T cells and are an emerging modality for solid tumor immunotherapy. While signs of clinical activity have been demonstrated,efficacy of T-cell engagers (TCEs) in solid tumors settings,molecular determinants of response,and underlying mechanisms of resistance to BiTE therapy require more investigation. METHODS To uncover cancer cell-intrinsic genetic modifiers of TCE-mediated cytotoxicity,we performed genome-wide CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loss-of-function and CRISPRa (CRISPR activation) gain-of-function screens using TCEs against two distinct tumor-associated antigens (TAAs). By using in vitro T-cell cytotoxicity assays and in vivo efficacy studies,we validated the roles of two common pathways identified in our screen,T-cell costimulation pathway and apoptosis pathway,as key modifiers of BiTE activity. RESULTS Our genetic screens uncovered TAAs-independent cancer cell-intrinsic genes with functions in autophagy,T-cell costimulation,the apoptosis pathway,chromatin remodeling,and cytokine signaling that altered responsiveness to BiTE-mediated killing. Notably,loss of CD58 (the ligand of the CD2 T-cell costimulatory receptor),a gene frequently altered in cancer,led to decreased TCE-mediated cytotoxicity,T-cell activation and antitumor efficacy in vitro and in vivo. Moreover,the effects of CD58 loss were synergistically compounded by concurrent loss of CD80/CD86 (ligands for the CD28 T-cell costimulatory receptor),whereas joint CD2 and CD28 costimulation additively enhanced TCE-mediated killing,indicating non-redundant costimulatory mechanisms between the two pathways. Additionally,loss of CFLAR (Caspase-8 and FADD Like Apoptosis Regulator),BCL2L1,and BID (BH3 Interacting Domain Death Agonist) induced profound changes in sensitivity to TCEs,indicating that key regulators of apoptosis,which are frequently altered in cancer,impact tumor responsiveness to BiTE therapy. CONCLUSIONS This study demonstrates that genetic alterations central to carcinogenesis and commonly detected in cancer samples lead to significant modulation of BiTE antitumor activity in vitro and in vivo,findings with relevance for a better understanding of patient responses to BiTE therapy and novel combinations that enhance TCE efficacy. View Publication

BACKGROUND Myeloid-derived suppressor cells (MDSCs) represent a negative prognostic factor in malignant melanoma. These cells are generated under chronic inflammatory conditions typical of cancer. The transcription factor signal transducer and activator of transcription 3 (STAT3) orchestrates MDSC accumulation and acquisition of immunosuppressive properties. Here we studied STAT3 inhibition by Napabucasin as a way to block MDSC accumulation and activity and its potential to treat malignant melanoma. METHODS In vitro generated murine MDSC and primary MDSC from melanoma-bearing mice were used to investigate the effects of Napabucasin on MDSC in vitro. The RET transgenic mouse model of malignant melanoma was used to examine Napabucasin therapy efficiency and its underlying mechanisms in vivo. Furthermore,STAT3 activation and its correlation with survival were explored in MDSC from 19 patients with malignant melanoma and human in vitro generated monocytic myeloid-derived suppressor cell (M-MDSC) were used to evaluate the effects of Napabucasin. RESULTS Napabucasin was able to abrogate the capacity of murine MDSC to suppress CD8+ T-cell proliferation. The STAT3 inhibitor induced apoptosis in murine MDSC,significantly increased expression of molecules associated with antigen processing and presentation,as well as slightly decreased expression of immunosuppressive factors on these cells. RET transgenic mice treated with Napabucasin showed prolonged survival accompanied by a strong accumulation of tumor-infiltrating antigen-presenting cells and activation of CD8+ and CD4+ T cells. Interestingly,patients with malignant melanoma with high expression of activated STAT3 in circulating M-MDSC showed significantly worse progression-free survival (PFS) than patients with low levels of activated STAT3. In addition,Napabucasin was able to abrogate suppressive capacity of human in vitro generated M-MDSC. CONCLUSION Our findings demonstrate that STAT3 inhibitor Napabucasin completely abrogated the immunosuppressive capacity of murine MDSC and human M-MDSC and improved melanoma-bearing mouse survival. Moreover,patients with malignant melanoma with high expression levels of activated STAT3 in M-MDSC displayed shorter PFS,indicating its role as a promising therapeutic target in patients with malignant melanoma and a predictive marker for their clinical outcome. View Publication

BACKGROUND Epidemiological surveys have revealed that low serum vitamin D level was correlated with increased risk of tumors. Dysfunctional T cells in patients with tumor are characterized as exhausted with high levels of immune checkpoint receptors (ICRs). However,whether the reduced level of vitamin D in patients with cancer correlates with cytotoxic T-cell exhaustion is unknown. METHODS Periphery blood samples from 172 patients with non-small cell lung cancer (NSCLC) were prospectively collected. Patients with NSCLC received one course of intravenous docetaxel (75 mg/m2) followed by treatment with or without rocaltrol at a dose of 0.5-2.0 µg/day for total of 3 weeks. We performed phenotypical and functional analysis of T-cell through flow cytometry. Vitamin D receptor (VDR) knockout and overexpression CD8+ and V$\delta$2+ T cells were constructed using Cas9-gRNA targeted and overexpressing approaches to identify 1$\alpha$,25(OH)2D3/VDR-mediated transcription regulation for ICRs or antitumor activity in T cells. RESULTS We show that serum level of vitamin D is negatively correlated with expression of programmed cell death-1 (PD-1),T-cell immunoreceptor with Ig and ITIM domains (TIGIT),and T-cell immunoglobulin and mucin-domain containing-3 (Tim-3),but positively correlated with CD28 expression on CD8+ and V$\gamma$9V$\delta$2+ T cells in patients with NSCLC. 1$\alpha$,25(OH)2D3,the active form of vitamin D,promotes the nuclear translocation of VDR,which binds to the promoter region of Pdcd1,Tim3,and Tigit genes and inhibits their expression. Besides,1$\alpha$,25(OH)2D3 pretreatment also promotes the methylation of CpG island in the promoter region of the Pdcd1 gene and increases H3K27 acetylation at the promoter region of the Cd28 gene,which leads to surface PD-1 downregulation and CD28 upregulation,respectively. We further reveal that VDR-mediated Ca2+ influx enhanced expression of Th1 cytokines via T-cell receptor activation. Functionally,1$\alpha$,25(OH)2D3 pretreated CD8+ T cells or V$\gamma$9V$\delta$2+ T cells showed increased Th1 cytokine production and enhanced antitumor immunity. Finally,oral 1$\alpha$,25(OH)2D3 could also decrease expression of PD-1,Tim-3,TIGIT and increase expression of CD28,resulting in cytokine production (associated with antitumor immunity) by cytotoxic T cells of patients with NSCLC. CONCLUSIONS Our findings uncover the pleiotropic effects of 1$\alpha$,25(OH)2D3 in rescuing the exhausted phenotype of human cytotoxic T cells in patients with tumor and in promoting their antitumor immunity. TRIAL REGISTRATION NUMBER ChiCTR2100051135. View Publication

Chronic decreases in the second messenger cyclic AMP (cAMP) occur in numerous settings,but how cells compensate for such decreases is unknown. We have used a unique system-murine dendritic cells (DCs) with a DC-selective depletion of the heterotrimeric GTP binding protein G$\alpha$s-to address this issue. These mice spontaneously develop Th2-allergic asthma and their DCs have persistently lower cAMP levels. We found that phosphodiesterase 4B (PDE4B) is the primary phosphodiesterase expressed in DCs and that its expression is preferentially decreased in G$\alpha$s-depleted DCs. PDE4B expression is dynamic,falling and rising in a protein kinase A-dependent manner with decreased and increased cAMP concentrations,respectively. Treatment of DCs that drive enhanced Th2 immunity with a PDE4B inhibitor ameliorated DC-induced helper T cell response. We conclude that PDE4B is a homeostatic regulator of cellular cAMP concentrations in DCs and may be a target for treating Th2-allergic asthma and other settings with low cellular cAMP concentrations. View Publication

BACKGROUND The Regulatory T cell (Treg) lineage is defined by the transcription factor FOXP3,which controls immune-suppressive gene expression profiles. Tregs are often recruited in high frequencies to the tumor microenvironment where they can suppress antitumor immunity. We hypothesized that pharmacological inhibition of FOXP3 by systemically delivered,unformulated constrained ethyl-modified antisense oligonucleotides could modulate the activity of Tregs and augment antitumor immunity providing therapeutic benefit in cancer models and potentially in man. METHODS We have identified murine Foxp3 antisense oligonucleotides (ASOs) and clinical candidate human FOXP3 ASO AZD8701. Pharmacology and biological effects of FOXP3 inhibitors on Treg function and antitumor immunity were tested in cultured Tregs and mouse syngeneic tumor models. Experiments were controlled by vehicle and non-targeting control ASO groups as well as by use of multiple independent FOXP3 ASOs. Statistical significance of biological effects was evaluated by one or two-way analysis of variance with multiple comparisons. RESULTS AZD8701 demonstrated a dose-dependent knockdown of FOXP3 in primary Tregs,reduction of suppressive function and efficient target downregulation in humanized mice at clinically relevant doses. Surrogate murine FOXP3 ASO,which efficiently downregulated Foxp3 messenger RNA and protein levels in primary Tregs,reduced Treg suppressive function in immune suppression assays in vitro. FOXP3 ASO promoted more than 70% reduction in FOXP3 levels in Tregs in vitro and in vivo,strongly modulated Treg effector molecules (eg,ICOS,CTLA-4,CD25 and 4-1BB),and augmented CD8+ T cell activation and produced antitumor activity in syngeneic tumor models. The combination of FOXP3 ASOs with immune checkpoint blockade further enhanced antitumor efficacy. CONCLUSIONS Antisense inhibitors of FOXP3 offer a promising novel cancer immunotherapy approach. AZD8701 is being developed clinically as a first-in-class FOXP3 inhibitor for the treatment of cancer currently in Ph1a/b clinical trial (NCT04504669). View Publication

Alveolar macrophages (AMs) are functionally important innate cells involved in lung homeostasis and immunity and whose diversity in health and disease is a subject of intense investigations. Yet,it remains unclear to what extent conditions like smoking or chronic obstructive pulmonary disease (COPD) trigger changes in the AM compartment. Here,we aimed to explore heterogeneity of human AMs isolated from healthy nonsmokers,smokers without COPD,and smokers with COPD by analyzing BAL fluid cells by flow cytometry and bulk and single-cell RNA sequencing. We found that subpopulations of BAL fluid CD206+ macrophages could be distinguished based on their degree of autofluorescence in each subject analyzed. CD206+ autofluorescenthigh AMs were identified as classical,self-proliferative AM,whereas autofluorescentlow AMs were expressing both monocyte and classical AM-related genes,supportive of a monocytic origin. Of note,monocyte-derived autofluorescentlow AMs exhibited a functionally distinct immunoregulatory profile,including the ability to secrete the immunosuppressive cytokine IL-10. Interestingly,single-cell RNA-sequencing analyses showed that transcriptionally distinct clusters of classical and monocyte-derived AM were uniquely enriched in smokers with and without COPD as compared with healthy nonsmokers. Of note,such smoking-associated clusters exhibited gene signatures enriched in detoxification,oxidative stress,and proinflammatory responses. Our study independently confirms previous reports supporting that monocyte-derived macrophages coexist with classical AM in the airways of healthy subjects and patients with COPD and identifies smoking-associated changes in the AM compartment that may favor COPD initiation or progression. View Publication