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Advanced pancreatic ductal adenocarcinomas (PDACs) respond poorly to all therapies, including the first-line treatment, chemotherapy, the latest immunotherapies, and KRAS-targeting therapies. Despite an enormous effort to improve therapeutic efficacy in late-stage PDAC patients, effective treatment modalities remain an unmet medical challenge. To change the status quo, we explored the key signaling networks underlying the universally poor response of PDAC to therapy. Here, we report a previously unknown chemo-induced symbiotic signaling circuit that adaptively confers chemoresistance in patients and mice with advanced PDAC. By integrating single-cell transcriptomic data from PDAC mouse models and clinical pathological information from PDAC patients, we identified Yap1 in cancer cells and Cox2 in stromal fibroblasts as two key nodes in this signaling circuit. Co-targeting Yap1 in cancer cells and Cox2 in stroma sensitized PDAC to Gemcitabine treatment and dramatically prolonged survival of mice bearing late-stage PDAC, whereas simultaneously inhibiting Yap1 and Cox2 only in cancer cells was ineffective. Mechanistically, chemotherapy triggers non-canonical Yap1 activation by nemo-like kinase in 14-3-3ζ-overexpressing PDAC cells and increases secretion of CXCL2/5, which bind to CXCR2 on fibroblasts to induce Cox2 and PGE2 expression, which reciprocally facilitate PDAC cell survival. Finally, analyses of PDAC patient data revealed that patients who received Statins, which inhibit Yap1 signaling, and Cox2 inhibitors (including Aspirin) while receiving Gemcitabine displayed markedly prolonged survival compared to others. The robust anti-tumor efficacy of Statins and Aspirin, which co-target the chemo-induced adaptive circuit in the tumor cells and stroma, signifies a unique therapeutic strategy for PDAC. [ABSTRACT FROM AUTHOR]

Inflammasome activity is important for the immune response and is instrumental in numerous clinical conditions. Here we identify a mechanism that modulates the central Caspase-1 and NLR (Nod-like receptor) adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD). We show that the function of ASC in assembling the inflammasome is controlled by its modification with SUMO (small ubiquitin-like modifier) and identify that the nuclear ZBTB16 (zinc-finger and BTB domain-containing protein 16) promotes this SUMOylation. The physiological significance of this activity is demonstrated through the reduction of acute inflammatory pathogenesis caused by a constitutive hyperactive inflammasome by ablating ZBTB16 in a mouse model of Muckle-Wells syndrome. Together our findings identify an further mechanism by which ZBTB16-dependent control of ASC SUMOylation assembles the inflammasome to promote this pro-inflammatory response. Inflammasomes are multiprotein complexes, including the protein ASC, that assemble in response to inflammatory stimulation. Here the authors characterise the regulation of ASC during inflammasome formation and show the involvement of SUMOylation and zinc-finger and BTB domain-containing protein 16 (ZBTB16). [ABSTRACT FROM AUTHOR]

T-cell-based immune checkpoint blockade therapy (ICB) can be undermined by local immunosuppressive M2-like tumor-associated macrophages (TAMs). However, modulating macrophages has proved difficult as the molecular and functional features of M2-TAMs on tumor growth are still uncertain. Here we reported that immunosuppressive M2 macrophages render cancer cells resistant to CD8+ T-cell-dependent tumor-killing refractory ICB efficacy by secreting exosomes. Proteomics and functional studies revealed that M2 macrophage-derived exosome (M2-exo) transmitted apolipoprotein E (ApoE) to cancer cells conferring ICB resistance by downregulated MHC-I expression curbing tumor intrinsic immunogenicity. Mechanistically, M2 exosomal ApoE diminished the tumor-intrinsic ATPase activity of binding immunoglobulin protein (BiP) to decrease tumor MHC-I expression. Sensitizing ICB efficacy can be achieved by the administration of ApoE ligand, EZ-482, enhancing ATPase activity of BiP to boost tumor-intrinsic immunogenicity. Therefore, ApoE may serve as a predictor and a potential therapeutic target for ICB resistance in M2-TAMs-enriched cancer patients. Collectively, our findings signify that the exosome-mediated transfer of functional ApoE from M2 macrophages to the tumor cells confers ICB resistance. Our findings also provide a preclinical rationale for treating M2-enriched tumors with ApoE ligand, EZ-482, to restore sensitivity to ICB immunotherapy. [ABSTRACT FROM AUTHOR]

The gut microbiota have long been recognized to play a key role in human health and disease. Currently, several lines of evidence from preclinical to clinical research have gradually established that the gut microbiota can modulate antitumor immunity and affect the efficacy of cancer immunotherapies, especially immune checkpoint inhibitors (ICIs). Deciphering the underlying mechanisms reveals that the gut microbiota reprogram the immunity of the tumor microenvironment (TME) by engaging innate and/or adaptive immune cells. Notably, one of the primary modes by which the gut microbiota modulate antitumor immunity is by means of metabolites, which are small molecules that could spread from their initial location of the gut and impact local and systemic antitumor immune response to promote ICI efficiency. Mechanistic exploration provides novel insights for developing rational microbiota-based therapeutic strategies by manipulating gut microbiota, such as fecal microbiota transplantation (FMT), probiotics, engineered microbiomes, and specific microbial metabolites, to augment the efficacy of ICI and advance the age utilization of microbiota precision medicine. [ABSTRACT FROM AUTHOR]

Heterotypic interactions between tumor cells and macrophages can enable tumor progression and hold potential for the development of therapeutic interventions. However, the communication between tumors and macrophages and its mechanism are poorly understood. Here, we find that tumor‐associated macrophages (TAM) from tumor‐bearing mice have high amounts of lipid as compared to macrophages from tumor‐free mice. TAM also present high lipid content in clinical human gastric cancer patients. Functionally, TAM with high lipid levels are characterized by polarized M2‐like profiling, and exhibit decreased phagocytic potency and upregulated programmed death ligand 1 (PD‐L1) expression, blocking anti–tumor T cell responses to support their immunosuppressive function. Mechanistically, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identifies the specific PI3K pathway enriched within lipid‐laid TAM. Lipid accumulation in TAM is mainly caused by increased uptake of extracellular lipids from tumor cells, which leads to the upregulated expression of gamma isoform of phosphoinositide 3‐kinase (PI3K‐γ) polarizing TAM to M2‐like profiling. Correspondingly, a preclinical gastric cancer model is used to show pharmacological targeting of PI3K‐γ in high‐lipid TAM with a selective inhibitor, IPI549. IPI549 restores the functional activity of macrophages and substantially enhances the phagocytosis activity and promotes cytotoxic‐T‐cell‐mediated tumor regression. Collectively, this symbiotic tumor‐macrophage interplay provides a potential therapeutic target for gastric cancer patients through targeting PI3K‐γ in lipid‐laden TAM. [ABSTRACT FROM AUTHOR]

The immunosuppressive status of the tumor microenvironment (TME) remains poorly defined due to a lack of understanding regarding the function of tumor-associated macrophages (TAMs), which are abundant in the TME. TAMs are crucial drivers of tumor progression, metastasis, and resistance to therapy. Intra- and inter-tumoral spatial heterogeneities are potential keys to understanding the relationships between subpopulations of TAMs and their functions. Antitumor M1-like and pro-tumor M2-like TAMs coexist within tumors, and the opposing effects of these M1/M2 subpopulations on tumors directly impact current strategies to improve antitumor immune responses. Recent studies have found significant differences among monocytes or macrophages from distinct tumors, and other investigations have explored the existence of diverse TAM subsets at the molecular level. In this review, we discuss emerging evidence highlighting the redefinition of TAM subpopulations and functions in the TME and the possibility of separating macrophage subsets with distinct functions into antitumor M1-like and pro-tumor M2-like TAMs during the development of tumors. Such redefinition may relate to the differential cellular origin and monocyte and macrophage plasticity or heterogeneity of TAMs, which all potentially impact macrophage biomarkers and our understanding of how the phenotypes of TAMs are dictated by their ontogeny, activation status, and localization. Therefore, the detailed landscape of TAMs must be deciphered with the integration of new technologies, such as multiplexed immunohistochemistry (mIHC), mass cytometry by time-of-flight (CyTOF), single-cell RNA-seq (scRNA-seq), spatial transcriptomics, and systems biology approaches, for analyses of the TME. [ABSTRACT FROM AUTHOR]

Closing the door to neutrophils: Brain metastasis, which occurs in many cancers, is an ominous finding that remains difficult to treat. It is challenging to get treatments into these tumors, and their microenvironment is not as well studied as that of peripheral cancers. Zhang et al. found that an epigenetic modifying protein called enhancer of zeste homolog 2 (EZH2) is overexpressed in brain metastases, where it stimulates signaling pathways recruiting immunosuppressive neutrophils into the tumors. By examining the mechanism of action of EZH2 in this setting, the authors identified two approaches for blocking this influx of neutrophils and enhancing antitumor immune responses and then demonstrated their effectiveness in multiple mouse models. The functions of immune cells in brain metastases are unclear because the brain has traditionally been considered "immune privileged." However, we found that a subgroup of immunosuppressive neutrophils is recruited into the brain, enabling brain metastasis development. In brain metastatic cells, enhancer of zeste homolog 2 (EZH2) is highly expressed and phosphorylated at tyrosine-696 (pY696)–EZH2 by nuclear-localized Src tyrosine kinase. Phosphorylation of EZH2 at Y696 changes its binding preference from histone H3 to RNA polymerase II, which consequently switches EZH2's function from a methyltransferase to a transcription factor that increases c-JUN expression. c-Jun up-regulates protumorigenic inflammatory cytokines, including granulocyte colony-stimulating factor (G-CSF), which recruits Arg1+- and PD-L1+ immunosuppressive neutrophils into the brain to drive metastasis outgrowth. G-CSF–blocking antibodies or immune checkpoint blockade therapies combined with Src inhibitors impeded brain metastasis in multiple mouse models. These findings indicate that pY696-EZH2 can function as a methyltransferase-independent transcription factor to facilitate the brain infiltration of immunosuppressive neutrophils, which could be clinically targeted for brain metastasis treatment. [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade (ICB) immunotherapy increases antitumor immunity by blocking cytotoxic-T-lymphocyte-associated protein 4 (CTLA-4) or programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) and displays robust clinical responses in various cancers. However, ICB immunotherapy also triggers severe inflammatory side effects, known as immune-related adverse effects (irAEs). One of the most common toxicities is immune checkpoint blockade-associated colitis (ICB associated colitis). The exact mechanism of ICB associated colitis remains to be explored. Here, we combined ICB (anti–CTLA-4 and anti-PD-1) treatment with a standard colitis model, in which a more severe form of colitis is induced in mice, to recapitulate the clinical observations in patients receiving combined ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) therapy, during which colitis is the most frequent complication encountered. We found that the composition of the gut microbiota changed in ICB associated colitis. Principal component analysis of the gut microbiome showed an obvious reduction in the abundance of Lactobacillus in severe ICB associated colitis. Lactobacillus depletion completely by vancomycin augmented the immunopathology of ICB. Furthermore, we found that the ICB toxicity could be totally eliminated via the administration of a widely available probiotic Lactobacillus reuteri (L.reuteri). Oral administration of L. reuteri therapeutically inhibited the development and progression of colitis, thus ameliorating the loss of body weight and inflammatory status induced by ICB treatment. Mechanistically, the protective effect of L. reuteri was associated with a decrease in the distribution of group 3 innate lymphocytes (ILC3s) induced by ICB associated colitis. In conclusion, our study highlights the immunomodulatory mechanism of the gut microbiota and suggests that manipulating the gut microbiota by administrating L. reuteri can mitigate the autoimmunity induced by ICB, thus allowing ICB immunotherapy to stimulate the desired immune response without an apparent immunopathology. [ABSTRACT FROM AUTHOR]

Background: Understanding immune phenotypes and human gastric disease in situ requires an approach that leverages multiplexed immunohistochemistry (mIHC) with multispectral imaging to facilitate precise image analyses.Methods: We developed a novel 4-color mIHC assay based on tyramide signal amplification that allowed us to reliably interrogate immunologic checkpoints, including programmed death-ligand 1 (PD-L1), cytotoxic T cells (CD8+T) and regulatory T cells (Foxp3), in formalin-fixed, paraffin-embedded tissues of various human gastric diseases. By observing cell phenotypes within the disease tissue microenvironment, we were able to determine specific co-localized staining combinations and various measures of cell density.Results: We found that PD-L1 was expressed in gastric ulcer and in tumor cells (TCs), as well as in tumor-infiltrating immune cells (TIICs), but not in normal gastric mucosa or other gastric intraepithelial neoplastic tissues. Furthermore, we found no significant reduction in CD8+T cells, whereas the ratio of CD8+T:Foxp3 cells and CD8+T:PD-L1 cells was suppressed in tumor tissues and elevated in adjacent normal tissues. An unsupervised hierarchical analysis also identified correlations between CD8+T and Foxp3+ tumor-infiltrating lymphocyte (TIL) densities and average PD-L1 levels. Three main groups were identified based on the results of CD8+T:PD-L1 ratios in gastric tumor tissues. Furthermore, integrating CD8+T:Foxp3 ratios, which increased the complexity for immune phenotype status, revealed 6-7 clusters that enabled the separation of gastric cancer patients at the same clinical stage into different risk-group subsets.Conclusions: Characterizing immune phenotypes in human gastric disease tissues via multiplexed immunohistochemistry may help guide PD-L1 clinical therapy. Observing unique disease tissue microenvironments can improve our understanding of immune phenotypes and cell interactions within these microenvironments, providing the ability to predict safe responses to immunotherapies. [ABSTRACT FROM AUTHOR]

Background: The prognostic value of circulating tumor cells (CTCs) in ovarian cancer has been investigated in previous studies, but the results are controversial. Therefore we performed a meta-analysis to systematically review these data and evaluate the value of CTCs in ovarian cancer. Materials and Methods: A literary search for relevant studies was performed on Embase, Medline and Web of Science databases. Then pooled hazard ratios (HRs) for survival with 95% confidence intervals (CIs), subgroup analyses, sensitivity analyses, meta-regression analyses and publication bias were conducted. Results: This meta-analysis is based on 11 publications and comprises a total of 1129 patients. The prognostic value of the CTC status was significant in overall survival (OS) (HR, 1.61;95% CI,1.22–2.13) and progression-free survival (PFS)/disease-free survival (DFS) (HR, 1.44; 95%CI, 1.18–1.75). Furthermore, subgroup analysis revealed that the value of CTC status in OS was significant in "RT-PCR" subgroup (HR, 2.02; 95% CI, 1.34–3.03), whereas it was not significant in "CellSearch" subgroup (HR, 1.15; 95% CI 0.45–2.92) and "other ICC" subgroup (HR, 1.09; 95% CI 0.62–1.90). The presence of CTC was also associated with an increased CA-125 (OR, 4.07; 95%CI, 1.87–8.85). Conclusion: Our study demonstrates that CTC status is associated with OS and PFS/DFS in ovarian cancer. [ABSTRACT FROM AUTHOR]

Context: Intravenous immunoglobulin (IVIG) has been successfully applied in immune-related diseases of adults and neonates, such as human immunodeficiency virus (HIV) infection and systemic lupus erythematosus (SLE). Objective: This study aims to investigate the distinct impacts of IVIG on cultured dendritic cells (DCs) from newborn and healthy adult. Materials and methods: Blood samples were collected from eight full-term newborns and eight healthy adult volunteers. DCs from cord blood and peripheral blood were both cultured in the RPMI 1640 medium containing 10% fetal calf serum, 50 ng/ml granulocyte/macrophage colony-stimulating factor (GM-CSF) and 10 ng/ml recombinant human interleukin-4 (rhIL-4) for 5 d with therapeutic IVIG (20 mg/ml) or physiological IVIG (10 mg/ml). Lipopolysaccharides (LPSs, 1 μg/ml) were added on the fifth day to induce the maturation of immature DCs. The phagocytosis of monocytes, expression of MR (mannose receptor), CD14, CD1a, CD80, CD83, CD86 and MHC II were examined by flow cytometry. The expression of IL-4 mRNA was detected by RT-PCR, while IFN-γ, IL-12 and IL-10 were analyzed by enzyme-linked immunosorbent assay (ELISA) commercial kits. Results: IVIG of therapeutic dose inhibited the phagocytosis, differentiation and maturation of DCs, whereas physiological dose exhibited an accelerated role in vitro, especially on DCs from neonates, but aroused different effects on cytokine secretion. Discussion and conclusion: The different responses are generally due to immature immune system of neonate, which has a limit capacity to maintain immunity homeostasis. Modulation of DCs phagocytosis, differentiation, maturation and cytokine secretion by IVIG is of potential relevance to its dosage and immune status of patients. [ABSTRACT FROM AUTHOR]

Aims: Extensive evidence suggests inflammatory components participate in the pathogenic processes of acute coronary syndromes (ACS). In this study, we aimed to elucidate the role and mechanism underlying the imbalance of Th17 and Treg cell peripheral populations in the pathogenesis of ACS. Methods and Results: Using a flow cytometric analysis, we observed a significantly increased frequency of Th17 cells and a concurrently decreased CD4+CD25+Foxp3+ Treg cells in patients with ACS. To elucidate the mechanism of Th17/Treg imbalance in ACS, 22 inflammatory cytokines were measured using multiplexed immunobead-based assays. Of six elevated cytokines in ACS patients, only IL-6 was positively correlated with a higher Th17 cell level (r = 0.39, P<0.01). Relying on IL-6 stimulating and neutralizing studies, we demonstrated a direct role for IL-6 in sera from ACS patients with an increased frequency of Th17 cells. IL-6 induces the differentiation of Th17 cells from naïve CD4+ T cells through STAT3 activation and RORγt induction. However, we observed that high levels of TGF-β1 inhibited IL-6-dependent Th17 cell differentiation, indicating a complex interplay between the two cytokines in the control of Th17 and Treg cell populations. Conclusions: Our results demonstrate the role of IL-6-STAT3 signaling in ACS through increased Th17 cell differentiation. These findings indicate that IL-6 neutralizing strategies could present novel therapeutic avenues in the treatment of ACS. [ABSTRACT FROM AUTHOR]

Atherosclerosis is a progressive disease with a strong inflammatory component. Here we confirm the existence of a critical imbalance in the ratio of Th17 to Treg-cell populations in peripheral CD4+ T cells from patients with acute coronary syndrome ( ACS), which favors inflammation. This was concurrent with increased IL-17 production from the CD4+ CD45 RA− FOXP3lo Treg-cell subset, and elevated osteopontin ( OPN) levels in serum from ACS patients. We demonstrate a direct effect of OPN in serum from ACS patients on increased IL-17 production by CD4+ CD45 RA− FOXP3lo T cells, mediated through recruitment of the OPN receptors CD29 and CD44, and dependent on STAT3 and the nuclear hormone receptor retinoic-acid-related orphan receptor-γt ( RORγt) pathway, but not IL-6 production. To our knowledge and beyond the disease context of ACS, this study constitutes the first demonstration of a critical role for OPN in the positive regulation of inflammation through increased IL-17 production by CD4+ CD45 RA− FOXP3lo cells. [ABSTRACT FROM AUTHOR]

Current studies aiming at identifying single immune markers with prognostic value have limitations in the context of complex antitumor immunity and cancer immune evasion. Here, we show how the integration of several immune markers influences the predictions of prognosis of gastric cancer (GC) patients. We analyzed Tissue Microarray (TMA) by multiplex immunohistochemistry and measured the expression of immune checkpoint molecule PD-L1 together with antitumor CD8 T cells and immune suppressive FOXP3 Treg cells in a cohort of GC patients. Unsupervised hierarchical clustering analysis of these markers was used to define correlations between CD8 T, FOXP3 Treg and PD-L1 cell densities. We found that FOXP3 and PD-L1 densities were elevated while CD8 T cells were decreased in tumor tissues compared to their adjacent normal tissues. However, patient stratification based on each one of these markers individually did not show significant prognostic value on patient survival. Conversely, combination of the ratios of CD8/FOXP3 and CD8/PD-L1 enabled the identification of patient subgroups with different survival outcomes. As such, high densities of PD-L1 in patients with high CD8/FOXP3 and low CD8/PD-L1 ratios correlated with increased survival. Collectively, this work demonstrates the need for the integration of several immune markers to obtain more meaningful survival prognosis and patient stratification. In addition, our work provides insights into the complex tumor immune evasion and immune regulation by the tumor-infiltrating effector and suppressor cells, informing on the best use of immunotherapy options for treating patients. [ABSTRACT FROM AUTHOR]