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Colorectal carcinoma (CRC) represents a lethal disease with heterogeneous outcomes. Only patients with mismatch repair (MMR) deficient CRC showing microsatellite instability and hyper-mutated tumors can obtain clinical benefits from current immune checkpoint blockades; on the other hand, immune- or target-based therapeutic strategies are very limited for subjects with mismatch repair proficient CRC (CRCpMMR). Here, we report a comprehensive typing of immune infiltrating cells in CRCpMMR. We also tested the expression and interferon-γ-modulation of PD-L1/CD274. Relevant findings were subsequently validated by immunohistochemistry on fixed materials. CRCpMMR contain a significantly increased fraction of CD163+ macrophages (TAMs) expressing TREM2 and CD66+ neutrophils (TANs) together with decrease in CD4−CD8−CD3+ double negative T lymphocytes (DNTs); no differences were revealed by the analysis of conventional and plasmacytoid dendritic cell populations. A fraction of tumor-infiltrating T-cells displays an exhausted phenotype, co-expressing PD-1 and TIM-3. Remarkably, expression of PD-L1 on fresh tumor cells and TAMs was undetectable even after in vitro stimulation with interferon-γ. These findings confirm the immune suppressive microenvironment of CRCpMMR characterized by dense infiltration of TAMs, occurrence of TANs, lack of DNTs, T-cell exhaustion, and interferon-γ unresponsiveness by host and tumor cells. Appropriate bypass strategies should consider these combinations of immune escape mechanisms in CRCpMMR.

CRCMSS/pMMR contain a significantly increased fraction of TREM2+ macrophages (TAMs) and CD66+ neutrophils (TANs) together with decrease of CD4-CD8-CD3+ double negative T lymphocytes (DNTs); no differences were revealed by the analysis of myeloid and plasmacytoid dendritic cell populations. A fraction of tumor-infiltrating T-cells display an exhausted phenotype, co-expressing PD-1 and TIM-3. Remarkably, expression of PD-L1 on fresh tumor cells and TAMs was undetectable even after in vitro stimulation with interferon-γ. These findings confirm the immune suppressive microenvironment of CRCMSS/pMMR characterized by dense infiltration of TAMs, occurrence of TANs, lack of DNTs, T-cell exhaustion and interferon-γ unresponsiveness by host and tumor cells. Appropriate bypass strategies should consider these combinations of immune escape mechanisms in CRCMSS/pMMR.

Supplementary Figures 1-9

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by tissue accumulation of CD1a+CD207+ LCH cells. In LCH, somatic mutations of the BRAFV600E gene have been detected in tissue LCH cells, bone marrow CD34+ hematopoietic stem cells, circulating CD14+ monocytes, and BDCA1+ myeloid dendritic cells (DC). Targeting BRAFV600E in clonal Langerhans cells (LC) and their precursors is a potential treatment option for patients whose tumors have the mutation. The development of mouse macrophages and LCs is regulated by the CSF1 receptor (CSF1R). In patients with diffuse-type tenosynovial giant cell tumors, CSF1R inhibition depletes tumor-associated macrophages (TAM) with therapeutic efficacy; however, CSF1R signaling in LCs and LCH has not been investigated. We found through IHC and flow cytometry that CSF1R is normally expressed on human CD1a+CD207+ LCs in the epidermis and stratified epithelia. LCs that were differentiated from CD14+ monocytes, BDCA1+ DCs, and CD34+ cord blood progenitors expressed CSF1R that was downregulated upon maturation. Immature LCs migrated toward CSF1, but not IL34. Administration of the c-FMS/CSF1R kinase inhibitors GW2580 and BLZ945 significantly reduced human LC migration. In LCH clinical samples, LCH cells (including BRAFV600E cells) and TAMs retained high expression of CSF1R. We also detected the presence of transcripts for its ligand, CSF1, but not IL34, in all tested LCH cases. CSF1R and CSF1 expression in LCH, and their role in LC migration and differentiation, suggests CSF1R signaling blockade as a candidate rational approach for treatment of LCH, including the BRAFV600E and wild-type forms of the disease.

Supplementary Tables 1-2

Supplementary figures 1-5, supplementary tables 1-9

Follicular dendritic cell (FDC) sarcomas are rare mesenchymal tumors with variable clinical, morphologic, and phenotypic characteristics. Transcriptome analysis was performed on multiple FDC sarcomas and compared with other mesenchymal tumors, microdissected Castleman FDCs, and normal fibroblasts. Using unsupervised analysis, FDC sarcomas clustered with microdissected FDCs, distinct from other mesenchymal tumors and fibroblasts. The specific endowment of FDC-related gene expression programs in FDC sarcomas emerged by applying a gene signature of differentially expressed genes (n = 1,289) between microdissected FDCs and fibroblasts. Supervised analysis comparing FDC sarcomas with microdissected FDCs and other mesenchymal tumors identified 370 and 2,927 differentially expressed transcripts, respectively, and on the basis of pathway enrichment analysis ascribed to signal transduction, chromatin organization, and extracellular matrix organization programs. As the transcriptome of FDC sarcomas retained similarity with FDCs, the immune landscape of FDC sarcoma was investigated by applying the CIBERSORT algorithm to FDC sarcomas and non-FDC mesenchymal tumors and demonstrated that FDC sarcomas were enriched in T follicular helper (TFH) and T regulatory (TREG) cell populations, as confirmed in situ by immunohistochemistry. The enrichment in specific T-cell subsets prompted investigating the mRNA expression of the inhibitory immune receptor PD-1 and its ligands PD-L1 and PD-L2, which were found to be significantly upregulated in FDC sarcomas as compared with other mesenchymal tumors, a finding also confirmed in situ. Here, it is demonstrated for the first time the transcriptional relationship of FDC sarcomas with nonmalignant FDCs and their distinction from other mesenchymal tumors.Implications: The current study provides evidence of a peculiar immune microenvironment associated with FDC sarcomas that may have clinical utility. Mol Cancer Res; 15(5); 541–52. ©2017 AACR.

These supplementary figures show the in vitro cell culture strategies utilized in this study to demonstrate the requirement of ERK5 signaling for mediating tumor macrophage proliferation.

MEK inhibition blocks FDC-S cell growth in a dose-dependent manner.

These supplementary figures show the strategies utilized to analyze populations of circulating monocytes, and alveolar and interstitial macrophages in the lung of B16-F10-bearing mice by flow cytometry.

Technical details of the Material and Methods section and legend to Supplementary Figures

Terminal tissue differentiation and function of slan+ monocytes in cancer is largely unexplored. Our recent studies demonstrated that slan+ monocytes differentiate into a distinct subset of dendritic cells (DC) in human tonsils and that slan+ cells colonize metastatic carcinoma-draining lymph nodes. Herein, we report by retrospective analysis of multi-institutional cohorts that slan+ cells infiltrate various types of non-Hodgkin lymphomas (NHL), particularly the diffuse large B-cell lymphoma (DLBCL) group, including the most aggressive, nodal and extranodal, forms. Nodal slan+ cells displayed features of either immature DC or macrophages, in the latter case ingesting tumor cells and apoptotic bodies. We also found in patients with DLBCL that peripheral blood slan+ monocytes, but not CD14+ monocytes, increased in number and displayed highly efficient rituximab-mediated antibody-dependent cellular cytotoxicity, almost equivalent to that exerted by NK cells. Notably, slan+ monocytes cultured in conditioned medium from nodal DLBCL (DCM) acquired a macrophage-like phenotype, retained CD16 expression, and became very efficient in rituximab-mediated antibody-dependent cellular phagocytosis (ADCP). Macrophages derived from DCM-treated CD14+ monocytes performed very efficient rituximab-mediated ADCP, however, using different FcγRs from those used by slan+ macrophages. Our observations shed new light on the complexity of the immune microenvironment of DLBCL and demonstrate plasticity of slan+ monocytes homing to cancer tissues. Altogether, data identify slan+ monocytes and macrophages as prominent effectors of antibody-mediated tumor cell targeting in patients with DLBCL.Significance: slan+ monocytes differentiate into macrophages that function as prominent effectors of antibody-mediated tumor cell targeting in lymphoma.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/13/3544/F1.large.jpg. Cancer Res; 78(13); 3544–59. ©2018 AACR.

The file contains 8 supplementary Figures displaying results in support of the data described in the results section.

Purpose: The aim of this study was to investigate the biological and clinical significance of epidermal growth factor receptor (EGFR) signaling pathway in follicular dendritic cell sarcoma (FDC-S).Experimental Design: Expression of EGFR and cognate ligands as well as activation of EGFR signaling components was assessed in clinical samples and in a primary FDC-S short-term culture (referred as FDC-AM09). Biological effects of the EGFR antagonists cetuximab and panitumumab and the MEK inhibitor UO126 on FDC-S cells were determined in vitro on FDC-AM09. Direct sequencing of KRAS, BRAF, and PI3KCA was conducted on tumor DNA.Results: We found a strong EGFR expression on dysplastic and neoplastic FDCs. On FDC-AM09, we could show that engagement of surface EGFR by cognate ligands drives the survival and proliferation of FDC-S cells, by signaling to the nucleus mainly via MAPK and STAT pathways. Among EGFR ligands, heparin-binding EGF-like growth factor, TGF-α and Betacellulin (BTC) are produced in the tumor microenvironment of FDC-S at RNA level. By extending this finding at protein level we found that BTC is abundantly produced by FDC-S cells and surrounding stromal cells. Finally, direct sequencing of tumor-derived genomic DNA showed that mutations in KRAS, NRAS, BRAF, and PI3KCA, which predicts resistance to anti-EGFR MoAb in other cancer models, are not observed in FDC-S.Conclusion: Activation of EGFR by cognate ligands produced in the tumor microenvironment sustain viability and proliferation of FDC-S indicating that the receptor blockade might be clinically relevant in this neoplasm. Clin Cancer Res; 19(18); 5027–38. ©2013 AACR.

These supplementary data provide evidence that human tumors comprise a high proportion of proliferating TAMs expressing ERK5 in the nucleus, scattered around the tumor tissue.

Expression of EGFR by FDC FRC on human lymph nodes.

This supplementary figure confirms that ERK5 ablation significantly reduces TAM density in melanoma metastases.

These supplementary data show that the reduction in the number of TAMs caused by myeloid ERK5 deficiency correlates with reduced melanoma cell proliferation in melanoma grafts.

The presence of immunosuppressive macrophages that become activated in the tumor microenvironment constitutes a major factor responsible for tumor growth and malignancy. In line with this knowledge, we report here that macrophage proliferation is a significant feature of advanced stages of cancer. Moreover, we have found that a high proportion of proliferating macrophages in human tumors express ERK5. ERK5 was required for supporting the proliferation of macrophages in tumor grafts in mice. Furthermore, myeloid ERK5 deficiency negatively impacted the proliferation of both resident and infiltrated macrophages in metastatic lung nodules. ERK5 maintained the capacity of macrophages to proliferate by suppressing p21 expression to halt their differentiation program. Collectively, these data provide insight into the mechanism underpinning macrophage proliferation to support malignant tumor development, thereby strengthening the value of ERK5-targeted therapies to restore antitumor immunity through the blockade of protumorigenic macrophage activation.Significance:These findings offer a new rationale for anti-ERK5 therapy to improve cancer patient outcomes by blocking the proliferative activity of tumor macrophages.

This file contains Supplementary Methods for i) isolating single cells from murine tumors and lungs, ii) magnetic bead purification of tumor-associated macrophages and monocytes, and iii) EdU labelling and staining; and Supplementary legends for Figures S1 to S13.

10 Tables displaying the clinical features of patient cohorts analyzed in this study, as well as correlation analyses among the clinical features and slan+ cell content.

Table S1: A list of the primer sequences utilized for qRT- PCR experiments Table S2: Total number of proliferating CD163+ and Iba1+ cells in human and murine tumors.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can be demonstrated in tissue sections by immunohistochemistry (IHC), which has the power to localize in bright field specific antigens in cells and tissues. The use of double or triple immunostains is capable of highlighting which cells are infected and/or the relationship of infected cell with other cells and tissue structures. In addition, immunoenzymatic multi-staining permits the simultaneous identification, localization, and enumeration of different cellular epitopes. Moreover, this method improves analytical precision, decreasing the time required for morphometric quantification, maximizing the information obtained from a single slide of paraffin-embedded tissue.

Contains fulltext : 251438.pdf (Publisher’s version ) (Open Access) For high-risk endometrial cancer (EC) patients, adjuvant chemotherapy is recommended to improve outcome. Yet, predictive biomarkers for response to platinum-based chemotherapy (Pt-aCT) are currently lacking. We tested expression of L1 cell-adhesion molecule (L1CAM), a well-recognised marker of poor prognosis in EC, in tumour samples from high-risk EC patients, to explore its role as a predictive marker of Pt-aCT response. L1CAM expression was determined using RT-qPCR and immunohistochemistry in a cohort of high-risk EC patients treated with Pt-aCT and validated in a multicentric independent cohort. The association between L1CAM and clinicopathologic features and L1CAM additive value in predicting platinum response were determined. The effect of L1CAM gene silencing on response to carboplatin was functionally tested on primary L1CAM-expressing cells. Increased L1CAM expression at both genetic and protein level correlated with high-grade, non-endometrioid histology and poor response to platinum treatment. A predictive model adding L1CAM to prognostic clinical variables significantly improved platinum response prediction (C-index 78.1%, P = .012). In multivariate survival analysis, L1CAM expression was significantly associated with poor outcome (HR: 2.03, P = .019), potentially through an indirect effect, mediated by its influence on response to chemotherapy. In vitro, inhibition of L1CAM significantly increased cell sensitivity to carboplatin, supporting a mechanistic link between L1CAM expression and response to platinum in EC cells. In conclusion, we have demonstrated the role of L1CAM in the prediction of response to Pt-aCT in two independent cohorts of high-risk EC patients. L1CAM is a promising candidate biomarker to optimise decision making in high-risk patients who are eligible for Pt-aCT.

Simple Summary Alterations of the MEK5/ERK5 signaling pathway have been described in several tumors, and emerging data are trying to explain the complexity of ERK5-related mechanisms in both physiological and pathological conditions. Here, we provide an overview of the known evidence about ERK5 expression, activity, and regulation in tumors. Moreover, our study investigated the clinical significance and the prognostic value of ERK5 deregulation in human cancer. Upregulation and overexpression of ERK5 were reported in several tumor types associated with advanced stage, metastases, and worse overall survival. In addition, we focus on emerging insights regarding the relevance of ERK5 in a tumor-associated microenvironment. Finally, the recently discovered ERK5 isoforms, correlated with pro-tumoral function and negative regulation of ERK5, were also described. Abstract Extracellular signal-regulated kinase 5 (ERK5) is a unique kinase among MAPKs family members, given its large structure characterized by the presence of a unique C-terminal domain. Despite increasing data demonstrating the relevance of the ERK5 pathway in the growth, survival, and differentiation of normal cells, ERK5 has recently attracted the attention of several research groups given its relevance in inflammatory disorders and cancer. Accumulating evidence reported its role in tumor initiation and progression. In this review, we explore the gene expression profile of ERK5 among cancers correlated with its clinical impact, as well as the prognostic value of ERK5 and pERK5 expression levels in tumors. We also summarize the importance of ERK5 in the maintenance of a cancer stem-like phenotype and explore the major known contributions of ERK5 in the tumor-associated microenvironment. Moreover, although several questions are still open concerning ERK5 molecular regulation, different ERK5 isoforms derived from the alternative splicing process are also described, highlighting the potential clinical relevance of targeting ERK5 pathways.

Simple Summary In the tumor microenvironment, interaction among tumor cells, immune cells, stromal cells, and the extracellular matrix is vital to support pro-tumor mechanisms such as drug resistance and metastases. Malignant pleural mesothelioma has a unique and complex tumor microenvironment. Several reports underlined the key role of immune and stromal cells in tumorigenesis and progression of mesothelioma. These non-cancer cells, via a reciprocal informational exchange with tumor cells, established a chronic inflammatory microenvironment that support the malignancy and the chemoresistant phenotype of the tumor. The knowledge of the cellular and molecular mechanisms underlying tumor microenvironment interconnection was recently considered a crucial point for the design of more effective therapeutic strategies. In this review, we summarize the molecular mechanisms by which stroma and immune cells support the malignancy of mesothelioma and their potential therapeutic targeting. Abstract Several studies have reported that cellular and soluble components of the tumor microenvironment (TME) play a key role in cancer-initiation and progression. Considering the relevance and the complexity of TME in cancer biology, recent research has focused on the investigation of the TME content, in terms of players and informational exchange. Understanding the crosstalk between tumor and non-tumor cells is crucial to design more beneficial anti-cancer therapeutic strategies. Malignant pleural mesothelioma (MPM) is a complex and heterogenous tumor mainly caused by asbestos exposure with few treatment options and low life expectancy after standard therapy. MPM leukocyte infiltration is rich in macrophages. Given the failure of macrophages to eliminate asbestos fibers, these immune cells accumulate in pleural cavity leading to the establishment of a unique inflammatory environment and to the malignant transformation of mesothelial cells. In this inflammatory landscape, stromal and immune cells play a driven role to support tumor development and progression via a bidirectional communication with tumor cells. Characterization of the MPM microenvironment (MPM-ME) may be useful to understand the complexity of mesothelioma biology, such as to identify new molecular druggable targets, with the aim to improve the outcome of the disease. In this review, we summarize the known evidence about the MPM-ME network, including its prognostic and therapeutic relevance.

Oral cavity squamous cell carcinoma (OSCC) is a common head and neck cancer characterized by a poor prognosis associated with locoregional or distant failure. Among the predictors of prognosis, a dense infiltration of adaptive immune cells is protective and associated with improved clinical outcomes. However, few tools are available to integrate immune contexture variables into clinical settings. By using digital microscopy analysis of a large retrospective OSCC cohort (n = 182), we explored the clinical significance of tumor-infiltrating CD8+ T-cells. To this end, CD8+ T-cells counts were combined with well-established clinical variables and peripheral blood immune cell parameters. Through variable clustering, five metavariables (MV) were obtained and included descriptors of nodal (NODALMV) and primary tumor (TUMORMV) involvement, the frequency of myeloid (MYELOIDMV) or lymphoid (LYMPHOIDMV) peripheral blood immune cell populations, and the density of tumor-infiltrating CD8+ T-cells (TI-CD8MV). The clinical relevance of the MV was evaluated in the multivariable survival models. The NODALMV was significantly associated with all tested outcomes (p &lt, 0.001), the LYMPHOIDMV showed a significant association with the overall, disease-specific and distant recurrence-free survival (p &lt, 0.05) and the MYELOIDMV with the locoregional control only (p &lt, 0.001). Finally, TI-CD8MV was associated with distant recurrence-free survival (p = 0.029). Notably, the performance in terms of survival prediction of the combined effect of NODALMV and immune metavariables (LYMPHOIDMV, MYELOIDMV and TI-CD8MV) was superior to the TNM stage for most of the outcomes analyzed. These findings indicate that the analysis of the baseline host immune features are promising tools to complement clinical features, in stratifying the risk of recurrences.

The plasma membrane tetraspan molecule MS4A4A is selectively expressed by macrophage-lineage cells, but its function is unknown. Here we report that MS4A4A was restricted to murine and human mononuclear phagocytes and was induced during monocyte-to-macrophage differentiation in the presence of interleukin 4 or dexamethasone. Human MS4A4A was co-expressed with M2/M2-like molecules in subsets of normal tissue-resident macrophages, infiltrating macrophages from inflamed synovium and tumor-associated macrophages. MS4A4A interacted and colocalized with the β-glucan receptor dectin-1 in lipid rafts. In response to dectin-1 ligands, Ms4a4a-deficient macrophages showed defective signaling and defective production of effector molecules. In experimental models of tumor progression and metastasis, Ms4a4a deficiency in macrophages had no impact on primary tumor growth, but was essential for dectin-1-mediated activation of macrophages and natural killer (NK) cell–mediated metastasis control. Thus, MS4A4A is a tetraspan molecule selectively expressed in macrophages during differentiation and polarization, essential for dectin-1-dependent activation of NK cell–mediated resistance to metastasis.

Tumours derived from histiocytes/macrophages and from dendritic cells are extremely rare. They mainly occur in lymphoid tissues, where they account for less than 1% of tumours, but they can be also found in extranodal sites. These neoplasms represent a heterogeneous group of diseases with a variable clinical behavior even within the same tumour entity, ranging from localized and indolent forms to systemic aggressive processes. Diagnosis is based on histological and immunophenotypic features, but overlaps occur across diseases with different biological nature and clinical course, thus correlation with clinical and radiological features is sometimes necessary for final diagnosis. The driver mutations identified during the last few years contributed to a better understanding of the pathogenesis of some of these tumours and in some of them turned out to be useful for diagnosis and treatment.

Here we report the identification of human CD66b

Objectives The role of tumor‐associated neutrophils (TANs) in the nodal spread of cancer cells remains unexplored. The present study evaluates the occurrence and clinical significance of human nodal TANs. Methods The relevance, derivation, phenotype and interactions of nodal TANs were explored via a large immunohistochemical analysis of carcinoma‐draining lymph nodes, and their clinical significance was evaluated on a retrospective cohort of oral squamous cell carcinomas (OSCC). The tumor‐promoting function of nodal TAN was probed in the OSCC TCGA dataset combining TAN and epithelial‐to‐mesenchymal transition (EMT) signatures. Results The pan‐carcinoma screening identified a consistent infiltration (59%) of CD66b+ TANs in tumor‐draining lymph nodes (TDLNs). Microscopic findings, including the occurrence of intra‐lymphatic conjugates of TANs and cancer cells, indicate that TANs migrate through lymphatic vessels. In vitro experiments revealed that OSCC cell lines sustain neutrophil viability and activation via release of GM‐CSF. Moreover, by retrospective analysis, a high CD66b+ TAN density in M‐TDLNs of OSCC (n = 182 patients) predicted a worse prognosis. The analysis of the OSCC‐TCGA dataset unveiled that the expression of a set of neutrophil‐specific genes in the primary tumor (PT) is highly associated with an EMT signature, which predicts nodal spread. Accordingly, in the PT of OSCC cases, CD66b+TANs co‐localised with PDPN+S100A9− EMT‐switched tumor cells in areas of lymphangiogenesis. The pro‐EMT signature is lacking in peripheral blood neutrophils from OSCC patients, suggesting tissue skewing of TANs. Conclusion Our findings are consistent with a novel pro‐tumoral TAN compartment that may promote nodal spread via EMT, through the lymphatics., Our findings propose a novel pro‐tumoral TAN (tumor‐associated neutrophil) compartment with a role in promoting the nodal metastatic colonisation via EMT (epithelial‐to‐mesenchymal transition), through the lymphatic route.

Simple Summary The pathogenesis of CRC relies on complex interactions between developing cancer and surrounding tissue, including the immune system. One of the most abundant tumor-infiltrating cell populations is represented by tumor-associated macrophages (TAMs). TAMs play a detrimental role and are associated with a poor prognosis in many tumors and are characterized by an impaired antigen-presenting capability and by immunosuppressive activity. However, their role in CRC is still controversial. Our study aimed to elucidate how the colorectal cancer environment educates macrophages toward a pro-tumoral profile, exploiting them to escape the immune response. We demonstrate that both CRC cells and the extracellular matrix are actively involved in defining the macrophage profile, which is characterized by immunosuppressive activity and an impaired antigen-presenting ability. Dissecting the contribution of the tumor environment to the influence on the macrophage profile will provide additional knowledge for the development of new antitumor strategies. Abstract Tumor-associated macrophages (TAMs) are major components of the tumor microenvironment. In colorectal cancer (CRC), a strong infiltration of TAMs is accompanied by a decrease in effector T cells and an increase in the metastatic potential of CRC. We investigated the functional profile of TAMs infiltrating CRC tissue by immunohistochemistry, flow cytometry, ELISA, and qRT-PCR and their involvement in impairing the activation of effector T cells. In CRC biopsies, we evidenced a high percentage of macrophages with low expression of the antigen-presenting complex MHC-II and high expression of CD206. Monocytes co-cultured with tumor cells or a decellularized tumor matrix differentiated toward a pro-tumoral macrophage phenotype characterized by decreased expression of MHC-II and CD86 and increased expression of CD206 and an abundant release of pro-tumoral cytokines and chemokines. We demonstrated that the hampered expression of MHC-II in macrophages is due to the downregulation of the MHC-II transactivator CIITA and that this effect relies on increased expression of miRNAs targeting CIITA. As a result, macrophages become unable to present antigens to CD4 T lymphocytes. Our data suggest that the tumor microenvironment contributes to defining a pro-tumoral profile of macrophages infiltrating CRC tissue with impaired capacity to activate T cell effector functions.

Supplemental Digital Content is available in the text., Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive neoplasm derived from plasmacytoid dendritic cells (pDCs). In this study, we investigated by immunohistochemical analysis the expression of E-cadherin (EC) on pDCs in reactive lymph nodes and tonsils, bone marrow, and in BPDCN. We compared the expression of EC in BPDCN to that in leukemia cutis (LC) and cutaneous lupus erythematosus (CLE), the latter typically featuring pDC activation. In BPDCN, we also assessed the immunomodulatory activity of malignant pDCs through the expression of several type I interferon (IFN-I) signaling effectors and downstream targets, PD-L1/CD274, and determined the extent of tumor infiltration by CD8-expressing T cells. In reactive lymph nodes and tonsils, pDCs expressed EC, whereas no reactivity was observed in bone marrow pDCs. BPDCN showed EC expression in the malignant pDCs in the vast majority of cutaneous (31/33 cases, 94%), nodal, and spleen localizations (3/3 cases, 100%), whereas it was more variable in the bone marrow (5/13, 38,5%), where tumor cells expressed EC similarly to the skin counterpart in 4 cases and differently in other 4. Notably, EC was undetectable in LC (n=30) and in juxta-epidermal pDCs in CLE (n=31). Contrary to CLE showing robust expression of IFN-I-induced proteins MX1 and ISG5 in 20/23 cases (87%), and STAT1 phosphorylation, BPDCN biopsies showed inconsistent levels of these proteins in most cases (85%). Expression of IFN-I-induced genes, IFI27, IFIT1, ISG15, RSAD2, and SIGLEC1, was also significantly (P

Osteosarcomas (OSs) are bone tumors most commonly found in pediatric and adolescent patients characterized by high risk of metastatic progression and recurrence after therapy. Effective therapeutic management of this disease still remains elusive as evidenced by poor patient survival rates. To achieve a more effective therapeutic management regimen, and hence patient survival, there is a need to identify more focused targeted therapies for OSs treatment in the clinical setting. The role of the OS tumor stroma microenvironment plays a significant part in the development and dissemination of this disease. Important components, and hence potential targets for treatment, are the tumor-infiltrating macrophages that are known to orchestrate many aspects of OS stromal signaling and disease progression. In particular, increased infiltration of M2-like tumor-associated macrophages (TAMs) has been associated with OS metastasis and poor patient prognosis despite currently used aggressive therapies regimens. This review aims to provide a summary update of current macrophage-centered knowledge and to discuss the possible roles that macrophages play in the process of OS metastasis development focusing on the potential influence of stromal cross-talk signaling between TAMs, cancer-stem cells and additional OSs tumoral microenvironment factors.