The tumor microenvironment drives NK cell metabolic dysfunction leading to impaired antitumor activity.

NK cells represent key players capable of driving antitumor immune responses. However, the potent immunosuppressive activity of the tumor microenvironment (TME) may impair their effector function. Here, we strengthen the importance of metabolic interactions between NK cells and TME and propose metabolic dysfunction as one of the major mechanisms behind NK failure in cancer treatment. In particular, we described that TME has a direct negative impact on NK cell function by disrupting their mitochondrial integrity and function in pediatric and adult patients with primary and metastatic cancer. Our results will help to design new strategies aimed at increasing the NK cell antitumor efficacy by their metabolic reprogramming. In this regard, we reveal an unprecedented role of IL15 in the metabolic reprogramming of NK cells enhancing their antitumor functions. IL15 prevents the inhibitory effect of soluble factors present in TME and restores both the metabolic characteristics and the effector function of NK cells inhibited by exposure to malignant pleural fluid. Thus, we propose here that IL15 may be exploited as a new strategy to metabolically reprogram NK cells with the aim of increasing the efficacy of NK-based immunotherapy in a wide range of currently refractory adult and pediatric solid tumors.

IRAK1 Duplication in MECP2 Duplication Syndrome Does Not Increase Canonical NF-κB-Induced Inflammation.

PURPOSE: Besides their developmental and neurological phenotype, most patients with MECP2/IRAK1 duplication syndrome present with recurrent and severe infections, accompanied by strong inflammation. Respiratory infections are the most common cause of death. Standardized pneumological diagnostics, targeted anti-infectious treatment, and knowledge of the underlying pathomechanism that triggers strong inflammation are unmet clinical needs. We investigated the influence of IRAK1 overexpression on the canonical NF-κB signaling as a possible cause for excessive inflammation in these patients. METHODS: NF-κB signaling was examined by measuring the production of proinflammatory cytokines and evaluating the IRAK1 phosphorylation and degradation as well as the IκBα degradation upon stimulation with IL-1ß and TLR agonists in SV40-immortalized fibroblasts, PBMCs, and whole blood of 9 patients with MECP2/IRAK1 duplication syndrome, respectively. RESULTS: Both, MECP2/IRAK1-duplicated patients and healthy controls, showed similar production of IL-6 and IL-8 upon activation with IL-1ß and TLR2/6 agonists in immortalized fibroblasts. In PBMCs and whole blood, both patients and controls had a similar response of cytokine production after stimulation with IL-1ß and TLR4/2/6 agonists. Patients and controls had equivalent patterns of IRAK1 phosphorylation and degradation as well as IκBα degradation upon stimulation with IL-1ß. CONCLUSION: Patients with MECP2/IRAK1 duplication syndrome do not show increased canonical NF-κB signaling in immortalized fibroblasts, PBMCs, and whole blood. Therefore, we assume that these patients do not benefit from a therapeutic suppression of this pathway.

Glucocorticoids and the cytokines IL-12, IL-15, and IL-18 present in the tumor microenvironment induce PD-1 expression on human natural killer cells.

BACKGROUND: Programmed cell death protein 1 (PD-1)-immune checkpoint blockade has provided significant clinical efficacy across various types of cancer by unleashing both T and natural killer (NK) cell-mediated antitumor responses. However, resistance to immunotherapy occurs for many patients, rendering the identification of the mechanisms that control PD-1 expression extremely important to increase the response to the therapy. OBJECTIVE: We sought to identify the stimuli and the molecular mechanisms that induce the de novo PD-1 expression on human NK cells in the tumor setting. METHODS: NK cells freshly isolated from peripheral blood of healthy donors were stimulated with different combinations of molecules, and PD-1 expression was studied at the mRNA and protein levels. Moreover, ex vivo analysis of tumor microenvironment and NK cell phenotype was performed. RESULTS: Glucocorticoids are indispensable for PD-1 induction on human NK cells, in cooperation with a combination of cytokines that are abundant at the tumor site. Mechanistically, glucocorticoids together with IL-12, IL-15, and IL-18 not only upregulate PDCD1 transcription, but also activate a previously unrecognized transcriptional program leading to enhanced mRNA translation and resulting in an increased PD-1 amount in NK cells. CONCLUSIONS: These results provide evidence of a novel immune suppressive mechanism of glucocorticoids involving the transcriptional and translational control of an important immune checkpoint.

Fibromyalgia and Nutrition: An Updated Review.

Due to the lack of specific and standardized treatments for the management of fibromyalgia (FM), available evidence suggests a multidisciplinary approach, and nutrition represents an important therapeutic strategy. This work aims to update the relationship between FM and nutrition, through a review of more recent scientific evidence based on a systematic research on PubMed. Of 66 records initially identified, 26 studies were selected and included in the present work. Although there is not sufficient evidence for the efficacy of specific nutritional protocols, the examined papers indicate a potential role of selected nutrients, micronutrients and food components in managing FM symptoms. However, several concerns persist as nutritional status and/or nutritional integration can improve FM symptoms, without expecting to lead to a remission of the disease. The use of targeted nutritional supplements may be of some relevance for the management of FM, but the up to date evidence remains weak. It is advisable, thus, to perform further studies of higher quality.KEY TEACHING POINTSFibromyalgia (FM) is characterized by chronic and diffuse musculoskeletal pain, often associated with a large set of symptoms.The therapeutic approach of FM include pharmacological and non-pharmacological interventions. Among them, an important role is played by nutrition.Of 66 record screened, 12 studies were included in the present review and five of them were randomized controlled trials. Nevertheless, the overall quality of those trials was scarce.Literature concerning FM and nutritions is growing. However, little evidence suggests that nutrition and/or nutritional intervention play a significant role on FM severity.The results of this review underline the need to carry out clinical studies of higher quality and rigor, possibly RCTs, focused on the role of nutrition in the symptoms and/or severity of FM.

Presence of innate lymphoid cells in pleural effusions of primary and metastatic tumors: Functional analysis and expression of PD-1 receptor.

The tumor microenvironment (TM) contains a wide variety of cell types and soluble factors capable of suppressing immune responses. While the presence of NK cells in pleural effusions (PE) has been documented, no information exists on the presence of other innate lymphoid cell (ILC) subsets and on the expression of programmed cell death-1 (PD-1) in NK and ILC. The presence of ILC was assessed in PE of 54 patients (n = 33 with mesothelioma, n = 15 with adenocarcinoma and n = 6 with inflammatory pleural diseases) by cell staining with suitable antibody combinations and cytofluorimetric analysis. The cytokine production of ILC isolated from both PE and autologous peripheral blood was analyzed upon cell stimulation and intracytoplasmic staining. We show that, in addition to NK cells, also ILC1, ILC2 and ILC3 are present in malignant PE and that the prevalent subset is ILC3. PE-ILC subsets produced their typical sets of cytokines upon activation. In addition, we analyzed the PD-1 expression on NK/ILC by multiparametric flow-cytometric analysis, while the expression of PD-1 ligand (PD-L1) was evaluated by immunohistochemical analysis. Both NK cells and ILC3 expressed functional PD-1, moreover, both tumor samples and malignant PE-derived tumor cell lines were PD-L1+ suggesting that the interaction between PD-1+ ILC and PD-L1+ tumor cells may hamper antitumor immune responses mediated by NK and ILC.

Supratotal Resection of Glioblastoma: Is Less More?

BACKGROUND: A relationship between the extent of resection (EOR) and survival has been demonstrated in patients with glioblastomas (GBMs). However, despite gross total resection (GTR) of the enhancing nodule (EN), GBMs usually relapse, generally near the surgical cavity. OBJECTIVE: The aim of this study was to determine the prognostic role of FLAIR resection of GBMs by analyzing pre- and post-operative MRIs to estimate the EOR of EN, FLAIR-hyperintense regions and total tumor volume (TTV). METHODS: Radiologic and clinical outcomes were analyzed retrospectively. Pre- and post-operative EN volume, pre- and postoperative FLAIR volume (POFV), and pre- and postoperative TTV were analyzed. EOR was then calculated for each component. Time-dependent ROC curves and cut-off values for pre- and post-operative volumes and EOR were calculated. A Kaplan-Meier analysis with the log-rank test and Cox regression analysis were then used to analyze progression-free survival (PFS) and overall survival (OS). RESULTS: We did not find any correlation between EOR of FLAIR-altered regions and patient survival. On the other hand, there were statistically significant relationships between the prognosis and both a preoperative EN volume less than 31.35 cm3 (p=0.032) and a postoperative EN volume less than 0.57 cm3 (p=0.015). Moreover, an EOR of EN greater than 96% was significantly associated with the prognosis (p=0.0051 for OS and p=0.022 for PFS). CONCLUSION: Our retrospective, multi-center study suggests that survival in patients with GBM is not affected by the extent of resection of FLAIR-hyperintense areas.

Cardiac Nerve Growth Factor Overexpression Induces Bone Marrow-derived Progenitor Cells Mobilization and Homing to the Infarcted Heart.

Reparative response by bone marrow (BM)-derived progenitor cells (PCs) to ischemia is a multistep process that comprises the detachment from the BM endosteal niche through activation of osteoclasts and proteolytic enzymes (such as matrix metalloproteinases (MMPs)), mobilization to the circulation, and homing to the injured tissue. We previously showed that intramyocardial nerve growth factor gene transfer (NGF-GT) promotes cardiac repair following myocardial infarction (MI) in mice. Here, we investigate the impact of cardiac NGF-GT on postinfarction BM-derived PCs mobilization and homing at different time points after adenovirus-mediated NGF-GT in mice. Immunohistochemistry and flow cytometry newly illustrate the temporal profile of osteoclast and activation of MMP9, PCs expansion in the BM, and liberation/homing to the injured myocardium. NGF-GT amplified these responses and increased the BM levels of active osteoclasts and MMP9, which were not observed in MMP9-deficient mice. Taken together, our results suggest a novel role for NGF in BM-derived PCs mobilization/homing following MI.

Characterization of human afferent lymph dendritic cells from seroma fluids.

Dendritic cells (DCs) migrate from peripheral tissues to secondary lymphoid organs (SLOs) through the afferent lymph. Owing to limitations in investigating human lymph, DCs flowing in afferent lymph have not been properly characterized in humans until now. In this study, DCs present in seroma, an accrual of human afferent lymph occurring after lymph node surgical dissection, were isolated and analyzed in detail. Two main DC subsets were identified in seroma that corresponded to the migratory DC subsets present in lymph nodes, that is, CD14(+) and CD1a(+). The latter also included CD1a(bright) Langerhans cells. The two DC subsets appeared to share the same monocytic precursor and to be developmentally related; both of them spontaneously released high levels of TGF-ß and displayed similar T cell-activating and -polarizing properties. In contrast, they differed in the expression of surface molecules, including TLRs; in their phagocytic activity; and in the expression of proteins involved in Ag processing and presentation. It is worth noting that although both subsets were detected in seroma in the postsurgical inflammatory phase, only CD1a(+) DCs migrated via afferent lymph under steady-state conditions. In conclusion, the high numbers of DCs contained in seroma fluids allowed a proper characterization of human DCs migrating via afferent lymph, revealing a continuous stream of DCs from peripheral regions toward SLOs under normal conditions. Moreover, we showed that, in inflammatory conditions, distinct subsets of DCs can migrate to SLOs via afferent lymph.

NK cells from malignant pleural effusions are not anergic but produce cytokines and display strong antitumor activity on short-term IL-2 activation.

NK cells are a major component of innate immunity and exert a potent antitumor effect both in vitro and in vivo. However, NK cells infiltrating solid tumors have been shown to display severely impaired functional capabilities. In this study, we analyzed NK cells present in pleural effusions (PEs) of patients with primary or metastatic tumors of different origin, including mesothelioma and lung, breast, colon, gastric, bladder, and uterus carcinoma. In all instances, freshly isolated PE-NK cells displayed a CD56(bright) phenotype and expressed normal levels of both activating receptors and HLA class I-specific inhibitory receptors. In addition, they rapidly released large amounts of IFN-γ and TNF-α after stimulation. Upon culture in IL-2, they acquired a potent cytolytic activity against both allogeneic and autologous tumor cells. Tumor cell lysis was primarily mediated by NKG2D and NKp30 and partially by NKp46 and DNAM-1, in agreement with the expression of the corresponding ligands on tumor cells. The finding that PE-NK cells are not functionally impaired and that they can efficiently kill tumor cells upon short-term IL-2 activation may offer important clues for the development of novel approaches in tumor immunotherapy.

Long-term in vitro maintenance of plasma cells in a hydrogel-enclosed human bone marrow microphysiological 3D model system.

Plasma cells (PCs) in bone marrow (BM) play an important role in both protective and pathogenic humoral immune responses, e.g., in various malignant and non-malignant diseases such as multiple myeloma (MM), primary and secondary immunodeficiencies and autoimmune diseases. Dedicated microenvironmental niches in the BM provide PCs with biomechanical and soluble factors that support their long-term survival. There is a high need for appropriate and robust model systems to better understand PCs biology, to develop new therapeutic strategies for PCs-related diseases and perform targeted preclinical studies with high predictive value. Most preclinical data have been derived from in vivo studies in mice, as in vitro studies of human PCs are limited due to restricted survival and functionality in conventional 2D cultures that do not reflect the unique niche architecture of the BM. We have developed a microphysiological, dynamic 3D BM culture system (BM-MPS) based on human primary tissue (femoral biopsies), mechanically supported by a hydrogel scaffold casing. While a bioinert agarose casing did not support PCs survival, a photo-crosslinked collagen-hyaluronic acid (Col-HA) hydrogel preserved the native BM niche architecture and allowed PCs survival in vitro for up to 2 weeks. Further, the Col-HA hydrogel was permissive to lymphocyte migration into the microphysiological system´s circulation. Long-term PCs survival was related to the stable presence in the culture of soluble factors, as APRIL, BAFF, and IL-6. Increasing immunoglobulins concentrations in the medium confirm their functionality over culture time. To the best of our knowledge, this study is the first report of successful long-term maintenance of primary-derived non-malignant PCs in vitro. Our innovative model system is suitable for in-depth in vitro studies of human PCs regulation and exploration of targeted therapeutic approaches such as CAR-T cell therapy or biologics.

Nodal Elective Volume Selection and Definition during Radiation Therapy for Early Stage (T1-T2 N0 M0) Perianal Squamous Cell Carcinoma: A Narrative Clinical Review and Critical Appraisal.

Distinction between anal canal and perianal squamous cell carcinomas (pSCCs) is essential, as these two subgroups have different anatomical, histological, and lymphatic drainage features. Early-stage true perianal tumors are very uncommon and have been rarely included in clinical trials. Perianal skin cancers and aCCs are included in the same tumor classification, even though they have different lymphatic drainage features. Furthermore, pSCCs are treated similarly to carcinomas originating from the anal canal. Radiation therapy (RT) is an essential treatment for anal canal tumors. Guidelines do not differentiate between treatment volumes for perianal tumors and anal cancers. So far, in pSCC, no study has considered modulating treatment volume selection according to the stage of the disease. We conducted a narrative literature review to describe the sites at higher risk for microscopic disease in patients with early-stage perianal cancers (T1-T2 N0 M0) to propose a well-thought selection of RT elective volumes.

CAR NK-92 cell-mediated depletion of residual TCR+ cells for ultrapure allogeneic TCR-deleted CAR T-cell products.

Graft-versus-host disease (GVHD) is a major risk of the administration of allogeneic chimeric antigen receptor (CAR)-redirected T cells to patients who are HLA unmatched. Gene editing can be used to disrupt potentially alloreactive T-cell receptors (TCRs) in CAR T cells and reduce the risk of GVHD. Despite the high knockout rates achieved with the optimized methods, a subsequent purification step is necessary to obtain a safe allogeneic product. To date, magnetic cell separation (MACS) has been the gold standard for purifying TCRα/ß- CAR T cells, but product purity can still be insufficient to prevent GVHD. We developed a novel and highly efficient approach to eliminate residual TCR/CD3+ T cells after TCRα constant (TRAC) gene editing by adding a genetically modified CD3-specific CAR NK-92 cell line during ex vivo expansion. Two consecutive cocultures with irradiated, short-lived, CAR NK-92 cells allowed for the production of TCR- CAR T cells with <0.01% TCR+ T cells, marking a 45-fold reduction of TCR+ cells compared with MACS purification. Through an NK-92 cell-mediated feeder effect and circumventing MACS-associated cell loss, our approach increased the total TCR- CAR T-cell yield approximately threefold while retaining cytotoxic activity and a favorable T-cell phenotype. Scaling in a semiclosed G-Rex bioreactor device provides a proof-of-principle for large-batch manufacturing, allowing for an improved cost-per-dose ratio. Overall, this cell-mediated purification method has the potential to advance the production process of safe off-the-shelf CAR T cells for clinical applications.

Combined genotypic and phenotypic killer cell Ig-like receptor analyses reveal KIR2DL3 alleles displaying unexpected monoclonal antibody reactivity: identification of the amino acid residues critical for staining.

In humans, recent clinical and experimental data from hematopoietic stem cell transplantation revealed that donor-derived alloreactive NK cells exert a beneficial graft versus leukemia effect. The existence of donor-derived alloreactive NK cells can be predicted on the basis of donor killer cell Ig-like receptor (KIR) gene profile and HLA class I typing of both donor and recipient. Moreover, the size of the alloreactive NK cell population can be directly assessed by the combined use of anti-KIR-specific mAb. In this study, in an attempt to improve the definition of alloreactive NK cell subsets, we assessed the KIR genotype and phenotype in a cohort of 44 donors. This approach allowed the identification of two different KIR2DL3 alleles (KIR2DL3*005 and the novel allele KIR2DL3*015) that did not react with the anti-KIR2DL3-specific ECM41 mAb. In contrast, both alleles were recognized at the cell surface by several mAb reacting with KIR2DL2/L3/S2. Notably, KIR2DL3*005 was also stained by the anti-KIR2DL1/S1-specific EB6B and 11PB6 mAb. Functional analysis revealed that, despite its particular mAb reactivity, the specificity of KIR2DL3*005 for HLA-C molecules did not differ from that of other KIR2DL2/L3 alleles. Finally, site-directed mutagenesis demonstrated that glutamine at position 35 is required for ECM41 staining, whereas glutamic acid 35 and arginine 50 are relevant for staining with EB6B or 11PB6 mAb. Our present data represent a substantial progress in the characterization of the NK cell repertoire and an improved phenotypic/functional definition of given KIR(+) subsets.

Effect of Eribulin on Angiogenesis and the Expression of Endothelial Adhesion Molecules.

BACKGROUND/AIM: Tumor vasculature is an important component of the tumor microenvironment and deeply affects anticancer immune response. Eribulin is a non-taxane inhibitor of the mitotic spindle. However, off-target effects interfering with the tumor vasculature have been reported. The mechanisms responsible of this effect are still unclear. MATERIALS AND METHODS: We designed an in vitro study to investigate the effect of eribulin, with or without TGF-ß, on neo-angiogenesis, and on the expression of the adhesion molecules ICAM-1 and VCAM-1. We also investigated the effects of paclitaxel and vinorelbine under the same experimental conditions. RESULTS: Eribulin up-regulated the epithelial markers VE-cadherin and CD-31 in HUVEC and inhibited tube formation in HUVEC cells cultured in Matrigel. The drug effectively arrested tube formation even in the presence of TGF-ß and counteracted the TGF-ß-induced change in cell shape from the endothelial cobblestone-like morphology to an elongated spindle-shaped morphology. We also observed that eribulin was able to upregulate ICAM-1 and to counteract its down-regulation induced by TGF-ß. CONCLUSION: Eribulin exerts different off-label effects: increases vascular remodeling, counteracts the endothelial-to-mesenchymal transition (EndMT) mediated by TGF-ß and promotes tumor infiltration by immune cells via increasing the expression of ICAM-1 and transcription of CD31 and VE-cadherin. Moreover, eribulin was able to inhibit vasculature remodeling and the induction of EndMT mediated by TGF-ß better than vinorelbine and paclitaxel. The effects observed in this study might have important therapeutic consequence if the drug is combined with immunotherapy.

Pharmacological interventions enhance virus-free generation of TRAC-replaced CAR T cells.

Chimeric antigen receptor (CAR) redirected T cells are potent therapeutic options against hematological malignancies. The current dominant manufacturing approach for CAR T cells depends on retroviral transduction. With the advent of gene editing, insertion of a CD19-CAR into the T cell receptor (TCR) alpha constant (TRAC) locus using adeno-associated viruses for gene transfer was demonstrated, and these CD19-CAR T cells showed improved functionality over their retrovirally transduced counterparts. However, clinical-grade production of viruses is complex and associated with extensive costs. Here, we optimized a virus-free genome-editing method for efficient CAR insertion into the TRAC locus of primary human T cells via nuclease-assisted homology-directed repair (HDR) using CRISPR-Cas and double-stranded template DNA (dsDNA). We evaluated DNA-sensor inhibition and HDR enhancement as two pharmacological interventions to improve cell viability and relative CAR knockin rates, respectively. While the toxicity of transfected dsDNA was not fully prevented, the combination of both interventions significantly increased CAR knockin rates and CAR T cell yield. Resulting TRAC-replaced CD19-CAR T cells showed antigen-specific cytotoxicity and cytokine production in vitro and slowed leukemia progression in a xenograft mouse model. Amplicon sequencing did not reveal significant indel formation at potential off-target sites with or without exposure to DNA-repair-modulating small molecules. With TRAC-integrated CAR+ T cell frequencies exceeding 50%, this study opens new perspectives to exploit pharmacological interventions to improve non-viral gene editing in T cells.

Anti-leukemia activity of alloreactive NK cells in KIR ligand-mismatched haploidentical HSCT for pediatric patients: evaluation of the functional role of activating KIR and redefinition of inhibitory KIR specificity.

We analyzed 21 children with leukemia receiving haploidentical hematopoietic stem cell transplantation (haplo-HSCT) from killer immunoglobulin (Ig)-like receptors (KIR) ligand-mismatched donors. We showed that, in most transplantation patients, variable proportions of donor-derived alloreactive natural killer (NK) cells displaying anti-leukemia activity were generated and maintained even late after transplantation. This was assessed through analysis of donor KIR genotype, as well as through phenotypic and functional analyses of NK cells, both at the polyclonal and clonal level. Donor-derived KIR2DL1(+) NK cells isolated from the recipient displayed the expected capability of selectively killing C1/C1 target cells, including patient leukemia blasts. Differently, KIR2DL2/3(+) NK cells displayed poor alloreactivity against leukemia cells carrying human leukocyte antigen (HLA) alleles belonging to C2 group. Unexpectedly, this was due to recognition of C2 by KIR2DL2/3, as revealed by receptor blocking experiments and by binding assays of soluble KIR to HLA-C transfectants. Remarkably, however, C2/C2 leukemia blasts were killed by KIR2DL2/3(+) (or by NKG2A(+)) NK cells that coexpressed KIR2DS1. This could be explained by the ability of KIR2DS1 to directly recognize C2 on leukemia cells. A role of the KIR2DS2 activating receptor in leukemia cell lysis could not be demonstrated. Altogether, these results may have important clinical implications for the selection of optimal donors for haplo-HSCT.

Decreasing treatment burden in HPV-related OPSCC: A systematic review of clinical trials.

INTRODUCTION: Favorable outcomes are observed after treatment with standard chemoradiotherapy (CRT) for Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) patients. The consistent growing interest on treatment-related toxicity burden, potentially jeopardizing survivors' quality of life, led clinicians to investigate possible de-escalation strategies. MATERIALS AND METHODS: A comprehensive systematic literature search of clinical trials was performed through the EMBASE database to provide an overview of the de-escalation strategies spectrum. Additionally, hand searching and clinicaltrials.gov were also used. RESULTS: Herein, we report and discuss different approaches to de-escalation of therapy, with respect to both local and systemic strategies. CONCLUSIONS: Several promising de-escalation experiences have been published. However, while further evidence is awaited, no changes in the management nor deviation from the standard of care should be made outside of clinical trials.

IL-27 Mediates PD-L1 Expression and Release by Human Mesothelioma Cells.

Malignant mesothelioma (MM) is a rare tumor with an unfavorable prognosis. MM genesis involves asbestos-mediated local inflammation, supported by several cytokines, including IL-6. Recent data showed that targeting PD-1/PD-L1 is an effective therapy in MM. Here, we investigated the effects of IL-6 trans-signaling and the IL-6-related cytokine IL-27 on human MM cells in vitro by Western blot analysis of STAT1/3 phosphorylation. The effects on PD-L1 expression were tested by qRT-PCR and flow-cytometry and the release of soluble (s)PD-L1 by ELISA. We also measured the concentrations of sPD-L1 and, by multiplexed immunoassay, IL-6 and IL-27 in pleural fluids obtained from 77 patients in relation to survival. IL-27 predominantly mediates STAT1 phosphorylation and increases PD-L1 gene and surface protein expression and sPD-L1 release by human MM cells in vitro. IL-6 has limited activity, whereas a sIL-6R/IL-6 chimeric protein mediates trans-signaling predominantly via STAT3 phosphorylation but has no effect on PD-L1 expression and release. IL-6, IL-27, and sPD-L1 are present in pleural fluids and show a negative correlation with overall survival, but only IL-27 shows a moderate albeit significant correlation with sPD-L1 levels. Altogether these data suggest a potential role of IL-27 in PD-L1-driven immune resistance in MM.

Polymorphonuclear Myeloid-Derived Suppressor Cells Are Abundant in Peripheral Blood of Cancer Patients and Suppress Natural Killer Cell Anti-Tumor Activity.

Tumor microenvironment (TME) includes a wide variety of cell types and soluble factors capable of suppressing immune-responses. While the role of NK cells in TME has been analyzed, limited information is available on the presence and the effect of polymorphonuclear (PMN) myeloid-derived suppressor cells, (MDSC). Among the immunomodulatory cells present in TME, MDSC are potentially efficient in counteracting the anti-tumor activity of several effector cells. We show that PMN-MDSC are present in high numbers in the PB of patients with primary or metastatic lung tumor. Their frequency correlated with the overall survival of patients. In addition, it inversely correlated with low frequencies of NK cells both in the PB and in tumor lesions. Moreover, such NK cells displayed an impaired anti-tumor activity, even those isolated from PB. The compromised function of NK cells was consequent to their interaction with PMN-MDSC. Indeed, we show that the expression of major activating NK receptors, the NK cytolytic activity and the cytokine production were inhibited upon co-culture with PMN-MDSC through both cell-to-cell contact and soluble factors. In this context, we show that exosomes derived from PMN-MDSC are responsible of a significant immunosuppressive effect on NK cell-mediated anti-tumor activity. Our data may provide a novel useful tool to implement the tumor immunoscore. Indeed, the detection of PMN-MDSC in the PB may be of prognostic value, providing clues on the presence and extension of both adult and pediatric tumors and information on the efficacy not only of immune response but also of immunotherapy and, possibly, on the clinical outcome.

Cytokine-Induced Guanylate Binding Protein 1 (GBP1) Release from Human Ovarian Cancer Cells.

We showed that IL-27 shares several effects with IFN-γ in human cancer cells. To identify novel extracellular mediators, potentially involved in epithelial ovarian cancer (EOC) biology, we analyzed the effect of IL-27 or IFN-γ on the secretome of cultured EOC cells by mass-spectrometry (nano-UHPLC-MS/MS). IL-27 and IFN-γ modulate the release of a limited fraction of proteins among those induced in the whole cell. We focused our attention on GBP1, a guanylate-binding protein and GTPase, which mediates several biological activities of IFNs. Cytokine treatment induced GBP1, 2, and 5 expressions in EOC cells, but only GBP1 was secreted. ELISA and immunoblotting showed that cytokine-stimulated EOC cells release full-length GBP1 in vitro, through non-classical pathways, not involving microvesicles. Importantly, full-length GBP1 accumulates in the ascites of most EOC patients and ex-vivo EOC cells show constitutive tyrosine-phosphorylated STAT1/3 proteins and GBP1 expression, supporting a role for Signal Transducer And Activator Of Transcription (STAT)-activating cytokines in vivo. High GBP1 gene expression correlates with better overall survival in the TCGA (The Cancer Genome Atlas) dataset of EOC. In addition, GBP1 transfection partially reduced EOC cell viability in an MTT assay. Our data show for the first time that cytokine-stimulated tumor cells release soluble GBP1 in vitro and in vivo and suggest that GBP1 may have anti-tumor effects in EOC.