Germinal Center Dark Zone harbors ATR-dependent determinants of T-cell exclusion that are also identified in aggressive lymphoma.

The germinal center (GC) dark zone (DZ) and light zone (LZ) regions spatially separate expansion and diversification from selection of antigen-specific B-cells to ensure antibody affinity maturation and B cell memory. The DZ and LZ differ significantly in their immune composition despite the lack of a physical barrier, yet the determinants of this polarization are poorly understood. This study provides novel insights into signals controlling asymmetric T-cell distribution between DZ and LZ regions. We identify spatially-resolved DNA damage response and chromatin compaction molecular features that underlie DZ T-cell exclusion. The DZ spatial transcriptional signature linked to T-cell immune evasion clustered aggressive Diffuse Large B-cell Lymphomas (DLBCL) for differential T cell infiltration. We reveal the dependence of the DZ transcriptional core signature on the ATR kinase and dissect its role in restraining inflammatory responses contributing to establishing an immune-repulsive imprint in DLBCL. These insights may guide ATR-focused treatment strategies bolstering immunotherapy in tumors marked by DZ transcriptional and chromatin-associated features.

ZEB1 shapes AML immunological niches, suppressing CD8 T cell activity while fostering Th17 cell expansion.

Acute myeloid leukemia (AML) progression is influenced by immune suppression induced by leukemia cells. ZEB1, a critical transcription factor in epithelial-to-mesenchymal transition, demonstrates immune regulatory functions in AML. Silencing ZEB1 in leukemic cells reduces engraftment and extramedullary disease in immune-competent mice, activating CD8 T lymphocytes and limiting Th17 cell expansion. ZEB1 in AML cells directly promotes Th17 cell development that, in turn, creates a self-sustaining loop and a pro-invasive phenotype, favoring transforming growth factor ß (TGF-ß), interleukin-23 (IL-23), and SOCS2 gene transcription. In bone marrow biopsies from AML patients, immunohistochemistry shows a direct correlation between ZEB1 and Th17. Also, the analysis of ZEB1 expression in larger datasets identifies two distinct AML groups, ZEB1high and ZEB1low, each with specific immunological and molecular traits. ZEB1high patients exhibit increased IL-17, SOCS2, and TGF-ß pathways and a negative association with overall survival. This unveils ZEB1's dual role in AML, entwining pro-tumoral and immune regulatory capacities in AML blasts.

APOLLO 11 Project, Consortium in Advanced Lung Cancer Patients Treated With Innovative Therapies: Integration of Real-World Data and Translational Research.

INTRODUCTION: Despite several therapeutic efforts, lung cancer remains a highly lethal disease. Novel therapeutic approaches encompass immune-checkpoint inhibitors, targeted therapeutics and antibody-drug conjugates, with different results. Several studies have been aimed at identifying biomarkers able to predict benefit from these therapies and create a prediction model of response, despite this there is a lack of information to help clinicians in the choice of therapy for lung cancer patients with advanced disease. This is primarily due to the complexity of lung cancer biology, where a single or few biomarkers are not sufficient to provide enough predictive capability to explain biologic differences; other reasons include the paucity of data collected by single studies performed in heterogeneous unmatched cohorts and the methodology of analysis. In fact, classical statistical methods are unable to analyze and integrate the magnitude of information from multiple biological and clinical sources (eg, genomics, transcriptomics, and radiomics). METHODS AND OBJECTIVES: APOLLO11 is an Italian multicentre, observational study involving patients with a diagnosis of advanced lung cancer (NSCLC and SCLC) treated with innovative therapies. Retrospective and prospective collection of multiomic data, such as tissue- (eg, for genomic, transcriptomic analysis) and blood-based biologic material (eg, ctDNA, PBMC), in addition to clinical and radiological data (eg, for radiomic analysis) will be collected. The overall aim of the project is to build a consortium integrating different datasets and a virtual biobank from participating Italian lung cancer centers. To face with the large amount of data provided, AI and ML techniques will be applied will be applied to manage this large dataset in an effort to build an R-Model, integrating retrospective and prospective population-based data. The ultimate goal is to create a tool able to help physicians and patients to make treatment decisions. CONCLUSION: APOLLO11 aims to propose a breakthrough approach in lung cancer research, replacing the old, monocentric viewpoint towards a multicomprehensive, multiomic, multicenter model. Multicenter cancer datasets incorporating common virtual biobank and new methodologic approaches including artificial intelligence, machine learning up to deep learning is the road to the future in oncology launched by this project.

High bone tumor burden to identify advanced non-small cell lung cancer patients with survival benefit upon bone targeted agents and immune checkpoint inhibitors.

BACKGROUND: Bone-targeted agents (BTA), such as denosumab (DN) and zoledronic acid (ZA), have historically reduced the risk of skeletal related events in cancer patients with bone metastases (BM), with no improvement in survival outcomes. In the immunotherapy era, BM have been associated with poor prognosis upon immune-checkpoint inhibitors (ICI). Currently, the impact of bone tumor burden on survival upon BTAs in advanced non-small cell lung cancer (aNSCLC) patients treated with ICI remains unknown. METHODS: Data from ICI-treated aNSCLC patients with BM (4/2013-5/2022) in one institution were retrospectively collected. BTA-ICI concurrent treatment was defined as BTA administration at any time before or within 90 days from ICI start. High bone tumor burden (HBTB) was defined as ≥ 3 sites of BM. Median OS (mOS) was estimated with Kaplan-Meier. Aikaike's information criterion (AIC) was used to select the best model for data analysis adjusted for clinical variables. RESULTS: Of 134 patients included, 51 (38 %) received BTA. At a mFU of 39.6 months (m), BTA-ICIs concurrent treatment did not significantly impact on mOS [8.3 m (95% CI 3.9-12.8) versus (vs) 6.8 m (95% CI 4.0-9.6) p = 0.36]; these results were confirmed after adjustment for clinical variables selected by AIC. A multivariate model showed a significant interaction between BTA use and HBTB or radiation therapy to BM. In subgroup analyses, only HBTB confirmed to be associated with significantly longer mOS [8.3 m (95% CI 2.4-14.2) vs 3.5 m (95% CI 2.9-4.1), p = 0.003] and mPFS [3.0 m (95% CI 1.6-4.4) vs 1.8 m (95% CI 1.6-2.0) p = 0.001] upon BTA-ICI concurrent treatment, with the most pronounced OS benefit observed for DN-ICI concurrent regimen [15.2 m (95% CI 0.1-30.7) vs 3.5 m (95% CI 2.9-4.1) p = 0.002]. CONCLUSIONS: In the immunotherapy era, HBTB can identify patients experiencing survival benefit with BTA, especially with DN-ICI combination. HBTB should be included as a stratification factor in the upcoming trials assessing BTA and ICI combinations in patients with aNSCLC and BM.

Extracellular nicotinamide phosphoribosyltransferase (eNAMPT) neutralization counteracts T cell immune evasion in breast cancer.

BACKGROUND: Nicotinamide phosphoribosyltransferase (NAMPT) is a key intracellular enzyme that participates in nicotinamide adenine dinucleotide (NAD) homeostasis as well as a released cytokine (eNAMPT) that is elevated in inflammatory conditions and in cancer. In patients with breast cancer, circulating eNAMPT is elevated and its plasma levels correlate with prognosis and staging. In light of this, we investigated the contribution of eNAMPT in triple negative mammary carcinoma progression by investigating the effect of its neutralization via a specific neutralizing monoclonal antibody (C269). METHODS: We used female BALB/c mice injected with 4T1 clone 5 cells and female C57BL6 injected with EO771 cells, evaluating tumoral size, spleen weight and number of metastases. We injected two times a week the anti-eNAMPT neutralizing antibody and we sacrificed the mice after 28 days. Harvested tumors were analyzed by histopathology, flow cytometry, western blot, immunohistochemistry, immunofluorescence and RNA sequencing to define tumor characteristics (isolating tumor infiltrating lymphocytes and tumoral cells) and to investigate the molecular mechanisms behind the observed phenotype. Moreover, we dissected the functional relationship between T cells and tumoral cells using three-dimensional (3D) co-cultures. RESULTS: The neutralization of eNAMPT with C269 led to decreased tumor size and reduced number of lung metastases. RNA sequencing and functional assays showed that eNAMPT controlled T-cell response via the programmed death-ligand 1/programmed cell death protein 1 (PD-L1/PD-1) axis and its neutralization led to a restoration of antitumoral immune responses. In particular, eNAMPT neutralization was able to activate CD8+IFNγ+GrzB+ T cells, reducing the immunosuppressive phenotype of T regulatory cells. CONCLUSIONS: These studies indicate for the first time eNAMPT as a novel immunotherapeutic target for triple negative breast cancer.

The EU-funded I3LUNG Project: Integrative Science, Intelligent Data Platform for Individualized LUNG Cancer Care With Immunotherapy.

Although immunotherapy (IO) has changed the paradigm for the treatment of patients with advanced non-small cell lung cancers (aNSCLC), only around 30% to 50% of treated patients experience a long-term benefit from IO. Furthermore, the identification of the 30 to 50% of patients who respond remains a major challenge, as programmed Death-Ligand 1 (PD-L1) is currently the only biomarker used to predict the outcome of IO in NSCLC patients despite its limited efficacy. Considering the dynamic complexity of the immune system-tumor microenvironment (TME) and its interaction with the host's and patient's behavior, it is unlikely that a single biomarker will accurately predict a patient's outcomes. In this scenario, Artificial Intelligence (AI) and Machine Learning (ML) are becoming essential to the development of powerful decision-making tools that are able to deal with this high-complexity and provide individualized predictions to better match treatments to individual patients and thus improve patient outcomes and reduce the economic burden of aNSCLC on healthcare systems. I3LUNG is an international, multicenter, retrospective and prospective, observational study of patients with aNSCLC treated with IO, entirely funded by European Union (EU) under the Horizon 2020 (H2020) program. Using AI-based tools, the aim of this study is to promote individualized treatment in aNSCLC, with the goals of improving survival and quality of life, minimizing or preventing undue toxicity and promoting efficient resource allocation. The final objective of the project is the construction of a novel, integrated, AI-assisted data storage and elaboration platform to guide IO administration in aNSCLC, ensuring easy access and cost-effective use by healthcare providers and patients.

ATF3 Reprograms the Bone Marrow Niche in Response to Early Breast Cancer Transformation.

Cancer is a systemic disease able to reprogram the bone marrow (BM) niche towards a protumorigenic state. The impact of cancer on specific BM subpopulations can qualitatively differ according to the signals released by the tumor, which can vary on the basis of the tissue of origin. Using a spontaneous model of mammary carcinoma, we identified BM mesenchymal stem cells (MSC) as the first sensors of distal cancer cells and key mediators of BM reprogramming. Through the release of IL1B, BM MSCs induced transcriptional upregulation and nuclear translocation of the activating transcription factor 3 (ATF3) in hematopoietic stem cells. ATF3 in turn promoted the formation of myeloid progenitor clusters and sustained myeloid cell differentiation. Deletion of Atf3 specifically in the myeloid compartment reduced circulating monocytes and blocked their differentiation into tumor-associated macrophages. In the peripheral blood, the association of ATF3 expression in CD14+ mononuclear cells with the expansion CD11b+ population was able to discriminate between women with malignant or benign conditions at early diagnosis. Overall, this study identifies the IL1B/ATF3 signaling pathway in the BM as a functional step toward the establishment of a tumor-promoting emergency myelopoiesis, suggesting that ATF3 could be tested in a clinical setting as a circulating marker of early transformation and offering the rationale for testing the therapeutic benefits of IL1B inhibition in patients with breast cancer. Significance: Bone marrow mesenchymal stem cells respond to early breast tumorigenesis by upregulating IL1B to promote ATF3 expression in hematopoietic stem cells and to induce myeloid cell differentiation that supports tumor development.

Intracellular osteopontin protects from autoimmunity-driven lymphoma development inhibiting TLR9-MYD88-STAT3 signaling.

BACKGROUND: Autoimmune disorders, including Systemic Lupus Erythematosus (SLE), are associated with increased incidence of hematological malignancies. The matricellular protein osteopontin (OPN) has been linked to SLE pathogenesis, as SLE patients show increased serum levels of OPN and often polymorphisms in its gene. Although widely studied for its pro-tumorigenic role in different solid tumours, the role of OPN in autoimmunity-driven lymphomagenesis has not been investigated yet. METHODS: To test the role of OPN in the SLE-associated lymphomagenesis, the SLE-like prone Faslpr/lpr mutation was transferred onto an OPN-deficient background. Spleen from Faslpr/lpr and OPN-/-Faslpr/lpr mice, as well as purified B cells, were analysed by histopathology, flow cytometry, Western Blot, immunohistochemistry, immunofluorescence and gene expression profile to define lymphoma characteristics and investigate the molecular mechanisms behind the observed phenotype. OPN cellular localization in primary splenic B cells and mouse and human DLBCL cell lines was assessed by confocal microscopy. Finally, gain of function experiments, by stable over-expression of the secreted (sOPN) and intracellular OPN (iOPN) in OPN-/-Faslpr/lpr -derived DLBCL cell lines, were performed for further validation experiments. RESULTS: Despite reduced autoimmunity signs, OPN-/-Faslpr/lpr mice developed splenic lymphomas with higher incidence than Faslpr/lpr counterparts. In situ and ex vivo analysis featured such tumours as activated type of diffuse large B cell lymphoma (ABC-DLBCL), expressing BCL2 and c-MYC, but not BCL6, with activated STAT3 signaling. OPN-/-Faslpr/lpr B lymphocytes showed an enhanced TLR9-MYD88 signaling pathway, either at baseline or after stimulation with CpG oligonucleotides, which mimic dsDNA circulating in autoimmune conditions. B cells from Faslpr/lpr mice were found to express the intracellular form of OPN. Accordingly, gene transfer-mediated re-expression of iOPN, but not of its secreted isoform, into ABC-DLBCL cell lines established from OPN-/-Faslpr/lpr mice, prevented CpG-mediated activation of STAT3, suggesting that the intracellular form of OPN may represent a brake to TLR9 signaling pathway activation. CONCLUSION: These data indicate that, in the setting of SLE-like syndrome in which double strand-DNA chronically circulates and activates TLRs, B cell intracellular OPN exerts a protective role in autoimmunity-driven DLBCL development, mainly acting as a brake in the TLR9-MYD88-STAT3 signaling pathway.

Circulating Fatty Acid Profile as a Biomarker for Immunotherapy in Advanced Non-Small Cell Lung Cancer.

INTRODUCTION: Lipid metabolism impacts immune cell differentiation, activation, and functions, modulating inflammatory mediators, energy homeostasis, and cell membrane composition. Despite preclinical evidence, data in humans lack concerning tumors and immunotherapy (IO). We aimed at investigating the correlations between circulating lipids and the outcome of non-small cell lung cancer (NSCLC) patients treated with IO. MATERIALS AND METHODS: We identified all patients with advanced NSCLC treated with IO at our Institution with available baseline plasma samples. Fatty acids (FAs) were analyzed through gas chromatography. Survival curves were estimated by the Kaplan-Meier method. Cox multivariate models were constructed through a stepwise procedure, with entry and exit P value set at .2. RESULTS: We identified 112 patients, mostly with performance status 1 (65.2%) and PD-L1≥1% (75.3%). Median progression-free survival (PFS) and overall survival (OS) were 2.8 and 11.0 months, respectively. Multivariable model for survival identified a positive association of circulating free (FFA) C16:0 (P .005) and esterified (EFA) C16:1 (P .030) with PFS, and a positive association of EFA C16:1 (P .001) and EFA C18:0 (P .020) with OS. EFA C16:0 was negatively associated with PFS (P .008). CONCLUSION: FFA C16:0 and FAs derived from its unsaturation (EFA C16:1) and elongation (EFA C18:0) are associated with a better outcome in NSCLC patients treated with IO. It is conceivable that the ratio among those FAs may modify membrane fluidity and receptor activity, influencing IO efficacy. These data pave the way for the investigation of lipid-modulating strategies in association with IO in NSCLC.

SCD5-dependent inhibition of SPARC secretion hampers metastatic spreading and favors host immunity in a TNBC murine model.

Dysregulated fatty acid metabolism interacts with oncogenic signals, thereby worsening tumor aggressiveness. The stearoyl-CoA desaturating enzymes, SCD1 and SCD5, convert of saturated fatty acids to monounsaturated fatty acids. While SCD1 is frequently overexpressed in tumor cells and has been widely studied, SCD5 has both limited expression and poor characterization. Here we evaluated, in vitro and in vivo, the effects of SCD5 overexpression in a metastatic clone of 4T1. The results showed SCD5-driven reprogramming of fatty acid metabolism, involving desaturation of stearic acid to oleic acid, which eventually blocked SPARC secretion. The latter event reduced the aggressiveness of the 4T1 subclone by decreasing the ECM deposition and reverting the Epithelial to Mesenchymal Transition (EMT) status. Variation of the fatty acid profile by SCD5-gene transduction or the direct administration oleic acid reduces the immune suppressive activity of myeloid cells and promoting granulocytic myeloid-derived suppressor cell maturation, eventually favoring T-cell activation. The less immunosuppressive microenvironment generated by SCD5 overexpression was enhanced in Sparc-KO mice, indicating that both extracellular and endogenous SPARC additively regulate myeloid cell-suppressive activities. Overall, our data sheds light on exploring the oleic acid-dependent inhibition of SPARC secretion as a possible mechanism to reduce breast cancer malignancy.

CIC-39Na reverses the thrombocytopenia that characterizes tubular aggregate myopathy.

Store-operated Ca2+-entry is a cellular mechanism that governs the replenishment of intracellular stores of Ca2+ upon depletion caused by the opening of intracellular Ca2+-channels. Gain-of-function mutations of the 2 key proteins of store-operated Ca2+-entry, STIM1 and ORAI1, are associated with several ultra-rare diseases clustered as tubular aggregate myopathies. Our group has previously demonstrated that a mouse model bearing the STIM1 p.I115F mutation recapitulates the main features of the STIM1 gain-of-function disorders: muscle weakness and thrombocytopenia. Similar findings have been found in other mice bearing different mutations on STIM1. At present, no valid treatment is available for these patients. In the present contribution, we report that CIC-39Na, a store-operated Ca2+-entry inhibitor, restores platelet number and counteracts the abnormal bleeding that characterizes these mice. Subtle differences in thrombopoiesis were observed in STIM1 p.I115F mice, but the main difference between wild-type and STIM1 p.I115F mice was in platelet clearance and in the levels of platelet cytosolic basal Ca2+. Both were restored on treatment of animals with CIC-39Na. This finding paves the way to a pharmacological treatment strategy for thrombocytopenia in tubular aggregate myopathy patients.

Neutrophil extracellular traps arm DC vaccination against NPM-mutant myeloproliferation.

Neutrophil extracellular traps (NETs) are web-like chromatin structures composed by dsDNA and histones, decorated with antimicrobial proteins. Their interaction with dendritic cells (DCs) allows DC activation and maturation toward presentation of NET-associated antigens. Differently from other types of cell death that imply protein denaturation, NETosis preserves the proteins localized onto the DNA threads for proper enzymatic activity and conformational status, including immunogenic epitopes. Besides neutrophils, leukemic cells can release extracellular traps displaying leukemia-associated antigens, prototypically mutant nucleophosmin (NPMc+) that upon mutation translocates from nucleolus to the cytoplasm localizing onto NET threads. We tested NPMc+ immunogenicity through a NET/DC vaccine to treat NPMc-driven myeloproliferation in transgenic and transplantable models. Vaccination with DC loaded with NPMc+ NET (NPMc+ NET/DC) reduced myeloproliferation in transgenic mice, favoring the development of antibodies to mutant NPMc and the induction of a CD8+ T-cell response. The efficacy of this vaccine was also tested in mixed NPMc/WT bone marrow (BM) chimeras in a competitive BM transplantation setting, where the NPMc+ NET/DC vaccination impaired the expansion of NPMc+ in favor of WT myeloid compartment. NPMc+ NET/DC vaccination also achieved control of an aggressive leukemia transduced with mutant NPMc, effectively inducing an antileukemia CD8 T-cell memory response.

Release of IFNγ by Acute Myeloid Leukemia Cells Remodels Bone Marrow Immune Microenvironment by Inducing Regulatory T Cells.

PURPOSE: The stromal and immune bone marrow (BM) landscape is emerging as a crucial determinant for acute myeloid leukemia (AML). Regulatory T cells (Treg) are enriched in the AML microenvironment, but the underlying mechanisms are poorly elucidated. Here, we addressed the effect of IFNγ released by AML cells in BM Treg induction and its impact on AML prognosis. EXPERIMENTAL DESIGN: BM aspirates from patients with AML were subdivided according to IFNG expression. Gene expression profiles in INFγhigh and IFNγlow samples were compared by microarray and NanoString analysis and used to compute a prognostic index. The IFNγ release effect on the BM microenvironment was investigated in mesenchymal stromal cell (MSC)/AML cell cocultures. In mice, AML cells silenced for ifng expression were injected intrabone. RESULTS: IFNγhigh AML samples showed an upregulation of inflammatory genes, usually correlated with a good prognosis in cancer. In contrast, in patients with AML, high IFNG expression was associated with poor overall survival. Notably, IFNγ release by AML cells positively correlated with a higher BM suppressive Treg frequency. In coculture experiments, IFNγhigh AML cells modified MSC transcriptome by upregulating IFNγ-dependent genes related to Treg induction, including indoleamine 2,3-dioxygenase 1 (IDO1). IDO1 inhibitor abrogated the effect of IFNγ release by AML cells on MSC-derived Treg induction. In vivo, the genetic ablation of IFNγ production by AML cells reduced MSC IDO1 expression and Treg infiltration, hindering AML engraftment. CONCLUSIONS: IFNγ release by AML cells induces an immune-regulatory program in MSCs and remodels BM immunologic landscape toward Treg induction, contributing to an immunotolerant microenvironment. See related commentary by Ferrell and Kordasti, p. 2986.

Impact of Immune Cell Heterogeneity on HER2+ Breast Cancer Prognosis and Response to Therapy.

Breast cancer is a heterogeneous disease with a high degree of diversity among and within tumors, and in relation to its different tumor microenvironment. Compared to other oncotypes, such as melanoma or lung cancer, breast cancer is considered a "cold" tumor, characterized by low T lymphocyte infiltration and low tumor mutational burden. However, more recent evidence argues against this idea and indicates that, at least for specific molecular breast cancer subtypes, the immune infiltrate may be clinically relevant and heterogeneous, with significant variations in its stromal cell/protein composition across patients and tumor stages. High numbers of tumor-infiltrating T cells are most frequent in HER2-positive and basal-like molecular subtypes and are generally associated with a good prognosis and response to therapies. However, effector immune infiltrates show protective immunity in some cancers but not in others. This could depend on one or more immunosuppressive mechanisms acting alone or in concert. Some of them might include, in addition to immune cells, other tumor microenvironment determinants such as the extracellular matrix composition and stiffness as well as stromal cells, like fibroblasts and adipocytes, that may prevent cytotoxic T cells from infiltrating the tumor microenvironment or may inactivate their antitumor functions. This review will summarize the state of the different immune tumor microenvironment determinants affecting HER2+ breast tumor progression, their response to treatment, and how they are modified by different therapeutic approaches. Potential targets within the immune tumor microenvironment will also be discussed.

CD40 Activity on Mesenchymal Cells Negatively Regulates OX40L to Maintain Bone Marrow Immune Homeostasis Under Stress Conditions.

Background: Within the bone marrow (BM), mature T cells are maintained under homeostatic conditions to facilitate proper hematopoietic development. This homeostasis depends upon a peculiar elevated frequency of regulatory T cells (Tregs) and immune regulatory activities from BM-mesenchymal stem cells (BM-MSCs). In response to BM transplantation (BMT), the conditioning regimen exposes the BM to a dramatic induction of inflammatory cytokines and causes an unbalanced T-effector (Teff) and Treg ratio. This imbalance negatively impacts hematopoiesis, particularly in regard to B-cell lymphopoiesis that requires an intact cross-talk between BM-MSCs and Tregs. The mechanisms underlying the ability of BM-MSCs to restore Treg homeostasis and proper B-cell development are currently unknown. Methods: We studied the role of host radio-resistant cell-derived CD40 in restoring Teff/Treg homeostasis and proper B-cell development in a murine model of BMT. We characterized the host cellular source of CD40 and performed radiation chimera analyses by transplanting WT or Cd40-KO with WT BM in the presence of T-reg and co-infusing WT or - Cd40-KO BM-MSCs. Residual host and donor T cell expansion and activation (cytokine production) and also the expression of Treg fitness markers and conversion to Th17 were analyzed. The presence of Cd40+ BM-MSCs was analyzed in a human setting in correlation with the frequency of B-cell precursors in patients who underwent HSCT and variably developed acute graft-versus-host (aGVDH) disease. Results: CD40 expression is nearly undetectable in the BM, yet a Cd40-KO recipient of WT donor chimera exhibited impaired B-cell lymphopoiesis and Treg development. Lethal irradiation promotes CD40 and OX40L expression in radio-resistant BM-MSCs through the induction of pro-inflammatory cytokines. OX40L favors Teff expansion and activation at the expense of Tregs; however, the expression of CD40 dampens OX40L expression and restores Treg homeostasis, thus facilitating proper B-cell development. Indeed, in contrast to dendritic cells in secondary lymphoid organs that require CD40 triggers to express OX40L, BM-MSCs require CD40 to inhibit OX40L expression. Conclusions: CD40+ BM-MSCs are immune regulatory elements within BM. Loss of CD40 results in uncontrolled T cell activation due to a reduced number of Tregs, and B-cell development is consequently impaired. GVHD provides an example of how a loss of CD40+ BM-MSCs and a reduction in B-cell precursors may occur in a human setting.

SPARC regulation of PMN clearance protects from pristane-induced lupus and rheumatoid arthritis.

The secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein with unexpected immunosuppressive function in myeloid cells. We investigated the role of SPARC in autoimmunity using the pristane-induced model of lupus that, in mice, mimics human systemic lupus erythematosus (SLE). Sparc -/- mice developed earlier and more severe renal disease, multi-organ parenchymal damage, and arthritis than the wild-type counterpart. Sparc +/- heterozygous mice showed an intermediate phenotype suggesting Sparc gene dosage in autoimmune-related events. Mechanistically, reduced Sparc expression in neutrophils blocks their clearance by macrophages, through defective delivery of don't-eat-me signals. Dying Sparc -/- neutrophils that escape macrophage scavenging become source of autoantigens for dendritic cell presentation and are a direct stimulation for γδT cells. Gene profile analysis of knee synovial biopsies from SLE-associated arthritis showed an inverse correlation between SPARC and key autoimmune genes. These results point to SPARC down-regulation as a leading event characterizing SLE and rheumatoid arthritis pathogenesis.

T Cells Expressing Receptor Recombination/Revision Machinery Are Detected in the Tumor Microenvironment and Expanded in Genomically Over-unstable Models.

Tumors undergo dynamic immunoediting as part of a process that balances immunologic sensing of emerging neoantigens and evasion from immune responses. Tumor-infiltrating lymphocytes (TIL) comprise heterogeneous subsets of peripheral T cells characterized by diverse functional differentiation states and dependence on T-cell receptor (TCR) specificity gained through recombination events during their development. We hypothesized that within the tumor microenvironment (TME), an antigenic milieu and immunologic interface, tumor-infiltrating peripheral T cells could reexpress key elements of the TCR recombination machinery, namely, Rag1 and Rag2 recombinases and Tdt polymerase, as a potential mechanism involved in the revision of TCR specificity. Using two syngeneic invasive breast cancer transplantable models, 4T1 and TS/A, we observed that Rag1, Rag2, and Dntt in situ mRNA expression characterized rare tumor-infiltrating T cells. In situ expression of the transcripts was increased in coisogenic Mlh1-deficient tumors, characterized by genomic overinstability, and was also modulated by PD-1 immune-checkpoint blockade. Through immunolocalization and mRNA hybridization analyses, we detected the presence of rare TDT+RAG1/2+ cells populating primary tumors and draining lymph nodes in human invasive breast cancer. Analysis of harmonized single-cell RNA-sequencing data sets of human cancers identified a very small fraction of tumor-associated T cells, characterized by the expression of recombination/revision machinery transcripts, which on pseudotemporal ordering corresponded to differentiated effector T cells. We offer thought-provoking evidence of a TIL microniche marked by rare transcripts involved in TCR shaping.

Myeloid cell heterogeneity in lung cancer: implication for immunotherapy.

Lung is a specialized tissue where metastases from primary lung tumors takeoff and those originating from extra-pulmonary sites land. One commonality characterizing these processes is the supportive role exerted by myeloid cells, particularly neutrophils, whose recruitment is facilitated in this tissue microenvironment. Indeed, neutrophils have important part in the pathophysiology of this organ and the key mechanisms regulating neutrophil expansion and recruitment during infection can be co-opted by tumor cells to promote growth and metastasis. Although neutrophils dominate the myeloid landscape of lung cancer other populations including macrophages, dendritic cells, mast cells, basophils and eosinophils contribute to the complexity of lung cancer TME. In this review, we discuss the origin and significance of myeloid cells heterogeneity in lung cancer, which translates not only in a different frequency of immune populations but it encompasses state of activation, morphology, localization and mutual interactions. The relevance of such heterogeneity is considered in the context of tumor growth and response to immunotherapy.

Modulation of PD-1/PD-L1 axis in myeloid-derived suppressor cells by anti-cancer treatments.

Immuno checkpoint blockade (ICB) targeting the PD-1/PD-L1 axis is the main breakthrough for the treatment of several cancers. Nevertheless, not all patients benefit from this treatment and clinical response not always correlates with PD-L1 expression by tumor cells. The tumor microenvironment, including myeloid derived suppressor cells (MDSCs), can influence therapeutic resistance to ICB. MDSCs also express PD-L1, which contributes to their suppressive activity. Moreover, anticancer therapies including chemotherapy, radiotherapy, hormone- and targeted- therapies can modulate MDSCs recruitment, activity and PD-L1 expression. Such effects can be induced also by innovative anticancer treatments targeting metabolism and lifestyle. The outcome on cancer progression can be either positive or negative, depending on tumor type, treatment schedule and possible combination with ICB. Further studies are needed to better understand the effects of cancer therapies on the PD-1/PD-L1 axis, to identify patients that could benefit from combinatorial regimens including ICB or that rather should avoid it.