Spatial Transcriptomics Reveal Pitfalls and Opportunities for the Detection of Rare High-Plasticity Breast Cancer Subtypes.

Breast cancer is one of the most prominent types of cancers, in which therapeutic resistance is a major clinical concern. Specific subtypes, such as claudin-low and metaplastic breast carcinoma (MpBC), have been associated with high nongenetic plasticity, which can facilitate resistance. The similarities and differences between these orthogonal subtypes, identified by molecular and histopathological analyses, respectively, remain insufficiently characterized. Furthermore, adequate methods to identify high-plasticity tumors to better anticipate resistance are lacking. Here, we analyzed 11 triple-negative breast tumors, including 3 claudin-low and 4 MpBC, via high-resolution spatial transcriptomics. We combined pathological annotations and deconvolution approaches to precisely identify tumor spots, on which we performed signature enrichment, differential expression, and copy number analyses. We used The Cancer Genome Atlas and Cancer Cell Line Encyclopedia public databases for external validation of expression markers. By focusing our spatial transcriptomic analyses on tumor cells in MpBC samples, we bypassed the negative impact of stromal contamination and identified specific markers that are neither expressed in other breast cancer subtypes nor expressed in stromal cells. Three markers (BMPER, POPDC3, and SH3RF3) were validated in external expression databases encompassing bulk tumor material and stroma-free cell lines. We unveiled that existing bulk expression signatures of high-plasticity breast cancers are relevant in mesenchymal transdifferentiated compartments but can be hindered by abundant stromal cells in tumor samples, negatively impacting their clinical applicability. Spatial transcriptomic analyses constitute powerful tools to identify specific expression markers and could thus enhance diagnosis and clinical care of rare high-plasticity breast cancers.

Gene signature of circulating platelet-bound neutrophils is associated with poor prognosis in cancer patients.

Beyond their critical role in hemostasis, platelets physically interact with neutrophils to form neutrophil-platelet aggregates (NPAs), enhancing neutrophil effector functions during inflammation. NPAs may also promote disease worsening in various inflammatory diseases. However, characterization of NPAs in cancer remains totally unexplored. Using ImageStreamX (ISX) imaging flow cytometer, we were not only allowed able to detect CD15+ CD14- CD36+ ITGA2B+ NPAs in both healthy donors' (HDs) and cancer patients' bloods, but we also showed that NPAs result from the binding of platelets preferentially to low-density neutrophils (LDNs) as opposed to normal-density neutrophils (NDNs). By reanalyzing two independent public scRNAseq data of whole blood leukocytes from cancer patients and HDs, we could identify a subset of neutrophils with high platelet gene expression that may correspond to NPAs. Moreover, we showed that cancer patients' derived NPAs possessed a distinct molecular signature compared to the other neutrophil subsets, independently of platelet genes. Gene ontology (GO) term enrichment analysis of this NPAs-associated neutrophil transcriptomic signature revealed a significant enrichment of neutrophil degranulation, chemotaxis and trans-endothelial migration GO terms. Lastly, using The Cancer Genome Atlas (TCGA), we could show by multivariate Cox analysis that the NPAs-associated neutrophil transcriptomic signature was associated with a worse patient prognosis in several cancer types. These results suggest that neutrophils from NPAs are systemically primed by platelets empowering them with cancer progression capacities once at tumor site. NPAs may therefore hold clinical utility as novel noninvasive blood prognostic biomarker in cancer patients with solid tumors.

HERVs characterize normal and leukemia stem cells and represent a source of shared epitopes for cancer immunotherapy.

Human endogenous retroviruses (HERVs) represent 8% of the human genome. The expression of HERVs and their immune impact have not been extensively studied in Acute Myeloid Leukemia (AML). In this study, we used a reference of 14 968 HERV functional units to provide a thorough analysis of HERV expression in normal and AML bone marrow cells. We show that the HERV retrotranscriptome accurately characterizes normal and leukemic cell subpopulations, including leukemia stem cells, in line with different epigenetic profiles. We then show that HERV expression delineates AML subtypes with different prognoses. We finally propose a method to select and prioritize CD8+ T cell epitopes derived from AML-specific HERVs and we show that lymphocytes infiltrating patient bone marrow at diagnosis contain naturally occurring CD8+ T cells against these HERV epitopes. We also provide in vitro data supporting the functionality of HERV-specific CD8+ T-cells against AML cells. These results show that HERVs represent an important source of genetic information that can help enhancing disease stratification or biomarker identification and an important reservoir of alternative tumor-specific T cell epitopes relevant for cancer immunotherapy.

MAVS deficiency induces gut dysbiotic microbiota conferring a proallergic phenotype.

Prominent changes in the gut microbiota (referred to as "dysbiosis") play a key role in the development of allergic disorders, but the underlying mechanisms remain unknown. Study of the delayed-type hypersensitivity (DTH) response in mice contributed to our knowledge of the pathophysiology of human allergic contact dermatitis. Here we report a negative regulatory role of the RIG-I-like receptor adaptor mitochondrial antiviral signaling (MAVS) on DTH by modulating gut bacterial ecology. Cohousing and fecal transplantation experiments revealed that the dysbiotic microbiota of Mavs-/- mice conferred a proallergic phenotype that is communicable to wild-type mice. DTH sensitization coincided with increased intestinal permeability and bacterial translocation within lymphoid organs that enhanced DTH severity. Collectively, we unveiled an unexpected impact of RIG-I-like signaling on the gut microbiota with consequences on allergic skin disease outcome. Primarily, these data indicate that manipulating the gut microbiota may help in the development of therapeutic strategies for the treatment of human allergic skin pathologies.

Association between FGFR1 copy numbers, MAP3K1 mutations, and survival in axillary node-positive, hormone receptor-positive, and HER2-negative early breast cancer in the PACS04 and METABRIC studies.

PURPOSE: Hormone receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) early breast cancer (BC) is the most prevalent BC subtype with substantial biological heterogeneity. Although clinicopathological (CP) characteristics have a clear prognostic value, additional biomarkers could refine survival prediction and guide treatment decision. METHODS: Copy number aberrations and somatic driver mutations were obtained with OncoScan CGH array and sequencing of 36 genes on HR+/HER2- node-positive early BC patients treated with chemotherapy from the PACS04 trial. We built a two-gene genomic score (GS) associated with distant disease-free survival (DDFS), whose prognostic value was assessed on the external METABRIC data (n = 1413) using overall survival (OS) and breast cancer-specific survival (BCSS). RESULTS: In the PACS04 trial (n = 327), the median follow-up for DDFS (65 events) was 9.6 years. FGFR1 amplifications ([Formula: see text] = 2.44, 95% CI [1.25; 4.76], p = 0.009) and MAP3K1 mutations ([Formula: see text] = 0.10, [0.01; 0.78], p = 0.03) were associated with DDFS beyond CP characteristics. A prognostic GS combining FGFR1 amplifications and MAP3K1 mutations added more information to CP model ([Formula: see text] = 12.97, [Formula: see text] < 0.001 and [Formula: see text] = 11.52, [Formula: see text] < 0.001). In the METABRIC study (n = 1413), FGFR1 amplifications ([Formula: see text] = 2.00 [1.40; 2.87], p < 0.001) and MAP3K1 mutations ([Formula: see text] = 0.58 [0.41; 0.83], p = 0.003) were significantly associated with BCSS beyond CP characteristics. The prognostic GS added significant prognostic information to CP model ([Formula: see text] = 15.39, [Formula: see text] < 0.001 and [Formula: see text] = 5.62, [Formula: see text] = 0.02). CONCLUSION: In axillary node-positive, HR+, and HER2- early BC, amplifications of FGFR1 gene were strongly associated with increased risk for distant disease, while mutations of MAP3K1 gene were significantly associated with decreased risk.

Design and methods of a national, multicenter, randomized and controlled trial to assess the efficacy of a physical activity program to improve health-related quality of life and reduce fatigue in women with metastatic breast cancer: ABLE02 trial.

BACKGROUND: Patients with a metastatic breast cancer suffer from a deteriorated health-related quality of life and numerous symptoms such as pain, severe fatigue and a decrease of their physical fitness. As the feasibility of a physical activity program has been demonstrated in this population, ABLE02 aims to assess the efficacy of a 6 month-physical activity program using connected devices to improve health-related quality of life and to reduce fatigue in women with metastatic breast cancer. METHODS: ABLE02 is a prospective, national, multicenter, randomized, controlled and open-label study. A total of 244 patients with a metastatic breast cancer, with at least one positive hormone receptor and a first-line chemotherapy planned, will be randomly assigned (1:1 ratio) to: (i) the intervention arm to receive physical activity recommendations, an activity tracker to wear 24 h a day during the whole intervention (6 months) with at least three weekly walking sessions and quizzes each week on physical activity and nutrition (ii) the control arm to receive physical activity recommendations only. Health-related quality of life will be assessed every 6 weeks and main assessments will be conducted at baseline, M3, M6, M12 and M18 to evaluate the clinical, physical, biological and psychological parameters and survival of participants. All questionnaires will be completed on a dedicated application. DISCUSSION: An activity program based on a smartphone application linked to an activity tracker may help to improve quality of life and reduce fatigue of patients with a metastatic breast cancer. The growth of e-health offers the opportunity to get real-time data as well as improving patient empowerment in order to change long-term behaviors. TRIAL REGISTRATION: NCT number: NCT04354233 .

Correction to: CD73 expression in normal and pathological human hepatobiliopancreatic tissues.

The following information must be added to the published article.

CD73 expression in normal and pathological human hepatobiliopancreatic tissues.

BACKGROUND: The tumor-expressed CD73 ectonucleotidase generates immune tolerance and promotes invasiveness via adenosine production from degradation of AMP. While anti-CD73 blockade treatment is a promising tool in cancer immunotherapy, a characterization of CD73 expression in human hepatobiliopancreatic system is lacking. PATIENTS AND METHODS: CD73 expression was investigated by immunohistochemistry in a variety of non-neoplastic and neoplastic conditions of the liver, pancreas, and biliary tract. RESULTS: CD73 was expressed in normal hepatobiliopancreatic tissues with subcellular-specific patterns of staining: canalicular in hepatocytes, and apical in cholangiocytes and pancreatic ducts. CD73 was present in all hepatocellular carcinoma (HCC), in all pancreatic ductal adenocarcinoma (PDAC), and in the majority of intra and extrahepatic cholangiocellular carcinomas, whereas it was detected only in a subset of pancreatic neuroendocrine neoplasms and almost absent in acinar cell carcinoma. In addition to the canonical pattern of staining, an aberrant membranous and/or cytoplasmic expression was observed in invasive lesions, especially in HCC and PDAC. These two entities were also characterized by a higher extent and intensity of staining as compared to other hepatobiliopancreatic neoplasms. In PDAC, aberrant CD73 expression was inversely correlated with differentiation (p < 0.01) and was helpful to identify isolated discohesive tumor cells. In addition, increased CD73 expression was associated with reduced overall survival (HR 1.013) and loss of E-Cadherin. CONCLUSIONS: Consistent CD73 expression supports the rationale for testing anti-CD73 therapies in patients with hepatobiliopancreatic malignancies. Specific patterns of expression could also be of help in the routine diagnostic workup.

Genetic alterations and tumor immune attack in Yo paraneoplastic cerebellar degeneration.

Paraneoplastic cerebellar degenerations with anti-Yo antibodies (Yo-PCD) are rare syndromes caused by an auto-immune response against neuronal antigens (Ags) expressed by tumor cells. However, the mechanisms responsible for such immune tolerance breakdown are unknown. We characterized 26 ovarian carcinomas associated with Yo-PCD for their tumor immune contexture and genetic status of the 2 onconeural Yo-Ags, CDR2 and CDR2L. Yo-PCD tumors differed from the 116 control tumors by more abundant T and B cells infiltration occasionally organized in tertiary lymphoid structures harboring CDR2L protein deposits. Immune cells are mainly in the vicinity of apoptotic tumor cells, revealing tumor immune attack. Moreover, contrary to un-selected ovarian carcinomas, 65% of our Yo-PCD tumors presented at least one somatic mutation in Yo-Ags, with a predominance of missense mutations. Recurrent gains of the CDR2L gene with tumor protein overexpression were also present in 59% of Yo-PCD patients. Overall, each Yo-PCD ovarian carcinomas carried at least one genetic alteration of Yo-Ags. These data demonstrate an association between massive infiltration of Yo-PCD tumors by activated immune effector cells and recurrent gains and/or mutations in autoantigen-encoding genes, suggesting that genetic alterations in tumor cells trigger immune tolerance breakdown and initiation of the auto-immune disease.

TLR9 transcriptional regulation in response to double-stranded DNA viruses.

The stimulation of TLRs by pathogen-derived molecules leads to the production of proinflammatory cytokines. Because uncontrolled inflammation can be life threatening, TLR regulation is important; however, few studies have identified the signaling pathways that contribute to the modulation of TLR expression. In this study, we examined the relationship between activation and the transcriptional regulation of TLR9. We demonstrate that infection of primary human epithelial cells, B cells, and plasmacytoid dendritic cells with dsDNA viruses induces a regulatory temporary negative-feedback loop that blocks TLR9 transcription and function. TLR9 transcriptional downregulation was dependent on TLR9 signaling and was not induced by TLR5 or other NF-κB activators, such as TNF-α. Engagement of the TLR9 receptor induced the recruitment of a suppressive complex, consisting of NF-κBp65 and HDAC3, to an NF-κB cis element on the TLR9 promoter. Knockdown of HDAC3 blocked the transient suppression in which TLR9 function was restored. These results provide a framework for understanding the complex pathways involved in transcriptional regulation of TLR9, immune induction, and inflammation against viruses.

Human XCR1+ dendritic cells derived in vitro from CD34+ progenitors closely resemble blood dendritic cells, including their adjuvant responsiveness, contrary to monocyte-derived dendritic cells.

Human monocyte-derived dendritic cell (MoDC) have been used in the clinic with moderately encouraging results. Mouse XCR1(+) DC excel at cross-presentation, can be targeted in vivo to induce protective immunity, and share characteristics with XCR1(+) human DC. Assessment of the immunoactivation potential of XCR1(+) human DC is hindered by their paucity in vivo and by their lack of a well-defined in vitro counterpart. We report in this study a protocol generating both XCR1(+) and XCR1(-) human DC in CD34(+) progenitor cultures (CD34-DC). Gene expression profiling, phenotypic characterization, and functional studies demonstrated that XCR1(-) CD34-DC are similar to canonical MoDC, whereas XCR1(+) CD34-DC resemble XCR1(+) blood DC (bDC). XCR1(+) DC were strongly activated by polyinosinic-polycytidylic acid but not LPS, and conversely for MoDC. XCR1(+) DC and MoDC expressed strikingly different patterns of molecules involved in inflammation and in cross-talk with NK or T cells. XCR1(+) CD34-DC but not MoDC efficiently cross-presented a cell-associated Ag upon stimulation by polyinosinic-polycytidylic acid or R848, likewise to what was reported for XCR1(+) bDC. Hence, it is feasible to generate high numbers of bona fide XCR1(+) human DC in vitro as a model to decipher the functions of XCR1(+) bDC and as a potential source of XCR1(+) DC for clinical use.

PRKDC mutations associated with immunodeficiency, granuloma, and autoimmune regulator-dependent autoimmunity.

BACKGROUND: PRKDC encodes for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a kinase that forms part of a complex (DNA-dependent protein kinase [DNA-PK]) crucial for DNA double-strand break repair and V(D)J recombination. In mice DNA-PK also interacts with the transcription factor autoimmune regulator (AIRE) to promote central T-cell tolerance. OBJECTIVE: We sought to understand the causes of an inflammatory disease with granuloma and autoimmunity associated with decreasing T- and B-cell counts over time that had been diagnosed in 2 unrelated patients. METHODS: Genetic, molecular, and functional analyses were performed to characterize an inflammatory disease evocative of a combined immunodeficiency. RESULTS: We identified PRKDC mutations in both patients. These patients exhibited a defect in DNA double-strand break repair and V(D)J recombination. Whole-blood mRNA analysis revealed a strong interferon signature. On activation, memory T cells displayed a skewed cytokine response typical of TH2 and TH1 but not TH17. Moreover, mutated DNA-PKcs did not promote AIRE-dependent transcription of peripheral tissue antigens in vitro. The latter defect correlated in vivo with production of anti-calcium-sensing receptor autoantibodies, which are typically found in AIRE-deficient patients. In addition, 9 months after bone marrow transplantation, patient 1 had Hashimoto thyroiditis, suggesting that organ-specific autoimmunity might be linked to nonhematopoietic cells, such as AIRE-expressing thymic epithelial cells. CONCLUSION: Deficiency of DNA-PKcs, a key AIRE partner, can present as an inflammatory disease with organ-specific autoimmunity, suggesting a role for DNA-PKcs in regulating autoimmune responses and maintaining AIRE-dependent tolerance in human subjects.

Human natural killer cells promote cross-presentation of tumor cell-derived antigens by dendritic cells.

Dendritic cells (DCs) cross-present antigen (Ag) to initiate T-cell immunity against most infections and tumors. Natural killer (NK) cells are innate cytolytic lymphocytes that have emerged as key modulators of multiple DC functions. Here, we show that human NK cells promote cross-presentation of tumor cell-derived Ag by DC leading to Ag-specific CD8(+) T-cell activation. Surprisingly, cytotoxic function of NK cells was not required. Instead, we highlight a critical and nonredundant role for IFN-γ and TNF-α production by NK cells to enhance cross-presentation by DC using two different Ag models. Importantly, we observed that NK cells promote cell-associated Ag cross-presentation selectively by monocytes-derived DC (Mo-DC) and CD34-derived CD11b(neg) CD141(high) DC subsets but not by myeloid CD11b(+) DC. Moreover, we demonstrate that triggering NK cell activation by monoclonal antibodies (mAbs)-coated tumor cells leads to efficient DC cross-presentation, supporting the concept that NK cells can contribute to therapeutic mAbs efficiency by inducing downstream adaptive immunity. Taken together, our findings point toward a novel role of human NK cells bridging innate and adaptive immunity through selective induction of cell-associated Ag cross-presentation by CD141(high) DC, a process that could be exploited to better harness Ag-specific cellular immunity in immunotherapy.

Paradigm shift in oncology: targeting the immune system rather than cancer cells.

The clinical benefits obtained with rituximab in the treatment of CD20(+) B-cell malignancies and of imatinib in the treatment of Phi(+) leukaemias have opened a new era in oncology, transforming the concepts of tumour-targeted therapies and personalised medicine into reality. Since then, many tumour-targeted monoclonal antibodies and tyrosine kinase inhibitors have been approved for the treatment of cancers. Compared to conventional chemotherapies, these new drugs have more specificity against cancer cells and less systemic toxicities. However, like conventional chemotherapies, they often provide limited therapeutic benefits with short-lasting tumour responses as the vast majority of cancers become resistant to these drugs over time. Therefore, tumour-targeted therapies are an incremental innovation as compared to historical chemotherapies. Recently, a paradigm shift has been brought to the clinic with drugs targeting immune cells rather than cancer cells with the aim of stimulating the anti-tumour immune response of patients against their own cancer. Immunomodulatory drugs such as anti-CTLA4 and anti-PD-1 have generated long-lasting tumour responses when used as single agent in patients with refractory/relapsing cancers such as metastatic melanomas, renal cell carcinoma or non-small-cell lung carcinoma. These new immune-targeted therapies are therefore a disruptive innovation in cancer treatment: they demonstrate that long-lasting clinical benefits could be obtained by targeting molecules involved in the immune tolerance of cancer cells rather than by targeting oncogenic drivers or antigens expressed by cancer cells.

Immunobiology. Combined targeted and immunotherapy: the future of personalized medicine.

In this issue of Blood, Yang et al have demonstrated that the therapeutic activity of a targeted therapy, the tyrosine kinase inhibitor (TKI) dasatinib, unexpectedly depends on antitumor T-cell responses that are strongly potentiated by immunostimulation (agonist anti-OX40).

[Cell therapy in all its forms]. / La thérapie cellulaire dans tous ses états.

Immunotherapy strategies have revolutionized the management of a significant number of patients in recent years, whether they are undergoing treatment for hematologic malignancies or solid tumors. This therapeutic class is extensive, ranging from antibodies targeting immune checkpoint molecules to adoptive cell therapy strategies, including bispecific antibodies and anticancer vaccines. All these strategies are currently in active development. Adoptive cell therapy involves the infusion of normal or genetically modified immune cells into a patient with the aim of restoring strong antitumor immunity, primarily associated with the cytotoxicity of T lymphocytes. Currently, there are three major adoptive cell therapy strategies: allogeneic hematopoietic stem cell transplantation, CAR-T cell therapy, and TCR-T cell therapy. The objective of this article is to describe the mechanisms of action of these three strategies as well as their current advantages, limitations and constraints.

Modulation of blood T cell polyfunctionality and HVEM/BTLA expression are critical determinants of clinical outcome in anti-PD1-treated metastatic melanoma patients.

The need for reliable biomarkers to predict clinical benefit from anti-PD1 treatment in metastatic melanoma (MM) patients remains unmet. Several parameters have been considered in the tumor environment or the blood, but none has yet achieved sufficient accuracy for routine clinical practice. Whole blood samples from MM patients receiving second-line anti-PD1 treatment (NCT02626065), collected longitudinally, were analyzed by flow cytometry to assess the immune cell subsets absolute numbers, the expression of immune checkpoints or ligands on T cells and the functionality of innate immune cells and T cells. Clinical response was assessed according to Progression-Free Survival (PFS) status at one-year following initiation of anti-PD1 (responders: PFS > 1 year; non-responders: PFS ≤ 1 year). At baseline, several phenotypic and functional alterations in blood immune cells were observed in MM patients compared to healthy donors, but only the proportion of polyfunctional memory CD4+ T cells was associated with response to anti-PD1. Under treatment, a decreased frequency of HVEM on CD4+ and CD8+ T cells after 3 months of treatment identified responding patients, whereas its receptor BTLA was not modulated. Both reduced proportion of CD69-expressing CD4+ and CD8+ T cells and increased number of polyfunctional blood memory T cells after 3 months of treatment were associated with response to anti-PD1. Of upmost importance, the combination of changes of all these markers accurately discriminated between responding and non-responding patients. These results suggest that drugs targeting HVEM/BTLA pathway may be of interest to improve anti-PD1 efficacy.

The CSF-1R inhibitor pexidartinib affects FLT3-dependent DC differentiation and may antagonize durvalumab effect in patients with advanced cancers.

Tumor-associated macrophages (TAMs) are a critical determinant of resistance to PD-1/PD-L1 blockade. This phase 1 study (MEDIPLEX, NCT02777710) investigated the safety and efficacy of pexidartinib, a CSF-1R-directed tyrosine kinase inhibitor (TKI), and durvalumab (anti-PD-L1) in patients with advanced colorectal and pancreatic carcinoma with the aim to enhance responses to PD-L1 blockade by eliminating CSF-1-dependent suppressive TAM. Forty-seven patients were enrolled. No unexpected toxicities were observed, one (2%) high microsatellite instability CRC patient had a partial response, and seven (15%) patients experienced stable disease as their best response. Increase of CSF-1 concentrations and decrease of CD14lowCD16high monocytes in peripheral blood mononuclear cells (PBMCs) confirmed CSF-1R engagement. Treatment decreased blood dendritic cell (DC) subsets and impaired IFN-λ/IL-29 production by type 1 conventional DCs in ex vivo TLR3-stimulated PBMCs. Pexidartinib also targets c-KIT and FLT3, both key growth factor receptors of DC development and maturation. In patients, FLT3-L concentrations increased with pexidartinib treatment, and AKT phosphorylation induced by FLT3-L ex vivo stimulation was abrogated by pexidartinib in human blood DC subsets. In addition, pexidartinib impaired the FLT3-L- but not GM-CSF-dependent generation of DC subsets from murine bone marrow (BM) progenitors in vitro and decreased DC frequency in BM and tumor-draining lymph node in vivo. Our results demonstrate that pexidartinib, through the inhibition of FLT3 signaling, has a deleterious effect on DC differentiation, which may explain the limited antitumor clinical activity observed in this study. This work suggests that inhibition of FLT3 should be considered when combining TKIs with immune checkpoint inhibitors.

NF-κB subunits RelA and c-Rel selectively control CD4+ T cell function in multiple sclerosis and cancer.

The outcome of cancer and autoimmunity is often dictated by the effector functions of CD4+ conventional T cells (Tconv). Although activation of the NF-κB signaling pathway has long been implicated in Tconv biology, the cell-autonomous roles of the separate NF-κB transcription-factor subunits are unknown. Here, we dissected the contributions of the canonical NF-κB subunits RelA and c-Rel to Tconv function. RelA, rather than c-Rel, regulated Tconv activation and cytokine production at steady-state and was required for polarization toward the TH17 lineage in vitro. Accordingly, RelA-deficient mice were fully protected against neuroinflammation in a model of multiple sclerosis due to defective transition to a pathogenic TH17 gene-expression program. Conversely, Tconv-restricted ablation of c-Rel impaired their function in the microenvironment of transplanted tumors, resulting in enhanced cancer burden. Moreover, Tconv required c-Rel for the response to PD-1-blockade therapy. Our data reveal distinct roles for canonical NF-κB subunits in different disease contexts, paving the way for subunit-targeted immunotherapies.

Breast cancer-derived transforming growth factor-ß and tumor necrosis factor-α compromise interferon-α production by tumor-associated plasmacytoid dendritic cells.

We previously reported that plasmacytoid dendritic cells (pDCs) infiltrating breast tumors are impaired for their interferon-α (IFN-α) production, resulting in local regulatory T cells amplification. We designed our study to decipher molecular mechanisms of such functional defect of tumor-associated pDC (TApDC) in breast cancer. We demonstrate that besides IFN-α, the production by Toll-like receptor (TLR)-activated healthy pDC of IFN-ß and TNF-α but not IP-10/CXCL10 nor MIP1-α/CCL3 is impaired by the breast tumor environment. Importantly, we identified TGF-ß and TNF-α as major soluble factors involved in TApDC functional alteration. Indeed, recombinant TGF-ß1 and TNF-α synergistically blocked IFN-α production of TLR-activated pDC, and neutralization of TGF-ß and TNF-α in tumor-derived supernatants restored pDCs' IFN-α production. The involvment of tumor-derived TGF-ß was further confirmed in situ by the detection of phosphorylated Smad2 in the nuclei of TApDC in breast tumor tissues. Mechanisms of type I IFN inhibition did not involve TLR downregulation but the inhibition of IRF-7 expression and nuclear translocation in pDC after their exposure to tumor-derived supernatants or recombinant TGF-ß1 and TNF-α. Our findings indicate that targeting TApDC to restore their IFN-α production might be an achievable strategy to induce antitumor immunity in breast cancer by combining TLR7/9-based immunotherapy with TGF-ß and TNF-α antagonists.