The functions and transcriptional profiles of dendritic cells (DCs) result from the interplay between ontogeny and tissue imprinting. How tumors shape human DCs is unknown. Here we used RNA-based next-generation sequencing to systematically analyze the transcriptomes of plasmacytoid pre-DCs (pDCs), cell populations enriched for type 1 conventional DCs (cDC1s), type 2 conventional DCs (cDC2s), CD14 DCs and monocytes-macrophages from human primary luminal breast cancer (LBC) and triple-negative breast cancer (TNBC). By comparing tumor tissue with non-invaded tissue from the same patient, we found that 85% of the genes upregulated in DCs in LBC were specific to each DC subset. However, all DC subsets in TNBC commonly showed enrichment for the interferon pathway, but those in LBC did not. Finally, we defined transcriptional signatures specific for tumor DC subsets with a prognostic effect on their respective breast-cancer subtype. We conclude that the adjustment of DCs to the tumor microenvironment is subset specific and can be used to predict disease outcome. Our work also provides a resource for the identification of potential targets and biomarkers that might improve antitumor therapies.

The CCL2 chemokine receptor CCR2 drives cancer by mediating the recruitment of monocytes and myeloid-derived suppressor cells to the tumor microenvironment. In this study, we extend the significance of CCR2 in this setting by identifying a new role for it in mediating recruitment of CD4 T regulatory cells (Treg). Following tumor initiation, an expanded population of CCR2 Tregs required CCR2 expression to traffic between draining lymph nodes (dLN) and the tumor. This Treg subset was enriched in the fraction of tumor antigen-specific cells in the dLN, where they displayed an activated immunosuppressive phenotype. Notably, in mouse models, low-dose cyclophosphamide treatment preferentially depleted CCR2 Treg, enhancing priming of tumor-specific CD8 T cells. In the MMTV-PyMT transgenic mouse model of breast cancer and in oral squamous cell carcinoma patients, tumor development was associated with decreased blood frequency and inversely increased tumor frequency of CCR2 Tregs. Our results define a novel subset of CCR2 Treg involved in tumoral immune escape, and they offer evidence that this Treg subset may be preferentially eradicated by low-dose cyclophosphamide treatment. Cancer Res; 76(22); 6483-94. ©2016 AACR.

Although the COVID‐19 pandemic peaked in March/April 2020 in France, the prevalence of infection is barely known. Using high‐throughput methods, we assessed herein the serological response against the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) of 1847 participants working in three sites of an institution in Paris conurbation. In May–July 2020, 11% (95% confidence interval [CI]: 9.7–12.6) of serums were positive for IgG against the SARS‐CoV‐2 N and S proteins, and 9.5% (95% CI: 8.2–11.0) were neutralizer in pseudo‐typed virus assays. The prevalence of seroconversion was 11.6% (95% CI: 10.2–13.2) when considering positivity in at least one assay. In 5% of RT‐qPCR positive individuals, no systemic IgGs were detected. Among immune individuals, 21% had been asymptomatic. Anosmia (loss of smell) and ageusia (loss of taste) occurred in 52% of the IgG‐positive individuals and in 3% of the negative ones. In contrast, 30% of the anosmia–ageusia cases were seronegative, suggesting that the true prevalence of infection may have reached 16.6%. In sera obtained 4–8 weeks after the first sampling, anti‐N and anti‐S IgG titers and neutralization activity in pseudo‐virus assay declined by 31%, 17%, and 53%, resulting thus in half‐life of 35, 87, and 28 days, respectively. The population studied is representative of active workers in Paris. The short lifespan of the serological systemic responses suggests an underestimation of the true prevalence of infection.

By revisiting CD90, a GPI-anchored glycoprotein, we show that CD90 is expressed by a subset of CD4+ and CD8+ human T cells. CD4+CD90+ cells share similarities with Th17 cells because they express the Th17-specific transcription factor RORC2 and produce IL-17A. CD4+CD90+ cells are activated memory T cells that express the gut mucosal markers CCR6, CD161, and the α4 and β7 integrins. Compared with CD90-depleted CCR6+ memory Th17 cells, CD4+CD90+ cells express higher levels of IL-22 and proinflammatory cytokines (IL-6, TNF-α and GM-CSF), but they produce lower levels of IL-21 and no IL-9. Analyses of CD8+CD90+ cells reveal that they express RORC2 and are able to produce higher levels of IL-17A, IL-22, and CCL20 compared with CD90-depleted CD8+ cells. These data show that CD90 identifies Th17 and Tc17 cells with a peculiar cytokine profile. Studies of circulating CD90+ cells in HIV patients show that CD90+ cells are decreased with an imbalance of the CD4+CD90+/regulatory T cell ratio in nontreated patients compared with treated patients and healthy donors. Overall, human CD90 identifies a subset of Th17 and Tc17 cells within CD4+ and CD8+ T cells, respectively, which are depleted during HIV infection.

Background Although the COVID-19 pandemic peaked in March/April 2020 in France, the prevalence of infection is barely known. Herein, we assessed the serological response against the SARS-CoV-2 virus in a large population working in one institution of the Paris conurbation. We set up two high-throughput and sensitive methods to assess SARS CoV-2 Nucleoprotein and Spike protein-specific IgG response along with a pseudo-neutralization assay in sera. We studied 1847 participants who also answered a web-based survey on clinical symptoms. Methods and Results In May-July 2020, 11% (95% CI: 9.7-12.6) of serums were positive for IgG against the SARS-CoV-2 N and S protein and 9.5% (CI:8.2-11.0) were pseudo-neutralizer. The prevalence of immunization was 11.6% (CI:10.2-13.2) considering positivity in at least one assays. In 5% (CI:3.9-7.1) of RT-qPCR positive individuals, no systemic IgGs were detected. Among immune individuals, 21% had been asymptomatic. Anosmia and ageusia occurred in 52% of the IgG-positive individuals and in 3% of the negative ones. In contrast, 30% of the anosmia-ageusia cases were seronegative suggesting that the true prevalence of infection may reach 16.6%. In sera obtained 4-8 weeks after the first sampling anti-N and anti-S IgG titers and pseudo-neutralization activity declined by 31%, 17% and 53%, respectively with half-life of 35, 87 and 28 days, respectively. Conclusions The population studied being not particularly exposed to SARS-CoV-2 infection is representative of active workers in the Paris conurbation, suggesting that the current epidemiological models may underestimate the true prevalence of infection. The short lifespan of the serological systemic responses hinders retrospective assessment of the epidemic extent.

The efficient procedure reported here for the preparation of nTreg, whose safety has been ensured, is now applicable for further clinical trials.

Natural regulatory T cells (Tregs) may have a great therapeutic potential to induce tolerance in allogeneic cells and organ transplantations. In mice, we showed that alloantigen-specific Tregs (spe-Tregs) were more efficient than polyclonal Tregs (poly-Tregs) in controlling graft-versus-host disease (GVHD). Here we describe a clinical-grade compliant method for generating human spe-Tregs. Tregs were enriched from leukapheresis products with anti-CD25 immunomagnetic beads, primed twice by allogeneic mature monocyte-derived dendritic cells (mDCs), and cultured during 3 weeks in medium containing interleukin 2 (IL-2), IL-15, and rapamycin. After 3 weeks of culture, final cell products were expanded 8.3-fold from the initial CD25(+) purifications. Immunophenotypic analyses of final cells indicate that they were composed of 88 ± 2.6% of CD4(+) T cells, all expressing Treg-specific markers (FOXP3, Helios, GARP, LAP, and CD152). Spe-Tregs were highly suppressive in vitro and also in vivo using a xeno-GVHD model established in immunodeficient mice. The specificity of their suppressive activity was demonstrated on their ability to significantly suppress the proliferation of autologous effector T cells stimulated by the same mDCs compared to third-party mDCs. Our data provide evidence that functional alloantigen Tregs can be generated under clinical-grade compliant conditions. Taking into account that 130 × 10(6) CD25(+) cells can be obtained at large scale from standard leukapheresis, our cell process may give rise to a theoretical final number of 1 × 10(9) spe-Tregs. Thus, using our strategy, we can propose to prepare spe-Tregs for clinical trials designed to control HLA-mismatched GVHD or organ transplantation rejection.

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