To reach the site of antigen deposition at epithelial surfaces, dendritic cells (DC) have to traverse the endothelial barrier, progress through the tissue (i.e., dermis) and cross the dermo-epithelial junction (basal membrane). In the present study, we demonstrate that (1) circulating blood DC and monocytes express high levels of CCR2 and primarily respond to monocyte chemotactic protein (MCP) and not to macrophage inflammatory protein (MIP)-3alpha/CCL20; (2) while the CD34(+) hematopoietic progenitor cells (HPC)-derived CD1a(+) precursors committed to Langerhans cell differentiation primarily respond to MIP-3alpha/CCL20, the HPC-derived CD14(+) precursors respond to both MCP and MIP-3alpha/CCL20; (3) in concordance with the sequential expression of CCR2 and CCR6, the HPC-derived CD14(+) precursors initially acquire the ability to migrate in response to MCP-4/CCL13 and subsequently in response to MIP-3alpha/CCL20; and (4) in vivo, in inflamed epithelium, MCP-4/CCL13 and MIP-3alpha/CCL20 form complementary gradients, with MCP-4/CCL13 expressed in basal epithelial cells at the contact of blood vessels, while MIP-3alpha/CCL20 expression is restricted to epithelial cells bordering the external milieu. These observations suggest that the recruitment of DC to the site of infection is controlled by the sequential action of different chemokines: (i) CCR2(+) circulating DC or DC precursors are mobilized into the tissue via the expression of MCP by cells lining blood vessels, and (ii) these cells traffic from the tissue to the site of pathogen invasion via the production of MIP-3alpha/CL20 by epithelial cells and the up-regulation of CCR6 in response to the tissue environment.
Abstract Our group and others have previously reported that Treg infiltrating (Ti-Treg) breast tumors have a negative impact on patients’ outcome. We further reported their selective recruitment in the tumor environment through CCL22 secretion and expansion upon ICOS engagement by plasmacytoïd dendritic cells. Here, we investigated the mechanism of Ti-Treg mediated suppression and observed that Ti-Treg express high CD39 levels. CD39 is an ectonucleotidase that cooperates with CD73 to degrade the danger signal ATP into immunosuppressive Adenosine (Ado). The potency of Ado mediated suppression is illustrated in Adenosine-Deaminase (ADA)-deficient patients unable to degrade Ado and developing severe immunodeficiency. We further show that, in contrast to murine Treg, human CD39+Treg do not express CD73 enabling them only to degrade ATP into AMP. Within T cells, CD73 expression was mainly associated with naïve CD8+ T cells and a subset of memory conventional CD4+ T cells (Tconv) that exhibit Th1/Th17 characteristics (CXCR3+CCR6+CCR4negIFNγhighIL17+). CD39+ Treg isolated from healthy donor blood, in presence of exogenous ATP, potently inhibit purified CD73+ but not CD73neg Tconv, proliferation and cytokine production (IFNγ, TNFα). By using enzymatic inhibitors, we demonstrated the involvement of CD39 and CD73 through Treg/Tconv cooperation for Ado mediated immunosuppression. Of importance, when integrated in [Treg-CD4+CD73+] high density coculture, CD4+CD73neg T cells expressing similar levels of Ado receptors (A2A, A2B) are also inhibited. In conclusion, our findings support the existence of an Ado mediated immunosuppression loop in the tumor through cooperation between CD39highTreg and CD73-expressing Th1/Th17 subsets in the breast tumor environment. The research leading to these results has received funding from the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement n°602200. Citation Format: Nicolas Gourdin, Céline Rodriguez, Selena Vigano, Isabelle Durand, Julien Faget, Camilla Jandus, Jean Yves Blay, Pedro Romero, Christine Menetrier-Caux, Christophe Caux. CD39+ Treg cooperate with a CD73-expressing Th1/Th17 subset for Adenosine-mediated immunosuppression in human breast tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2338.
In ovarian cancer, the immune system fails to eradicate established tumors partly due to the induction of immune tolerance within tumor microenvironment. In this study, we investigated the contribution of plasmacytoid dendritic cells (pDC) in the establishment of immune tolerance in a cohort of 44 ovarian cancer patients. In the tumor and malignant ascites, CD4(+)CD123(+)BDCA2(+) pDC were the most abundant dendritic cell subset; however, they were profoundly depleted in peripheral blood. The presence of pDC in primary ovarian cancer, but not ascites, was an independent prognostic factor associated with early relapse. Following chemotherapy, we observed a partial restoration of blood pDC levels in patients in complete remission. These findings show preferential recruitment of pDC into tumors where they express a partially mature phenotype that may reflect an in situ activation. Importantly, compared with pDC found in ascites or blood, tumor-associated pDC (TApDC) produced less IFN-α, TNF-α, IL-6, macrophage inflammatory protein-1β, and RANTES in response to toll-like receptor stimulation, and alterations in pDC functions were mainly mediated through tumor-derived TNF-α and TGF-β. Unlike ascites-derived pDC, TApDC induced IL-10 production from allogeneic naive CD4(+) T lymphocytes, suggesting the existence of a paracrine immunosuppressive loop. Taken together, our findings indicate that both local and systemic dysfunction of pDC play a critical role in the progression of ovarian cancer via induction of immune tolerance.
Abstract Immunohistochemical analysis of FOXP3 in primary breast tumors showed that a high number of tumor-infiltrating regulatory T cells (Ti-Treg) within lymphoid infiltrates surrounding the tumor was predictive of relapse and death, in contrast to those present within the tumor bed. Ex vivo analysis showed that these tumor-infiltrating FOXP3+ T cells are typical Treg based on their CD4+CD25highCD127lowFOXP3+ phenotype, their anergic state on in vitro stimulation, and their suppressive functions. These Ti-Treg could be selectively recruited through CCR4 as illustrated by (a) selective blood Treg CCR4 expression and migration to CCR4 ligands, (b) CCR4 down-regulation on Ti-Treg, and (c) correlation between Ti-Treg in lymphoid infiltrates and intratumoral CCL22 expression. Importantly, in contrast to other T cells, Ti-Treg are selectively activated locally and proliferate in situ, showing T-cell receptor engagement and suggesting specific recognition of tumor-associated antigens (TAA). Immunohistochemical stainings for ICOS, Ki67, and DC-LAMP show that Ti-Treg were close to mature DC-LAMP+ dendritic cells (DC) in lymphoid infiltrates but not in tumor bed and were activated and proliferating. Furthermore, proximity between Ti-Treg, CD3+, and CD8+ T cells was documented within lymphoid infiltrates. Altogether, these results show that Treg are selectively recruited within lymphoid infiltrates and activated by mature DC likely through TAA presentation, resulting in the prevention of effector T-cell activation, immune escape, and ultimately tumor progression. This study sheds new light on Treg physiology and validates CCR4/CCL22 and ICOS as therapeutic targets in breast tumors, which represent a major health problem. [Cancer Res 2009;69(5):2000–9]
Abstract Tumor immunosubversion occurs through various mechanisms including the selective recruitment of CD4+ regulatory T cell (Treg) and the alteration of dendritic cell (DC) physiology. We reported that the presence of high number of both Treg and/or plasmacytoid DC (pDC) correlates with poor prognosis in breast (1-2) and ovarian carcinoma (3). We previously demonstrated that CCR4+ Treg are recruited from the periphery to the breast tumor through CCL22 production by breast tumor cells under exposure to IFNg, IL-1b and TNFa, consecutively to Macrophages and Natural killer cell detection of transformed cells (4). We report here that Tumor-associated Treg (Ta-Treg) are highly activated (GITRhighHLA-DRhighCD39high) and show a selective expression of high levels of ICOS, proliferate in situ (Ki-67+) but unlike blood Treg, did not proliferate ex vivo under CD3/CD28 co-stimulation in presence of IL-2. On the other hand, Ta-pDC expressed a partially activated phenotype but lacked their principal function, i.e., their type-I interferon production (key mediator of antiviral and tumoral immune responses), is strongly impaired. We show that Ta-Treg and Ta-pDC colocalize within lymphoid structures in vivo and demonstrate the unique capacity of Ta-pDC to favour proliferation of Ta-Treg and CD4+ T cells secreting IL-10. Of importance, this Treg amplification is strongly reduced by addition of exogenous IFNa. Furthermore, targeting ICOS with a neutralizing antibody suppresses Ta-Treg proliferation as well as IL-10 secretion in pDC/CD4+ T cell co-culture, demonstrating a role of ICOS-ICOS-L interaction in Ta-Treg proliferation mediated by Ta-pDC. In contrast, blocking ICOS does not impact T cell responses induced by mDC that, contrary to pDC, do not support Treg enrichment or high IL-10 secretion. Altogether these observations suggest that ICOS represents a therapeutic target in breast cancer that may allow to restore anti-tumor immunity. Grant supports: BCRF, Ligue nationale contre le cancer, ARC, Comité départementaux de la Ligue contre le cancer, INCa. 1. Treilleux I, Blay JY, Bendriss-Vermare N, et al. Dendritic cell infiltration and prognosis of early stage breast cancer. Clin Cancer Res. 2004; 10:7466-74. 2. Gobert M.., Caux C., Blay JY. and Ménétrier-Caux C. Treg recruited through CCL22/CCR4 are selectively activated in lymphoid infiltrates surrounding primary breast tumors and lead to an adverse clinical outcome. Cancer Research 2009; 69:2000-9. 3. Labidi-Galy SI, Ray-Coquard I, Ménétrier-Caux C, Caux C, Blay JY and Bendriss-Vermare N. Systemic and local dysfunctions of pDC in ovarian carcinoma could contribute to immune tolerance. Cancer Res. 2011; 71:5423-34 4. Faget J., Blay J.Y., Caux C. and Ménétrier-Caux C. Early detection of tumor cells by innate immune cells leads to Treg recruitment through CCL22 production by tumor cells. Cancer Res. 2011; 71:6143-52 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5402. doi:1538-7445.AM2012-5402
In this study, we describe human FDF03, a novel member of the Ig superfamily expressed as a monomeric 44-kDa transmembrane glycoprotein and containing a single extracellular V-set Ig-like domain. Two potential secreted isoforms were also identified. The gene encoding FDF03 mapped to chromosome 7q22. FDF03 was mostly detected in hemopoietic tissues and was expressed by monocytes, macrophages, and granulocytes, but not by lymphocytes (B, T, and NK cells), indicating an expression restricted to cells of the myelomonocytic lineage. FDF03 was also strongly expressed by monocyte-derived dendritic cells (DC) and preferentially by CD14+/CD1a- DC derived from CD34+ progenitors. Moreover, flow cytometric analysis showed FDF03 expression by CD11c+ blood and tonsil DC, but not by CD11c- DC precursors. The FDF03 cytoplasmic tail contained two immunoreceptor tyrosine-based inhibitory motif (ITIM)-like sequences. When overexpressed in pervanadate-treated U937 cells, FDF03 was tyrosine-phosphorylated and recruited Src homology-2 (SH2) domain-containing protein tyrosine phosphatase (SHP)-2 and to a lesser extent SHP-1. Like engagement of the ITIM-bearing receptor LAIR-1/p40, cross-linking of FDF03 inhibited calcium mobilization in response to CD32/FcgammaRII aggregation in transfected U937 cells, thus demonstrating that FDF03 can function as an inhibitory receptor. However, in contrast to LAIR-1/p40, cross-linking of FDF03 did not inhibit GM-CSF-induced monocyte differentiation into DC. Thus, FDF03 is a novel ITIM-bearing receptor selectively expressed by cells of myeloid origin, including DC, that may regulate functions other than that of the broadly distributed LAIR-1/p40 molecule.
Abstract We have identified a novel member of the calcium-dependent (C-type) lectin family. This molecule, designated DCIR (for dendritic cell (DC) immunoreceptor), is a type II membrane glycoprotein of 237 aa with a single carbohydrate recognition domain (CRD), closest in homology to those of the macrophage lectin and hepatic asialoglycoprotein receptors. The intracellular domain of DCIR contains a consensus immunoreceptor tyrosine-based inhibitory motif. A mouse cDNA, encoding a homologous protein has been identified. Northern blot analysis showed DCIR mRNA to be predominantly transcribed in hematopoietic tissues. The gene encoding human DCIR was localized to chromosome 12p13, in a region close to the NK gene complex. Unlike members of this complex, DCIR displays a typical lectin CRD rather than an NK cell type extracellular domain, and was expressed on DC, monocytes, macrophages, B lymphocytes, and granulocytes, but not detected on NK and T cells. DCIR was strongly expressed by DC derived from blood monocytes cultured with GM-CSF and IL-4. DCIR was mostly expressed by monocyte-related rather than Langerhans cell related DC obtained from CD34+ progenitor cells. Finally, DCIR expression was down-regulated by signals inducing DC maturation such as CD40 ligand, LPS, or TNF-α. Thus, DCIR is differentially expressed on DC depending on their origin and stage of maturation/activation. DCIR represents a novel surface molecule expressed by Ag presenting cells, and of potential importance in regulation of DC function.
