FLT3L-dependent dendritic cells control tumor immunity by modulating Treg and NK cell homeostasis.

FLT3-L-dependent classical dendritic cells (cDCs) recruit anti-tumor and tumor-protecting lymphocytes. We evaluate cancer growth in mice with low, normal, or high levels of cDCs. Paradoxically, both low or high numbers of cDCs improve survival in mice with melanoma.

Loss of NOD2 in macrophages improves colitis and tumorigenesis in a lysozyme-dependent manner.

Background: Crohn's disease (CD) is a complex and poorly understood myeloid-mediated disorder. Genetic variants with loss of function in the gene confer an increased susceptibility to ileal CD. While Nod2 in myeloid cells may confer protection against T-cell mediated ileopathy, it remains unclear whether it may promote resolution of the inflamed colon.

CTLA-4 Pathway Is Instrumental in Giant Cell Arteritis.

Background: Giant cell arteritis (GCA) causes severe inflammation of the aorta and its branches and is characterized by intense effector T-cell infiltration. The roles that immune checkpoints play in the pathogenesis of GCA are still unclear. Our aim was to study the immune checkpoint interplay in GCA.

Major histocompatibility class I antigenic peptides derived from translation of pre-mRNAs generate immune tolerance.

Antigenic peptides derived from introns are presented on major histocompatibility (MHC) class I molecules, but how these peptides are produced is poorly understood. Here, we show that an MHC class I epitope (SL8) sequence inserted in the second intron of the β-globin gene in a C57BL/6 mouse (HBB) generates immune tolerance. Introduction of SL8-specific CD8 T cells derived from OT-1 transgenic mice resulted in a threefold increase in OT-1 T cell proliferation in HBB animals, as compared to wild-type animals.

Synthetic Melanin Acts as Efficient Peptide Carrier in Cancer Vaccine Strategy.

We previously reported that a novel peptide vaccine platform, based on synthetic melanin nanoaggregates, triggers strong cytotoxic immune responses and significantly suppresses tumor growth in mice. However, the mechanisms underlying such an efficacy remained poorly described. Herein, we investigated the role of dendritic cells (DCs) in presenting the antigen embedded in the vaccine formulation, as well as the potential stimulatory effect of melanin upon these cells, in vitro by coculture experiments and ELISA/flow cytometry analysis.

UNC93B1 interacts with the calcium sensor STIM1 for efficient antigen cross-presentation in dendritic cells.

Dendritic cells (DC) have the unique ability to present exogenous antigens via the major histocompatibility complex class I pathway to stimulate naive CD8 T cells. In DCs with a non-functional mutation in Unc93b1 (3d mutation), endosomal acidification, phagosomal maturation, antigen degradation, antigen export to the cytosol and the function of the store-operated-Ca-entry regulator STIM1 are impaired. These defects result in compromised antigen cross-presentation and anti-tumor responses in 3d-mutated mice.

Methods to Study Metastasis in Genetically Modified Mice.

Metastasis is often modeled by xenotransplantation of cell lines in immunodeficient mice. A wealth of information about tumor cell behavior in the new environment is obtained from these efforts. Yet by design, this approach is "tumor-centric," as it focuses on cell-autonomous determinants of human tumor dissemination in mouse tissues, in effect using the animal body as a sophisticated "Petri dish" providing nutrients and support for tumor growth.

Enrichment of Mammary Basal and Luminal Cells for Cell-of-Origin Metastasis Studies.

The mammary gland is an important model system in metastasis research. Mammary epithelial stem cells are of particular interest because of their capacity for regeneration and their role in cancer initiation. This protocol describes how to enrich for mammary basal and luminal epithelial cells using fluorescence-activated cell sorting (FACS).

Methods to study primary tumor cells and residual tumor cells in mouse models of oncogene dependence.

The studies of oncogene dependence are aimed to understand an unfortunate and puzzling aspect of targeted anticancer treatments-their progression to drug resistance. Drug resistance develops from a pool of cells that survive the original treatment, called minimal residual disease. Mouse models based on tetracycline-dependent expression of transgenic oncogenes are used to imitate targeted oncogene blockade and to reproduce minimal residual disease in humans.

How numbers, nature, and immune status of foxp3(+) regulatory T-cells shape the early immunological events in tumor development.

The influence of CD4(+)CD25(+)Foxp3(+) regulatory T-cells (Tregs) on cancer progression has been demonstrated in a large number of preclinical models and confirmed in several types of malignancies. Neoplastic processes trigger an increase of Treg numbers in draining lymph nodes, spleen, blood, and tumors, leading to the suppression of anti-tumor responses. Treg-depletion before or early in tumor development may lead to complete tumor eradication and extends survival of mice and humans.

Self-specific memory regulatory T cells protect embryos at implantation in mice.

Regulatory T cells (Tregs) play crucial roles in both fetal and tumor development. We recently showed that immunosurveillance by pre-existing CD44(high)CD62L(low) activated/memory Tregs (amTregs) specific for self-Ags protects emergent tumor cells in mice. This Treg response of a memory type is more rapid than and dominates the antitumor response of tumor-specific effector T cells.

Expression of the zinc finger transcription factor zDC (Zbtb46, Btbd4) defines the classical dendritic cell lineage.

Classical dendritic cells (cDCs), monocytes, and plasmacytoid DCs (pDCs) arise from a common bone marrow precursor (macrophage and DC progenitors [MDPs]) and express many of the same surface markers, including CD11c. We describe a previously uncharacterized zinc finger transcription factor, zDC (Zbtb46, Btbd4), which is specifically expressed by cDCs and committed cDC precursors but not by monocytes, pDCs, or other immune cell populations. We inserted diphtheria toxin (DT) receptor (DTR) cDNA into the 3' UTR of the zDC locus to serve as an indicator of zDC expression and as a means to specifically deplete cDCs.

Dll4-Notch signaling in Flt3-independent dendritic cell development and autoimmunity in mice.

Delta-like ligand 4 (Dll4)-Notch signaling is essential for T cell development and alternative thymic lineage decisions. How Dll4-Notch signaling affects pro-T cell fate and thymic dendritic cell (tDC) development is unknown. We found that Dll4 pharmacological blockade induces accumulation of tDCs and CD4(+)CD25(+)FoxP3(+) regulatory T cells (T(reg) cells) in the thymic cortex.

An altered peptide ligand corresponding to a novel epitope from heat-shock protein 60 induces regulatory T cells and suppresses pathogenic response in an animal model of adjuvant-induced arthritis.

Induction of immune tolerance as therapeutic approach for autoimmune diseases constitutes a current research focal point. In this sense, we aimed to evaluate an altered peptide ligand (APL) for induction of peripheral tolerance in patients with rheumatoid arthritis (RA). A novel T-cell epitope from human heat-shock protein 60 (Hsp60), an autoantigen involved in the pathogenesis of RA, was identified by bioinformatics tools and an APL was design starting from this epitope.

Feedback control of regulatory T cell homeostasis by dendritic cells in vivo.

CD4(+)CD25(+)Foxp3(+) natural regulatory T cells (T reg cells) maintain self-tolerance and suppress autoimmune diseases such as type 1 diabetes and inflammatory bowel disease (IBD). In addition to their effects on T cells, T reg cells are essential for maintaining normal numbers of dendritic cells (DCs): when T reg cells are depleted, there is a compensatory Flt3-dependent increase in DCs. However, little is known about how T reg cell homeostasis is maintained in vivo.

Tumor emergence is sensed by self-specific CD44hi memory Tregs that create a dominant tolerogenic environment for tumors in mice.

Early responses of Tregs and effector T cells (Teffs) to their first encounter with tumor cells have been poorly characterized. Here we have shown, in both implanted and in situ-induced mouse tumor models, that the appearance of tumor cells is immediately sensed by CD44hi memory Tregs that are specific for self antigens. The rapid response of these Tregs preceded and prevented activation of naive antitumor Teffs.

The receptor tyrosine kinase Flt3 is required for dendritic cell development in peripheral lymphoid tissues.

Dendritic cell (DC) development begins in the bone marrow but is not completed until after immature progenitors reach their sites of residence in lymphoid organs. The hematopoietic growth factors regulating these processes are poorly understood. Here we examined the effects of signaling by the receptor tyrosine kinase Flt3 on macrophage DC progenitors in the bone marrow and on peripheral DCs.

Regulatory T cells prevent CD8 T cell maturation by inhibiting CD4 Th cells at tumor sites.

Natural regulatory T cells (Tregs) are present in high frequencies among tumor-infiltrating lymphocytes and in draining lymph nodes, supposedly facilitating tumor development. To investigate their role in controlling local immune responses, we analyzed intratumoral T cell accumulation and function in the presence or absence of Tregs. Tumors that grew in normal BALB/c mice injected with the 4T1 tumor cell line were highly infiltrated by Tregs, CD4 and CD8 cells, all having unique characteristics.

Chemoimmunotherapy of tumors: cyclophosphamide synergizes with exosome based vaccines.

Dendritic cell-derived exosomes (DEX) are nanomeric vesicles harboring MHC/peptide complexes capable of promoting primary T cell responses and tumor rejection in the presence of adjuvants. In this study, we show that, in the absence of adjuvants, DEX mediate potent Ag-dependent antitumor effects against preestablished tumors in mice pretreated with immunopotentiating dosing of cyclophosphamide. Cyclophosphamide could 1) abolish the suppressive function of CD4+CD25+Foxp3+ regulatory T cells, 2) markedly enhance the magnitude of secondary but not primary CTL responses induced by DEX vaccines, 3) synergize with DEX in therapy but not prophylaxis tumor models.

CD4+CD25+ regulatory/suppressor T cells prevent allogeneic fetus rejection in mice.

Recent evidences indicate that naturally occurring CD4+CD25+ regulatory/suppressor T cells (T(reg)) regulate not only autoimmunity, but also alloreactivity. In mice, they notably control tolerance to allogeneic transplants and graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Here, we studied the role of T(reg) in maternal tolerance to fetuses, i.

Ontogeny of CD4+CD25+ regulatory/suppressor T cells in human fetuses.

Little is known about the ontogeny of naturally occurring CD4(+)CD25(+) regulatory/suppressor T cells that play a major role in maintaining self-tolerance in mice and humans. In rodents, thymectomy on day 3 of life leads to multiple organ-specific autoimmune diseases that can be prevented by adoptive transfer of regulatory T cells, suggesting their neonatal development. We investigated regulatory T-cell ontogeny in 11 human fetuses.

Continuous activation of autoreactive CD4+ CD25+ regulatory T cells in the steady state.

Despite a growing interest in CD4+ CD25+ regulatory T cells (Treg) that play a major role in self-tolerance and immunoregulation, fundamental parameters of the biology and homeostasis of these cells are poorly known. Here, we show that this population is composed of two Treg subsets that have distinct phenotypes and homeostasis in normal unmanipulated mice. In the steady state, some Treg remain quiescent and have a long lifespan, in the order of months, whereas the other Treg are dividing extensively and express multiple activation markers.