DNGR-1(+) dendritic cells are located in meningeal membrane and choroid plexus of the noninjured brain.

The role and different origin of brain myeloid cells in the brain is central to understanding how the central nervous system (CNS) responds to injury. C-type lectin receptor family 9, member A (DNGR-1/CLEC9A) is a marker of specific DC subsets that share functional similarities, such as CD8α(+) DCs in lymphoid tissues and CD103(+) CD11b(low) DCs in peripheral tissues. Here, we analyzed the presence of DNGR-1 in DCs present in the mouse brain (bDCs). Dngr-1/Clec9a mRNA is expressed mainly in the meningeal membranes and choroid plexus (m/Ch), and its expression is enhanced by fms-like tyrosine kinase 3 ligand (Flt3L), a cytokine involved in DC homeostasis. Using Clec9a(egfp/egfp) mice, we show that Flt3L induces accumulation of DNGR-1-EGFP(+) cells in the brain m/Ch. Most of these cells also express major histocompatibility complex class II (MHCII) molecules. We also observed an increase in specific markers of cDC CD8α+ cells such as Batf-3 and Irf-8, but not of costimulatory molecules such as Cd80 and Cd86, indicating an immature phenotype for these bDCs in the noninjured brain. The presence of DNGR-1 in the brain provides a potential marker for the study of this specific brain cell subset. Knowledge and targeting of brain antigen presenting cells (APCs) has implications for the fight against brain diseases such as neuroinflammation-based neurodegenerative diseases, microbe-induced encephalitis, and brain tumors such as gliomas.

Quintana E ，Fernández A ，Velasco P ，de Andrés B ，Liste I ，Sancho D ，Gaspar ML ，Cano E ... -  《-》

DNGR-1 is a specific and universal marker of mouse and human Batf3-dependent dendritic cells in lymphoid and nonlymphoid tissues.

Poulin LF ，Reyal Y ，Uronen-Hansson H ，Schraml BU ，Sancho D ，Murphy KM ，Håkansson UK ，Moita LF ，Agace WW ，Bonnet D ，Reis e Sousa C ... -  《-》

DNGR-1 limits Flt3L-mediated antitumor immunity by restraining tumor-infiltrating type I conventional dendritic cells.

Conventional type 1 dendritic cells (cDC1s) are central to antitumor immunity and their presence in the tumor microenvironment associates with improved outcomes in patients with cancer. DNGR-1 (CLEC9A) is a dead cell-sensing receptor highly restricted to cDC1s. DNGR-1 has been involved in both cross-presentation of dead cell-associated antigens and processes of disease tolerance, but its role in antitumor immunity has not been clarified yet. B16 and MC38 tumor cell lines were inoculated subcutaneously into wild-type (WT) and DNGR-1-deficient mice. To overexpress Flt3L systemically, we performed gene therapy through the hydrodynamic injection of an Flt3L-encoding plasmid. To characterize the immune response, we performed flow cytometry and RNA-Seq of tumor-infiltrating cDC1s. Here, we found that cross-presentation of tumor antigens in the steady state was DNGR-1-independent. However, on Flt3L systemic overexpression, tumor growth was delayed in DNGR-1-deficient mice compared with WT mice. Of note, this protection was recapitulated by anti-DNGR-1-blocking antibodies in mice following Flt3L gene therapy. This improved antitumor immunity was associated with Batf3-dependent enhanced accumulation of CD8+ T cells and cDC1s within tumors. Mechanistically, the deficiency in DNGR-1 boosted an Flt3L-induced specific inflammatory gene signature in cDC1s, including Ccl5 expression. Indeed, the increased infiltration of cDC1s within tumors and their protective effect rely on CCL5/CCR5 chemoattraction. Moreover, FLT3LG and CCL5 or CCR5 gene expression signatures correlate with an enhanced cDC1 signature and a favorable overall survival in patients with cancer. Notably, cyclophosphamide elevated serum Flt3L levels and, in combination with the absence of DNGR-1, synergized against tumor growth. DNGR-1 limits the accumulation of tumor-infiltrating cDC1s promoted by Flt3L. Thus, DNGR-1 blockade may improve antitumor immunity in tumor therapy settings associated to high Flt3L expression.

Cueto FJ ，Del Fresno C ，Brandi P ，Combes AJ ，Hernández-García E ，Sánchez-Paulete AR ，Enamorado M ，Bromley CP ，Gomez MJ ，Conde-Garrosa R ，Mañes S ，Zelenay S ，Melero I ，Iborra S ，Krummel MF ，Sancho D ... -  《Journal for ImmunoTherapy of Cancer》

Antibody responses initiated by Clec9A-bearing dendritic cells in normal and Batf3(-/-) mice.

Injection of antigens coupled to antibodies against the dendritic cell (DC) surface molecule Clec9A has been shown to produce strongly enhanced antibody responses even without co-administration of adjuvants, via antigen presentation by DC on MHC class II and consequent production of follicular helper T cells. A series of mutant mice were tested to determine the DC subtypes responsible for this MHC II presentation of targeted antigen, compared to presentation of antigen on MHC I. A new clec9A null mouse was developed; these mice did not give enhanced antibody production, confirming the response was dependent on Clec9A-expressing DC. However targeting of antigen to Clec9A in batf3 null mice produced enhanced antibody responses despite the marked reduction in CD8(+) DC, the major Clec9A-expressing DC subtype. This was shown to be dependent on efficient MHC II presentation by minor Clec9A-expressing DC subtypes in the environment of the Batf3(-/-) mice, namely early cells of the CD8 DC lineage and the plasmacytoid-related CD8(+) DC subset, but not by plasmacytoid cells themselves. However in normal mice most MHC II presentation of the Clec9A-targeted antigen was by the major CD8(+) DC population, the DC also responsible for presentation on MHC I.

Caminschi I ，Vremec D ，Ahmet F ，Lahoud MH ，Villadangos JA ，Murphy KM ，Heath WR ，Shortman K ... -  《-》

Flt3L controls the development of radiosensitive dendritic cells in the meninges and choroid plexus of the steady-state mouse brain.

Anandasabapathy N ，Victora GD ，Meredith M ，Feder R ，Dong B ，Kluger C ，Yao K ，Dustin ML ，Nussenzweig MC ，Steinman RM ，Liu K ... -  《-》