Flt3L dependence helps define an uncharacterized subset of murine cutaneous dendritic cells.
ABSTRACT: Skin-derived dendritic cells (DCs) are potent antigen-presenting cells with critical roles in both adaptive immunity and tolerance to self. Skin DCs carry antigens and constitutively migrate to the skin-draining lymph nodes (LNs). In mice, Langerin-CD11b- dermal DCs are a low-frequency, heterogeneous, migratory DC subset that traffics to LNs (Langerin-CD11b- migDCs). Here, we build on the observation that Langerin-CD11b- migDCs are Fms-like tyrosine kinase 3 ligand (Flt3L) dependent and strongly Flt3L responsive, which may relate them to classical DCs. Examination of DC capture of FITC from painted skin, DC isolation from skin explant culture, and from the skin of CCR7 knockout mice, which accumulate migDCs, demonstrate these cells are cutaneous residents. Langerin-CD11b- Flt3L-responsive DCs are largely CD24(+) and CX3CR1(low) and can be depleted from Zbtb46-DTR mice, suggesting classical DC lineage. Langerin-CD11b- migDCs present antigen with equal efficiency to other DC subsets ex vivo, including classical CD8? cDCs and Langerin+CD103+ dermal DCs. Finally, transcriptome analysis suggests a close relationship with other skin DCs, and a lineage relationship with other classical DCs. This work demonstrates that Langerin- CD11b- dermal DCs, a previously overlooked cell subset, may be an important contributor to the cutaneous immune environment.
Project description:DCs are critical for initiating immunity. The current paradigm in vaccine biology is that DCs migrating from peripheral tissue and classical lymphoid-resident DCs (cDCs) cooperate in the draining LNs to initiate priming and proliferation of T cells. Here, we observe subcutaneous immunity is Fms-like tyrosine kinase 3 ligand (Flt3L) dependent. Flt3L is rapidly secreted after immunization; Flt3 deletion reduces T cell responses by 50%. Flt3L enhances global T cell and humoral immunity as well as both the numbers and antigen capture capacity of migratory DCs (migDCs) and LN-resident cDCs. Surprisingly, however, we find immunity is controlled by cDCs and actively tempered in vivo by migDCs. Deletion of Langerin(+) DC or blockade of DC migration improves immunity. Consistent with an immune-regulatory role, transcriptomic analyses reveals different skin migDC subsets in both mouse and human cluster together, and share immune-suppressing gene expression and regulatory pathways. These data reveal that protective immunity to protein vaccines is controlled by Flt3L-dependent, LN-resident cDCs.
Project description:CCR7 is regarded as an essential chemokine receptor for cutaneous dendritic cell (DC) migration into the regional lymph nodes. However, complete migratory inhibition cannot be obtained in CCR7-deficient mice, suggesting that there exist other chemokine receptors involved in this process. Initially, we found that CXCR4 was highly expressed on migrated cutaneous DCs and that its ligand, CXCL12, was detected in the LYVE-1(+) lymphatic vessels in the skin. FITC-induced cutaneous DC migration into the draining lymph nodes was impaired by the specific CXCR4 antagonist 4-F-Benzoyl-TN14003. Among FITC(+) cells, Langerin(+) Langerhans cells and Langerin(-) (dermal) dDC subsets were detected as CD11c(high+)CD11b(int+) cells and CD11c(high+)CD11b(high+) plus CD11c(low+)CD11b(int+) cells, respectively, both of which were suppressed by CXCR4 antagonist. Moreover, in vivo contact hypersensitivity response was impaired by CXCR4 antagonist administered during the sensitization phase. The in vitro proliferative response to dinitrobenzene sulfonic acid of sensitized lymph node cells was inhibited by CXCR4 antagonist treatment. These findings demonstrated that CXCL12-CXCR4 engagement on cutaneous DCs plays a crucial role in the initiation of skin immune response by enhancing cutaneous DC migration.
Project description:Dendritic cells (DCs) subsets differ in precursor cell of origin, functional properties, requirements for growth factors, and dependence on transcription factors. Lymphoid-tissue resident CD8?(+) conventional DCs (cDCs) and CD11b(low/-)CD103(+) non-lymphoid DCs are developmentally related, each being dependent on FMS-like tyrosine kinase 3 ligand (Flt3L), and requiring the transcription factors Batf3, Irf8, and Id2 for development. It was recently suggested that granulocyte/macrophage colony stimulating factor (GM-CSF) was required for the development of dermal CD11b(low/-)Langerin(+)CD103(+) DCs, and that this dermal DC subset was required for priming autoreactive T cells in experimental autoimmune encephalitis (EAE). Here, we compared development of peripheral tissue DCs and susceptibility to EAE in GM-CSF receptor deficient (Csf2rb(-/-)) and Batf3(-/-) mice. We find that Batf3-dependent dermal CD11b(low/-)Langerin(+) DCs do develop in Csf2rb(-/-) mice, but that they express reduced, but not absent, levels of CD103. Further, Batf3(-/-) mice lacking all peripheral CD11b(low/-) DCs show robust Th cell priming after subcutaneous immunization and are susceptible to EAE. Our results suggest that defective T effector priming and resistance to EAE exhibited by Csf2rb(-/-) mice does not result from the absence of dermal CD11b(low/-)Langerin(+)CD103(+) DCs.
Project description:Langerhans cells (LCs) constitute a subset of dendritic cells (DCs) that express the lectin langerin and that reside in their immature state in epidermis. Paradoxically, in mice permitting diphtheria toxin (DT)-mediated ablation of LCs, epidermal LCs reappeared with kinetics that lagged behind that of their putative progeny found in lymph nodes (LNs). Using bone marrow (BM) chimeras, we showed that a major fraction of the langerin(+), skin-derived DCs found in LNs originates from a developmental pathway that is independent from that of epidermal LCs. This pathway, the existence of which was unexpected, originates in the dermis and gives rise to langerin(+) dermal DCs (DDCs) that should not be confused with epidermal LCs en route to LNs. It explains that after DT treatment, some langerin(+), skin-derived DCs reappear in LNs long before LC-derived DCs. Using CD45 expression and BrdU-labeling kinetics, both LCs and langerin(+) DDCs were found to coexist in wild-type mice. Moreover, DT-mediated ablation of epidermal LCs opened otherwise filled niches and permitted repopulation of adult noninflammatory epidermis with BM-derived LCs. Our results stress that the langerin(+) DC network is more complex than originally thought and have implications for the development of transcutaneous vaccines and the improvement of humanized mouse models.
Project description:Langerhans cells (LCs) are antigen-presenting cells that reside in the epidermis of the skin and traffic to lymph nodes (LNs). The general role of these cells in skin immune responses is not clear because distinct models of LC depletion resulted in opposite conclusions about their role in contact hypersensitivity (CHS) responses. While comparing these models, we discovered a novel population of LCs that resides in the dermis and does not represent migrating epidermal LCs, as previously thought. Unlike epidermal LCs, dermal Langerin(+) dendritic cells (DCs) were radiosensitive and displayed a distinct cell surface phenotype. Dermal Langerin(+) DCs migrate from the skin to the LNs after inflammation and in the steady state, and represent the majority of Langerin(+) DCs in skin draining LNs. Both epidermal and dermal Langerin(+) DCs were depleted by treatment with diphtheria toxin in Lang-DTREGFP knock-in mice. In contrast, transgenic hLang-DTA mice lack epidermal LCs, but have normal numbers of dermal Langerin(+) DCs. CHS responses were abrogated upon depletion of both epidermal and dermal LCs, but were unaffected in the absence of only epidermal LCs. This suggests that dermal LCs can mediate CHS and provides an explanation for previous differences observed in the two-model systems.
Project description:Kidney dendritic cells (DCs) regulate nephritogenic T cell responses. Most kidney DCs belong to the CD11b+ subset and promote crescentic GN (cGN). The function of the CD103+ subset, which represents <5% of kidney DCs, is poorly understood. We studied the role of CD103+ DCs in cGN using several lines of genetically modified mice that allowed us to reduce the number of these cells. In all lines, we detected a reduction of FoxP3+ intrarenal regulatory T cells (Tregs), which protect against cGN. Mice lacking the transcription factor Batf3 had a more profound reduction of CD103+ DCs and Tregs than did the other lines used, and showed the most profound aggravation of cGN. The conditional reduction of CD103+ DC numbers by 50% in Langerin-DTR mice halved Treg numbers, which did not suffice to significantly aggravate cGN. Mice lacking the cytokine Flt3L had fewer CD103+ DCs and Tregs than Langerin-DTR mice but exhibited milder cGN than did Batf3-/- mice presumably because proinflammatory CD11b+ DCs were somewhat depleted as well. Conversely, Flt3L supplementation increased the number of CD103+ DCs and Tregs, but also of proinflammatory CD11b+ DCs. On antibody-mediated removal of CD11b+ DCs, Flt3L supplementation ameliorated cGN. Mechanistically, CD103+ DCs caused cocultured T cells to differentiate into Tregs and produced the chemokine CCL20, which is known to attract Tregs into the kidney. Our findings show that CD103+ DCs foster intrarenal FoxP3+ Treg accumulation, thereby antagonizing proinflammatory CD11b+ DCs. Thus, increasing CD103+ DC numbers or functionality might be advantageous in cGN.
Project description:Skin-resident dendritic cells (DCs) are well positioned to encounter cutaneous pathogens and are required for the initiation of adaptive immune responses. There are at least three subsets of skin DC- Langerhans cells (LC), Langerin(+) dermal DCs (dDCs), and classic dDCs. Whether these subsets have distinct or redundant function in vivo is poorly understood. Using a Candida albicans skin infection model, we have shown that direct presentation of antigen by LC is necessary and sufficient for the generation of antigen-specific T helper-17 (Th17) cells but not for the generation of cytotoxic lymphocytes (CTLs). In contrast, Langerin(+) dDCs are required for the generation of antigen specific CTL and Th1 cells. Langerin(+) dDCs also inhibited the ability of LCs and classic DCs to promote Th17 cell responses. This work demonstrates that skin-resident DC subsets promote distinct and opposing antigen-specific responses.
Project description:Overexpression of transforming growth factor beta-1 (TGF?1) in mouse epidermis causes cutaneous inflammation and keratinocyte hyperproliferation. Here we examined acute effects of TGF?1 overproduction by keratinocytes on skin dendritic cells (DCs). TGF?1 induction for 2 and 4 days increased the numbers and CD86 expression of B220(+) plasmacytoid DCs (pDCs) and CD207(+)CD103(+), CD207(-)CD103(-)CD11b(+), and CD207(-)CD103(-)CD11b(-) dermal DCs (dDCs) in skin-draining lymph nodes (SDLNs). The dermis of TGF?1-overexpressing mice had significantly more pDCs, CD207(+)CD103(+) dDCs, and CD207(-)CD11b(+) dDCs in the absence of increased dermal proliferation. Application of dye, tetramethyl rhodamine iso-thiocyanate (TRITC), in dibutylpthalate (DBP) solution after TGF?1 induction increased the numbers of TRITC(+)CD207(-) dDCs in SDLNs, and augmented TRITC/DBP-induced Langerhans cell (LC) migration 72 ?hours post TRITC treatment. Consistent with this, LC migration was increased in vitro by TGF?1 overexpression in skin explants and by exogenous TGF?1 in culture media. Transient TGF?1 induction during DNFB sensitization increased contact hypersensitivity responses by 1.5-fold. Thus, elevated epidermal TGF?1 alone is sufficient to alter homeostasis of multiple cutaneous DC subsets, and enhance DC migration and immune responses to contact sensitizers. These results highlight a role for keratinocyte-derived TGF?1 in DC trafficking and in the initiation of skin inflammation.
Project description:The chemokine receptor, CCR7, directs the migration of dendritic cells (DCs) from peripheral tissue to draining lymph nodes (LNs). However, it is unknown whether all pulmonary DCs possess migratory potential. Using novel Ccr7(gfp) reporter mice, we found that Ccr7 is expressed in CD103? and a CD14(med/lo) subset of CD11b(hi) classical (c)DCs but not in monocyte-derived (mo)DCs, including Ly-6C(hi)CD11b(hi) inflammatory DCs and CD14(hi)CD11b(hi) DCs. Consequently, cDCs migrated to lung-draining LNs but moDCs did not. Mice lacking the chemokine receptor, CCR2, also lacked inflammatory DCs in the lung after lipopolysaccharide inhalation but retained normal levels of migratory DCs. Conversely, the lungs of fms-like tyrosine kinase 3 ligand (Flt3L)-deficient mice lacked cDCs but retained moDCs, which were functionally mature but did not express Ccr7 and were uniformly non-migratory. Thus, the migratory properties of pulmonary DCs are determined by their developmental lineage.
Project description:Although dendritic cells (DCs) play an important role in mediating protection against influenza virus, the precise role of lung DC subsets, such as CD11b- and CD11b+ conventional DCs or plasmacytoid DCs (pDCs), in different lung compartments is currently unknown. Early after intranasal infection, tracheal CD11b-CD11chi DCs migrated to the mediastinal lymph nodes (MLNs), acquiring co-stimulatory molecules in the process. This emigration from the lung was followed by an accumulation of CD11b+CD11chi DCs in the trachea and lung interstitium. In the MLNs, the CD11b+ DCs contained abundant viral nucleoprotein (NP), but these cells failed to present antigen to CD4 or CD8 T cells, whereas resident CD11b-CD8+ DCs presented to CD8 cells, and migratory CD11b-CD8- DCs presented to CD4 and CD8 T cells. When lung CD11chi DCs and macrophages or langerin+CD11b-CD11chi DCs were depleted using either CD11c-diphtheria toxin receptor (DTR) or langerin-DTR mice, the development of virus-specific CD8+ T cells was severely delayed, which correlated with increased clinical severity and a delayed viral clearance. 120G8+ CD11cint pDCs also accumulated in the lung and LNs carrying viral NP, but in their absence, there was no effect on viral clearance or clinical severity. Rather, in pDC-depleted mice, there was a reduction in antiviral antibody production after lung clearance of the virus. This suggests that multiple DCs are endowed with different tasks in mediating protection against influenza virus.