Batf3-dependent Dendritic Cells Research Articles

Batf3-Dependent Dendritic Cells Promote Optimal CD8 T Cell Responses against Respiratory Poxvirus Infection

Respiratory infection with vaccinia virus (VacV) elicits robust CD8+ T cell responses that play an important role in host resistance. In the lung, VacV encounters multiple tissue-resident antigen-presenting cell (APC) populations, but which cell plays a dominant role in priming of virus-specific CD8+ effector T cell responses remains poorly defined. We used Batf3-/- mice to investigate the impact of CD103+ and CD8α+ dendritic cell (DC) deficiency on anti-VacV CD8+ T cell responses. We found that Batf3-/- mice were more susceptible to VacV infection, exhibiting profound weight loss, which correlated with impaired accumulation of gamma interferon (IFN-γ)-producing CD8+ T cells in the lungs. This was largely due to defective priming since early in the response, antigen-specific CD8+ T cells in the draining lymph nodes of Batf3-/- mice expressed significantly reduced levels of Ki67, CD25, and T-bet. These results underscore a specific role for Batf3-dependent DCs in regulating priming and expansion of effector CD8+ T cells necessary for host resistance against acute respiratory VacV infection.IMPORTANCE During respiratory infection with vaccinia virus (VacV), a member of Poxviridae family, CD8+ T cells play important role in resolving the primary infection. Effector CD8+ T cells clear the virus by accumulating in the infected lungs in large numbers and secreting molecules such as IFN-γ that kill virally infected cells. However, precise cell types that regulate the generation of effector CD8+ T cells in the lungs are not well defined. Dendritic cells (DCs) are a heterogeneous population of immune cells that are recognized as key initiators and regulators of T-cell-mediated immunity. In this study, we reveal that a specific subset of DCs that are dependent on the transcription factor Batf3 for their development regulate the magnitude of CD8+ T cell effector responses in the lungs, thereby providing protection during pulmonary VacV infection.

A role for apoptotic and scavenger receptors in mediating antigen exchange between lymphatic endothelial cells and migratory dendritic cells

Abstract Antigen persistence following viral infection or vaccination occurs for several weeks after resolution of the inflammatory response. Lymphatic endothelial cells (LECs) capture and archive antigen, which is then transferred to migratory dendritic cells (DCs) and ultimately cross-presented to circulating memory T cells. Following vaccination, both BatF3-dependent and BatF3-independent DCs are needed for antigen exchange, while virus-associated antigen exchange is mediated only by BatF3-dependent DCs. Here, we explore the role of apoptotic and scavenger receptors in mediating this antigen capture and exchange between LECs and DCs. Cross-presentation of the DC-associated antigen to circulating T cells results in a memory pool with increased effector function and enhanced protective capacity. Overall, this work furthers our understanding of how persisting antigen impacts the CD8+ memory T cell response in both vaccine and infectious settings.

Synergistic anti-tumor efficacy of combined TLR3 and CD40 neoantigen vaccine requires Batf3-dependent dendritic cells

Abstract Therapeutic cancer vaccine therapy targeting neoantigens has yielded encouraging results, yet overall clinical responses to the treatment have thus far limited. A better understanding of the mechanisms that regulate priming of neoantigen-specific T cells is required to improve vaccine strategy. To this end, we used murine MC38 colon adenocarcinoma cells that harbor a single-epitope mutation within the Adpgk protein with the neo-epitope presented in MHC-I H-2Db molecules. MC38 tumor-bearing mice were treated with Adpgk mutant epitope in combination with toll-like receptor (TLR) 3 agonist, anti-CD40 agonist, or both. Therapeutic vaccination with the Adpgk mutant peptide combined with TLR3 and anti-CD40 agonists (TLR3/CD40) significantly improved survival compared with either TLR3 or CD40 stimulation alone. This was associated with expansion and differentiation of CD8+ T cells in the periphery as well as in the tumor microenvironment. Significantly increased terminally differentiated neoantigen-specific CD8+ T cells in blood and spleen were identified using the tetramer staining assay. Interestingly, frequency of neoantigen-specific CD8+ T cells in blood was inversely correlated with the tumor volume, suggesting epitope spreading and broadening T-cell clonality induced by TLR3/CD40 stimulation. Importantly, therapeutic efficacy of neoantigen/TLR3/CD40 vaccination was abrogated in Batf3 knockout mouse, suggesting Batf3-dependent dendritic cells play a critical role in priming adaptive immunity. These studies provide the rational basis for the use of combined TLR3 and CD40 agonists together as essential adjuvants to optimize vaccines designed to elicit therapeutic immunity against cancer neoantigens.

Enhanced anti-tumour immunity requires the interplay between resident and circulating memory CD8+ T cells

The goal of successful anti-tumoural immunity is the development of long-term protective immunity to prevent relapse. Infiltration of tumours with CD8+ T cells with a resident memory (Trm) phenotype correlates with improved survival. However, the interplay of circulating CD8+ T cells and Trm cells remains poorly explored in tumour immunity. Using different vaccination strategies that fine-tune the generation of Trm cells or circulating memory T cells, here we show that, while both subsets are sufficient for anti-tumour immunity, the presence of Trm cells improves anti-tumour efficacy. Transferred central memory T cells (Tcm) generate Trm cells following viral infection or tumour challenge. Anti-PD-1 treatment promotes infiltration of transferred Tcm cells within tumours, improving anti-tumour immunity. Moreover, Batf3-dependent dendritic cells are essential for reactivation of circulating memory anti-tumour response. Our findings show the plasticity, collaboration and requirements for reactivation of memory CD8+ T cells subsets needed for optimal tumour vaccination and immunotherapy.

DNA exonuclease Trex1 regulates radiotherapy-induced tumour immunogenicity

Radiotherapy is under investigation for its ability to enhance responses to immunotherapy. However, the mechanisms by which radiation induces anti-tumour T cells remain unclear. We show that the DNA exonuclease Trex1 is induced by radiation doses above 12–18 Gy in different cancer cells, and attenuates their immunogenicity by degrading DNA that accumulates in the cytosol upon radiation. Cytosolic DNA stimulates secretion of interferon-β by cancer cells following activation of the DNA sensor cGAS and its downstream effector STING. Repeated irradiation at doses that do not induce Trex1 amplifies interferon-β production, resulting in recruitment and activation of Batf3-dependent dendritic cells. This effect is essential for priming of CD8+ T cells that mediate systemic tumour rejection (abscopal effect) in the context of immune checkpoint blockade. Thus, Trex1 is an upstream regulator of radiation-driven anti-tumour immunity. Trex1 induction may guide the selection of radiation dose and fractionation in patients treated with immunotherapy.

Intratumoral delivery of inactivated modified vaccinia virus Ankara (iMVA) induces systemic antitumor immunity via STING and Batf3-dependent dendritic cells.

Advanced cancers remain a therapeutic challenge despite recent progress in targeted therapy and immunotherapy. Novel approaches are needed to alter the tumor immunosuppressive microenvironment and to facilitate the recognition of tumor antigens that leads to antitumor immunity. Poxviruses, such as modified vaccinia virus Ankara (MVA), have potential as immunotherapeutic agents. We show that infection of conventional dendritic cells (DCs) with heat- or ultraviolet-inactivated MVA leads to higher levels of interferon induction than MVA alone through the cGAS (cyclic guanosine monophosphate-adenosine monophosphate synthase)-STING cytosolic DNA-sensing pathway. Intratumoral injection of inactivated MVA (iMVA) was effective and generated adaptive antitumor immunity in murine melanoma and colon cancer models. iMVA-induced antitumor therapy was less effective in STING- or Batf3-deficient mice than in wild-type mice, indicating that both cytosolic DNA sensing and Batf3-dependent CD103+/CD8α+ DCs are essential for iMVA immunotherapy. The combination of intratumoral delivery of iMVA and systemic delivery of immune checkpoint blockade generated synergistic antitumor effects in bilateral tumor implantation models as well as in a unilateral large established tumor model. Our results suggest that inactivated vaccinia virus could be used as an immunotherapeutic agent for human cancers.

Distinct oxysterol requirements for positioning naïve and activated dendritic cells in the spleen.

Correct positioning of dendritic cells (DCs) is critical for efficient pathogen encounter and antigen presentation. Epstein-Barr virus-induced gene 2 (EBI2) has been identified as a chemoattractant receptor required for naïve CD4+DCIR2+ DC positioning in response to 7α,25-hydroxycholesterol (7α,25-HC). We now provide evidence that a second EBI2 ligand, 7α,27-HC, is involved in splenic DCIR2+ DC positioning and homeostasis. Cyp27a1, the enzyme uniquely required for 7α,27-HC synthesis, is expressed by stromal cells in the region of naïve DC localization. After activation, DCIR2+ DCs move into the T cell zone. We find that EBI2 is rapidly up-regulated in DCIR2+ DCs under certain activation conditions, and positioning at the B-T zone interface depends on EBI2. Under conditions of type I interferon induction, EBI2 ligand levels are elevated, causing activated DCIR2+ DCs to disperse throughout the T zone. Last, we provide evidence that oxysterol metabolism by Batf3-dependent DCs is important for EBI2-dependent positioning of activated DCIR2+ DCs. This work indicates that 7α,27-HC functions as a guidance cue in vivo and reveals a multitiered role for EBI2 in DC positioning. Deficiency in this organizing system results in defective CD4+ T cell responses.

Abscopal Effects of Radiotherapy Are Enhanced by Combined Immunostimulatory mAbs and Are Dependent on CD8 T Cells and Crosspriming.

Preclinical and clinical evidence indicate that the proimmune effects of radiotherapy can be synergistically augmented with immunostimulatory mAbs to act both on irradiated tumor lesions and on distant, nonirradiated tumor sites. The combination of radiotherapy with immunostimulatory anti-PD1 and anti-CD137 mAbs was conducive to favorable effects on distant nonirradiated tumor lesions as observed in transplanted MC38 (colorectal cancer), B16OVA (melanoma), and 4T1 (breast cancer) models. The therapeutic activity was crucially performed by CD8 T cells, as found in selective depletion experiments. Moreover, the integrities of BATF-3-dependent dendritic cells specialized in crosspresentation/crosspriming of antigens to CD8+ T cells and of the type I IFN system were absolute requirements for the antitumor effects to occur. The irradiation regimen induced immune infiltrate changes in the irradiated and nonirradiated lesions featured by reductions in the total content of effector T cells, Tregs, and myeloid-derived suppressor cells, while effector T cells expressed more intracellular IFNγ in both the irradiated and contralateral tumors. Importantly, 48 hours after irradiation, CD8+ TILs showed brighter expression of CD137 and PD1, thereby displaying more target molecules for the corresponding mAbs. Likewise, PD1 and CD137 were induced on tumor-infiltrating lymphocytes from surgically excised human carcinomas that were irradiated ex vivo These mechanisms involving crosspriming and CD8 T cells advocate clinical development of immunotherapy combinations with anti-PD1 plus anti-CD137 mAbs that can be synergistically accompanied by radiotherapy strategies, even if the disease is left outside the field of irradiation. Cancer Res; 76(20); 5994-6005. ©2016 AACR.

Intestinal Batf3-dependent dendritic cells are required for optimal antiviral T-cell responses in adult and neonatal mice.

Although we know a great deal about which types of dendritic cells (DCs) promote T-cell priming in the periphery, less is known about which DC subset(s) provoke antiviral responses within the gut. Here we report that conventional Zbtb46-dependent DCs were critically required for antiviral CD8+ T-cell responses against rotavirus (RV), the major cause of childhood gastroenteritis worldwide. Furthermore, we found that in adult mice, Batf3-dependent DCs were required for generating optimal RV-specific CD8+ T-cell responses. However, in contrast to mice that lack Zbtb46-dependent DCs, a significant amount of interferon gamma-producing RV-specific CD8+ T cells were still detected in the small intestine of RV-infected adult Batf3-/- mice, suggesting the existence of compensatory cross-presentation mechanisms in the absence of Batf3-dependent DCs. In contrast to adult mice, we found that Batf3-dependent DCs were absolutely required for generating RV-specific CD8+ T-cell responses in neonates. Loss of Batf3-dependent DCs also resulted in a skewed polyclonal CD4+ T-cell response in both adult and neonatal mice upon RV infection, although local and systemic RV-specific immunoglobulin A production kinetics and titers were unimpaired. Our results provide insights that inform early-life vaccination strategies against RV infection.

Abstract 4908: Cancer immunotherapy with immunomodulatory anti-CD137 and anti-PD-1 monoclonal antibodies requires Batf3-dependent dendritic cells

Abstract Weak and ineffective antitumor cytotoxic T lymphocyte (CTL) responses can be rescued by immunomodulatory monoclonal antibodies (mAbs) targeting PD-1 or CD137. Using Batf3-/- mice, which are defective for cross-presentation of cell-associated antigens, we show that Batf3-dependent dendritic cells (DCs) are essential for the response to therapy with anti-CD137 or anti-PD-1 mAbs. Batf3-/- mice failed to prime an endogenous CTL-mediated immune response toward tumor-associated antigens, including neoantigens. As a result, the immunomodulatory mAbs could not amplify any therapeutically functional immune response in these mice. Moreover, administration of systemic sFlt3L and local poly-ICLC enhanced DC-mediated cross-priming and synergized with anti-CD137- and anti-PD-1-mediated immunostimulation in tumor therapy against B16-OVA-derived melanomas, whereas this function was lost in Batf3-/- mice. These experiments show that cross-priming of tumor antigens by Flt3L- and Batf3-dependent DCs is crucial to the efficacy of immunostimulatory mAbs and represents a very attractive point of intervention to enhance their clinical antitumor effects. Citation Format: Alfonso R. Sánchez-Paulete, Francisco J. Cueto, María Martínez-López, Sara Labiano, Aizea Morales-Kastresana, Maria E. Rodríguez-Ruiz, Maria Jure-Kunkel, Arantza Azpilikueta, José I. Quetglas, David Sancho, Ignacio Melero. Cancer immunotherapy with immunomodulatory anti-CD137 and anti-PD-1 monoclonal antibodies requires Batf3-dependent dendritic cells. [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 4908.

Batf3-dependent dendritic cells impact T-cell responses differently between adult and neonatal mice in an intestinal viral infection.

Abstract The role of dendritic cells (DCs) in shaping the immunity against bacterial infections in the colon (e.g. Citrobacter rodentium) has been well investigated; however, what subset modulates the immune response against viral infections in the small bowel is less known. Rotavirus (RV) almost exclusively infects and replicates in the small intestinal villi resulting in both cellular and humoral adaptive immunity, and RV infection serves as a model to study the DC-elicited antiviral responses in adult and neonatal mice. Batf3−/− adult and neonatal mice lack CD103+CD11b− DCs in the small intestinal lamina propria (SILP) and displayed a delay in viral clearance. CD8+ T cells have a role in the resolution of primary RV infection, and indeed, we found that while no antigen-specific CD8+ T cell response was detected in the Batf3−/− neonatal mice, a residual CD8+ T cell response was observed in the Batf3−/− adult mice, suggesting compensatory antigen-presentation from other adult DC subsets in the SILP (such as CD103+CD11b+ DCs). In terms of the CD4+ T cell response, no Th1 response was found in adult Batf3-deficient or –sufficient mice, however, a robust Th1 response was present in neonatal mice which was dependent on Batf3, implying a requirement of CD103+CD11b−DCs for priming/maintaining a Th1 response only in the neonatal period. Both the local and systemic anti-RV IgA response was normal in adult Batf3−/− mice, however, neonatal Batf3−/− mice displayed a stronger systemic IgA response than littermate controls. Our results demonstrate a requirement for Batf3-dependent DCs in antiviral responses which differs between neonates and adults, and these results may shed light on vaccine design.

Cutting Edge: The RIG-I Ligand 3pRNA Potently Improves CTL Cross-Priming and Facilitates Antiviral Vaccination.

Protective immunity against intracellular pathogens involves the induction of robust CTL responses. Vaccination with protein Ags establishes such responses only when combined with immune-stimulatory adjuvants. In this study, we compared different adjuvants and identified triphosphate RNA (3pRNA) as especially effective at inducing CTL responses. 3pRNA sensing required IPS-1/MAVS signaling and induced type I IFN in plasmacytoid dendritic cells and macrophages, with the latter being more important for the adjuvant effect. Type I IFN acted on CD11c(+) cells, especially on CD8α(+) Batf3-dependent dendritic cells. Vaccination with OVA in combination with 3pRNA protected mice from a subsequent OVA-encoding adenovirus infection in a CD8(+) cell-dependent manner and more efficiently than other adjuvants. In summary, 3pRNA is a superior adjuvant for CTL activation and might be useful to facilitate antiviral immunization strategies.

Cancer Immunotherapy with Immunomodulatory Anti-CD137 and Anti-PD-1 Monoclonal Antibodies Requires BATF3-Dependent Dendritic Cells.

Weak and ineffective antitumor cytotoxic T lymphocyte (CTL) responses can be rescued by immunomodulatory mAbs targeting PD-1 or CD137. Using Batf3(-/-) mice, which are defective for cross-presentation of cell-associated antigens, we show that BATF3-dependent dendritic cells (DC) are essential for the response to therapy with anti-CD137 or anti-PD-1 mAbs. Batf3(-/-) mice failed to prime an endogenous CTL-mediated immune response toward tumor-associated antigens, including neoantigens. As a result, the immunomodulatory mAbs could not amplify any therapeutically functional immune response in these mice. Moreover, administration of systemic sFLT3L and local poly-ICLC enhanced DC-mediated cross-priming and synergized with anti-CD137- and anti-PD-1-mediated immunostimulation in tumor therapy against B16-ovalbumin-derived melanomas, whereas this function was lost in Batf3(-/-) mice. These experiments show that cross-priming of tumor antigens by FLT3L- and BATF3-dependent DCs is crucial to the efficacy of immunostimulatory mAbs and represents a very attractive point of intervention to enhance their clinical antitumor effects. Immunotherapy with immunostimulatory mAbs is currently achieving durable clinical responses in different types of cancer. We show that cross-priming of tumor antigens by BATF3-dependent DCs is a key limiting factor that can be exploited to enhance the antitumor efficacy of anti-PD-1 and anti-CD137 immunostimulatory mAbs.

Ablation of CD8α(+) dendritic cell mediated cross-presentation does not impact atherosclerosis in hyperlipidemic mice.

Clinical complications of atherosclerosis are almost exclusively linked to destabilization of the atherosclerotic plaque. Batf3-dependent dendritic cells specialize in cross-presentation of necrotic tissue-derived epitopes to directly activate cytolytic CD8 Tcells. The mature plaque (necrotic, containing dendritic cells and CD8 Tcells) could offer the ideal environment for cross-presentation, resulting in cytotoxic immunity and plaque destabilization. Ldlr−/− mice were transplanted with batf3−/− or wt bone marrow and put on a western type diet. Hematopoietic batf3 deficiency sharply decreased CD8α+ DC numbers in spleen and lymph nodes (>80%; P < 0,001). Concordantly, batf3−/− chimeras had a 75% reduction in OT-I cross-priming capacity in vivo. Batf3−/− chimeric mice did not show lower Tcell or other leukocyte subset numbers. Despite dampened cross-presentation capacity, batf3−/− chimeras had equal atherosclerosis burden in aortic arch and root. Likewise, batf3−/− chimeras and wt mice revealed no differences in parameters of plaque stability: plaque Tcell infiltration, cell death, collagen composition, and macrophage and vascular smooth muscle cell content were unchanged. These results show that CD8α+ DC loss in hyperlipidemic mice profoundly reduces cross-priming ability, nevertheless it does not influence lesion development. Taken together, we clearly demonstrate that CD8α+ DC-mediated cross-presentation does not significantly contribute to atherosclerotic plaque formation and stability.

Cutting Edge: Roles for Batf3-Dependent APCs in the Rejection of Minor Histocompatibility Antigen-Mismatched Grafts.

In transplantation, a major obstacle for graft acceptance in MHC-matched individuals is the mismatch of minor histocompatibility Ags. Minor histocompatibility Ags are peptides derived from polymorphic proteins that can be presented by APCs on MHC molecules. The APC subtype uniquely responsible for the rejection of minor Ag-mismatched grafts has not yet been identified. In this study, we examined graft rejection in three mouse models: 1) mismatch of male-specific minor Ags, 2) mismatch of minor Ags distinct from male-specific minor Ags, and 3) skin transplant. This study demonstrates that in the absence of pathogen-associated molecular patterns, Batf3-dependent dendritic cells elicit the rejection of cells and grafts expressing mismatched minor Ags. The implication of our findings in clinical transplantation may be significant, as minor Ag reactivity has been implicated in the pathogenesis of multiple allograft tissues.

Bone-Marrow-Resident NK Cells Prime Monocytes for Regulatory Function during Infection

Tissue-infiltrating Ly6C(hi) monocytes play diverse roles in immunity, ranging from pathogen killing to immune regulation. How and where this diversity of function is imposed remains poorly understood. Here we show that during acute gastrointestinal infection, priming of monocytes for regulatory function preceded systemic inflammation and was initiated prior to bone marrow egress. Notably, natural killer (NK) cell-derived IFN-γ promoted a regulatory program in monocyte progenitors during development. Early bone marrow NK cell activation was controlled by systemic interleukin-12 (IL-12) produced by Batf3-dependent dendritic cells (DCs) in the mucosal-associated lymphoid tissue (MALT). This work challenges the paradigm that monocyte function is dominantly imposed by local signals after tissue recruitment, and instead proposes a sequential model of differentiation in which monocytes are pre-emptively educated during development in the bone marrow to promote their tissue-specific function.

Batf3-dependent dendritic cells are essential for development of diabetes in the NOD strain of mouse (BA7P.145)

Abstract Little is known about the early events that instigate autoimmune diabetogenesis. To understand these initiating events, we examined the early antigen presenting cells (APCs) within the islets of Langerhans in the NOD mouse. Islets contain a set of resident macrophages that are long lived and positioned next to blood vessels. We found, concurrent with T cell entry, a small subset of CD103+ dendritic cells (DCs) belonging to the Batf3-dependent lineage of DCs entering the islets during the early stages of diabetes. These DCs increase in the islets over the course of the disease paralleling the increase of T cells. In order to further investigate the function of these DCs during diabetes, we backcrossed the Batf3 deficient mouse to the NOD strain. These Batf3 deficient NOD mice displayed no diabetes when followed for over a year. No lymphocytic infiltration into the islets, innate or adaptive, was observed during their lifetime. Further examination showed that antigens presented to CD8+ T cells were absent, in conjunction with a reduction in antigen presentation to CD4+ T cells, in the draining lymph nodes. Finally, NOD.Rag1-/- bone marrow reconstitution rescued the CD103+ DCs and T cell infiltration to the islets. The reconstitution illustrates that Batf3 deficient T cells were intrinsically capable of being diabetic and confirms the necessity of the CD103+ DC lineage in diabetogensis. In sum, the CD103+DC controls the initiation of autoimmune diabetes.

Double-edged sword: self-acquiring Batf3-dependent dendritic cell required for anti-tumor immunity and graft rejection (APP3P.104)

Abstract One of the major obstacles for the graft acceptance of tissue and organs is the mismatch of major and minor histocompatibility (H) antigens. Minor H antigens are peptides derived from polymorphic proteins and presented by antigen-presenting cells on major histocompatibility complex (MHC) molecules. Here we hypothesized that the self-acquiring, cross-presenting Batf3-dependent dendritic cell (DC) is responsible for minor-antigen graft rejection. Using three models of minor-antigen graft rejection: 1) male antigen 2) non-sex complex minor antigen and 3) skin organ transplant, we demonstrate that Batf3-dependent DCs are responsible for minor-antigen graft rejection. However, in the presence of a TLR7 ligand, the requirement for Batf3-dependent DCs is bypassed by shifting the functionality of Batf3-independent DCs to elicit minor-antigen graft rejection. Overall our study identifies the DC subtype responsible for minor-antigen graft rejection.

Effective treatment of allergic airway inflammation with Helicobacter pylori immunomodulators requires BATF3-dependent dendritic cells and IL-10.

The prevalence of allergic asthma and other atopic diseases has reached epidemic proportions in large parts of the developed world. The gradual loss of the human indigenous microbiota has been held responsible for this trend. The bacterial pathogen Helicobacter pylori is a constituent of the normal gastric microbiota whose presence has been inversely linked to allergy and asthma in humans and experimental models. Here we show that oral or i.p. tolerization with H. pylori extract prevents the airway hyperresponsiveness, bronchoalveolar eosinophilia, pulmonary inflammation, and Th2 cytokine production that are hallmarks of allergen-induced asthma in mice. Asthma protection is not conferred by extracts from other enteropathogens and requires a heat-sensitive H. pylori component and the DC-intrinsic production of IL-10. The basic leucine zipper ATF-like 3 (BATF3)-dependent CD103(+)CD11b(-) dendritic cell lineage is enriched in the lungs of protected mice and strictly required for protection. Two H. pylori persistence determinants, the γ-glutamyl-transpeptidase GGT and the vacuolating cytotoxin VacA, are required and sufficient for asthma protection and can be administered in purified form to prevent asthma. In conclusion, we provide preclinical evidence for the concept that the immunomodulatory properties of H. pylori can be exploited for tolerization strategies aiming to prevent allergen-induced asthma.

Batf3-Dependent Dendritic Cells in the Renal Lymph Node Induce Tolerance against Circulating Antigens

Although the spleen is a major site where immune tolerance to circulating innocuous antigens occurs, the kidney also contributes. Circulating antigens smaller than albumin are constitutively filtered and concentrated in the kidney and reach the renal lymph node by lymphatic drainage, where resident dendritic cells (DCs) capture them and induce tolerance of specific cytotoxic T cells through unknown mechanisms. Here, we found that the coinhibitory cell surface receptor programmed death 1 (PD-1) on cytotoxic T cells mediates to their tolerance. Renal lymph node DCs of the CD8(+) XCR1(+) subset, which depend on the transcription factor Batf3, expressed the PD-1 cognate ligand PD-L1. Batf3-dependent DCs in the renal lymph node presented antigen that had been concentrated in the kidney and used PD-L1 to induce apoptosis of cytotoxic T cells. In contrast, T cell tolerance in the spleen was independent of PD-1, PD-L1, and Batf3. In summary, these results clarify how the kidney/renal lymph node system tolerizes the immune system against circulating innocuous antigens.