No abstract

T helper 17 (Th17) cells protect against infection but also promote inflammation and autoimmunity. Therefore, the factors that govern Th17 cell differentiation are of special interest. The CD27 and CD70 costimulatory pathway impeded Th17 effector cell differentiation and associated autoimmunity in a mouse model of multiple sclerosis. CD27 or CD70 deficiency exacerbated disease, whereas constitutive CD27 signaling strongly reduced disease incidence and severity. CD27 signaling did not impact master regulators of T helper cell lineage commitment but selectively repressed transcription of the key effector molecules interleukin-17 (IL-17) and the chemokine receptor CCR6 in differentiating Th17 cells. CD27 mediated this repression at least in part via the c-Jun N-terminal kinase (JNK) pathway that restrained IL-17 and CCR6 expression in differentiating Th17 cells. CD27 signaling also resulted in epigenetic silencing of the Il17a gene. Thus, CD27 costimulation via JNK signaling, transcriptional, and epigenetic effects suppresses Th17 effector cell function and associated pathological consequences.

Material Supplementary 9.DC1http://www.jimmunol.org/content/suppl/2010/11/03/jimmunol.100015References

TNF family member CD70 is the ligand of CD27, a costimulatory receptor that shapes effector and memory T cell pools. Tight control of CD70 expression is required to prevent lethal immunodeficiency. By selective transcription, CD70 is largely confined to activated lymphocytes and dendritic cells (DC). We show here that, in addition, specific intracellular routing controls its plasma membrane deposition. In professional antigen-presenting cells, such as DC, CD70 is sorted to late endocytic vesicles, defined as MHC class II compartments (MIIC). In cells lacking the machinery for antigen presentation by MHC class II, CD70 travels by default to the plasma membrane. Introduction of class II transactivator sufficed to reroute CD70 to MIIC. Vesicular trafficking of CD70 and MHC class II is coordinately regulated by the microtubule-associated dynein motor complex. We show that when maturing DC make contact with T cells in a cognate fashion, newly synthesized CD70 is specifically delivered via MIIC to the immunological synapse. Therefore, we propose that routing of CD70 to MIIC serves to coordinate delivery of the T cell costimulatory signal in time and space with antigen recognition.costimulation ͉ dendritic cell ͉ intracellular transport

Various cell types can produce the chemokine CXCL10 in response to IFN-γ stimulation. CXCL10 is generally viewed as a proinflammatory chemokine that promotes recruitment of CD8+ and Th1-type CD4+ effector T cells to infected or inflamed nonlymphoid tissues. We show that CXCL10 plays a role during CD8+ T cell priming in the mouse. Genome-wide expression profiling revealed the Cxcl10 gene as a target of CD27/CD70 costimulation in newly activated CD8+ T cells. CD27/CD70 costimulation is known to promote activated T cell survival, but CXCL10 did not affect survival or proliferation of primed CD8+ T cells in vitro. Accordingly, CXCL10 could not fully rescue CD27 deficiency in mice infected with influenza virus. Rather, CXCL10 acted as chemoattractant for other activated CD8+ T cells. It signaled downstream of CD27 in a paracrine fashion to promote generation of the CD8+ effector T cell pool in the Ag-draining lymph nodes. Consistently, CD8+ T cells required expression of the CXCL10 receptor CXCR3 for their clonal expansion in a CD27/CD70-dependent peptide-immunization model. Our findings indicate that CXCL10, produced by primed CD8+ T cells in response to CD27/CD70 costimulation, signals to other primed CD8+ T cells in the lymph node microenvironment to facilitate their participation in the CD8+ effector T cell pool.

SummaryCD70 is a TNF-related transmembrane molecule expressed by mature dendritic cells (DCs), which present antigens to T cells via major histocompatibility complex (MHC) molecules. In DCs, CD70 localizes with MHC class II molecules in late endosomal vesicles, known as MHC class II compartments (MIICs). MIICs are transported to the immune synapse when a DC contacts an antigen-specific CD4 + T cell. Consequently, MHC class II and CD70 are simultaneously exposed to the T cell. Thereby, T-cell activation via the antigen receptor and CD70-mediated co-stimulation are synchronized, apparently to optimize the proliferative response. We report here that the invariant chain (Ii), a chaperone known to transport MHC class II to MIICs, performs a similar function for CD70. CD70 was found to travel by default to the plasma membrane, whereas Ii coexpression directed it to late endosomes and/or lysosomes. In cells containing the MHC class II presentation pathway, CD70 localized to MIICs. This localization relied on Ii, since transport of CD70 from the Golgi to MIICs was impeded in Ii-deficient DCs. Biophysical and biochemical studies revealed that CD70 and Ii participate in an MHC-class-II-independent complex. Thus, Ii supports transport of both MHC class II and CD70 to MIICs and thereby coordinates their delivery to CD4 + T cells.

Immunotherapy of cancer has reached a mature and exciting stage. Clinical activity of monoclonal antibodies (mAb) against the T-cell inhibitory receptors CTLA-4 and PD-1 indicate that cancer patients often have latent tumour-specific T cells that can be mobilized by blocking these receptors. Activation of the T-cell costimulatory receptor CD27, a member of the TNF receptor family, provides another opportunity to promote cytotoxic T cell (CTL)-based anti-tumor immunity. To generate agonistic mAb against human (h)CD27, we used our unique B-cell selection and immortalization technology. Various novel anti-hCD27 mAb were generated and tested for their agonistic properties. We used in vitro read-out systems detecting CD27 (co-)stimulatory function on the basis of NF-κB activity, T cell division and survival. One mAb hCD27.15 (KD ∼1 nM), induced CD27 receptor activation (EC50 ∼1 nM) without the need of cross-linking. Similar to its natural ligand CD70, our hCD27.15 mAb showed bona fide costimulatory properties. hCD27.15 strongly promoted CD8+ T cell expansion under conditions of suboptimal T-cell receptor (TCR) stimulation. hCD27.15 did not stimulate T cell function in absence of TCR engagement. hCD27.15 mAb demonstrated different binding kinetics and a unique epitope, compared to other antibodies that depend on cross-linking to activate CD27. Importantly, hCD27.15 retained its agonistic properties when expressed as a human IgG1 or IgG4 chimera. hCD27.15 was shown to bind and activate primate CD27 with similar potency, providing a rationale for pre-clinical safety testing. In conclusion, to our knowledge we have developed the first mAb to hCD27 that mimics ligand function without the need for cross-linking. Data from mouse models strongly support the application of CD27 agonism to enhance CTL-based anti-tumor immunity, by promoting the generation and survival of CTL, as well as their memory function. We propose therefore that hCD27.15 mAb is a promising tool for cancer immunotherapy. Citation Format: Hans van Eenennaam, Elise Veraar, Winfried Mulder, Ellen Bastiaanssen, Lilian Driessen, David Lutje Hulsik, Paul Vink, Gerda van der Horst, Yanling Xiao, Jannie Borst, Andrea van Elsas. Development of an agonistic antibody against the human T-cell costimulatory receptor CD27 as a potential immunotherapeutic tool. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1246. doi:10.1158/1538-7445.AM2013-1246

A Proliferation Inducing Ligand (APRIL) is a TNF ligand that, via its receptors TACI and BCMA, is involved in both B cell physiology as well as in proliferation and survival of malignant B cells. To target APRIL-dependent stimulation of B cell cancers, we recently produced and characterized two monoclonal antagonistic anti-human APRIL antibodies called humanAPRIL.01A (hA.01A) and humanAPRIL.03A (hA.03A). In a first biochemical assay to validate their blocking activity, hA.01A was shown to fully prevent APRIL from binding to its receptors, whereas a substantial difference was detected for hA.03A, which inhibited APRIL binding to BCMA less efficiently than hA.01A. Epitope mapping subsequently revealed that hA.01A and hA.03A bind distinct sites on APRIL, which provided a structural rationale of their different blocking activities. Importantly, this differential inhibition profile can be used to functionally dissect BCMA and TACI-dependent signals and indicated that B cell survival and IgA production are regulated differently by these receptors. Primary CLL cultures were shown to be sensitive to APRIL neutralization using hA.01A. hA.01A also inhibited hyperplasia in a transgenic mouse model reminiscent of B-CLL. Altogether, these data indicate that hA.01A is a novel tool potentially useful for the targeted treatment of B cell-derived cancers such as B-CLL and Multiple Myeloma. Citation Format: Marco Guadagnoli, Katherine Cameron, Elise Veraar, Fiona Kimberley, Andrea van Elsas, Hans van Eenennaam, Jan Paul Medema. Characterization of anti-human APRIL monoclonal antibodies capable of inhibiting APRIL-dependent B cell function and hyperproliferation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5480. doi:10.1158/1538-7445.AM2013-5480