Endogenous, or therapeutically induced, type I interferon responses differentially modulate Th1/Th17-mediated autoimmunity in the CNS

Different viruses trigger pattern recognition receptor systems, such as Toll-like receptors or cytosolic RIG-I like helicases (RLH), and thus induce early type I interferon (IFN-I) responses. Such responses may confer protection until adaptive immunity is activated to an extent that the pathogen can be eradicated. Interestingly, the same innate immune mechanisms that are relevant for early pathogen defense have a role in ameliorating experimental autoimmune encephalomyelitis (EAE), a rodent model of human multiple sclerosis. We and others found that mice devoid of a component of the IFN-I receptor (Ifnar1−/−) showed significantly enhanced autoimmune disease of the central nervous system (CNS). A detailed analysis revealed that in wild-type mice IFN-I triggering of myeloid cells was instrumental in reducing brain damage. A more recent study indicated that similar to Ifnar1−/− mice, RLH-signaling-deficient mice showed enhanced autoimmune disease of the CNS as well. Moreover, when peripherally treated with synthetic RLH ligands wild-type animals with EAE disease showed reduced clinical scores. Under such conditions, IFN-I receptor triggering of dendritic cells had a crucial role. The therapeutic effect of treatment with RLH ligands was associated with negative regulation of Th1 and Th17 T-cell responses within the CNS. These experiments are consistent with the hypothesis that spatiotemporal conditions of, and cell types involved in, disease-ameliorating IFN-I responses differ significantly, depending on whether they were endogenously induced in the context of EAE pathogenesis within the CNS or upon therapeutic RLH triggering in the periphery. It is attractive to speculate that RLH triggering represents a new strategy to treat multiple sclerosis by stimulating endogenous immunoregulatory IFN-I responses

Virus-induced Interferon α Production by a Dendritic Cell Subset in the Absence of Feedback Signaling In Vivo

An effective type I interferon (IFN-α/β) response is critical for the control of many viral infections. Here we show that in vesicular stomatitis virus (VSV)-infected mouse embryonic fibroblasts (MEFs) the production of IFN-α is dependent on type I IFN receptor (IFNAR) triggering, whereas in infected mice early IFN-α production is IFNAR independent. In VSV-infected mice type I IFN is produced by few cells located in the marginal zone of the spleen. Unlike other dendritic cell (DC) subsets, FACS®-sorted CD11cintCD11b−GR-1+ DCs show high IFN-α expression, irrespective of whether they were isolated from VSV-infected IFNAR-competent or -deficient mice. Thus, VSV preferentially activates a specialized DC subset presumably located in the marginal zone to produce high-level IFN-α largely independent of IFNAR feedback signaling

Preferential uptake of chitosan-coated PLGA nanoparticles by primary human antigen presenting cells

Biodegradable polymeric nanoparticles (NP) made from poly (lactid-co-glycolide) acid (PLGA) and chitosan (CS) hold promise as innovative formulations for targeted delivery. Since interactions of such NP with primary human immune cells have not been characterized, yet, here we assessed the effect of PLGA or CS-PLGA NP treatment on human peripheral blood mononuclear cells (PBMC), as well as on monocyte-derived DC (moDC). Amongst PBMC, antigen presenting cells (APC) showed higher uptake of both NP preparations than lymphocytes. Furthermore, moDC internalized CS-PLGA NP more efficiently than PLGA NP, presumably because of receptor-mediated endocytosis. Consequently, CS-PLGA NP were delivered mostly to endosomal compartments, whereas PLGA NP primarily ended up in lysosomes. Thus, CS-PLGA NP confer enhanced delivery to endosomal compartments of APC, offering new therapeutic options to either induce or modulate APC function and to inhibit pathogens that preferentially infect APC

A Soluble Version of Nipah Virus Glycoprotein G Delivered by Vaccinia Virus MVA Activates Specific CD8 and CD4 T Cells in Mice

Nipah virus (NiV) is an emerging zoonotic virus that is transmitted by bats to humans and to pigs, causing severe respiratory disease and often fatal encephalitis. Antibodies directed against the NiV-glycoprotein (G) protein are known to play a major role in clearing NiV infection and in providing vaccine-induced protective immunity. More recently, T cells have been also shown to be involved in recovery from NiV infection. So far, relatively little is known about the role of T cell responses and the antigenic targets of NiV-G that are recognized by CD8 T cells. In this study, NiV-G protein served as the target immunogen to activate NiV-specific cellular immune responses. Modified Vaccinia virus Ankara (MVA), a safety-tested strain of vaccinia virus for preclinical and clinical vaccine research, was used for the generation of MVA-NiV-G candidate vaccines expressing different versions of recombinant NiV-G. Overlapping peptides covering the entire NiV-G protein were used to identify major histocompatibility complex class I/II-restricted T cell responses in type I interferon receptor-deficient (IFNAR-/-) mice after vaccination with the MVA-NiV-G candidate vaccines. We have identified an H2-b-restricted nonamer peptide epitope with CD8 T cell antigenicity and a H2-b 15mer with CD4 T cell antigenicity in the NiV-G protein. The identification of this epitope and the availability of the MVA-NiV-G candidate vaccines will help to evaluate NiV-G-specific immune responses and the potential immune correlates of vaccine-mediated protection in the appropriate murine models of NiV-G infection. Of note, a soluble version of NiV-G was advantageous in activating NiV-G-specific cellular immune responses using these peptides

Personalized adoptive immunotherapy for patients with EBVassociated tumors and complications:Evaluation of novel naturally processed and presented EBV-derived T-cell epitopes

Morbidity and mortality of immunocompromised patients are increased by primary infection with or reactivation of Epstein-Barr virus (EBV), possibly triggering EBV+post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of EBV-specific cytotoxic T cells (EBV-CTLs) promises a non-toxic immunotherapy to effectively prevent or treat these complications. To improve immunotherapy and immunomonitoring this study aimed at identifying and evaluating naturally processed and presented HLA-A*03:01-restricted EBV-CTL epitopes as immunodominant targets. More than 15000 peptides were sequenced from EBV-immortalized B cells transduced with soluble HLA-A*03:01, sorted using different epitope prediction tools and eleven candidates were preselected. T2 and Flex-T peptide-binding and dissociation assays confirmed the stability of peptide-MHC complexes. Their immunogenicity and clinical relevance were evaluated by assessing the frequencies and functionality of EBV-CTLs in healthy donors (n> 10) and EBV+PTLD-patients (n= 5) by multimer staining, Eli- and FluoroSpot assays. All eleven peptides elicited EBV-CTL responses in the donors. Their clinical applicability was determined by small-scale T-cell enrichment using Cytokine Secretion Assay and immunophenotyping. Mixtures of these peptides when added to the EBV Consensus pool revealed enhanced stimulation and enrichment efficacy. These EBV-specific epitopes broadening the repertoire of known targets will improve manufacturing of clinically applicable EBV-CTLs and monitoring of EBV-specific T-cell responses in patients

Critical Role of Perforin-dependent CD8+ T Cell Immunity for Rapid Protective Vaccination in a Murine Model for Human Smallpox

Vaccination is highly effective in preventing various infectious diseases, whereas the constant threat of new emerging pathogens necessitates the development of innovative vaccination principles that also confer rapid protection in a case of emergency. Although increasing evidence points to T cell immunity playing a critical role in vaccination against viral diseases, vaccine efficacy is mostly associated with the induction of antibody responses. Here we analyze the immunological mechanism(s) of rapidly protective vaccinia virus immunization using mousepox as surrogate model for human smallpox. We found that fast protection against lethal systemic poxvirus disease solely depended on CD4 and CD8 T cell responses induced by vaccination with highly attenuated modified vaccinia virus Ankara (MVA) or conventional vaccinia virus. Of note, CD4 T cells were critically required to allow for MVA induced CD8 T cell expansion and perforin-mediated cytotoxicity was a key mechanism of MVA induced protection. In contrast, selected components of the innate immune system and B cell-mediated responses were fully dispensable for prevention of fatal disease by immunization given two days before challenge. In conclusion, our data clearly demonstrate that perforin-dependent CD8 T cell immunity plays a key role in MVA conferred short term protection against lethal mousepox. Rapid induction of T cell immunity might serve as a new paradigm for treatments that need to fit into a scenario of protective emergency vaccination

Role of Repetitive Antigen Patterns for Induction of Antibodies Against Antibodies

Antibody responses against antibodies, such as rheumatoid factors, are found in several immunopathological diseases and may play a role in disease pathogenesis. Experience shows that they are usually difficult to induce experimentally. Antibodies specific for immunoglobulin constant regions (anti-allotypic) or for variable regions (anti-idiotypic) have been investigated in animal models; the latter have even been postulated to regulate antibody and T cell responses via network-like interactions. Why and how such anti-antibodies are induced during autoimmune diseases, has remained largely unclear. Because repetitively arranged epitopes in a paracrystalline structure of a viral envelope cross-link B cell receptors efficiently to induce a prompt T-independent IgM response, this study used immune complexes containing viruses or bacteria to evaluate the role of antigen pattern for induction of anti-antibody responses. We present evidence that antibodies bound to strictly ordered, but not to irregularly arranged, antigens dramatically enhance induction of anti-antibodies, already after a single immunization and without using adjuvants. The results indicate a novel link between anti-antibody responses and infectious agents, and suggest a similar role for repetitive self-antigens such as DNA or collagen involved in chronic immunopathological diseases