Till Röhn

Vaccination against IL‐17 suppresses autoimmune arthritis and encephalomyelitis

Interleukin 17 is a T cell‐derived cytokine that induces the release of pro‐inflammatory mediators in a wide range of cell types. Recently, a subset of IL‐17‐producing T helper cells (Th17) distinct from Th1 and Th2 cells has been described, which constitutes a new T cell polarization state. Aberrant Th17 responses and overexpression of IL‐17 have been implicated in a number of autoimmune disorders including rheumatoid arthritis and multiple sclerosis. Molecules blocking IL‐17 such as IL‐17‐specific monoclonal antibodies have proved to be effective in ameliorating disease in animal models. Hitherto, active immunization targeting IL‐17 is an untried approach. Herein we explore the potential of neutralizing IL‐17 by active immunization using virus‐like particles conjugated with recombinant IL‐17 (IL‐17‐VLP). Immunization with IL‐17‐VLP induced high levels of anti‐IL‐17 antibodies thereby overcoming natural tolerance, even in the absence of added adjuvant. Mice immunized with IL‐17‐VLP had lower incidence of disease, slower progression to disease and reduced scores of disease severity in both collagen‐induced arthritis and experimental autoimmune encephalomyelitis. Active immunization against IL‐17 therefore represents a novel therapeutic approach for the treatment of chronic inflammatory diseases.

Neutralization of IL-17 by active vaccination inhibits IL-23-dependent autoimmune myocarditis

The most common reason for heart failure in young adults is dilated cardiomyopathy often resulting from myocarditis. Clinical studies and animal models provide evidence that an autoimmune response against heart myosin is the underlying reason for the disease. IL‐12 has been suggested to play a key role in development of experimental autoimmune myocarditis (EAM), as IL‐12p40 and IL‐12Rβ1 knockouts are protected from disease. In this study, we have compared IL‐12p40–/– mice, IL‐12p35–/– mice and mice treated with a neutralizing IL‐23 antibody in EAM and found that in fact IL‐23, not IL‐12, is responsible for inflammatory heart disease. However, these cytokines appear to have redundant activity for priming and expansion of autoreactive CD4 T cells, as specific T cell proliferation was only defective in the absence of both cytokines. IL‐23 has been suggested to promote a pathogenic IL‐17‐producing T cell population. We targeted IL‐17 by capitalizing on an active vaccination approach that effectively breaks B cell tolerance. Neutralization of IL‐17 reduced myocarditis and heart autoantibody responses, suggesting that IL‐17 is the critical effector cytokine responsible for EAM. Thus, targeting of IL‐23 and IL‐17 by passive and active vaccination strategies holds promise as a therapeutic approach to treat patients at risk for development of dilated cardiomyopathy.

Transport of Streptococcus pneumoniae Capsular Polysaccharide in MHC Class II Tubules

Bacterial capsular polysaccharides are virulence factors and are considered T cell–independent antigens. However, the capsular polysaccharide Sp1 from Streptococcus pneumoniae serotype 1 has been shown to activate CD4+ T cells in a major histocompatibility complex (MHC) class II–dependent manner. The mechanism of carbohydrate presentation to CD4+ T cells is unknown. We show in live murine dendritic cells (DCs) that Sp1 translocates from lysosomal compartments to the plasma membrane in MHCII-positive tubules. Sp1 cell surface presentation results in reduction of self-peptide presentation without alteration of the MHCII self peptide repertoire. In DM-deficient mice, retrograde transport of Sp1/MHCII complexes resulting in T cell–dependent immune responses to the polysaccharide in vitro and in vivo is significantly reduced. The results demonstrate the capacity of a bacterial capsular polysaccharide antigen to use DC tubules as a vehicle for its transport as an MHCII/saccharide complex to the cell surface for the induction of T cell activation. Furthermore, retrograde transport requires the functional role of DM in self peptide–carbohydrate exchange. These observations open new opportunities for the design of vaccines against microbial encapsulated pathogens.

A Virus-Like Particle-Based Anti-Nerve Growth Factor Vaccine Reduces Inflammatory Hyperalgesia: Potential Long-Term Therapy for Chronic Pain

Chronic pain resulting from inflammatory and neuropathic disorders causes considerable economic and social burden. For a substantial proportion of patients, conventional drug treatments do not provide adequate pain relief. Consequently, novel approaches to pain management, involving alternative targets and new therapeutic modalities compatible with chronic use, are being sought. Nerve growth factor (NGF) is a major mediator of chronic pain. Clinical testing of NGF antagonists is ongoing, and clinical proof of concept has been established with a neutralizing mAb. Active immunization, with the goal of inducing therapeutically effective neutralizing autoreactive Abs, is recognized as a potential treatment option for chronic diseases. We have sought to determine if such a strategy could be applied to chronic pain by targeting NGF with a virus-like particle (VLP)-based vaccine. A vaccine comprising recombinant murine NGF conjugated to VLPs from the bacteriophage Qβ (NGFQβ) was produced. Immunization of mice with NGFQβ induced anti-NGF–specific IgG Abs capable of neutralizing NGF. Titers could be sustained over 1 y by periodic immunization but declined in the absence of boosting. Vaccination with NGFQβ substantially reduced hyperalgesia in collagen-induced arthritis or postinjection of zymosan A, two models of inflammatory pain. Long-term NGFQβ immunization did not change sensory or sympathetic innervation patterns or induce cholinergic deficits in the forebrain, nor did it interfere with blood-brain barrier integrity. Thus, autovaccination targeting NGF using a VLP-based approach may represent a novel modality for the treatment of chronic pain.

Vaccines against non-communicable diseases.

Chronic non-communicable diseases (NCDs) are increasingly recognized as the major cause of morbidity and mortality worldwide. Effective, affordable and broadly accessible medicines for their treatment are much sought after. Therapeutic B-cell vaccines aim at inducing neutralizing auto-reactive antibodies against important mediators of such diseases. Numerous animal models have demonstrated that active immunotherapy can induce disease-modifying levels of auto-antibodies. Recent findings from clinical trials have indicated that self-reactive antibodies can also be readily induced in humans; therapeutic efficacy, however, has not always been achieved. To date, clinical experience with vaccines against self-molecules is limited. Choice of the right target, proper vaccine design, optimal vaccine dose and regimen remain the major challenges to achieve clinical efficacy and safety for this novel class of biotherapeutics.

IL-17A/F-signaling does not contribute to the initial phase of mucosal inflammation triggered by S. Typhimurium.

Salmonella enterica subspecies 1 serovar Typhimurium (S. Typhimurium) causes diarrhea and acute inflammation of the intestinal mucosa. The pro-inflammatory cytokines IL-17A and IL-17F are strongly induced in the infected mucosa but their contribution in driving the tissue inflammation is not understood. We have used the streptomycin mouse model to analyze the role of IL-17A and IL-17F and their cognate receptor IL-17RA in S. Typhimurium enterocolitis. Neutralization of IL-17A and IL-17F did not affect mucosal inflammation triggered by infection or spread of S. Typhimurium to systemic sites by 48 h p.i. Similarly, Il17ra−/− mice did not display any reduction in infection or inflammation by 12 h p.i. The same results were obtained using S. Typhimurium variants infecting via the TTSS1 type III secretion system, the TTSS1 effector SipA or the TTSS1 effector SopE. Moreover, the expression pattern of 45 genes encoding chemokines/cytokines (including CXCL1, CXCL2, IL-17A, IL-17F, IL-1α, IL-1β, IFNγ, CXCL-10, CXCL-9, IL-6, CCL3, CCL4) and antibacterial molecules was not affected by Il17ra deficiency by 12 h p.i. Thus, in spite of the strong increase in Il17a/Il17f mRNA in the infected mucosa, IL-17RA signaling seems to be dispensable for eliciting the acute disease. Future work will have to address whether this is attributable to redundancy in the cytokine signaling network.

Protective effect of a germline, IL-17-neutralizing antibody in murine models of autoimmune inflammatory disease.

Monoclonal antibodies (mAbs) inhibiting cytokines have recently emerged as new drug modalities for the treatment of chronic inflammatory diseases. Interleukin‐17 (IL‐17) is a T‐cell‐derived central mediator of autoimmunity. Immunization with Qβ‐IL‐17, a virus‐like particle based vaccine, has been shown to produce autoantibodies in mice and was effective in ameliorating disease symptoms in animal models of autoimmunity. To characterize autoantibodies induced by vaccination at the molecular level, we generated mouse mAbs specific for IL‐17 and compared them to germline Ig sequences. The variable regions of a selected hypermutated high‐affinity anti‐IL‐17 antibody differed in only three amino acid residues compared to the likely germline progenitor. An antibody, which was backmutated to germline, maintained a surprisingly high affinity (0.5 nM). The ability of the parental hypermutated antibody and the derived germline antibody to block inflammation was subsequently tested in murine models of multiple sclerosis (experimental autoimmune encephalomyelitis), arthritis (collagen‐induced arthritis), and psoriasis (imiquimod‐induced skin inflammation). Both antibodies were able to delay disease onset and significantly reduced disease severity. Thus, the mouse genome unexpectedly encodes for antibodies with the ability to functionally neutralize IL‐17 in vivo.

Melanoma cell necrosis facilitates transfer of specific sets of antigens onto MHC class II molecules of dendritic cells.

Vaccine strategies that target dendritic cells (DC) in order to elicit immunity against tumors are the subject of intense research. For the induction and maintenance of anti‐tumor immunity, CD4+ helper T cells are often required, which need to see appropriate MHC class II‐peptide complexes on DC. So far, it remained widely unclear what type of tumor cells can feed the MHC class II processing pathway of DC with what type of antigens. Here, we report that peptide loading onto MHC class II molecules of myeloid DC is facilitated by melanoma cells undergoing necrotic rather than apoptotic cell death. Importantly, the set of MHC class II‐associated peptides induced by necrotic tumor cells differed from those found upon engagement of apoptotic tumor cells. This may be due to the fact that only necrotic cells liberated heat shock proteins, which bind tumor‐derived peptides and thereby may promote processing by DC. The potential of DC to activate T cells was kinetically controlled through their antigen receptivity: CD4+ T cells were easily stimulated upon encountering antigen early in DC maturation, whereas antigen capture at later maturation stages favored activation of CD8+ T cells. These findings may aid in designing future vaccination strategies and in identifying novel tumor‐specific helper T cell antigens.