Gunther Spohn

Nrf2 is essential for cholesterol crystal-induced inflammasome activation and exacerbation of atherosclerosis.

Oxidative stress and inflammation — two components of the natural host response to injury — constitute important etiologic factors in atherogenesis. The pro‐inflammatory cytokine interleukin (IL)‐1 significantly enhances atherosclerosis, however, the molecular mechanisms of IL‐1 induction within the artery wall remain poorly understood. Here we have identified the oxidative stress‐responsive transcription factor NF‐E2‐related 2 (Nrf2) as an essential positive regulator of inflammasome activation and IL‐1‐mediated vascular inflammation. We show that cholesterol crystals, which accumulate in atherosclerotic plaques, represent an endogenous danger signal that activates Nrf2 and the NLRP3 inflammasome. The resulting vigorous IL‐1 response critically depended on expression of Nrf2, and Nrf2‐deficient apolipoprotein E (Apoe)−/− mice were highly protected against diet‐induced atherogenesis. Importantly, therapeutic neutralization of IL‐1α and IL‐1β reduced atherosclerosis in Nrf2+/−Apoe−/− but not in Nrf2−/−Apoe−/− mice, suggesting that the pro‐atherogenic effect of Nrf2‐signaling was primarily mediated by its permissive role in IL‐1 production. Our studies demonstrate a role for Nrf2 in inflammasome activation, and identify cholesterol crystals as disease‐relevant triggers of the NLRP3 inflammasome and potent pro‐atherogenic cytokine responses. These findings suggest a common pathway through which oxidative stress and metabolic danger signals converge and mutually perpetuate the chronic vascular inflammation that drives atherosclerosis.

A Virus-Like Particle-Based Vaccine Selectively Targeting Soluble TNF-α Protects from Arthritis without Inducing Reactivation of Latent Tuberculosis

Neutralization of the proinflammatory cytokine TNF-α by mAbs or soluble receptors represents an effective treatment for chronic inflammatory disorders such as rheumatoid arthritis, psoriasis, or Crohn’s disease. In this study, we describe a novel active immunization approach against TNF-α, which results in the induction of high titers of therapeutically active autoantibodies. Immunization of mice with virus-like particles of the bacteriophage Qβ covalently linked to either the entire soluble TNF-α protein (Qβ-C-TNF1–156) or a 20-aa peptide derived from its N terminus (Qβ-C-TNF4–23) yielded specific Abs, which protected from clinical signs of inflammation in a murine model of rheumatoid arthritis. Whereas mice immunized with Qβ-C-TNF1–156 showed increased susceptibility to Listeria monocytogenes infection and enhanced reactivation of latent Mycobacterium tuberculosis, mice immunized with Qβ-C-TNF4–23 were not immunocompromised with respect to infection with these pathogens. This difference was attributed to recognition of both transmembrane and soluble TNF-α by Abs elicited by Qβ-C-TNF1–156, and a selective recognition of only soluble TNF-α by Abs raised by Qβ-C-TNF4–23. Thus, by specifically targeting soluble TNF-α, Qβ-C-TNF4–23 immunization has the potential to become an effective and safe therapy against inflammatory disorders, which might overcome the risk of opportunistic infections associated with the currently available TNF-α antagonists.

Active immunization with IL‐1 displayed on virus‐like particles protects from autoimmune arthritis

IL‐1 is an important mediator of inflammation and a major cause of tissue damage in rheumatoid arthritis (RA). Therapeutic administration of recombinant IL‐1 receptor antagonist (IL‐1Ra) is efficacious in reducing clinical symptoms of disease, but suffers from several drawbacks, including the need for frequent administrations of large amounts. Here, we show that immunization of mice with either IL‐1α or IL‐1β chemically cross‐linked to virus‐like particles (VLP) of the bacteriophage Qβ elicited a rapid and long‐lasting autoantibody response. The induced Ab efficiently neutralized the binding of the respective IL‐1 molecules to their receptors in vitro and their pro‐inflammatory activities in vivo. In the collagen‐induced arthritis model, both vaccines strongly protected mice from inflammation and degradation of bone and cartilage. Moreover, immunization with either vaccine showed superior efficacy than daily administrations of high amounts of IL‐1Ra. In the T and B cell‐independent collagen Ab transfer model, immunization with the IL‐1β vaccine strongly protected from arthritis, whereas immunization with the IL‐1α vaccine had no effect. Our results suggest that active immunization with IL‐1α, and especially IL‐1β conjugated to Qβ VLP, might become an efficacious and cost‐effective new treatment option for RA and other systemic IL‐1‐dependent inflammatory disorders.

A VLP-based vaccine targeting domain III of the West Nile virus E protein protects from lethal infection in mice.

BackgroundSince its first appearance in the USA in 1999, West Nile virus (WNV) has spread in the Western hemisphere and continues to represent an important public health concern. In the absence of effective treatment, there is a medical need for the development of a safe and efficient vaccine. Live attenuated WNV vaccines have shown promise in preclinical and clinical studies but might carry inherent risks due to the possibility of reversion to more virulent forms. Subunit vaccines based on the large envelope (E) glycoprotein of WNV have therefore been explored as an alternative approach. Although these vaccines were shown to protect from disease in animal models, multiple injections and/or strong adjuvants were required to reach efficacy, underscoring the need for more immunogenic, yet safe DIII-based vaccines.ResultsWe produced a conjugate vaccine against WNV consisting of recombinantly expressed domain III (DIII) of the E glycoprotein chemically cross-linked to virus-like particles derived from the recently discovered bacteriophage AP205. In contrast to isolated DIII protein, which required three administrations to induce detectable antibody titers in mice, high titers of DIII-specific antibodies were induced after a single injection of the conjugate vaccine. These antibodies were able to neutralize the virus in vitro and provided partial protection from a challenge with a lethal dose of WNV. Three injections of the vaccine induced high titers of virus-neutralizing antibodies, and completely protected mice from WNV infection.ConclusionsThe immunogenicity of DIII can be strongly enhanced by conjugation to virus-like particles of the bacteriophage AP205. The superior immunogenicity of the conjugate vaccine with respect to other DIII-based subunit vaccines, its anticipated favourable safety profile and low production costs highlight its potential as an efficacious and cost-effective prophylaxis against WNV.

Protection against Osteoporosis by Active Immunization with TRANCE/RANKL Displayed on Virus-Like Particles

TNF-related activation-induced cytokine (TRANCE), also known as receptor activator of NF-κB ligand (RANKL), is the key molecule responsible for the bone loss observed in osteoporosis. Passive administration of osteoprotegerin, the soluble decoy receptor of TRANCE/RANKL, is efficient in blocking disease progression, but may not find widespread clinical use due to patient compliance problems and the expected high costs. In this study, we describe an efficient, safe, and potentially cost-effective active immunization strategy against TRANCE/RANKL. We show in mice that immunization with TRANCE/RANKL covalently linked to virus-like particles can overcome the natural tolerance of the immune system toward self proteins and produce high levels of specific Abs without the addition of any adjuvant. Serum Abs of immunized mice neutralized TRANCE/RANKL activity in vitro and were highly active in preventing bone loss in a mouse model of osteoporosis. Active immunization against TRANCE/RANKL was essentially reversible and did not produce any measurable immunosuppressive side effects, underscoring its potential as a new therapeutic approach to the treatment of human bone-degenerative disorders.

Exploiting viral properties for the rational design of modern vaccines

A major challenge for the future is the development of effective vaccines against chronic infections and the application of therapeutic immunization to the treatment of noninfectious diseases, such as cancer, allergy and autoimmune disorders. In recent years, many of the immunological principles governing the immune response to infectious agents have been clarified and can now be exploited for the rational design of new and better vaccines. As an elucidative example, this review will describe the key immunogenic determinants of viruses and discuss how they can be harnessed for the development of tailor-made vaccines against a wide array of human diseases.

Blocking IL-1α but not IL-1β increases susceptibility to chronic Mycobacterium tuberculosis infection in mice.

IL-1α and IL-1β are potent inflammatory cytokines and important mediators of immune responses to intracellular pathogens such as Mycobacterium tuberculosis (Mtb). Here, we investigated the role of IL-1α and IL-1β during chronic Mtb infection and spontaneous reactivation in mice. For long-term neutralization of IL-1α, IL-1β or both, mice were immunized with virus-like particles (VLPs) displaying either of the cytokines, inducing strong and long-lasting neutralizing IgG responses. Blocking of IL-1α but not of IL-1β resulted in increased susceptibility to chronic infection with Mtb. Neutralizing either IL-1α or IL-1β alone did not lead to increased reactivation of latent tuberculosis. The generation of antibodies neutralizing both IL-1α and IL-1β simultaneously, did not influence weight gain during Mtb reactivation and the slight increase in pulmonary bacillary counts were not significant when compared to control-immunized group. Thus, the results suggest that IL-1α is the major mediator of the IL-1RI-dependent and protective innate immune responses to Mtb in mice.

A recombinant influenza a virus expressing domain III of west nile virus induces protective immune responses against influenza and west nile virus

West Nile virus (WNV) continues to circulate in the USA and forms a threat to the rest of the Western hemisphere. Since methods for the treatment of WNV infections are not available, there is a need for the development of safe and effective vaccines. Here, we describe the construction of a recombinant influenza virus expressing domain III of the WNV glycoprotein E (Flu-NA-DIII) and its evaluation as a WNV vaccine candidate in a mouse model. FLU-NA-DIII-vaccinated mice were protected from severe body weight loss and mortality caused by WNV infection, whereas control mice succumbed to the infection. In addition, it was shown that one subcutaneous immunization with 105 TCID50 Flu-NA-DIII provided 100% protection against challenge. Adoptive transfer experiments demonstrated that protection was mediated by antibodies and CD4+T cells. Furthermore, mice vaccinated with FLU-NA-DIII developed protective influenza virus-specific antibody titers. It was concluded that this vector system might be an attractive platform for the development of bivalent WNV-influenza vaccines.

Preclinical efficacy and safety of an anti-IL-1β vaccine for the treatment of type 2 diabetes

Neutralization of the inflammatory cytokine interleukin-1β (IL-1β) is a promising new strategy to prevent the β-cell destruction, which leads to type 2 diabetes. Here, we describe the preclinical development of a therapeutic vaccine against IL-1β consisting of a detoxified version of IL-1β chemically cross-linked to virus-like particles of the bacteriophage Qβ. The vaccine was well tolerated and induced robust antibody responses in mice, which neutralized the biological activity of IL-1β, as shown both in cellular assays and in challenge experiments in vivo. Antibody titers were long lasting but reversible over time and not associated with the development of potentially harmful T cell responses against IL-1β. Neutralization of IL-1β by vaccine-induced antibodies had no influence on the immune responses of mice to Listeria monocytogenes and Mycobacterium tuberculosis. In a diet-induced model of type 2 diabetes, immunized mice showed improved glucose tolerance, which was mediated by improved insulin secretion by pancreatic β-cells. Hence, immunization with IL-1β conjugated to virus-like particles has the potential to become a safe, efficacious, and cost-effective therapy for the prevention and long-term treatment of type 2 diabetes.

Development of an Interleukin-1β Vaccine in Patients with Type 2 Diabetes

Interleukin-1β (IL-1β) is a key cytokine involved in inflammatory illnesses including rare hereditary diseases and common chronic inflammatory conditions as gout, rheumatoid arthritis, and type 2 diabetes mellitus, suggesting reduction of IL-1β activity as new treatment strategy. The objective of our study was to assess safety, antibody response, and preliminary efficacy of a novel vaccine against IL-1β. The vaccine hIL1bQb consisting of full-length, recombinant IL-1β coupled to virus-like particles was tested in a preclinical and clinical, randomized, placebo-controlled, double-blind study in patients with type 2 diabetes. The preclinical simian study showed prompt induction of IL-1β-specific antibodies upon vaccination, while neutralizing antibodies appeared with delay. In the clinical study with 48 type 2 diabetic patients, neutralizing IL-1β-specific antibody responses were detectable after six injections with doses of 900 µg. The development of neutralizing antibodies was associated with higher number of study drug injections, lower baseline body mass index, improvement of glycemia, and C-reactive protein (CRP). The vaccine hIL1bQb was safe and well-tolerated with no differences regarding adverse events between patients receiving hIL1bQb compared to placebo. This is the first description of a vaccine against IL-1β and represents a new treatment option for IL-1β-dependent diseases such as type 2 diabetes mellitus (ClinicalTrials.gov NCT00924105).