Exosome-driven transfer of tumor-associated Pioneer Translation Products (TA-PTPs) for the MHC class I cross-presentation pathway.

Cellular immune reactions against non-self-epitopes require activation of cytotoxic CD8+ T-cells via cross-presentation of MHC class I-restricted peptides by professional antigen presenting cells (pAPCs), with the consequent detection and elimination of cells expressing the same antigens via the endogenous (direct) pathway. The source of peptides for the endogenous pathway is constituted of alternative mRNA translation products; however, it is still unclear which source of peptides is used for cross-presentation. Furthermore, the presentation of non-canonical translation products, produced during a non-conventional translation event, on class I molecules of tumor cells has been reported but how these peptides are generated, presented to pAPCs, and their capacity to stimulate CD8+ T cells is still not known. Here, we report that pioneer translation peptides (PTPs) derived from intron or exon pre-mRNAs can serve as tumor-associated antigens (TA-PTPs) and are delivered from the producing tumor cells to pAPCs via exosomes where they are processed by the cytosolic pathway. Injection of TA-PTPs and tumor-derived exosomes efficiently induce CD8+ T-cell proliferation and prevent tumor growth in mice. Our results show that TA-PTPs represent an efficient source of antigenic peptides for CD8+ T cell activation and that full-length proteins are not required for cross-presentation. These findings can have interesting implications for generating tolerance and for designing vectors to generate vaccines.

Targeting VEGF-A with a vaccine decreases inflammation and joint destruction in experimental arthritis.

OBJECTIVES: Inflammation and angiogenesis are two tightly linked processes in arthritis, and therapeutic targeting of pro-angiogenic factors may contribute to control joint inflammation and synovitis progression. In this work, we explored whether vaccination against vascular endothelial growth factor (VEGF) ameliorates collagen-induced arthritis (CIA). METHODS: Anti-VEGF vaccines were heterocomplexes consisting of the entire VEGF cytokine (or a VEGF-derived peptide) linked to the carrier protein keyhole limpet hemocyanin (KLH). Two kinds of vaccines were separately tested in two independent experiments of CIA. In the first, we tested a kinoid of the murine cytokine VEGF (VEGF-K), obtained by conjugating VEGF-A to KLH. For the second, we selected two VEGF-A-derived peptide sequences to produce heterocomplexes (Vpep1-K and Vpep2-K). DBA/1 mice were immunized with either VEGF-K, Vpep1-K, or Vpep2-K, before CIA induction. Clinical and histological scores of arthritis, anti-VEGF, anti-Vpep Ab titers, and anti-VEGF Abs neutralizing capacity were determined. RESULTS: Both VEGF-K and Vpep1-K significantly ameliorated clinical arthritis scores and reduced synovial inflammation and joint destruction at histology. VEGF-K significantly reduced synovial vascularization. None of the vaccines reduced anti-collagen Ab response in mice. Both VEGF-K and Vpep1-K induced persistently high titers of anti-VEGF Abs capable of inhibiting VEGF-A bioactivity. CONCLUSION: Vaccination against the pro-angiogenic factor VEGF-A leads to the production of anti-VEGF polyclonal Abs and has a significant anti-inflammatory effect in CIA. Restraining Ab response to a single peptide sequence (Vpep1) with a peptide vaccine effectively protects immunized mice from joint inflammation and destruction.

Modulation of anti-tumor necrosis factor alpha (TNF-α) antibody secretion in mice immunized with TNF-α kinoid.

Tumor necrosis factor alpha (TNF-α) blockade is an effective treatment for patients with TNF-α-dependent chronic inflammatory diseases, such as rheumatoid arthritis, Crohn's disease, and psoriasis. TNF-α kinoid, a heterocomplex of human TNF-α and keyhole limpet hemocyanin (KLH) (TNF-K), is an active immunotherapy targeting TNF-α. Since the TNF-K approach is an active immunization, and patients receiving this therapy also receive immunosuppressant treatment, we evaluated the effect of some immunosuppressive drugs on the generation of anti-TNF-α antibodies produced during TNF-K treatment. BALB/c mice were injected intramuscularly with TNF-K in ISA 51 adjuvant. Mice were also injected intraperitoneally with one of the following: phosphate-buffered saline, cyclophosphamide, methylprednisolone, or methotrexate. Anti-TNF-α and anti-KLH antibody levels were assessed by enzyme-linked immunosorbent assay and the anti-TNF-α neutralizing capacity of sera by L929 bioassay. Our results showed that current treatments used in rheumatoid arthritis, such as methylprednisolone and methotrexate, do not significantly alter anti-TNF-α antibody production after TNF-K immunization. In contrast, the administration of cyclophosphamide (200 mg/kg) after immunization significantly reduced anti-TNF-α antibody titers and their neutralizing capacity.

Active immunization against IL-23p19 improves experimental arthritis.

INTRODUCTION: IL-23 is a pro-inflammatory cytokine essential for the differentiation of Th17 lymphocytes, a subtype of T lymphocyte implied in auto-immunity. IL-23 shares a subunit with IL-12, IL-12/23p40, and comprises a specific subunit, IL-23p19. We previously demonstrated that active immunization against entire TNF-α and against peptides of IL-1ß was protective in animal models of rheumatoid arthritis. The aim of this study was to evaluate the effect of peptide-based vaccines targeting the IL-23p19 subunit in collagen-induced arthritis (CIA). METHODS: Using bioinformatics, the murine IL-23p19 subunit was modeled and two peptides were defined in the receptor interacting domain. Each peptide was coupled to keyhole limpet hemocyanin (KLH) to obtain two vaccines IL23-K1 and IL23-K2. Both vaccines were used for immunizations in incomplete Freund adjuvant (IFA) in groups of DBA/1 mice. Control groups received KLH or PBS at the same dates. CIA was induced by two subcutaneous injections of bovine type II collagen (CIIb), and the development of disease assessed during the next two months. Anti-CIIb and anti-IL-23 antibody levels were assessed by ELISA. Pro- and anti-inflammatory cytokines mRNA were quantified by qRT-PCR in the spleen and the synovium. T-cell populations in the spleen were evaluated by FACS analysis. RESULTS: The clinical scores showed that mice treated with IL23-K1 developed less arthritis than negative controls (p<0.05). Mice immunized with IL23-K1 produced more anti-IL-23 antibodies than those immunized with IL23-K2 (p<0.001). mRNA quantification showed that the IL23-K1 immunization led to an increase of IL-10 in the spleen (p<0.05 vs. KLH), without any effect on IL-17 level. Histological examination showed that IL23-K1 strongly protected against joint destruction and inflammation (p<0.01 vs. KLH and p<0.001 vs. PBS). T-cell populations in the spleen were not modified by IL-23 modulation. CONCLUSION: These data show that targeting IL-23p19 through a vaccination strategy is protective in CIA. This specific targeting of IL-23 might constitute a promising therapeutic approach to explore in rheumatoid arthritis.

Interleukin-23: a key cytokine in inflammatory diseases.

Interleukin-23 (IL-23) is a pro-inflammatory cytokine composed of two subunits, p19 and p40. The p40 subunit is shared with IL-12. IL-23 and IL-12 have different receptors and different effects. Whereas IL-12 induces development of Th1 cells, which produce interferon-γ, IL-23 is involved in differentiation of Th17 cells in a pro-inflammatory context and especially in the presence of TGF-ß and IL-6. Activated Th17 cells produce IL-17A, IL-17F, IL-6, IL-22, TNF-α, and GM-CSF. Inflammatory macrophages express IL-23R and are activated by IL-23 to produce IL-1, TNF-α, and IL-23 itself. These effects identify IL-23 as a central cytokine in autoimmunity and a highly promising treatment target for inflammatory diseases. IL-23 is found in the skin of patients with psoriasis, in the bowel wall of patients with chronic inflammatory bowel disease, and in synovial membrane of patients with rheumatoid arthritis. IL-23 is involved in osteoclastogenesis, independently from IL-17, via induction of RANKL expression. Debate continues to surround the role for IL-23 in the pathophysiology of inflammatory joint diseases (rheumatoid arthritis and spondyloarthritis). Ustekinumab, which inhibits IL-12 and IL-23 by blocking p40, has been found effective in cutaneous psoriasis and psoriatic arthritis, as well as in Crohn's disease. Treatments that specifically target IL-23 (antibodies to p19) are being developed.

Anti-cytokine vaccination in autoimmune diseases.

The concept of therapeutic vaccination represents a novel strategy of active immunotherapy that can be applied to autoimmune disease. The principle is to design molecules which can trigger an immune response, targeting a cytokine that is pathogenic and over-expressed in a given disease. The mostly available vaccines are an application of vaccination using either the self-protein coupled to a carrier (type I A), or a modified form of the protein engineered to include neo-epitopes (type I B). These approaches have been developed in models of several autoimmune diseases, mainly in TNFα-dependent diseases such as rheumatoid arthritis and Crohn's disease, but also in systemic lupus erythematosus, multiple sclerosis and myasthenia gravis. Clinical trials are in progress in rheumatoid arthritis, Crohn's disease and diabetes. The benefit/risk ratio of anti-cytokine vaccination is currently under study to further develop the vaccination strategies.