Maturation of dendritic cell precursors into IL12-producing DCs by J-LEAPS immunogens

Lessons from next generation influenza vaccines for inflammatory disease therapies

Lessons can be learned for treating inflammatory diseases such as rheumatoid arthritis (RA) from next generation approaches for development of universal influenza vaccines. Immunomodulation of inflammatory diseases, rather than ablation of cytokine or cellular responses, can address the root cause of the disease and provide potential cure. Like influenza, there are different antigenic 'strains' and inflammatory T cell responses, Th1 or Th17, that drive each person's disease. As such, next generation vaccine-like antigen specific therapies for inflammatory diseases can be developed but will need to be customized to the patient depending upon the antigen and T cell response that is driving the disease.

Why Don't We Have a Vaccine Against Autoimmune Diseases? - A Review

This review examines some of the reasons why we don't have a vaccine against autoimmune diseases and highlights the progress that has been made. Many autoimmune diseases, such as rheumatoid arthritis (RA), multiple sclerosis (MS) and type 1 diabetes (T1D), are driven by autoimmune T cell responses. Unlike vaccines for most infectious diseases, which elicit antibody responses, are intended for immuno-naive individuals and considered preventative, a vaccine for an autoimmune disease must be therapeutic and resolve or control the on-going autoimmune response and condition in the diseased host. Despite these differences, many of the same considerations for infectious disease vaccines must also be addressed to develop a therapeutic vaccine for autoimmune diseases. The disease initiator/triggers, antigens and autoantigens, nature of the immunopathogenic and protective/therapeutic immune response will be compared for infectious and autoimmune diseases as will approaches for developing vaccines including formulations, animal models and indicators of success. The rationale for a therapeutic vaccine for RA will be discussed in greater detail with a relatively limited discussion of T1D, MS and other autoimmune diseases.

An epitope-specific DerG-PG70 LEAPS vaccine modulates T cell responses and suppresses arthritis progression in two related murine models of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune joint disease maintained by aberrant immune responses involving CD4+ T helper (Th)1 and Th17 cells. In this study, we tested the therapeutic efficacy of Ligand Epitope Antigen Presentation System (LEAPS™) vaccines in two Th1 cell-driven mouse models of RA, cartilage proteoglycan (PG)-induced arthritis (PGIA) and PG G1-domain-induced arthritis (GIA). The immunodominant PG peptide PG70 was attached to a DerG or J immune cell binding peptide, and the DerG-PG70 and J-PG70 LEAPS vaccines were administered to the mice after the onset of PGIA or GIA symptoms. As indicated by significant decreases in visual and histopathological scores of arthritis, the DerG-PG70 vaccine inhibited disease progression in both PGIA and GIA, while the J-PG70 vaccine was ineffective. Splenic CD4+ cells from DerG-PG70-treated mice were diminished in Th1 and Th17 populations but enriched in Th2 and regulatory T (Treg) cells. In vitro spleen cell-secreted and serum cytokines from DerG-PG70-treated mice demonstrated a shift from a pro-inflammatory to an anti-inflammatory/regulatory profile. DerG-PG70 peptide tetramers preferentially bound to CD4+ T-cells of GIA spleen cells. We conclude that the DerG-PG70 vaccine (now designated CEL-4000) exerts its therapeutic effect by interacting with CD4+ cells, which results in an antigen-specific down-modulation of pathogenic T-cell responses in both the PGIA and GIA models of RA. Future studies will need to determine the potential of LEAPS vaccination to provide disease suppression in patients with RA.

LEAPS Vaccine Incorporating HER-2/neu Epitope Elicits Protection That Prevents and Limits Tumor Growth and Spread of Breast Cancer in a Mouse Model

The prototype J-LEAPS T cell vaccine for HER-2/neu breast cancer (J-HER) consists of the murine HER-2/neu_66-74 H-2^d CD8 T cell epitope covalently attached through a triglycine linker to the J-immune cell binding ligand (ICBL) (human β2 microglobulin_38-50 peptide). The J-ICBL was chosen for its potential to promote Th1/Tc1 responses. In this proof-of-concept study, the ability of J-HER to prevent or treat cancer was tested in the TUBO cell-challenged BALB/c mouse model for HER-2/neu-expressing tumors. The J-HER vaccine was administered as an emulsion in Montanide ISA-51 without the need for a more potent adjuvant. When administered as a prophylactic vaccination before tumor challenge, J-HER protected against tumor development for at least 48 days. Despite eliciting protection, antibody production in J-HER-immunized, TUBO-challenged mice was less than that in unimmunized mice. More importantly, therapeutic administration of J-HER one week after challenge with TUBO breast cancer cells limited the spread of the tumors and the morbidity and the mortality in the challenged mice. The ability to elicit responses that prevent spread of the TUBO tumor by J-HER suggests its utility as a neoimmunoadjuvant therapy to surgery. Individual or mixtures of J-LEAPS vaccines can be readily prepared to include different CD8 T cell epitopes to optimize tumor therapy and customize treatment for individuals with different HLA types.

Rheumatoid arthritis vaccine therapies: perspectives and lessons from therapeutic ligand epitope antigen presentation system vaccines for models of rheumatoid arthritis

The current status of therapeutic vaccines for autoimmune diseases is reviewed with rheumatoid arthritis as the focus. Therapeutic vaccines for autoimmune diseases must regulate or subdue responses to common self-antigens. Ideally, such a vaccine would initiate an antigen-specific modulation of the T-cell immune response that drives the inflammatory disease. Appropriate animal models and types of T helper cells and signature cytokine responses that drive autoimmune disease are also discussed. Interpretation of these animal models must be done cautiously because the means of initiation, autoantigens, and even the signature cytokine and T helper cell (Th1 or Th17) responses that are involved in the disease may differ significantly from those in humans. We describe ligand epitope antigen presentation system vaccine modulation of T-cell autoimmune responses as a strategy for the design of therapeutic vaccines for rheumatoid arthritis, which may also be effective in other autoimmune conditions.

Antigen-activated dendritic cells ameliorate influenza A infections

Influenza A viruses cause significant morbidity and mortality worldwide. There is a need for alternative or adjunct therapies, as resistance to currently used antiviral drugs is emerging rapidly. We tested ligand epitope antigen presentation system (LEAPS) technology as a new immune-based treatment for influenza virus infection in a mouse model. Influenza-J-LEAPS peptides were synthesized by conjugating the binding ligand derived from the β2-microglobulin chain of the human MHC class I molecule (J-LEAPS) with 15 to 30 amino acid-long peptides derived from influenza virus NP, M, or HA proteins. DCs were stimulated with influenza-J-LEAPS peptides (influenza-J-LEAPS) and injected intravenously into infected mice. Antigen-specific LEAPS-stimulated DCs were effective in reducing influenza virus replication in the lungs and enhancing survival of infected animals. Additionally, they augmented influenza-specific T cell responses in the lungs and reduced the severity of disease by limiting excessive cytokine responses, which are known to contribute to morbidity and mortality following influenza virus infection. Our data demonstrate that influenza-J-LEAPS-pulsed DCs reduce virus replication in the lungs, enhance survival, and modulate the protective immune responses that eliminate the virus while preventing excessive cytokines that could injure the host. This approach shows promise as an adjunct to antiviral treatment of influenza virus infections.

Dendritic cell-based vaccines: barriers and opportunities

Dendritic cells (DCs) have several characteristics that make them an ideal vehicle for tumor vaccines, and with the first US FDA-approved DC-based vaccine in use for the treatment of prostate cancer, this technology has become a promising new therapeutic option. However, DC-based vaccines face several barriers that have limited their effectiveness in clinical trials. A major barrier includes the activation state of the DC. Both DC lineage and maturation signals must be selected to optimize the antitumor response and overcome immunosuppressive effects of the tumor microenvironment. Another barrier to successful vaccination is the selection of target antigens that will activate both CD8(+) and CD4(+) T cells in a potent, immune-specific manner. Finally, tumor progression and immune dysfunction limit vaccine efficacy in advanced stages, which may make DC-based vaccines more efficacious in treating early-stage disease. This review underscores the scientific basis and advances in the development of DC-based vaccines, focuses on current barriers to success and highlights new research opportunities to address these obstacles.

LEAPS therapeutic vaccines as antigen specific suppressors of inflammation in infectious and autoimmune diseases

The L.E.A.P.S.(™) (Ligand Epitope Antigen Presentation System) technology platform has been used to develop immunoprotective and immunomodulating small peptide vaccines for infectious and autoimmune diseases. Several products are currently in various stages of development, at the pre-clinical stage (in animal challenge efficacy studies). Vaccine peptides can elicit protection of animals from lethal viral (herpes simplex virus [HSV-1] and influenza A) infection or can block the progression of autoimmune diseases (e.g. rheumatoid arthritis as in the collagen induced arthritis (CIA] or experimental autoimmune myocarditis (EAM) models). L.E.A.P.S. technology is a novel T-cell immunization technology that enables the design and synthesis of non-recombinant, proprietary peptide immunogens. Combination of a small peptide that activates the immune system with another small peptide from a disease-related protein, thus a conjugate containing both an Immune Cell Binding Ligand (ICBL) and a disease specific epitope, which allows the L.E.A.P.S. vaccines to activate precursors to differentiate and become more mature cells that can initiate and direct appropriate T cell responses. As such, readily synthesized, defined immunogens can be prepared to different diseases and are likely to elicit protection or therapy as applicable in humans as they are in mice. L.E.A.P.S. vaccines have promise for the treatment of rheumatoid arthritis and other inflammatory diseases and for infections, such as influenza and HSV1. The protective responses are characterized as Th1 immune and immunomodulatory responses with increased IL-12p70 and IFN-γ (Th1 cytokines) but reduced inflammatory cytokines TNF-α, IL-1 and IL-17 (Th2 and Th17 cytokines) and concomitant changes in antibody subtypes. LEAPS immunogens have been used directly in vivo or as ex vivo activators of DC which are then administered to the host.

Dendritic cells the tumor microenvironment and the challenges for an effective antitumor vaccination

Many clinical trials have been carried out or are in progress to assess the therapeutic potential of dendritic-cell- (DC-) based vaccines on cancer patients, and recently the first DC-based vaccine for human cancer was approved by the FDA. Herewith, we describe the general characteristics of DCs and different strategies to generate effective antitumor DC vaccines. In recent years, the relevance of the tumor microenvironment in the progression of cancer has been highlighted. It has been shown that the tumor microenvironment is capable of inactivating various components of the immune system responsible for tumor clearance. In particular, the effect of the tumor microenvironment on antigen-presenting cells, such as DCs, does not only render these immune cells unable to induce specific immune responses, but also turns them into promoters of tumor growth. We also describe strategies likely to increase the efficacy of DC vaccines by reprogramming the immunosuppressive nature of the tumor microenvironment.

Myeloid dendritic cells in HIV-1 infection

PURPOSE OF REVIEW

Myeloid dendritic cells (mDCs) are pivotal players in HIV-1 infection. They promote transmission and spread and at the same time are critical for recognizing HIV-1 and initiating immune responses to fight infection. Notably, their immunostimulatory capabilities can be harnessed to design better HIV-1 vaccines. In this review, advances in these areas of mDC-HIV-1 interactions are summarized.

RECENT FINDINGS

New insights into HIV-1-induced dysfunction of mDCs and dysfunctional mDC effects on other cell types, as well as novel mechanisms of viral sensing by mDCs and their evasion by HIV-1, have been uncovered. These results emphasize the importance of mDCs in protection against HIV-1 infection. Targeting mDCs with vaccines and tailored adjuvants may improve the quality and anatomical location of elicited immune responses.

SUMMARY

Understanding the multiplicity of HIV-1-dendritic cell interactions together with the numerous advances in targeted therapy and vaccination will help in the rational design of approaches to treat and block infection.

J-LEAPS peptide and LEAPS dendritic cell vaccines

The J‐LEAPS vaccines contain a peptide from β‐2‐microglobulin covalently attached to disease‐related peptides of 8–30 amino acids which contain a T cell epitope. The J‐LEAPS vaccines can initiate a protective Th1 immune response or modulate an ongoing Th17 autoimmune response to the peptide. J‐LEAPS vaccines activate and direct the nature of the subsequent immune response by promoting the maturation of precursor cells into a unique type of dendritic cell that produces interleukin 12, but not IL‐1 or tumour necrosis factor, and presents the antigenic peptide to T cells. Adoptive transfer of JgD‐LEAPS dendritic cells, matured with an anti‐HSV‐1 vaccine, promoted antigen‐specific Th1 protection against lethal challenge with the virus. J‐LEAPS peptide immunogens and J‐LEAPS dendritic cell vaccines have potential applications for antimicrobial prevention and therapy, treatment of autoimmune diseases, and for cancer immunotherapy.

Immunization with DNA vaccine expressing herpes simplex virus type 1 gD and IL-21 protects against mouse herpes keratitis

The development of novel vaccines to eradicate herpes simplex virus (HSV) is a global public health priority. In this study, we developed a DNA vaccine expressing HSV-1 glycoprotein D (gD) and mouse interleukin-21(IL-21) and intramuscularly inoculated mice 3 times at 2-week intervals with a total of 300 ?g/mouse. Two weeks after the last immunization the specific antibody, splenocyte proliferative response to gD, IFN-? and IL-4 as well as the cytotoxic activities of splenocytes and natural killer (NK) cells were assayed. Immune protection against herpes keratitis was concurrently evaluated in the immunized mice after HSV-1 challenge of the mouse cornea. The results showed that the DNA vaccine pRSC-gD-IL-21 generated higher levels of antibody, IFN-? and IL-4, and enhanced the splenocyte proliferative response to gD as well as the cytotoxic activity of splenocytes and NK cells to target cells compared with the response in either the pRSC-gD or mock plasmid pRSC immunized mice. Importantly, the pRSC-gD-IL-21 ameliorated herpes keratitis severity and time course after corneal infection with HSV-1. The findings suggest that the DNA vaccine pRSC-gD-IL-21 may induce an immune response that can limit HSV-1 infection and development of herpes keratitis in the immunized mice.

J-LEAPS vaccines initiate murine Th1 responses by activating dendritic cells

The Ligand Epitope Antigen Presentation System (LEAPS) converts a peptide containing a T cell epitope as small as 8 amino acids into an immunogen and directs the nature of the subsequent response. Tandem synthesis of the J peptide (a peptide from the beta-2-microglobulin) with peptides of 15 or 30 amino acids from HSV-1 or HIV made them immunogenic and promoted Th1 immune responses. Immunization of A/J or C57BL/6 mice with J-LEAPS heteroconjugates containing an epitope from the HSV-1 glycoprotein D (JgD) or an epitope from the HIV gag protein (JH) emulsified with Seppic ISA51 induced increased levels of IL-12p70 by day 3 and increased levels of interferon gamma (IFN-gamma) on days 10 and 24. Interestingly, levels of IL-10, TNF-alpha, and IL-6 did not change. Neither the H nor the gD peptides alone elicited responses and only weak responses followed immunization with the J peptide. Bone marrow (BM) cells became CD86 and CD11c positive within 48 h of treatment with JgD or JH. JH or JgD treatment promoted IL-12p70 production and expression of CD8 denoting the maturation and activation of a subclass of myeloid DCs. Pure cultures of immature myeloid DCs also responded to JgD treatment, forming clusters, developing dendrites, and producing IL-12p70 within 24 h. The JH or JgD treated bone marrow cells (JgD-DC) were necessary and sufficient to activate splenic T cells to produce IFN-gamma and the JgD-DC provided an antigen specific booster response to T cells from JgD immunized mice. Adoptive transfer of JgD-DC was also sufficient to initiate protective antigen specific immunity from lethal challenge with HSV-1. The J-LEAPS vaccines appear to act as an adjuvant and immunogen on DC precursors in a unique manner to promote activation and maturation into IL-12p70 producing DCs which then can initiate sufficient Th1 immune responses to elicit protection without production of acute phase cytokines.