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

Restoring the Balance between Pro-Inflammatory and Anti-Inflammatory Cytokines in the Treatment of Rheumatoid Arthritis: New Insights from Animal Models

Rheumatoid arthritis (RA) and other autoimmune inflammatory diseases are examples of imbalances within the immune system (disrupted homeostasis) that arise from the effects of an accumulation of environmental and habitual insults over a lifetime, combined with genetic predispositions. This review compares current immunotherapies-(1) disease-modifying anti-rheumatic drugs (DMARDs) and (2) Janus kinase (JAK) inhibitors (jakinibs)-to a newer approach-(3) therapeutic vaccines (using the LEAPS vaccine approach). The Ligand Epitope Antigen Presentation System (LEAPS) therapies are capable of inhibiting ongoing disease progression in animal models. Whereas DMARDs ablate or inhibit specific proinflammatory cytokines or cells and jakinibs inhibit the receptor activation cascade for expression of proinflammatory cytokines, the LEAPS therapeutic vaccines specifically modulate the ongoing antigen-specific, disease-driving, proinflammatory T memory cell responses. This decreases disease presentation and changes the cytokine conversation to decrease the expression of inflammatory cytokines (IL-17, IL-1(α or β), IL-6, IFN-γ, TNF-α) while increasing the expression of regulatory cytokines (IL-4, IL-10, TGF-β). This review refocuses the purpose of therapy for RA towards rebalancing the immune system rather than compromising specific components to stop disease. This review is intended to be thought provoking and look forward towards new therapeutic modalities rather than present a final definitive report.

Vaccination by Two DerG LEAPS Conjugates Incorporating Distinct Proteoglycan (PG, Aggrecan) Epitopes Provides Therapy by Different Immune Mechanisms in a Mouse Model of Rheumatoid Arthritis

Rheumatoid arthritis (RA) can be initiated and driven by immune responses to multiple antigenic epitopes including those in cartilage proteoglycan (PG, aggrecan) and type II collagen. RA is driven by T helper 1 (Th1) or Th17 pro-inflammatory T cell responses. LEAPS (Ligand Epitope Antigen Presentation System) DerG peptide conjugate vaccines were prepared using epitopes from PG that elicit immune responses in RA patients: epitope PG70 (DerG-PG70, also designated CEL-4000) and the citrullinated form of another epitope (PG275Cit). The LEAPS peptides were administered alone or together in Seppic ISA51vg adjuvant to mice with PG G1 domain-induced arthritis (GIA), a mouse model of RA. Each of these LEAPS peptides and the combination modulated the inflammatory response and stopped the progression of arthritis in the GIA mouse model. Despite having a therapeutic effect, the DerG-PG275Cit vaccine did not elicit significant antibody responses, whereas DerG-PG70 (alone or with DerG-PG275Cit) induced both therapy and antibodies. Spleen T cells from GIA mice, vaccinated with the DerG LEAPS peptides, preferentially produced anti-inflammatory (IL-4 and IL-10) rather than pro-inflammatory (IFN-γ or IL-17) cytokines in culture. Similarly, cytokines secreted by CD4+ cells of unvaccinated GIA mice, differentiated in vitro to Th2 cells and treated with either or both DerG vaccine peptides, exhibited an anti-inflammatory (IL-4, IL-10) profile. These results suggest that the two peptides elicit different therapeutic immune responses by the immunomodulation of disease-promoting pro-inflammatory responses and that the combination of the two LEAPS conjugates may provide broader epitope coverage and, in some cases, greater efficacy than either conjugate alone.

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.

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.

An attenuated herpes simplex virus type 1 (HSV1) encoding the HIV-1 Tat protein protects mice from a deadly mucosal HSV1 challenge

Herpes simplex virus types 1 and 2 (HSV1 and HSV2) are common infectious agents in both industrialized and developing countries. They cause recurrent asymptomatic and/or symptomatic infections, and life-threatening diseases and death in newborns and immunocompromised patients. Current treatment for HSV relies on antiviral medications, which can halt the symptomatic diseases but cannot prevent the shedding that occurs in asymptomatic patients or, consequently, the spread of the viruses. Therefore, prevention rather than treatment of HSV infections has long been an area of intense research, but thus far effective anti-HSV vaccines still remain elusive. One of the key hurdles to overcome in anti-HSV vaccine development is the identification and effective use of strategies that promote the emergence of Th1-type immune responses against a wide range of epitopes involved in the control of viral replication. Since the HIV1 Tat protein has several immunomodulatory activities and increases CTL recognition of dominant and subdominant epitopes of heterologous antigens, we generated and assayed a recombinant attenuated replication-competent HSV1 vector containing the tat gene (HSV1-Tat). In this proof-of-concept study we show that immunization with this vector conferred protection in 100% of mice challenged intravaginally with a lethal dose of wild-type HSV1. We demonstrate that the presence of Tat within the recombinant virus increased and broadened Th1-like and CTL responses against HSV-derived T-cell epitopes and elicited in most immunized mice detectable IgG responses. In sharp contrast, a similarly attenuated HSV1 recombinant vector without Tat (HSV1-LacZ), induced low and different T cell responses, no measurable antibody responses and did not protect mice against the wild-type HSV1 challenge. These findings strongly suggest that recombinant HSV1 vectors expressing Tat merit further investigation for their potential to prevent and/or contain HSV1 infection and dissemination.

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.

Intranasal immunization in mice with non-ionic surfactants vesicles containing HSV immunogens: a preliminary study as possible vaccine against genital herpes

The purpose of this study was to investigate the potential of intranasal immunization with non-ionic surfactant vesicles (NISV) containing either the secretory recombinant form of glycoprotein B (gBs) of herpes simplex virus type 1 or a related polylysine reach peptides (DTK) for induction of protective immunity against genital herpes infection in mice. NISV were prepared by lipid film hydration method. The mean diameter of vesicles was around 390 nm for DTK-containing NISV (DTK-NISV) and 320 nm for gB1s-containing NISV (gB1s-NISV). The encapsulation efficiency of the molecules was comprised between 57% and 70%. After 7-14 day NISV maintained stable dimensions and a drug encapsulation higher than 48%. We showed that intranasal immunization with gB1s-NISV induces gB-specific IgG antibody and lymphoproliferative responses, whereas vaccination with DTK-NISV was not able to generate a gB-specific immune response. Our results indicate that vaccination of BALB/c mice with gB1s-NISV induced Th1 responses, as characterized by increased titre of IG2a in plasma and IFN-production in CD4+ splenic cells. Intranasal immunization with gB1s-NISV could elicit 90% (almost complete) protection against a heterologous lethal vaginal challenge with herpes simplex virus type 2. These data may have implications for the development of a mucosal vaccine against genital herpes.

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.

Activation of NF-κB in CD8+ dendritic cells Ex Vivo by the γ134.5 null mutant correlates with immunity against herpes simplex virus 1

The γ(1)34.5 protein of herpes simplex viruses (HSV) is essential for virulence. Accordingly, an HSV mutant lacking γ(1)34.5 is attenuated in vivo. Despite its vaccine potential, the mechanism by which the γ(1)34.5 null mutant triggers protective immunity is unknown. In this report we show that vaccination with the γ(1)34.5 null mutant protects against lethal challenge from wild-type virus via IκB kinase in dendritic cells (DCs), which sense virus-associated molecular patterns. Unlike mock-treated DCs, DCs primed with the γ(1)34.5 null mutant ex vivo mediate resistance to wild-type HSV after adoptive transfer into naïve mice. Furthermore, the γ(1)34.5 null mutant activates IκB kinase, which facilitates p65/RelA phosphorylation and nuclear translocation, resulting in DC maturation. While unable to produce infectious virus in DCs, this mutant virus expresses early and late genes. In its abortive infection, the γ(1)34.5 null mutant induces protective immunity more effectively in CD8(+) DCs than in CD8(-) DCs. This is mirrored by a higher level of interleukin-6 (IL-6) and IL-12 secretion by CD8(+) DCs than CD8(-) DCs. Remarkably, inhibition of p65/RelA phosphorylation or nuclear translocation in CD8(+) DCs disrupts protective immunity. These results suggest that engagement of the γ(1)34.5 null mutant with CD8(+) DCs elicits innate immunity to activate NF-κB, which translates into protective immunity.

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.

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

LEAPS (ligand epitope antigen presentation system) vaccines consist of a peptide containing a major histocompatibility antigen binding peptide conjugated to an immune cell binding ligand (ICBL) such as the 'J' peptide from beta-2-microglobulin. Treatment of monocytes, monocytes plus GMCSF, or monocytes plus GMCSF and IL4 with JgD (containing a peptide from gD of herpes simplex virus type 1) or JH (with a peptide from HIV p17 gag protein) was sufficient to promote their maturation into Interleukin 12 producing dendritic cells. JgD-dendritic cells supported allotypic activation of T cells to produce Th1-related cytokines.