Preclinical safety and immunogenicity evaluation of a nonavalent PorA native outer membrane vesicle vaccine against serogroup B meningococcal disease.

BACKGROUND: An improved nonavalent PorA native outer membrane vesicle vaccine was developed with intrinsic adjuvating activity due to presence of less-toxic (lpxL1) LPS. In the present study, the safety and immunogenicity of this next-generation NonaMen vaccine were evaluated following repeated vaccination in rabbits and mice. METHODS: A repeated-dose toxicology study was performed in rabbits. Immunogenicity of next-generation NonaMen was evaluated by determining the serum bactericidal antibody (SBA) titers against meningococcal serogroup B strains containing several PorA subtypes. Release of the pro-inflammatory cytokine, interleukin-6 (IL-6), by the human monocytic cell line (MM6) was measured to estimate pyrogenic activity. RESULTS: No toxicologically relevant findings were noted in vaccinated rabbits receiving plain next-generation NonaMen. In agreement, next-generation NonaMen induced reduced amounts of the pro-inflammatory cytokine, IL-6, released by human monocyte cell line. In both rabbits and mice, next-generation NonaMen induced high SBA titers against all tested MenB strains regardless of whether or not aluminium phosphate adjuvant is used. CONCLUSIONS: The data suggest that next-generation NonaMen is a safe vaccine with the potential to develop a broadly protective immune response and encourage the start of the first clinical studies.

IL-8 as antibody therapeutic target in inflammatory diseases: reduction of clinical activity in palmoplantar pustulosis.

IL-8 is a chemokine that has been implicated in a number of inflammatory diseases involving neutrophil activation. HuMab 10F8 is a novel fully human mAb against IL-8, which binds a discontinuous epitope on IL-8 overlapping the receptor binding site, and which effectively neutralizes IL-8-dependent human neutrophil activation and migration. We investigated whether interference in the cytokine network by HuMab 10F8 might benefit patients suffering from palmoplantar pustulosis, a chronic inflammatory skin disease. Treatment of patients with HuMab 10F8 was well tolerated and significantly reduced clinical disease activity at all five endpoints, which included a >or=50% reduction in the formation of fresh pustules. IL-8 neutralization was monitored at the site of inflammation by assessing exudates of palmoplantar pustulosis lesions. HuMab 10F8 sequestered IL-8 in situ, as observed by rapid dose-dependent decreases of IL-8 concentrations immediately following Ab infusion. These data demonstrate a critical role for IL-8 in the pathophysiology of palmoplantar pustulosis. HuMab 10F8 is capable of interrupting IL-8 activity in vivo and represents a candidate for treatment of inflammatory diseases and other pathological conditions associated with IL-8 overproduction.

Identification and monitoring of effector and regulatory T cells during experimental arthritis based on differential expression of CD25 and CD134.

Major problems in the analysis of CD4+ effector cell and regulatory T cell (Treg) populations in an activated immune system are caused by the facts that both cell types can express CD25 and that the discriminatory marker forkhead box p3 can only be analyzed in nonviable (permeabilized) cells. Here, we show that CD134 (OX40) can be used as a discriminatory marker combined with CD25 to isolate and characterize viable CD4+ effector cells and Tregs. Before and during adjuvant arthritis in rats, coexpression of CD134 and CD25 identified activated Tregs consistently, as these T cells proliferated poorly to disease-associated antigens and were suppressive in vitro and in vivo. Depending on the time of isolation and location, CD4+ T cell populations expressing CD134 or CD25 contained effector/memory T cells. Analysis of the function, phenotype, and amount of the CD4+ T cell subsets in different lymph node stations revealed spatiotemporal differences in effector cell and Treg compartments during experimental arthritis.

CD134 as target for specific drug delivery to auto-aggressive CD4+ T cells in adjuvant arthritis.

T cells have an important role during the development of autoimmune diseases. In adjuvant arthritis, a model for rheumatoid arthritis, we found that the percentage of CD4+ T cells expressing the activation marker CD134 (OX40 antigen) was elevated before disease onset. Moreover, these CD134+ T cells showed a specific proliferative response to the disease-associated epitope of mycobacterial heat shock protein 60, indicating that this subset contains auto-aggressive T cells. We studied the usefulness of CD134 as a molecular target for immune intervention in arthritis by using liposomes coated with a CD134-directed monoclonal antibody as a drug targeting system. Injection of anti-CD134 liposomes subcutaneously in the hind paws of pre-arthritic rats resulted in targeting of the majority of CD4+CD134+ T cells in the popliteal lymph nodes. Furthermore, we showed that anti-CD134 liposomes bound to activated T cells were not internalized. However, drug delivery by these liposomes could be established by loading anti-CD134 liposomes with the dipalmitate-derivatized cytostatic agent 5'-fluorodeoxyuridine. These liposomes specifically inhibited the proliferation of activated CD134+ T cells in vitro, and treatment with anti-CD134 liposomes containing 5'-fluorodeoxyuridine resulted in the amelioration of adjuvant arthritis. Thus, CD134 can be used as a marker for auto-aggressive CD4+ T cells early in arthritis, and specific liposomal targeting of drugs to these cells via CD134 can be employed to downregulate disease development.

Identification of a CD4+CD25+ T cell subset committed in vivo to suppress antigen-specific T cell responses without additional stimulation.

Naturally occurring CD4+ regulatory T cells can be identified on the basis of expression of CD25 and suppression of T cell responses in vitro after TCR triggering. Here, we demonstrate that a CD134+ subset of CD4+CD25+ T cells in naive rats suppresses antigen-specific T cell responses in vitro without additional TCR stimulation. In contrast, CD4+CD25+CD134- regulatory T cells and total CD4+CD25+ regulatory T cells have suppressive activity only during simultaneous activation of responder and regulatory T cells or after in vitro pre-activation. Furthermore CD4+CD25+CD134+ T cells have a more activated phenotype than CD4+CD25+CD134- T cells, as based on the expression of CD62L, CD45RC, and MHC class II. We propose that the CD134+ regulatory T cells contain an in vivo activated and highly suppressive regulatory T cell subset. CD4+CD25+CD134+ T cells can be found in several compartments of the immune system, including spleen, lymph nodes, and blood. Interestingly though, the relative amounts of these cells within the CD4+ population and their CD134 expression levels are highest in mucosa-draining lymph nodes and lowest in blood. This suggests that the presence of CD4+CD25+CD134+ T cells indicates sites of active immune suppression.

Searching for the cartilage-associated mimicry epitope in adjuvant arthritis.

Adjuvant arthritis (AA) is a T cell mediated disease which can be induced in genetically susceptible rats by immunization with heat-killed Mycobacterium tuberculosis (Mt) suspended in incomplete Freund's adjuvant. The critical mycobacterial T cell epitope for the induction of AA was previously identified as residues 178-186 of the mycobacterial 65 kDa heat shock protein (Mt. hsp65(178-186)). It was suggested that the development of AA was due to molecular mimicry between a mycobacterial epitope and a cartilage-associated self-antigen. However, until now such cartilage-associated mimicry epitope has not been identified. In this study we designed a computer search profile to predict mimicry self-epitopes, and investigated whether one or more of these self-epitopes could serve as mimicry epitopes in AA. Although several of these self-epitopes were recognized by arthritogenic T cells, no cross-reactivity was found between T cells specific for these self-epitopes and Mt. hsp65(178-186) specific T cells.