Safety and immunogenicity of the group B streptococcus vaccine AlpN in a placebo-controlled double-blind phase 1 trial.

Group B streptococcus (GBS) is a leading cause of life-threatening neonatal infections and subsets of adverse pregnancy outcomes. Essentially all GBS strains possess one allele of the alpha-like protein (Alp) family. A maternal GBS vaccine, consisting of the fused N-terminal domains of the Alps αC and Rib (GBS-NN), was recently demonstrated to be safe and immunogenic in healthy adult women. To enhance antibody responses to all clinically relevant Alps, a second-generation vaccine has been developed (AlpN), also containing the N-terminal domain of Alp1 and the one shared by Alp2 and Alp3. In this study, the safety and immunogenicity of AlpN is assessed in a randomized, double-blind, placebo-controlled, and parallel-group phase I study, involving 60 healthy non-pregnant women. AlpN is well tolerated and elicits similarly robust and persistent antibody responses against all four Alp-N-terminal domains, resulting in enhanced opsonophagocytic killing of all Alp serotypes covered by the vaccine.

A group B Streptococcus alpha-like protein subunit vaccine induces functionally active antibodies in humans targeting homotypic and heterotypic strains.

Maternal vaccination is a promising strategy for preventing neonatal disease caused by group B Streptococcus. The safety and immunogenicity of the prototype vaccine GBS-NN, a fusion protein consisting of the N-terminal domains of the alpha-like proteins (Alp) αC and Rib, were recently evaluated favorably in healthy adult women in a phase 1 trial. Here we demonstrate robust immunoglobulin G (IgG) and immunoglobulin A (IgA) responses against αC and Rib, as well as against the heterotypic Alp family members Alp1-Alp3. IgA and heterotypic IgG responses are more variable between subjects and correlate with pre-existing immunity. Vaccine-induced IgG mediates opsonophagocytic killing and prevents bacterial invasion of epithelial cells. Like the vaccine-induced response, naturally acquired IgG against the vaccine domains is dominated by IgG1. Consistent with the high IgG1 cross-placental transfer rate, naturally acquired IgG against both domains reaches higher concentrations in neonatal than maternal blood, as assessed in a separate group of non-vaccinated pregnant women and their babies.

Safety and immunogenicity of a prototype recombinant alpha-like protein subunit vaccine (GBS-NN) against Group B Streptococcus in a randomised placebo-controlled double-blind phase 1 trial in healthy adult women.

BACKGROUND: Group B Streptococcus (GBS) is the leading cause of life-threatening infections in new-borns and may cause invasive disease, stillbirth and preterm delivery during pregnancy. While no licensed vaccine exists, maternal immunization might protect against neonatal disease and adverse pregnancy outcomes. We assessed the safety and immunogenicity of a prototype vaccine consisting of the fused N-terminal domains of the AlphaC and Rib surface proteins of GBS (GBS-NN). METHODS: GBS-NN was tested in a randomised, double-blind, placebo-controlled, parallel group, phase I study, in healthy non-pregnant women. A dose-escalation phase, with two doses, four weeks apart, of 10, 50 or 250 µg, administered with or without aluminium hydroxide, was initially assessed (n = 60). This was followed by a dose-confirmation study, where one dose of 100 µg adjuvanted GBS-NN was compared with two doses of either 50 or 100 µg adjuvanted GBS-NN, again administered with four weeks interval between the doses (n = 180). Safety and immunogenicity were monitored for one year. RESULTS: GBS-NN was well tolerated with some, mostly mild, injection site reactions observed. Adjuvant significantly increased antibody concentrations and the response was boosted by a second dose. The IgG GMCs remained strongly elevated during the whole one-year duration of the study. Maximal responses occurred after two 50 µg doses, resulting in IgG GMC of 16.9 µg/ml at the primary immunological endpoint, twelve weeks after the first dose. For this regimen, 100% and 89% of the subjects achieved antibody levels above the arbitrary thresholds of 1 and 4 µg/ml, respectively. The added beneficial effect of a second dose was most pronounced for subjects with pre-existing IgG levels below the median of the entire cohort. CONCLUSION: The prototype GBS-NN vaccine was found to be well tolerated and highly immunogenic with an optimal regimen of two doses of 50 µg in the presence of adjuvant. Further development of a maternal vaccine based on the N-terminal domains of the alpha-like protein family of GBS is warranted (NCT02459262).

Pathogenic autoreactive B cells are not negatively selected toward matrix protein collagen II.

We have addressed the importance of B cell tolerance to collagen type II, a matrix protein, which is a target in rheumatoid arthritis (RA) and its mouse models. We generated a germline-encoded anti-collagen type II (CII) IgH replacement anti-C1 B cell mouse strain (ACB) to investigate how B cell tolerance to CII, a matrix protein, is subverted and to further understand pathogenesis of RA. Phenotypic analysis revealed that CII-specific B cells were surprisingly neither deleted nor anergized. Instead, they were readily detected in all lymphoid organs. Spontaneously produced autoantibodies could bind directly to cartilage surface without detectable pathology. However, exaggerated arthritis was seen after injection of anti-CII Abs specific for other epitopes. In addition, Abs from CII-specific hybridomas generated from ACB mice induced arthritis. Interestingly, IgH/L chain sequence data in B cell hybridomas revealed a lack of somatic mutations in autoreactive B cells. The ACB model provides the first possibility, to our knowledge, to study B cell tolerance to a matrix protein, and the observations made in the study could not be predicted from previous models. B cell-reactive epitopes on CII are largely shared between human RA and rodent CII-induced arthritis; this study, therefore, has important implications for further understanding of pathological processes in autoimmune diseases like RA.

CD25brightCD4+ regulatory T cells are enriched in inflamed joints of patients with chronic rheumatic disease.

CD25+CD4+ regulatory T cells participate in the regulation of immune responses. We recently demonstrated the presence of CD25brightCD4+ regulatory T cells with a capacity to control T cell proliferation in the joints of patients with rheumatoid arthritis. Here, we investigate a possible accumulation of these regulatory T cells in the inflamed joint of different rheumatic diseases including rheumatoid arthritis. The studies are also extended to analyze whether cytokine production can be suppressed by the regulatory T cells. Synovial fluid and peripheral blood samples were obtained during relapse from 36 patients with spondyloarthropathies, 21 adults with juvenile idiopathic arthritis and 135 patients with rheumatoid arthritis, and the frequency of CD25brightCD4+ T cells was determined. Of 192 patients, 182 demonstrated a higher frequency of CD25brightCD4+ T cells in synovial fluid than in peripheral blood. In comparison with healthy subjects, the patients had significantly fewer CD25brightCD4+ T cells in peripheral blood. For functional studies, synovial fluid cells from eight patients were sorted by flow cytometry, and the suppressive capacity of the CD25brightCD4+ T cells was determined in in vitro cocultures. The CD25brightCD4+ T cells suppressed the production of both type 1 and 2 cytokines including interleukin-17, as well as proliferation, independently of diagnosis. Thus, irrespective of the inflammatory joint disease investigated, CD25brightCD4+ T cells were reduced in peripheral blood and enriched in the joint, suggesting an active recruitment of regulatory T cells to the affected joint. Their capacity to suppress both proliferation and cytokine secretion might contribute to a dampening of local inflammatory processes.

Isolation and functional characterization of regulatory CD25brightCD4+ T cells from the target organ of patients with rheumatoid arthritis.

In the homeostasis of the immune system regulatory cells play a major role. Removal of one group of regulatory cells, the CD25(+)CD4(+) T cells, leads to autoimmune manifestations in experimental animal models, and reintroduction of this population prevents disease. This study addresses the role of such regulatory T cells in humans with an autoimmune disease, where we demonstrate the presence of CD25(bright)CD4(+) T cells in the target organ of patients with active rheumatoid arthritis. The patients displayed an enrichment of CD25(bright)CD4(+) T cells in synovial fluid as compared to peripheral blood. These cells are functional regulatory cells, as they were able to suppress in vitro proliferation of autologous T cells, both from synovial and peripheral blood origin. Although the frequency of CD25(bright)CD4(+) T cells varied between patients, it was found to be constant over time in any one joint during each relapse. Numbers were also comparable in two inflamed knee joints of one and the same patient, emphasizing the symmetry of the disease. In summary, it is striking that in addition to all activated, potentially pathological T cells the synovial fluid from RA patients also contains CD25-expressing CD4(+) T cells with a regulatory capacity.