Generation of a universal CD4 memory T cell recall peptide effective in humans, mice and non-human primates.

CD4T cells play a key role in humoral immunity by providing help to B cells, enabling effective antibody class switching and affinity maturation. Some vaccines may generate a poor response due to a lack of effective MHC class II epitopes, resulting in ineffective helper T cell activation and recall and consequently poor humoral immunity. It may be beneficial to provide a CD4T cell helper peptide with a vaccine particularly in the case of a poorly immunogenic antigen. Such a T cell helper peptide must be promiscuous in its ability to bind a broad range of MHC class II alleles due to broad allelic variation in the human population. We designed a chimeric MHC class II peptide (TpD) with epitopes from tetanus toxoid and diphtheria toxoid, separated by an internal cathepsin cleavage site. TpD was capable of inducing a memory recall response in peripheral blood mononuclear cells from 20/20 human donors. T cells responding to TpD showed a central memory phenotype. Immunization of mice with a synthetic nicotine nanoparticle vaccine containing TpD showed that the peptide was required for robust antibody production and resulted in a long term CD4 memory T cell recall response. As a pre-clinical model two non-human primate species, rhesus macaques and cynomolgus monkeys, were immunized with a nicotine nanoparticle vaccine and evaluated for an anti-nicotine antibody response and TpD specific memory T cells. We found that 4/4 rhesus monkeys had both sustained antibody production and TpD memory T cells for the duration of the experiment (119 days). In addition 30/30 cynomolgus monkeys dosed with nicotine vaccine nanoparticles showed dose-dependent antibody generation and T cell recall response compared to saline injected controls. In summary we have developed a potent universal memory T cell helper peptide (TpD) that is active in vitro in human PBMCs and in vivo in mice and non-human primates.

Earliest innate immune responses require macrophage RelA during pneumococcal pneumonia.

NF-κB regulates cytokine expression to initiate and control the innate immune response to lung infections. The NF-κB protein RelA is critical for pulmonary host defense during Streptococcus pneumoniae pneumonia, but the cell-specific roles of this transcription factor remain to be determined. We hypothesized that RelA in alveolar macrophages contributes to cytokine expression and host defense during pneumococcal pneumonia. To test this hypothesis, we compared mice lacking RelA exclusively in myeloid cells (RelA(Δ/Δ)) with littermate controls (RelA(F/F)). Alveolar macrophages from RelA(Δ/Δ) mice expressed no full-length RelA, demonstrating effective targeting. Alveolar macrophages from RelA(Δ/Δ) mice exhibited reduced, albeit detectable, proinflammatory cytokine responses to S. pneumoniae, compared with alveolar macrophages from RelA(F/F) mice. Concentrations of these cytokines in lung homogenates were diminished early after infection, indicating a significant contribution of macrophage RelA to the initial expression of cytokines in the lungs. However, the cytokine content in infected lungs was equivalent by 15 hours. Neutrophil recruitment during S. pneumoniae pneumonia reflected a delayed onset in RelA(Δ/Δ) mice, followed by similar rates of accumulation. Bacterial clearance was eventually effective in both genotypes, but began later in RelA(Δ/Δ) mice. Thus, during pneumococcal pneumonia, only the earliest induction of the cytokines measured depended on transcription by RelA in myeloid cells, and this transcriptional activity contributed to effective immunity.