Chemokine programming dendritic cell antigen response: part I - select chemokine programming of antigen uptake even after maturation.

Here, we report on the successful programming of dendritic cells (DCs) using selectively applied mixtures of chemokines as a novel protocol for engineering vaccine efficiency. Antigen internalization by DCs is a pivotal step in antigen uptake/presentation for bridging innate and adaptive immunity and in exogenous gene delivery used in vaccine strategies. Contrary to most approaches to improve vaccine efficiency, active enhancement of antigen internalization by DCs as a vaccine strategy has been less studied because DCs naturally down-regulate antigen internalization upon maturation. Whereas chemokines are mainly known as signal proteins that induce leucocyte chemotaxis, very little research has been carried out to identify any additional effects of chemokines on DCs following maturation. Here, immature DCs are pre-treated with select chemokines before intentional maturation using lipopolysaccharide (LPS). When pre-treated with a mixture of CCL3 and CCL19 in a 7 : 3 ratio, then matured with LPS, chemokine pre-treated DCs exhibited 36% higher antigen uptake capacity than immature DCs and 27% higher antigen-processing capacity than immature DCs treated only with LPS. Further, CCL3 : CCL19 (7 : 3) pre-treatment of DCs modulated MHC molecule expression and secretion of various cytokines of DCs. Collectively, DC programming was feasible using a specific chemokine combination and these results provide a novel strategy for enhancing DC-based vaccine efficiency. In Part II, we report on the phenotype changes and antigen presentation capacity of chemokine pre-treated murine bone marrow-derived DCs examined in long-term co-culture with antigen-specific CD4(+) T cells.

Improvement of a potential anthrax therapeutic by computational protein design.

Past anthrax attacks in the United States have highlighted the need for improved measures against bioweapons. The virulence of anthrax stems from the shielding properties of the Bacillus anthracis poly-γ-d-glutamic acid capsule. In the presence of excess CapD, a B. anthracis γ-glutamyl transpeptidase, the protective capsule is degraded, and the immune system can successfully combat infection. Although CapD shows promise as a next generation protein therapeutic against anthrax, improvements in production, stability, and therapeutic formulation are needed. In this study, we addressed several of these problems through computational protein engineering techniques. We show that circular permutation of CapD improved production properties and dramatically increased kinetic thermostability. At 45 °C, CapD was completely inactive after 5 min, but circularly permuted CapD remained almost entirely active after 30 min. In addition, we identify an amino acid substitution that dramatically decreased transpeptidation activity but not hydrolysis. Subsequently, we show that this mutant had a diminished capsule degradation activity, suggesting that CapD catalyzes capsule degradation through a transpeptidation reaction with endogenous amino acids and peptides in serum rather than hydrolysis.