Potential of Translationally Controlled Tumor Protein-Derived Protein Transduction Domains as Antigen Carriers for Nasal Vaccine Delivery.

Nasal vaccination offers a promising alternative to intramuscular (i.m.) vaccination because it can induce both mucosal and systemic immunity. However, its major drawback is poor absorption of large antigens in the nasal epithelium. Protein transduction domains (PTDs), also called cell-penetrating peptides, have been proposed as vehicles for nasal delivery of therapeutic peptides and proteins. Here, we evaluated the potential of a mutant PTD derived from translationally controlled tumor protein (designated TCTP-PTD 13) as an antigen carrier for nasal vaccines. We first compared the l- and d-forms of TCTP-PTD 13 isomers (l- or d-TCTP-PTD 13) as antigen carriers. Studies in mice demonstrated that nasally administered mixtures of the model antigen ovalbumin (OVA) and d-TCTP-PTD 13 induced higher plasma IgG titers and secretory IgA levels in nasal washes than nasally administered OVA alone, OVA/l-TCTP-PTD 13, or i.m.-injected OVA. Plasma IgG subclass responses (IgG1 and IgG2a) of mice nasally administered OVA/d-TCTP-PTD 13 showed that the predominant IgG subclass was IgG1, indicating a Th2-biased immune response. We also used synthetic CpG oligonucleotides (CpG) as a Th1 immune response-inducing adjuvant. Nasally administered CpG plus OVA/d-TCTP-PTD 13 was superior in eliciting systemic and mucosal immune responses compared to those induced by nasally administered OVA/d-TCTP-PTD 13. Furthermore, the OVA/CpG/d-TCTP-PTD 13 combination skewed IgG1 and IgG2a profiles of humoral immune responses toward a Th1 profile. These findings suggest that TCTP-derived PTD is a suitable vehicle to efficiently carry antigens and to induce more powerful antigen-specific immune responses and a more balanced Th1/Th2 response when combined with a DNA adjuvant.