Biodegradable PLGA85/15 nanoparticles as a delivery vehicle for Chlamydia trachomatis recombinant MOMP-187 peptide

摘要

Development of a Chlamydia trachomatis vaccine has been a formidable task partly because of an ineffective delivery system. Our laboratory has generated a recombinant peptide of C.trachomatis major outer membrane protein (MOMP) (rMOMP-187) and demonstrated that it induced at 20μgml 1 maximal interleukin (IL)-6 and IL-12p40 Th1 cytokines in mouse J774 macrophages. In a continuous pursuit of a C.trachomatis effective vaccine-delivery system, we encapsulated rMOMP-187 in poly(d,l-lactic-co-glycolic acid) (PLGA, 85:15 PLA/PGA ratio) to serve as a nanovaccine candidate. Physiochemical characterizations were assessed by Fourier transform-infrared spectroscopy, atomic force microscopy, Zetasizer, Zeta potential, transmission electron microcopy and differential scanning calorimetry. The encapsulated rMOMP-187 was small (200nm) with an apparently smooth uniform oval structure, thermally stable (54°C), negatively charged (27.00mV) and exhibited minimal toxicity at concentrations <250μg ml ~1 to eukaryotic cells (>95% viable cells) over a 24-72h period. We achieved a high encapsulation efficiency of rMOMP-187 (98%) in PLGA, a loading peptide capacity of 2.7% and a slow release of the encapsulated peptide. Stimulation of J774 macrophages with a concentration as low as 1μg ml ~1 of encapsulated rMOMP-187 evoked high production levels of the Th1 cytokines IL-6 (874pgml ~1) and IL-12p40 (674pgml ~1) as well as nitric oxide (8μM) at 24h post-stimulation, and in a dose-response and time-kinetics manner. Our data indicate the successful encapsulation and characterization of rMOMP-187 in PLGA and, more importantly, that PLGA enhanced the capacity of the peptide to induce Th1 cytokines and NO invitro. These findings make this nanovaccine an attractive candidate in pursuit of an efficacious vaccine against C.trachomatis.