PLGA微球粒径对HPV L1五聚体候选疫苗免疫效果的调控

以聚乳酸-羟基乙酸共聚物(PLGA)为疫苗递送和佐剂系统，采用快速膜乳化技术制备了粒径0.43和1.38 mm的均一PLGA微球，以其包埋HPV L1五聚体抗原，考察微球粒径对体内免疫应答强度和水平的影响. 结果表明，1.38 mm粒径载抗原PLGA微球组产生的IgG滴度(87771±24983.0)和中和抗体滴度(30720±15863.7)显著高于0.43 mm粒径组的IgG滴度(38400±14021.7) (P<0.05)和中和抗体滴度(2480±3892.6) (P<0.01)，且1.38 mm载抗原PLGA微球能更显著提高Th2型细胞因子IL-6(0.43 mm微球的4.7倍)和IL-4(0.43 mm微球的1.5倍)的分泌水平；而0.43 mm载抗原PLGA微球能显著提升Th1型细胞因子IFN-γ(1.38 mm微球的2.1倍)的分泌水平，表明对于HPV疫苗佐剂与递送系统，小粒径微球有利于细胞免疫的提升，可用于治疗性疫苗的开发；而大粒径微球则有利于诱导高效体液免疫，可用于预防性疫苗的开发.

Effect of PLGA Microsphere Size on Regulation of Immune Response for HPV L1 Capsomere-based Candidate Vaccine

Two-sized poly(lactic-co-glycolic acid) (PLGA) microspheres prepared by membrane emulsification technique were used as vaccine delivery and adjuvant system. The effect of particle size on enhancing HPV L1 specific immune responses was investigated. The results showed that HPV L1 pentamers encapsulated in large-sized PLGA (1.38 mm) microspheres could elicit significantly higher level of IgG binding antibodies (87771±24983.0) and neutralizing antibodies (30720±15863.7) than the counterparts with 0.43 mm (38400±14021.7) and (2480±3892.6) (P<0.05 and P<0.01). The similar trend was also found in cytokine secretion levels, and higher levels of IL-6 (4.7 times of the cytokines for small-sized microspheres) and IL-4 (1.5 times of the cytokines for small-sized microspheres) were observed in mice immunized with large-sized PLGA microspheres (1.38 mm) encapsulating HPV L1 pentamers. While small-sized PLGA microspheres (0.43 mm) encapsulating HPV L1 pentamers elicited significantly higher IFN-γ secretion levels (2.1 times of the cytokine for the large-sized microspheres) than large-sized PLGA microspheres (1.38 mm). Small-sized PLGA microspheres can enhance antigen specific cellular immune responses, which is suitable for therapeutic vaccine, while large-sized PLGA microspheres can elicit higher level of humoral immune responses, which is favorable for prophylactic HPV vaccine.