Jaganathan K S, Vyas Suresh P
Drug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Dr. Hari Singh Gour University, Sagar 470003, MP, India.
Vaccine. 2006 May 8;24(19):4201-11. doi: 10.1016/j.vaccine.2006.01.011. Epub 2006 Jan 18.
Surface-modified DL-lactide/glycolide copolymer (PLGA) microspheres with chitosan (CS) were developed for nasal immunization using recombinant Hepatitis B (HBsAg) surface protein for the induction of humoral, cellular and mucosal immunity. Modified PLGA microspheres were characterized in vitro for their size, shape, entrapment efficiency and zeta potential. The nasal clearance rate was evaluated by gamma scintigraphy in rabbits. The antigen integrity, in vitro release and its stability at 37 degrees C were also evaluated. The designed cationic microspheres possessed 27.2 mV zeta potential and an average size less than 10 microm with antigen loading efficiency of 80+/-5%. However, zeta potential of unmodified PLGA microspheres was measured to be negative (-8.7 mV). The modified PLGA microspheres showed the lowest nasal clearance rate when compared with unmodified PLGA microspheres and lactose powder. The antigen integrity was retained intact in encapsulated form as well as on release. The immune-stimulating activity was studied by measuring anti-HBsAg titre, secretory IgA level in serum, vaginal, nasal and salivary secretions (mucosal secretions) and cytokine level (interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)) in spleen homogenates following nasal administration of modified PLGA microspheres in Balb/c mice and compared with alum-HBsAg vaccine injected subcutaneously. The serum anti-HBsAg titre obtained after nasal administration of modified PLGA microspheres was comparable with titre recorded after alum-HBsAg was administered subcutaneously. Moreover, alum-HBsAg vaccine did not elicit sIgA in mucosal secretions as it was induced and measured in the case of nasal administration of modified PLGA microspheres. Similarly, there was no cellular response (cytokine level) in case of alum-HBsAg vaccine. Modified PLGA microspheres (cationic microspheres) thus produced humoral (both systemic and mucosal) and cellular immune responses upon nasal administration. These data demonstrate high potential of modified PLGA microspheres for their use as a carrier adjuvant for nasal subunit vaccines.
开发了用壳聚糖（CS）进行表面改性的聚乳酸-乙醇酸共聚物（PLGA）微球，用于鼻腔免疫，使用重组乙肝表面蛋白诱导体液免疫、细胞免疫和黏膜免疫。对改性PLGA微球的大小、形状、包封率和zeta电位进行了体外表征。通过γ闪烁显像法评估家兔的鼻腔清除率。还评估了抗原完整性、体外释放及其在37℃下的稳定性。设计的阳离子微球zeta电位为27.2 mV，平均粒径小于10微米，抗原负载效率为80±5%。然而，未改性PLGA微球的zeta电位测得为负值（-8.7 mV）。与未改性PLGA微球和乳糖粉相比，改性PLGA微球的鼻腔清除率最低。抗原完整性在包封形式以及释放时均保持完整。通过在Balb/c小鼠鼻腔给药改性PLGA微球后，测量抗乙肝表面抗原滴度、血清、阴道、鼻腔和唾液分泌物（黏膜分泌物）中的分泌型IgA水平以及脾匀浆中的细胞因子水平（白细胞介素-2（IL-2）和干扰素-γ（IFN-γ））来研究免疫刺激活性，并与皮下注射明矾-乙肝表面抗原疫苗进行比较。鼻腔给药改性PLGA微球后获得的血清抗乙肝表面抗原滴度与皮下注射明矾-乙肝表面抗原后记录的滴度相当。此外，明矾-乙肝表面抗原疫苗在黏膜分泌物中未诱导出分泌型IgA，而鼻腔给药改性PLGA微球时则可诱导并检测到。同样，明矾-乙肝表面抗原疫苗未引发细胞反应（细胞因子水平）。因此，改性PLGA微球（阳离子微球）鼻腔给药后可产生体液免疫（全身和黏膜）和细胞免疫反应。这些数据表明改性PLGA微球作为鼻腔亚单位疫苗的载体佐剂具有很高的潜力。
