College of Pharmacy, Ajou University, Suwon, 16499, Republic of Korea.
Research Institute of Pharmaceutical Science and Technology, Ajou University, Suwon, 16499, Republic of Korea.
Int J Nanomedicine. 2022 Dec 9;17:6221-6231. doi: 10.2147/IJN.S379950. eCollection 2022.
A recombinant protein cannot induce sufficient immune response by itself. Various substances, including cytokine and mineral, have been used as adjuvants to enhance the immunogenicity and efficacy of vaccines; however, most of them induce excessive immune responses or exhibit cytotoxicity. In this study, a self-emulsifying drug delivery system (SEDDS), an isotropic mixture of oil, surfactant, and solvent, was designed for oil-in-water emulsions as a non-toxic adjuvant to increase immune response to antigens.
Squalene-based oil-in-water emulsions were prepared by SEDDS to assess its value as an adjuvant. Fifteen emulsions (F1-F15) were prepared by stirring two types of surfactants (Span 85 and Kolliphor RH40), and squalene and carboxymethyl cellulose (CMC) were added at different ratios. The physical properties and viscosity of the 15 emulsions were evaluated by measuring droplet size, zeta potential, and polydispersity index. The toxic effect of emulsions was assessed by acute toxicity test in mice. Mice were immunized twice with 1:1 mixtures of antigen and adjuvant (15 emulsions, phosphate-buffered saline, and commercial alum-based adjuvant). Antigen-specific antibody titers from immunized mice serum were measured by an indirect enzyme-linked immunosorbent assay.
All emulsions exhibited droplet sizes ranging from 322 to 812 nm and maintained zeta potential values between -30 mV to -10 mV for 4 weeks, indicating good physical stability as a vaccine adjuvant. Additionally, all emulsions were non-toxic, and they induced humoral immunity at a similar level compared to commercial alum-based adjuvant in the first immunization. However, 12% squalene-based oil-in-water emulsion containing 0.5% of ultra-high viscosity CMC (F15) showed significantly higher immune response than a commercial adjuvant in the second immunization.
Squalene-based oil-in-water emulsions could be conveniently prepared using SEDDS technique and are non-toxic and stable at room temperature storage. Moreover, squalene-based oil-in-water emulsions show enhanced immune induction with antigen; hence, they can possibly be used as effective adjuvants.
重组蛋白本身不能诱导足够的免疫反应。为了增强疫苗的免疫原性和疗效，已经使用了包括细胞因子和矿物质在内的各种物质作为佐剂；然而，它们大多数会引起过度的免疫反应或表现出细胞毒性。在本研究中，设计了一种自乳化药物递送系统（SEDDS），一种油、表面活性剂和溶剂的各向同性混合物，作为水包油乳液的无毒佐剂，以增加抗原的免疫反应。
通过 SEDDS 制备角鲨烯基水包油乳液，以评估其作为佐剂的价值。制备了 15 种乳液（F1-F15），通过搅拌两种类型的表面活性剂（Span 85 和 Kolliphor RH40），并以不同的比例添加角鲨烯和羧甲基纤维素（CMC）。通过测量粒径、Zeta 电位和多分散指数来评估 15 种乳液的物理性质和粘度。通过急性毒性试验评估乳液的毒性作用。用抗原和佐剂（15 种乳液、磷酸盐缓冲液和商业铝基佐剂）的 1:1 混合物对小鼠进行两次免疫。通过间接酶联免疫吸附试验测量免疫小鼠血清中的抗原特异性抗体滴度。
所有乳液均表现出 322nm 至 812nm 的粒径，并在 4 周内保持-30mV 至-10mV 的 Zeta 电位值，表明作为疫苗佐剂具有良好的物理稳定性。此外，所有乳液均无毒，并且与商业铝基佐剂相比，在第一次免疫时均能诱导相似水平的体液免疫。然而，含有 0.5%超高粘度 CMC 的 12%角鲨烯基水包油乳液（F15）在第二次免疫时表现出比商业佐剂更高的免疫反应。
角鲨烯基水包油乳液可通过 SEDDS 技术方便地制备，在室温下储存时无毒且稳定。此外，角鲨烯基水包油乳液与抗原一起显示出增强的免疫诱导作用；因此，它们可能可用作有效的佐剂。
