Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral St, G4 0RE Glasgow, UK.
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral St, G4 0RE Glasgow, UK; Department of Infectious Disease Immunology, Center for Vaccine Research, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
J Control Release. 2020 Jul 10;323:125-137. doi: 10.1016/j.jconrel.2020.04.001. Epub 2020 Apr 2.
Although the well-known Toll like receptor 9 (TLR9) agonist CpGODN has shown promising results as vaccine adjuvant in preclinical and clinical studies, its in vivo stability and potential systemic toxicity remain a concern. In an effort to circumvent these issues, different strategies have been employed to increase its stability, localise action and reduce dosage. These include conjugation of CpGODN with proteins or encapsulation/adsorption of CpGODN into/onto liposomes, and have resulted in enhanced immunopotency compared to co-administration of free CpGODN and antigen. Here, we designed a novel delivery system of CpGODN based on its conjugation to serve as anchor for liposomes. Thiol-maleimide chemistry was utilised to covalently ligate the Group B Streptococcus (GBS) GBS67 protein antigen with the CpGODN TLR9 agonist. This treatment did not alter protein's ability to be recognised by specific antibodies or the CpGODN to function as a TLR9 agonist. Due to its negative charge, the protein conjugate readily electrostatically bound cationic liposomes composed of 1, 2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol and dimethyldioctadecylammonium bromide (DDA). The novel cationic liposomes-protein conjugate complex (GBS67-CpGODN+L) shared similar vesicle characteristics (size and charge) compared to free liposomes but exhibited different structure and morphology. Following intramuscular immunisation, GBS67-CpGODN+L formed a vaccine depot at the injection site and induced a remarkable increase of functional immune responses against GBS compared to the simple co-administration of GBS67, CpGODN and liposomes. This work demonstrates that the conjugation of CpGODN to GBS67 in conjunction with adsorption on cationic liposomes, can promote co-delivery leading to the induction of a multifaceted immune response at low antigen and CpGODN doses. Our findings highlight the potential for harnessing the immunostimulatory properties of different adjuvants to develop more effective nanostructure-based vaccine platforms.
虽然众所周知的 Toll 样受体 9（TLR9）激动剂 CpGODN 在临床前和临床研究中作为疫苗佐剂显示出了良好的效果，但它在体内的稳定性和潜在的全身毒性仍然是一个关注点。为了解决这些问题，人们采用了不同的策略来提高其稳定性、定位作用和降低剂量。这些策略包括将 CpGODN 与蛋白质缀合，或将 CpGODN 包封/吸附到脂质体中，与游离 CpGODN 和抗原联合给药相比，这些策略导致了免疫原性的增强。在这里，我们设计了一种基于 CpGODN 缀合的新型 CpGODN 传递系统，作为脂质体的锚定点。巯基-马来酰亚胺化学被用于将 B 群链球菌（GBS）GBS67 蛋白抗原与 TLR9 激动剂 CpGODN 共价连接。这种处理方法并没有改变该蛋白被特定抗体识别的能力，也没有改变 CpGODN 作为 TLR9 激动剂的功能。由于其带负电荷，该蛋白缀合物容易与由 1,2-二硬脂酰-sn-甘油-3-磷酸胆碱（DSPC）、胆固醇和二甲基十八烷基溴化铵（DDA）组成的阳离子脂质体静电结合。与游离脂质体相比，新型阳离子脂质体-蛋白缀合物复合物（GBS67-CpGODN+L）具有相似的囊泡特征（大小和电荷），但表现出不同的结构和形态。肌肉内免疫接种后，GBS67-CpGODN+L 在注射部位形成疫苗储存库，与简单的 GBS67、CpGODN 和脂质体联合给药相比，显著增加了针对 GBS 的功能性免疫应答。这项工作表明，CpGODN 与 GBS67 的缀合结合吸附在阳离子脂质体上，可以促进共递药，从而在低抗原和 CpGODN 剂量下诱导多方面的免疫反应。我们的发现强调了利用不同佐剂的免疫刺激特性来开发更有效的基于纳米结构的疫苗平台的潜力。
