Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India.
J R Soc Interface. 2011 Dec 7;8(65):1748-59. doi: 10.1098/rsif.2011.0114. Epub 2011 May 4.
To evaluate the thermo-responsive poly(N-isopropylacrylamide) (PNiPAAm) polymer as an adjuvant, we synthesized PNiPAAm through free radical polymerization and characterized it both in vitro and in vivo. The polymer when mixed with collagen type II (CII) induced antigen-specific autoimmunity and arthritis. Mice immunized with PNiPAAm-CII developed significant levels of CII-specific IgG response comprising major IgG subclasses. Antigen-specific cellular recall response was also enhanced in these mice, while negligible level of IFN-γ was detected in splenocyte cultures, in vitro. PNiPAAm-CII-immunized arthritic mouse paws showed massive infiltration of immune cells and extensive damage to cartilage and bone. As determined by immunostaining, most of the CII protein retained its native configuration after injecting it with PNiPAAm in naive mice. Physical adsorption of CII and the high-molecular-weight form of moderately hydrophobic PNiPAAm induced a significant anti-CII antibody response. Similar to CII, mice immunized with PNiPAAm and ovalbumin (PNiPAAm-Ova) induced significant anti-ovalbumin antibody response. Comparable levels of serum IFN-γ, IL-1β and IL-17 were observed in ovalbumin-immunized mice with complete Freund, incomplete Freund (CFA and IFA) or PNiPAAm adjuvants. However, serum IL-4 levels were significantly higher in PNiPAAm-Ova and CFA-Ova groups compared with the IFA-Ova group. Thus, we show for the first time, biocompatible and biodegradable thermo-responsive PNiPAAm can be used as an adjuvant in several immunological applications as well as in better understanding of the autoimmune responses against self-proteins.
为了评估温敏性聚（N-异丙基丙烯酰胺）（PNiPAAm）聚合物作为佐剂的作用，我们通过自由基聚合合成了 PNiPAAm，并对其进行了体外和体内特性研究。该聚合物与 II 型胶原（CII）混合后可诱导抗原特异性自身免疫和关节炎。用 PNiPAAm-CII 免疫的小鼠产生了高水平的 CII 特异性 IgG 反应，包括主要 IgG 亚类。这些小鼠的抗原特异性细胞回忆反应也得到了增强，而在体外脾细胞培养中检测到的 IFN-γ水平可忽略不计。PNiPAAm-CII 免疫的关节炎小鼠爪子显示大量免疫细胞浸润，软骨和骨广泛受损。通过免疫染色确定，在未用 PNiPAAm 预处理的小鼠中注射 PNiPAAm-CII 后，大部分 CII 蛋白保留其天然构象。CII 的物理吸附和中等疏水性 PNiPAAm 的高分子量形式诱导了显著的抗 CII 抗体反应。与 CII 类似，用 PNiPAAm 和卵清蛋白（PNiPAAm-Ova）免疫的小鼠也诱导了显著的抗卵清蛋白抗体反应。在完全弗氏佐剂（CFA）、不完全弗氏佐剂（IFA）或 PNiPAAm 佐剂免疫的卵清蛋白小鼠中，观察到类似水平的血清 IFN-γ、IL-1β 和 IL-17。然而，与 IFA-Ova 组相比，PNiPAAm-Ova 和 CFA-Ova 组的血清 IL-4 水平显著升高。因此，我们首次证明，生物相容性和可生物降解的温敏性 PNiPAAm 可用于多种免疫应用，以及更好地理解自身蛋白的自身免疫反应。
