Alkie Tamiru N, Taha-Abdelaziz Khaled, Barjesteh Neda, Bavananthasivam Jegarubee, Hodgins Douglas C, Sharif Shayan
Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
Pathology Department, Beni-Suef University, Al Shamlah, Beni-Suef, Egypt.
PLoS One. 2017 Jan 3;12(1):e0169154. doi: 10.1371/journal.pone.0169154. eCollection 2017.
Natural or synthetic Toll-like receptor (TLR) ligands trigger innate responses by interacting with distinct TLRs. TLR ligands can thus serve as vaccine adjuvants or stand-alone antimicrobial agents. One of the limitations of TLR ligands for clinical application is their short half-life and rapid clearance from the body. In the current study, encapsulation of selected TLR ligands in biodegradable poly(D,L-lactide-co-glycolide) polymer nanoparticles (PLGA NPs) was examined in vitro and in vivo as a means to prolong innate responses. MQ-NCSU cells (a chicken macrophage cell line) were treated with encapsulated or soluble forms of TLR ligands and the resulting innate responses were evaluated. In most cases, encapsulated forms of TLR ligands (CpG ODN 2007, lipopolysaccharide and Pam3CSK4) induced comparable or higher levels of nitric oxide and cytokine gene expression in macrophages, compared to the soluble forms. Encapsulated CpG ODN, in particular the higher dose, induced significantly higher expression of interferon (IFN)-γ and IFN-β until at least 18 hr post-treatment. Cytokine expression by splenocytes was also examined in chickens receiving encapsulated or soluble forms of lipopolysaccharide (a potent inflammatory cytokine inducer in chickens) by intramuscular injection. Encapsulated LPS induced more sustained innate responses characterized by higher expression of IFN-γ and IL-1β until up to 96 hr. The ability of TLR ligands encapsulated in polymeric nanoparticles to maintain prolonged innate responses indicates that this controlled-release system can extend the use of TLR ligands as vaccine adjuvants or as stand-alone prophylactic agents against pathogens.
天然或合成的Toll样受体（TLR）配体通过与不同的TLR相互作用来触发先天性免疫反应。因此，TLR配体可作为疫苗佐剂或单独的抗菌剂。TLR配体在临床应用中的局限性之一是其半衰期短且能迅速从体内清除。在本研究中，我们在体外和体内检测了将选定的TLR配体封装在可生物降解的聚（D，L-丙交酯-共-乙交酯）聚合物纳米颗粒（PLGA NPs）中作为延长先天性免疫反应的一种方法。用封装形式或可溶性形式的TLR配体处理MQ-NCSU细胞（一种鸡巨噬细胞系），并评估由此产生的先天性免疫反应。在大多数情况下，与可溶性形式相比，封装形式的TLR配体（CpG ODN 2007、脂多糖和Pam3CSK4）在巨噬细胞中诱导出相当或更高水平的一氧化氮和细胞因子基因表达。特别是封装的CpG ODN，较高剂量时，在处理后至少18小时内诱导干扰素（IFN）-γ和IFN-β的表达显著更高。通过肌肉注射接受封装或可溶性形式脂多糖（鸡体内一种强效炎症细胞因子诱导剂）的鸡的脾细胞的细胞因子表达也进行了检测。封装的LPS诱导更持久的先天性免疫反应，其特征是IFN-γ和IL-1β的表达更高，持续长达96小时。封装在聚合物纳米颗粒中的TLR配体维持延长的先天性免疫反应的能力表明，这种控释系统可以扩大TLR配体作为疫苗佐剂或作为针对病原体的单独预防剂的用途。
