School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
Front Immunol. 2022 Jun 15;13:910192. doi: 10.3389/fimmu.2022.910192. eCollection 2022.
Viral respiratory infections cause substantial health and economic burden. There is a pressing demand for efficacious vaccination strategies and, therefore, a need for a better understanding of the mechanisms of action of novel potential adjuvants. Here we investigated the effect of a synthetic RIG-I agonist, the dsRNA hairpin 3p10LA9, on the activation of pulmonary myeloid cells. Analysis of early innate immune responses revealed that a single intranasal 3p10LA9 dose induces a transient pulmonary interferon-stimulated gene (ISG) and pro-inflammatory cytokine/chemokine response, which leads to the maturation of three distinct dendritic cell subpopulations in the lungs. While lung resident dendritic cell decrease shortly after 3p10LA9 delivery, their numbers increase in the draining mediastinal lymph node, where they have migrated, maintaining their activated phenotype. At the same time, dsRNA hairpin-induced chemokines attract transiently infiltrating monocytes into the lungs, which causes a short temporary pulmonary inflammation. However, these monocytes are dispensable in controlling influenza infection since in CCR2 deficient mice, lacking these infiltrating cells, the virus load was similar to the wild type mice when infected with the influenza virus at a sublethal dose. In summary, our data suggest that intranasal delivery of dsRNA hairpins, used as a RIG-I targeting adjuvant, represents an attractive strategy to boost type I inteferon-mediated lung dendritic cell maturation, which supports viral reduction in the lungs during infection.
病毒呼吸道感染会造成严重的健康和经济负担。人们迫切需要有效的疫苗接种策略,因此需要更好地了解新型潜在佐剂的作用机制。在这里,我们研究了一种合成 RIG-I 激动剂,双链 RNA 发夹 3p10LA9,对肺部髓样细胞激活的影响。早期先天免疫反应的分析表明,单次鼻腔内 3p10LA9 剂量会诱导短暂的肺部干扰素刺激基因(ISG)和促炎细胞因子/趋化因子反应,从而导致肺部三种不同树突状细胞亚群的成熟。虽然 3p10LA9 给药后肺驻留树突状细胞数量短暂减少,但它们在引流的纵隔淋巴结中数量增加,在那里它们已经迁移并保持激活表型。与此同时,dsRNA 发夹诱导的趋化因子会短暂地将浸润的单核细胞吸引到肺部,导致短暂的肺部炎症。然而,这些单核细胞在控制流感感染中是可有可无的,因为在 CCR2 缺陷小鼠中,缺乏这些浸润细胞,当用亚致死剂量的流感病毒感染时,病毒载量与野生型小鼠相似。总之,我们的数据表明,作为 RIG-I 靶向佐剂的 dsRNA 发夹的鼻腔内给药代表了一种有吸引力的策略,可以促进 I 型干扰素介导的肺部树突状细胞成熟,从而在感染期间支持肺部病毒减少。