Delivering therapeutic nucleic acids to targeted cells and organs has been a challenge for decades. A novel technology to deliver oligonucleotide therapeutics to immune cells is here described. In this approach, a macromolecular complex of oligonucleotides and the β-1,3-glucan schizophyllan (SPG) is selectively delivered to cells expressing a lectin receptor, Dectin-1, via SPG–Dectin-1 interaction. Detailed investigation of Dectin-1-expressing cells revealed that Dectin-1 is expressed in all subsets of monocytes as well as dendritic cell (DC) populations, including conventional DCs (cDCs) and plasmacytoid DCs (pDCs), in humans. The expression patterns in mice and humans are comparable, except for the expression in pDCs. The results indicate that Dectin-1 is expressed on cells capable of professional antigen presentation, except for B cells. We chose CD40 as a target gene for small interfering RNA (siRNA) as CD40 expression in antigen-presenting cells (APCs), particularly in DCs, plays critical roles in regulating immune responses. Dose-dependent cellular uptake of siCD40–SPG complexes was confirmed in cells expressing Dectin-1. Gene silencing activity was confirmed in vitro by the reduction of CD40 mRNA and by the site-specific cleavage of CD40 mRNA as determined by the 5’ RNA ligase-mediated rapid amplification of cDNA ends (5’RLM-RACE) technique. In vivo activity of siCD40–SPG complexes was demonstrated as the reduced CD40 protein expression in monocytes and DCs in mice. Furthermore, the in vivo activity of siCD40–SPG targeting human CD40 was confirmed in cynomolgus monkeys by the 5’RLM-RACE technique. In conclusion, we have demonstrated the receptor-ligand binding-mediated delivery of siRNA targeting immune-regulating monocytes and DCs via the interaction of SPG and its receptor, Dectin-1. As monocytes and DCs play central roles in inducing and controlling immune responses, Dectin-1-targeted delivery of nucleic acids should provide a useful tool for developing drugs to treat a wide range of diseases, including autoimmune diseases, allergy, and cancer, as well as transplantation.

数十年来，向靶细胞和器官递送治疗性核酸一直是一项挑战。这里描述了一种向免疫细胞递送寡核苷酸疗法的新技术。在这种方法中，寡核苷酸和 β-1,3-葡聚糖裂叶多糖 (SPG) 的大分子复合物通过 SPG-Dectin-1 相互作用被选择性地传递到表达凝集素受体 Dectin-1 的细胞中。对表达 Dectin-1 的细胞的详细调查表明，Dectin-1 在人类的所有单核细胞亚群以及树突细胞 (DC) 群体中表达，包括常规 DC (cDC) 和浆细胞样 DC (pDC)。除了在 pDC 中的表达外，小鼠和人类的表达模式是可比的。结果表明，Dectin-1 在能够专职抗原呈递的细胞上表达，B 细胞除外。我们选择 CD40 作为小干扰 RNA (siRNA) 的靶基因，因为 CD40 在抗原呈递细胞 (APC) 中的表达，特别是在 DC 中，在调节免疫反应中起关键作用。在表达 Dectin-1 的细胞中证实了 siCD40-SPG 复合物的剂量依赖性细胞摄取。基因沉默活性在体外通过 CD40 mRNA 的减少和 CD40 mRNA 的位点特异性切割得到证实，由 5' RNA 连接酶介导的 cDNA 末端快速扩增 (5'RLM-RACE) 技术确定。siCD40-SPG 复合物的体内活性被证明为小鼠单核细胞和 DC 中 CD40 蛋白表达的降低。此外，通过 5'RLM-RACE 技术在食蟹猴中证实了 siCD40-SPG 靶向人 CD40 的体内活性。综上所述，我们已经证明了通过 SPG 与其受体 Dectin-1 的相互作用靶向免疫调节单核细胞和 DC 的 siRNA 的受体-配体结合介导的递送。由于单核细胞和 DC 在诱导和控制免疫反应中发挥核心作用，Dectin-1 靶向核酸递送应为开发治疗多种疾病的药物提供有用的工具，包括自身免疫性疾病、过敏症和癌症，以及作为移植。