MicroRNAs (miRNAs) are post-transcriptional gene expression regulators with potential therapeutic applications. miR-146a is a negative regulator of inflammatory processes in both tissue-resident and specialized immune cells and may therefore have therapeutic effect in inflammatory skin diseases. PepFect (PF) and NickFect (NF) type of cell-penetrating peptides (CPPs) have previously been shown to deliver miRNA mimics and/or siRNAs into cell cultures and in vivo. Here, we first demonstrate that selected PF- and NF-type of CPPs support delivery of fluorescent labelled miRNA mimics into keratinocytes (KCs) and dendritic cells (DCs). Second, we show that both PF- and NF-miR-146a nanocomplexes were equally effective in KCs, while NFs were more efficient in DCs as assessed by downregulation of miR-146a-influenced genes. None of miRNA nanocomplexes with the tested CPPs influenced the viability of KCs and DCs nor caused activation of DCs according to CD86 and CD83 markers. Transmission electron microscopy analysis with Nanogold-labelled miR-146a mimics and assessment of endocytic trafficking pathways revealed endocytosis as an active route of delivery in both KCs and DCs for all tested CPPs. However, consistent with the higher efficiency, NF-delivered miR-146a was detected more often outside endosomes in DCs. Finally, pre-injection of NF71:miR-146a nanocomplexes was confirmed to suppress inflammatory responses in a mouse model of irritant contact dermatitis as shown by reduced ear swelling response and downregulation of pro-inflammatory cytokines, including IL-6, IL-1β, IL-33 and TNF-α. In conclusion, NF71 efficiently delivers miRNA mimics into KCs as well as DCs, and therefore may have advantage in therapeutic delivery of miRNAs in case of inflammatory skin diseases.

MicroRNA（miRNA）是转录后基因表达调节剂，具有潜在的治疗应用。miR-146a在组织驻留和特异性免疫细胞中均是炎症过程的负调节剂，因此可能在炎症性皮肤病中具有治疗作用。PepFect（PF）和NickFect（NF）类型的细胞穿透肽（CPP）先前已被证明可以将miRNA模拟物和/或siRNA传递到细胞培养物中和体内。在这里，我们首先证明所选的PF型和NF型CPP支持将荧光标记的miRNA模拟物递送至角质形成细胞（KC）和树突状细胞（DC）。其次，我们证明PF-和NF-miR-146a纳米复合物在KCs中同样有效，而NFs在DCs中更有效，这是通过下调miR-146a影响的基因来评估的。根据CD86和CD83标记，没有一种带有被测CPP的miRNA纳米复合物不会影响KC和DC的活力，也不会引起DC的活化。用纳米金标记的miR-146a模拟物进行的透射电子显微镜分析和内吞运输途径的评估显示，内吞作用是所有测试CPP在KC和DC中均作为主动递送途径。但是，与更高的效率相一致，在DC中的内体外部更经常检测到NF传递的miR-146a。最后，证实了NF71：miR-146a纳米复合物的预注射可抑制刺激性接触性皮炎小鼠模型的炎症反应，如耳肿胀反应减轻和促炎性细胞因子（包括IL-6，IL-1β， IL-33和TNF-α。总之，NF71将miRNA模拟物有效地递送至KC和DC中，因此在炎症性皮肤病的情况下，在miRNA的治疗性递送中可能具有优势。