Stroke is a leading cause of death and disability. Recovery depends on a delicate balance between inflammatory responses and immune suppression, tipping the scale between brain protection and susceptibility to infection. Peripheral cholinergic blockade of immune reactions fine-tunes this immune response, but its molecular regulators are unknown. Here, we report a regulatory shift in small RNA types in patient blood sequenced two days after ischemic stroke, comprising massive decreases of microRNA levels and concomitant increases of transfer RNA fragments (tRFs) targeting cholinergic transcripts. Electrophoresis-based size-selection followed by RT-qPCR validated the top 6 upregulated tRFs in a separate cohort of stroke patients, and independent datasets of small and long RNA sequencing pinpointed immune cell subsets pivotal to these responses, implicating CD14+ monocytes in the cholinergic inflammatory reflex. In-depth small RNA targeting analyses revealed the most-perturbed pathways following stroke and implied a structural dichotomy between microRNA and tRF target sets. Furthermore, lipopolysaccharide stimulation of murine RAW 264.7 cells and human CD14+ monocytes upregulated the top 6 stroke-perturbed tRFs, and overexpression of stroke-inducible tRF-22-WE8SPOX52 using an ssRNA mimic induced downregulation of immune regulator Z-DNA binding protein 1 (Zbp1). In summary, we identified a "changing of the guards" between RNA types that may systemically affect homeostasis in post-stroke immune responses, and pinpointed multiple affected pathways, which opens new venues for establishing therapeutics and biomarkers at the protein- and RNA-level.

中文翻译：

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转移RNA片段取代了胆碱能中风后免疫阻滞的microRNA调节剂

中风是导致死亡和残疾的主要原因。康复取决于炎症反应与免疫抑制之间的微妙平衡，从而缩小了大脑保护与易感性之间的界限。免疫反应的外周胆碱能阻滞可以微调这种免疫反应，但其分子调节剂尚不清楚。在这里，我们报告了缺血性卒中后两天测序的患者血液中小RNA类型的调节变化，包括大量降低microRNA水平和同时增加了针对胆碱能转录本的转移RNA片段（tRF）。基于电泳的大小选择，然后进行RT-qPCR，验证了卒中患者的一个独立队列中前6个上调的tRF，并且小而长RNA测序的独立数据集指出了对这些反应至关重要的免疫细胞亚群，CD14 +单核细胞参与胆碱能炎症反射。深入的小RNA靶向分析揭示了卒中后最受干扰的途径，并暗示了microRNA与tRF靶标集之间的结构二分法。此外，脂多糖刺激鼠RAW 264.7细胞和人类CD14 +单核细胞上调了前6个中风扰动的tRF，并使用ssRNA模拟诱导的免疫调节剂Z-DNA结合蛋白1（Zbp1）的下调诱导了中风诱导性tRF-22-WE8SPOX52的过表达。 ）。总而言之，我们确定了可能在卒中后免疫反应中系统性地影响体内平衡的RNA类型之间的“防卫变化”，并指出了多种受影响的途径，这为在蛋白质和RNA水平建立治疗和生物标记物提供了新的场所。