lnc-IL7R/DNMT1/Jmjd3通路在线粒体损伤相关分子模式介导的创伤性急性肺损伤的机制研究

Recently, lnc-IL7R, which is a long non-coding RNA (lncRNA) and rapidly induced by LPS, was shown to down-regulate LPS-induced inflammation. But the molecular mechanism is still undiscovered. Even though excessive inflammation is a hallmark of acute lung injury (ALI), whether or not lnc-IL7R got a role in the traumatic ALI is still unknown. Similar to LPS, mitochondrial damage-associated molecular patterns (MTDs)-induced inflammation is a critical component of traumatic ALI and it is logical to speculate that lnc-IL7R might be involved in MTDs-induced inflammation and ALI. We found that compare with trauma without ALI patients, lnc-IL7R in neutrophils of traumatic ALI patients was significantly decreased. Analogous to LPS, IL7R was also rapidly induced by MTDs in THP-1 and HBE cells and suppressed some inflammatory factors release. We further found that IL7R bind with DNA (cytosine-5)-methyltransferase 1 (DNMT1) and suppressed Jmjd3 expression, a key a histone H3K27 demethylase, by increasing DNA methylation in its promoter, where CpG occurs. As Jmjd3 is a “broad-spectrum” pro-inflammatory by decreasing histone methylation (H3K27me3) of numbers of inflammatory genes, IL7R negatively regulate MTDs-induced inflammation in this “feedback” way. Thus, we speculate that lnc-IL7R/DNMT1/Jmjd3 pathway is essential in the regulation of MTDs-induced inflammation and ALI. We aimed to make it clear that upon MTDs stimulation, MTDs-induced lnc-IL7R binds DNMT1, recruit it to Jmjd3 gene and increases DNA methylation of Jmjd3, which results in controlled inflammation. We will also detect lnc-IL7R and Jmjd3 promoter methylation in neutrophils of severe traumatic patients and evaluate the effect of lnc-IL7R abnormity on traumatic ALI and its prognosis. We hope that this study would provide some new evidence in the field of MTDs and traumatic ALI.

新近发现长非编码RNA（lncRNA）lnc-IL7R可抑制LPS所致炎症，但在创伤性急性肺损伤（ALI）的作用和机制尚不清楚。线粒体损伤相关分子模式（MTDs）介导的炎症是创伤性ALI的重要因素。我们发现：创伤性ALI患者中性粒细胞lnc-IL7R显著下调，lnc-IL7R在MTDs处理细胞中表达增加，并可抑制多种炎症因子表达，它可与DNA甲基化酶DNMT1结合，募集DNMT1调控Jmjd3（组蛋白H3K27me3去甲基化酶）启动子甲基化、下调Jmjd3表达、调控炎症。故我们提出假说：lnc-IL7R/DNMT1/Jmjd3通路调控MTDs介导的炎症和ALI。本课题拟明确lnc-IL7R募集DNMT1、调控Jmjd3在MTDs致炎症中的作用，并探索lnc-IL7R表达异常与创伤性 ALI 发生及预后的关系，为lncRNA在MTDs介导创伤性ALI的调控机制提供新依据。

线粒体损伤相关分子模式（mitochondrial damage-associated molecular patterns，MTDs）介导过度炎症反应是ARDS的重要发病原因之一，研究显示长非编码RNA（long non-coding RNA，lncRNA）lnc-IL7R是可下调炎症反应的上游分子之一，但目前对其在MTDs相关ARDS中的作用尚不明确。本研究显示，MTDs可显著上调THP-1细胞和小鼠肺组织炎症反应和lnc-IL7R表达，MTDs气管滴入ARDS动物模型中肺组织lnc-IL7R表达较高的小鼠死亡率显著下降，这提示lnc-IL7R的上调可能是MTDs刺激后的自我负反馈机制之一，同时体外研究显示抑制lnc-IL7R表达后并未直接影响MTDs相关炎症因子释放，这表明lnc-IL7R可能是通过其他分子间接调控MTDs相关炎症反应和肺组织损伤。进一步临床研究显示，ARDS患者血浆中lnc-IL7R表达显著低于健康对照组患者，并且与疾病严重程度和预后相关，这也支持lnc-IL7R可能是ARDS过度炎症反应和肺组织损伤负性调控因子之一。同时创伤患者lnc-IL7R表达也显著低于健康对照组，并且与创伤严重程度和MODS发生负相关，这也提示lnc-IL7R异常下调可能与创伤患者相关并发症发生相关。同时在本研究中探索了托泊替康对LPS相关ARDS和呼吸机相关ARDS的影响，结果显示托泊替康可通过抑制NF-kB通路减轻肺组织损伤和过度炎症反应。综合以上结果，本研究表明lnc-IL7R是MTDs相关炎症反应的负性调节因子之一，并且lnc-IL7R异常下调与ARDS患者和创伤患者不良预后相关。