Zgheib Carlos, Hodges Maggie M, Hu Junyi, Liechty Kenneth W, Xu Junwang
Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
Department of Surgery, Division of Pediatric Surgery, Children's Hospital Colorado, Aurora, Colorado, United States of America.
PLoS One. 2017 May 11;12(5):e0177453. doi: 10.1371/journal.pone.0177453. eCollection 2017.
Type 2 diabetes mellitus is a complex, systemic metabolic disease characterized by insulin resistance and resulting hyperglycemia, which is associated with impaired wound healing. The clinical complications associated with hyperglycemia are attributed, in part, to the increased production of reactive oxygen species (ROS). Recent studies revealed that long non-coding RNAs (lncRNAs) play important regulatory roles in many biological processes. Specifically, lncRNA Lethe has been described as exhibiting an anti-inflammatory effect by binding to the p65 subunit of NFκB and blocking its binding to DNA and the subsequent activation of downstream genes. We therefore hypothesize that dysregulation of Lethe's expression plays a role in hyperglycemia-induced ROS production. To test our hypothesis, we treated RAW264.7 macrophages with low glucose (5 mM) or high glucose (25 mM) for 24h. High glucose conditions significantly induced ROS production and NOX2 gene expression in RAW cells, while significantly decreasing Lethe gene expression. Overexpression of Lethe in RAW cells eliminated the increased ROS production induced by high glucose conditions, while also attenuating the upregulation of NOX2 expression. Similar results was found also in non-diabetic and diabetic primary macrophage, bone marrow derived macrophage (BMM). Furthermore, overexpression of Lethe in RAW cells treated with high glucose significantly reduced the translocation of p65-NFkB to the nucleus, which resulted in decreased NOX2 expression and ROS production. Interestingly, these findings are consistent with the decreased Lethe gene expression and increased NOX2 gene expression observed in a mouse model of diabetic wound healing. These findings provide the first evidence that lncRNA Lethe is involved in the regulation of ROS production in macrophages through modulation of NOX2 gene expression via NFκB signaling. Moreover, this is the first report to describe a role of lncRNAs, in particular Lethe, in impaired diabetic wound healing. Further studies are warranted to determine if correction of Lethe expression in diabetic wounds could improve healing.
2型糖尿病是一种复杂的全身性代谢疾病，其特征为胰岛素抵抗及由此导致的高血糖，这与伤口愈合受损有关。高血糖相关的临床并发症部分归因于活性氧（ROS）生成增加。最近的研究表明，长链非编码RNA（lncRNA）在许多生物学过程中发挥重要的调节作用。具体而言，lncRNA Lethe已被描述为通过与NFκB的p65亚基结合并阻断其与DNA的结合以及随后下游基因的激活而发挥抗炎作用。因此，我们推测Lethe表达失调在高血糖诱导的ROS生成中起作用。为了验证我们的假设，我们用低葡萄糖（5 mM）或高葡萄糖（25 mM）处理RAW264.7巨噬细胞24小时。高糖条件显著诱导RAW细胞中ROS生成和NOX2基因表达，同时显著降低Lethe基因表达。在RAW细胞中过表达Lethe消除了高糖条件诱导的ROS生成增加，同时也减弱了NOX2表达的上调。在非糖尿病和糖尿病原代巨噬细胞、骨髓来源巨噬细胞（BMM）中也发现了类似结果。此外，在高糖处理的RAW细胞中过表达Lethe显著减少了p65-NFkB向细胞核的转位，从而导致NOX2表达和ROS生成减少。有趣的是，这些发现与糖尿病伤口愈合小鼠模型中观察到的Lethe基因表达降低和NOX2基因表达增加一致。这些发现提供了首个证据，即lncRNA Lethe通过NFκB信号通路调节NOX2基因表达参与巨噬细胞中ROS生成的调控。此外，这是第一份描述lncRNA，特别是Lethe，在糖尿病伤口愈合受损中作用的报告。有必要进一步研究确定纠正糖尿病伤口中Lethe的表达是否可以改善愈合。
