PDF(Pubmed)
Abstract：
The incidence rate of ulcerative colitis (UC) is increasing annually, and glucocorticoid (GC) resistance (GCR) is a common cause of UC-induced remission failure. Our previous studies have shown that the expression of miR-642a-5p is downregulated in UC with GCR, suggesting that miR-642a-5p may be related to the GC response. Therefore, we investigated the mechanism by which miR-642a-5p regulates the GC response in THP-1 cells. We found that after treatment with miR-642a-5p mimics and DEX, the expression levels of glucocorticoid receptor (GR) in the nucleus and NF-κB p65 and p50 in the cytoplasm were increased (P < 0.05). miR-642a-5p mimics transfected into THP-1 cells could synergize with dexamethasone (DEX) to reduce lipopolysaccharide (LPS)-induced inflammatory factor levels such as TNF-α, IL-1β, IL-6 and IL-12 (P < 0.05). Bioinformatics analysis and luciferase reporter assays confirmed that TLR4 is a target gene of miR-642a-5p. miR-642a-5p mimic pretreatment enhanced the inhibitory effect of DEX on TLR4 induced by LPS and inhibited the expression of TLR4 on the cell surface (P < 0.05). Additionally, miR-642a-5p further prevented the nuclear import of NF-κB P65 and inhibited the phosphorylation of ERK, p38 and JNK. These results suggest that miR-642a-5p can inhibit the inflammation by suppressing the TLR4 signalling pathway in THP-1 cells. It also highlights the TLR4 signalling pathway as a potential therapeutic target in anti-inflammation.
摘要：
溃疡性结肠炎(UC)的发病率逐年上升,糖皮质激素（GC）抵抗（GCR）是UC诱导的缓解失败的常见原因。我们之前的研究表明，miR-642a-5p的表达在UC伴GCR中下调，提示miR-642a-5p可能与GC反应有关。因此,我们研究了miR-642a-5p调节THP-1细胞GC反应的机制.我们发现用miR-642a-5p模拟物和DEX治疗后，细胞核内糖皮质激素受体(GR)和细胞质内NF-κBp65、p50的表达水平均升高(P<0.05)。转染THP-1细胞的miR-642a-5p模拟物可以协同地塞米松(DEX)降低脂多糖(LPS)诱导的TNF-α等炎症因子水平,IL-1β,IL-6和IL-12(P<0.05)。生物信息学分析和荧光素酶报告基因检测证实TLR4是miR-642a-5p的靶基因。miR-642a-5p模拟物预处理可增强DEX对LPS诱导的TLR4的抑制作用,抑制细胞表面TLR4的表达(P<0.05)。此外,miR-642a-5p进一步阻止NF-κBP65的核输入，抑制ERK的磷酸化，P38和JNK。这些结果表明miR-642a-5p可以通过抑制THP-1细胞中的TLR4信号通路来抑制炎症。它还强调了TLR4信号通路作为抗炎的潜在治疗靶标。
