Key Points NI in the colon affects barrier function later in life. NI sensitizes the Mir155 promoter for aberrant epigenetic activation. miR-155 suppresses E-cadherin protein expression in the colonic epithelium. Altered intestinal epithelial integrity is an important susceptibility trait in inflammatory bowel disease (IBD), and early life stressors are reported to contribute to this disease susceptibility in adulthood. To identify disease mechanisms associated with early-life trauma that exacerbate IBD in adulthood, we used a “double-hit” neonatal inflammation (NI) and adult inflammation (AI) model that exhibits more severe mucosal injury in the colon later in life. In this study, we explore the underlying mechanisms of this aggravated injury. In rats exposed to both NI and AI, we found sustained increases in colonic permeability accompanied by significantly attenuated expression of the epithelial junction protein E-cadherin. Quantitative RT-PCR revealed a decreased Cdh1 (gene of E-cadherin) mRNA expression in NI + AI rats compared with NI or AI rats. Next, we performed microRNA microarrays to identify potential regulators of E-cadherin in NI + AI rats. We confirmed the overexpression of miR-155, a predicted regulator of E-cadherin, and selected it for further analysis based on reported significance in human IBD. Using ingenuity pathway analysis software, the targets and related canonical pathway of miR-155 were analyzed. Mechanistic studies identified histone hyperacetylation at the Mir155 promoter in NI + AI rats, concomitant with elevated RNA polymerase II binding. In vitro, E-cadherin knockdown markedly increased epithelial cell permeability, as did overexpression of miR-155 mimics, which significantly suppressed E-cadherin protein. In vivo, NI + AI colonic permeability was significantly reversed with administration of miR-155 inhibitor rectally. Our collective findings indicate that early-life inflammatory stressors trigger a significant and sustained epithelial injury by suppressing E-cadherin through epigenetic mechanisms.

中文翻译：

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新生儿损伤通过表观遗传抑制成年后的 E-钙粘蛋白来增加肠道渗透性

关键点 结肠中的 NI 会影响生命后期的屏障功能。NI 使 Mir155 启动子对异常表观遗传激活敏感。miR-155 抑制结肠上皮中的 E-钙粘蛋白表达。肠上皮完整性的改变是炎症性肠病 (IBD) 的一个重要易感性特征，据报道，早期生活压力会导致成年期这种疾病的易感性。为了确定与在成年期加剧 IBD 的早期创伤相关的疾病机制，我们使用了“双重打击”新生儿炎症 (NI) 和成人炎症 (AI) 模型，该模型在以后的生活中表现出更严重的结肠粘膜损伤。在这项研究中，我们探索了这种加重损伤的潜在机制。在暴露于 NI 和 AI 的大鼠中，我们发现结肠通透性持续增加，伴随着上皮连接蛋白 E-钙粘蛋白的表达显着减弱。定量 RT-PCR 显示，与 NI 或 AI 大鼠相比，NI + AI 大鼠的 Cdh1（E-钙粘蛋白基因）mRNA 表达降低。接下来，我们进行了 microRNA 微阵列，以确定 NI + AI 大鼠中 E-钙粘蛋白的潜在调节剂。我们证实了 miR-155（一种预测的 E-钙粘蛋白调节剂）的过度表达，并根据报告的在人类 IBD 中的显着性选择了它进行进一步分析。使用ingenuity通路分析软件，对miR-155的靶点及相关经典通路进行分析。机制研究确定了 NI + AI 大鼠 Mir155 启动子处的组蛋白高度乙酰化，伴随着 RNA 聚合酶 II 结合的升高。体外，E-钙粘蛋白敲低显着增加上皮细胞通透性，miR-155模拟物的过度表达也是如此，这显着抑制了E-钙粘蛋白蛋白。在体内，通过直肠施用 miR-155 抑制剂，NI + AI 结肠通透性显着逆转。我们的集体研究结果表明，生命早期的炎症应激源通过表观遗传机制抑制 E-钙粘蛋白，从而引发显着且持续的上皮损伤。