The mechanism of liver regeneration in response to continuous stretch in ECs

我们之前报道过门静脉栓塞（PVE）后窦内皮细胞（ECs）约150%的单轴持续拉伸可能是通过NF-kB激活介导的IL-6分泌引发肝脏再生的一个因素。然后，我们研究了在弹性硅胶膜上培养的内皮细胞，并进行了连续的单轴拉伸。我们的研究结果表明，持续拉伸诱导的IL-6分泌依赖于通过整合素的外向内信号传导，随后是PI3-K/PLC-gamma/PKC/NF-kB信号传导级联。此外，我们建立了非应激性门静脉结扎（nsPVL）大鼠模型，该模型在手术应激消退后进行结扎。全麻下剖腹手术后，将单丝缝线绕左门静脉打结，但不打结，两端分别穿过两侧。开腹7天后，通过牵拉结扎两端，收紧结扎形成PVL。生化分析显示，开腹手术应激在第7天消失。NF-kB和p-STAT3在nsPVL模型中呈双相表达（在0.5-1 h出现第一个高峰，在3-6 h出现第二个高峰）。IL-6基因在结扎后3小时显著升高。IL-6 mRNA在窦状上皮细胞中的表达主要在门静脉周围区增加。PVL后血清IL-6浓度迅速上升（3小时内），并持续升高至6小时。我们使用nsPVL模型的结果可能代表肝脏再生相关的信号模式（PVE→（窦内皮细胞）拉伸→NF→kB→IL-6→（肝细胞）STAT3→肝再生级联）。

We previously reported that an approximately 150% uni-axial sustained stretch in sinusoidal endothelial cells (ECs) after portal vein embolization (PVE) might be a trigger for liver regeneration via IL-6 secretion which is mediated by an activation of NF-kB. We then studied ECs cultured on an elastic silicone membrane and subjected to continuous uni-axial stretch. Our results indicate that continuous stretch-induced IL-6 secretion depends on outside-in signaling via integrins followed by a PI3-K/PLC-gamma/PKC/NF-kB signaling cascade.Furthermore, we developed a non-stress portal vein ligation (nsPVL) rat model, which performs the ligation after surgical stress is subsided. After laparotomy under general anesthesia, a monofilament suture was placed around the left portal vein and knotted, but not tied, and the two ends were delivered through each flank. Seven days after laparotomy, PVL was created by pulling the two ends of the ligature, tightening the ligature. Biochemical assays indicated that the surgical stress of laparotomy resolved on day 7. The expression pattern of NF-kB and p-STAT3 was biphasic (first peak at 0.5-1 h, second peak at 3-6 h) in nsPVL model. IL-6 gene significantly increased 3 h after ligation in the non-embolized lobes. An expression of IL-6 mRNA in the sinusoidal ECs increased predominantly at the periportal area. The serum IL-6 concentration rose rapidly (within 3 h) after PVL and remained elevated until 6 h. Our results using nsPVL model may represent liver regeneration-associated signal pattern (PVE→(sinusoidal endothelial cell) stretch→NF→kB→IL-6→(hepatocyte)STAT3→liver regeneration cascade).