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

我们先前报道，门静脉栓塞术(PVE)后，肝窦内皮细胞(ECs)大约150%的单轴持续拉伸可能是通过分泌IL-6来触发肝再生的，而IL-6是由核因子-kB激活所介导的。然后，我们研究了在弹性硅胶膜上培养的内皮细胞，并受到连续的单轴拉伸。我们的结果表明，持续拉伸诱导的IL-6分泌依赖于整合素的内外信号转导，随后是PI3-K/PLC-Gamma/PKC/NF-kB信号级联。此外，我们建立了一种无应激门静脉结扎(NsPVL)大鼠模型，在手术应激消退后进行结扎。在全身麻醉下剖腹手术后，将单丝缝合在门静脉左支周围，打结，但不打结，两端分别从两侧送出。剖腹手术7天后，通过拉动结扎的两端，收紧结扎，形成PVL。在nsPVL模型中，NF-kB和p-STAT3的表达呈双相性(0.5~1h出现第一个高峰，3~6h出现第二个高峰)。结扎后3h，非栓塞侧肺叶IL-6基因表达显著升高。在肝窦内皮细胞中，IL-6mRNA的表达主要集中在汇管区。血清IL-6浓度在PVL后3h内迅速升高，并持续升高至6h，我们的结果可能代表了肝再生相关的信号模式(PVE→(正弦内皮细胞)Stretch→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).