Department of Medical Physiology, Texas A&M University College of Medicine, Temple, TX, 76504, USA.
Research, Central Texas Veterans Health Care System, Temple, TX, 76504, USA.
Lab Invest. 2018 Nov;98(11):1449-1464. doi: 10.1038/s41374-018-0093-9. Epub 2018 Jul 5.
Secretin receptor (SR), only expressed by cholangiocytes, plays a key role in the regulation of biliary damage and liver fibrosis. The aim of this study was to determine the effects of genetic depletion of SR in Mdr2 mice on intrahepatic biliary mass, liver fibrosis, senescence, and angiogenesis. 12 wk SR, Mdr2, and SR/Mdr2 mice with corresponding wild-type mice were used for the in vivo studies. Immunohistochemistry or immunofluorescence was performed in liver sections for (i) biliary expression of SR; (ii) hematoxylin and eosin; (iii) intrahepatic biliary mass by CK-19; (iv) fibrosis by Col1a1 and α-SMA; (v) senescence by SA-β-gal and p16; and (vi) angiogenesis by VEGF-A and CD31. Secretin (Sct) and TGF-β1 levels were measured in serum and cholangiocyte supernatant by ELISA. In total liver, isolated cholangiocytes or HSCs, we evaluated the expression of fibrosis markers (FN-1 and Col1a1); senescence markers (p16 and CCL2); microRNA 125b and angiogenesis markers (VEGF-A, VEGFR-2, CD31, and vWF) by immunoblots and/or qPCR. In vitro, we measured the paracrine effect of cholangiocyte supernatant on the expression of senescent and fibrosis markers in human hepatic stellate cells (HHSteCs). The increased level of ductular reaction, fibrosis, and angiogenesis in Mdr2 mice was reduced in SR/Mdr2 mice. Enhanced senescence levels in cholangiocytes from Mdr2 mice were reversed to normal in SR/Mdr2 mice. However, senescence was decreased in HSCs from Mdr2 mice but returned to normal values in SR/Mdr2 mice. In vitro treatment of HHSteCs with supernatant from cholangiocyte lacking SR (containing lower biliary levels of Sct-dependent TGF-β1) have decreased fibrotic reaction and increased cellular senescence. Sct-induced TGF-β1 secretion was mediated by microRNA 125b. Our data suggest that differential modulation of angiogenesis-dependent senescence of cholangiocytes and HSCs may be important for the treatment of liver fibrosis in cholangiopathies.
胆囊收缩素受体(SR)仅在胆管细胞中表达,在调节胆汁损伤和肝纤维化中起关键作用。本研究旨在确定在 Mdr2 小鼠中遗传耗尽 SR 对肝内胆管质量、肝纤维化、衰老和血管生成的影响。在体内研究中使用了 12 周龄的 SR、Mdr2 和 SR/Mdr2 小鼠及其相应的野生型小鼠。对肝组织切片进行免疫组织化学或免疫荧光染色,检测(i)SR 在胆汁中的表达;(ii)苏木精和伊红;(iii)CK-19 检测的肝内胆管质量;(iv)Col1a1 和 α-SMA 检测的纤维化;(v)SA-β-半乳糖和 p16 检测的衰老;(vi)VEGF-A 和 CD31 检测的血管生成。通过 ELISA 测量血清和胆管细胞上清液中的胆囊收缩素(Sct)和 TGF-β1 水平。在总肝、分离的胆管细胞或 HSCs 中,我们通过免疫印迹和/或 qPCR 评估纤维化标志物(FN-1 和 Col1a1)、衰老标志物(p16 和 CCL2)、microRNA 125b 和血管生成标志物(VEGF-A、VEGFR-2、CD31 和 vWF)的表达。在体外,我们测量了胆管细胞上清液对人肝星状细胞(HHSteCs)中衰老和纤维化标志物表达的旁分泌作用。在 Mdr2 小鼠中,胆管细胞 SR 的增加导致胆管反应、纤维化和血管生成增加,而在 SR/Mdr2 小鼠中则减少。在 Mdr2 小鼠中,胆管细胞的衰老水平增强,但在 SR/Mdr2 小鼠中恢复正常。然而,在 Mdr2 小鼠的 HSCs 中,衰老减少,但在 SR/Mdr2 小鼠中恢复正常。体外用缺乏 SR 的胆管细胞上清液(含有较低的 Sct 依赖的 TGF-β1 胆管水平)处理 HHSteCs,可减少纤维化反应并增加细胞衰老。Sct 诱导的 TGF-β1 分泌是由 microRNA 125b 介导的。我们的数据表明,胆管细胞和 HSCs 中依赖血管生成的衰老的差异调节可能是治疗胆管病肝纤维化的重要因素。