肝纤维化中肾素-血管紧张素的作用研究进展

在肝损伤中,肝星状细胞是公认的主要细胞外基质生成细胞,导致肝纤维发生有很多关键因素。在这些因素中,肾素-血管紧张素系统起着重要的作用。已发现的ACE-AngⅡ-AT1R受体轴具有致肝纤维化的作用,ACE2-Ang(1-7)-Mas受体轴具有抗肝纤维化的作用,两者相互作用调节肝纤维化的进程。该文旨在对近几年这方面的研究做一综述。     

Overexpression of Hepcidin Alleviates Steatohepatitis and Fibrosis in a Diet-induced Nonalcoholic Steatohepatitis

Background and AimsIron overload can contribute to the progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH). Hepcidin (Hamp), which is primarily synthesized in hepatocytes, is a key regulator of iron metabolism. However, the role of Hamp in NASH remains unclear. Therefore, we aimed to elucidate the role of Hamp in the pathophysiology of NASH.MethodsMale mice were fed a choline-deficient L-amino acid-defined (CDAA) diet for 16 weeks to establish the mouse NASH model. A choline-supplemented amino acid-defined (CSAA) diet was used as the control diet. Recombinant adeno-associated virus genome 2 serotype 8 vector expressing Hamp (rAAV2/8-Hamp) or its negative control (rAAV2/8-NC) was administered intravenously at week 8 of either the CDAA or CSAA diet.ResultsrAAV2/8-Hamp treatment markedly decreased liver weight and improved hepatic steatosis in the CDAA-fed mice, accompanied by changes in lipogenesis-related genes and adiponectin expression. Compared with the control group, rAAV2/8-Hamp therapy attenuated liver damage, with mice exhibiting reduced histological NAFLD inflammation and fibrosis, as well as lower levels of liver enzymes. Moreover, α-smooth muscle actin-positive activated hepatic stellate cells (HSCs) and CD68-postive macrophages increased in number in the CDAA-fed mice, which was reversed by rAAV2/8-Hamp treatment. Consistent with the in vivo findings, overexpression of Hamp increased adiponectin expression in hepatocytes and Hamp treatment inhibited HSC activation.ConclusionsOverexpression of Hamp using rAAV2/8-Hamp robustly attenuated liver steatohepatitis, inflammation, and fibrosis in an animal model of NASH, suggesting a potential therapeutic role for Hamp.     

全反式维甲酸对肝星状细胞活化及氧化应激的作用和机制探索

目的 探讨全反式维甲酸（ATRA）对肝星状细胞（HSCs）活化及氧化应激的作用和潜在机制。方法 应用10 ng/ml的血小板源性生长因子（PDGF-bb）诱导HSCs活化,以5 μmol/L剂量的ATRA处理48 h。检测细胞生长活力和表型标志物表达的变化,评价ATRA对HSCs活化的影响;检测细胞内活性氧（ROS）、还原型谷胱甘肽（GSH）和丙二醛（MDA）、抗氧化基因表达的变化,评价ATRA对HSCs氧化应激的影响;检测自噬标志物表达和自噬流的变化,评价ATRA对HSCs自噬活性的影响。结果 与PDGF-bb组相比,ATRA处理的HSCs生长活力显著降低（P<0.01）,α-SMA和Collagen I蛋白的表达明显减少（P<0.01）,细胞内ROS和MDA显著减少（P<0.01）,GSH显著增加（P<0.01）,抗氧化基因NRF2、HO-1和ATF4的表达明显增加（P<0.01）;同时自噬标志物Beclin 1和LC3 II/I的表达明显减少（P<0.01）,自噬流信号显著降低。结论 ATRA显著抑制PDGF-bb诱导的HSCs活化,降低HSCs的氧化应激水平和自噬活性,对肝纤维化的防治具有潜在应用价值。     

Notch1通过非经典的Notch信号通路调节胰腺星形细胞的活化

目的:探讨Notch1在胰腺星形细胞(pancreatic stellate cells,PSCs)活化中的作用。方法:利用免疫组织化学法与免疫荧光双标法检测Notch1在人胰腺导管腺癌(pancreatic ductal adenocarcinoma,PDAC)组织的表达情况;原代分离培养小鼠PSCs,利用油红O染色、Western blot及RT-qPCR法对其进行鉴定,并利用Western blot及RT-qPCR检测Notch1及其下游关键分子HES1的表达情况;转染Notch1小干扰RNA(Notch1 siRNA)至小鼠PSCs后,利用Western blot检测α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)、纤连蛋白(fibronectin)、I型胶原(collagen typeⅠ,ColⅠ)、Notch1及HES1的表达情况;利用划痕实验与CCK-8实验检测Notch1 siRNA对小鼠PSCs迁移与细胞活力的影响。结果:免疫组化与免疫荧光双标染色结果显示,Notch1表达在α-SMA阳性的PDAC间质细胞中;成功培养了小鼠PSCs细胞,且...     

Receptor-specific TRAIL as a means to achieve targeted elimination of activated hepatic stellate cells

Activated hepatic stellate cells (HSCs) are known to play a central role in liver fibrosis and their elimination is a crucial step toward the resolution and reversion of liver fibrosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a molecule that may contribute to the apoptotic removal of activated HSC through binding to its dedicated receptors. In the present study, we investigated the potential application of recombinant receptor-specific TRAIL proteins in the efficient elimination of activated HSCs. Our finding revealed differential contribution of TRAIL receptors among HSCs populations with activated hepatic stellate cells expresses more TRAIL receptors DR5. In vitro treatment of activated HSCs with DR5-specific or wild-type TRAIL variants induced a significant reduction in viability and extracellular matrix production, whereas no significant decrease in viability was associated with the treatment of cells by DR4-specific TRAIL. Our analysis indicate the successful application of the DR5 receptor-specific TRAIL variant in the targeted elimination of activated HSCs via interference with collagen production and simultaneous induction of apoptosis via activation of the caspase pathway. DR5 receptor-specific TRAIL may thus represent a new therapeutic compound for the treatment of liver fibrosis.     

Membrane potential‐dependent integration of synaptic inputs in entorhinal stellate neurons

Stellate cells (SCs) of the medial entorhinal cortex exhibit robust spontaneous membrane‐potential oscillations (MPOs) in the theta (4–12 Hz) frequency band as well as theta‐frequency resonance in their membrane impedance spectra. Past experimental and modeling work suggests that these features may contribute to the phase‐locking of SCs to the entorhinal theta rhythm and may be important for forming the hexagonally tiled grid cell place fields exhibited by these neurons in vivo. Among the major biophysical mechanisms contributing to MPOs is a population of persistent (non‐inactivating or slowly inactivating) sodium channels. The resulting persistent sodium conductance (G_NaP) gives rise to an apparent increase in input resistance as the cell approaches threshold. In this study, we used dynamic clamp to test the hypothesis that this increased input resistance gives rise to voltage‐dependent, and thus MPO phase‐dependent, changes in the amplitude of excitatory and inhibitory post‐synaptic potential (PSP) amplitudes. We find that PSP amplitude depends on membrane potential, exhibiting a 5–10% increase in amplitude per mV depolarization. The effect is larger than—and sums quasi‐linearly with—the effect of the synaptic driving force, V ‐ E_syn. Given that input‐driven MPOs 10 mV in amplitude are commonly observed in MEC stellate cells in vivo, this voltage‐ and phase‐dependent synaptic gain is large enough to modulate PSP amplitude by over 50% during theta‐frequency MPOs. Phase‐dependent synaptic gain may therefore impact the phase locking and phase precession of grid cells in vivo to ongoing network oscillations. © 2014 Wiley Periodicals, Inc.