The role of liver sinusoidal endothelial cells in liver remodeling after injury

Liver transplantation is the optimal treatment for patients with end-stage liver disease,metabolic liver diseases,and hepatic malignancies that are not amenable to resection.Hepatic ischemia-reperfusion injury(IRI)is the main problem in liver transplantation and liver resection,leading to parenchymal cell injury and organ dysfunction.The damage of liver sinusoidal endothelial cells(LSECs)is a critical event in IRI.LSECs work as an important regulating factor of liver regeneration after partial hepatectomy.This review primarily describes the mechanisms of LSECs injury in IRI and explores the roles of LSECs in liver regeneration,and briefly introduces the protective strategies targeting LSECs damaged in IRI.

Effects of ethanol on liver sinusoidal endothelial cells-fenestrae of rats

Important advances have been made in research into the mechanism of alcoholic liver disease (ALD) over the past few years,but the role of liver sinusoidal endothelial cell (LSEC) in ALD has not been elucidated adequately. This study was undertaken to investigate the effect of ethanol on fenestrae of LSECs in rats. METHODS: A rat model of alcoholic liver disease was established by means of direct intragastric instillation of ethanol. Fifty-five rats of experimental (35 rats) and control (20) groups were sacrificed at the end of 4,8,12 weeks respectively, and also at the end of 12-week abstinence. After heart perfusion, the liver tissue was fixed and stained with hematoxylin and eosin for observation of serial changes of LSEC-fenestrae under a transmission electron microscope. RESULTS: Normal LESC was flat with a nucleus and organelles arranged regularly. The distal cytoplasm displayed as a lamina with many fenestrae, lacking the basement membrane(BM) underneath the endothelium. At the end of 4-week alcohol feeding, the number of fenestrae decreased at the distal cytoplasm in some LSECs, without the formation of the BM underneath the endothelium. At the end of 8 weeks, the number of fenestrae decreased significantly or even disappeared. The BM began to develop incompletely underneath the endothelium, while the active fibroblast appeared. At the end of 12 weeks, the number of fenestrae decreased more significantly and the complete BM could even be seen. But the changes were mostly limited in the single or adjoining sinus, and fibrosis was scarcely formed. At the end of 12-week abstinence, defenestration and formation of the endothelial BM lightened significantly. CONCLUSIONS:Defenestration and formation of the BM in LSECs develop gradually with the chronic stimulation of ethanol. Hepatic sinusoidal capillarization and fibrosis will be seen if their state is more serious. These early changes, i. e., limited and regional defenestration and capillarization may be the basis of alcoholic peri-fibrosis. This kind of he- patic fibrosis is reversible after removal of etiological factors.

Discussion on Serum Technique and Cryopreservation Technique in the Culture of Liver Sinusoidal Endothelial Cells

Hepatic sinusoidal endothelial cells are a kind of highly differentiated cells in hepatic sinusoids, which play an important role in the occurrence and development of liver fibrosis. Hepatic sinusoidal endothelial cells are often used in the study of liver fibrosis. In the process of culturing liver sinusoidal endothelial cells, the treatment of serum for culture and cryopreservation of cells are relatively complicated and error-prone. If the technical details of serum treatment and cell cryopreservation are not handled properly, it will have a more obvious effect on the effect of hepatic sinusoidal endothelial cell culture. We have gained experience in the theoretical study of liver fibrosis and the operation of cell culture experiments, and this paper summarized the details of liver sinusoidal endothelial cell culture such as the problems of serum preservation, thawing, precipitates and heat inactivation, as well as methods and precautions for cell cryopreservation.

Effects of Astragalus Polysaccharide on Mechanical Characterization of Liver Sinusoidal Endothelial Cells by Atomic Force Microscopy at Nanoscale

Objective： To study the effects of Astragalus polysaccharide （APS）, the primary effective component of the Chinese herb medicine Astragalus membranaceus （frequently used for its anti-hepatic fibrosis effects）, on nanoscale mechanical properties of liver sinusoidal endothelial cells （SECs）. Methods： Using endothelial cell medium as the control, 5 experimental groups were established utilizing different concentrations of APS, i.e. 12.5, 25, 50, 100, and 200μg/mL. By using atomic force microscopy along with a microcantilever modified with a silicon dioxide microsphere as powerful tools, the value of Young＇s modulus in each group was calculated. SAS 9.1 software was applied to analyze the values of Young＇s modulus at the pressed depth of 300 nm. Environmental scanning electron microscopy was performed to observe the surface microtopography of the SECs. Results： The value of Young＇s modulus in each APS experimental group was significantly greater than that of the control group： as APS concentration increased, the value of Young＇s modulus presented as an increasing trend. The difference between the low-concentration （12.5 and 25 μg/mL） and high-concentration （200μg/mL） groups was statistically significant （P〈0.05）, but no significant differences were observed between moderate-concentration （50 and 100μg/mL） groups versus low- or high-concentration groups （P〉0.05）. Surface topography demonstrated that APS was capable of increasing the total area of fenestrae. Conclusions： The values of Young＇s modulus increased along with increasing concentrations of APS, suggesting that the stiffness of SECs increases gradually as a function of APS concentration. The observed changes in SEC mechanical properties may provide a new avenue for mechanistic rasearch of anti-hepatic fibrosis treatments in Chinese medicine.

Mechanotransduction of liver sinusoidal endothelial cells under varied mechanical stimuli

Liver sinusoidal endothelial cells(LSECs)are the gatekeeper of liver to maintain hepatic homeostasis.They are formed into the highly specialized endothelium between vascular lumen and the space of Disse and are mechanosensitive to respond varied microenvironments.Shear stress and mechanical stretch induced by blood perfusion and substrate stiffness enhancement derived from deposition of extracellular matrix(ECM)are major mechanical stimuli that surround LSECs.This review introduces how LSECs respond to the external forces in both physiological and pathological cases and what is the interplay of LSECs with other hepatic cells.Molecular mechanisms that potentiate LSECs mechanotransduction are also discussed.

Effect of Qishen decoction on dedifferentiation of sinusoidal endothelial cells by autophagy

Objective:To observe the effect of Qishen decoction on dedifferentiation and autophagy of liver sinusoid endothelial cells(LSEC);Methods:LSEC were randomly divided into the control group,model group,Qishen Decoction low,medium,high dose group,and inhibitor group.The model was induced by 100μg/ml oxidized low-density lipoprotein(oxLDL)for 24 hours,and the corresponding drugs or medicated serum were given for intervention.The expression levels of VEGFR2 and ET1 were detected by RT-qPCR and immunofluorescence staining,the ultrastructure of LSEC was detected by transmission electron microscopy,the content of NO was detected by ELISA,the expression levels of autophagy related proteins(LC3BI,LC3BⅡand p62)and endothelial function related proteins(eNOS and p-eNOS)were detected by western blot;Results:The results of transmission electron microscopy showed that Qishen decoction medicated serum could increase the number of fenestra and autophagy in LSEC cells,and inhibit the formation of basement membrane under endothelium.Compared with the model group,Qishen decoction medicated serum could significantly up-regulate the expression level of VEGFR2 mRNA and protein in LSEC,down regulate the expression level of ET1 mRNA and protein,the difference was statistically significant(P<0.05).In addition,Qishen decoction medicated serum could significantly increase the expression of LC3BII,p-eNOS,eNOS protein and the ratio of LC3BII/LC3BI,p-eNOS/eNOS,and reduce the expression of LC3BI and p62 protein in LSEC,which is statistically significant compared with the model group(P<0.05).Conclusion:Qishen decoction can inhibit the dedifferentiation of LSEC by promoting the autophagy level of LSEC,and then play an anti-fibrosis role.

Neuropilin-1: A feasible link between liver pathologies and COVID-19

The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)pandemic has a tremendous impact on the health of millions of people worldwide.Unfortunately,those suffering from previous pathological conditions are more vulnerable and tend to develop more severe disease upon infection with the new SARS-CoV-2.This coronavirus interacts with the angiotensin-converting enzyme 2 receptor to invade the cells.Recently,another receptor,neuropilin-1(NRP-1),has been reported to amplify the viral infection.Interestingly,NRP-1 is expressed in nonparenchymal liver cells and is related to and upregulated in a wide variety of liver-related pathologies.It has been observed that SARS-CoV-2 infection promotes liver injury through several pathways that may be influenced by the previous pathological status of the patient and liver expression of NRP-1.Moreover,coronavirus disease 2019 causes an inflammatory cascade called cytokine storm in patients with severe disease.This cytokine storm may influence liver sinusoidal-cell phenotype,facilitating viral invasion.In this review,the shreds of evidence linking NRP-1 with liver pathologies such as hepatocellular carcinoma,liver fibrosis,nonalcoholic fatty liver disease and inflammatory disorders are discussed in the context of SARS-CoV-2 infection.In addition,the involvement of the infection-related cytokine storm in NRP-1 overexpression and the subsequent increased risk of SARS-CoV-2 infection are also analyzed.This review aims to shed some light on the involvement of liver NRP-1 during SARSCoV-2 infection and emphasizes the possible involvement this receptor with the observed liver damage.

Amygdalin Ameliorates Liver Fibrosis through Inhibiting Activation of TGF-β/Smad Signaling

Objective:To observe the effect of amygdalin on liver fibrosis in a liver fibrosis mouse model,and the underlying mechanisms were partly dissected in vivo and in vitro.Methods:Thirty-two male mice were randomly divided into 4 groups,including control,model,low-and high-dose amygdalin-treated groups,8 mice in each group.Except the control group,mice in the other groups were injected intraperitoneally with 10%carbon tetrachloride(CCl4)-olive oil solution 3 times a week for 6 weeks to induce liver fibrosis.At the first 3 weeks,amygdalin(1.35 and 2.7 mg/kg body weight)were administered by gavage once a day.Mice in the control group received equal quantities of subcutaneous olive oil and intragastric water from the fourth week.At the end of 6 weeks,liver tissue samples were harvested to detect the content of hydroxyproline(Hyp).Hematoxylin and eosin and Sirius red staining were used to observe the inflammation and fibrosis of liver tissue.The expressions of collagenⅠ(Col-Ⅰ),alpha-smooth muscle actin(α-SMA),CD31 and transforming growth factorβ(TGF-β)/Smad signaling pathway were detected by immunohistochemistry,quantitative real-time polymerase chain reaction and Western blot,respectively.The activation models of hepatic stellate cells,JS-1and LX-2 cells induced by TGF-β1 were used in vitro with or without different concentrations of amygdalin(0.1,1,10μmol/L).The effect of different concentrations of amygdalin on the expressions of liver sinusoidal endothelial cells(LSECs)dedifferentiation markers CD31 and CD44 were observed.Results:High-dose of amygdalin significantly reduced the Hyp content and percentage of collagen positive area,and decreased the mRNA and protein expressions of Col-Ι,α-SMA,CD31 and p-Smad2/3 in liver tissues of mice compared to the model group(P<0.01).Amygdalin down-regulated the expressions of Col-Ⅰandα-SMA in JS-1 and LX-2 cells,and TGFβR1,TGFβR2 and p-Smad2/3 in LX-2 cells compared to the model group(P<0.05 or P<0.01).Moreover,1 and 10μmol/L amygdalin inhibited the mRNA and protein expressions of CD31 in LSECs and increased CD44 expression compared to the model group(P<0.05 or P<0.01).Conclusions:Amygdalin can dramatically alleviate liver fibrosis induced by CCl4 in mice and inhibit TGF-β/Smad signaling pathway,consequently suppressing HSCs activation and LSECs dedifferentiation to improve angiogenesis.

Xiayuxue Decoction(下瘀血汤)Attenuates Hepatic Stellate Cell Activation and Sinusoidal Endothelium Defenestration in CCI_4-Induced Fibrotic Liver of Mice

Objective： To investigate the effects of ancient Chinese medical formula Xiayuxue Decoction （下瘀血汤, XYXD） on activation of hepatic stellate cells （HSCs） and defenestration of sinusoidal endothelial cells （SECs） in CCI4-induced fibrotic liver of mice. Methods： High performance liquid chromatography was used to identify the main components of XYXD and control the quality of extraction. C57BL/6 mice were induced liver fibrosis by CCI4 exposure and administered with XYXD for 6 weeks simultaneously. Liver tissue was investigated by hematoxylin-eosin and Sirius-red staining. Sinusoidal fenestrations were observed by scanning electronic microscopy and fluorescent immunohistochemistry of PECAM-1 （CD31）. Whole liver lysates were detected of α-smooth muscle actin （α-SMA） and type-I collagen by Western blot. Primary rat HSCs-T6 cells were analyzed by detecting α-SMA, F-actin, DNA fragmentation through confocal microscopy, Western blot, terminal-deoxynucleoitidyl transferase mediated nick end labeling （TUNEL） assay and cellomics arrayscan, respectively. Results： Amygdalin and emodin in XYXD were identified. XYXD （993 mg/kg） inhibited Sirius red positive area up to 70.1% （P〈0.01）, as well as protein levels of α-SMA and type- I collagen by 42.0% and 18.5% （P〈0.05） respectively. In vitro, XYXD （12.5 μg/mL, 50 μg/mL） suppressed the activation of HSCs and reversed the myofibroblastic HSCs into quiescent, demonstrated as inhibition of fluorescent F-actin by 32.3% and 46.6% （P〈0.05）. Besides, XYXD induced the apoptosis of HSC-T6 cells by 20.0% （P〈0.05） and 49.5% （P〈0.01）, evidenced by enhanced TUNEL positivity. Moreover, ultrastructural observation suggested XYXD inhibited defenestration of SECs, which was confirmed by 31.1% reduction of protein level of CD31 （P〈0.05）. Conclusions： XYXD inhibited both HSCs activation and SECs defenestration which accompany chronic liver injuries. These data may help to understand the underlying mechanisms of XYXD for prevetion of chronic liver diseases.

Research Progress and Research Ideas on Anti-hepatic Fibrosis and Promoting Blood Circulation and Removing Blood Stasis of the National Drug Plumbapin Based on W-P Body

Hepatic sinusoidal endothelial cells(HSEC)are the most important cells that constitute the microcirculation barrier of liver.Clinically,W-P bodies have been detected in the HSEC cells of most patients with liver fibrosis,and these bodies have become the synthesis and storage sites of vW factor,ET-1 and other factors of liver fibrosis;during pathological stimulation,W-P bodies will excrete the above factors into the cytoplasm,which can make the structure and function of HSEC maladjusted,cause the disturbance of liver microcirculation,and aggravate the process of liver fibrosis.However,previous studies have found that Plumbagin,the active ingredient of Guangxi specialty ethnic medicine,has the definite function of promoting blood circulation and removing blood stasis and anti-liver fibrosis,but its mechanism is not clear.In this study,the research progress of the above problems was reviewed,and further research ideas were derived from it as follows:the role of Plumbagin in promoting blood circulation and removing blood stasis and anti-liver fibrosis is produced by affecting the formation quantity of W-P bodies,affecting the synthesis and storage of the contents of W-P bodies,and interfering with their exocytosis ability.

Precise delivery of obeticholic acid via nanoapproach for triggering natural killer T cell-mediated liver cancer immunotherapy

Primary bile acids were reported to augment secretion of chemokine(C-X-C motif)ligand16(CXCL16)from liver sinusoidal endothelial cells(LSECs)and trigger natural killer T(NKT)cellbased immunotherapy for liver cancer.However,abundant expression of receptors for primary bile acids across the gastrointestinal tract overwhelms the possibility of using agonists against these receptors for liver cancer control.Taking advantage of the intrinsic property of LSECs in capturing circulating nanoparticles in the circulation,we proposed a strategy using nanoemulsion-loaded obeticholic acid(OCA),a clinically approved selective farnesoid X receptor(FXR)agonist,for precisely manipulating LSECs for triggering NKT cell-mediated liver cancer immunotherapy.The OCA-nanoemulsion(OCA-NE)was prepared via ultrasonic emulsification method,with a diameter of 184 nm and good stability.In vivo biodistribution studies confirmed that the injected OCA-NE mainly accumulated in the liver and especially in LSECs and Kupffer cells.As a result,OCA-NE treatment significantly suppressed hepatic tumor growth in a murine orthotopic H22 tumor model,which performed much better than oral medication of free OCA.Immunologic analysis revealed that the OCA-NE resulted in augmented secretion of CXCL16 and IFN-g,as well as increased NKT cell populations inside the tumor.Overall,our research provides a new evidence for the antitumor effect of receptors for primary bile acids,and should inspire using nanotechnology for precisely manipulating LSECs for liver cancer therapy.

The role of the Notch signaling pathway in liver injury and repair

This review aims to compile recent advances regarding the significance of Notch signaling in different types of intrahepatic cells during liver injury and repair.The functions of Notch signaling in regulating cell development,fate decisions,and organ homeostasis have been widely acknowledged.Notch is also expressed and activated in hepatocytes,macrophages,liver sinusoidal endothelial cells,endothelial progenitor cells,and hepatic progenitor cells during the process of development,injury,inflammation,fibrosis,and carcinoma.During acute/chronic liver injury,Notch interacts with many signaling pathways that are involved in liver repair.Recent research,including ours,has confirmed the crucial role of Notch signaling in modulating the function of diverse intrahepatic cells during liver injury and reconstruction.Thus,Notch signaling may serve as a potential therapeutic target for liver diseases.