Liver Sinusoidal Endothelial Cell Injury Research Articles

Autotaxin is a potential predictive marker for the development of veno-occlusive disease/sinusoidal obstruction syndrome after allogeneic hematopoietic cell transplantation.

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT), and stratification of the high-risk group before transplantation is significant. Serum autotaxin (ATX) levels have been reported to increase in patients with liver fibrosis caused by metabolic inhibition from liver sinusoidal endothelial cells. Considering that the pathophysiology of VOD/SOS begins with liver sinusoidal endothelial cell injury, an increase in serum ATX levels may precede the onset of VOD/SOS. A retrospective study with 252 patients, including 12 patients with VOD/SOS, who had received allo-HCT was performed. The cumulative incidence of VOD/SOS was higher in the group with serum ATX levels before conditioning (baseline ATX) above the upper reference limit (high ATX group, p < 0.001), and 1-year cumulative incidences were 22.7% (95% confidence interval [95%CI], 3.1-42.4%) and 3.5% (95%CI, 1.1-5.8%), respectively. In the multivariate analysis, elevated baseline ATX was identified as an independent risk factor for VOD/SOS development and showed an additive effect on the predictive ability of known risk factors. Furthermore, the incidence of VOD/SOS-related mortality was greater in the high ATX group (16.7% vs. 1.3%; p = 0.005). Serum ATX is a potential predictive marker for the development of VOD/SOS.

Inhibition of 15-prostaglandin dehydrogenase attenuates acetaminophen-induced liver injury via suppression of apoptosis in liver endothelial cells

Hepatic microvascular disruption caused by injury to liver sinusoidal endothelial cells (LSECs) is an aggravating factor for drug-induced liver injury (DILI). It is suggested that prostaglandin E2 (PGE2) may be able to attenuate LSEC injury. However, it is also known that 15-keto PGE2, a metabolite of PGE2 produced by 15-prostaglandin dehydrogenase (15-PGDH) that is not a ligand of PGE2 receptors, suppresses inflammatory acute liver injury as a ligand of peroxisome proliferator-activated receptor γ. In this study, we aimed to understand whether 15-PGDH activity is essential for preventing DILI by suppressing hepatic microvascular disruption in a mouse model of acetaminophen (APAP)-induced liver injury. To inhibit 15-PGDH activity prior to APAP-induced LSEC injury, we administered the 15-PGDH inhibitor, SW033291, 1 h before and 3 h after APAP treatment. We observed that LSEC injury preceded hepatocellular injury in APAP administered mice. Hepatic endogenous PGE2 levels did not increase up till the initiation of LSEC injury but rather increased after hepatocellular injury. Moreover, hepatic 15-PGDH activity was downregulated in APAP-induced liver injury. The inhibition of 15-PGDH attenuated LSEC injury and subsequently hepatic injury by inhibiting apoptosis in APAP administered mice. Our in vitro studies also suggested that PGE2 inhibited APAP-induced apoptosis via the EP4/PI3K pathway in endothelial cells. Therefore, a decrease in 15-PGDH activity would be beneficial for preventing APAP-induced liver injury by attenuating LSEC injury.

Melatonin attenuates monocrotaline-induced hepatic sinusoidal obstruction syndrome in rats via activation of Sirtuin-3.

Melatonin possesses potent hepatoprotective properties, but it remains to be elucidated whether melatonin has a therapeutic effect on monocrotaline (MCT)-induced hepatic sinusoidal obstruction syndrome (HSOS). In this study, male Sprague Dawley rats were intraperitoneally injected with melatonin or the same volume of vehicle at 0 and 24 h after MCT intragastric administration. Next, hematoxylin-eosin staining and electron microscopy were performed to evaluate the hepatic sinusoidal injury of rats. Endothelial cell marker RECA-1 was observed by immunohistochemistry. Hepatic oxidative stress was analyzed by detecting malondialdehyde, glutathione S-transferase, and reactive oxygen species. Assessment of liver function was carried out byanalysis of serum aspartate aminotransferase, alanine aminotransferase, total bilirubin, and albumin levels. Real-time polymerase chain reaction and Western blot analysis were used to identifyliver Sirtuin-3 (SIRT3) and active matrix metallopeptidase 9 (MMP-9) expression. Besides, liver sinusoidal endothelial cells (LSECs) were used for the in vitro functional verification experiment. Specifically, liver histology of the melatonin-treated groups showed that the pathological damages caused by MCT were significantly attenuated, total HSOS scores were decreased, and the elevation of serum hyaluronic acid observed in the model group was also reduced. Moreover, melatonin treatment also improved the survival of rats after partial hepatectomy. Administration of melatonin ameliorated MCT-induced LSECs injury, hepatic oxidative stress, and hepatic dysfunction. Furthermore, melatonin treatment increased SIRT3 expression while attenuating MMP-9 activity in liver tissues. Cell experiment also demonstrated that SIRT3 might mediate the protective effect of melatonin on LSECs. Collectively, our study provided the potential rationale for the application of melatonin for the prevention of MCT-induced HSOS.

Gut-Liver Axis: Liver Sinusoidal Endothelial Cells Function as the Hepatic Barrier in Colitis-Induced Liver Injury.

BackgroundBased on the gut–liver axis theory, a leaky gut can aggravate liver injury. However, clinical studies suggest that although gut mucosa damage is commonly observed in inflammatory bowel disease (IBD), it seldom leads to severe liver injury. We hypothesize that there is a hepatic barrier in the gut–liver axis, which protects the liver against gut-derived invasive factors.MethodsColitis was induced by dextran sulfate sodium (DSS) in eight different liver injury models in Sprague–Dawley rats. Liver sinusoidal endothelial cell (LSEC) injury was evaluated by a scanning and transmission electron microscope. Neutrophils were depleted by injection of anti-rat polymorphonuclear serum. Two pneumonia models were also induced to investigate the mechanism of neutrophil recruitment and activation. LSECs isolated from rat liver were used to investigate the effect on neutrophil recruitment and activation.ResultsAmong eight liver injury models, DSS colitis had no effect on liver injury in three models with normal LSECs. In the other five models with LSEC rupture, liver injury was significantly exacerbated by colitis, and increased hepatic neutrophil accumulation was observed. When neutrophils were depleted, colitis-induced liver injury was significantly attenuated. In pneumonia, liver injury, and colitis models, the level of CXCL1 correlated with the recruitment of neutrophils in different tissues, while DSS colitis and LSEC injury synergistically contributed to increased CXCL1 expression in the liver. In colitis-induced liver injury, neutrophils were activated in the liver. Injured LSECs showed both structural and functional changes, with significantly increased expression of CXCL1 and TNF-α under the stimulation of lipopolysaccharide (LPS). The combination of gut-derived LPS and LSEC-derived TNF-α led to the activation of neutrophils, characterized by enhanced production of reactive oxygen species, pro-inflammatory cytokines, and the formation of neutrophil extracellular traps.ConclusionLSECs constitute a vitally important barrier in the gut–liver axis, defending the liver against colitis-induced injury. When LSECs are damaged, they can turn into a pro-inflammatory pattern under the stimulation of LPS. LSEC injury and colitis-derived LPS synergistically contribute to the recruitment and activation of hepatic neutrophils. Neutrophils play a pivotal role as a downstream effector in colitis-induced liver injury.

MicroRNA-9-5p protects liver sinusoidal endothelial cell against oxygen glucose deprivation/reperfusion injury.

BackgroundMaintenance of the function and survival of liver sinusoidal endothelial cells (LSECs) play a crucial role in hepatic ischemia/reperfusion (I/R) injury, a major cause of liver impairment during the surgical treatment. Emerging evidence indicates a critical role of microRNAs in I/R injury. This study aims to investigate whether miR-9-5p exerts a protective effect on LSECs.MethodsWe transfected LSECs with miR-9-5p mimic or mimic NC. LSECs were treated with oxygen and glucose deprivation (OGD, 5% CO2, and 95% N2), followed by glucose-free Dulbecco’s modified Eagle’s medium (DMEM) medium for 6 h and high glucose (HG, 30 mmol/L glucose) DMEM medium for 12 h. The biological role of miR-9-5p in I/R-induced LSEC injury was determined.ResultsIn the in vitro model of OGD/HG injury in LSECs, the expression levels of miR-9-5p were significantly downregulated, and those of CXC chemokine receptor-4 (CXCR4) upregulated. LSEC I/R injury led to deteriorated cell death, enhanced oxidative stress, and excessive inflammatory response. Mechanistically, we showed that miR-9-5p overexpression significantly downregulated both mRNA and protein levels of CXCR4, followed by the rescue of LSECs, ameliorated inflammatory response, and deactivation of pro-apoptotic signaling pathways.ConclusionsmiR-9-5p promotes LSEC survival and inhibits apoptosis and inflammatory response in LSECs following OGD/HG injury via downregulation of CXCR4.

Hypothermic oxygenated perfusion inhibits HECTD3-mediated TRAF3 polyubiquitination to alleviate DCD liver ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is an inevitable and serious clinical problem in donations after heart death (DCD) liver transplantation. Excessive sterile inflammation plays a fateful role in liver IRI. Hypothermic oxygenated perfusion (HOPE), as an emerging organ preservation technology, has a better preservation effect than cold storage (CS) for reducing liver IRI, in which regulating inflammation is one of the main mechanisms. HECTD3, a new E3 ubiquitin ligase, and TRAF3 have an essential role in inflammation. However, little is known about HECTD3 and TRAF3 in HOPE-regulated liver IRI. Here, we aimed to investigate the effects of HOPE on liver IRI in a DCD rat model and explore the roles of HECTD3 and TRAF3 in its pathogenesis. We found that HOPE significantly improved liver damage, including hepatocyte and liver sinusoidal endothelial cell injury, and reduced DCD liver inflammation. Mechanistically, both the DOC and HECT domains of HECTD3 directly interacted with TRAF3, and the catalytic Cys (C832) in the HECT domain promoted the K63-linked polyubiquitination of TRAF3 at Lys138. Further, the ubiquitinated TRAF3 at Lys138 increased oxidative stress and activated the NF-κB inflammation pathway to induce liver IRI in BRL-3A cells under hypoxia/reoxygenation conditions. Finally, we confirmed that the expression of HECTD3 and TRAF3 was obviously increased in human DCD liver transplantation specimens. Overall, these findings demonstrated that HOPE can protect against DCD liver transplantation-induced-liver IRI by reducing inflammation via HECTD3-mediated TRAF3 K63-linked polyubiquitination. Therefore, HOPE regulating the HECTD3/TRAF3 pathway is a novel target for improving IRI in DCD liver transplantation.

Functional Evaluations of Ex Vivo Induced Endothelial Progenitors for Autologous Transplantation in Non-Human Primates

It is possible to treat ischemia and hemophilia A diseases by producing sufficient functional human endothelial progenitor cells (EPCs)/endothelial cells (ECs) in vitro, for use with cell therapy in the clinic. We have previously reported the ability to produce FVIII-secreting EPCs/ ECs derived from human cord blood CD34+ cells. About 1412±102 fold expansion over initial EPCs was achieved after culturing for 21 days. An acute liver sinusoidal endothelial cells (LSEC) injury model in NOD/SCID mice was also developed to verify the functional migrating ability of the generated EPCs/ ECs in vivo.Here, we further applied this culturing technique to expand and subsequently differentiate CD34+ cells into the EPCs/ ECs derived from mobilized peripheral bloods of both human and cynomolgus monkeys. In brief, the CD34+ cells were isolated from human peripheral bloods or from monkeys (n=10) mobilized with human G-CSF/SCF. In the first 6 days, the isolated CD34+ cells were expanded in modified IMDM medium supplemented with human cytokine combinations of SCF, Flt-3L, TPO, IL-3, GM-CSF, and VEGF. From days 7 to 36, the adhering EPCs/ ECs were subsequently differentiated in EBM-2 basal medium with 20% FBS and endothelial growth factors of VEGF、IGF、EGF、FGF, and fibronectin. The purities and phenotypes of the induced EPCs/ECs were assessed in vitro by antibodies against human CD31, vWF, and FVIII for the human or Dil- acetylated- low density lipoprotein (ac-LDL) and FITC-lectin double staining for the monkey cells.In addition, the safety and efficacy of the induced monkey EPCs/ECs was determined in vivo by autologous transplantation in monkey LSEC injury model, which was induced by a toxic agent, monocrotaline (MCT), to disrupt the sinusoidal endothelial barrier and stimulate the incorporation of transplanted cells into liver parenchyma. In the transplantation group (n=7), each monkey was injected with double labeled autologous EPCs/ECs preparations (2×108 cells/500μl in saline), whereas in the control group (n=3) was injected with the same volume saline via hepatic portal vein injections. The cross-sections (20µm in depth) of fixed hepatic tissues were analyzed for grafting and functional migration of transplanted EPCs/ECs. The transplanted cells were identified by lenti-viral gene expressed with green fluorescent protein (red) or direct observation using anti-monkey IgG -microbead- FITC conjugates (green).For in vitro induced EPCs/ECs derived from human peripheral blood cell, the expansion of 834.58±119.03 fold was achieved from the CD34+/VEGFR2+ EPCs on day 21. Total more than 2x 108 FVIII-producing EPCs / ECs were produced from one collection of human peripheral blood (250 mL). On the other hand, the CD34+/VEGFR2+ EPCs (3.6×104 ±2.1×103) from one collection of monkey peripheral blood (20ml) were expanded up to 1274±166 fold and 7211±372 fold on days 24 and 36, respectively (n=4). The EPCs were reached at a logarithmic growth from days 12 to 45. The induced cells can be frozen and resuscitated during any stage of the culturing process. The formation of EC tubes was observed from day 24. Over 80% of expanded cells were EPC/EC-specific and identified by Dil-ac-LDL and FITC-lectin double staining on day 36. All monkeys recoveredfrom the surgeries of portal vein injection and resumed normal diet and behavior after autologous transplantation with cultured EPCs/ECs. Similarly, the routine blood analysis and liver functional enzymes were at the normal level, and no other apparent side effects were observed. About 3.2±1.4% and 2.1±1.1% of liver cells were observed as Dil-ac-LDL and FITC-lectin double positive in the liver cryosections (25 sections per monkey) on days 7 and 14, respectively, indicating that autologous transplanted EPCs/ECs were capable of repopulating into functional ECs in vivo. Furthermore, the injected EPCs/ECs were scattered in the intercellular spaces of hepatocytes at the hepatic tissues on day 14, suggesting that the transplanted cells could migrate towards injured LSEC sites and reconstitute structurally the sinusoidal endothelial compartment in monkey livers.In summary, the large-scale EPCs/ECs were produced from CD34+ cells of both human and monkey peripheral bloods in vitro. The safety and functions of the EPCs/ECs were confirmed in mice and cynomolgus monkeys, strongly suggesting the potential application of these FVIII-producing EPCs/ECs to future clinical study. DisclosuresQin:Biopharmagen. corp: Employment.

Pivotal role of liver sinusoidal endothelial cells in NAFLD/NASH progression

Liver sinusoidal endothelial cells (LSECs) are involved in the transport of nutrients, lipids, and lipoproteins, and LSEC injury occurs in various liver diseases including nonalcoholic fatty liver disease (NAFLD). However, the association between LSEC injury and NAFLD progression remains elusive. Accordingly, in this study, we aimed to elucidate the precise role of LSEC in the pathophysiology of NAFLD using two different mouse models, namely the choline-deficient, L-amino acid-defined and high-fat diet models. Administration of these diets resulted in liver metabolic dysregulation mimicking human NAFLD, such as steatosis, ballooning, lobular inflammation, and fibrosis, as well as central obesity, insulin resistance, and hyperlipidemia. LSEC injury appeared during the simple steatosis phase, and preceded the appearance of activated Kupffer cells and hepatic stellate cells (HSCs). These results indicate that LSEC injury may have a ‘gatekeeper' role in the progression from simple steatosis to the early nonalcoholic steatohepatitis (NASH) stage, and LSEC injury may be necessary for the activation of Kupffer cells and HSCs, which in turn results in the development and perpetuation of chronic liver injuries. Taken together, our data provide new insights into the role of LSEC injury in NAFLD/NASH pathogenesis.

Infusion of endothelial progenitor cells ameliorates liver injury in mice after haematopoietic stem cell transplantation.

Injury to liver sinusoidal endothelial cells (LSECs) is thought to be the initial factor for Hepatic veno-occlusive disease, a severe complication after haematopoietic stem cell transplantation (HSCT). Endothelial progenitor cells (EPCs) have the capacity to differentiate into endothelial cells and play a critical role in vasculogenesis, tissue regeneration and repair. Whether EPCs infusion ameliorates LSECs injury remains unclear. The aim of this study was to evaluate the effects of EPCs on liver injury in mice after HSCT. Mice received HSCT without or with EPCs infusion (HSCT + EPCs). Untreated mice were used as control. Liver and whole blood were collected post HSCT and used for the analysis of pathology of liver sinusoidal endothelial cells (LSECs) and hepatocytes, liver ultrastructure, function, level of IL-6, TNF-α and platelet activation. Severe LSECs injury, hepatocyte damage, abnormal liver function was observed in HSCT group. In addition, increased P-selectin expression and secretion of IL-6, TNF-α was also found. However, all the above changes were alleviated in HSCT + EPCs at all the time points and normalized at the endpoint. Meanwhile, EPCs-induced repair of LSECs and hepatocytes was totally inhibited by the addition of anti-VE-cadherin antibody. EPCs infusion ameliorated the damage to LSECs and hepatocytes as well as reduced secretion of IL-6, TNF-α and inhibited platelet activation after HSCT, leading to improved liver function, suggesting EPCs might be a new therapeutic strategy in the prophylaxis of liver injury after HSCT.

Co-transplantation of Liver Sinusoidal Endothelial Cells Promotes Repopulation of Transplanted Hepatocytes Following Hepatic Irradiation

Preparative hepatic irradiation enhances engraftment of transplanted hepatocytes. In this study, we sought to investigate the effect of hepatic irradiation on liver sinusoidal endothelial cells (LSECs) and whether co-transplantation of LSECs with hepatocytes can promote the proliferation of transplanted hepatocytes. Male F344 rats received HIR (10, 25 and 50 Gy) using a 320 kVP Philips orthovoltage unit and were sacrificed at various time points from 0 to 1 week post-HIR. Liver tissues were analyzed by H&E, TUNEL apoptosis assay, and electron microscopy. In the transplantation studies, 5 x 105 DPPIV-positive LSEC’s and/or 5 x 105 DPPIV-positive hepatocytes isolated from C57Bl/6 mice were injected intrasplenically to anesthetized DPPIV-deficient mice twenty-four hours after partial liver irradiation using HIR (20 and 40 Gy). The recipient mice were then sacrificed 60 days post transplantation. There was a dose-dependent increase in the number of apoptotic LSECs, as early as 2 h post-HIR, which peaked at 6 h. Electron microscopy demonstrated significant LSEC dehiscence at 24 h. Co-transplantation of liver sinusoidal endothelial cells and hepatocytes resulted in a dose dependent repopulation of the transplanted cells in the irradiated lobes. Interestingly, transplanted hepatocyte colonies formed only next to newly repopulated LSECs and there were no isolated DPPIV positive hepatocyte colonies (>10 cells) in areas where there was no DPPIV positive liver sinusoidal endothelial proliferation. This data suggests a dose-dependent hepatic LSEC injury. Transplantation of LSECs not only replaced injured liver endothelial cells but also promoted repopulation of the newly transplanted hepatocytes. This is consistent with recent reports demonstrating that newly recruited liver sinusoidal endothelial cells played a crucial role in liver regeneration and restoration of liver mass following partial hepatectomy and toxic liver injury and provide a rationale for promoting LSEC recruitment from progenitor cells in the liver and bone marrow to ameliorate liver function after radiation injury.

Cultured mycelium Cordyceps sinensis protects liver sinusoidal endothelial cells in acute liver injured mice.

Cultured mycelium Cordyceps sinensis (CMCS) was widely used for a variety of diseases including liver injury, the current study aims to investigate the protective effects of CMCS on liver sinusoidal endothelial cells (LSECs) in acute injury liver and related action mechanisms. The mice were injected intraperitoneally with lipopolysaccharide (LPS) and d-galactosamine (D-GalN). 39 male BABL/c mice were randomly divided into four groups: normal control, model control, CMCS treatment and 1,10-phenanthroline treatment groups. The Serum liver function parameters including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were assayed with the commercial kit. The inflammation and scaffold structure in liver were stained with hematoxylin and eosin and silver staining respectively. The LSECs and sub-endothelial basement membrane were observed with the scanning and transmission electronic microscope. The protein expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in liver were analyzed with Western blotting. Expression of von Willebrand factor (vWF) was investigated with immunofluorescence staining. The lipid peroxidation indicators including antisuperoxideanion (ASAFR), hydroxyl free radical (·OH), superoxide dismutase (SOD), malondialdehyde and glutathione S-transferase (GST) were determined with kits, and matrix metalloproteinase-2 and 9 (MMP-2/9) activities in liver were analyzed with gelatin zymography and in situ fluorescent zymography respectively. The model mice had much higher serum levels of ALT and AST than the normal mice. Compared to that in the normal control, more severe liver inflammation and hepatocyte apoptosis, worse hepatic lipid peroxidation demonstrated by the increased ASAFR, ·OH and MDA, but decreased SOD and GST, increased MMP-2/9 activities and VCAM-1, ICAM-1 and vWF expressions, which revealed obvious LSEC injury and scaffold structure broken, were shown in the model control. Compared with the model group, CMCS and 1,10-phenanthroline significantly improved serum ALT/AST, attenuated hepatic inflammation and improved peroxidative injury in liver, decreased MMP-2/9 activities in liver tissue, improved integration of scaffold structure, and decreased protein expression of VCAM-1 and ICAM-1. CMCS could protect LSECs from injury and maintain the microvasculature integration in acute injured liver of mice induced by LPS/D-GalN. Its action mechanism was associated with the down-regulation of MMP-2/9 activities and inhibition of peroxidation in injured liver.

Kupffer cells potentiate liver sinusoidal endothelial cell injury in sepsis by ligating programmed cell death ligand-1

PD-1 and PD-L1 have been reported to provide peripheral tolerance by inhibiting TCR-mediated activation. We have reported that PD-L1-/- animals are protected from sepsis-induced mortality and immune suppression. Whereas studies indicate that LSECs normally express PD-L1, which is also thought to maintain local immune liver tolerance by ligating the receptor PD-1 on T lymphocytes, the role of PD-L1 in the septic liver remains unknown. Thus, we hypothesized initially that PD-L1 expression on LSECs protects them from sepsis-induced injury. We noted that the increased vascular permeability and pSTAT3 protein expression in whole liver from septic animals were attenuated in the absence of PD-L1. Isolated LSECs taken from septic animals, which exhibited increased cell death, declining cell numbers, reduced cellular proliferation, and VEGFR2 expression (an angiogenesis marker), also showed improved cell numbers, proliferation, and percent VEGFR2(+) levels in the absence of PD-L1. We also observed that sepsis induced an increase of liver F4/80(+)PD-1(+)-expressing KCs and increased PD-L1 expression on LSECs. Interestingly, PD-L1 expression levels on LSECs decreased when PD-1(+)-expressing KCs were depleted with clodronate liposomes. Contrary to our original hypothesis, we document here that increased interactions between PD-1(+) KCs and PD-L1(+) LSECs appear to lead to the decline of normal endothelial function-essential to sustain vascular integrity and prevent ALF. Importantly, we uncover an underappreciated pathological aspect of PD-1:PD-L1 ligation during inflammation that is independent of its normal, immune-suppressive activity.

Kupffer cells potentiate the risk for liver sinusoidal endothelial cell injury in sepsis through programmed cell death receptor‐1 ligation

Endothelial cell (EC) dysfunction contributes to multiple organ injury—the cause of fatality seen in critically ill patients. Studies suggest that liver sinusoidal ECs (LSECs) maintain immune tolerance by directly ligating programmed‐death receptor‐1 (PD‐1) on leukocytes by their cell surface expression of PD‐ligand‐1 (PD‐L1). Reports indicate that LSECs express PD‐L1, but its role in the septic liver remains unknown. Thus, we hypothesized that increased PD‐1+leukocyte &amp; PD‐L1+LSEC interactions in sepsis, would lead to greater EC injury. We initially noted that increased EC permeability from septic livers induced by cecal ligation and puncture (CLP) in wild‐type (WT) mice decreased in CLP PD‐L1−/− mice. Isolated LSECs (CD146+CD45− cells) had an increase of PD‐L1 in CLP WT mice. We also found that LSECs from CLP PD‐L1−/− mice exhibit less apoptosis compared to CLP WT mice. Septic LSECs had lower expression of angiogenic marker VEGF‐R2, less proliferation, &amp; a 2x‐fold decrease in number vs. Shams; all of which were rescued in CLP PD‐L1−/− mice. Finally, there was a rise in PD‐1+ Kupffer cells (KCs), which are needed for septic LSEC PD‐L1 expression. These data suggests that increased interactions between PD‐1+ KCs &amp; PD‐L1+ LSECs results in injury during sepsis, yet suppresses tolerance, angiogenesis &amp; proliferation—essential for normal EC function. Supported by: NIH—F31DK083873 (N.H.) &amp; NIH—R01GM053209 (A.A.)

Liver sinusoidal endothelial cell injury by neutrophils in rats with acute obstructive cholangitis.

The objective of this study is to elucidate the potential role of poly-morphonuclear neutrophils (PMN) in the development of such a sinusoidal endothelial cell (SEC) injury during early acute obstructive cholangitis (AOC) in rats. Twenty one Wistar rats were divided into three groups: the AOC group, the bile duct ligated group (BDL group), and the sham operation group (SO group). The common bile duct (CBD) of rats in AOC group was dually ligated and 0.2 ml of the E. Coli O(111) B(4) (5 X 10(9)cfu/ml) suspension was injected into the upper segment, in BDL group, only the CBD was ligated and in SO group, neither injection of E. Coli suspension nor CBD ligation was done, but the same operative procedure. Such group consisted of seven rats, all animals were killed 6h after the operation. Morphological changes of the liver were observed under light and electron microscope. Expression of intercellular adhesion molecule-1 (ICAM-1) mRNA in hepatic tissue was determined with reverse transcription polymerase chain reaction (RT-PCR). The serum levels of alanine aminotransferase (ALT) were determined with an autoanalyger and cytokine-induced neutrophil chemoattractant (CINC) was determined by enzyme-linked immunosorbent assay (ELISA). Neutrophils was accumulated in the hepatic sinusoids and sinusoidal endothelial cell injury existed in AOC group. In contrast, in rats of BDL group, all the features of SEC damage were greatly reduced. Expression of ICAM-1 mRNA in hepatic tissue in three groups were 7.54 +/- 0.82, 2.87 +/- 0.34, and 1.01 +/- 0.12, respectively. There were significant differences among three groups (P<0.05). The serum CINC levels in the three groups were 188 +/- 21 ng.L(-1), 94+/-11 ng.L(-1), and 57+/-8 ng.L(-1), respectively. There were also significant differences among the three groups (P<0.05). Activity of the serum ALT was 917 +/- 167 nkat.L(-1), 901 +/- 171 nkat.L(-1), and 908 +/- 164 nkat.L(-1), respectively, (P<0.05). Hepatic SEC injury occurs earlier than hepatic parenchymal cells during AOC. Recruitments of circulating neutrophils in the hepatic sinusoidal space might mediate the SEC injury, and ICAM-1 in the liver may modulate the PMN of accumulation.