Fas-induced apoptosis increases hepatocyte tissue factor procoagulant activity in vitro and in vivo

Phosphatidylserine induce thrombotic tendency and liver damage in obstructive jaundice

INTRODUCTION

Hypercoagulability contributes to the majority of deaths and organ failure associated with obstructive jaundice (OJ). However, the exact mechanism of the coagulopathy in OJ remains elusive. Our objectives were to demonstrate whether phosphatidylserine (PS) exposure on blood cells (BCs), microparticles (MPs), and endothelial cells (ECs) can account for the hypercoagulability and liver damage in OJ patients.

METHODS

We evaluated OJ patients at two time point, which before (Day 0) and 7 days (Day 7) after the endoscopic retrograde cholangiopancreatography procedure (ERCP), and compared with healthy controls. Lactadherin was used to quantify PS exposure on BCs, MPs and ECs. Human umbilical vein endothelial cells (HUVECs) were incubated with serum of OJ patients and the expression of PS were evaluated. Meanwhile, healthy BCs and HUVECs were treated with 0, 25, 50 or 100µM unconjugated bilirubin (UCB) and PS exposure on cells were evaluated. Procoagulant activity was evaluated by purified coagulation complex assays, clotting time, and fibrin turbidity. In addition, we established a cholestatic mouse model by bile duct ligation to determine the potential role of PS in intrahepatic coagulation and liver damage.

RESULTS

Using flow cytometry, we found that OJ patients exhibited elevated levels of PS + BCs and associated MPs compared to the controls. Furthermore, the number of PS + BCs and MPs in patients at Day 0 were significantly higher than in patients at Day 7. Similarly, we observed markedly elevated PS exposure on HUVECs cultured with serum from patients at Day 0 versus serum from patients at Day 7. In vitro assays, PS exposure on BCs and HUVECs progressively increased with the concentration of UCB. Moreover, PS + BCs and MPs contributed to greatly shortened coagulation time and markedly enhanced coagulation factor Xa, thrombin, and fibrin generation. This procoagulant activity could be blocked approximately 80%, by the addition of lactadherin. Moreover, cholestatic mice exhibited significantly increased levels of liver tissue necrosis, fibrin deposition, and thrombophilia compared to sham mice. The enhanced intrahepatic coagulation and liver injury could be reversed by inhibiting PS with lactadherin.

CONCLUSIONS

These results highlight the pathogenic activity of PS + cells and MPs in promoting a prothrombotic environment and liver damage in OJ. As such, lactadherin, a PS blockade, may be a viable therapeutic strategy for treating such patients.

Hepatocyte-derived Microparticles as Novel Biomarkers for the Diagnosis of Deep Venous Thrombosis in Trauma Patients

Venous thromboembolism is a common complication following trauma. We investigated the dynamics of plasma microparticles (MPs) levels and explored their potential as biomarkers of deep vein thromboembolism (DVT) after trauma. A total of 775 patients with traumatic fractures were recruited in this nested study. About 106 trauma patients (53 DVT subjects and 53 age-, sex-, and fracture site-matched non-DVT subjects) and 53 healthy volunteers met the enrollment criteria. MPs were characterized by transmission electron microscope, nanoparticle tracking analysis, and western blotting. Circulating levels of MPs were measured using a flow cytometer. Meanwhile, routine laboratory parameters were examined in all patients. Compared to non-DVT patients, DVT patients had higher circulating phosphatidylserine (PS) + MPs, hepatocyte-derived MPs (HMPs), PS + HMPs, and platelet-derived MPs (PMPs). Notably, PS + HMPs had the best predictive value for DVT diagnosis in trauma patients (area under the curve [AUC] 0.8939, 95% CI 0.8326 to 0.9552), which was superior to d-dimer (AUC 0.5881). The Hepatic Procoagulant Index combined plasma levels of PS + HMPs and albumin, increasing the AUC to 0.8978 (95% CI 0.8396 to 0.9561). This is the first study that addressed circulating PS + HMPs are promising biomarkers with high performance in diagnosing DVT. The Hepatic Procoagulant Index is a potential predictor of DVT in trauma patients.

Hemostasis and Liver Regeneration

The liver is unique in its remarkable regenerative capacity, which enables the use of liver resection as a treatment for specific liver diseases, including removal of neoplastic liver disease. After resection, the remaining liver tissue (i.e, liver remnant) regenerates to maintain normal hepatic function. In experimental settings as well as patients, removal of up to two-thirds of the liver mass stimulates a rapid and highly coordinated process resulting in the regeneration of the remaining liver. Mechanisms controlling the initiation and termination of regeneration continue to be discovered, and many of the fundamental signaling pathways controlling the proliferation of liver parenchymal cells (i.e., hepatocytes) have been uncovered. Interestingly, while hemostatic complications (i.e., bleeding and thrombosis) are primarily thought of as a complication of surgery itself, strong evidence suggests that components of the hemostatic system are, in fact, powerful drivers of liver regeneration. This review focuses on the clinical and translational evidence supporting a link between the hemostatic system and liver regeneration, and the mechanisms whereby the hemostatic system directs liver regeneration discovered using experimental settings.

Circulating biomarkers of cell death

Numerous disease states are associated with cell death. For many decades, apoptosis and accidental necrosis have been assumed to be the two ways how a cell can die. The recent discovery of additional cell death processes such as necroptosis, ferroptosis or pyroptosis revealed a complex interplay between cell death mechanisms and diseases. Depending on the particular cell death pathway, cells secrete distinct molecular patterns, which differ between cell death types. This review focusses on released molecules, detectable in the blood flow, and their potential role as circulating biomarkers of cell death. We elucidate the molecular background of different biomarkers and give an overview on their correlation with disease stage, therapy response and prognosis in patients.

The role of microvesicles and its active molecules in regulating cellular biology

Cell‐derived microvesicles are membrane vesicles produced by the outward budding of the plasma membrane and released by almost all types of cells. These have been considered as another mechanism of intercellular communication, because they carry active molecules, such as proteins, lipids and nucleic acids. Furthermore, these are present in circulating fluids, such as blood and urine, and are closely correlated to the progression of pathophysiological conditions in many diseases. Recent studies have revealed that microvesicles have a dual effect of damage and protection of receptor cells. However, the nature of the active molecules involved in this effect remains unclear. The present study mainly emphasized the mechanism of microvesicles and the active molecules mediating the different biological effects of receptor cells by affecting autophagy, apoptosis and inflammation pathways. The effective ways of blocking microvesicles and its active molecules in mediating cell damage when microvesicles exert harmful effects were also discussed.

Direct Amplification of Tissue Factor:Factor VIIa Procoagulant Activity by Bile Acids Drives Intrahepatic Coagulation

OBJECTIVE

Regulation of TF (tissue factor):FVIIa (coagulation factor VIIa) complex procoagulant activity is especially critical in tissues where plasma can contact TF-expressing cells. One example is the liver, where hepatocytes are routinely exposed to plasma because of the fenestrated sinusoidal endothelium. Although liver-associated TF contributes to coagulation, the mechanisms controlling the TF:FVIIa complex activity in this tissue are not known. Approach and Results: Common bile duct ligation in mice triggered rapid hepatocyte TF-dependent intrahepatic coagulation coincident with increased plasma bile acids, which occurred at a time before observable liver damage. Similarly, plasma TAT (thrombin-antithrombin) levels increased in cholestatic patients without concurrent hepatocellular injury. Pathologically relevant concentrations of the bile acid glycochenodeoxycholic acid rapidly increased hepatocyte TF-dependent procoagulant activity in vitro, independent of de novo TF synthesis and necrotic or apoptotic cell death. Glycochenodeoxycholic acid increased hepatocyte TF activity even in the presence of the phosphatidylserine-blocking protein lactadherin. Interestingly, glycochenodeoxycholic acid and taurochenodeoxycholic acid increased the procoagulant activity of the TF:FVIIa complex relipidated in unilamellar phosphatidylcholine vesicles, which was linked to an apparent decrease in the K_m for FX (coagulation factor X). Notably, the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, a bile acid structural analog, did not increase relipidated TF:FVIIa activity. Bile acids directly enhanced factor X activation by recombinant soluble TF:FVIIa complex but had no effect on FVIIa alone.

CONCLUSIONS

The results indicate that bile acids directly accelerate TF:FVIIa-driven coagulation reactions, suggesting a novel mechanism whereby elevation in a physiological mediator can directly increase TF:FVIIa procoagulant activity.

Caspase Inhibition Reduces Hepatic Tissue Factor-Driven Coagulation In Vitro and In Vivo

Tissue factor (TF) is the primary activator of the blood coagulation cascade. Liver parenchymal cells (ie, hepatocytes) express TF in a molecular state that lacks procoagulant activity. Hepatocyte apoptosis is an important feature of acute and chronic liver diseases, and Fas-induced apoptosis increases hepatocyte TF procoagulant activity in vitro. We determined the impact of a pan-caspase inhibitor, IDN-7314, on hepatocyte TF activity in vitro and TF-mediated coagulation in vivo. Treatment of primary mouse hepatocytes with the Fas death receptor ligand (Jo2, 0.5 μg/ml) for 8 h increased hepatocyte TF procoagulant activity and caused release of TF-positive microvesicles. Pretreatment with 100 nM IDN-7314 abolished Jo2-induced caspase-3/7 activity and significantly reduced hepatocyte TF procoagulant activity and release of TF-positive microvesicles. Treatment of wild-type C57BL/6 mice with a sublethal dose of Jo2 (0.35 mg/kg) for 4.5 h increased coagulation, measured by a significant increase in plasma thrombin-antithrombin and TF-positive microvesicles. Total plasma microvesicle-associated TF activity was reduced in mice lacking hepatocyte TF; suggesting TF-positive microvesicles are released from the apoptotic liver. Fibrin(ogen) deposition increased in livers of Jo2-treated wild-type mice and colocalized primarily with cleaved caspase-3-positive hepatocytes. Pretreatment with IDN-7314 reduced caspase-3 activation, prevented the procoagulant changes in Jo2-treated mice, and reduced hepatocellular injury. Overall, the results indicate a central role for caspase activity in TF-mediated activation of coagulation following apoptotic liver injury. Moreover, the results suggest that liver-selective caspase inhibition may be a putative strategy to limit procoagulant and prothrombotic changes in patients with chronic liver disease.

Intrahepatic fibrin(ogen) deposition drives liver regeneration after partial hepatectomy in mice and humans

Platelets play a pivotal role in stimulating liver regeneration after partial hepatectomy in rodents and humans. Liver regeneration in rodents is delayed when platelets are inhibited. However, the exact mechanisms whereby platelets accumulate and promote liver regeneration remain uncertain. Thrombin-dependent intrahepatic fibrin(ogen) deposition was recently reported after partial hepatectomy (PHx) in mice, but the role of fibrin(ogen) deposits in liver regeneration has not been investigated. We tested the hypothesis that fibrin(ogen) contributes to liver regeneration by promoting intrahepatic platelet accumulation and identified the trigger of rapid intrahepatic coagulation after PHx. PHx in wild-type mice triggered rapid intrahepatic coagulation, evidenced by intrahepatic fibrin(ogen) deposition. Intrahepatic fibrin(ogen) deposition was abolished in mice with liver-specific tissue factor deficiency, pinpointing the trigger of coagulation after PHx. Direct thrombin activation of platelets through protease-activated receptor-4 did not contribute to hepatocyte proliferation after PHx, indicating that thrombin contributes to liver regeneration primarily by driving intrahepatic fibrin(ogen) deposition. Fibrinogen depletion with ancrod reduced both intrahepatic platelet accumulation and hepatocyte proliferation after PHx, indicating that fibrin(ogen) contributes to liver regeneration after PHx by promoting intrahepatic platelet accumulation. Consistent with the protective function of fibrin(ogen) in mice, low postoperative plasma fibrinogen levels were associated with liver dysfunction and mortality in patients undergoing liver resection. Moreover, increased intrahepatic fibrin(ogen) deposition was evident in livers of patients after liver resection but was remarkably absent in patients displaying hepatic dysfunction postresection. The results suggest a novel mechanism whereby coagulation-dependent intrahepatic fibrin(ogen) deposition drives platelet accumulation and liver regeneration after PHx.

Chitinase 3-like-1 promotes intrahepatic activation of coagulation through induction of tissue factor in mice

Coagulation is a critical component in the progression of liver disease. Identification of key molecules involved in the intrahepatic activation of coagulation (IAOC) will be instrumental in the development of effective therapies against liver disease. Using a mouse model of concanavalin A (ConA)-induced hepatitis, in which IAOC plays an essential role in causing liver injury, we uncovered a procoagulant function of chitinase 3-like 1 (Chi3l1). Chi3l1 expression is dramatically elevated after ConA challenge, which is dependent on ConA-induced T cell activation and the resulting interferon γ and tumor necrosis factor α productions. Compared with wild-type mice, Chi3l1-/- mice show less IAOC, reduced tissue factor (TF) expression, and attenuated liver injury. Reconstituting Chi3l1-/- mice with recombinant TF triggers IAOC and augments liver injury.

CONCLUSION

Our data demonstrate that Chi3l1, through induction of TF via mitogen-activated protein kinase activation, promotes IAOC and tissue injury. (Hepatology 2018;67:2384-2396).

Cylindrospermopsin toxicity in mice following a 90-d oral exposure

Cylindrospermopsin (CYN) is a toxin associated with numerous species of freshwater cyanobacteria throughout the world. It is postulated to have caused an episode of serious illnesses in Australia through treated drinking water, as well as lethal effects in livestock exposed to water from farm ponds. Toxicity included effects indicative of both hepatic and renal dysfunction. In humans, symptoms progressed from initial hepatomegaly, vomiting, and malaise to acidosis and hypokalemia, bloody diarrhea, and hyperemia in mucous membranes. Laboratory animal studies predominantly involved the intraperitoneal (i.p.) route of administration and confirmed this pattern of toxicity with changes in liver enzyme activities and histopathology consistent with hepatic injury and adverse renal effects. The aim of this study was designed to assess subchronic oral exposure (90 d) of purified CYN from 75 to 300 µg/kg/d in mouse. At the end of the dosing period, examinations of animals noted (1) elevated organ to body weight ratios of liver and kidney at all dose levels, (2) treatment-related increases in serum alanine aminotransferase (ALT) activity, (3) decreased blood urea nitrogen (BUN) and cholesterol concentrations in males, and (4) elevated monocyte counts in both genders. Histopathological alterations included hepatocellular hypertrophy and cord disruption in the liver, as well as renal cellular hypertrophy, tubule dilation, and cortical tubule lesions that were more prominent in males. A series of genes were differentially expressed including Bax (apoptosis), Rpl6 (tissue regeneration), Fabp4 (fatty acid metabolism), and Proc (blood coagulation). Males were more sensitive to many renal end points suggestive of toxicity. At the end of exposure, toxicity was noted at all dose levels, and the 75 µg/kg group exhibited significant effects in liver and kidney/body weight ratios, reduced BUN, increased serum monocytes, and multiple signs of histopathology indicating that a no-observed-adverse-effect level could not be determined for any dose level.

Inhibitory effect of Patrinia on BRL-3A cell apoptosis through the TLR4/PI3K/AKT/GSK3β and TLR4/P38/JNK signaling pathways

The present study investigated the inhibitory effect of Patrinia on lipopolysaccharide (LPS)-induced apoptosis of rat liver BRL‑3A cells. A Cell Counting Kit‑8 assay was performed to measure the effect of Patrinia on BLR‑3A cell activities. A biochemical assay was employed to detect the release of lactate dehydrogenase (LDH) in BRL‑3A cells induced by different doses of LPS. Based on the release rate of LDH, drug concentrations were set at 0.5, 1 and 2 g/l. Apoptotic morphology of cells was observed via Hoechst 33342 staining and flow cytometry was performed to detect apoptosis rates. Western blotting was performed to detect the expression of toll‑like receptor 4 (TLR4), protein kinase B (AKT), phosphorylated (P)‑AKTSer473, glycogen synthase kinase 3β (GSK3β), P‑GSK3βSer9, P38, P‑P38, c‑Jun N‑terminal kinase (JNK), P‑JNK, B‑cell lymphoma‑2 (Bcl‑2), Bcl‑2 associated X protein (Bax) and active‑caspase‑3 proteins. The translocation of GSK3β was observed by immunofluorescence staining. Results revealed that Patrinia increases cell activities and inhibits apoptosis. The expression levels of TLR4, P‑P38 and P‑JNK were reduced, whereas the expression of P‑AKTSer473 and P‑GSK3βSer9 were increased. Patrinia significantly reduced GSK3β nuclear translocation induced by LPS, and significantly decreased the mRNA expression levels of Bax/Bcl‑2 and caspase‑3 in BRL‑3A cells induced by LPS. In conclusion, Patrinia may significantly reduce apoptosis of BRL‑3A induced by LPS via the TLR4/PI3K/AKT/GSK3β and TLR4/P38/JNK signaling pathways, providing evidence for its potential use in liver disease therapy.

Role of Fibrin(ogen) in Progression of Liver Disease: Guilt by Association?

Strong experimental evidence indicates that components of the hemostatic system, including thrombin, exacerbate diverse features of experimental liver disease. Clinical studies have also begun to address this connection and some studies have suggested that anticoagulants can improve outcome in patients with liver disease. Among the evidence of coagulation cascade activation in models of liver injury and disease is the frequent observation of thrombin-driven hepatic fibrin(ogen) deposition. Indeed, hepatic fibrin(ogen) deposition has long been recognized as a consequence of hepatic injury. Although commonly inferred as pathologic due to protective effects of anticoagulants in mouse models, the role of fibrin(ogen) in acute liver injury and chronic liver disease may not be universally detrimental. The localization of hepatic fibrin(ogen) deposits within the liver is connected to the disease stimulus and in animal models of liver toxicity and chronic disease, fibrin(ogen) deposition may not always be synonymous with large vessel thrombosis. Here, we provide a balanced review of the experimental evidence supporting a direct connection between fibrin(ogen) and liver injury/disease pathogenesis, and suggest a path forward bridging experimental and clinical research to improve our knowledge on the nature and function of fibrin(ogen) in liver disease.

Endosulfan inducing blood hypercoagulability and endothelial cells apoptosis via the death receptor pathway in Wistar rats

Endosulfan induces blood hypercoagulability by causing vWF release from endothelial cell apoptosis in Wistar rats.