Carbon tetrachloride-induced liver injury in mice is tissue factor dependent

Coagulation System Activation for Targeting of COVID-19: Insights into Anticoagulants, Vaccine-Loaded Nanoparticles, and Hypercoagulability in COVID-19 Vaccines

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, is currently developing into a rapidly disseminating and an overwhelming worldwide pandemic. In severe COVID-19 cases, hypercoagulability and inflammation are two crucial complications responsible for poor prognosis and mortality. In addition, coagulation system activation and inflammation overlap and produce life-threatening complications, including coagulopathy and cytokine storm, which are associated with overproduction of cytokines and activation of the immune system; they might be a lead cause of organ damage. However, patients with severe COVID-19 who received anticoagulant therapy had lower mortality, especially with elevated D-dimer or fibrin degradation products (FDP). In this regard, the discovery of natural products with anticoagulant potential may help mitigate the numerous side effects of the available synthetic drugs. This review sheds light on blood coagulation and its impact on the complication associated with COVID-19. Furthermore, the sources of natural anticoagulants, the role of nanoparticle formulation in this outbreak, and the prevalence of thrombosis with thrombocytopenia syndrome (TTS) after COVID-19 vaccines are also reviewed. These combined data provide many research ideas related to the possibility of using these anticoagulant agents as a treatment to relieve acute symptoms of COVID-19 infection.

Liver Zonation - Revisiting Old Questions With New Technologies

Despite the ever-increasing prevalence of non-alcoholic fatty liver disease (NAFLD), the etiology and pathogenesis remain poorly understood. This is due, in part, to the liver's complex physiology and architecture. The liver maintains glucose and lipid homeostasis by coordinating numerous metabolic processes with great efficiency. This is made possible by the spatial compartmentalization of metabolic pathways a phenomenon known as liver zonation. Despite the importance of zonation to normal liver function, it is unresolved if and how perturbations to liver zonation can drive hepatic pathophysiology and NAFLD development. While hepatocyte heterogeneity has been identified over a century ago, its examination had been severely hindered due to technological limitations. Recent advances in single cell analysis and imaging technologies now permit further characterization of cells across the liver lobule. This review summarizes the advances in examining liver zonation and elucidating its regulatory role in liver physiology and pathology. Understanding the spatial organization of metabolism is vital to further our knowledge of liver disease and to provide targeted therapeutic avenues.

Antisense Tissue Factor Oligodeoxynucleotides Protected Diethyl Nitrosamine/Carbon Tetrachloride-Induced Liver Fibrosis Through Toll Like Receptor4-Tissue Factor-Protease Activated Receptor1 Pathway

Tissue factor (TF) is a blood coagulation factor that has several roles in many non-coagulant pathways involved in different pathological conditions such as angiogenesis, inflammation and fibrogenesis. Coagulation and inflammation are crosslinked with liver fibrosis where protease-activated receptor1 (PAR1) and toll-like receptor4 (TLR4) play a key role. Antisense oligodeoxynucleotides are strong modulators of gene expression. In the present study, antisense TF oligodeoxynucleotides (TFAS) was evaluated in treating liver fibrosis via suppression of TF gene expression. Liver fibrosis was induced in rats by a single administration of N-diethyl nitrosamine (DEN, 200 mg/kg; i. p.) followed by carbon tetrachloride (CCl4, 3 ml/kg; s. c.) once weekly for 6 weeks. Following fibrosis induction, liver TF expression was significantly upregulated along with liver enzymes activities and liver histopathological deterioration. Alpha smooth muscle actin (α-SMA) and transforming growth factor-1beta (TGF-1β) expression, tumor necrosis factor-alpha (TNF-α) and hydroxyproline content and collagen deposition were significantly elevated in the liver. Blocking of TF expression by TFAS injection (2.8 mg/kg; s. c.) once weekly for 6 weeks significantly restored liver enzymes activities and improved histopathological features along with decreasing the elevated α-SMA, TGF-1β, TNF-α, hydroxyproline and collagen. Moreover, TFAS decreased the expression of both PAR1 and TLR4 that were induced by liver fibrosis. In conclusion, we reported that blockage of TF expression by TFAS improved inflammatory and fibrotic changes associated with CCl4+DEN intoxication. In addition, we explored the potential crosslink between the TF, PAR1 and TLR4 in liver fibrogenesis. These findings offer a platform on which recovery from liver fibrosis could be mediated through targeting TF expression.

The Cytochrome P450-Mediated Metabolism Alternation of Four Effective Lignans From Schisandra chinensis in Carbon Tetrachloride-Intoxicated Rats and Patients With Advanced Hepatocellular Carcinoma

It is highly valuable to study the pharmacokinetics of herbal components under the pathological condition of liver dysfunction for safe and rational use of herbal medicines. In this study, the pharmacokinetic profiles of four effective lignans from Schisandra chinensis (SC), schisandrin, schisantherin A, deoxyshisandrin and γ-schisandrin, were investigated in carbon tetrachloride (CCl₄)-intoxicated rats. The metabolism of the four lignans was also studied using microsomes from patients with advanced hepatocellular carcinoma. In situ intestinal and hepatic perfusions were conducted to clarify the contributions from impairments of gut and liver on the pharmacokinetics of the four schisandra lignans in CCl₄-intoxicated rats. The metabolism in rat and human liver microsomes and transport in Caco-2 monolayer cell model were studied to reveal the key factors for the in vivo disposition of the four lignans. When SC alcoholic extract was orally administrated to CCl₄-intoxicated rat for a short term (4 days), the pharmacokinetics of four active SC lignans was significantly changed while its hepatotherapeutic effect was not obviously observed. The plasma concentrations of the four schisandra lignans were dramatically elevated compared with the control. The Cmax, AUC and MRT were all increased or prolonged significantly while parameter CLz/F was obviously reduced in rat pretreated with CCl₄. In hepatic perfusion study and liver microsomes incubation, it was found that the hepatic metabolism of the four lignans was markedly decreased mainly due to the activity reduction of multiple CYP450 isoenzymes involved the metabolism, which, eventually, might lead to the alternation of their pharmacokinetic profiles in CCl₄-intoxicated rats or patients with advanced hepatocellular carcinoma. The pharmacokinetic studies of SC components in pathological situation of liver dysfunction are expected to provide useful data for rational and safe application of SC preparations in clinic or further pharmacological and toxicological research.

Licochalcone E protects against carbon tetrachloride‑induced liver toxicity by activating peroxisome proliferator-activated receptor gamma

The present study aimed to investigate the hepatoprotective role of Licochalcone E (LCE) and its mechanism of action in a mouse model of carbon tetrachloride (CCl₄)-induced liver toxicity. Hepatotoxicity was induced in Kunming mice via an intraperitoneal injection (IP) of CCl₄, 10 ml/kg body weight, diluted with corn oil at a 1:500 ratio. LCE was administered once a day for 7 days (IP) as pretreatment at a dose of 5 mg/kg/day. The levels of C-reactive protein (CRP) and tumor necrosis factor (TNF)-α were analyzed to determine the inflammation status. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed using ELISA assays. Liver ultrastructure was observed via optical microscopy. The mRNA and protein expression levels of peroxisome proliferator-activated receptor (PPAR)γ, and nuclear factor (NF)-κB were assayed using quantitative polymerase chain reaction and western blot analysis, respectively. Pretreatment with LCE decreased levels of ALT, AST, CRP and TNF-α, and NF-κB expression in the experimental hepatotoxicity mice model induced by CCl₄. In addition, LCE increased the expression of PPARγ and normalized the hepatic histoarchitecture. However, the effects of LCE were reversed by cotreatment with the PPARγ inhibitor GW9662. The present study suggests that LCE may be used for the treatment of hepatotoxicity, and primarily exhibits its protective role through a PPARγ/NF-κB-mediated pathway.

Cytoplasmic domain of tissue factor promotes liver fibrosis in mice

AIM

To evaluate the role of tissue factor (TF) and protease activated receptor (PAR)-2 in liver fibrosis.

METHODS

Using CCl₄ administration for eight weeks, we induced hepatic fibrosis in wild-type C57BL/6 mice and in mice with deletion of the cytoplasmic signalling domain of TF (TF^§CT/§CT), deletion of PAR-2 (PAR-2^-/-) and combined deletion of TF signalling domain and PAR-2 (TF^§CT/§CT/PAR-2^-/-). Hepatic fibrosis area was assessed by quantitative imaging of picrosirius red staining. Hepatic collagen content was assessed by hydroxyproline levels. Hepatic stellate cells (αSMA positive) and hepatic macrophages (CD68 positive) were identified by immunohistochemistry. Hepatic gene expression was determined by PCR and liver TGFβ1 content by ELISA.

RESULTS

CCl₄ treated mice with deletion of the PAR-2 gene (PAR-2^-/-) and the cytoplasmic domain of TF (TF^§CT/§CT) developed significantly less hepatic fibrosis, characterised by reduced liver fibrosis area and hydroxyproline content, compared to control wildtype mice treated with CCl₄. The observed reduction in histological fibrosis was accompanied by a significant decrease in the hepatic content of TGFβ, the prototypic fibrogenic cytokine, as well as fewer activated hepatic stellate cells and hepatic macrophages. Deletion of the TF cytoplasmic signalling domain reduced hepatic fibrosis to levels similar to those observed in mice lacking PAR-2 signalling but combined deletion provided no added protection against fibrosis indicating a lack of mutual modulating effects that have been observed in other contexts such as angiogenic responses.

CONCLUSION

Tissue factor cytoplasmic domain is involved in TF-PAR-2 signalling initiating hepatic fibrosis and is a potential therapeutic target, as its deletion would not impact coagulation.

Pharmacokinetics in Vitro and in Vivo of Two Novel Prodrugs of Oleanolic Acid in Rats and Its Hepatoprotective Effects against Liver Injury Induced by CCl4

Oleanolic acid (OA) is a well-known pentacyclic triterpenoid compound, which has been used as a dietary supplement and is supplied as an over-the-counter drug for the treatment of human liver diseases. These are reasons for the low bioavailability of OA which have restricted its wider application. In this study, two OA prodrugs (1,3-cyclic propanyl phosphate esters of OA) were designed and synthesized. The hepatoprotective effects of these prodrugs were evaluated against carbon tetrachloride (CCl4) induced liver injury in mice; the levels of alanine aminotransferase (ALT), lactic dehydrogenase (LDH), and aspartate aminotransferase (AST) were significantly increased, and the level of the hepatic malondialdehyde (MDA) was increased. The metabolism, in vitro, of the prodrugs was studied by incubation in rat liver microsome; the plasma pharmacokinetics and the biodistribution in vivo after intravenous (iv) injection to six rats were investigated, respectively. The prodrugs diminished gradually with time; most of the parent drugs were released within 30 min in vitro, and the presumed mechanism of the in vitro metabolism was confirmed. The plasma-concentration data in vivo was analyzed by a compartmental method: both the prodrugs and the corresponding released parent drugs existed at up to 48 h in rats. The t1/2 improved after intravenous administration in rats compared with direct injection of the parent drugs. All analyte concentrations were highest in the liver, and most of the prodrugs were excreted in feces (>47.11%). Therefore, 1,3-cyclic propanyl phosphate esters of OA can serve as a promising lead candidate for drugs.