Classification and Epidemiologic Aspects of Acute Liver Failure

Coronary Microvascular Dysfunction in Acute Cholestasis-Induced Liver Injury

BACKGROUND

Previous studies have shown cardiac abnormalities in acute liver injury, suggesting a potential role in the associated high mortality.

METHODS

We designed an experimental study exploring the short-term effects of acute cholestasis-induced liver injury on cardiac function and structure in a rodent bile duct ligation (BDL) model to elucidate the potential interplay. Thirty-seven male Sprague-Dawley rats were subjected to BDL surgery (n = 28) or served as sham-operated (n = 9) controls. Transthoracic echocardiography, Doppler evaluation of the left anterior descending coronary artery, and myocardial contrast echocardiography were performed at rest and during adenosine and dobutamine stress 5 days after BDL. Immunohistochemical staining of myocardial tissue samples for hypoxia and inflammation as well as serum analysis were performed.

RESULTS

BDL animals exhibited acute liver injury with elevated transaminases, bilirubin, and total circulating bile acids (TBA) 5 days after BDL (TBA control: 0.81 ± 2.54 µmol/L vs. BDL: 127.52 ± 57.03 µmol/L; p < 0.001). Concurrently, cardiac function was significantly impaired, characterized by reduced cardiac output (CO) and global longitudinal strain (GLS) in the echocardiography at rest and under pharmacological stress (CO rest control: 120.6 ± 24.3 mL/min vs. BDL 102.5 ± 16.6 mL/min, p = 0.041; GLS rest control: -24.05 ± 3.8% vs. BDL: -18.5 ± 5.1%, p = 0.01). Myocardial perfusion analysis revealed a reduced myocardial blood flow at rest and a decreased coronary flow velocity reserve (CFVR) under dobutamine stress in the BDL animals (CFVR control: 2.1 ± 0.6 vs. BDL: 1.7 ± 0.5 p = 0.047). Immunofluorescence staining indicated myocardial hypoxia and increased neutrophil infiltration.

CONCLUSIONS

In summary, acute cholestasis-induced liver injury can lead to impaired cardiac function mediated by coronary microvascular dysfunction, suggesting that major adverse cardiac events may contribute to the mortality of acute liver failure. This may be due to endothelial dysfunction and direct bile acid signaling.

Nanobody-based pannexin1 channel inhibitors reduce inflammation in acute liver injury

BACKGROUND

The opening of pannexin1 channels is considered as a key event in inflammation. Pannexin1 channel-mediated release of adenosine triphosphate triggers inflammasome signaling and activation of immune cells. By doing so, pannexin1 channels play an important role in several inflammatory diseases. Although pannexin1 channel inhibition could represent a novel clinical strategy for treatment of inflammatory disorders, therapeutic pannexin1 channel targeting is impeded by the lack of specific, potent and/or in vivo-applicable inhibitors. The goal of this study is to generate nanobody-based inhibitors of pannexin1 channels.

RESULTS

Pannexin1-targeting nanobodies were developed as potential new pannexin1 channel inhibitors. We identified 3 cross-reactive nanobodies that showed affinity for both murine and human pannexin1 proteins. Flow cytometry experiments revealed binding capacities in the nanomolar range. Moreover, the pannexin1-targeting nanobodies were found to block pannexin1 channel-mediated release of adenosine triphosphate. The pannexin1-targeting nanobodies were also demonstrated to display anti-inflammatory effects in vitro through reduction of interleukin 1 beta amounts. This anti-inflammatory outcome was reproduced in vivo using a human-relevant mouse model of acute liver disease relying on acetaminophen overdosing. More specifically, the pannexin1-targeting nanobodies lowered serum levels of inflammatory cytokines and diminished liver damage. These effects were linked with alteration of the expression of several NLRP3 inflammasome components.

CONCLUSIONS

This study introduced for the first time specific, potent and in vivo-applicable nanobody-based inhibitors of pannexin1 channels. As demonstrated for the case of liver disease, the pannexin1-targeting nanobodies hold great promise as anti-inflammatory agents, yet this should be further tested for extrahepatic inflammatory disorders. Moreover, the pannexin1-targeting nanobodies represent novel tools for fundamental research regarding the role of pannexin1 channels in pathological and physiological processes.

Anti-inflammatory and antinociceptive effects, and safety toxicological profile of a new paracetamol analog, LQFM291

In the scope of a research program with the goal of developing treatments for inflammatory diseases, the pharmacological evaluation of LQFM291, designed by molecular hybridization from butylated hydroxytoluene and paracetamol, was described. The antioxidant profile of LQFM291 was evaluated by electrochemical measurement. Also, acute or repeated treatments with equimolar doses to paracetamol were used to evaluate the antinociceptive and/or anti-inflammatory activities of LQFM291 in animal models. The toxicologic potential of LQFM291 was also evaluated and compared to paracetamol through biochemical and histopathological analysis after the repeated treatment schedule. As a result of the acute treatment, paracetamol showed a similar antinociceptive effect in formalin test compared to LQFM291. Whereas, after the repeated treatment, when carrageenan-induced hyperalgesia and edema tests were performed, paracetamol showed a delayed antinociceptive and anti-inflammatory effect compared to LQFM291. Furthermore, as other advantages the LQFM291 showed a high redox capacity, a gastroprotective activity and a safety pharmacological profile without any liver or kidney damage. These effects can be related to the prevention of oxidative stress by reduction of protein and lipid peroxidation in gastric tissue, maintenance of glutathione levels in hepatic homogenate, and a systemic reduction of pro-inflammatory cytokine levels, which may characterize the LQFM291 as a more viable and effective alternative to relief pain and inflammatory signs in patients with chronic disorders.

Transjugular liver biopsy and hepatic venous pressure gradient measurement in patients with and without liver cirrhosis

BACKGROUND

Transjugular liver biopsy (TJLB) and hepatic venous pressure gradient (HVPG) measurement are diagnostic procedures for patients with acute and chronic liver diseases. Technical execution of TJLB and HVPG may be challenging in patients with advanced liver disease.

OBJECTIVE

We studied consecutive TJLB and HVPG procedures and investigated technical success, complications, quality of biopsies, indications and treatment changes in patients with and without liver cirrhosis.

METHODS

In the study period from 2010 to 2018, 575 consecutive TJLB and HVPG procedures were analyzed. Demographic characteristics, procedure-related and follow-up data were extracted from medical records.

RESULTS

In total, 259 (45%) patients were diagnosed with liver cirrhosis whereas 316 (55%) patients had no evidence of advanced chronic liver disease. Technical success of TJLB was significantly higher in patients without liver cirrhosis (287; 92%) compared to patients with liver cirrhosis [184; 76.7% (P = 0.001)]. Technical success of HVPG measurement was not different between both groups (P = 0.553). Liver biopsy specimens were significantly shorter in patients with liver cirrhosis (P = 0.001). Medical therapy was adjusted in 163 (28.4%) patients. In patients with liver cirrhosis, results of TJLB led less frequently to therapy initiation or adjustment compared to patients without liver cirrhosis (P = 0.001). In multivariate analysis, liver cirrhosis (Exp(B) 1.866; P = 0.012), alanine aminotransferase (Exp(B) 0.248; P < 0.001) and INR (Exp(B) 0.583; P = 0.027) were independently associated with treatment change.

CONCLUSION

Technical success and therapeutic decisions of TJLB are directly linked to presence or absence of liver cirrhosis.

Acute myocardial injury secondary to severe acute liver failure: A retrospective analysis supported by animal data

To investigate whether acute liver failure (ALF) leads to secondary acute myocardial injury, 100 ALF patients that were retrospectively identified in a single center based on ICD 10 codes and 8 rats from an experimental study that died early after bile duct ligation (BDL) were examined. Creatine kinase (CK), creatine kinase-MB isoenzyme (CKMB) and cardiac troponin-I (cTnI) were analyzed as markers of myocardial injury. For histological analysis, hematoxylin-eosin (HE), elastic Van Gieson (EVG), CD41 and myeloperoxidase were used to stain rat hearts. Major adverse cardiac events (MACEs) were a critical factor for mortality (p = 0.037) in human ALF. Deceased patients exhibited higher levels of CKMB than survivors (p = 0.023). CKMB was a predictor of mortality in ALF (p = 0.013). Animals that died early after BDL exhibited increased cTnI, CKMB, tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) levels compared to controls (cTnI: p = 0.011, CKMB: p = 0.008, TNFα: p = 0.003, IL-6: p = 0.006). These animals showed perivascular lesions and wavy fibers, microthrombi and neutrophilic infiltration in the heart. MACEs are decisive for mortality in human ALF, and elevated CKMB values indicate that this might be due to structural myocardial damage. Accordingly, CKMB was found to have predictive value for mortality in ALF. The results are substantiated by data from a rat BDL model demonstrating diffuse myocardial injury.

Acute (fulminant) liver failure: a clinical and imaging review

Acute liver failure (ALF) is a rare clinical entity with high morbidity and mortality frequently requiring liver transplantation for survival. Imaging, particularly with ultrasound, plays an important role, especially to distinguish patients with underlying chronic liver disease who have lower transplant priority. We discuss the clinical and imaging findings in the three subtypes of ALF using a multi-modality approach with an emphasis on ultrasound.

Silencing long noncoding RNA NEAT1 alleviates acute liver failure via the EZH2-mediated microRNA-139/PUMA axis

This study aimed to investigate the role of long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in the development of ALF. We collected blood samples from patients with acute liver failure (ALF) and established an ALF mouse model induced by D-galactosamine/Lipopolysaccharide (D-GalN/LPS) for in vivo studies. Peripheral blood mononuclear cells (PMBCs) induced with LPS were isolated for in vitro experiments. Survival tests, histological analysis, and biochemical indicator assays were conducted. Luciferase assay was performed to determine the binding affinity between microRNA-139 (miR-139) and p53-upregulated modulator of apoptosis (PUMA). Expression of lncRNA NEAT1, enhancer of zeste homolog 2 (EZH2), and PUMA was upregulated, while the expression of miR-139 was downregulated in clinical samples and D-GalN/LPS induced ALF mouse model. LncRNA NEAT1 promoted the enrichment of H3K27me3 on the promoter region of miR-139 via EZH2, which led to suppression of miR-139. The inhibition of miR-139 resulted in the upregulation of its downstream target PUMA. The NEAT1/miR-139/PUMA pathway upregulated the production of pro-inflammatory cytokines, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β, thereby mediating the progression of ALF. In conclusion, silencing lncRNA NEAT1 upregulated the expression of miR-139 through EZH2, leading to the downregulation of PUMA, which alleviated the development of ALF.

Panaxynol from Saposhnikovia diviaricata exhibits a hepatoprotective effect against lipopolysaccharide + D-Gal N induced acute liver injury by inhibiting Nf-κB/IκB-α and activating Nrf2/HO-1 signaling pathways

We investigated the mechanism of action of panaxynol (PAL) extract from the root of Saposhnikovia diviaricata (Turcz.) Schischk for treating acute liver injury caused by lipopolysaccharide (LPS) and D-galactosamine (D-Gal N) in mice. A mouse model of acute liver failure induced by LPS/D-Gal N was established. Mice were divided randomly into three equal groups: control group, LPS/D-Gal N group and PAL group. After seven days of continuous PAL administration, all animals except controls were injected with 50 μg/kg LPS and 800 mg/kg D-Gal N; blood and liver samples were collected after 8 h. Compared to the LPS/D-Gal N group, the levels of catalase, glutathione and superoxide dismutase were increased in the liver of the PAL group. The inflammatory response index indicated that PAL attenuated LPS/D Gal N-induced liver pathological injury and decreased levels of hepatic malondialdehyde, serum alanine aminotransferase, aspartate transaminase, tumor necrosis factor-α, and interleukins 1β and 6. PAL also inhibited LPS/D-Gal N induced nuclear factor-kappa B (Nf-κB), inhibitor kappa B-α (IκB-α) activation, and up-regulated Nrf2 and heme oxygenase-1 (HO-1) expression. PAL can prevent LPS/D-Gal N induced acute liver injury by activating Nrf2/HO-1 to stimulate antioxidant defense and inhibit the IkB-α/NF-κB signaling pathway.

Acute hepatitis and acute liver failure: Pathologic diagnosis and differential diagnosis

Acute hepatitis and acute liver failure are severe medical conditions that require early clinical intervention. Histopathologic findings on a liver biopsy or a liver explant may help identify the underlying etiology or provide an important direction for further clinical, laboratory and radiographical investigation. This review is divided into two main portions. The first portion concentrates on various etiologies and discusses unique histologic features that can be associated with specific etiologies. The second portion describes the general morphologic features based on which the diagnosis of acute hepatitis and acute liver failure are made. Histopathologic distinction between collapse and cirrhosis and limitations of histopathologic assessment for underlying etiologies are addressed in this portion. Another focus of this review is non-necrotic acute liver failure, which typically features diffuse microvesicular steatosis secondary to various etiologies causing mitochondrial dysfunction. Molecular testing serves an increasingly important role in the diagnosis and management of this group of disorders.