The novel cyclophilin inhibitor C105SR reduces hepatic ischaemia-reperfusion injury via mitoprotection

Background & Aims

Mitochondrial permeability transition pore (mPTP) opening is critical for mediating cell death during hepatic ischaemia-reperfusion injury (IRI). Blocking mPTP opening by inhibiting cyclophilin D (CypD) is a promising pharmacological approach for the treatment of IRI. Here, we show that diastereoisomers of a new class of small-molecule cyclophilin inhibitors (SMCypIs) have properties that make them attractive candidates for the development of therapeutic agents against liver IRI.

Methods

Derivatives of the parent SMCypI were synthesised and evaluated for their ability to inhibit CypD peptidyl-prolyl cis-trans isomerase (PPIase) activity and for their mitoprotective properties, evaluated by measuring mitochondrial swelling and calcium retention capacity in liver mitochondria. The ability of the selected compounds to inhibit mPTP opening was evaluated in cells subjected to hypoxia/reoxygenation using a calcein/cobalt assay. Their ability to inhibit cell death was evaluated in cells subjected to hypoxia/reoxygenation by measuring lactate dehydrogenase (LDH) release, propidium iodide staining, and cell viability. The compound performing best in vitro was selected for in vivo efficacy evaluation in a mouse model of hepatic IRI.

Results

The two compounds that showed the strongest inhibition of CypD PPIase activity and mPTP opening, C105 and C110, were selected. Their SR diastereoisomers carried the activity of the racemic mixture and exhibited mitoprotective properties superior to those of the known macrocyclic cyclophilin inhibitors cyclosporin A and alisporivir. C105SR was more potent than C110SR in inhibiting mPTP opening and prevented cell death in a model of hypoxia/reoxygenation. Finally, C105SR substantially protected against hepatic IRI in vivo by reducing hepatocyte necrosis and apoptosis.

Conclusions

We identified a novel cyclophilin inhibitor with strong mitoprotective properties both in vitro and in vivo that represents a promising candidate for cellular protection in hepatic IRI.

Impact and Implications

Hepatic ischaemia-reperfusion injury (IRI) is one of the main causes of morbidity and mortality during or after liver surgery. However, no effective therapies are available to prevent or treat this devastating syndrome. An attractive strategy to prevent hepatic IRI aims at reducing cell death by targeting mitochondrial permeability transition pore opening, a phenomenon regulated by cyclophilin D. Here, we identified a new small-molecule cyclophilin inhibitor, and demonstrated the enhanced mitoprotective and hepatoprotective properties of one of its diastereoisomers both in vitro and in vivo, making it an attractive lead compound for subsequent clinical development.

Hepatic damage caused by flaviviruses: A systematic review

Flaviviruses infect arthropods and mammals and their pathologies are a considerable global health problem, affecting about 400 million people per year. The symptoms of these flaviviruses range from mild manifestations such as nausea, vomiting, and headache to more serious cases such as hemorrhage, meningitis, microcephaly, kidney, and liver failure. This review aims to compile the morphological changes that occur due to infections caused by dengue, yellow fever, and Zika viruses, as well as to describe possible mechanisms of action of such flaviviruses in the liver. PRISMA guidelines were used to search for studies associating flavivirus with liver disorders. Two independent reviewers selected the studies on PubMed/Medline, Web of Science, and Scopus search platforms. The SYRCLE software was used for the evaluation of the study's quality. Eighteen experimental articles were included. The experimental animals often used in experiments were monkeys (5 %), hamsters (10 %), chicken embryos (10 %), and mice (75 %). It is evident that there is a strong hepatic interaction with flaviviruses, and the main hepatic alterations found were steatosis, apoptosis, necrosis, hemorrhage, elevation of ALT and AST levels, and total bilirubin. Flavivirus infection, in general, trigger an upregulation of pro-inflammatory cytokines, leading to structural changes in mitochondria that activate cascades of cellular death and promote insulin resistance. The majority of the studies primarily focus on dengue and yellow fever viruses, while the findings related to Zika virus exposure are still relatively limited and require further investigation.

Molecular mechanisms in thioacetamide-induced acute and chronic liver injury models

Thioacetamide (TAA) undergoes bioactivation in the liver by the CYP450 2E1 enzyme, resulting in the formation of TAA-S-oxide and TAA-S-dioxide. TAA-S-dioxide induces oxidative stress via lipid peroxidation of the hepatocellular membrane. A single TAA dose (50-300 mg/kg) administration initiates hepatocellular necrosis around the pericentral region after its covalent binding to macromolecules in the liver. Intermittent TAA administration (150-300 mg/kg, weekly thrice, for 11-16 weeks) activates transforming growth factor (TGF)-β/smad3 downstream signaling in injured hepatocytes, causing hepatic stellate cells (HSCs) to acquire myofibroblast like phenotype. The activated HSCs synthesize a variety of extracellular matrix, leading to liver fibrosis, cirrhosis, and portal hypertension. The TAA induced liver injury varies depending on the animal model, dosage, frequency, and routes of administration. However, TAA induces hepatotoxicity in a reproducible manner, and it is an ideal model to evaluate the antioxidant, cytoprotective, and antifibrotic compounds in experimental animals.

Liver abscess with necrosis in post COVID-19: A case report

INTRODUCTION

Coronavirus disease 2019 (COVID-19) is an acute respiratory tract infection caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2). Recent evidences mentioned the possibility of COVID-19 as a systemic infectious and inflammatory disease. Signs and symptoms of liver and gastrointestinal system are often found in post-acute COVID-19 patients. However, there are only few data found about liver abscess and necrosis in post COVID-19 patients.

CASE PRESENTATION

A 49-year-old man admitted to the hospital with dyspnea, nausea, loss of appetite and epigastric pain, post confirmed SARS CoV-2 severe pneumonia 1 month ago in ICU with noninvasive ventilator (NIV), enoxaparin, tocilizumab, azithromycin, levofloxacin, hydroxychloroquine, and no preexisting liver condition. Swab PCR result was negative. The result of abdominal computed tomography (CT) scan with contrast was liver abscess formation with hemorrhages measuring about 16 × 12 × 11 cm & 10 × 9x9 cm occupying most of the right lobe liver. The patient underwent exploratory laparotomy, there were multiple liver abscesses in segment 8 with parenchymal liver necrosis and abscesses in segment 7 of liver. Necrosectomy and liver abscess drainage was performed.

CLINICAL DISCUSSION

Pathophysiology of liver damage in post COVID-19 are direct cytotoxicity of SARS-CoV2, immune-mediated due to severe systemic inflammatory response syndrome (SIRS) in COVID-19, hypoxemia, vascular changes due to coagulopathy, endothelitis or congestion from right heart failure, and drug-induced liver injury (DILI).

CONCLUSION

The possible pathophysiology of liver abscess and necrosis in post COVID-19 should be considered in monitoring and management for both COVID-19 patients and post COVID-19 patients.

Neutrophil accumulation within tissues: A damage x healing dichotomy

The abundance of neutrophils in human circulation, their fast mobilization from blood to tissues, along with their alleged short life-span led to the image of neutrophils as a homogeneous cell type designed to fight infections and die in the process. Additionally, their granule content and capacity to produce molecules with considerable cytotoxic potential, lead to the general belief that neutrophil activation inexorably results in side effect of extensive tissue injury. Neutrophil activation in fact causes tissue injury as an adverse effect, but it seems that this is restricted to particular pathological situations and more of an "exception to the rule". Here we review evidences arising especially from intravital microscopy studies that demonstrate neutrophils as cells endowed with sophisticated mechanisms and able to engage in complex interactions as to minimize damage and optimize their effector functions. Moreover, neutrophil infiltration may even contribute to tissue healing and repair which may altogether demand a reexamination of current anti-inflammatory therapies that have neutrophil migration and activation as a target.

The Effect of Different Doses of Mesobuthus eupeus (Scorpionida: Buthidae) Scorpion Venom on the Production of Liver Necrosis in Nmri Mice

Background:

Scorpion venom has a variety of different components considerably. Some of these compounds are proteins such as Phospholipase A2 which is one of the most important. Use of scorpion venom for the treatment of any disease requires an initial study to determine the therapeutic dose or safe dose. Therefore, due to the necessity of studying scorpion venom, it is of special importance to study the effects of its dose response in animal tissues.

Methods:

To determine the inflammatory effects of scorpion’s venom (Mesobuthus eupeus), 50 Nmri mice with an average weight of 24±7g were selected for investigation in two experiments. In first-round 25 of them were divided into 5 groups and were exposed to different doses of venom injection paralleling the control group. Single-injection of various doses on 25 mice was performed and results were compared.

Results:

There was a significant differences between the test and control groups (in most groups). Liver necrosis was one of the important symptoms in this study, the severity of which was measured and statistically analyzed.

Conclusion:

It was determined that 0.05ppm is a safe dose and sub-lethal doses can use for the investigation of therapeutic effects of venom on cancer, diabetes, dermatitis, and so on.

Acute liver failure and HELLP syndrome: A clinical case and literature review

BACKGROUND

HELLP syndrome is a pregnancy-related liver disease associated with increased maternal and foetal mortality. In rare cases, it can lead to the development of a subcapsular hepatic haematoma as well as its rupture. This rupture is life-threatening if not urgently treated.

METHOD

We describe a clinical case of HELLP syndrome involving a ruptured subcapsular liver haematoma and contextualise this with a literature overview.

CLINICAL CASE

A 39-year-old woman of 40 weeks' gestation presented to her local Emergency Department with symptoms and serology classically associated with HELLP syndrome. However, she clinically deteriorated and developed a ruptured subcapsular haematoma. She underwent an emergency Caesarean section at her initial hospital. Upon clinical stabilisation, she was transferred to our transplant unit for an urgent liver transplant.

CONCLUSION

LT is a life-saving procedure for patients with acute liver failure secondary to HELLP syndrome. These patients should be immediately referred to a high-volume transplant centre.

The pyrrolizidine alkaloid senecionine induces CYP-dependent destruction of sinusoidal endothelial cells and cholestasis in mice

Pyrrolizidine alkaloids (PAs) are widely occurring phytotoxins which can induce severe liver damage in humans and other mammalian species by mechanisms that are not fully understood. Therefore, we investigated the development of PA hepatotoxicity in vivo, using an acutely toxic dose of the PA senecionine in mice, in combination with intravital two-photon microscopy, histology, clinical chemistry, and in vitro experiments with primary mouse hepatocytes and liver sinusoidal endothelial cells (LSECs). We observed pericentral LSEC necrosis together with elevated sinusoidal marker proteins in the serum of senecionine-treated mice and increased sinusoidal platelet aggregation in the damaged tissue regions. In vitro experiments showed no cytotoxicity to freshly isolated LSECs up to 500 µM senecionine. However, metabolic activation of senecionine by preincubation with primary mouse hepatocytes increased the cytotoxicity to cultivated LSECs with an EC50 of approximately 22 µM. The cytochrome P450 (CYP)-dependency of senecionine bioactivation was confirmed in CYP reductase-deficient mice where no PA-induced hepatotoxicity was observed. Therefore, toxic metabolites of senecionine are generated by hepatic CYPs, and may be partially released from hepatocytes leading to destruction of LSECs in the pericentral region of the liver lobules. Analysis of hepatic bile salt transport by intravital two-photon imaging revealed a delayed uptake of a fluorescent bile salt analogue from the hepatic sinusoids into hepatocytes and delayed elimination. This was accompanied by transcriptional deregulation of hepatic bile salt transporters like Abcb11 or Abcc1. In conclusion, senecionine destroys LSECs although the toxic metabolite is formed in a CYP-dependent manner in the adjacent pericentral hepatocytes.

Impairments of bone marrow hematopoietic cells followed by the sever erythrocyte damage and necrotic liver as the outcome of chronic in vivo exposure to cadmium: novel insights from quails

Cadmium is a heavy metal classified as an environmental hazard, and its toxicity is subject to extensive research. Japanese quails were exposed to cadmium chloride (CdCl₂) ad libitum for 20 days. Bone marrow, peripheral blood and liver were analyzed following the exposure. Moreover, we have provided the very first explanation of hematopoietic lines in Japanese quail. Following CdCl₂ exposure, changes in the number, size and morphology of blood cells were observed in both peripheral blood and bone marrow. Alterations included severe erythrocyte damage, monocytosis and lymphopenia. In the liver of Cd-exposed animals we observed necrotic cells, absence of hematopoietic regions and cytogenetic changes of hepatocytes. Alterations in the bone marrow were also noted, as well as giant phagocytic cells, most likely macrophages. In vivo, CdCl₂ exposure caused swift and destructive changes in the hematopoietic niche, liver and other tissues responsible for the detoxification cycle of cadmium and its compounds.

Differential Diagnosis of Hepatic Necrosis Encountered at Autopsy

The liver is subject to a variety of extrinsic and intrinsic insults that manifest with both specific and nonspecific patterns of necrosis. In the autopsy setting, these patterns are often encountered as incidental findings or even causes of death. There are several etiologies of hepatic necrosis, including toxins, drug injuries, viral infections, ischemic injuries, and metabolic disease, all of which possess overlapping gross and histologic presentations. Nonetheless, patterned necrosis in the context of clinical and demographic history allows for the forensic pathologist to develop a differential diagnosis, which may then be pruned into a specific or likely cause. The aim of the following review is to elucidate these patterns in the context of the liver diseases from which they arise with the goal developing a differential diagnosis and ultimate determination of etiology. Acad Forensic Pathol. 2018 8(2): 256-295.

Clinical outcomes, histopathological patterns, and chemical analysis of Ayurveda and herbal medicine associated with severe liver injury-A single-center experience from southern India

INTRODUCTION

Ayurvedic and herbal medicines (AHM) are known to cause varying degrees of drug-induced liver injury (DILI). Clinical, biochemical, histological spectrum and outcomes of AHM linked to severe DILI are not well studied.

METHODS

Out of 1440 liver disease patients, 94 were found to have a severe liver injury and associated AHM intake. Thirty-three patients were suspected to have AHM-DILI on Roussel Uclaf Causality Assessment Scoring Method. Forty-seven and 30 of retrieved AHM samples were analyzed for heavy metals and hepatotoxic volatile organic compounds (hVOCs), respectively. Eleven patients ingested AHM from unregistered traditional healers (UTH). Clinicopathological outcomes were analyzed in 27 patients (who underwent liver biopsy) and outcomes with respect to chemical analyses were studied in 33 patients.

RESULTS

Males predominated (70.4%) with mean age 46.9±15.8 years. Mean follow up was 119.2±81.4 days. The median duration of drug intake was 28 days (10 - 84). Five patients died (18.5%). Hepatic encephalopathy, hypoalbuminemia, and hepatic necrosis were significantly associated with mortality (p < 0.005). Arsenic and mercury ingestion was significantly associated with death (p < 0.005). hVOCs were detected in more than 70% of samples. AHM intake from UTH was associated with higher mortality.

CONCLUSION

Adequate regulation and scrutiny regarding AHM use among the general population is an unmet need. Early liver biopsy after clinical identification of at-risk patients can expedite definitive treatment with a liver transplant.

IL-33 signalling in liver immune cells enhances drug-induced liver injury and inflammation

OBJECTIVE AND DESIGN

The aim of this study was to investigate the contribution of IL-33/ST2 axis in the onset and progression of acute liver injury using a mice model of drug-induced liver injury (DILI).

MATERIAL AND TREATMENTS

DILI was induced by overdose administration of acetaminophen (APAP) by oral gavage in wild-type BALB/c, ST2-deficient mice and in different bone marrow chimeras. Neutrophils were depleted by anti-Ly6G and macrophages with clodronate liposomes (CLL).

METHODS

Blood and liver were collected for biochemical, immunologic and genetic analyses. Mice were imaged by confocal intravital microscopy and liver non-parenchymal cells and hepatocytes were isolated for flow cytometry, genetic and immunofluorescence studies.

RESULTS

Acetaminophen overdose caused a massive necrosis and accumulation of immune cells within the liver, concomitantly with IL-33 and chemokine release. Liver non-parenchymal cells were the major sensors for IL-33, and amongst them, neutrophils were the major players in amplification of the inflammatory response triggered by IL-33/ST2 signalling pathway.

CONCLUSION

Blockage of IL-33/ST2 axis reduces APAP-mediated organ injury by dampening liver chemokine release and activation of resident and infiltrating liver non-parenchymal cells.

Toxicity and cytochrome P450 1A mRNA induction by 6-formylindolo[3,2-b]carbazole (FICZ) in chicken and Japanese quail embryos

The tryptophan derivative formylindolo[3,2-b]carbazole (FICZ) binds with high ligand affinity to the aryl hydrocarbon receptor (AHR) and is readily degraded by AHR-regulated cytochrome P450 family 1 (CYP1) enzymes. Whether in vivo exposure to FICZ can result in toxic effects has not been examined and the main objective of this study was to determine if FICZ is embryotoxic in birds. We examined toxicity and CYP1 mRNA induction of FICZ in embryos from chicken (Gallus domesticus) and Japanese quail (Coturnix japonica) exposed to FICZ (2-200μgkg(-1)) by yolk and air sac injections. FICZ caused liver toxicity, embryo mortality, and CYP1A4 and CYP1A5 induction in both species with similar potency. This is in stark contrast to the very large difference in sensitivity of these species to halogenated AHR agonists. We also exposed chicken embryos to a low dose of FICZ (4μgkg(-1)) in combination with a CYP inhibitor, ketoconazole (KCZ). The mixture of FICZ and KCZ was lethal while FICZ alone had no effect at 4μgkg(-1). Furthermore, mixed exposure to FICZ and KCZ caused stronger and more long-lasting hepatic CYP1A4 induction than exposure to each compound alone. These findings indicate reduced biotransformation of FICZ by co-treatment with KCZ as a cause for the enhanced effects although additive AHR activation is also possible. To conclude, FICZ is toxic to bird embryos and it seems reasonable that the toxicity by FICZ involves AHR activation. However, the molecular targets and biological events leading to hepatic damage and mortality are unknown.

Plasma osteopontin in acute liver failure

BACKGROUND

Osteopontin (OPN) is a novel phosphoglycoprotein expressed in Kupffer cells that plays a pivotal role in activating natural killer cells, neutrophils and macrophages. Measuring plasma OPN levels in patients with acute liver failure (ALF) might provide insights into OPN function in the setting of massive hepatocyte injury.

METHODS

OPN levels were measured using a Quantikine® ELISA assay on plasma from 105 consecutive ALF patients enrolled by the US Acute Liver Failure Study Group, as well as controls including 40 with rheumatoid arthritis (RA) and 35 healthy subjects both before, and 1 and 3 days after undergoing spine fusion (SF) surgery as a model for acute inflammation.

RESULTS

Median plasma OPN levels across all etiologies of ALF patients were elevated 10- to 30-fold: overall median 1055ng/mL; range: 33-19,127), when compared to healthy controls (median in pre-SF patients: 41ng/mL; range 2.6-86.4). RA and SF post op patients had elevated OPN levels (37ng/mL and 198ng/mL respectively), well below those of the ALF patients. Median OPN levels were highest in acetaminophen (3603ng/mL) and ischemia-related ALF (4102ng/mL) as opposed to viral hepatitis (706ng/mL), drug-induced liver injury (353ng/mL) or autoimmune hepatitis (436ng/mL), correlating with the degree of hepatocellular damage, as reflected by aminotransferase values (R value: 0.47 for AST, p<0.001).

CONCLUSIONS

OPN levels appeared to correlate with degree of liver necrosis in ALF. Very high levels were associated with hyperacute injury and good outcomes. Whether OPN exerts a protective effect in limiting disease progression in this setting remains uncertain.