Acetaminophen-induced Liver Failure Research Articles

Experimental model of systemic inflammation during acetaminophen toxicity

Acetaminophen is one of the most toxic drugs that can cause liver damage. At the same time, acetaminophen-induced liver failure is closely associated with the development of systemic inflammatory response syndrome. However, there is no drug aimed at suppressing the systemic inflammatory response. That is, this issue needs to be studied experimentally, but a model of systemic inflammation during acetaminophen overdose has not yet been obtained. Therefore, it was decided to develop an experimental model of systemic inflammation during acetaminophen overdose. The purpose of this study was to experimentally substantiate the semi-lethal dose for acetaminophen overdose in C57Bl/6 mice and to evaluate the readings of blood tests after administration of the drug. To determine the semi-lethal dose, male C57Bl/6 mice were intraperitoneally injected with “Ifimol” (Unique Pharmaceutical Laboratories, India) or acetaminophen solution (Sigma-Aldrich, USA) with a concentration of 14 mg/ml in different doses. When introducing “Ifimol”, it was not possible to achieve a semi-lethal dose. When administering a solution of acetaminophen, 50% mortality was recorded at a dose of 600 mg/kg body weight. After establishing a semi-lethal dose, the experimental group was administered an acetaminophen solution (Sigma-Aldrich, USA) with a concentration of 14 mg/ml at a dose of 600 mg/kg. The control group was injected with saline in an equivalent volume. On the second day, liver and peripheral blood samples were taken. Subsequently, hematological and biochemical blood tests and histological analysis were performed. Histological examination revealed centrilobular necrosis and disorganization of the liver structure. According to the biochemical blood test, the activity of aspartate aminotransferase, alanine aminotransferase, creatinine concentration, and the de Ritis coefficient differed statistically significantly (p 0.05) in the experimental group compared to the control group. Among the hematological blood test parameters, there were statistically significant differences in the number of leukocytes, platelets, as well as the absolute and relative content of granulocytes and lymphocytes. Thus, 48 hours after administration of a semi-lethal dose of acetaminophen, there were signs of damage to internal organs (liver, kidneys) and changes in immune system parameters, which are similar to components of systemic inflammation in humans.

Preclinical efficacy and safety of encapsulated proliferating human hepatocyte organoids in treating liver failure

Alginate-encapsulated hepatocyte transplantation is a promising strategy to treat liver failure. However, its clinical application was impeded by the lack of primary human hepatocytes and difficulty in controlling their quality. We previously reported proliferating human hepatocytes (ProliHHs). Here, quality-controlled ProliHHs were produced in mass and engineered as liver organoids to improve their maturity. Encapsulated ProliHHs liver organoids (eLO) were intraperitoneally transplanted to treat liver failure animals. Notably, eLO treatment increased the survival of mice with post-hepatectomy liver failure (PHLF) and ameliorated hyperammonemia and hypoglycemia by providing liver functions. Additionally, eLO treatment protected the gut from PHLF-augmented permeability and normalized the increased serum endotoxin and inflammatory response, which facilitated liver regeneration. The therapeutic effect of eLO was additionally proved in acetaminophen-induced liver failure. Furthermore, we performed assessments of toxicity and biodistribution, demonstrating that eLO had no adverse effects on animals and remained non-tumorigenic.

Genista cephalantha Spach. protects against acetaminophen-induced liver failure via preserving the glutathione redox system, reducing inflammatory response, and inhibiting hepatocyte death in rats.

The current study was conducted to assess the protective mechanisms of n-BuOH fraction from the aerial part of Genista cephontala (BEGC) on APAP-induced liver injury compared to necrostatine-1 (Nec-1). A model of APAP-induced hepatotoxicity was created in male rats by injecting a single dose; 1000 mg/kg APAP, the protective effect was performed with (200 mg/kg; 10 days) BEGC compared to Nec-1, (1.8 mg/kg). BEGC or NeC-1 pretreatment significantly abolished impaired effects in APAP-rats, by decreasing the generation of TBARS and ROS in mitochondrial and cytosolic fractions and maintaining liver function activities. A marked response was observed in the levels of both GSH and GSH-system enzymes in liver homogenates and mitochondrial fractions to BEGC. BEGC/ Nec-1 successfully regulated the inflammatory mediators (IL-β, TNF-α, HMGB1, and acHMGB1) and MPO levels. During APAP treatment, no caspase-3 or -8 activity was detected, and the level of fk18; M30 was higher than the levels of cck18; M65. Moreover, RIPK3 and MLKL levels were increased in the APAP group. These results suggested that necroptosis predominates during the APAP liver injury model. Interestingly, these necroptotic factors were significantly down-regulated by BEGC treatment. Both biochemical and histopathological findings were consistent with each other. From all these findings, the hepatoprotective effect of BEGC could be due to the abundance of polyphenols identified by LC-MS/MS analysis, as well as the synergistic interactions of all contents.

Anti-miR-873-5p improves alcohol-related liver disease by enhancing hepatic deacetylation via SIRT1

Current therapies for the treatment of alcohol-related liver disease (ALD) have proven largely ineffective. Patients relapse and the disease progresses even after liver transplantation. Altered epigenetic mechanisms are characteristic of alcohol metabolism given excessive acetate and NAD depletion and play an important role in liver injury. In this regard, novel therapeutic approaches based on epigenetic modulators are increasingly proposed. MicroRNAs, epigenetic modulators acting at the post-transcriptional level, appear to be promising new targets for the treatment of ALD. MiR-873-5p levels were measured in 23 liver tissue from Patients with ALD, and GNMT levels during ALD were confirmed using expression databases (transcriptome n= 62, proteome n= 68). High-resolution proteomics and metabolomics in mice following the Gao-binge model were used to investigate miR-873-5p expression in ALD. Hepatocytes exposed to 50mM alcohol for 12h were used to study toxicity. The effect of anti-miR-873-5p in the treatment outcomes of ALD was investigated. The analysis of human and preclinical ALD samples revealed increased expression of miR-873-5p in the liver. Interestingly, there was an inverse correlation with NNMT, suggesting a novel mechanism for NAD depletion and aberrant acetylation during ALD progression. High-resolution proteomics and metabolomics identified miR-873-5p as a key regulator of NAD metabolism and SIRT1 deacetylase activity. Anti-miR-873-5p reduced NNMT activity, fuelled the NAD salvage pathway, restored the acetylome, and modulated the levels of NF-κB and FXR, two known SIRT1 substrates, thereby protecting the liver from apoptotic and inflammatory processes, and improving bile acid homeostasis. These data indicate that targeting miR-873-5p, a repressor of GNMT previously associated with NAFLD and acetaminophen-induced liver failure. is a novel and attractive approach to treating alcohol-induced hepatoxicity. The role of miR-873-5p has not been explicitly examined in the progression of ALD, a pathology with no therapeutic options. In this study, inhibiting miR-873-5p exerted hepatoprotective effects against ALD through rescued SIRT1 activity and consequently restored bile acid homeostasis and attenuated the inflammatory response. Targeting hepatic miR-873-5p may represent a novel therapeutic approach for the treatment of ALD.

Fomepizole Therapy for Acetaminophen-Induced Liver Failure in an Infant.

Acetaminophen overdose is common in the pediatric population. N-acetylcysteine (NAC) is effective at preventing liver injury in most patients when started shortly after the overdose. Delays to therapy increase risk of hepatotoxicity and liver failure that may necessitate organ transplant. Animal studies have demonstrated fomepizole may provide added benefit in acetaminophen overdose because of its ability to block the metabolic pathway that produces the toxic acetaminophen metabolite and downstream inhibition of oxidative stress pathways that lead to cell death. Several adult case reports describe use of fomepizole in patients at higher risk for poor outcomes despite NAC. We describe a case of a 7-month-old female who presented in acute liver failure with persistently elevated acetaminophen concentration secondary to repeated supratherapeutic doses of acetaminophen to manage fever. Fomepizole and NAC antidotes were used in the management of the patient. She fully recovered despite demonstrating multiple markers of poor outcome on initial presentation. Although randomized trials are lacking, this case suggests that fomepizole may safely provide additional benefit in pediatric patients at risk for severe acetaminophen toxicity.

Commentary on “Robust coagulation activation and coagulopathy in mice with experimental acetaminophen-induced liver failure”

Commentary on “Robust coagulation activation and coagulopathy in mice with experimental acetaminophen-induced liver failure”

Alleviation of acetaminophen-induced liver failure using silibinin nanoliposomes: An in vivo study

BackgroundAcetaminophen (Act) overdose is a known inducer of liver failure in both children and adults. Cell annihilation ensues following acetaminophen overdose and its toxic metabolites by depleting cellular GSH storage and increasing ROS levels. Silymarin extract and its major compound silibinin (SLB) possess robust antioxidant properties by inducing ROS elimination; however, low bioavailability and rapid metabolism limit their applications. Herein, we aimed at using SLB liposomes to combat acetaminophen-induced acute liver toxicity. MethodsWe have developed a SLB-lipid complex to improve SLB loading efficiency within nanoliposome by using the lipid film method. Liposomes were characterized by using DLS and TEM analysis, and the release pattern, and toxicity profile on the normal cells as well as histopathological and serum analysis were investigated to reveal relevant enzyme activities in an animal model. ResultsData demonstrated that negatively-charged SLB liposomes of 115 nm had homogeneous spherical morphology, and entrapped a considerable quantity of SLB of almost 40%. Liposomes shows a favorable release pattern and were not toxic against NIH3T3 mouse fibroblast cells. The animal study revealed that treatment of mice with SLB nanoliposomes could significantly preserve liver function as revealed by the reduced levels of ALT and AST hepatic enzymes as well as ALP in the serum. Our data indicated that intraperitoneal administration of SLB Lip could significantly reduce ALT enzyme levels (p < 0.05) compared to N-acetylcysteine, while i.v administration resulted in no significant difference compared to control animals with no treatment. ConclusionThe results of this study support the significant hepatoprotective effect of SLB nanoliposomes against acetaminophen-induced toxicity depending on the route of administration.

Essential Involvement of Neutrophil Elastase in Acute Acetaminophen Hepatotoxicity Using BALB/c Mice.

Intense neutrophil infiltration into the liver is a characteristic of acetaminophen-induced acute liver injury. Neutrophil elastase is released by neutrophils during inflammation. To elucidate the involvement of neutrophil elastase in acetaminophen-induced liver injury, we investigated the efficacy of a potent and specific neutrophil elastase inhibitor, sivelestat, in mice with acetaminophen-induced acute liver injury. Intraperitoneal administration of 750 mg/kg of acetaminophen caused severe liver damage, such as elevated serum transaminase levels, centrilobular hepatic necrosis, and neutrophil infiltration, with approximately 50% mortality in BALB/c mice within 48 h of administration. However, in mice treated with sivelestat 30 min after the acetaminophen challenge, all mice survived, with reduced serum transaminase elevation and diminished hepatic necrosis. In addition, mice treated with sivelestat had reduced NOS-II expression and hepatic neutrophil infiltration after the acetaminophen challenge. Furthermore, treatment with sivelestat at 3 h after the acetaminophen challenge significantly improved survival. These findings indicate a new clinical application for sivelestat in the treatment of acetaminophen-induced liver failure through mechanisms involving the regulation of neutrophil migration and NO production.

Robust coagulation activation and coagulopathy in mice with experimental acetaminophen-induced liver failure

BackgroundPatients with acetaminophen (APAP)-induced acute liver failure (ALF) display both hyper- and hypocoagulable changes not necessarily recapitulated by standard hepatotoxic doses of APAP used in mice (eg, 300 mg/kg). ObjectivesWe sought to examine coagulation activation in vivo and plasma coagulation potential ex vivo in experimental settings of APAP-induced hepatotoxicity and repair (300-450 mg/kg) and APAP-induced ALF (600 mg/kg) in mice. ResultsAPAP-induced ALF was associated with increased plasma thrombin–antithrombin complexes, decreased plasma prothrombin, and a dramatic reduction in plasma fibrinogen compared with lower APAP doses. Hepatic fibrin(ogen) deposits increased independent of APAP dose, whereas plasma fibrin(ogen) degradation products markedly increased in mice with experimental ALF. Early pharmacologic anticoagulation (+2 hours after 600 mg/kg APAP) limited coagulation activation and reduced hepatic necrosis. The marked coagulation activation evident in mice with APAP-induced ALF was associated with a coagulopathy detectable ex vivo in plasma. Specifically, prolongation of the prothrombin time and inhibition of tissue factor–initiated clot formation were evident even after restoration of physiological fibrinogen concentrations. Plasma endogenous thrombin potential was similarly reduced at all APAP doses. Interestingly, in the presence of ample fibrinogen, ∼10 times more thrombin was required to clot plasma from mice with APAP-induced ALF compared with plasma from mice with simple hepatotoxicity. ConclusionThe results indicate that robust pathologic coagulation cascade activation in vivo and suppressed coagulation ex vivo are evident in mice with APAP-induced ALF. This unique experimental setting may fill an unmet need as a model to uncover mechanistic aspects of the complex coagulopathy of ALF.

Engineered human liver based on pullulan-dextran hydrogel promotes mice survival after liver failure.

Liver tissue engineering approaches aim to support drug testing, assistance devices, or transplantation. However, their suitability for clinical application remains unsatisfactory. Herein, we demonstrate the beneficial and biocompatible use of porous pullulan-dextran hydrogel for the self-assembly of hepatocytes and biliary-like cells into functional 3D microtissues. Using HepaRG cells, we obtained 21 days maintenance of engineered liver polarity, functional detoxification and excretion systems, as well as glycogen storage in hydrogel. Implantation on two liver lobes in mice of hydrogels containing 3800 HepaRG 3D structures of 100​μm in diameter, indicated successful engraftment and no signs of liver toxicity after one month. Finally, after acetaminophen-induced liver failure, when mice were transplanted with engineered livers on left lobe and peritoneal cavity, the survival rate at 7 days significantly increased by 31.8% compared with mice without cell therapy. These findings support the clinical potential of pullulan-dextran hydrogel for liver failure management.

Paracrine effects of stem cell conditioned medium on production of oxygen reactive species in blood neutrophils in acetaminophen-induced liver failure

The current study examined the effects of mesenchymal stem cells-derived conditioned medium on the severity of systemic inflammatory response induced by the administration of acetaminophen, as well as its long-term effects on hepatic tissues. A conditioned medium fraction ˂30 кDа showed maximum protective effect. Proteins of this fraction reduce the degree of systemic inflammatory response and liver tissue fibrosis long after the toxin administration. Liver tissues from experimental animals were examined, and a correlation between the reduction of granulocytic infiltration scoring and the degree hepatic parenchymal necrosis was demonstrated (confirmed by the cytolytic enzyme level). The ˂30 кDа fraction increased the spontaneous but decreased phobrol-12-myristate-13-acetate-induced intracellular production of reactive oxygen species. Results from this study show that the level of macrophage migration inhibitory factor and expression of thioredoxin significantly increase as compared to controls during increased spontaneous production of reactive oxygen species in neutrophils.

Paracrine Effects of Stem Cell Conditioned Medium on Reactive Oxygen Species Production in Blood Neutrophils in Acetaminophen-Induced Liver Failure

Paracrine Effects of Stem Cell Conditioned Medium on Reactive Oxygen Species Production in Blood Neutrophils in Acetaminophen-Induced Liver Failure

Reactive Microgliosis in Sepsis-Associated and Acute Hepatic Encephalopathies: An Ultrastructural Study.

Sepsis and acute liver failure are associated with severe endogenous intoxication. Microglia, which are the resident immune brain cells, play diverse roles in central nervous system development, surveillance, and defense, as well as contributing to neuroinflammatory reactions. In particular, microglia are fundamental to the pathophysiology of reactive toxic encephalopathies. We analyzed microglial ultrastructure, morphotypes, and phagocytosis in the sensorimotor cortex of cecal ligation and puncture (CLP) and acetaminophen-induced liver failure (AILF) Wistar rats. A CLP model induced a gradual shift of ~50% of surveillant microglia to amoeboid hypertrophic-like and gitter cell-like reactive phenotypes with active phagocytosis and frequent contacts with damaged neurons. In contrast, AILF microglia exhibited amoeboid, rod-like, and hypertrophic-like reactive morphotypes with minimal indications for efficient phagocytosis, and were mostly in contact with edematous astrocytes. Close interactions of reactive microglia with neurons, astrocytes, and blood-brain barrier components reflect an active contribution of these cells to the tissue adaptation and cellular remodeling to toxic brain damage. Partial disability of reactive microglia may affect the integrity and metabolism in all tissue compartments, leading to failure of the compensatory mechanisms in acute endogenous toxic encephalopathies.

IMMUNOHISTOCHEMICAL STUDY OF THE BRAIN AQUAPORIN-4 IN THE RAT ACUTE LIVER FAILURE MODEL

Acute liver failure as well as acute-on-chronic liver failure result in the development of acute hepatic encephalopathy (HE) characterized by the major pathophysiologic event in form of the brain edema formation. Among brain cells, astrocytes are considered to be a central cellular population most sensitive to ammonia exposure in HE being the primarily cellular source of glutamine synthetase for ammonia metabolism. Astrocyte swelling is considered to be a principal sign of acute HE, while the exact molecular mechanisms of this event are still not fully understood. According to current concepts on HE, alteration in AQP4 regulation can play one of the central roles in the brain edema development and progression in hyperammonemia states. Considering high region- and context-specific heterogeneity of astroglial populations in the CNS, AQP4 involvement in the links of HE can also sustain mentioned conventional diversity.&#x0D; The aim of the study: to determine the immunohistochemical level of the brain aquaporin 4 (AQP4) expression in the experimental acute liver failure in rats.&#x0D; Materials and methods. The study was conducted in Wistar rats: 5 sham (control) animals and 10 rats with acetaminophen induced liver failure model (AILF). The immunohistochemical study of AQP4 expression was carried out in the sensorimotor cortex, white matter, hippocampus, thalamus and caudate nucleus/putamen regions between 12 and 24 h after acetaminophen treatment.&#x0D; Results. Starting from the 6th hour after acetaminophen treatment all AILF-animals showed the progressive impairment of clinical signs of acute liver failure, evidenced histologically by spread liver centrilobular necrosis and finished in 6 rats by comatose state up to 24 h (constituted subgroup AILF-B, “non-survived”). 4 animals survived until the 24 h - subgroup AILF-A, “survived”. In the AILF-B group, starting from 16 to 24 hours after acetaminophen treatment, a significant (relative to control) regionally-specific dynamic increase AQP4 levels was observed in the brain: in the cortex – by 405.17 %, hippocampus – by 387.38%, caudate nucleus/putamen – by 314.11%; from 12th hour: in the thalamus – by 342.66% and subcortical white matter – by 297.77%; with the highest elevation of AQP4 expression in the cortex among other studied regions: by 5.05 times.&#x0D; Conclusions. AILF in rats induces dynamic increase in AQP4 levels in the cortex, hippocampus and caudate nucleus/putamen by 12th hours and in the white matter and thalamus – by 16th h after the acetaminophen overdosing with the highest elevation in the cortical region. The heterogeneity in the degree of AQP4 elevation among different brain regions potentially may indicate brain territories more susceptible for systemic toxic exposure and damage in acute liver failure. Furthermore, the earliest reliable increase of AQP4 levels in the cortex, hippocampus and caudate/putamen might propose the faster reactivity of the local astroglial populations in response to the hyperammonemia among other regions. Consequently, the later and lower rates of AQP4 elevation in the white matter might indicate local astroglia as less reactive and/or more protected from the harmful exposure at a certain time period of the experiment. The higher cortical levels of AQP4 in the non-survived animals compared to survived ones reflect the significance of AQP4-involving mechanisms in the aggravation of acute HE, as well as the role of AQP4 alterations in thanatogenesis in the conditions of acute liver failure.

Glutamine synthetase expression in the brain during experimental acute liver failure (immunohistochemical study)

The aim of the study was to determine the immunohistochemical level of glutamine synthetase (GS) expression in different brain regions in the conditions of experimental acute liver failure in rats.&#x0D; Materials and methods. The study was conducted in Wistar rats: 5 sham (control) animals and 10 rats with acetaminophen induced liver failure model (AILF). The immunohistochemical study of GS expression in the sensorimotor cortex, white matter, hippocampus, thalamus, caudate nucleus/putamen was carried out in the period of 12-24 h after acetaminophen treatment.&#x0D; Results. Beginning from the 6th hour after acetaminophen treatment all AILF-animals showed the progressive increase in clinical signs of acute brain disfunction finished in 6 rats by comatose state up to 24 h - they constituted subgroup AILF-B, “non-survived”. 4 animals survived until the 24 h - subgroup AILF-A, “survived”. In the AILF-B group, starting from 16 to 24 hours after treatment, a significant (relative to control) regionally-specific dynamic increase in the level of GS expression was observed in the brain: in the cortex – by 307.33 %, in the thalamus – by 249.47%, in the hippocampus – by 245.53%, in the subcortical white matter – by 126.08%, from 12th hour – in the caudate nucleus/putamen, by 191.66 %; with the most substantive elevation of GS expression in the cortex: by 4.07 times.&#x0D; Conclusion. Starting from the 16th hours after the acetaminophen treatment (from the 12th h in the caudate nucleus/putamen region) and up to 24 h, it is observed reliable compared to control dynamic increase in GS protein expression in the cortex, white matter, hippocampus, thalamus, caudate nucleus/putamen of the rat brain with the most significant elevation in the cortex among other regions. The heterogeneity in the degree of GS expression rising in different brain regions potentially may indicate regions more permeable for ammonia and/or other systemic toxic factors as well as heterogeneous sensitivity of brain regions to deleterious agents in conditions of AILF. Subsequently, revealed diversity in the GS expression reflects the specificity of reactive response of local astroglia in the condition of AILF-encephalopathy during specific time-period. The dynamic increase in the GS expression associated with impairment of animal state, indicates involvement of increased GS levels in the mechanisms of experimental acute hepatic encephalopathy.

Immunohistochemical analysis of microglial changes in the experimental acute hepatic encephalopathy

Hepatic encephalopathy (HE) is a syndrome of impaired brain function in patients with advanced liver failure and it manifests in form of psychometric tests alterations up to decreased consciousness and coma. The current knowledge about HE mainly focused on the theory of ammonia neurotoxicity and neuroinflammation. Microglia being resident innate immune cells of the brain when activated are responsible for the neuroinflammatory reactions. The aim – immunohistochemical study of the microglial changes in different rat brain regions in conditions of experimental acute HE (AHE). Materials and methods. We used acetaminophen induced liver failure model in Wistar rats. Four from 10 animals that survived up to 24 h after acetaminophen injection constituted “compensated group”; 6 animals which died within 24 h – “decompensated group”. Microglial reactive changes were analysed by the evaluation of the relative area (S rel., %) of CD68+ expression in the brain cells not associated with meninges and vessels, as well as the changing in shape and number of these cells. Results. Acetaminophen-induced AHE in rats was characterized by the regional- and time-dependent dynamic increase in CD68 expression level in the rat brain in form of significant (relatively to control) increase of CD68+ S rel. in brain cells and the number of such cells. The medians of CD68+ S rel. and their numbers in significantly changed regions of non-survived rats were, respectively: subcortical white matter – 0.24 (0.20; 0.26) and 11.00 (8.00; 13.00); thalamus – 0.13 (0.90; 0.18) and 6.00 (3.00; 7.00); caudate/putamen – 0.13 (0.12; 0.18) and 7.00 (4.00; 11.00) – all indicators were statistically significant compared to control. In the survived animals, indicators were, respectively: subcortical white matter – 0.24 (0.16; 0,26) and 10.00 (8.00; 12.00); caudate/putamen – 0.12 (0.10; 0.15) and 6.00 (4.00; 10.00) – the differences were significant compared to control. Conclusions. The highest and significant indicators were revealed at 24 h (compared to earlier time points) of the experiment in the white matter, thalamus and caudate/putamen. This fact reflects time-dependent dynamic boosting of reactive changes in microglia and presumably may indicate the regions of the most active neuroinflammatory response within the brain parenchyma in the conditions of AHE. The appearing of a small percentage of cells with amoeboid transformation among CD68+-cells may mean partial functional insufficiency of such cells due to probable suppressive impact of ammonia or other influencing factors, as well as insignificance of the material that needs to be phagocytosed under established conditions.

322: A Fatal Case of Acetaminophen-Induced Liver Failure due to COVID-19 ARDS

INTRODUCTION: Patients with severe acetaminophen toxicity can have fulminant hepatic failure and should be referred early to liver transplant center We present a case of acetaminophen toxicity who could not be transferred due to hypoxia and shock from severe COVID-acute respiratory distress syndrome (ARDS) METHODS: A 43-year-old male with history of HIV, compliant with antiretroviral therapy (most recent CD4 of 686 cells/mcL), was admitted for hypoxia and chills, with concern for COVID-19 based on chest x-ray Per family, he consumed an unknown amount of Tylenol due to persistent fevers Shortly after admission, he became acutely encephalopathic, had a generalized seizure and was transferred to ICU post-intubation Initial lab work showed acetaminophen level 158 ug/mL, alanine aminotransferase and aspartate aminotransferase 1748 and >4500 units/L, respectively Given patient's grade IV encephalopathy, INR 5 0, creatinine 3 0 mg/dL, severe acidosis with pH 6 75 and lactate 18 5 mmol/L, he met criteria for emergent transfer to liver transplant center per King's College Criteria, pending hemodynamic stability Acetaminophen toxicity was treated with triple therapy of high dose N-acetylcysteine (NAC), fomepizole and emergent hemodialysis Due to concern for cerebral edema secondary to hyperammonemia (423 umol/L), patient was considered but too unstable for intracranial pressure (ICP) monitoring He was medically managed with hyperventilation, midazolam drip, hypertonic saline and blood products for coagulopathy Testing returned positive for SARS-CoV-2 and severe COVID-ARDS was managed with lung protective strategies, prone positioning, neuromuscular blockade and dexamethasone Unfortunately, he continued to decompensate with worsening hypoxemia, bradycardia, multiorgan failure and expired within 48 hours RESULTS: This case highlights that COVID-19 patients with persistent fevers and myalgias should be warned against excessive acetaminophen given potential for toxicity and liver failure, possibly inhibited from receiving life-saving therapy due to COVID-ARDS Furthermore, discussions need to be held amongst critical care and transplant teams as to how to approach emergent solid-organ transplant evaluations in COVID patients given risk of initiating necessary peritransplant immunosuppression

Therapeutic Role of Inducible Nitric Oxide Synthase Expressing Myeloid-Derived Suppressor Cells in Acetaminophen-Induced Murine Liver Failure.

BackgroundAcetaminophen (APAP) overdose is one of the major etiologies of liver failure. Hepatocyte necrosis induced by toxic metabolites of APAP can activate proinflammatory responses, including elastase-expressing neutrophils, to exacerbate liver injury. Myeloid-derived suppressor cells (MDSCs) increased in inflammation can inhibit proinflammatory responses. Our aim is to investigate the role of MDSC in APAP-induced liver failure and the possible therapeutic application.MethodsBLAB/c mice were injected with a sublethal/lethal dose of APAP as the murine model of liver failure. MDSCs were defined as CD11b+Gr-1+ cells with the ability of T-cell suppression.ResultsA sublethal challenge of APAP could increase the intrahepatic MDSC and protect mice against subsequent lethal challenge of APAP, lipopolysaccharide (LPS)/D-galatosamine or concanavalin A. This protection was lost if MDSCs were depleted and inducible nitric oxide synthase (iNOS) was the key molecule in this MDSC-mediated protection. Taking advantage of these observations, different bone marrow-derived MDSCs (BM-MDSCs) were generated. Among different cytokine-treated BM-MDSCs, tumor necrosis factor alpha/LPS-primed MDSCs (TNF-α/LPS MDSCs) had the strongest liver-protection ability after adoptive transfer. Further mechanistic explorations showed, iNOS-expressing TNF-α/LPS MDSCs induced the apoptosis of activated neutrophil and decreased the intrahepatic infiltration of elastase-expressing neutrophil. Moreover, we generated MDSCs from human peripheral blood mononuclear cells (PBMCs) with similar phenotype.ConclusionWe demonstrated the protective role of MDSCs and therapeutic effect of TNF-α/LPS MDSCs in APAP-induced liver failure. MDSC might protect against the APAP-induced liver failure by reducing the intrahepatic infiltration of activated neutrophil to limit inflammation. Therefore, a therapeutic role of MDSCs for APAP-induced liver failure was proposed.

Mobilisation and redistribution of multivesicular bodies to the endfeet of reactive astrocytes in acute endogenous toxic encephalopathies

Endogenous toxicity caused by systemic inflammation as well as by acute liver failure triggers a wide range of dysfunctional disorders in the brain ranging from delirium and acute psychosis to coma. Astrocytes, the main homeostatic cells of the central nervous system (CNS), play a key role in pathophysiology of neurotoxic insults. We examined the cecal ligation and puncture (CLP) and acetaminophen-induced liver failure (AILF) of Wistar rats, and analysed ultrastructure of astrocytes in the brain cortex and subcortical white matter of sensorimotor zone with transmission electron microscopy. Both models showed significant similarities in reactive changes of astroglial endosomal machinery. In survived animals (with relative prevalence in the CLP-model), at 24 h after intervention we found an increase in number of multivesicular bodies (MVBs) in astroglial perikarya and astroglial processes. In particular, the number of MVBs substantially (3 times of control values) increased in the perivascular astroglial endfeet. Increased number of MVBs in astrocytes was associated with the lesser degree of intracellular oedema and with signs of compensated oedematous tissue changes. In deceased animals, up to 24 h after intervention, single MVBs were localised mainly in astroglial perikarya, and their number was not significantly changed compared to control. Activation of astroglial endosomal-exosomal machinery in both models reflects the uniform pattern of reactive changes of astroglia in these two systemic conditions and may represent activation of astroglial defence in sepsis-associated encephalopathy (SAE) and acute hepatic encephalopathy (AHE). Our data highlight the special role of astroglial adaptive activity in the counterbalancing of an impaired brain homeostasis under action of endogenous toxins. Accumulation of MVBs in astrocytic processes indicates the activation of their intercellular and gliovascular interactions through endo- and exocytosis in SAE and AHE.

N-acetylcysteine and glycyrrhizin combination: Benefit outcome in a murine model of acetaminophen-induced liver failure.

BACKGROUNDAcetaminophen overdose is the most frequent cause of drug-induced liver failure in developed countries. Substantial progress has been made in understanding the mechanism of hepatocellular injury, but N-acetylcysteine remains the only effective treatment despite its short therapeutic window. Thus, other hepatoprotective drugs are needed for the delayed treatment of acetaminophen-induced hepatotoxicity. Our interest focused on glycyrrhizin for its role as an inhibitor of high mobility group box 1 (HMGB1) protein, a member of the family of damage-associated molecular pattern, known to play an important pathological role in various diseases.AIMTo investigate the efficacy of the N-acetylcysteine/glycyrrhizin combination compared to N-acetylcysteine alone in the prevention of liver toxicity.METHODSEight-week-old C57BL/6J wild-type female mice were used for all our experiments. Mice fasted for 15 h were treated with acetaminophen (500 mg/kg) or vehicle (phosphate-buffered saline) by intraperitoneal injection and separated into the following groups: Glycyrrhizin (200 mg/kg); N-acetylcysteine (150 mg/kg); and N-acetylcysteine/glycyrrhizin. In all groups, mice were sacrificed 12 h following acetaminophen administration. The assessment of hepatotoxicity was performed by measuring plasma levels of alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase. Hepatotoxicity was also evaluated by histological examination of hematoxylin and eosin-stained tissues sections. Survival rates were compared between various groups using Kaplan-Meier curves.RESULTSConsistent with data published in the literature, we confirmed that intraperitoneal administration of acetaminophen (500 mg/kg) in mice induced severe liver injury as evidenced by increases in alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase but also by liver necrosis score. Glycyrrhizin administration was shown to reduce the release of HMGB1 and significantly decreased the severity of liver injury. Thus, the co-administration of glycyrrhizin and N-acetylcysteine was investigated. Administered concomitantly with acetaminophen, the combination significantly reduced the severity of liver injury. Delayed administration of the combination of drugs, 2 h or 6 h after acetaminophen, also induced a significant decrease in hepatocyte necrosis compared to mice treated with N-acetylcysteine alone. In addition, administration of N-acetylcysteine/glycyrrhizin combination was associated with an improved survival rate compared to mice treated with only N-acetylcysteine.CONCLUSIONWe demonstrate that, compared to N-acetylcysteine alone, co-administration of glycyrrhizin decreases the liver necrosis score and improves survival in a murine model of acetaminophen-induced liver injury. Our study opens a potential new therapeutic pathway in the prevention of acetaminophen hepatotoxicity.