Ethyl pyruvate reduces liver injury at early phase but impairs regeneration at late phase in acetaminophen overdose

Dual roles of p62/SQSTM1 in the injury and recovery phases of acetaminophen-induced liver injury in mice

Acetaminophen (APAP) overdose can induce liver injury and is the most frequent cause of acute liver failure in the United States. We investigated the role of p62/SQSTM1 (referred to as p62) in APAP-induced liver injury (AILI) in mice. We found that the hepatic protein levels of p62 dramatically increased at 24 h after APAP treatment, which was inversely correlated with the hepatic levels of APAP-adducts. APAP also activated mTOR at 24 h, which is associated with increased cell proliferation. In contrast, p62 knockout (KO) mice showed increased hepatic levels of APAP-adducts detected by a specific antibody using Western blot analysis but decreased mTOR activation and cell proliferation with aggravated liver injury at 24 h after APAP treatment. Surprisingly, p62 KO mice recovered from AILI whereas the wild-type mice still sustained liver injury at 48 h. We found increased number of infiltrated macrophages in p62 KO mice that were accompanied with decreased hepatic von Willebrand factor (VWF) and platelet aggregation, which are associated with increased cell proliferation and improved liver injury at 48 h after APAP treatment. Our data indicate that p62 inhibits the late injury phase of AILI by increasing autophagic selective removal of APAP-adducts and mitochondria but impairs the recovery phase of AILI likely by enhancing hepatic blood coagulation.

25-Hydroxycholesterol 3-Sulfate Recovers Acetaminophen Induced Acute Liver Injury via Stabilizing Mitochondria in Mouse Models

Acetaminophen (APAP) overdose is one of the most frequent causes of acute liver failure (ALF). N-acetylcysteine (NAC) is currently being used as part of the standard care in the clinic but its usage has been limited in severe cases, in which liver transplantation becomes the only treatment option. Therefore, there still is a need for a specific and effective therapy for APAP induced ALF. In the current study, we have demonstrated that treatment with 25-Hydroxycholesterol 3-Sulfate (25HC3S) not only significantly reduced mortality but also decreased the plasma levels of liver injury markers, including LDH, AST, and ALT, in APAP overdosed mouse models. 25HC3S also decreased the expression of those genes involved in cell apoptosis, stabilized mitochondrial polarization, and significantly decreased the levels of oxidants, malondialdehyde (MDA), and reactive oxygen species (ROS). Whole genome bisulfite sequencing analysis showed that 25HC3S increased demethylation of 5mCpG in key promoter regions and thereby increased the expression of those genes involved in MAPK-ERK and PI3K-Akt signaling pathways. We concluded that 25HC3S may alleviate APAP induced liver injury via up-regulating the master signaling pathways and maintaining mitochondrial membrane polarization. The results suggest that 25HC3S treatment facilitates the recovery and significantly decreases the mortality of APAP induced acute liver injury and has a synergistic effect with NAC in propylene glycol (PG) for the injury.

The dual role of immune response in acetaminophen hepatotoxicity: Implication for immune pharmacological targets

Acetaminophen (APAP), one of the most widely used antipyretic and analgesic drugs, principally contributes to drug-induced liver injury when taken at a high dose. APAP-induced liver injury (AILI) results in extensive necrosis of hepatocytes along with the occurrence of multiple intracellular events such as metabolic activation, cell injury, and signaling pathway activation. However, the specific role of the immune response in AILI remains controversial for its complicated regulatory mechanisms. A variety of inflammasomes, immune cells, inflammatory mediators, and signaling transduction pathways are activated in AILI. These immune components play antagonistic roles in aggravating the liver injury or promoting regeneration. Recent experimental studies indicated that natural products showed remarkable therapeutic effects against APAP hepatotoxicity due to their favorable efficacy. Therefore, this study aimed to review the present understanding of the immune response in AILI and attempted to establish ties among a series of inflammatory cascade reactions. Also, the immune molecular mechanisms of natural products in the treatment of AILI were extensively reviewed, thus providing a fundamental basis for exploring the potential pharmacological targets associated with immune interventions.

The Late-Stage Protective Effect of Mito-TEMPO against Acetaminophen-Induced Hepatotoxicity in Mouse and Three-Dimensional Cell Culture Models

An overdose of acetaminophen (APAP), the most common cause of acute liver injury, induces oxidative stress that subsequently causes mitochondrial impairment and hepatic necroptosis. N-acetyl-L-cysteine (NAC), the only recognized drug against APAP hepatotoxicity, is less effective the later it is administered. This study evaluated the protective effect of mitochondria-specific Mito-TEMPO (Mito-T) on APAP-induced acute liver injury in C57BL/6J male mice, and a three dimensional (3D)-cell culture model containing the human hepatoblastoma cell line HepG2. The administration of Mito-T (20 mg/kg, i.p.) 1 h after APAP (400 mg/kg, i.p.) injection markedly attenuated the APAP-induced elevated serum transaminase activity and hepatic necrosis. However, Mito-T treatment did not affect key factors in the development of APAP liver injury including the activation of c-jun N-terminal kinases (JNK), and expression of the transcription factor C/EBP homologous protein (CHOP) in the liver. However, Mito-T significantly reduced the APAP-induced increase in the hepatic oxidative stress marker, nitrotyrosine, and DNA fragmentation. Mito-T markedly attenuated cytotoxicity induced by APAP in the HepG2 3D-cell culture model. Moreover, liver regeneration after APAP hepatotoxicity was not affected by Mito-T, demonstrated by no changes in proliferating cell nuclear antigen formation. Therefore, Mito-T was hepatoprotective at the late-stage of APAP overdose in mice.

Liver Regeneration after Acetaminophen Hepatotoxicity: Mechanisms and Therapeutic Opportunities

Acetaminophen (N-acetyl-para-aminophenol; APAP) overdose is the most common cause of acute liver failure in the Western world, with limited treatment opportunities. For years, research on APAP overdose has been focused on investigating the mechanisms of hepatotoxicity, with limited success in advancing therapeutic strategies. Acute liver injury after any insult, including APAP overdose, is followed by compensatory liver regeneration, which promotes recovery and is a crucial determinant of the final outcome. Liver regeneration after APAP-induced liver injury is dose dependent and impaired after severe APAP overdose. Although robust regenerative response is associated with spontaneous recovery and survival, impaired regeneration results in faster progression of injury and death after APAP overdose. APAP hepatotoxicity-induced liver regeneration involves a complex time- and dose-dependent interplay of several signaling mediators, including growth factors, cytokines, angiogenic factors, and other mitogenic pathways. Compared with the liver injury, which is established before most patients seek medical attention and has proved difficult to manipulate, liver regeneration can be potentially modulated even in late-stage APAP-induced acute liver failure. Despite recent efforts to study the mechanisms of liver regeneration after APAP-induced liver injury, more comprehensive research in this area is required, especially regarding factors that contribute to impaired regenerative response, to develop novel regenerative therapies for APAP-induced acute liver failure.

DAMPs and sterile inflammation in drug hepatotoxicity

Drug hepatotoxicity is the leading cause of acute liver failure (ALF) in the developed countries. The early diagnosis and treatment are still problematic, and one important reason is the lack of reliable mechanistic biomarkers and therapeutic targets; therefore, searching for new biomarkers and therapeutic targets is urgent. Drug hepatotoxicity induces severe liver cells damage and death. Dead and damaged cells release endogenous damage-associated molecular patterns (DAMPs). Increased circulating levels of DAMPs (HMGB1, histones and DNA) can reflect the severity of drug hepatotoxicity. Elevated plasma HMGB1 concentrations can serve as early and sensitive mechanistic biomarker for clinical acetaminophen hepatotoxicity. DAMPS significantly contribute to liver injury and inhibiting the release of DAMPs ameliorates experimental hepatotoxicity. In addition, HMGB1 mediates 80% of gut bacterial translocation (BT) during acetaminophen toxicity. Gut BT triggers systemic inflammation, leading to multiple organ injury and mortality. Moreover, DAMPs can trigger and extend sterile inflammation, which contributes to early phase liver injury but improves liver regeneration at the late phase of acetaminophen overdose, because anti-inflammatory treatment reduces liver injury at early phase but impairs liver regeneration at late phase of acetaminophen toxicity, whereas pro-inflammatory therapy improves late phase liver regeneration. DAMPs are promising mechanistic biomarkers and could also be the potential therapeutic targets for drug hepatotoxicity. DAMPs-triggered sterile inflammation contributes to liver injury at early phase but improves liver regeneration at later phase of acetaminophen hepatotoxicity; therefore, anti-inflammatory therapy would be beneficial at early phase but should be avoided at the late phase of acetaminophen overdose.

Ethyl pyruvate attenuates acetaminophen-induced liver injury and prevents cellular injury induced by N-acetyl-p-benzoquinone imine

Acetaminophen, a common analgesic/antipyretic, is a frequent cause of acute liver failure in Western countries. The development of an effective cure against acetaminophen hepatotoxicity is crucial. Ethyl pyruvate, an ethyl ester derivative of pyruvic acid, has been identified as a possible candidate against acetaminophen hepatotoxicity in animal experiments. However, the mode of the hepatoprotective action of ethyl pyruvate remains unclear. We examined the hepatoprotective effect of ethyl pyruvate against hepatocyte injury and oxidative stress in a mouse model of acetaminophen hepatotoxicity. In addition, to examine whether ethyl pyruvate has direct hepatocellular protection against acetaminophen hepatotoxicity to counteract the influence of inflammatory cells, such as macrophages, we examined the effects of ethyl pyruvate on cellular injury induced by N-acetyl-p-benzoquinone imine, a toxic metabolite of acetaminophen, in a human hepatocyte cell line, HepG2 cells. Treatment with ethyl pyruvate significantly prevented increases in serum transaminase levels and hepatic centrilobular necrosis induced with an acetaminophen overdose in mice in a dose-dependent manner. Although hepatic DNA fragmentation induced by acetaminophen was also attenuated with ethyl pyruvate, nitrotyrosine formation was not inhibited. Ehyl pyruvate significantly attenuated mitochondria dehydrogenase inactivity induced by N-acetyl-p-benzoquinone imine in HepG2 cells. The attenuating effect was also observed in a rat hepatocyte cell line. Increases in annexin V and propidium iodide-stained cells induced by N-acetyl-p-benzoquinone imine were prevented with ethyl pyruvate in HepG2 cells. Pyruvic acid, a parent compound of ethyl pyruvate, tended to attenuate these changes. The results indicate that ethyl pyruvate has direct hepatocellular protection against N-acetyl-p-benzoquinone imine induced injury observed in acetaminophen overdose. The in vivo and in vitro results suggest that ethyl pyruvate attenuates acetaminophen-induced liver injury via, at least in part, its cellular protective potential.

The Role of Glyoxalase-I (Glo-I), Advanced Glycation Endproducts (AGEs), and Their Receptor (RAGE) in Chronic Liver Disease and Hepatocellular Carcinoma (HCC)

Glyoxalase-I (Glo-I) and glyoxalase-II (Glo-II) comprise the glyoxalase system and are responsible for the detoxification of methylglyoxal (MGO). MGO is formed non-enzymatically as a by-product, mainly in glycolysis, and leads to the formation of advanced glycation endproducts (AGEs). AGEs bind to their receptor, RAGE, and activate intracellular transcription factors, resulting in the production of pro-inflammatory cytokines, oxidative stress, and inflammation. This review will focus on the implication of the Glo-I/AGE/RAGE system in liver injury and hepatocellular carcinoma (HCC). AGEs and RAGE are upregulated in liver fibrosis, and the silencing of RAGE reduced collagen deposition and the tumor growth of HCC. Nevertheless, data relating to Glo-I in fibrosis and cirrhosis are preliminary. Glo-I expression was found to be reduced in early and advanced cirrhosis with a subsequent increase of MGO-levels. On the other hand, pharmacological modulation of Glo-I resulted in the reduced activation of hepatic stellate cells and therefore reduced fibrosis in the CCl₄-model of cirrhosis. Thus, current research highlighted the Glo-I/AGE/RAGE system as an interesting therapeutic target in chronic liver diseases. These findings need further elucidation in preclinical and clinical studies.

HMGB1 and Extracellular Histones Significantly Contribute to Systemic Inflammation and Multiple Organ Failure in Acute Liver Failure

Acute liver failure (ALF) is the culmination of severe liver cell injury from a variety of causes. ALF occurs when the extent of hepatocyte death exceeds the hepatic regenerative capacity. ALF has a high mortality that is associated with multiple organ failure (MOF) and sepsis; however, the underlying mechanisms are still not clear. Emerging evidence shows that ALF patients/animals have high concentrations of circulating HMGB1, which can contribute to multiple organ injuries and mediate gut bacterial translocation (BT). BT triggers/induces systemic inflammatory responses syndrome (SIRS), which can lead to MOF in ALF. Blockade of HMGB1 significantly decreases BT and improves hepatocyte regeneration in experimental acute fatal liver injury. Therefore, HMGB1 seems to be an important factor that links BT and systemic inflammation in ALF. ALF patients/animals also have high levels of circulating histones, which might be the major mediators of systemic inflammation in patients with ALF. Extracellular histones kill endothelial cells and elicit immunostimulatory effect to induce multiple organ injuries. Neutralization of histones can attenuate acute liver, lung, and brain injuries. In conclusion, HMGB1 and histones play a significant role in inducing systemic inflammation and MOF in ALF.

Macrophage-derived IL-1α promotes sterile inflammation in a mouse model of acetaminophen hepatotoxicity

The metabolic intermediate of acetaminophen (APAP) can cause severe hepatocyte necrosis, which triggers aberrant immune activation of liver non-parenchymal cells (NPC). Overzealous hepatic inflammation determines the morbidity and mortality of APAP-induced liver injury (AILI). Interleukin-1 receptor (IL-1R) signaling has been shown to play a critical role in various inflammatory conditions, but its precise role and underlying mechanism in AILI remain debatable. Herein, we show that NLRP3 inflammasome activation of IL-1β is dispensable to AILI, whereas IL-1α, the other ligand of IL-1R1, accounts for hepatic injury by a lethal dose of APAP. Furthermore, Kupffer cells function as a major source of activated IL-1α in the liver, which is activated by damaged hepatocytes through TLR4/MyD88 signaling. Finally, IL-1α is able to chemoattract and activate CD11b⁺Gr-1⁺ myeloid cells, mostly neutrophils and inflammatory monocytes, to amplify deteriorated inflammation in the lesion. Therefore, this work identifies that MyD88-dependent activation of IL-1α in Kupffer cells plays a central role in the immunopathogenesis of AILI and implicates that IL-1α is a promising therapeutic target for AILI treatment.

Ethyl pyruvate is a novel anti-inflammatory agent to treat multiple inflammatory organ injuries

Ethyl pyruvate (EP) is a simple derivative of pyruvic acid, which is an important endogenous metabolite that can scavenge reactive oxygen species (ROS). Treatment with EP is able to ameliorate systemic inflammation and multiple organ dysfunctions in multiple animal models, such as acute pancreatitis, alcoholic liver injury, acute respiratory distress syndrome (ARDS), acute viral myocarditis, acute kidney injury and sepsis. Recent studies have demonstrated that prolonged treatment with EP can ameliorate experimental ulcerative colitis and slow multiple tumor growth. It has become evident that EP has pharmacological anti-inflammatory effect to inhibit multiple early inflammatory cytokines and the late inflammatory cytokine HMGB1 release, and the anti-tumor activity is likely associated with its anti-inflammatory effect. EP has been tested in human volunteers and in a clinical trial of patients undergoing cardiac surgery in USA and shown to be safe at clinical relevant doses, even though EP fails to improve outcome of the heart surgery, EP is still a promising agent to treat patients with multiple inflammatory organ injuries and the other clinical trials are on the way. This review focuses on how EP is able to ameliorate multiple organ injuries and summarize recently published EP investigations.

Graphical Abstract

Asparagine attenuates hepatic injury caused by lipopolysaccharide in weaned piglets associated with modulation of Toll-like receptor 4 and nucleotide-binding oligomerisation domain protein signalling and their negative regulators

Pro-inflammatory cytokines play a key role in many models of hepatic damage. In addition, asparagine (Asn) plays an important role in immune function. We aimed to investigate whether Asn could attenuate lipopolysaccharide (LPS)-induced liver damage. Forty-eight castrated barrows were allotted to four groups including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS + 0.5% Asn; and (4) LPS + 1.0% Asn. After 19 d feeding with control, 0.5 or 1.0% Asn diets, pigs were injected with LPS or saline. Blood and liver samples were obtained at 4 h (early stage) and 24 h (late stage) post-injection. Asn alleviated liver injury, indicated by reduced serum aspartate aminotransferase and alkaline phosphatase activities linearly and quadratically; it increased claudin-1 protein expression linearly and quadratically at 24 h, and less severe liver morphological impairment at 4 or 24 h. In addition, Asn decreased mRNA expression of TNF-α and heat shock protein 70 (HSP70) linearly and quadratically at 4 h; it increased TNF-α mRNA expression, and HSP70 protein expression linearly and quadratically at 24 h. Moreover, Asn increased inducible NO synthase activity linearly and quadratically. Finally, Asn down-regulated the mRNA expression of Toll-like receptor 4 (TLR4) signalling molecules (TLR4, IL-1 receptor-associated kinase 1 (IRAK1), TNF-α receptor-associated factor 6), nucleotide-binding oligomerisation domain protein (NOD) signalling molecules (NOD1, NOD2 and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2 (RIPK2)), and NF-κB p65 linearly or quadratically at 4 h. Oppositely, Asn up-regulated mRNA expressions of TLR4 and NOD signalling molecules (TLR4, myeloid differentiation factor 88, IRAK1, NOD2 and RIPK2), and their negative regulators (radioprotective 105, single Ig IL-1R-related molecule, Erbb2 interacting protein and centaurin β1) linearly or quadratically at 24 h. These results indicate that, in early and late stages of LPS challenge, Asn improves liver integrity and exerts different regulatory effects on mRNA expression of TLR4 and NOD signalling molecules.

Protection afforded by pre- or post-treatment with 4-phenylbutyrate against liver injury induced by acetaminophen overdose in mice

Acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) is a widely used analgesic/antipyretic drug with few adverse effects at therapeutic doses; suicidal or unintentional overdose of APAP frequently induces severe hepatotoxicity. To explore a new and effective antidote for APAP hepatotoxicity, this study examined the effects of sodium 4-phenylbutyrate (4-PBA) on liver injury induced by APAP overdose in mice. Liver injury was induced in C57BL/6 male mice by intraperitoneal injection of APAP (400mg/kg). The effects of 4-PBA (100-200mg/kg) treatment at 1h before the APAP injection were evaluated with serum alanine aminotransferase (ALT) and blood ammonia levels, hepatic pathological changes, including histopathology, DNA damage, nitrotyrosine formation, and mRNA or protein expression involved in the development of hepatotoxicity, such as X-box binding protein-1 (XBP1), c-Jun N-terminal kinase (JNK), C/EBP homologous protein (CHOP) and B-cell lymphoma 2 interacting mediator of cell death (Bim). In addition, glutathione depletion and CYP2E1 protein expression, which are measures of the metabolic conversion of APAP to a toxic metabolite, were examined. Furthermore, we examined the effects of post-treatment with 4-PBA against APAP-induced hepatotoxicity in mice. When administered at 1h before APAP injection, 4-PBA significantly prevented the increase in serum ALT and blood ammonia levels, centrilobular necrosis of hepatocytes, DNA fragmentation, and nitrotyrosine formation induced by APAP in mice. 4-PBA also inhibited hepatic Xbp1 mRNA splicing and JNK phosphorylation induced by APAP, but did not suppress CHOP and Bim mRNA and protein expression. In addition, 4-PBA had little effect on hepatic glutathione depletion and CYP2E1 expression, parameters of toxic APAP metabolite production. Post-treatment with 4-PBA administration at 1 or 2h after APAP injection also attenuated the increase in serum ALT and blood ammonia levels and hepatic pathological changes in APAP-induced hepatotoxicity in mice. Although post-treatment with 4-PBA did not show any effects on hepatic Xbp1 mRNA splicing and JNK phosphorylation, it drastically attenuated the DNA fragmentation induced by APAP. The precise molecular mechanisms of the protection afforded by 4-PBA against APAP hepatotoxicity in mice are unclear, but they seem to involve inhibition of hepatocellular DNA fragmentation. We suggest that 4-PBA is a promising candidate as an antidote against APAP-induced liver injury.

HMGB1 neutralization is associated with bacterial translocation during acetaminophen hepatotoxicity

BACKGROUND

Acetaminophen (APAP) hepatotoxicity is associated with a high rate of gram-negative enteric bacterial infection; however, the underlying mechanism is still unknown. APAP overdose induces massive hepatocyte necrosis, necrotic tissue releases high mobility group B1 (HMGB1) and exogenous HMGB1 is able to induce gut bacterial translocation (BT) in normal mice; therefore, it is possible that HMGB1 mediates gut BT in APAP hepatotoxicity. This study aims to test this hypothesis by using anti-HMGB1 neutralizing antibody to treat APAP overdose for 24-48 hours.

METHODS

Male C57BL/6 mice were intraperitoneally (i.p.) injected with a single dose of APAP (350 mg/kg dissolved in 1 mL sterile saline). 2 hrs after APAP injection, the APAP challenged mice were randomized to receive treatment with either anti-HMGB1 antibody (400 μg per dose) or non-immune (sham) IgG every 24 h for a total of 2 doses.

RESULTS

24 and 48 hrs after APAP challenge, anti-HMGB1 treatment instead of sham IgG therapy significantly decreased serum HMGB1 concentrations and reduced BT by 85%; serum HMGB1 levels were positively correlated with the amount of BT; anti-HMGB1 therapy decreased hepatic BT at 48 h, which was associated with better recovered liver structure and better restored hepatic immune system that was shown by enhanced hepatic mRNA expression of TNF-α, IL-6 and extensive proliferation of inflammatory and reticuloendothelial cells; however, anti-HMGB1 treatment did not decrease gut mucosal permeability as compared to the sham IgG therapy at either 24 or 48 hrs.

CONCLUSION

HMGB1 neutralization is associated with bacterial translocation during APAP hepatotoxicity.

Ethyl pyruvate prevents inflammatory factors release and decreases intestinal permeability in rats with D-galactosamine-induced acute liver failure

BACKGROUND

The pathogenesis and progression of acute liver failure (ALF) are closely associated with intestinal endotoxemia because of the high permeability of the intestinal wall. Treatment with ethyl pyruvate (EP) has been shown to protect liver failure effectively. The current study aimed to explore the relationship between proinflammatory cytokines and intestinal permeability, and to investigate whether EP administration might prevent the release of multiple proinflammatory cytokines and decrease intestinal permeability and therefore, protect the liver from injury.

METHODS

The ALF model was induced by D-galactosamine in rats. The rats were randomly divided into control (saline, i.p.), model (D-galactosamine, 1.2 g/kg, i.p.), prevention [EP injection (40 mg/kg) 2 hours ahead of D-galactosamine] and treatment groups (EP injection 2 hours after D-galactosamine). Samples were obtained at 12 and 24 hours after ALF induction, respectively. The histology of liver and intestinal tissue was assessed. Serum alanine aminotransferase, endotoxin, D(-)-lactate, diamine oxidase (DAO), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) and high mobility group box-1 (HMGB1) were evaluated. The survival of rats was also recorded.

RESULTS

The rats in model group showed severe damage to liver tissue and intestinal mucosa 12 and 24 hours after ALF induction. EP significantly improved liver or intestinal injury. In addition, serum endotoxin, D(-)-lactate, DAO, TNF-alpha, IFN-gamma and HMGB1 levels were significantly increased in the model group compared with the control group. There was a positive correlation between intestinal permeability and proinflammatory cytokines. EP significantly reduced serum endotoxin, D(-)-lactate, DAO, TNF-alpha, IFN-gamma and HMGB1 levels. The median survival time was significantly prolonged in both prevention and treatment groups (126 and 120 hours compared with 54 hours in the model group).

CONCLUSIONS

EP has protective and therapeutic effects on intestinal mucosa. EP decreases intestinal permeability, and inhibits the release of multiple proinflammatory cytokines in rats with ALF.

Ethyl pyruvate for the treatment of acetaminophen intoxication: alternative to N-acetylcysteine?

N-acetylcysteine is the classical antidote for acetaminophen overdose-induced hepatotoxicity, but its efficacy is limited by the need for early and only temporary treatment. Therefore, Yang and colleagues tested the hypothesis of whether ethyl pyruvate - another anti-inflammatory and antioxidant compound, which they had previously shown to protect against liver injury of various other etiologies - may allow circumventing these limitations. While ethyl pyruvate improved liver regeneration when administered early and during a limited period only, the opposite response was present both after delayed as well as prolonged treatment. The authors concluded that prolonged anti-inflammatory treatment is detrimental after acetaminophen intoxication-induced liver damage. On the one hand, this research paper confirms the need for biomarkers to monitor organ recovery after acetaminophen. On the other hand, this paper adds to the ongoing discussion on the usefulness of ethyl pyruvate as a resuscitation fluid in the critically ill.