A metabolomic analysis of thiol response for standard and modified N-acetyl cysteine treatment regimens in patients with acetaminophen overdose

Advances in the understanding of acetaminophen toxicity mechanisms: a clinical toxicology perspective

INTRODUCTION

Acetaminophen (paracetamol) is a commonly used analgesic and antipyretic agent, which is safe in therapeutic doses. Acetaminophen poisoning due to self-harm or repeated supratherapeutic ingestion is a common cause of acute liver injury. Acetylcysteine has been a mainstay of treatment for acetaminophen poisoning for decades and is efficacious if administered early. However, treatment failures occur if administered late, in 'massive' overdoses or in high-risk patients.

AREAS COVERED

This review provides an overview of the mechanisms of toxicity of acetaminophen poisoning (metabolic and oxidative phase) and how this relates to the assessment and treatment of the acetaminophen poisoned patient. The review focuses on how these advances offer further insight into the utility of novel biomarkers and the role of proposed adjunct treatments.

EXPERT OPINION

Advances in our understanding of acetaminophen toxicity have allowed the development of novel biomarkers and a better understanding of how adjunct treatments may prevent acetaminophen toxicity. Newly proposed adjunct treatments like fomepizole are being increasingly used without robust clinical trials. Novel biomarkers (not yet clinically available) may provide better assessment of these newly proposed adjunct treatments, particularly in clinical trials. These advances in our understanding of acetaminophen toxicity and liver injury hold promise for improved diagnosis and treatment.

Chemoselective bicyclobutane-based mass spectrometric detection of biological thiols uncovers human and bacterial metabolites

Sulfur is an essential element of life. Thiol-containing metabolites in all organisms are involved in the regulation of diverse biological processes. Especially, the microbiome produces bioactive metabolites or biological intermediates of this compound class. The analysis of thiol-containing metabolites is challenging due to the lack of specific tools, making these compounds difficult to investigate selectively. We have now developed a new methodology comprising bicyclobutane for chemoselective and irreversible capturing of this metabolite class. We utilized this new chemical biology tool immobilized onto magnetic beads for the investigation of human plasma, fecal samples, and bacterial cultures. Our mass spectrometric investigation detected a broad range of human, dietary and bacterial thiol-containing metabolites and we even captured the reactive sulfur species cysteine persulfide in both fecal and bacterial samples. The described comprehensive methodology represents a new mass spectrometric strategy for the discovery of bioactive thiol-containing metabolites in humans and the microbiome.

Distinct transcriptomic and metabolomic profiles characterize NSAID-induced urticaria/angioedema patients undergoing aspirin desensitization

BACKGROUND

There is limited data on the mechanisms of aspirin desensitization in patients with nonsteroidal anti-inflammatory drug (NSAID)-induced urticaria/angioedema (NIUA).

OBJECTIVES

We sought to characterize the transcriptomic and metabolomic profiles of patients with NIUA undergoing aspirin desensitization.

METHODS

PBMCs and plasma were separated from the blood of patients with NIUA undergoing aspirin desensitization for coronary artery disease and NSAID-tolerant controls. RNA was isolated from PBMCs and subjected to messenger RNA (mRNA)- and long noncoding RNA (lncRNA)-sequencing. Plasma samples were analyzed using LC-MS/MS for metabolite shifts using a semitargeted metabolomics panel.

RESULTS

Eleven patients with NIUA and 10 healthy controls were recruited. The mRNA gene profiles of predesensitization versus postdesensitization and healthy control versus postdesensitization did not differ significantly. However, we identified 739 mRNAs and 888 lncRNAs as differentially expressed from preaspirin desensitization patients and controls. A 12-mRNA gene signature was trained using a machine learning algorithm to distinguish between controls, postdose, and predose samples. Ingenuity Pathway Analysis identified 5 canonical pathways that were significantly enriched in preaspirin desensitization samples. IL-22 was the most upregulated pathway. To investigate the potential regulatory roles of the differentially expressed lncRNA on the mRNAs, 9 lncRNAs and 12 mRNAs showed significantly correlated expression patterns in the IL-22 pathway. To validate the transcriptomics data, IL-22 was measured in the plasma samples of the subjects using ELISA. IL-22 was significantly higher in preaspirin desensitization patients compared with controls. In parallel, metabolomic analysis revealed stark differences in plasma profiles of preaspirin desensitization patients and healthy controls. In particular, 2-hydroxybenzoic acid (salicylic acid) was significantly lower in preaspirin desensitization patients compared with healthy controls.

CONCLUSIONS

This is the first study to combine both transcriptomic and metabolomic approaches in patients with NIUA, which contributes to a deeper understanding about the pathogenesis of NIUA and may potentially pave the way toward a molecular diagnosis of NSAID hypersensitivity.

Rosmarinic acid alleviates acetaminophen-induced hepatotoxicity by targeting Nrf2 and NEK7-NLRP3 signaling pathway

Rosmarinic acid (RA) is a natural polyphenol with various biological activities, such as anti-oxidative, anti-fibrotic, and hepatoprotective properties. The objective of this study was to investigate the protective effect of RA against acetaminophen (APAP)-induced hepatotoxicity (AILI) and explore the underlying mechanisms. Kunming mice were treated with RA (20, 40, or 80 mg/kg, i.g) for 7d, followed by an intraperitoneal injection of APAP (500 mg/kg). The liver injury was evaluated by serum biochemical and liver histopathological examinations. Human HepG2 cells were pre-treated with RA (20, 40, or 80 μmol/L) and then incubated with APAP (25 mmol/L) for 24 h. The MTT assay, wound healing assay, transwell migration assay, flow cytometry, and western blotting were employed to further evaluate RA's protective effects on AILI and explore the mechanisms. The results indicated that RA pre-treatment lowered the serum ALT and AST levels, ameliorated the histological damage to the liver, and reduced ROS generation and the production of IL-1β and IL-18 in the liver tissues in APAP-treated mice. Moreover, pre-treatment with RA could promote the cell viability and migration ability and inhibit apoptosis in APAP-treated HepG2 cells. Mechanistically, RA could significantly suppress the APAP-induced activation of the NEK7-NLRP3 signaling pathway. Notably, depletion of Nrf2 by short hairpin RNA (shRNA) partly eliminated the protective effects of RA on AILI and the suppression of NEK7-NLRP3 signaling by RA. In summary, these results indicate that RA has a protective role against AILI through Nrf2-mediated inhibition of ROS production and suppression of the NEK7-NLRP3 pathway.

Ferulic acid ameliorates acetaminophen-induced acute liver injury by promoting AMPK-mediated protective autophagy

Acetaminophen (APAP), one of the most widely used antipyretics and analgesics, principally results in acute liver injury (ALI) in developed countries when taken overdose. Ferulic acid (FA) is a natural polyphenol compound existing in many plants that has free radical scavenging, anti-inflammatory and liver-protective properties. However, the effect and underlying mechanism of FA in treating APAP-induced ALI have not been fully elucidated. Herein, we established a mouse model of APAP-induced ALI and used APAP-stimulated mouse primary hepatocytes for biochemical assessment of molecular parameters. After constructing networks and obtaining predicted targets from public databases, we further verified the putative pathways using immune-blotting assays both in vivo and in vitro. The reign of liver necrosis, serum levels of ALT and AST and oxidative stress in livers significantly elevated after APAP treatment, which were almost recovered back to normal levels by FA administration. In addition, FA significantly upregulated the APAP-induced downregulation of hepatic specific markers, including HNF4a, Foxa2 and ALB. Then, the results of functional enrichment indicated the possible signaling pathways of FA against APAP challenge, mainly including AMPK, autophagy, apoptosis and other metabolic process. Furthermore, FA markedly reversed the APAP-induced decline of mitochondria membrane potential, increased ratio of BAX/BCL2 and CASPASE 3 expression, and promoted autophagy flux of hepatocytes by upregulating AMPK phosphorylation, which were abrogated by a specific AMPK inhibitor, compound C. Overall, the hepatoprotective effect of FA on APAP-induced ALI might be associated with anti-oxidant and anti-apoptosis, which were at least partly attributed to AMPK-mediated protective autophagy.