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Omega‑3 polyunsaturated fatty acids inhibit IL‑11/STAT3 signaling in hepatocytes during acetaminophen hepatotoxicity.

ABSTRACT: Omega‑3 polyunsaturated fatty acids (n‑3 PUFAs) exert a negative effect on IL‑6 production in several liver disorders, including cirrhosis, acute liver failure and fatty liver disease. However, its effect on the production of IL‑11, another important IL‑6 family cytokine, remains unclear. IL‑11 was found to be significantly elevated in acetaminophen (APAP)‑induced liver damage. The aim of the present study was to investigate whether and how n‑3 PUFAs modulate IL‑11 production during APAP‑induced liver injury. For that purpose, wild‑type (WT) and fat‑1 transgenic mice were intraperitoneally injected with APAP to induce liver injury. Serum was collected for ELISA and alanine aminotransferase assay. The hepatocytes of APAP‑injected mice were isolated for reverse transcription‑quantitative PCR and western blot analyses. For the in vitro study, primary hepatocytes isolated from WT or fat‑1 mice were stimulated with APAP. The results revealed that both endogenous and exogenous n‑3 PUFAs significantly aggravated APAP‑induced liver damage via the downregulation of STAT3 signaling. Notably, n‑3 PUFAs inhibited IL‑11 expression, but not IL‑6 expression in hepatocytes during the APAP challenge. Furthermore, it was demonstrated that limited phosphorylation of ERK1/2 and Fos‑like‑1 (Fra‑1) expression are responsible for the n‑3 PUFA‑mediated inhibitory effect on IL‑11 production in APAP‑treated hepatocytes. It was concluded that n‑3 PUFAs inhibit IL‑11 production and further STAT3 activation in hepatocytes during APAP‑induced liver injury. Therefore, ERK1/2‑mediated Fra‑1 expression is responsible for the effect of n‑3 PUFAs on IL‑11 expression.

SUBMITTER: Liu Y

PROVIDER: S-EPMC8416141 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background & aimsAcetaminophen (APAP) overdose remains a frequent cause of acute liver failure, which is generally accompanied by increased levels of serum bile acids (BAs). However, the pathophysiological role of BAs remains elusive. Herein, we investigated the role of BAs in APAP-induced hepatotoxicity.MethodsWe performed intravital imaging to investigate BA transport in mice, quantified endogenous BA concentrations in the serum of mice and patients with APAP overdose, analyzed liver tissue and bile by mass spectrometry and MALDI-mass spectrometry imaging, assessed the integrity of the blood-bile barrier and the role of oxidative stress by immunostaining of tight junction proteins and intravital imaging of fluorescent markers, identified the intracellular cytotoxic concentrations of BAs, and performed interventions to block BA uptake from blood into hepatocytes.ResultsPrior to the onset of cell death, APAP overdose causes massive oxidative stress in the pericentral lobular zone, which coincided with a breach of the blood-bile barrier. Consequently, BAs leak from the bile canaliculi into the sinusoidal blood, which is then followed by their uptake into hepatocytes via the basolateral membrane, their secretion into canaliculi and repeated cycling. This, what we termed 'futile cycling' of BAs, led to increased intracellular BA concentrations that were high enough to cause hepatocyte death. Importantly, however, the interruption of BA re-uptake by pharmacological NTCP blockage using Myrcludex B and Oatp knockout strongly reduced APAP-induced hepatotoxicity.ConclusionsAPAP overdose induces a breach of the blood-bile barrier which leads to futile BA cycling that causes hepatocyte death. Prevention of BA cycling may represent a therapeutic option after APAP intoxication.Lay summaryOnly one drug, N-acetylcysteine, is approved for the treatment of acetaminophen overdose and it is only effective when given within ∼8 hours after ingestion. We identified a mechanism by which acetaminophen overdose causes an increase in bile acid concentrations (to above toxic thresholds) in hepatocytes. Blocking this mechanism prevented acetaminophen-induced hepatotoxicity in mice and evidence from patients suggests that this therapy may be effective for longer periods after ingestion compared to N-acetylcysteine.

Project description:Acetaminophen (APAP) is one of the most popular and safe pain medications worldwide. However, due to its wide availability, it is frequently implicated in intentional or unintentional overdoses where it can cause severe liver injury and even acute liver failure (ALF). In fact, APAP toxicity is responsible for 46% of all ALF cases in the United States. Early mechanistic studies in mice demonstrated the formation of a reactive metabolite, which is responsible for hepatic glutathione depletion and initiation of the toxicity. This insight led to the rapid introduction of N-acetylcysteine as a clinical antidote. However, more recently, substantial progress was made in further elucidating the detailed mechanisms of APAP-induced cell death. Mitochondrial protein adducts trigger a mitochondrial oxidant stress, which requires amplification through a MAPK cascade that ultimately results in activation of c-jun N-terminal kinase (JNK) in the cytosol and translocation of phospho-JNK to the mitochondria. The enhanced oxidant stress is responsible for the membrane permeability transition pore opening and the membrane potential breakdown. The ensuing matrix swelling causes the release of intermembrane proteins such as endonuclease G, which translocate to the nucleus and induce DNA fragmentation. These pathophysiological signaling mechanisms can be additionally modulated by removing damaged mitochondria by autophagy and replacing them by mitochondrial biogenesis. Importantly, most of the mechanisms have been confirmed in human hepatocytes and indirectly through biomarkers in plasma of APAP overdose patients. The extensive necrosis caused by APAP overdose leads to a sterile inflammatory response. Although recruitment of inflammatory cells is necessary for removal of cell debris in preparation for regeneration, these cells have the potential to aggravate the injury. This review touches on the newest insight into the intracellular mechanisms of APAP-induced cells death and the resulting inflammatory response. Furthermore, it discusses the translation of these findings to humans and the emergence of new therapeutic interventions.

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Omega‑3 polyunsaturated fatty acids inhibit IL‑11/STAT3 signaling in hepatocytes during acetaminophen hepatotoxicity.

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