Inflammasome Activation as a Key Driver of Acetaminophen-induced Hepatotoxicity: Mechanisms and Emerging Therapeutics

Acetaminophen (APAP) is one of the most commonly used analgesic and antipyretic medications and is generally considered safe at therapeutic doses. However, overdose remains a leading cause of acute liver failure, primarily characterized by centrilobular (zone 3) hepatic necrosis, oxidative stress, mitochondrial dysfunction, and sterile inflammation. The hepatotoxic effects of APAP are localized to the centrilobular region, where cytochrome P450 2E1 is highly expressed. Cytochrome P450 2E1 catalyzes the conversion of APAP to a toxic metabolite, N-acetyl-p-benzoquinone imine. During overdose, the liver’s detoxification capacity is overwhelmed and excess N-acetyl-p-benzoquinone imine binds to cellular proteins, initiating oxidative stress and mitochondrial injury that culminate in hepatocyte death. A central component of APAP-induced hepatotoxicity is the activation of innate immune responses, particularly via inflammasome pathways. Inflammasomes are cytosolic multiprotein complexes that detect cellular damage and trigger inflammation. Among these, the NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome plays a significant role in APAP-induced liver injury. Upon activation, the NLRP3 inflammasome promotes autocatalytic cleavage of procaspase-1 into its active form, caspase-1, which subsequently processes the pro-inflammatory cytokines pro-interleukin-1β and pro-interleukin-18 into their mature forms. These cytokines recruit additional immune cells and amplify liver inflammation, exacerbating tissue injury. Thus, the NLRP3 inflammasome serves as a key mechanistic link between the initial toxic insult and the ensuing inflammatory response in APAP hepatotoxicity. This review aimed to explore the molecular mechanisms underlying APAP-induced liver injury, particularly inflammasome activation, and evaluate the current and emerging therapeutic strategies.