Moderate Hypothermia Effectively Alleviates Acetaminophen-Induced Liver Injury With Prolonged Action Beyond Cooling

Abstract

Acetaminophen (APAP) overdose accounts for the highest incidence of acute liver failure, despite the availability of an antidote i.e. N-acetylcysteine. This calls for alternative strategies to manage APAP-induced liver injury (AILI). Therapeutic hypothermia has been explored in past studies for hepatoprotection, but these phenomenal reports lack clarification of its optimal window for application, and mechanistic effects in specific AILI. Hence, we conducted an in vitro study with transforming growth factor-α transgenic mouse hepatocytes cell line, TAMH, and human liver hepatocytes cell line, L-02, where cells were conditioned with deep (25°C) or moderate (32°C) hypothermia before, during or after APAP toxicity. Cell viability was evaluated as a hallmark of cytoprotection, along with cell death. Simultaneously, cold shock proteins (CSPs) and heat shock proteins expressions were monitored; key liver functions including drug-metabolizing ability and hepatic clearance were also investigated. Herein, we demonstrated significant hepatoprotection with 24-hour moderate hypothermic conditioning during AILI and this effect sustained for at least 24 hours of rewarming. Such liver preservation was associated with a CSP—RNA-binding motif protein 3 (RBM3) as its knockdown promptly abolished the cytoprotective effects of hypothermia. With mild and reversible liver perturbations, hypothermic therapy appears promising and its RBM3 involvement deserves future exploration.

In vivo demonstration of a novel non-invasive model for inducing localized hypothermia to ameliorate hepatotoxicity

“…Previous studies have characterized the effects of hypothermia on AILI in vitro 1 , 2 . With this established understanding, we hoped to translate the concept of hypothermic treatment into a clinically actionable therapy-one which achieved hepatoprotection with minimal invasiveness and adverse outcomes.…”

“…We have previously reported on the potential of using moderate hypothermia (32 °C) to ameliorate acetaminophen-induced liver injury (AILI) in vitro 1 and presented various mechanistic insights on the effect of hypothermia in AILI 2 . Notwithstanding its demonstrated efficacy, the conduct of systemic hypothermia in clinical settings drew skepticism as this could incur non-specific adverse effects such as a slowdown in overall metabolism 3 .…”

“…Furthermore, Wang et al . reported an upregulation of cold shock protein (CSP) expression in the liver following CIC exposure 6 , where CSP was previously shown to play an imperative role in conferring cytoprotection 1 . Collectively, all these reports present intermittent cooling as a viable approach for achieving therapeutic hypothermia in the toxic liver.…”

“…Hence, we have attempted to improvise the concept of CIC by applying three primary changes. Firstly, moderate hypothermic conditioning would be performed concurrently with drug-induced liver injury (DILI), since liver preservative effects were evident in the past study when hepatocytes were conditioned with moderate hypothermia 1 . This averts potential destructive effects associated with severe hypothermia (< 30 °C).…”

“…With this model of a novel, non-invasive pulsed cooling modality, we sought to validate its feasibility and efficacy for the amelioration of acute DILI through an in vivo mouse study. Acetaminophen (APAP) was used as the model toxicant in accordance with past studies of hypothermic conditioning in AILI in vitro 1 , 2 . Herein, the study first involved a pilot phase to evaluate the feasibility of attaining regional cooling close to the liver.…”