Hepatic Metabolic Derangements Triggered by Hyperthermia: An In Vitro Metabolomic Study

Far-infrared radiation alleviates steatohepatitis and fibrosis in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a disease that causes an abnormal accumulation of fat in the liver, triggering inflammation and fibrosis, the mechanism of which is not fully understood and for which there is a lack of specific drug therapy. Far-infrared radiation (FIR) has demonstrated evident therapeutic efficacy across various diseases, and novel nanomaterial graphene patches can emit it through electric heating. This study aimed to investigate the potential protective effects of FIR against MAFLD. Mice were fed with a MCD diet to mimic MAFLD progression, and histopathology analysis, biochemical analysis, RT-qPCR, and Western blotting analysis were performed to assess the effect of FIR on MAFLD in vivo. The effect of FIR treatment on MAFLD in vitro was investigated by biochemical analysis and gene expression profiling of hepatocytes. Mice subjected to the MCD diet and treated with FIR exhibited reduced hepatic lipid deposition, inflammation, fibrosis and liver damage. The therapeutic effect exerted by FIR in mice may be caused by the enhancement of AMPK phosphorylation and inhibition of the TGFβ1-SMAD2/3 pathway. Besides, FIR intervention alleviated MAFLD in hepatocytes in vitro and the results were verified by gene expression profiling. Our results revealed a promising potential of FIR as a novel therapeutic approach for MAFLD.

Hyperthermia-induced changes in liver physiology and metabolism: a rationale for hyperthermic machine perfusion

Liver transplantation is the standard treatment for end-stage liver disease. However, due to the ongoing disparity between supply and demand for optimal donor organs, there is increasing usage of extended criteria donor organs, including steatotic liver grafts. To mitigate the increased risks associated with extended criteria donor livers, ex situ oxygenated machine perfusion (MP) has received increasing attention in recent years as an emerging platform for dynamic preservation, reconditioning, and viability assessment to increase organ utilization. MP can be applied at different temperatures. During hypothermic MP (4-12°C), liver metabolism is reduced, while oxygenation restores the intracellular levels of adenosine triphosphate. The liver is quickly "recharged" to support metabolism when at normothermia (35-37°C) and to ameliorate the detrimental effects of ischemia/reperfusion injury during transplantation. During normothermia, MP can be applied to assess hepatocellular and cholangiocellular viability. MP at hyperthermic (>38°C) temperatures (HyMP), however, remains relatively understudied. The liver is an important component in the regulation of core body temperature and, as such, displays significant physiological and metabolic changes in response to different temperatures. Hyperthermia may promote vasodilation, increase aerobic metabolism and induce production of protective molecules such as heat shock proteins. Therefore, HyMP could provide an attractive reconditioning strategy for steatotic livers. In this review, we describe current literature on the physiological and metabolic effects of the liver at hyperthermia for human, rodents, and pigs and provide a rationale for using therapeutic HyMP during isolated liver machine perfusion to recondition extended criteria donor livers, including steatotic livers, before transplantation.

Effect of temperature on 3,4-Methylenedioxypyrovalerone (MDPV)-induced metabolome disruption in primary mouse hepatic cells

3,4-Methylenedioxypyrovalerone (MDPV) is one of the most popular cathinone derivatives worldwide and has recently been associated with several intoxications and deaths, in which, similarly to amphetamines, hyperthermia appears to play a prominent role. However, there remains a huge information gap underlying the mechanisms associated with its hepatotoxicity, namely under hyperthermic conditions. Here, we use a sensitive untargeted metabolomic approach based on gas chromatography-mass spectrometry (GC-MS) to investigate the effect of subtoxic and toxic concentrations of MDPV on the metabolic profile of primary mouse hepatocytes (PMH), under normothermic and hyperthermic conditions. For this purpose, hepatocytes were exposed to increasing concentrations of MDPV (LC₀₁, LC₁₀ and LC₃₀) for 24 h, at 37 °C or 40.5 °C, and alterations on both intracellular metabolome and extracellular volatilome were evaluated. Multivariate analysis showed a clear separation between MDPV exposed cells and control cells in normothermic conditions, even at subtoxic concentrations (LC₀₁ and LC₁₀). In normothermia, there was a significant dysregulation of pathways associated with ascorbate metabolism, tricarboxylic acid (TCA) cycle and pyruvate metabolism. These metabolic changes were significantly increased at 40.5 °C, and several other pathways appear to be affected with the evolution of toxicity caused by MDPV under hyperthermic conditions, namely aspartate and glutamate metabolism, phenylalanine and tyrosine biosynthesis, aminoacyl-tRNA biosynthesis, butanoate metabolism, among others. Overall, our findings provide novel insights into the mechanism of hepatotoxicity triggered by MDPV and highlight the higher risks that may occur under hyperthermic conditions.

3,4-Methylenedioxymethamphetamine Hepatotoxicity under the Heat Stress Condition: Novel Insights from in Vitro Metabolomic Studies

Hyperthermia has been extensively reported as a life-threatening consequence of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) abuse. In this work, we used a sensitive untargeted metabolomic approach based on gas chromatography-mass spectrometry to evaluate the impact of hyperthermia on the hepatic metabolic changes caused by MDMA. For this purpose, primary mouse hepatocytes were exposed to subtoxic (LC₀₁ and LC₁₀) and toxic (LC₃₀) concentrations of MDMA for 24 h, at 37 or 40.5 °C (simulating body temperature increase after MDMA consumption), and alterations on both intracellular metabolome and extracellular volatilome were evaluated. Multivariate analysis showed that metabolic patterns clearly discriminate MDMA treated cells from control cells, both in normothermic and hyperthermic conditions. The metabolic signature was found to be largely common to MDMA subtoxic and toxic concentrations, although with evident differences in the magnitude of response, with metabolic changes significantly more pronounced at 40.5 °C. Discriminant metabolites associated with MDMA-induced hepatotoxicity are mostly involved in the amino acid metabolism, aminoacyl tRNA biosynthesis, glutathione metabolism, tricarboxylic acid cycle, and pyruvate metabolism. Moreover, our metabolomic findings were corroborated by classical toxicity parameters, demonstrating the high sensitivity of this omic approach to assess molecular-level effects. Overall, this study indicates that MDMA triggers significant metabolic alterations on hepatic cells, even at low concentrations, that are clearly exacerbated at high temperatures. These findings provide new metabolic pieces to solve the puzzle of MDMA's hepatotoxicity mechanism and emphasize the increased risks of MDMA abuse due to the thermogenic action of the drug.