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

Abstract

Background and aims: Liver toxicity is a well-documented and potentially fatal adverse complication of hyperthermia. However, the impact of hyperthermia on the hepatic metabolome has hitherto not been investigated. Methods: In this study, gas chromatography-mass spectrometry (GC-MS)-based metabolomics was applied to assess the in vitro metabolic response of primary mouse hepatocytes (PMH, n = 10) to a heat stress stimulus, i.e., after 24 h exposure to 40.5 °C. Metabolomic profiling of both intracellular metabolites and volatile metabolites in the extracellular medium of PMH was performed. Results: Multivariate analysis showed alterations in levels of 22 intra- and 59 extracellular metabolites, unveiling the capability of the metabolic pattern to discriminate cells exposed to heat stress from cells incubated at normothermic conditions (37 °C). Hyperthermia caused a considerable loss of cell viability that was accompanied by significant alterations in the tricarboxylic acid cycle, amino acids metabolism, urea cycle, glutamate metabolism, pentose phosphate pathway, and in the volatile signature associated with the lipid peroxidation process. Conclusion: These results provide novel insights into the mechanisms underlying hyperthermia-induced hepatocellular damage.

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

“…50,52,53 In parallel, glyoxal is also capable of inducing the production of formaldehyde, a volatile compound that quickly reacts with nucleophilic groups of cellular components, thereby inducing mutagenic and carcinogenic events and consequent cell death. 54 Increased levels of methylglyoxal and formaldehyde have already been observed in the extracellular profile of hepatic cells exposed to an extreme thermic stimulation, 21 which is in accordance with the exacerbation of the magnitude of response of these metabolites after MDMA exposure in high temperature settings.…”

“…It should be noted that the hyperthermia condition per se leads to a significant imbalance between hepatic prooxidant and antioxidant levels, favoring the production of the first, which makes cells more sensitive to cellular damage. 5,10,11 Accordingly, we recently demonstrated 21 alterations in the levels of metabolites involved in the TCA cycle, amino acids metabolism, glutamate metabolism, and pentose phosphate pathway triggered by hyperthermia in the same experimental conditions. Now, we extend our previous work in order to understand how the metabolic response triggered by MDMA is altered by increasing the temperature to hyperthermic conditions.…”

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

“…Additionally, natural killer cells from rat sinusoid washout, incubated at 41°C in vitro for 4 h, showed decreased cytotoxic activity due to a disruption of target cell binding (42). This can be directly attributed to increased cell membrane fluidity and instability, as mentioned previously (3,10). Liver sections from rats heated to 41.5°C in a heat chamber also showed pyknosis and nuclear fragmentation in Kupffer cells (16).…”

“…While some amount of hepatic injury is a common symptom of exertional heat stroke (Ͼ39°C), it is rare that the level of hepatocellular damage incurred results in death (13,26). Cellular damage may be caused as a result of cell membrane instability and dysfunction of mitochondria and protein transport and may decrease cell viability by 35% in isolated mouse hepatocytes after heat exposure to 40.5°C (3). While research into the effects of lower hyperthermic temperatures on specific hepatic cell types is scarce, mononuclear cells from the liver sinusoid in rats showed a decrease in cytotoxic activity when experiencing whole body hyperthermia at 40°C for 4 h, measured by clearance of an intravenously injected, labeled leukemia cell line (K562).…”

“…A temperature change from 37°C to 40.5°C resulted in profound changes to the metabolomic profile, including a decrease in TCA cycle components (fumarate, malate, and 2-ketogluterate), a change in levels of synthesis of various amino acids, and alterations to the urea cycle. These were shown to contribute directly to hyperthermia-induced hepatocyte damage (3).…”