Although some clinical studies have reported increased mitochondrial respiration in patients with fatty liver and early non‐alcoholic steatohepatitis (NASH), there is a lack of in vitro models of non‐alcoholic fatty liver disease (NAFLD) with similar findings. Despite being the most commonly used immortalized cell line for in vitro models of NAFLD, HepG2 cells exposed to free fatty acids (FFAs) exhibit a decreased mitochondrial respiration. On the other hand, the use of HepaRG cells to study mitochondrial respiratory changes following exposure to FFAs has not yet been fully explored. Therefore, the present study aimed to assess cellular energy metabolism, particularly mitochondrial respiration, and lipotoxicity in FFA‐treated HepaRG and HepG2 cells. HepaRG and HepG2 cells were exposed to FFAs, followed by comparative analyses that examained cellular metabolism, mitochondrial respiratory enzyme activities, mitochondrial morphology, lipotoxicity, the mRNA expression of selected genes and triacylglycerol (TAG) accumulation. FFAs stimulated mitochondrial respiration and glycolysis in HepaRG cells, but not in HepG2 cells. Stimulated complex I, II‐driven respiration and β‐oxidation were linked to increased complex I and II activities in FFA‐treated HepaRG cells, but not in FFA‐treated HepG2 cells. Exposure to FFAs disrupted mitochondrial morphology in both HepaRG and HepG2 cells. Lipotoxicity was induced to a greater extent in FFA‐treated HepaRG cells than in FFA‐treated HepG2 cells. TAG accumulation was less prominent in HepaRG cells than in HepG2 cells. On the whole, the present study demonstrates that stimulated mitochondrial respiration is associated with lipotoxicity in FFA‐treated HepaRG cells, but not in FFA‐treated HepG2 cells. These findings suggest that HepaRG cells are more suitable for assessing mitochondrial respiratory adaptations in the developed in vitro model of early‐stage NASH.
- MeSH
- buněčné linie MeSH
- buňky Hep G2 MeSH
- dýchání MeSH
- kyseliny mastné neesterifikované MeSH
- lidé MeSH
- mitochondrie MeSH
- nealkoholová steatóza jater * MeSH
- triglyceridy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Melanins belong to a group of pigments of different structure and origin. They can be produced synthetically or isolated from living organisms. A number of studies have reported testing of various melanins in neurological studies providing different outcomes. Because the structure of melanins can have an effect on obtained results in cell toxicity studies, we present here our original study which aimed to compare the biological effects of bacterial melanin (biotechnologically obtained from B. thuringiensis) with that of synthetic melanin in neuroblastoma cells. Both melanins were structurally characterized in detail. After melanin treatment (0-200 μg/mL), cell viability, glutathione levels, cell morphology and respiration were assessed in SH-SY5Y cells. The structural analysis showed that bacterial melanin is more hydrophilic according to the presence of larger number of -OH moieties. After melanin treatment, we found that synthetic melanin at similar dosage caused always larger cell impairment compared to bacterial melanin. In addition, more severe toxic effect of synthetic melanin was found in mitochondria. In general, we conclude that more hydrophilic, bacterial melanin induced lower toxicity in neuroblastoma cells in comparison to synthetic melanin. Our findings can be useable for neuroscientific studies estimating the potential use for study of neuroprotection, neuromodulation or neurotoxicity.
- MeSH
- Bacteria MeSH
- glutathion MeSH
- lidé MeSH
- melaniny * MeSH
- mitochondrie MeSH
- neuroblastom * farmakoterapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
CONTEXT: Monoestolides belonging to the fatty acid-hydroxy fatty acid (FAHFA) family have recently emerged as promising insulin sensitizers. OBJECTIVE: To investigate and compare impact of two selected FAHFA isomers, namely 9-hexadecanoyloxy-octadecanoic acid [9-PAHSA] and 9-(9Z-octadecenoyloxy)-octadecanoic acid [9-OAHSA], on intact livers in C57BL/6J mice. MATERIALS AND METHODS: Short-term in vivo study with intragastric gavage of 13 mg/kg of substances. Morphological, biochemical and high-resolution respirometric assessment of plasma and liver tissue or homogenates thereof. RESULTS: The 9-OAHSA-gavaged mice had the highest final total body weight, the lowest free fatty acid circulating levels and the highest plasma activities of both ALT and AST. No significant changes of ambient glycaemia were found, however 9-PAHSA-gavaged mice tended to have lower glycaemia than other animals. Respirometry proved no substance-dependent differences. DISCUSSION AND CONCLUSION: 9-PAHSA was more metabolically beneficial and less hepatotoxic than 9-OAHSA. Bioenergetic machinery of liver homogenates seemed unaffected at our FAHFA dose.
Mitochondrial substrate flux is a distinguishing characteristic of each cell type, and changes in its components such as transporters, channels, or enzymes are involved in the pathogenesis of several diseases. Mitochondrial substrate flux can be studied using intact cells, permeabilized cells, or isolated mitochondria. Investigating intact cells encounters several problems due to simultaneous oxidation of different substrates. Besides, several cell types contain internal stores of different substrates that complicate results interpretation. Methods such as mitochondrial isolation or using permeabilizing agents are not easily reproducible. Isolating pure mitochondria with intact membranes in sufficient amounts from small samples is problematic. Using non-selective permeabilizers causes various degrees of unavoidable mitochondrial membrane damage. Recombinant perfringolysin O (rPFO) was offered as a more appropriate permeabilizer, thanks to its ability to selectively permeabilize plasma membrane without affecting mitochondrial integrity. When used in combination with microplate respirometry, it allows testing the flux of several mitochondrial substrates with enough replicates within one experiment while using a minimal number of cells. In this work, the protocol describes a method to compare mitochondrial substrate flux of two different cellular phenotypes or genotypes and can be customized to test various mitochondrial substrates or inhibitors.
Mitochondria play an essential role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Previously, we found that succinate-activated respiration was the most affected mitochondrial parameter in mice with mild NAFLD. In this study, we focused on the role of succinate dehydrogenase (SDH) in NAFLD pathogenesis. To induce the progression of NAFLD to nonalcoholic steatohepatitis (NASH), C57BL/6J mice were fed a Western-style diet (WD) or control diet for 30 weeks. NAFLD severity was evaluated histologically and the expression of selected proteins and genes was assessed. Mitochondrial respiration was measured by high-resolution respirometry. Liver redox status was assessed using glutathione, malondialdehyde, and mitochondrial production of reactive oxygen species (ROS). Metabolomic analysis was performed by GC/MS. WD consumption for 30 weeks led to reduced succinate-activated respiration. We also observed decreased SDH activity, decreased expression of the SDH activator sirtuin 3, decreased gene expression of SDH subunits, and increased levels of hepatic succinate, an important signaling molecule. Succinate receptor 1 (SUCNR1) gene and protein expression were reduced in the livers of WD-fed mice. We did not observe signs of oxidative damage compared to the control group. The changes observed in WD-fed mice appear to be adaptive to prevent mitochondrial respiratory chain overload and massive ROS production.
- MeSH
- apoptóza MeSH
- biologické markery MeSH
- buněčné dýchání MeSH
- fibróza MeSH
- jaterní mitochondrie metabolismus MeSH
- kyselina jantarová metabolismus MeSH
- metabolom MeSH
- metabolomika metody MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- náchylnost k nemoci MeSH
- nealkoholová steatóza jater etiologie metabolismus patologie MeSH
- oxidace-redukce * MeSH
- oxidační stres * MeSH
- sukcinátdehydrogenasa metabolismus MeSH
- západní dieta * MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
