Abstract:

Objective To explore the interplay between MCT1-mediated lactate accumulation and ferroptosis in acute liver failure （ALF）. Methods An ALF mouse model and a hepatocyte injury model were established using lipopolysaccharide （LPS） in combination with D-galactosamine （D-GalN）. The mice were randomly assigned to three groups： a blank control group， an ALF model group， and an ALF + Liproxstatin-1 （Lip-1） treatment group. In vitro experiments included four groups： A blank control， a hepatocyte injury model， a lactate intervention， and an MCT1 overexpression group. Commercial kits were used to measure lactate levels in both mouse liver tissues and cell supernatants， as well as the contents of malondialdehyde （MDA）， ferrous ions （Fe²⁺）， and reduced glutathione （GSH） in liver tissue. Liver histopathology was evaluated using hematoxylin and eosin （HE） staining. Transmission electron microscopy was employed to assess mitochondrial ultrastructure in hepatocytes. Western blot （WB） analysis was performed to determine the protein expression levels of MCT1， glutathione peroxidase 4 （GPX4）， and acyl-CoA synthetase long-chain family member 4 （ACSL4） in both liver tissues and cultured cells. Real-time quantitative PCR and immunofluorescence assays were utilized to detect mRNA expression and fluorescence intensity of GPX4 and ACSL4， respectively. Results HE staining of liver tissue from the ALF mouse model revealed extensive hepatocyte necrosis and partial inflammatory cell infiltration. Both MCT1 and GPX4 protein expression were significantly downregulated （P < 0.001）， whereas ACSL4 protein expression was markedly upregulated （P < 0.000 1）， accompanied by a significant elevation in lactate levels （P < 0.001）. Transmission electron microscopy demonstrated reduced mitochondrial volume and disorganized cristae arrangement in hepatocytes. In contrast to the model group， histological analysis of liver tissue from ALF mice treated with an iron death inhibitor showed attenuated liver injury. GPX4 expression was restored （P < 0.05）， while ACSL4 expression was reduced （P < 0.001）. Levels of lactate， MDA， and Fe²⁺ in liver tissue were significantly lower （P < 0.001）， whereas GSH levels were significantly higher （P < 0.05）. In vitro experiments indicated that lactate treatment suppressed GPX4 expression in hepatocytes in a concentration-dependent manner while promoting ACSL4 expression （P < 0.05）. In the hepatocyte injury model group， MCT1 and GPX4 expression were downregulated， ACSL4 protein expression was upregulated （P < 0.05）， and lactate levels were significantly increased （P < 0.05）. However， MCT1 overexpression effectively reversed these alterations， resulting in increased GPX4 expression （P < 0.05） and decreased ACSL4 expression （P < 0.001）. Furthermore， immunofluorescence results revealed enhanced GPX4 fluorescence intensity （P < 0.001） and reduced ACSL4 signal intensity （P < 0.01）， along with a marked reduction in lactate levels in cell supernatants （P < 0.000 1）. Conclusions This study demonstrates that ferroptosis plays a critical role in cell death during ALF and is closely intertwined with lactate metabolism. MCT1 mitigates LPS/D-GalN-induced ferroptosis by facilitating lactate transport in hepatocytes， thereby reducing lactate accumulation. Conversely， inhibition of ferroptosis leads to decreased lactate levels， indicating a bidirectional 'lactate-ferroptosis' regulatory loop.

Key words: acute liver failure, ferroptosis, lactic acid accumulation, monocarboxylate transporter 1