Lutein Attenuates Lipid Accumulation in Association with TFEB Nuclear Translocation and Autophagy–Lysosomal Responses in a Cellular Model of Hepatic Steatosis
TL;DR
Findings position the antioxidant lutein as a candidate natural compound whose lipid-lowering action is associated with TFEB nuclear translocation/activation and with the autophagy–lysosomal pathway, warranting further investigation in MASLD.
Abstract
Lutein is a dietary xanthophyll carotenoid valued for its antioxidant properties that has been shown to benefit liver health and reduce hepatic lipid accumulation; however, this lipid-lowering effect cannot be fully attributed to its antioxidant activity, and the underlying mechanism remains poorly understood. Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by excessive hepatic lipid accumulation, oxidative stress, and limited therapeutic options. Transcription factor EB (TFEB) coordinates the autophagy–lysosomal pathways involved in cellular lipid clearance, including lipophagy and lysosomal exocytosis, and is sensitive to the cellular redox state; however, whether the antioxidant lutein modulates TFEB-regulated lipid homeostasis remains unclear. HepG2 cells were exposed to free fatty acids (FFAs) to induce intracellular lipid accumulation and co-treated with lutein. TFEB localization and the expression of TFEB-related genes were assessed by immunofluorescence and qPCR, respectively. Immunofluorescence was also used to evaluate lipid droplet accumulation, LC3 content, and LAMP1 localization. Lipid droplet ultrastructure was analyzed by transmission electron microscopy, and extracellular triglyceride levels were measured as a functional readout of lipid extrusion. Lutein attenuated lipid droplet accumulation in FFA-treated cells, increased nuclear TFEB immunoreactivity, upregulated LC3 mRNA expression, and enhanced LC3 colocalization with lipid droplets. Chloroquine abolished the lipid-lowering effect of lutein, supporting an autophagy-dependent mechanism. In addition, lutein increased the abundance of LAMP1-positive compartments, while ultrastructural analysis and elevated extracellular triglyceride levels suggested enhanced lipid extrusion. These findings position the antioxidant lutein as a candidate natural compound whose lipid-lowering action is associated with TFEB nuclear translocation/activation and with the autophagy–lysosomal pathway, warranting further investigation in MASLD.