Extracellular vesicles originating from steatotic hepatocytes promote
hepatic stellate cell senescence via AKT/mTOR signaling
Abstract
The prevalence of metabolic dysfunction-associated steatotic liver
disease (MASLD) is increasing rapidly due to the obesity epidemic. In
the inflammatory stages of MASLD (NASH), activation of hepatic stellate
cells (HSCs) leads to initiation and progression of liver fibrosis.
Extracellular vesicles (EVs) are released from all cell types and play
an important role in intercellular communication. However, the role of
EVs released from hepatocytes in the context of MASLD is largely
unknown. Therefore, the present study aimed to investigate the role of
EVs derived from both normal and steatotic (free fatty acid-treated)
hepatocytes on the phenotype of HSCs via the senescence pathway. Primary
rat hepatocytes were treated with free fatty acids (FFAs: oleic acid and
palmitic acid). EVs were collected by ultracentrifugation. EVs markers
and HSCs activation and senescence markers were assessed by Western
blot, qPCR and cytochemistry. Reactive oxygen species (ROS) production
was assessed by fluorescence assay. RNA profiles of EVs were evaluated
by sequencing. We found that EVs from hepatocytes treated with FFAs
(FFA-EVs) inhibit collagen type 1 and α-smooth muscle actin expression,
increase the production of ROS and the expression of senescence markers
(IL-6, IL-1β, p21 and senescence-associated β-galactosidase activity) in
early activating HSCs via the AKT-mTOR pathway. Sequencing showed
differentially enriched RNA species between the EVs groups. In
conclusion, EVs from FFA-treated hepatocytes inhibit HSC activation by
inducing senescence via the AKT-mTOR signaling pathway. Determining the
components in EVs that induce HSC senescence may lead to the
identification of novel targets for the intervention of MASLD.