Cellular and molecular effects of Baccharis dracunculifolia D.C. and Plectranthus barbatus Andrews medicinal plant extracts on retinoid metabolism in the human hepatic stellate cell LX-2

Salvianolic acid B blocks hepatic stellate cell activation via FGF19/FGFR4 signaling

INTRODUCTION AND OBJECTIVES

The activation of hepatic stellate cells (HSCs) is the main cause of liver fibrosis. The beneficial effects of fibroblast growth factor (FGF) 19 on liver fibrosis were recently reported. The S. miltiorrhiza as well as S. miltiorrhiza derived bioactive chemical components has shown prominent antifibrotic effects in liver fibrosis but the mechanism is still not fully understood. We aimed to investigate the bioactive compounds derived from S. miltiorrhiza which exerts antifibrotic effects in HSCs via regulating FGF19.

MATERIALS AND METHODS

FGF19 level in culture media was determined by enzyme-linked immunosorbent assay. Cell proliferation was measured by Cell Counting Kit-8 assay. Further, mRNA and protein expressions were assessed by quantitative polymerase chain reaction and western blotting, respectively. Knocking down of FGF receptor 4 (FGFR4) by transfection with siRNA was used to confirm the role of FGF19/FGFR4 signaling.

RESULTS

Using the human HSC cell line LX-2, we screened several natural products and found that bioactive compounds isolated from Salvia miltiorrhiza, particularly salvianolic acid B, strongly upregulated FGF19 secretion by LX-2 cells. We further showed that salvianolic acid B inhibited lipopolysaccharide (LPS)-induced HSC proliferation and activation. LPS treatment may also reduce the mRNA and protein levels of FGF19 and its receptor FGFR4. Salvianolic acid B treatment restored the impaired expressions of FGF19 and FGFR4. Finally, FGFR4 knockdown abolished the antifibrotic effects of salvianolic acid B in the LPS-induced HSC activation model.

CONCLUSIONS

Salvianolic acid B prevented LPS-induced HSC proliferation and activation by enhancing antifibrotic FGF19/FGFR4 signaling.

Cellular and molecular effects of silymarin on the transdifferentiation processes of LX-2 cells and its connection with lipid metabolism

Fibrosis process in the liver is a clinical condition established in response to chronic lesions and may be reversible in many situations. In this process, hepatic stellate cells (HSCs) activate and produce extracellular matrix compounds. During fibrosis, the lipid metabolism is also altered and contributes to the transdifferentiation of the HSCs. Thus, controlling lipid metabolism in HSCs is suggested as a method to control or reverse the fibrotic condition. In the search for therapies that modulate lipid metabolism and treat liver diseases, silymarin has been identified as a relevant natural compound to treat liver pathologies. The present study aimed to evaluate the cellular and molecular effects of silymarin in the transdifferentiation process of HSCs (LX-2) from activated phenotype to a more quiesced-like cells , also focusing on understanding the modulatory effects of silymarin on lipid metabolism of HSCs. In our analyses, 100 µM of silymarin reduced the synthesis of actin filaments in activated cells, the synthesis of the protein level of α-SMA, and other pro-fibrotic factors such as CTGF and PFGF. The concentration of 150 µM silymarin did not reverse the activation aspects of LX-2 cells. However, both evaluated concentrations of the natural compound protected the cells from the negative effects of dimethyl sulfoxide (DMSO). Furthermore, we evaluated lipid-related molecules correlated to the transdifferentiation process of LX-2, and 100 µM of silymarin demonstrated to control molecules associated with lipid metabolism such as FASN, MLYCD, ACSL4, CPTs, among others. In contrast, cellular incubation with 150 µM of silymarin increased the synthesis of long-chain fatty acids and triglycerides, regarding the higher presence of DMSO (v/v) in the solvent. In conclusion, silymarin acts as a hepatoprotective agent and modulates the pro-fibrogenic stimuli of LX-2 cells, whose effects depend on stress levels in the cellular environment.