Effects of sodium arsenite exposure on activation and extracellular matrix secretion of human hepatic stellate cells

Objective To explore the effects of sodium arsenite (NaAsO2) exposure on the activation and extracellular matrix secretion of human hepatic stellate cells, and to provide a theoretical basis for the mechanism study of arsenic induced hepatic fibrosis. Methods Different doses of NaAsO2 (0.0, 0.1, 1.0, 10.0, 50.0, 100.0 μmol/L) were exposed to human hepatic stellate cell line (Lx-2) for 24, 48 and 72 huors. CCK-8 assay was used to measure cell viability and IC50 of NaAsO2 on Lx-2 was then calculated; According to IC50 results, 0.000, 1.875, 3.750, 7.500, and 15.000 μmol/L of NaAsO2 were exposed to Lx-2 cells for 24 hours, besides, 7.500 μmol/L of NaAsO2 was exposed to Lx-2 cells for 0, 12, 24, 48, and 72 hours, then collected cells and culture supernatant; HSC activation-related protein, including α-smooth muscle actin (α-SMA), and transforming growth factor-β1 (TGF-β1) expression levels were detected by Western blot analysis, the main extracellular matrix including laminin (LN) , hyaluronic acid (HA), collagen Ⅳ (COL-Ⅳ) and procollagen Ⅲ(P Ⅲ NP) secretion level was detected by Elisa assay. Results CCK-8 assay showed that the cell viability of Lx-2 cells were increased obviously at low doses (≤1.0 μmol/L) of arsenic exposure, especially at 48 and 72 h. In contrast, with the increasing doses of arsenic exposure, the survival rate of Lx-2 cell was decreased gradually, and the survival rate of the high-dose (50, 100 μmol/L) arsenic exposure group at 24, 48 and 72 h were significantly lower than 0.0 μmol/L group, P<0.05. The IC50 of NaAsO2 on Lx-2 cells at 24, 48, 72 h were calculated as 72.75, 48.19 and 29.95 μmol/L, respectively; The expression levels of HSC activation-related protein showed that, after treated with 1.875, 3.750, 7.500, 15.000 μmol/L NaAsO2 for 24 h, α-SMA and TGF-β1 protein level were higher than 0.000 μmol/L group. The increased expression of α-SMA and TGF-β1 protein were most significant in 7.500 μmol/L NaAsO2 group (P<0.05). In addition, the expression levels of α-SMA and TGF-β1 also showed a time-dependent increasing in Lx-2 cells after treated with 7.500 μmol/L NaAsO2 for 0, 12, 24, 48 and 72 h; Elisa assay showed that after treated with 1.875, 3.750, 7.500, 15.000 μmol/L NaAsO2 for 24 h, the secretion levels of HA, LN, COL-Ⅳ and PⅢNP were obvious higher than 0.000 μmol/L group (P<0.05). Moreover, the secretion levels of HA, LN, COL-Ⅳ and P Ⅲ NP also showed a time-dependent increased manner in Lx-2 cells after exposed to 7.500 μmol/L NaAsO2 for 0, 12, 24, 48 and 72 h (P<0.05). Conclusion NaAsO2 exposure to Lx-2 cells can upregulate the expression level of HSC activation-related proteins, induce its further activation, then increase ECM secretion level. Key words: Extracellular matrix; Liver; Liver fibrosis; Sodium arsenite; Hepatic stellate cell