Studies on the mechanism of inhibitory effect of lithium chloride on the proliferation of human Tenon capsule fibroblasts

Objective

To investigate the effect of lithium chloride (LiCl) on the gap junctional intercellular communication (GJIC) in human Tenon capsule fibroblasts (HTFs) and its underlying mechanism.

Methods

The Tenon capsule tissue of a patient who underwent strabismus surgery in Dezhou People’s Hospital in April 2019 was collected and cut into tissue blocks of dimensions 1 mm×1 mm×1 mm.Primary culture and subculture were carried out, and the 4th-generation HTFs were taken for experiment.HTFs were divided into the control group and LiCl treatment group and were cultured with cell medium without or with 80 mmol/L LiCl for another 48 hours according to grouping.The cell scratch and dye labeling technique were used to label the coupling index and evaluate the GJIC function.The expression and localization of Cx43 in HTFs were detected by immunofluorescence staining.The expression levels of Cx43 mRNA and protein were detected by real-time fluorescence quantitative PCR and Western blot, respectively.The study protocol was approved by an Ethics Committee of Dezhou People’s Hospital (No.2019-023). Written informed consent was obtained from the subject.

Results

The cultured spindle-shaped HTFs grew adhering to the wall showing radial monolayer or vortexlike, and the cytoplasm was vimentin positive.Results of dye tracer experiment of cell scratch showed that the cell coupling index of LiCl treatment group was 9.04±0.53, which was significantly higher than 4.94±0.39 of the control group (t=-18.79, P<0.01). Immunofluorescence staining showed that the Cx43 fluorescence was dotted in the cell membrane between adjacent cells in the control group, and Cx43 staining was obviously enhanced in the LiCl treatment group.The results of real-time fluorescence quantitative PCR showed that with relative expression level of Cx43 mRNA in the control group set to 1, the relative expression level of Cx43 in the LiCl treatment group was significantly increased to 1.97±0.23, showing a statistical significance between them (t=-14.426, P<0.01). Western blot showed that the relative expression level of Cx43 protein was 0.871±0.057 in the LiCl treatment group, which was significantly higher than 0.446±0.028 in the control group (t=-11.682, P<0.01).

Conclusions

LiCl can enhance the GJIC function between HTFs by upregulating the expression levels of Cx43 mRNA and protein, suggesting that the enhanced GJIC function by LiCl may be one of the mechanisms of its inhibition on HTFs proliferation.

Lithium chloride; Gap junction; Human Tenon capsule fibroblasts; Glaucoma