Lithium prevents glucocorticoid-induced chondrocyte autophagy: An in vitro study

Glucocorticoids can induce chondrocyte autophagy. Lithium is a classical regulator of autophagy. The present study aimed to determine whether lithium can prevent glucocorticoid-induced chondrocyte autophagy by regulating the PI3K/AKT/mTOR signaling pathway. For this purpose, rat and human chondrocytes were treated with dexamethasone (200 mu M) or dexamethasone (200 mu M) combined with lithium chloride at various concentrations (0.01, 0.1, 1 and 10 mM). CYTO-ID (R) autophagy fluorescence staining and transmission electron microscopy were used to detect the levels of autophagy in the chondrocytes. Reverse transcription-quantitative PCR and western blot analysis were used to measure the expression levels of the autophagy marker, LC3B and the autophagy regulatory signaling pathway (PI3K/AKT/mTOR signaling pathways) markers, AKT and mTOR. The viability of chondrocytes was measured using the Cell Counting Kit-8 assay. It was found that compared with that in the control group, dexamethasone induced the autophagy of chondrocytes, decreased the expression levels of AKT and mTOR, and reduced cell viability. Compared with the treatment with dexamethasone alone, lithium chloride (10 mM) + dexamethasone reduced the autophagy levels, increased the expression level of AKT and mTOR, and increased cell viability. In conclusion, the present study demonstrated that lithium can prevent glucocorticoid-induced autophagy by activating the PI3K/AKT/mTOR signaling pathway and preventing the glucocorticoid-induced decrease in chondrocyte viability.