Effects of dexamethasone on expression of nuclear factor kappa B/inhibitor kappa B alpha and apoptosis of lens epithelial cells / 中华实验眼科杂志

ABSTRACT

Background Researches demonstrated that the long-term application of glucocorticoids can induce cataract. However, its molecular mechanism is unclear. Objective Present study was to investigate the effects of dexamethasone on the regulation of nuclear factor kappa B( NF-κB)/ inhibitor kappa B alpha( IκBα) line on human lens epithelial cells (LECs) and the LECs apoptosis. Methods Human LECs line(HLE2B3) were cultured and passaged in DMEM containing 20% fetal bovine serum and treated by different concentrations of dexamethasone(0. 01,0. 1,1,10,100 μmol/L) for 24,36 and 48 hours respectively. The LECs cultured in free-serum DMEM without dexamethasone were as blank control group. The expressions of IκBo in the LECs were examined by reverse transcription polymerase chain reaction ( RT-PCR) and Western blot, and the expressions of NF-κB neucleoprotein in LECs were detected by Western blot after exposure to dexamethasone. The apoptosis rate of LECs was determined by flow cytometer. Results Agarose gel electrophoresis showed that the amplified gene fragment was coincident to designed one. The expressing level of NF-κB neucleoprotein in LECs was significantly lowed with the increase of dexamethasone concentration ( F = 36. 077 , P = 0. 004 ) , and that of IkBo was evidently ascended ( F = 35. 741 ,P = 0. 002). In the same concentration of dexamethasone group,the expression of NF-κB in LECs showed the considerable alteration in different duration after treated of dexamethasone with the lowest expressing level in 36 hours, and significant differences were found in the expressing level between 24 hours and 36 hours ( P = 0. 002) and between 24 hours and 48 hours (P = 0. 01). The differences of expression of IκBá in LECs appeared the same pattern to NF-κB neucleoprotein. Flow cytometry showed that the apoptosis rate of LECs was obviously enhanced after action of dexamethasone in a dose-dependent manner, showing a significant difference among different groups ( F = 73. 261, P = 0.001). Conclusion It is implied that dexamethasone results in the pathogenesis and development of glucocorticoid cataract by up-regulating the expression of IκBα in LECs and suppressing the activity of NF-κB and herein induce the apoptosis of LECs at concentration-and time-dependent manner. This might be one of cellular and biological mechanisms of glucocorticoid cataract formation.