Effect of thioltransferase on oxidative stress induced by high glucose and advanced glycation end products in human lens epithelial cells

AIM:To study the effect of thioltransferase(TTase)on oxidative stress in human lens epithelial cells(HLECs)induced by high glucose and advanced glycation end products(AGEs).METHODS:HLECs were treated with 35.5 mmol/L glucose or 1.5 mg/mL AGEs modified bovine serum albumin(AGEs-BSA)as the experimental groups,respectively.Cells were collected at the time point of 1,2,3,and 4 d.The TTase activity were measured accordingly.TTase mRNA levels were detected by quantitative reverse transcription polymerase chain response(qRT-RCR)and its protein level was detected by Western blot.The siRNA was used to knock down the expression of TTase.The activity of catalase(CAT)and superoxide dismutase(SOD),the content of reactive oxygen species(ROS)and the ratio of oxidized glutathione/total glutathione(GSSG/T-GSH)were assessed in different groups,respectively.RESULTS:The level of TTase mRNA gradually increased and reached the top at 2 d,then it decreased to the normal level at 4 d,and the TTase activity increased from 2 to 3 d in both high glucose and AGEs-BSA groups.The TTase expression elevated from 2 d in high glucose group,and it began to rise from 3 d in AGEs-BSA group.The activity of CAT and SOD showed a decrease and the content of ROS and the ratio of GSSG/T-GSH showed an increase in high glucose and AGEs-BSA group.These biochemical alterations were more prominent in the groups with TTase siRNA.CONCLUSION:High glucose and AGEs can increase ROS content in HLECs;therefore,it induces oxidative stress.This may result in the decreased GSH and increased GSSG content,impaired activity of SOD and CAT.The up-regulated TTase likely provides oxidation damage repair induced by high glucose and AGEs in the early stage.

Evaluation of antioxidants and argpyrimidine in normal and cataractous lenses in north Indian population

AIM： To assess the level of glutathione, thioltransferase, and argpyrimidine in nuclear and cortical cataractous lenses as well as in the clear lenses in the north Indian population.METHODS： Human cataractous lenses were collected from the patients who underwent extracapsular cataract extraction surgery; clear lenses were collected from the freshly donated eye bank eyes. Antioxidant molecules such as glutathione and thioltransferase enzyme activity were measured; simultaneously in these lenses a blue fluorophore argpyrimidine, an advanced glycation end（AGE） product level was assessed using high performance liquid chromatography（HPLC）.RESULTS： The protein concentration was found to be present at higher levels in the control lenses compared to cataract lenses. A significant decrease in the glutathione level was observed in the nuclear cataractous lenses compared to cortical cataractous（P=0.004） and clear lenses（P≤0.005）, but no significant change in the level of antioxidant enzyme thioltransferase was observed. Further, argpyrimidine a blue fluorophore（AGE） was found to be significantly higher in the nuclear cataract（P=0.013） compared to cortical cataract lenses.CONCLUSION： Antioxidants such as glutathione significantly decrease in age-related nuclear and cortical cataract and an AGE, argpyrimidine are present at significantly higher levels in nuclear cataract.