Oxidative Stress-induced TRPV2 Expression Increase Involves In Diabetic Cataract And Apoptosis Of Lens Epithelial Cells In A High-glucose Environment

Number of diabetic patients is on the rise worldwide and diabetes is expected to affect425 million people by 2045.Diabetes is a risk factor for the development of cataracts.The incidence of cataracts in people with high blood glucose is 2-5 times that of the general population,and the onset time is earlier and the progression is faster.At present,surgery is the only way to treat cataract,but intraocular inflammation caused by surgery may become the cause of aggravating diabetic retinopathy,and increased vascular permeability after surgery may also rapidly worsen diabetic macular edema.As a serious complication of diabetes,cataract is one of the leading causes of blindness in the world,which has a great impact on the global medical and health undertakings and economy.However,the pathogenesis of cataract aggravated by diabetes is still unclear.The concentration of calcium(Ca²⁺)and reactive oxygen species（ROS）in the lens increases in long-term hyperglycemia.The number of lens epithelial cells decreases with the progression of diabetic cataract,and the apoptosis of lens epithelial cells plays a key role in the development of cataract.As a classical signaling molecule,Ca²⁺participates in many cellular signal transduction pathways and regulates cell activity in response to various internal and external stimuli,including cell contraction,proliferation,differentiation and apoptosis.Changes in cellular Ca²⁺signal transduction and/or Ca²⁺homeostasis can disrupt physiological processes leading to pathological outcomes.Although Ca²⁺may be involved in apoptosis,the specific role of Ca²⁺homeostasis dysfunction and its associated signal transduction in diabetic cataract remains unclear.We investigated the potential role of transient receptor potential vanilloid 2（TRPV2）in diabetic cataract,TRPV2 is a membrane protein that acts as a non-selective cation channel that permeates Ca²⁺and helps maintain Ca²⁺homeostasis in mammalian tissues and cells.Objective:To investigate whether ROS affects the expression and function of TRPV2channel protein,and whether TRPV2 promotes the occurrence and development of diabetic cataract by affecting the apoptosis of lens epithelial cells in diabetic cataract and high glucose environment.Methods:The epithelial tissues of lens capsule were collected from patients with diabetic cataract and senile cataract,and the expression of TRPV2 was detected by immunohistochemistry.HLEpi Cs and primary cultured rat lens epithelial cells were cultured in normal glucose（NG 5.6 m M）and high glucose（HG 25.6 m M）medium for1,3,5 and 7 days,respectively.Western blotting was used to detect differences in TRPV2 and apoptosis related proteins（Bcl-2,Bax,and cleaved caspase-3）expression levels in different groups.TUNEL was used to compare the differences of apoptosis in different groups.Ca²⁺imaging detects intracellular Ca²⁺concentration([Ca²⁺]_i)levels in a high-glucose environment.Results:Immunohistochemical and Western blotting analysis showed that the expression level of TRPV2 was significantly increased in the lens epithelial cells of diabetic cataract patients compared with senile cataract,as well as in human lens epithelial cells（HLEpi Cs）and primary rat lens epithelial cells cultured under high glucose conditions.The increase of[Ca²⁺]_iinduced by TRPV2 channel agonist2-aminoethyldiphenyl borate（2-APB）was significantly higher in HLEpi Cs and primary rat lens epithelial cells cultured in high glucose medium than in normal glucose cultured cells.This enhancement was blocked by TRPV2 non-specific inhibitor Ruthenium red（RR）and TRPV2 specific small interference（si）RNA transfection.Apoptosis of HLEpi Cs and primary cultured rat lens epithelial cells was significantly increased after7 days of high glucose culture,and apoptosis was inhibited by transfection of TRPV2-specific si RNA.In addition,ROS inhibitors significantly inhibit ROS-induced TRPV2-mediated Ca²⁺signaling and apoptosis under high glucose conditions.Conclusions:These findings suggest the mechanism by which high glucose upregulates TRPV2 protein through oxidative stress and induces the apoptosis of lens epithelial cells.It also provides a potential target for further study of new therapeutic options for diabetes-related cataract.