| As a complex metabolic disorder, Diabetes Mellitus (DM) has becomethe third leading cause of death after cancer and cardiovascular disease.According to the estimation of World Health Organization, by2025, thenumber of global prevalence of diabetes will reach300million. The Type2Diabetes Control Guidelines (2010) of China has showed that diabetesincidence rate reached9.7percent, with more than92.4million patients.Moreover, the pre-diabetes that reached about15percent, with a total of morethan148million, which is much higher than the developed countries. Chroniccomplications of diabetes have become the main reason of disability orpremature death of diabetic patients. As one of the most common chroniccomplications, diabetic retinopathy (DR) caused more than10,000people ofblindness each year. Relative to other organizations, the retina tissue containsmore polyunsaturated fatty acids, which makes the highest intake of theoxygen molecules in the blood, and also the strongest oxidative stress.Therefore, retinal oxidative stress is more impressionable than otherorganizations. So some scholars have point out that the relationship of highblood sugar, balance of promote oxidation, antioxidant system and oxidativestress is the key pathogenesis on DR. As a pleiotropic transcriptional factor,nuclear factor-kappa B (NF-κB) has played an important role in cell survival,immunity and inflammation. In addition, NF-κB is not only sensitive to redoxreactions, but also an important regulator of antioxidant enzymes. Accordingto different cell types and diseases, NF-κB activation can be anti-apoptotic orinduce apoptosis. NF-κB activated by diabetes in the retina, whose capillarycells is considered to induce apoptosis. Intercellular adhesion molecule-1(ICAM-1), which is a membrane glycoprotein, can mediate cell adhesion. It plays an important role in immune responses, inflammation and apoptosis.With the exploration of oxidative stress and inflammation developed on DR,we believe that looking for more effective both anti-inflammatory andantioxidant drugs will become the new researchdirection of DR drugs.Objective: This study is to observe the invitro effect of high glucose onhuman retinal pigment epithelial (HRPE) cells. Then the HRPE cells wereintervened with both high glucose and the medicine of alpha-lipoic-acid(α-LA), in order to compare the changes between with or without α-LA of cellmorphology, cellular activities, oxidative stress Levels and the expression ofnuclear factor-kappaB (NF-κB), intercellular adhesion molecule-1(ICAM-1).Through this study we can provide an experimental evidence for an importantroles of oxidative stress and inflammation have played in the development ofdiabetic retinopathy (DR). At the same time, our study also went further toprobe into the protection mechanism of alpha-lipoic-acid for DR.Method:Human retinal pigment epithelial cells were cultured andrandomly divided into eight groups:⑴normal control group (glucose'sconcentration:5.56mmol/l);⑵high glucose group (glucose's concentration:30.00mmol/l);⑶hypertonic control group(osmotic pressure:30.00mmol/L);⑷h igh glucose+α-LA (10umol/l)group;⑸high glucose+α-LA (50umol/l)group;⑹h igh glucose+α-LA (100umol/l) group;⑺h igh glucose+α-LA (200umol/l) group;⑻high glucose+α-LA (300umol/l)group. They were exposedto experimental conditions for48hours, respectively, preserved samples fortesting at a later time. The cellular activities is detected by MTT; themalondialdehyde (MDA), glutathione (GSH) and superoxide (SOD) aremeasured by colorimetry; NF-κB is measured by Western Blot; ICAM-1ismeasured by ELISA.Results:1Compared to normal control group, after cultured by high glucose, theproliferation of HRPE cells was significantly inhibited (P<0.05), the MDA,ICAM-1levels were significantly increased(P<0.05), while SOD, GSH levelswere obviously reduced(P<0.05), and the expression of NF-κB was high(P <0.05); there was no significant difference between hypertonic control groupand normal control group(P>0.05).2Compared to the high glucose group, after intervented by α-LA, NF-κBexpression was reduced(P<0.05); except for10μmol/L group, the proliferationof HRPE cells were recovered(P<0.05), the MDA, ICAM-1levels weredecreased (P <0.05), SOD, GSH levels were increased (P <0.05).3Compared with any two groups intervented by α-LA, we found that, exceptfor100μmol/L,200μmol/L groups, the MDA levels of any two groups weredifferent(P<0.05). Compared to300μmol/L group, SOD activity weredifferent in50μmol L,100μmol L,200μmol L groups(P<0.05).There wereno difference of GSH levels between any two groups(P>0.05). The expressionof NF-κB in10μmol L group was different to100μmol L,200μmol L,300μmol L groups, which in300μmol L group was different to50μmol L,100μmol L groups(P<0.05). The ICAM-1level in300μmol L groups wasdifferent to50μmol L,100μmol L,200μmol L groups, which in200μmol Lwas different to50μmol L,100μmol L groups (P<0.05). Therefore broadlyspeaking, the effect of α-LA is dose-dependent.Conclusion:1High glucose can decrease HRPE cells' proliferation, cause the levels ofSOD and GSH to decrease, MDA as well as NF-κB and ICAM-1increasedsignificantly. It is prompted that high glucose damages HRPE cells throughthe oxidative stress, NF-κB and ICAM-1, which may be associated with thepathogenesis of DR.2A certain concentration of alpha-lipoic-acid can reduce the impact of highglucose on the proliferation and MDA of HRPE cells, increase the SOD andGSH, knock down the expression of NF-κB, ICAM-1, and then improve cellfunction, reduce cell damage. It is prompted α-LA may be protect HRPE cellsby this way, and has the effect to prevention and treatment of DR.3In our study, except for NF-κB, α-LA can not play a protective role until itsconcentration reached50μmol/L or more. From50μmol/L, with theconcentration raising, the protection effect of α-LA is increasing. It is prompted that α-LA must reach a certain concentration to be effective, and theprotection effect on HRPE cells of α-LA is dose-dependent. |
PDF Full Text Request