Research On Protection Of Curcumin From Injury Of Human Bronchial Epithelial Cells Caused By Cigarette Smoke Extract

Objective: Exploring the anti-oxidation effects of Curcumin and Keap1/Nrf2 pathway on the injury of human bronchial epithelial cells(HBEC)by cigarette smoke extract(CSE).Methods: While culturing 16 HBEC cells in vitro and using CSE as stimulus,the author tries to represent the oxidation/anti-oxidation imbalance of COPD.By applying curcumin to inhibit the process,the author intends to explore the protective effect it has on oxidative damage of epithelial cells.Effects of CSE(1%,2%,4%,6%,8%,10%)and curcumin(0 ?mol/l,3 ?mol/l,5 ?mol/l,7 ?mol/l,10 ?mol/l)on cell proliferation at different times(24h,48 h,72h)are monitored by CCK-8.The optimal concentration and time of curcumin and CSE acting on 16 HBEC are respectively selected.RT-PCR is used to detect the transcription level of Keap1 mRNA,Nrf2 mRNA,HO-1 mRNA and NQO1 mRNA and Western Blotting is used to detect the protein expression of Keap1,Nrf2,HO-1,NQO1.Results: CSE can inhibit the proliferation of 16 HBEC cells(P<0.05).The increase of time and concentration turns out to be proportional to how CSE inhibits the proliferation of 16HBEC(P<0.05).48 hours after CSE being applied to 16 HBEC,the IC50 concentration(concentration for 50% inhibition of cells)is calculated to be2.21% and the number 2% is,thereafter,used as the intervention concentration of CSE in subsequent experiments.48 hours after curcumin being applied to 16 HBEC when the concentration is less than 5?mol/l,there is no significant proliferation of16 HBEC.When the concentration exceeds 7?mol/l,curcumin does inhibit 16 HBEC from proliferating(P<0.01).Thus,5?mol/l is set as the intervention concentration in the follow-up experiments.After 48 hours of treatment with 2% CSE,the morphology of 16 HBEC is changed,leading to cell damage,which is alleviated through a 12-hour pretreatment with 5 ?mol/l Cur and a stimulus with 2% CSE.Curcumin can relieve16 HBEC damage caused by CSE.With the stimulus of CSE,the expression of Keap1 mRNA increases and that of Nrf2 m RNA,HO-1 mRNA and NQO1 mRNA decreases.As curcumin curbs the expression of Keap1 mRNA,it improves that of Nrf2 m RNA and the downstream expression of HO-1 mRNA and NQO1 mRNA(P<0.05).With the stimulus of CSE,the protein expression of Keap1 increases,which results in the down-regulation of Nrf2 and its downstream HO-1 and NQO1 protein expression.While Cur inhibits the expression of Keap1 protein,it enhances the expression of Nrf2 and its downstream HO-1 and NQO1 protein.Conclusion: CSE doe sinhibit the proliferation of 16 HBEC and a positive correlation exists between it with the concentration and time.By activating the Keap1/Nrf2 pathway,curcumin inhibits CSE-induced oxidative damage in human bronchial epithelial cells.