Effect Of Ferulic Acid On Radiation-induced Skin Injury

Objective:Radiation-induced skin injury universally appears in radiotherapy,nuclear leakage and nuclear safety accidents.Owing to the latency,procrastination,repeatability and refractory nature of the damage,people are full of concerns about the use of nuclear energy.Therefore,it is of great practical significance to establish an effective radiation-induced skin injury model and research the mechanism of its occurrence and development.There is a lack of effective drugs for radiation-induced skin injury.We found that ferulic acid（FA）is a kind of phenolic acid substance,generally existing in plants.In pharmacological research,it has many effects,such as anti-inflammatory,anti-oxidation,anti-thrombosis,analgesia,anti-radiation and other impacts,so it has great potential in the treatment of radiation-induced skin injury.In this study,the mechanism and the appropriate dosage form of ferulic acid in the treatment of radiation-induced skin injury were explored through the establishment of cell and animal models of radiation-induced skin injury.Methods:（1）Ha Ca T cells were irradiated with a single dose of ⁶⁰Coγ-ray（radiation source was 3m away from the cells and the dose rate was100.68 c Gy/min）.The cell activity was detected by CCK-8 method;the vitality of superoxide dismutase（SOD）was tested by water soluble tetrazolium salt（WST）staining method;malondialdehyde（MDA）was determined by thiobarbituric acid（TBA）method;the apoptosis rate was monitored by flow cytometry;the apoptosis and inflammation related proteins were measured by Western blot.Studying the damage and mechanism of Ha Ca T cells induced by different absorbed doses of ⁶⁰Coγ-ray,so as to establish a cell model of radiation-induced skin damage,it lays a foundation for the study of the occurrence and development of radiation-induced skin damage,and the research and development of anti-radiation drugs.（2）Ha Ca T cells were treated with different doses of ferulic acid processing.CCK-8 method was used to detect the survival rate of Ha Ca T cells to determine drug concentration;water soluble tetrazolium salt（WST）staining method was used to determine the activity of superoxide dismutase（SOD）;flow cytometry instrument was used to monitor the changes of reactive oxygen species（ROS）,enzyme linked immunosorbent assay（ELISA）and Western blot technique were used to detect the expression of NLRP3 inflammasome corpuscle,Caspase-1,IL-1βexpressed in Ha Ca T cells.（3）Ferulic acid gel was prepared,the gel quality was evaluated according to the pharmacopoeia,and the skin irritation test was conducted with ferulic acid gel according to relevant national standards.（4）A single dose of ⁶⁰Coγ-ray was used to irradiate Wistar rats（1.5 m from Wistar rats,and 266.24 c Gy/min dose rate）,so as to establish an animal model of radiation-induced skin damage lured by ⁶⁰Coγ-ray.In the model,ferulic acid gel with low（5%）,medium（10%）and high（15%）concentrations was used to detect the effect of ferulic acid gel on acute radioactive skin damage induced by ⁶⁰Coγ-ray in Wistar rats.（5）The control group,model group and medication administration group were scored by Douglas and Fowler radiodermatitis scoring standard.The skin blood flow changed at different time after irradiation were detected by Laser Doppler blood flow meter,using frequency sweep source OCT（sweep source-OCT,SS-OCT）system for radiation-induced skin injury in real time observation with non-invasive and non-radiation imaging.Enzyme linked immunosorbent assay（ELISA）was used to monitor the content of NLRP3 inflammasome,caspase-1,IL-18 and IL-1βin serum at different time.Pathological examination was carried out in skin tissues at different time after irradiation.Immunofluorescence was used to detect the expression of NLRP3 inflammasome and Caspase-1 in skin tissue.Results:（1）Ha Ca T cell model of radiation-induced skin injury was established by incubating Ha Ca T cells with 18 Gy ⁶⁰Coγ-ray for 24 h.The mechanism of cell injury was related to oxidative damage,apoptosis and inflammatory reaction.（2）Ferulic acid gels were prepared by using different concentrations of ferulic acid.Through quality evaluation,it was found that the gels were regular and exquisite on the whole,kept gelatinous at normal temperature,and had chemical stability without drying or liquefaction.The skin irritation test on Wistar rats showed that ferulic acid gel was mild,and no skin irritation reaction was found.（3）The animal models of acute radiation-induced skin injury were established by ⁶⁰Coγ-ray irradiation at 40Gy absorbed dose.After using ferulic acid gel with low（5%）,medium（10%）and high（15%）concentrations,the injury progresses were slowed down,the granulation tissue hyperplasia was accelerated and the radiation damage degree was decreased,showing a good anti-radiation effect.（4）Ferulic acid can refrain the expression of NLRP3 inflammasome,achieving anti-inflammatoryandanti-radiationeffectsthrough NLRP3-Caspase-1-IL-18-IL-1βpathway,thus significantly reducing radiation-induced skin injury.Conclusion:In order to study the damage and mechanism of Ha Ca T cells induced by different absorbed doses of ⁶⁰Coγ-ray,Ha Ca T cell model of radiation-induced skin damage was established for the first time.Studies on cell models have shown that the damage of Ha Ca T cells is closely related to the oxidative damage,apoptosis and inflammatory reaction of Ha Ca T cells induced by ⁶⁰Coγ-ray.Ferulic acid can protect Ha Ca T cells and observably reduce the damage of Ha Ca T cells caused by ⁶⁰Coγ-ray,which is related to the effective antioxidant and anti-inflammatory effects of ferulic acid.In this study,ferulic acid gel was applied to acute radiation skin injury for the first time.We found that ⁶⁰Coγ-ray could activate NLRP3 inflammatory corpuscle in rat skin tissue and induce the aggravation of inflammatory response in rats.After treatment with ferulic acid gel,the NLRP3inflammasome was inhibited in the serum and skin of rats.The expressions of downstream inflammatory cytokines IL-18 and IL-1βwere decreased,the degree of radiation-induced skin injury was reduced,and the recovery time was dramatically shortened,which was closely related to the anti-inflammatory,anti-oxidative and anti-radiation effects produced by ferulic acid gel.