Effects Of Zinc Sulfate Against UVB Damage

Background:Over the past few decades, human activities have been destroying the ozone layer in stratosphere, the radiation dose of UVB reaching the ground is increasing, which will contribute to the increasing chance of exposing to excessive UVB radiation. We have been exposed to harmful environmental factors all the time, our primary protective barrier is skin, which protects us from water loss, external physical, chemical and biological damage, such as trauma, UVB radiation, and microorganisms. UVB has higher energy and shorter wavelength, and can be almost completely absorbed by the epidermis, only 10-20% of the UVB energy can reach the basal layer and papillary layer of the epidermis, so keratinocytes in the skin are the main damage target of UVB radiation. UVB photons can be absorbed by molecules in the keratinocytes (chromophores and photosensitizers), which results in the subsequent series of biological effects, such as DNA damage, oxidative stress, immunosuppression, inflammation, apoptosis and so on. Zinc plays an important role in human development and body function mantainance, it is involved in the composition of many metal-binding enzymes. Zinc can play a protective antioxidative role by stabilizing lipid membranes and preventing lipid peroxidation caused by free radical, play as catalyst of enzymes in the process of DNA replication, gene transcription, RNA and protein production and has essential effects on cell survival, signal transduction, transcription and replication at the cellular level. Due to the high content of thiol components in metallothionein, metallothionein can maintain intracellular redox potential and neutralize glutathione (GSH) deficiency caused by oxidative stress. In this study, HaCaT cell damage model was established by UVB radiation, to study on the protective effects of Zinc Sulfate on damage of HaCaT cells caused by UVB by observing the cell survival rate, DNA damage, lipid peroxidation, apoptosis, so as to provide theoretical basis for prevention and treatment of UVB damage.Objective:To study the protective effects of Zinc Sulfate on damage of HaCaT cells caused by UVB and to investigate its antagonistic mechanism through etablishing UVB damage modle and administrating znic Sulfate before radiation.Methods:The cells were divided into normal group, Zinc group, UVB group, Znic&UVB group. Zinc Sulfate was administrated at 24h before irradiation, and then cells were radiated by UVB. Cell viability was measured by trypan blue staining method. MDA levels in HaCaT cells was measured by TBA assay. DNA damage was tested by single cell gel electrophoresis, cell apoptosis was detected by Western Blot and metallothionein and NF-κB/p65 expression were measured by immunohistochemistry.Results:1. Cell viability:Compared with normal group, cell viability of UVB group and Zn+UVB group were significantly less(P<0.05), cell viability of Zinc group had no significant change (P>0.05); compared with UVB group, cell viability of Zn+UVB group was significantly higher (P<0.05).2. MDA levels:Compared with normal group, MDA level in UVB group and Zn+UVB group increased (P<0.05); compared with UVB group, MDA level in Zn+UVB group decreased significantly (P<0.05).3. Comet assay tail moment and Olive tail moment:Compared with normal group, cell comet tail moment and Olive tail moment of UVB group and Zn+UVB group increased (P<0.05), cell comet tail moment and Olive tail moment of Zn group had no changes (P>0.05); compared with UVB group, cell comet tail moment and Olive tail moment of Zn+UVB group is shorter (P<0.05).4. Bax/Bcl-2 rate:Compared with normal group, Bax/Bcl-2 rate in UVB group increased (P<0.05), Bax/Bcl-2 rate in Zn group and Zn+UVB group decreased (P>0.05); compared with UVB group, Bax/Bcl-2 rate in Zn+UVB group decreased (P<0.05).5. MT expression levels:Compared with normal group, MT expression levels in Zn group, UVB group and Zn+UVB group increased (P<0.05); compared with UVB group, MT expression level in Zn+UVB group increased significantly (P<0.05).6. NF-κB/p65 expression levels:Compared with normal group, NF-κB/p65 expression level in UVB group increased (P<0.05), NF-κB/p65 expression levels in Zn group and Zn+UVB group had no changes; compared with UVB group, NF-KB/p65 expression level in Zn+UVB group decreased significantly (P<0.05).Conclusion:1. UVB can lead to lipid peroxidation, DNA damage of HaCaT cells and induce apoptosis.2. Zinc Sulfate can antagonize the damage effects of UVB on HaCaT.3. The increased MT expression level in HaCaT cells induced by Zinc Sulfate may be one of the mechanisms of Zinc Sulfate against UVB damage.4. The decreased expression level of NF-κB/p65 in HaCaT cells may be one of the mechanisms of Zinc Sulfate against UVB damage.