The Inhibition And Mechanism Of White Tea Extract On Fibrosis In Rats Induced By Silicon Dioxide Nanoparticles

International Agency for Research on Cancer(IARC in 1997)has classified that SiO2 is a groupl carcinogen.Studies have shown that after SiO2 inhalation,the silica particles are rapidly translocated to different organs in the body such as lung and liver tissues where they promote accumulation of inflammatory cytokines that induces fibrosis.Studies have reported that white tea has a wide range of effects that are beneficial to health as it inhibits inflammation,modifying blood lipid and hypoglycemia,anti-ageing properties and so on.In this study,we investigated the inhibitory effect and mechanism of white tea on pulmonary and hepatic fibrosis induced by silica dioxide nanoparticles(nano-SiO2)in rats.The main results are as follows:1.In this experiment,silver needle and white peony were used as research materials.Tea extracts were obtained by extraction,concentration and freeze-drying.Biochemical analysis showed that polyphenol,caffeine and amino acids were higher in the silver needle tea extract than white peony extract.Whereas soluble sugar,flavonoids and protein were higher in white peony than silver needle tea extract.2.Pathological and morphological observation showed that white tea extract had a certain repairing effect on fibrous lung and liver tissues of rats that was induced by nano-SiO2.Through the observation of lung and liver index,visual observation,HE staining and semi-quantitative evaluation of fibrotic rats,white tea extract can reduce the quality of lung and liver tissue,directly affecting the decline of lung and liver index(P<0.05),and the pathological morphology of lung and liver fibrosis had obvious controled and reduced.After two weeks of intragastric administration of white tea extract,the reduction of fibrosis in rats could be directly reflected in the semi-quantitative score of fibrosis degree(P<0.05).3.White tea extract had a protective effect on nano-SiO2 induced oxidative stress in rat lung and liver tissues.The contents of NO and MDA in blood serum,lung and liver tissues increased after nano-SiO2 exposure whereas the activity of two main antioxidant enzymes SOD and GSH-Px decreased respectively.After 2 weeks of oral administration of white tea extract,the antioxidant activity of blood serum,in lung and liver tissues of fibrotic rats increased obviously.White tea extract significantly decreased the content of NO and MDA in blood serum of fibrotic rats(P<0.05),silver needle showed the best effect.White peony significantly increased the level of SOD(P<0.05)faster to compare with other treatments,and also significantly decreased NO levels in fibrous rat lung tissues(P<0.05).However,there was slight insignificant changes in SOD activity and MDA content(P>0.05).Especially,white tea extract effectively reduced the content of NO and MDA in liver tissue of fibrotic rats and increased the activity of SOD and GSH-Px.The changes of each index had statistical significance(P<0.05),among which silver needle had the best effect.White tea extract significantly decreased the concentration of IL-6 in lung and liver tissues of fibrotic rats(P<0.05),white peony had the best effect.In conclusion,white tea extract can significantly reduce the degree of hepatic and pulmonary fibrosis induced by nano-SiO2,also its abilities of scavenging free radicals and improving the pathological phenomenon of hepatic and pulmonary fibrosis through anti-oxidation and anti-inflammatory properties were proved.In this study,white tea extract provides a new possibility for the prevention and treatment of fibrosis.