Effects Of Chronic Apical Periodontitis Induced By Enterococcus Faecalis On Inflammatory Response Of Aorta In High-fat Diet Rats

Objective:To investigate the effects of CAP induced by E.faecalis on serum inflammatory cytokines,serum lipid and inflammatory response of aorta in high-fat diet rats.Methods:Thirty-two Sprague-Dawley rats were fed either HFD or ND for 12 weeks.Serum TG,TC,HDL-C and LDL-C of SD rats in two groups were assayed in 6^thweek to confirm the establishment of the hyperlipidemia model.After that,ND and HFD group were divided into two subgroups,namely sham-operated and Ef-CAP group.For CAP induced by E.faecalis,small cotton containing E.faecalis suspension was inserted into the pulp chamber of the first and second right molar tooth.After 12 weeks,the maxilla and mandible of two groups were harvested and scanned by micro-CT to determine the presence of alveolar bone resorption area.Serum TNF-α,IL-6,IL-1α,IL-1β,MCP-1concentrations were measured by MILLIPLEX MAP Rat Cytokine/Chemokine Panel Kit.The biochemical autoanalyzer was used to measure the level of lipids.Histological examinations of aorta performed.We then used Quantitative Real-time PCR technology for TNF-α,MCP-1,IL-6,IL-1β,ICAM-1 measurement in the aorta.Results:（1）After 6 weeks of high-fat diet feeding,the value of AI and LDL-C of high-fat diet rats were significantly higher than those of normal diet（P<0.05）.All the animals of ND+Ef-CAP and HFD+Ef-CAP group showed bone resorption area.（2）Compared with the ND group,the levels of HDL-C in the HFD and ND+Ef-CAP decreased（P<0.05）;there was no significant difference in serum lipid levels between the HFD+Ef-CAP and HFD group.（3）Compared with the ND group,the expression levels of TNF-α,MCP-1,IL-6,IL-1βand IL-1αin the HFD group was increased（P<0.05）,and the ND+Ef-CAP increased the expression of IL-6 level（P<0.05）.Compared to the ND+Ef-CAP group,serum TNF-α,IL-1α,IL-6,IL-1βwere significantly higher in HFD+Ef-CAP group（P<0.05）.Serum TNF-αin HFD+Ef-CAP group was significantly higher than that of HFD group（P<0.05）.（4）Inflammatory cells were observed in tunica intima in HFD,ND+Ef-CAP and HFD+Ef-CAP group.Compared to the ND group,there were no significant changes in mRNA expressions of inflammatory factors in the HFD and ND+Ef-CAP group.Compared with ND group,the mRNA expressions of TNF-α,ICAM-1 and MCP-1 in the HFD+Ef-CAP group were increased（P<0.05）;the mRNA expressions of TNF-αand MCP-1 were markedly elevated in the HFD+Ef-CAP group than that of ND+Ef-CAP and HFD group（P<0.05）.Conclusions:（1）Ef-CAP can change some serum lipid levels of rats,but it had almost no effect on serum lipid levels in hyperlipidemia rats.（2）Ef-CAP can elevate serum concentration of inflammatory cytokines of rats,and it can cause more serious in hyperlipidemia rats,which may aggravate the systemic inflammatory response in hyperlipidemia rats.（3）CAP can promote the inflammatory response of aorta in hyperlipidemic rats,yet it still can not cause atherosclerotic plaque formation.