| Chronic periodontitis is one of the two most important oral diseases that cause the financial burden of the world,therefore,it is a major public health problem.The treatment of chronic periodontitis is mainly by manual debridement,repairing the shape of periodontal tissue to reduce plaque retention,and common auxiliary drugs are also concentrated in bactericidal effects,such as minocycline hydrochloride or other drugs.With the deepening of relevant research,the influence of the body's inflammatory response on the destruction of periodontal tissues has been paid more and more attention.The corresponding immunomodulatory drugs have also been gradually applied to control the periodontal inflammatory response,which may become one of the research directions in periodontal treatment in the future.Integrin-?9(ITGA9)is one of the members of the receptor integrin family on the cell membrane.It appears only in vertebrates and was discovered in 1991 and officially named in 1993.In the past 30 years of research,it has been found that integrin-?9 plays a role in growth and development,wound healing,cancer,and immune diseases,especially in the study of rheumatoid arthritis.The antibody of integrin-?9 injected into the joint cavity can effectively reduce the inflammatory response and inhibit the occurrence of joint swelling or bone resorption.Both rheumatoid arthritis and chronic periodontitis can destroy bone structure and surrounding soft tissue.Some studies have reported that they have some common characteristics in pathogenesis and pathological process,but there is still a lack of research on integrin-?9 in periodontal diseases.Therefore,we try to explore whether integrin-?9 is involved in the occurrence and development of chronic periodontitis,and provide more potential targets for the treatment of periodontitis in the future.This study intends to investigate whether integrin-?9 and its ligands play a role in the homeostasis of chronic periodontitis,and explore possible mechanisms.Divided into the following three parts:Experiment 1Expression of integrin-?9 in gingiva of patients with chronic periodontitis.Objective: To investigate the difference in the expression of integrin-?9 in the gingival tissues between healthy people and patients with chronic periodontitis.Methods: Collected the inflammatory gingiva removed during periodontal flap surgery(after initial treatment),and healthy gingiva from crown lengthening and second-stage implant surgery,detecting by HE and immunohistochemical staining,software scanning analysis of positive rate.Results: Patients with chronic periodontitis had significant inflammatory infiltration of gingival tissue,and the expression level of ITGA9 both in epithelial and lamina propria tissues was significantly higher than that in healthy people.Conclusion: In the microenvironment of chronic periodontitis,more integrin-?9 is expressed on the cell membrane of gingival epithelium and lamina propria cells.Experiment 2Analysis of ligands of integrin-?9 and inflammatory factors in gingival crevicular fluid of patients with chronic periodontitis.Objective: To detect the content of integrin-?9 ligands tenascin-C,osteopontin and inflammatory factors TNF-?,IL-6,IL-1? in the gingival crevicular fluid of healthy people and patients with chronic periodontitis.Methods: Gingival crevicular fluid was collected from the first molars of newly diagnosed chronic periodontitis patients(without periodontal treatment,periodontal pocket ?5mm)and healthy people(periodontal pocket <2mm,no loss of attachment),and the sample was measured by ELISA For the content of protein tenascin-C,the content of osteopontin,TNF-?,IL-6 and IL-1? was detected by BCA technique.Results: There was a significant difference between the tenascin-C in the gingival crevicular fluid of patients with chronic periodontitis and the healthy group(P <0.05),but there was no statistical difference in osteopontin(P = 0.829).There were statistical differences between the two groups in TNF-?(P < 0.05)and IL-1?(P <0.01).As shown by the results of the t-test,the average expression level of IL-6 was higher in the chronic periodontitis group,but it was not considered to be significantly different(P = 0.2028).Conclusion: The gingival crevicular fluid of patients with chronic periodontitis secretes more tenascin-C and inflammatory factors,but osteopontin does not increase or decrease significantly.Experiment 3Expression and mechanism of integrin-?9 in human periodontal ligament cells.Objective: To analyze whether integrin-?9 is expressed and plays a role in human periodontal ligament fibroblasts,and to explore related cell signal transduction pathways.Methods:(1)Culture primary periodontal ligament cells in vitro and observe whether integrin-?9 was expressed by immunofluorescence staining.(2)Add TNF-?(20ng /m L)to stimulate the cells,and observe the changes of m RNA levels of cells expressing integrin-?9 and its ligands.(3)Knock down integrin-?9 of periodontal ligament cells with small interfering RNA(si RNA),analyze the changes of inflammatory cytokines after detecting knockdown efficiency,and detect xpression changes of p-Erk1 / 2,Erk1 / 2,p-JNK,JNK,p-p38,p38.Results:(1)Human periodontal ligament cells expressed integrin-?9.(2)Under the stimulation of TNF-?,periodontal ligament cells will express more integrin-?9,tenascin-C and osteopontin.(3)ITGA9 gene knockdown to 40% can significantly inhibit the secretion of IL-1?,IL-6 and IL-8 from periodontal ligament cells.Western blot analysis showed that knocking down ITGA9 inhibited the phosphorylation ratio of Erk1/2,JNK,and p38.Conclusion: Human periodontal ligament cells express more integrin-?9 and its ligands in an inflammatory environment,and knocking down ITGA9 can reduce the secretion of interleukin factors under inflammatory stimulation.This change may be related to mitogen-activated protein kinase(MAPK)signalling pathway. |
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