Detection Of Rag Genotype Of Porphyromonas Gingivalis In Periodontitis Patients With Diabetes And Research Of Its Pathogenesis

BACKGROUND: Chronic Periodontitis(CP)is a chronic inflammatory disease caused by plaque,which leads to loss of connective tissue attachment,loss of alveolar bone support and formation of periodontal pockets.Diabetes mellitus(DM)is a chronic lifelong disease and one of the most serious chronic health problems in the world.A large number of epidemiological and clinical data show that diabetes mellitus(DM)and periodontitis interact.Periodontitis is a predisposing and promoting factor of diabetes.Diabetes can increase the risk and severity of periodontitis.At present,periodontitis has been listed as the sixth complication of diabetes.Porphyromonas gingivalis(P.gingivalis)is the main pathogen causing periodontitis,the rag locus was identified as one of the pathogenic island genes of P.gingivalis.Studies have confirmed that the inactivation of rag locus can reduce the pathogenicity of P.gingivalis and damage periodontal tissue.There are four different genotypes of rag locus in clinical strains,named rag-1,rag-2,rag-3 and rag-4 respectively.The pathogenicity of different genotypes is also different.Some studies have shown that periodontal inflammation and destruction in diabetic patients are more severe than those in non-diabetic patients.Although hyperglycemia increases local inflammatory and destructive responses in periodontal tissues through inflammatory immune and oxidative stress pathways,it may also be related to changes in the composition of subgingival microecosystems.Is the distribution of P.gingivalis of different rag types different between patients with diabetic periodontitis and patients with simple periodontitis,which leads to more periodontal inflammation and destruction of the former.At present,there are few studies.OBJECTIVE: Aim at analyzing the positive rate of P.gingivalis and the distribution of rag genotype in normal people,periodontitis with diabetes mellitus and periodontitis,in orderto explore the mechanism of diabetes mellitus in the pathogenesis of periodontitis.METHODS:All recruitments weredivided into three groups: diabetic periodontitis group,periodontitis group and normal group.The patients with diabetic periodontitis and periodontitis were selected as severe periodontitis patients.In each group,20 subjects were selected and saliva samples were collected.The detection rate and rag genotype of P.gingivalis in saliva were detected by qualitative method of PCR,and then the detection rate of P.gingivalis and rag genotype were analyzed by statistics.RESULTS: The results showed that the positive rate of salivary P.gingivalis in patients with periodontitis with diabetes mellitus was [65%(13/20)].The positive rate of salivary P.gingivalis in patients with chronic periodontitis was [70%(14/20)].Thepositive rate of salivary P.gingivalis in patients with periodontitis with diabetes mellitus was [65%(13/20)],[40%(8/20)] in normal group had no statistical difference(P>0.05);the detection of rag-1 gene in chronic periodontitis group [45%(9/20)] was significantly higher than that in chronic periodontitis group with diabetes mellitus[5%(1/20)],with statistical significance(P<0.05);the detection of rag-2 gene in normal group [62.5%(5/8)]was significantly higher than that in other two groups,with statistical significance(P<0.05);there was no statistical difference in rag4 and rag3 detection among the three groups(P>0.05).CONCLUSION: 1.The detection of rag-1 Porphyromonas gingivalis in saliva of patients with diabetic periodontitis is significantly lower than that of chronic periodontitis group,which may be related to the change of oral microenvironment inperiodontitis patients with diabetes and the decrease of rag-1 expression.In addition,the periodontal inflammatory state of periodontitis patients with diabetes may also occur the immune response triggered by Porphyromonas gingivalis to escape the hostdefense,and may also decrease rag-1 expression.2.The detection of rag-2 in the normal group was significantly higher than that in the other two groups,which suggested that Porphyromonas gingivalis in the healthy people was mainly low virulence rag-2,which may be one of the reasons for the occurrence of periodontitis in normal people.