The Study On Porphyromonas Gingivalis-induced Preterm Birth In Pregnant Rats

Preterm low birth weight(PLBW)in human,with less than 2500 grams of birth weight and under 37 weeks of gestational age,is one of the leading causes of perinatal mortality and morbidity.Pretenn Birth/Low birth weight(PTB/LBW)has been recognized as a syndrome with multiple risk factors,which has a far-reaching and long-lasting effect on the long-term health of the offspring.Abundant studies have demonstrated a tight connection between pregnant women with periodontitis and PTB/LBW in recent years.However,the specific mechanism of periodontitis-induced PTB/LBW is not fully understood.P.gingivalis,as one of the dominating periodontal pathogens,can make translocation to gestational tissue by directly invading it,or cause immune response of the mater or fetus by releasing inflammatory mediators through the circulatory system reaching the maternal-fetal interface.The placenta,as a vital organ between mater and fetus for physiologic exchange,plays a crucial role in the normal development of the fetus during gestation.Inflammation and damage of placental tissue is closely related with the incidence and development of PTB.At present,the relationship between P.gingivalis and PTB/LBW,and the pathogenesis of P.gingivalis-induced PTB/LBW are lack of comprehensive studies.To reveal the possible pathogenesis about P.gingivalis-induced PTB/LBW,has an important significance about preventing periodontal disease in pregnant woman,reducing the incidence of PTB/LBW and improving the quality of the population and eugenics.Objective:To investigate the role of PRgingivalis infection playing in birth weight and gestational day of neonates in rats,we established pregnant murine models of chronic periodontitis and tail vein injection.And we further analyzed the effects of P.gingivalis on systemic and local gestational tissue of rats,to make it clear what regulatory factors are linked to PTB/LBW of neonates.This study was conducted to provide theoretical basis for the pathogenesis of PLBW in pregnant women with periodontitis,and gave us new insight into clinical prevention and intervention in the occurrence of PLBW.Methods:The Wistar rats in both models were randomly divided into 3 groups:the P.gingivalis-infected group,negative control group and blank control group,respectively.A rat periodontitis model was established by periodontal ligature with the left mandibular 1st molars,and model of vein injection was established by tail intravenous puncture.The birth weight and gestational day of neonates were recorded.Placental tissues were collected from gdl8 rats in both models,amniotic fluid and blood of rats in the periodontitis model was harvested from 4 different periods.Amniotic fluid and serum samples were assessed for the levels of interferon(IFN)-y,interleukin(IL)-1(3,and IL-6 using rat ELISA kits.The immunofluorescence analysis were performed to assess the translocation of P.gingivalis to murine placentas.The expression levels of placental Fas,Fas ligand(FasL),Toll-like receptor 2(TLR2)and TLR4 were detected by immunohistochemical staining and Western blot analysis.Results:In the periodontitis model,rats with a PTB and LBW newborns were observed in the P.gingivalis-infected group.Additionally,the serum levels of IFN-y and IL-1p significantly increased in response to P.gingivalis,but no significant difference was observed in the amniotic fluid level.Moreover,with the translocation of P.gingivalis to placental tissues,remarkable changes in local gestational tissue were found,followed by significantly enhanced expression of TLR2 as well as Fas and FasL.However,the expression of TLR4 had no significant difference between P.gingivalis-inffeted group and negative control group.In the tail vein injection model,with the significant increased expression of placental Fas,FasL and TLR4,rats in the P.gingivalis-infected group showed significant LBW of neonates.Conclusion:In our periodontitis murine model,P.Rgingivalis translocates to placental tissues,triggering circulating inflammatory factors of IFN-y and IL-I?,and enhancing the expression of Fas,FasL,and TLR2 in local placental tissues,which subsequently induces PTB in rats.While in our tail vein injection model,P.Rgingivalis infection induces increased expression of placental Fas,FasL,and TLR4.Both models of P.gingivalis infection have a LBW of neonates.These results indicate that pregnant woman with periodontal infection inducing delivery of low birth weight babies,might be linked to P.gingivalis-induced dysregulation of placental Fas,FasL,TLR2 and TLR4,and disequilibrium in serum levels of inflammatory factors,as well as placental colonization of P.gingivalis.