Fetal Membrane Inflammation Induces Preterm Birth Via Toll-Like Receptor 2 in Mice With Chronic Gingivitis

Abstract

Inflammation is associated with preterm birth. We previously described a mouse model of chronic inflammation-induced preterm birth after dental Porphyromonas gingivalis infection. The aim of this study was to employ this model system to investigate the mechanisms through which enhanced uterine contractility induces preterm birth. Messenger RNA (mRNA) encoding contraction-associated proteins, such as oxytocin receptors, was measured at various gestational time points by real-time polymerase chain reaction (PCR). Spontaneous and oxytocin-induced uterine contractile activity at gestational day 18 was assessed using a tissue organ bath. The expression levels of Toll-like receptor 2 (TLR2), TLR4, cyclooxygenase (COX)-2, nuclear factor-kappa B (NF-κB) p65, and p38 mitogen-activated protein kinase (MAPK) on gestational day 18 were also determined by real-time PCR or Western blotting. Messenger RNA encoding contraction-associated proteins was increased at gestational day 18, and the spontaneous contractile activity (1.6-fold greater area under the contraction curve) and sensitivity to oxytocin (EC: 8.8 nM vs 2.2 nM) were enhanced in the P gingivalis group compared to those in the control group. In the P gingivalis group, COX-2 mRNA expression was not elevated in the placenta or myometrium but was upregulated 2.3-fold in the fetal membrane. The TLR2 mRNA levels in the fetal membrane were 2.7-fold higher in the P gingivalis group, whereas TLR4 levels were not elevated. Activation of the NF-κB p65 and p38 MAPK pathways was enhanced in the fetal membrane of the P gingivalis group. Thus, in mice with chronic dental P gingivalis infection, TLR2-induced inflammation in the fetal membrane leads to upregulation of uterine contractility, leading to preterm birth.

Progesterone Suppresses Uterine Contraction by Reducing Odontogenic Porphyromonas gingivalis Induced Chronic Inflammation in Mice

“…Experiments on uterine contraction have been described previously [ 14 ]. Briefly, strips of uterine smooth muscle (~5 mm wide and ~7 mm long) were suspended vertically between two steel wires in an organ chamber containing 10 mL of modified Krebs solution bubbled with 5% CO 2 and 95% O 2 (pH 7.4, 37 °C) at gestation day 18.0.…”

“…The PCR conditions were as follows: 1 cycle at 95 °C for 10 min, followed by 40 cycles at 95 °C for 15 s and 56 °C for 60 s. Primer sequences were as follows: mouse IL-8 forward:5′-CGC TGC TGC TGC TGG CCA CCA-3′ and reverse:5′-GGT TAT GAC TTC GGT TTG GGT GCA G-3′ [ 12 ]. The other gene primers used for real-time PCR have been previously described [ 11 , 14 ]. The expression of each gene was normalized to that of the housekeeping gene, GAPDH.…”

Role of galectin-glycan circuits in reproduction: from healthy pregnancy to preterm birth (PTB)

“…Enhanced placental TLR-4 expression was observed after oral infection with C. rectus and P. gingivalis [112]. In a mouse model with P. gingivalis infection, TLR-2-induced inflammation in the fetal membrane (activation of NF-kappaB and p38 MAPK pathways) leads to the upregulation of uterine contractility causing preterm delivery [113]. Similarly, P. gingivalis LPS induced IL-6 and IL-8 production via TLR-2 in human chorion-derived cells [114].…”

Protease activities of vaginal Porphyromonas species disrupt coagulation and extracellular matrix in the cervicovaginal niche

“…P. gingivalis can also disseminate via the bloodstream to distal infection sites such as the endocardium and joints 34,35 . During pregnancy, P. gingivalis has been isolated from the placenta and amniotic fluid of women who delivered preterm [36][37][38] , and in mouse infection models, P. gingivalis induces preterm labor via inflammatory activation of the chorioamniotic membranes 34,39,40 . Pathogenesis mechanisms contributing to these outcomes include a wide array of proteolytic activities carried out by numerous secreted proteases.…”