Complement Activation Fragments in Cervicovaginal Fluid Are Associated with Intra-Amniotic Infection/Inflammation and Spontaneous Preterm Birth in Women with Preterm Premature Rupture of Membranes

Abstract

Objective: We sought to determine whether the levels of complement and other inflammatory and angiogenic mediators in cervicovaginal fluid (CVF) are independently associated with intra-amniotic infection and/or inflammation (IAI) and imminent spontaneous preterm birth (SPTB, ≤48 hours of sampling) in women with preterm premature rupture of membranes (PPROM). Study design: This was a retrospective study consisting of 85 singleton pregnant women with PPROM at 20+0 to 33+6 weeks. Amniotic fluid (AF) obtained via amniocentesis was cultured and assayed for interleukin-6. CVF samples collected at the time of amniocentesis were assayed for complement C3a, C4a, and C5a, HSP70, M-CSF, M-CSF-R, S100 A8, S100 A9, thrombospondin-2, VEGF, and VEGFR-1 by ELISA. Results: Multivariate logistic regression analyses revealed that elevated CVF concentrations of complement C3a, 4a and 5a were significantly associated with an increased risk of IAI and imminent SPTB, whereas those of M-CSF were associated with IAI, but not imminent SPTB (P=0.063), after adjustment for baseline covariates (e.g., gestational age at sampling). However, univariate and multivariate analyses showed that the CVF concentrations of angiogenic (thrombospondin-2, VEGF, and VEGFR-1) and inflammatory (HSP70, M-CSF-R, S100 A8, and S100 A9) proteins were not associated with either IAI or imminent SPTB. Conclusions: In women with PPROM, elevated CVF concentrations of complement C3a, C4a, and C5a are independently related to an increased risk of IAI and imminent SPTB. These findings suggest that complement activation in CVF is significantly involved in mechanisms underlying preterm birth and in the host response to IAI in the context of PPROM.

Expression of inflammatory, angiogenic, and extracellular matrix‐related mediators in the cervicovaginal fluid of women with preterm premature rupture of membranes: Relationship with acute histological chorioamnionitis

“…Nevertheless, there is a paucity of data regarding M‐CSF and inflammatory/infectious changes concerning preterm birth. Recent studies from our group have demonstrated that elevated M‐CSF levels in the CVF are independently associated with IAI in pregnancies complicated by PPROM and MIAC in women presenting with preterm labor 23,57 . Similarly, in the present study, we found that elevated CVF levels of M‐CSF are associated with microbial‐associated HCA (but not acute HCA), as well as acute HCA severity (Table S2).…”

“…Recent studies from our group have demonstrated that elevated M-CSF levels in the CVF are independently associated with IAI in pregnancies complicated by PPROM and MIAC in women presenting with preterm labor. 23,57 Similarly, in the present study, we found that elevated CVF levels of M-CSF are associated with microbialassociated HCA (but not acute HCA), as well as acute HCA severity (Table S2). However, further studies are needed to clarify the underlying mechanism and role of M-CSF in the CVF compartment associated with inflammation in the placenta and its relationship to infection in the amniotic cavity during pregnancy.…”

“…It is worth noting that, despite these significant relationships, the AUC values of the aforementioned CVF biomarkers ranged within 0.61−0.77, thereby demonstrating poor to fair diagnostic potential for predicting each corresponding endpoint related to acute HCA 46 . Furthermore, some important inflammatory proteins (APRIL, DKK‐3, lipocalin‐2, MIP‐1α, S100A8A9, MMP‐9, VDBP, uPA) were not found to be altered in the CVF of patients with acute HCA or microbial‐associated HCA, whereas previous reports showed that these proteins are elevated in the CVF of women with MIAC/IAI or in the AF of women with acute HCA complicated by PPROM 17,22,23 . These discrepancies can be explained as follows: (i) primarily, HCA‐related inflammation/infection can develop in the interval between CVF sampling and placenta delivery, particularly by an ascending route through the ruptured membranes from the vagina and cervix; (ii) CVF specimens could have been contaminated with vaginal or cervical microbes; thus, inflammatory protein levels measured in the CVF, although it was mixed with AF leaked into vagina, may not completely reflect the inflammatory/infectious state of the amniotic cavity; (iii) early stage ascending intra‐uterine inflammation/infection might be limited to the chorio‐decidua before eliciting inflammatory responses in the amniotic cavity; and (iv) non‐infectious factors, including danger signals, may also contribute to the development of placental inflammation 5 .…”

“…Indeed, significant positive correlations were reported between the levels of inflammatory mediators in the CVF and AF compartments in women with PPROM 18–21 . Moreover, various inflammatory and immune mediators in CVF samples were described as useful biomarkers for identifying high risk for intra‐amniotic inflammation (IAI), MIAC, and imminent spontaneous preterm delivery (SPTD) in pregnancies complicated by PPROM 18,22–25 . However, very few studies have explored the relationship between CVF inflammatory proteins and acute HCA, and those that have were limited by small sample sizes, small number of targeted inflammatory proteins (e.g., interleukin [IL]−6/8 and/or matrix metalloproteinase [MMP]−8), and a lack of adjustment for potential confounding factors (i.e., gestational age [GA] at sampling) 24,26,27 …”

“…[18][19][20][21] Moreover, various inflammatory and immune mediators in CVF samples were described as useful biomarkers for identifying high risk for intra-amniotic inflammation (IAI), MIAC, and imminent spontaneous preterm delivery (SPTD) in pregnancies complicated by PPROM. 18,[22][23][24][25] However, very few studies have explored the relationship between CVF inflammatory proteins and acute HCA, and those that have were limited by small sample sizes, small number of targeted inflammatory proteins (e.g., interleukin…”