Cervical Expression of Elafin and SLPI in Pregnancy and Their Association With Preterm Labor

Afterbirth oral fluid secretory leukocyte protease inhibitor decreased in acute histologic chorioamnionitis in preterm birth

BACKGROUND

Secretory leukocyte protease inhibitor (SLPI) is an innate anti-inflammatory and anti-microbial peptide and produced in amnion of fetal membranes during pregnancy. However, studies on the association between SLPI levels in amniotic fluid and acute chorioamnionitis are limited. Afterbirth oral fluid (AOF) of the baby could be useful for representing the intra-amniotic environment precisely just before delivery. This study aimed to determine the relationship between SLPI levels in AOF and acute histologic chorioamnionitis (HC).

METHODS

AOF of the baby was obtained during delivery from 24(0/7) to 36(6/7) weeks of gestational age (preterm group, n = 94) and from 37(0/7) to 41(6/7) weeks of gestational age (term group, n = 27) just after birth. SLPI expression levels among five classifications were compared to the intensity of acute HC as follows: no inflammation, acute subchorionitis, acute chorionitis, acute chorioamnionitis, and funisits. The SLPI and matrix metalloproteinase-8 (MMP-8) concentrations of AOF were determined using Enzyme Linked Immunosorbent Assay. Histologic examination of the placenta and membranes was performed after delivery.

RESULTS

SLPI concentrations in AOF inversely decreased according to the intensity of acute HC (161.62 ng/mL in funisitis, 134.83 ng/mL in acute chorioamnionitis, 749.35 ng/mL in acute chorionitis, 953.05 ng/mL in acute subchorionitis, and 1126.77 ng/mL in no inflammation [p = .021]). The MMP-8 concentrations in AOF and maternal serum C-reactive protein were the highest in funisitis. The SLPI/ MMP-8 ratio was low in subgroup with acute chorioamnionitis and funisitis.

CONCLUSION

Along with increased MMP-8 levels, decreased SLPI levels in AOF of the baby could be an additional factor in predicting acute HC immediately after birth.

Pathological roles of antimicrobial peptides and pro-inflammatory factors secreted from the cervical epithelium in Gardnerella vaginalis-abundant vaginal flora in pregnancy

Bacterial vaginosis due to Gardnerella vaginalis (GV) is one of the main causes of preterm birth. Antimicrobial function of the cervical glands prevents ascending pathogen infection. This study investigated the effect of GV on the cervical gland cells. We examined the correlation between GV and neutrophil elastase in the cervical mucous obtained from pregnant women's clinical samples. Culture supernatants (sup) of GV and Lactobacillus crispatus (LC) were added to human immortalized cervical gland cells (EndoCx). Quantitative reverse transcription PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were used to examine the effects on the production of antimicrobial peptides (AMPs), secretory leukocyte peptidase inhibitor (SLPI), and Elafin. mRNA microarray analysis revealed the expression profile of GV-exposed EndoCx. Moreover, the antimicrobial activity of Elafin against LC and GV was investigated. In the clinical samples, neutrophil elastase was increased in the GV-positive cervical mucous. In an in vitro assay, RT-qPCR and ELISA showed that GV-sup enhanced the secretion of Elafin, but not SLPI, from EndoCx, whereas LC-sup did not. mRNA microarray assay and ELISA results demonstrated that GV-sup enhanced the proinflammatory pathway and interleukin (IL)- 8 secretion from EndoCx as well as cell adhesion and tight junction pathways. Moreover, GV-sup directly enhanced Elafin and IL-8 secretion from the cervical gland cells. In the GV-abundant vaginal flora, IL-8 level increased the neutrophil elastase activity and Elafin inhibited the elastase activity to protect from tissue damage and infection. Thus, the balance of IL-8-induced neutrophil and Elafin-induced antiprotease activities may be crucial in preterm labor.

The Interplay Between Cervicovaginal Microbial Dysbiosis and Cervicovaginal Immunity

The cervicovaginal microbiota plays a key role in the health and reproductive outcomes of women. In reality epidemiological studies have demonstrated that there is an association between the structure of cervicovaginal microbiota and reproductive health, although key mechanistic questions regarding these effects remain unanswered and understanding the interplay between the immune system and the structure of the cervicovaginal microbiota. Here, we review existing literature relating to the potential mechanisms underlying the interaction between vaginal microbes and the immune system; we also describe the composition and function of the microbiome and explain the mechanisms underlying the interactions between these microbial communities and various aspects of the immune system. Finally, we also discuss the diseases that are caused by disorders of the reproductive tract and how the immune system is involved. Finally, based on the data presented in this review, the future perspectives in research directions and therapeutic opportunities are explored.

The vaginal microbiota and innate immunity after local excisional treatment for cervical intraepithelial neoplasia

BACKGROUND

Vaginal microbiota (VMB) composition is altered in women with cervical intra-epithelial neoplasia (CIN) compared to healthy controls and is associated with disease progression. However, the impact of CIN excision on the VMB and innate immunity is not known. This observational study aims to explore the impact of CIN excision on the VMB, antimicrobial peptides (AMP) and proinflammatory cytokines.

METHODS

We sampled 103 non-pregnant, premenopausal women at the time of excisional treatment for CIN and at their 6-month follow-up visit. A further 39 untreated controls with normal cytology were also sampled. We used metataxonomics to group vaginal swab samples into community state types (CSTs) and ELISA to quantify cytokine and AMP levels in matched vaginal secretions. Analyses were performed to compare the bacterial composition and immune analyte levels before and after CIN excision and in healthy controls.

RESULTS

Women with CIN had significantly higher rates of Lactobacillus species depletion pre-treatment compared to healthy controls (CST IV 21/103, 20% vs 1/39, 3%, p = 0.0081). Excision did not change the VMB composition, with CST IV remaining significantly more prevalent after excision compared to untreated, healthy controls (CST IV 19/103, 20% vs 1/39, 3%, p = 0.0142). Prevotella bivia and Sneathia amnii were significantly higher in samples before treatment compared to untreated controls, and Prevotella bivia remained significantly higher amongst the treated, with less Lactobacillus crispatus compared to untreated controls. IL-1β and IL-8 remained significantly elevated pre- (p < 0.0001 and p = 0.0014, respectively) and post-treatment (p < 0.0001 and p = 0.0035, respectively) compared to untreated controls. Levels of human beta-defensin-1 and secretory leukocyte protease inhibitor were both significantly reduced following CIN excision (p < 0.0001); however, their levels remained lower than controls post-treatment.

CONCLUSIONS

Women with CIN have an increased prevalence of Lactobacillus sp. depletion, high-diversity VMB composition, and higher levels of proinflammatory cytokines and AMPs compared to normal controls. Surgical excision of the disease reduces levels of vaginal AMPs but does not alter VMB composition or cytokine levels. These findings suggest that women with CIN have an inherent predisposition to a high-diversity proinflammatory environment that is not corrected by disease excision. The failure to re-establish a Lactobacillus-enriched CST may explain why women remain at high risk of pre-invasive and invasive disease recurrence.

Evaluation of trappin-2 in cervicovaginal secretions as predictor of spontaneous preterm birth in asymptomatic high-risk women: Nested case-control study

OBJECTIVE

To evaluate trappin-2 levels in cervicovaginal secretions for prediction of spontaneous preterm birth (sPTB) and compare it with transvaginal sonography (TVS) cervical length in asymptomatic women at risk of PTB.

METHODS

Trappin-2 levels assessed in cervicovaginal secretions collected from 80 asymptomatic pregnant women at high risk for preterm delivery and cervical length measured by TVS, first at 14-20 weeks of pregnancy and repeated 8 weeks later. On the basis of delivery outcomes, participants were divided into cases (delivery <37 weeks) and controls (delivery at 37-41 weeks).

RESULTS

The mean value of cervicovaginal trappin-2 was significantly higher in women who delivered preterm (n = 40), compared with the term group (n = 40: P < 0.001) both at 14-20 weeks and at 22-28 weeks. The critical cut-off value for cervicovaginal trappin-2 at 14-20 weeks was 4620 pg/mL, above which participants delivered prematurely with sensitivity, specificity, and positive and negative predictive values of 82.5%, 71.0%, 78.5%, and 81.5% respectively, whereas TVS cervical length in this window period was not significantly associated with preterm birth. At 22-28 weeks a trappin-2 value of 6900 pg/mL had similar predictive accuracy.

CONCLUSION

Raised cervicovaginal trappin-2 levels can be used as an early tool for prediction of PTB as early as 14-20 weeks (earlier than TVS) in asymptomatic high-risk women.

Secretory leukocyte protease inhibitor and progranulin as possible regulators of cervical remodeling in pregnancy

Secretory leukocyte protease inhibitor (SLPI) and progranulin (PGRN) are secretory proteins with an anti-inflammatory property. Their involvement in cervical remodeling in pregnant uterus is not yet elucidated. Thus, this study aimed to explore the significance of SLPI and PGRN in the maintenance of pregnancy by investigating the factors associated with their expression levels at the cervix. Concentrations of SLPI and PGRN proteins were measured in cervical mucus samples collected from asymptomatic pregnant women at 24-26 weeks of gestation (n = 166). The concentrations of those molecules were analyzed with clinical parameters related to risk for preterm delivery (PD). In pregnant mice, we evaluated the effect of lipopolysaccharide-induced inflammation and progesterone effect modulation on cervical mRNA expression of SLPI and PGRN. The cervical PGRN level was significantly lower in women with short cervix (<35 mm) and with a history of threatened PD. In women with short cervix, cervical SLPI concentrations were positively correlated with inflammatory cytokines, interleukin-6 (R² = 0.75) and interleukin-8 (R² = 0.71). In pregnant mice, cervical mRNA expressions of PGRN and SLPI were increased in response to progesterone supplementation and were suppressed by a progesterone antagonist, mifepristone. Lipopolysaccharide-induced inflammation caused remarkable upregulation in cervical SLPI mRNA level but not in PGRN. Progesterone and local inflammation are the factors controlling expression levels of PGRN and SLPI at the cervix. The observed relationship of PGRN and SLPI levels in the cervical mucus with PD-related clinical parameters supports that those anti-inflammatory molecules possibly play a significant role in appropriate regulation of cervical remodeling.

Differences in maternal gene expression in Cesarean section delivery compared with vaginal delivery

Cesarean section (CS) is recognized as being a shared environmental risk factor associated with chronic immune disease. A study of maternal gene expression changes between different delivery modes can add to our understanding of how CS contributes to disease patterns later in life. We evaluated the association of delivery mode with postpartum gene expression using a cross-sectional study of 324 mothers who delivered full-term (≥ 37 weeks) singletons. Of these, 181 mothers had a vaginal delivery and 143 had a CS delivery (60 with and 83 without labor). Antimicrobial peptides (AMP) were upregulated in vaginal delivery compared to CS with or without labor. Peptidase inhibitor 3 (PI3), a gene in the antimicrobial peptide pathway and known to be involved in antimicrobial and anti-inflammatory activities, showed a twofold increase in vaginal delivery compared to CS with or without labor (adjusted p-value 1.57 × 10^–11 and 3.70 × 10^–13, respectively). This study evaluates differences in gene expression by delivery mode and provides evidence of antimicrobial peptide upregulation in vaginal delivery compared to CS with or without labor. Further exploration is needed to determine if AMP upregulation provides protection against CS-associated diseases later in life.

Cervicovaginal natural antimicrobial expression in pregnancy and association with spontaneous preterm birth

There is much interest in the role of innate immune system proteins (antimicrobial peptides) in the inflammatory process associated with spontaneous preterm birth (sPTB). After promising pilot work, we aimed to validate the association between the antimicrobial peptides/proteins elafin and cathelicidin and sPTB. An observational cohort study of 405 women at high-risk, and 214 women at low-risk of sPTB. Protein concentrations of elafin and cathelicidin, and the enzyme human neutrophil elastase (HNE) were measured in over 1,000 cervicovaginal fluid (CVF) samples (10 to 24 weeks’ gestation). Adjusted CVF cathelicidin and HNE concentrations (but not elafin) were raised in high-risk women who developed cervical shortening and who delivered prematurely and were predictive of sPTB < 37 weeks, with an area under the curve (AUC) of 0.75 (95% CI 0.68 to 0.81) for cathelicidin concentration at 14 to 15⁺⁶ weeks. Elafin concentrations were affected by gestation, body mass index and smoking. CVF elafin in early pregnancy was modestly predictive of sPTB < 34 weeks (AUC 0.63, 0.56–0.70). Alterations in innate immune response proteins in early pregnancy are predictive of sPTB. Further investigation is warranted to understand the drivers for this, and their potential to contribute towards clinically useful prediction techniques.

Neutrophil elastase in cervical fluid in women with short cervical length

OBJECTIVE

The aim of the study was to determine the relationships between short cervical length (CL) and levels of cervical fluid neutrophil elastase (NE), secretory leukocyte protease inhibitor (SLPI), and interleukin 8 (IL-8) in the second trimester of pregnancy of women who underwent ultrasound-indicated cervical cerclage.

MATERIALS AND METHODS

CL of <25 mm or cervical funneling were included in the short CL group (n = 26) and the normal CL group (n = 22) included women who had CL of ≥25 mm and had no cervical funneling in women between 17 + 0 and 24 + 6 weeks of gestation. Levels of NE, SLPI, and IL-8 were measured by using enzyme-linked immunosorbent assay kits. Mann-Whitney U tests and Spearman's correlation analysis were used for statistical analyses.

RESULTS

Compared with the normal CL group, the short CL group had significantly higher median NE levels (P < 0.001) and higher, though not significant, median IL-8 levels by approximately three times (2107.0 vs. 798.3 pg/mL, P = 0.132). The median SLPI levels in cervical fluid was similar between the two groups (107.6 vs. 103.2 ng/mL, P = 0.499). Short CL had a significant correlations with cervical fluid NE levels (r = -0.475, P = 0.001).

CONCLUSION

Increased cervical fluid NE associated with cervical shortening in second trimester of pregnancy, whereas cervical fluid SLPI had constant levels.

Discovery of Antimicrobial Peptides in Cervical-Vaginal Fluid from Healthy Nonpregnant Women via an Integrated Proteome and Peptidome Analysis

Cervical-vaginal fluid (CVF) covers the lower part of the female reproductive system and functions in the homeostasis and immunity of the surrounding tissues. In contrast to the CVF proteome of both nonpregnant and pregnant women, the CVF peptidome has not been reported to date. In the current study, we identified 1087 proteins in CVF, of which 801 proteins were not previously identified in CVF proteomes. The presence of the tissue-specific proteins oviductal glycoprotein 1 and tubulin polymerization-promoting protein family member 3 strongly suggests that the tissues of the upper female reproductive tract contribute to the protein composition of CVF. The tremendous catalytic potential of CVF was highlighted by the identification of 85 proteases and the detection of pH-dependent trypsin-like proteolytic activity. Over 1000 endogenous peptides were detected in the CVF peptidome, and 39 peptides are predicted to have antimicrobial activity. The detailed proteomic and peptidomic analysis of CVF will further aid in the delineation of pathways related to reproduction, immunity and host defense, and assist in developing new biomarkers for malignant and other diseases of the female reproductive tract. Data are available via ProteomeXchange with identifiers PXD004450 (CVF peptidome) and PDX004363 (CVF proteome).

Labor prediction based on the expression patterns of multiple genes related to cervical maturation in human term pregnancy

PROBLEM

This study explored the possibility of evaluating cervical maturation using swabbed cervical cell samples at term pregnancy, and aimed to develop a novel approach to predict labor onset.

METHOD OF STUDY

Women with uncomplicated pregnancies (n=117 from 62 women at term pregnancy) were recruited. Messenger RNA expression levels of cervical cells for ten genes were quantified by qPCR. Principal component analysis (PCA) was conducted, and principal components that significantly contributed to the prediction of days to delivery were determined.

RESULTS

PCA demonstrated that 76% of the expression information from the ten genes can be represented by three principal components (PC1-3). By the multiple regression analysis, PC2 and Bishop score but not PC1 or PC3 were significant variables in the prediction of days to delivery.

CONCLUSION

These findings support the concurrent assessment of multiple gene activities in cervical cells as a promising approach to predict the initiation of labor.

The impact of pregnancy on anti-HIV activity of cervicovaginal secretions

BACKGROUND

Mucosal immunity of the female genital tract plays a critical role in defense against sexually transmitted infections like HIV. Pregnancy is associated with both structural and immunologic alterations in the genital mucosa, but the impact of these changes on its ability to suppress HIV infection is unknown. Current epidemiologic data are conflicting as to whether pregnancy increases the risk of HIV acquisition.

OBJECTIVE

The purpose of this study was to define the association between antimicrobial peptides and chemokines in cervicovaginal secretions and in vitro HIV infectivity among pregnant and nonpregnant women.

STUDY DESIGN

Forty pregnant and 37 nonpregnant women were enrolled in a prospective longitudinal cohort study at a single tertiary care women's hospital in Providence, RI. Cervicovaginal lavage was performed at each study visit. For pregnant women, study visits occurred once per trimester, and there was an optional postpartum visit. For nonpregnant women, study visits occurred across a single cycle that was timed to occur in the proliferative, ovulatory, and secretory phases based on the presumption of a regular menstrual cycle. The impact of cervicovaginal lavage on HIV infectivity was evaluated using a TZM-bl assay and compared between pregnant and nonpregnant women for each visit. The previously validated TZM-bl assay, which uses a luciferase reporting gene to indicate HIV infection of TZM-bl cells, was measured with a luminometer with higher relative light units that indicate greater levels of in vitro HIV infection. Immune mediators were measured with a multiplex bead assay. HIV infectivity and median concentration of each mediator were compared between pregnant and nonpregnant groups with the Wilcoxon rank sum test.

RESULTS

Cervicovaginal fluid from pregnant and nonpregnant women significantly decreased HIV infectivity in both groups compared with positive control (virus only; P<.01), but infectivity was not different between groups (P≥.44). During the second and third trimesters, pregnant women experienced suppression of several cervicovaginal immune mediators that included human beta defensin-2; lactoferrin; macrophage inflammatory protein-3α; regulated on activation, normally T-cell expressed and secreted; and stromal cell-derived factor-1 (all P≤.05). The antimicrobial peptide elafin was significantly correlated with HIV infectivity in both groups across all visits, except at the postpartum visit in the pregnant group (n=16). Secretory leukocyte protease inhibitor also was correlated significantly with infectivity across all visits, but in nonpregnant women only (P≤.03).

CONCLUSION

Cervicovaginal secretions from both pregnant and nonpregnant women contain immune mediators that are associated with HIV infectivity in an in vitro assay; however, infectivity was not different between pregnant and nonpregnant groups. If pregnant women are at increased risk for HIV infection, it is unlikely to be mediated by alterations in the effectiveness of these protective secretions.

Elevated concentration of secretory leukocyte protease inhibitor in the cervical mucus before delivery

BACKGROUND

Cervical remodeling during parturition progresses under exquisite regulation by immunologic mediators and proteases. Secretory leukocyte protease inhibitor is a secretory protein that can function as an antimicrobial peptide, an antiinflammatory molecule, and a protease inhibitor. The involvement of secretory leukocyte protease inhibitor in cervical remodeling before and during parturition is understood poorly.

OBJECTIVE

We aimed to reveal the role of secretory leukocyte protease inhibitor in the cervical remodeling process before normal term delivery and to evaluate its utility as a predictive biomarker for timing of delivery.

STUDY DESIGN

Cervical mucus samples were collected prospectively at weekly prenatal visits from a cohort of pregnant women at term. The secretory leukocyte protease inhibitor concentrations in 95 mucus samples that were obtained from 49 women with uncomplicated pregnancy who subsequently underwent normal vaginal delivery were assessed. Alterations in secretory leukocyte protease inhibitor concentrations at term and the association of secretory leukocyte protease inhibitor levels with the time to delivery were analyzed.

RESULTS

A moderate positive correlation with significance was detected between cervical mucus secretory leukocyte protease inhibitor concentrations and days to delivery (r = 0.38; P = .0001). The secretory leukocyte protease inhibitor concentration was significantly higher in samples that were collected within 7 days of delivery when compared with samples that were collected >7 days before delivery (P = .001). Secretory leukocyte protease inhibitor concentrations were also significantly higher in samples from women with premature rupture of membranes when compared with those without premature rupture of membranes (P = .01), all of whom delivered within 7 days. A logistic regression analysis revealed that the cervical secretory leukocyte protease inhibitor level was a significant parameter for the prediction of the onset of delivery. (P = .017; unit odds ratio, 1.28; 95% confidence interval, 1.07-1.61). A cut-off value of cervical secretory leukocyte protease inhibitor/total protein to predict delivery within 7 days was determined to be 1.62 μg/mg (sensitivity, 0.69; specificity, 0.72) using receiver operating characteristic curve-analysis.

CONCLUSION

Secretory leukocyte protease inhibitor concentrations in the cervical mucus elevate progressively before delivery in uncomplicated term pregnancies. Our findings suggest that cervical secretory leukocyte protease inhibitor is a candidate biomarker for delivery prediction.

Small Peptides with a Big Role: Antimicrobial Peptides in the Pregnant Female Reproductive Tract

There is a growing interest in the role of antimicrobial peptides (AMPs) in the female reproductive tract during pregnancy. This commentary highlights recent advances in the field including those of Itakoa and colleagues who have demonstrated elafin and secretory leukocyte protease inhibitor (SLPI) expression in cervical cells from pregnant women during pregnancy. They suggest that these specific AMPs may be raised in women in true preterm labour. This complements other studies exploring the use cervico-vaginal fluid elafin and other antimicrobial peptides as biomarkers to predict risk of spontaneous preterm birth early in pregnancy. With continued focus on the contribution and regulation of these important small peptides in pregnancy, the potential of AMPs as clinical tools for identifying women most at risk of spontaneous preterm birth should soon be realised.