Short and inflamed cervix predicts spontaneous preterm birth (COLIBRI study)

Recent advances in understanding of multifaceted changes in the vaginal microenvironment: implications in vaginal health and therapeutics

The vagina endures multifaceted changes from neonatal to menopausal phases due to hormonal flux, metabolite deposition, and microbial colonization. These features have important implications in women's health. Several pre-factors show dynamic characteristics according to the phases that shift the vaginal microbiota from anaerobes to aerobes which is a hallmark of healthy vaginal environment. These factors include oestrogen levels, glycogen deposition, and vaginal microstructure. In the adult phase, Lactobacillus is highly dominant and regulates pH, adherence, aggregation, immune modulation, synthesis of bacteriocins, and biosurfactants (BSs) which are antagonistic to pathogens. Maternal factors are protective by favouring the colonization of lactobacilli in the vagina in the neonatal phase, which diminishes with age. The dominance of lactobacilli and dysbiosis in the adult phase depends on intrinsic and extrinsic factors in women, which vary between ethnicities. Recent developments in probiotics used against vaginal microbiome dysbiosis have shown great promise in restoring the normal microbiota including preventing the loss of beneficial bacteria. However, further in-depth studies are warranted to ensure long-term protection by probiotics. This review highlights various aspects of the vaginal microenvironment in different phases of growth and diverse ethnicities. Furthermore, it discusses future trends for formulating more effective population-specific probiotics and implications of paraprobiotics and postbiotics as effective therapeutics.

Spontaneous preterm birth: Involvement of multiple feto-maternal tissues and organ systems, differing mechanisms, and pathways

Survivors of preterm birth struggle with multitudes of disabilities due to improper in utero programming of various tissues and organ systems contributing to adult-onset diseases at a very early stage of their lives. Therefore, the persistent rates of low birth weight (birth weight < 2,500 grams), as well as rates of neonatal and maternal morbidities and mortalities, need to be addressed. Active research throughout the years has provided us with multiple theories regarding the risk factors, initiators, biomarkers, and clinical manifestations of spontaneous preterm birth. Fetal organs, like the placenta and fetal membranes, and maternal tissues and organs, like the decidua, myometrium, and cervix, have all been shown to uniquely respond to specific exogenous or endogenous risk factors. These uniquely contribute to dynamic changes at the molecular and cellular levels to effect preterm labor pathways leading to delivery. Multiple intervention targets in these different tissues and organs have been successfully tested in preclinical trials to reduce the individual impacts on promoting preterm birth. However, these preclinical trial data have not been effectively translated into developing biomarkers of high-risk individuals for an early diagnosis of the disease. This becomes more evident when examining the current global rate of preterm birth, which remains staggeringly high despite years of research. We postulate that studying each tissue and organ in silos, as how the majority of research has been conducted in the past years, is unlikely to address the network interaction between various systems leading to a synchronized activity during either term or preterm labor and delivery. To address current limitations, this review proposes an integrated approach to studying various tissues and organs involved in the maintenance of normal pregnancy, promotion of normal parturition, and more importantly, contributions towards preterm birth. We also stress the need for biological models that allows for concomitant observation and analysis of interactions, rather than focusing on these tissues and organ in silos.

Predictive value of cervical cytokine, antimicrobial and microflora levels for pre-term birth in high-risk women

Spontaneous preterm birth (sPTB, delivery <37 weeks gestation), accounts for approximately 10% of births worldwide; the aetiology is multifactorial with intra-amniotic infection being one contributing factor. This study aimed to determine whether asymptomatic women with a history of sPTB or cervical surgery have altered levels of inflammatory/antimicrobial mediators and/or microflora within cervical fluid at 22-24 weeks gestation. External cervical fluid was collected from women with history of previous sPTB and/or cervical surgery at 22-24 weeks gestation (n = 135). Cytokine and antimicrobial peptides were measured on a multiplex platform or by ELISA. qPCR was performed for detection of 7 potentially pathogenic bacterial species. IL-8 and IL-1β levels were lower in women who delivered preterm compared to those who delivered at term (IL-8 P = 0.02; IL-1β P = 0.04). There were no differences in elafin or human beta defensin-1 protein levels between the two groups. Multiple bacterial species were detected in a higher proportion of women who delivered preterm than in those who delivered at term (P = 0.005). Cervical fluid IL-8 and IL-1β and microflora have the potential to be used as biomarkers to predict sPTB in high risk women.

Comparison of Serum and Cervical Cytokine Levels throughout Pregnancy between Preterm and Term Births

Objective  To assess differences in cytokine levels in cervicovaginal fluid (CVF) and serum across trimesters between women with preterm births (PTBs) and full-term births. Study Design  This multicenter study enrolled 302 women with a singleton gestation. CVF and serum cytokines, interleukin 1α (IL-1α), IL-1β, IL-6, IL-8, IL-10, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, and matrix metalloproteinase (MMP)-8, were measured. Women with at least one cytokine assessment and noted PTB status in their medical record were retained in the study ( N  = 272). Data were analyzed using mixed modeling (main effects of PTBs and time/trimester). Results  For the CVF values of IL-6, IL-8, IL-10, TNF-α, and CRP, and serum MMP-8, those who delivered preterm had significantly higher values than the full-term group regardless of trimester. For the serum values of IL-1β, IL-6, and TNF-α, those delivering preterm had significantly lower values than those delivering full-term regardless of trimester. For IL-1β in CVF, the cytokine was significantly higher in the PTB group for second and third trimesters only, relative to the full-term group. Conclusion  For each CVF cytokine that differed by birth status, values were higher for PTB than term, averaged over trimester. Numerous cytokine profiles varied across trimesters in women delivering term versus preterm in both CVF and serum.

The cytokine network in women with an asymptomatic short cervix and the risk of preterm delivery

PROBLEM

To characterize the amniotic fluid (AF) inflammatory-related protein (IRP) network in patients with a sonographic short cervix (SCx) and to determine its relation to early preterm delivery (ePTD).

METHOD OF STUDY

A retrospective cohort study included women with a SCx (≤25 mm; n=223) who had amniocentesis and were classified according to gestational age (GA) at diagnosis and delivery (ePTD <32 weeks of gestation).

RESULTS

(i) In women with a SCx ≤ 22 1/7 weeks, the concentration of most IRPs increased as the cervix shortened; those with ePTD had a higher rate of increase in MIP-1α, MCP-1, and IL-6 concentrations than those delivering later; and (ii) the concentration of most IRPs and the correlation between several IRP pairs were higher in the ePTD group than for those delivering later.

CONCLUSION

Women with a SCx at 16-22 1/7 weeks have a unique AF cytokine network that correlates with cervical length at diagnosis and GA at delivery. This network may aid in predicting ePTD.

Pregnancy Outcomes of Women Admitted to a Tertiary Care Centre with Short Cervix

OBJECTIVE

Our aim was to characterize the management and outcome of women admitted to a tertiary high-risk obstetrics unit with a short cervix (≤25 mm), measured on transvaginal ultrasound (TVS), and to determine the latency period from diagnosis to delivery.

METHODS

A retrospective chart review of women admitted to the High Risk Obstetrics Unit at Sunnybrook Health Sciences Centre between 2005-2011 with an ultrasound-identified short cervix was done.

RESULTS

A total of 110 women admitted for a short cervix between 2005-2011 (N = 56 singletons; N = 54 twin gestations) met the inclusion criteria. The mean latency to delivery was 62.6 days; mean GA at delivery was 33.9 weeks. Following 7 and 14 days of admission, 5.5% and 11.8% of women had delivered, respectively. Preterm birth occurred in 70% of all women. Cervical length was a significant factor in predicting latency among singletons, whereas the length of stay in hospital for activity restriction was not.

CONCLUSIONS

Although many women with a short cervix delivered preterm, only a small proportion delivered within 2 weeks of admission. Although it is not clear whether inpatient management improves the pregnancy outcome, these findings have implications for both patient care and health resources.

Hydrogen Peroxide-Producing Lactobacilli Are Associated With Lower Levels of Vaginal Interleukin-1β, Independent of Bacterial Vaginosis

BACKGROUND

The presence of hydrogen peroxide (H2O2)-producing lactobacilli in the vagina is associated with decreased rates of preterm birth and HIV acquisition. We hypothesize that this is due to immunomodulatory effects of these species.

METHODS

Concentrations of interleukin (IL)-1β, IL-6, IL-8, secretory leukocyte protease inhibitor, and human β-defensin 2 were quantified from vaginal swabs from 4 groups of women: women with and without bacterial vaginosis (BV) by Nugent score, further stratified by detection of H2O2-producing lactobacilli by semiquantitative culture. Ten quantitative polymerase chain reaction assays characterized the presence and quantity of select Lactobacillus and BV-associated species in each group. Levels of immune markers and bacteria were compared between the 4 groups using analysis of variance, Kruskal-Wallis, Mann-Whitney U, or χ tests.

RESULTS

Swabs from 110 women from 4 groups were included: 26 had a normal Nugent score (BV-), and no H2O2-producing lactobacilli detected (H2O2-); 47 were BV-, H2O2+; 27 BV+, H2O2-; and 10 BV+, H2O2+. The groups were similar in age, marital status, and reproductive history, but not ethnicity: the BV-, H2O2- group had more white participants (P = 0.02). In women with and without BV, IL-1β was lower in the H2O2+ groups. Human β-defensin 2 was lowest in BV+ H2O2- women and highest in BV-, H2O2-. Secretory leukocyte protease inhibitor was lower in women with BV and did not differ by the presence of H2O2-producing lactobacilli. In regression analysis, higher quantities of Lactobacillus crispatus were associated with lower quantities of IL-1β. Detection and quantity of BV-associated species by quantitative polymerase chain reaction was significantly different between women with and without BV, but not between women with and without H2O2-producing lactobacilli within those groups.

CONCLUSIONS

The presence of H2O2-producing lactobacilli is associated with lower levels of some vaginal proinflammatory cytokines, even in women with BV.

Prediction of impending preterm delivery based on sonographic cervical length and different cytokine levels in cervicovaginal fluid in preterm labor

AIMS

The aim of this study was to determine whether cervicovaginal interleukin (IL)-1β, IL-6 and IL-8 levels, and cervical length, alone or in combination, could predict impending preterm delivery in women with preterm labor and intact membranes.

MATERIAL AND METHODS

Cervicovaginal swab samples for IL-1β, IL-6, and IL-8 assays were taken from 136 consecutive women with preterm labor (23-34 weeks) before the transvaginal ultrasonography examination to measure cervical length. The primary outcome measurement was spontaneous preterm delivery within 7 days of sampling.

RESULTS

Spontaneous preterm delivery within 7 days occurred in 28.6% (39/136) of patients. Receiver-operator characteristic (ROC) curves indicated that cervical length (P < 0.001), cervicovaginal IL-6 (P < 0.001) and IL-8 (P = 0.014), but not IL-1β, could predict delivery within 7 days. According to the logistic regression analysis, high cervicovaginal IL-8 (P = 0.008) and IL-6 (P = 0.038) levels and short cervical length (P < 0.001) were significantly associated with delivery within 7 days, even after controlling for baseline variables. A combination of cervix length and cervicovaginal IL-8 increased the specificity of detecting delivery within 7 days to 92.8%, which was superior to either test alone (P < 0.001), but the sensitivity was only 56.4%.

CONCLUSION

In women with preterm labor, among the parameters assessed, cervicovaginal IL-6 and IL-8 and cervical length are the most important parameters in predicting impending preterm delivery. A combination of cervix length and cervicovaginal IL-8 appeared to be the best for predicting impending preterm delivery, but the relatively low sensitivity of this test may limit its clinical usefulness.

Sterile intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix: prevalence and clinical significance

OBJECTIVE

To determine the frequency and clinical significance of sterile and microbial-associated intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix.

METHODS

Amniotic fluid (AF) samples obtained by transabdominal amniocentesis from 231 asymptomatic women with a sonographic short cervix [cervical length (CL) ≤25 mm] were analyzed using cultivation techniques (for aerobic and anaerobic as well as genital mycoplasmas) and broad-range polymerase chain reaction (PCR) coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). The frequency and magnitude of intra-amniotic inflammation [defined as an AF interleukin (IL)-6 concentration ≥2.6 ng/mL], acute histologic placental inflammation, spontaneous preterm delivery (sPTD), and the amniocentesis-to-delivery interval were examined according to the results of AF cultures, PCR/ESI-MS and AF IL-6 concentrations.

RESULTS

Ten percent (24/231) of patients with a sonographic short cervix had sterile intra-amniotic inflammation (an elevated AF IL-6 concentration without evidence of microorganisms using cultivation and molecular methods). Sterile intra-amniotic inflammation was significantly more frequent than microbial-associated intra-amniotic inflammation [10.4% (24/231) versus 2.2% (5/231); p < 0.001]. Patients with sterile intra-amniotic inflammation had a significantly higher rate of sPTD <34 weeks of gestation [70.8% (17/24) versus 31.6% (55/174); p < 0.001] and a significantly shorter amniocentesis-to-delivery interval than patients without intra-amniotic inflammation [median 35, (IQR: 10-70) versus median 71, (IQR: 47-98) days, (p < 0.0001)].

CONCLUSION

Sterile intra-amniotic inflammation is more common than microbial-associated intra-amniotic inflammation in asymptomatic women with a sonographic short cervix, and is associated with increased risk of sPTD (<34 weeks). Further investigation is required to determine the causes of sterile intra-amniotic inflammation and the mechanisms whereby this condition is associated with a short cervix and sPTD.