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

Abstract

, paul t. Seed, evonne c. chin-Smith, Alexandra e. Ridout, Andrew H. Shennan & Rachel M. tribe 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 highrisk 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. Spontaneous preterm birth (sPTB), defined as spontaneous birth prior to 37 weeks of gestation, is a leading cause of neonatal morbidity and mortality. Pathophysiologically, it may be initiated by a number of different and overlapping causative factors including intra-amniotic infection, decidual haemorrhage or senescence, cervical weakness, breakdown of maternal-fetal tolerance, declining progesterone activity 1 and sterile inflammation 2. The culmination of these pathological processes is a process of systemic inflammation, likely similar to the inflammatory pathway associated with early and established term labour (uterine and cervical neutrophil infiltration and release of cytokines, prostaglandins and matrix metalloproteins) 3-5. Thus, increasing attention has been given to the potential use of inflammatory biomarkers to identify women at high risk of subsequent sPTB. These may have potential to guide prevention and/or management strategies, particularly if measurable in early pregnancy and linked to adverse outcome. Natural antimicrobial peptides/proteins (NAPs), the body's rapid 'first defence' response to foreign antigens, are small cationic host defence molecules functioning within the innate immune system. Expressed throughout the female genital tract at epithelial surfaces, their anti-protease action counteract the effect of protease mediated inflammation and tissue destruction 6. NAPs exhibit antibacterial, antiviral and antifungal activity, largely attributed to disruption of microbial membranes 7. Trappin2/elafin (also known as peptidase inhibitor 3) or skin-derived anti-proteinase (SKALP), secretory...

Cervicovaginal microbiota and metabolome predict preterm birth risk in an ethnically diverse cohort

“…CVF measurements of the host response (elafin and HNE) at study entry (early pregnancy), originating from a subset of the data published for the INSIGHT cohort (30), were utilised to assess relationships with microbial community and metabolic composition. Elafin concentrations were significantly increased in women with PCoA group A compared to B and E (Figure 1H), suggesting elafin plus the presence of L. crispatus is protective, and potentially modulated by bacteria or metabolites present within other PCoA communities.…”

“…ROC curves are shown in Figure 5. We did not assess cathelicidin as it was measured only in high risk women and has been reported previously (30). Spontaneous preterm birth is a complex syndrome and although disturbances of the cervicovaginal microbiota are increasingly implicated, any clinical benefit from these observations has yet to be realized.…”

“…During speculum examination cervicovaginal fluid was obtained from the posterior fornix, using a Dacron swab (for metabolite and host defense peptide analysis) and then inserted into 750 µl of standard phosphate-buffered saline solution containing protease inhibitors and EDTA (Complete, Roche Diagnostics GmbH, Germany) (30). Cell-free supernatants were divided into aliquots (∼110 µl) and stored at -80°C until analysis.…”

“…As previously published (30), samples were thawed at room temperature, briefly vortexed and analyzed by ELISA [Trappin2/elafin, HK318; cathelicidin (LL37), HK321; HNE, HK319-02, Hycult, Biotech Cambridge] in duplicate, according to manufacturer's instructions. Samples for elafin measurement were diluted in sample buffer (1∶20 and 1:100 for each sample) to ensure positioning within the standard curve, based on results obtained from a pilot study (27).…”

“…Previously, in pregnant women with a history of sPTB or late miscarriage, we explored the contribution of the maternal host response to risk of preterm birth (27)(28)(29)(30). Host defense peptides (HDPs) including trappin2/elafin (referred here as elafin, a protein regulated by tryptases and inhibitor of human neutrophil elastase, HNE) and cathelicidin (a peptide synthesized by epithelial cells and co-released with HNE from neutrophils) were raised in cervicovaginal fluid (CVF) (27,28,30). The stimuli for these innate host responses were not directly investigated, but we proposed a role for vaginal dysbiosis and suggested that inflammation could contribute to sPTB risk through cervical collagen remodeling.…”