Compartmentalized Innate Immune Response of Human Fetal Membranes against Escherichia coli Choriodecidual Infection

An infectious process into the uterine cavity represents a major endangered condition that compromises the immune privilege of the maternal-fetal unit and increases the risk for preterm birth (PTB) and premature rupture of membranes (PROM). Fetal membranes are active secretors of antimicrobial peptides (AMP), which limit bacterial growth, such as Escherichia coli. Nevertheless, the antibacterial responses displayed by chorioamniotic membranes against a choriodecidual E. coli infection have been briefly studied. The objective of this research was to characterize the profile of synthesis, activity, and spatial distribution of a broad panel of AMPs produced by fetal membranes in response to E. coli choriodecidual infection. Term human chorioamniotic membranes were mounted in a two independent compartment model in which the choriodecidual region was infected with live E. coli (1 × 10⁵ CFU/mL). Amnion and choriodecidual AMP tissue levels and TNF-α and IL-1β secretion were measured by the enzyme-linked immunosorbent assay. The passage of bacterium through fetal membranes and their effect on structural continuity was followed for 24 h. Our results showed that E. coli infection caused a progressive mechanical disruption of the chorioamniotic membranes and an activated inflammatory environment. After the challenge, the amnion quickly (2-4 h) induced production of human beta defensins (HBD)-1, HBD-2, and LL-37. Afterwards (8-24 h), the amnion significantly produced HBD-1, HBD-2, HNP-1-3, S100A7, sPLA2, and elafin, whereas the choriodecidua induced LL-37 synthesis. Therefore, we noticed a temporal- and tissue-specific pattern regulation of the synthesis of AMPs by infected fetal membranes. However, fetal membranes were not able to contain the collagen degradation or the bacterial growth and migration despite the battery of produced AMPs, which deeply increases the risk for PTB and PROM. The mixture of recombinant HBDs at low concentrations resulted in increased bactericidal activity compared to each HBD alone in vitro, encouraging further research to study AMP combinations that may offer synergy to control drug-resistant infections in the perinatal period.

Identification of anti-microbial peptides and traces of microbial DNA in infrainfundibular compartments of human scalp terminal hair follicles

BACKGROUND

The upper follicular compartment, a well-known reservoir of cutaneous microbiota, constitutes a space for intensive cross-barrier dialogue. The lower follicle comprises the bulb and bulge, structures with relative immune-privileged status, crucial for physiological cycling, and widely considered to be microbial-free.

OBJECTIVES

Following our initial immunohistochemical screening for regulatory cytokines and defensin expression in anagen hair follicles, we aimed to confirm our results with a follow-up ELISA investigation. We postulated that exposure to microbial components may trigger expression, and thus opted to investigate microbial presence in this area.

MATERIALS & METHODS

We performed immunohistochemical staining for selected cytokines and antimicrobial peptides, and Gram and Giemsa staining on tissue sections from healthy individuals. Based on ELISA analyses, we confirmed a marked presence of IL-17A- and HBD2 in infrainfundibular compartments from plucked anagen hair follicles of 12 individuals (six females, six males; frontal and occipital scalp sites). 16S rRNA sequencing on microbial DNA extracted from lower follicles, as well as fluorescence in situ hybridization (FISH) were applied to explore bacterial presence in the infrainfundibular compartments.

RESULTS

16S rRNA sequencing yielded reproducible data of bacterial presence in infrainfundibular compartments of plucked scalp follicles; Lawsonella clevelandensis, Staphylococcaceae and Propionibacteriaceae were the most abundant bacteria. Also, FISH revealed biofilm structures formed by Cutibacterium acnes (formerly Propionibacterium acnes) and Staphylococcus sp. below the infundibulum.

CONCLUSION

As the skin microbiome largely influences the local immune system, the presence of bacteria in proximity to follicular immune-privileged areas may be of relevance to hair cycling in health and disease.

Maternal stress, low cervicovaginal β-defensin, and spontaneous preterm birth

Background

Spontaneous preterm birth (sPTB) is a major contributor to infant mortality and its etiology remains poorly understood. Host immunity and maternal stress may play a role in the pathogenesis of sPTB but mechanisms are poorly delineated. Antimicrobial proteins in the cervicovaginal space, such as beta defensins, modulate immune responses to bacteria and have been shown to modulate the risk of sPTB from non-optimal microbiota. While stress is known to induce immunological changes, no study has examined the interplay between maternal stress and the immune response in association with sPTB.

Objectives

Our objectives were to determine whether psychosocial stress was associated with a mediator of the immune system in the cervicovaginal space, beta defensin-2, and to examine the combined impact of high stress and low cervicovaginal beta defensin-2 levels on the odds of sPTB.

Study Design

From the Motherhood & Microbiome cohort study (n=2000), we performed a secondary, nested case-control study, frequency matched by race/ethnicity, of 519 pregnant women (110 sPTB and 409 term). Stress and cervicovaginal beta defensin-2 levels were measured at 16-20 weeks of gestation. Stress was dichotomized at a score of 30 on Cohen's Perceived Stress Scale (PSS-14). We measured cervicovaginal beta defensin-2 levels with ELISA and dichotomized at the median. We modeled associations of high stress and low cervicovaginal beta defensin-2 levels using multivariable logistic regression. We also compared the proportion of women with high stress and low cervicovaginal beta defensin-2 levels among women with spontaneous preterm and term births using Chi-Square tests. We modeled adjusted associations of stress and cervicovaginal beta defensin-2 levels with odds of sPTB using logistic regression.

Results

The majority of the study population was non-Hispanic black (72.8%), insured by Medicaid (51.1%), and had a PSS-14 score < 30 (80.2%). High stress was associated with reduced adjusted odds of low beta defensin-2 levels (aOR 0.63, 95% CI: 0.38 -0.99). In a model adjusted for race and smoking, both high stress (aOR 1.72, 95% CI: 1.03-2.90) and low beta defensin-2 (aOR 1.58, 95% CI: 1.004-2.49) were associated with increased odds of sPTB. We then built a model of the four possible combinations of low and high stress and low and high beta defensin-2 levels with the odds of sPTB. Women with either high stress (aOR 1.37, 95% CI: 0.68 - 2.78) or low beta defensin-2 (aOR 1.40, 95% CI: 0.83-2.34), had slightly elevated but not significantly increased odds of sPTB compared to women with neither exposure. However, women with both high stress and low beta defensin-2 had significantly elevated odds of sPTB compared to women with neither exposure (aOR 3.16, 95 % CI: 1.46 - 6.84).

Conclusion

High perceived stress and low cervicovaginal beta defensin-2 levels are associated with higher odds of sPTB, and when present concurrently, they result in the highest odds of sPTB in a largely non-Hispanic black cohort. Our findings warrant further work to examine social determinants of health and the host cervicovaginal immune responses that may modulate the pathogenesis of sPTB.