Jorge Beltrán-Montoya

Secretions of Interleukin-1β and Tumor Necrosis Factor α by Whole Fetal Membranes Depend on Initial Interactions of Amnion or Choriodecidua with Lipopolysaccharides or Group B Streptococci

Abstract The present study evaluated the secretions of interleukin (IL)-1β and tumor necrosis factor (TNF) α by fetal membranes stimulated with group B streptococci (GBS) and lipopolysaccharide (LPS). The aim was to evaluate the initial response of full-thickness membranes to the microbial insult using an in vitro experimental model that allowed testing of the individual contributions of amnion and choriodecidua to stimulation. Full-thickness membranes were obtained after delivery by elective cesarean section from women at 37–40 wk of gestation without evidence of active labor. The membranes were mounted in Transwell devices, physically separating the upper and lower chambers. The LPS (500 ng/ml) or GBS (1 × 106 colony-forming units/ml) was added to either the amniotic or choriodecidual surface, and accumulation of IL-1β and TNFα were measured in both compartments using a specific ELISA. Fetal membranes followed different patterns of secretion of proinflammatory cytokines that depended on the side to which the stimulus was added or the nature of the stimulus itself. The TNFα was secreted by amnion and choriodecidua in the presence of LPS or GBS, and stimulation with GBS induced a greater synthesis of IL-1β than did stimulation with LPS. Choriodecidual tissue was more responsive than amniotic tissue, and this response tended to be higher even when the stimulation was only on the amniotic side. However, the amnion plays an active role in recognizing LPS or GBS, contributing a significant amount of TNFα. Thus, cooperative and bidirectional communications occur between amnion and choriodecidua in response to bacterial products, which include intermembranous cytokine traffic and signaling between tissues.

Air pollution, inflammation and preterm birth: A potential mechanistic link

Preterm birth is a public health issue of global significance, which may result in mortality during the perinatal period or may lead to major health and financial consequences due to lifelong impacts. Even though several risk factors for preterm birth have been identified, prevention efforts have failed to halt the increasing rates of preterm birth. Epidemiological studies have identified air pollution as an emerging potential risk factor for preterm birth. However, many studies were limited by study design and inadequate exposure assessment. Due to the ubiquitous nature of ambient air pollution and the potential public health significance of any role in causing preterm birth, a novel focus investigating possible causal mechanisms influenced by air pollution is therefore a global health priority. We hypothesize that air pollution may act together with other biological factors to induce systemic inflammation and influence the duration of pregnancy. Evaluation and testing of this hypothesis is currently being conducted in a prospective cohort study in Mexico City and will provide an understanding of the pathways that mediate the effects of air pollution on preterm birth. The important public health implication is that crucial steps in this mechanistic pathway can potentially be acted on early in pregnancy to reduce the risk of preterm birth.

Placental blood leukocytes are functional and phenotypically different than peripheral leukocytes during human labor

Rupture of the fetal membranes during human labor is associated with an inflammatory process localized to the maternal-fetal interface. There is evidence that specific leukocytes subsets are attracted to the choriodecidua, and that after homing they condition a local inflammatory microenvironment, possibly being directly involved in rupture of the membranes. In this study our aim was to compare the phenotypes and function of leukocytes located in the placental intervillous blood with peripheral leukocytes obtained before or after labor, including expression of modulators of inflammation in these cells. Flow cytometry revealed that the proportion of CD14(+) cells is increased in intervillous blood, suggesting the participation of monocytes/macrophages during labor. Real time qRT-PCR showed that at term gestation and particularly during labor, placental blood leukocytes adopt a different expression pattern of pro-inflammatory cytokines than leukocytes in peripheral blood, including IL-1beta and IL-1RA. During labor, both placental and peripheral leukocytes increase their secretion of matrix metalloproteinase-9. Moreover, we showed that placental leukocytes respond differently than peripheral leukocytes to bacterial lipopolysaccharide, secreting differential amounts of TNF-alpha, IL-1beta and IL-6. Finally, a preliminary proteomic characterization of placental leukocytes revealed a significantly higher number of individual proteins than in peripheral leukocytes. Our results support the existence of selective subsets of leukocytes recruited to the maternal-fetal interface that may participate in the triggering of parturition.

Incubation of human chorioamniotic membranes with Candida albicans induces differential synthesis and secretion of interleukin‐1β, interleukin‐6, prostaglandin E2, and 92 kDa type IV collagenase

Ascendant colonization of pathogenic microorganisms from the vagina to the uterus is strongly associated to preterm labour and premature rupture of membranes. This study evaluated the secretion of interleukin (IL)‐1β, tumour necrosis factor (TNF)α, IL‐6, prostaglandin E2 (PGE2), and metalloproteinases 9 and 2 by the human chorioamnion stimulated with Candida albicans. Chorioamniotic membranes were obtained after delivery by elective Cesarean section from women at 37–40 weeks of gestation without evidence of active labour. The membranes were mounted in Transwell devices that form two independent compartments, which allow testing the individual responses and contributions of the amnion and choriodecidua. One million CFU ml−1 of C. albicans was added to either the amniotic or choriodecidual surface and secretions of the markers were measured in both compartments using specific enzyme‐linked immunosorbent assay and zymography. Fetal membranes followed different secretion patterns of proinflammatory cytokines depending on the side to which the stimulus was applied. IL‐1β was produced in higher amounts in the presence of C. albicans when applied to the choriodecidual side; TNFα and IL‐6 secretion did not change in either the amnion or choriodecidual region. PGE2 synthesis depicted a different pattern, the amniotic tissue was more responsive than the choriodecidual tissue, and this response tended to be higher even when only the amniotic side was stimulated. Matrix metalloproteinases (MMP)‐9 increased after stimulation, being the choriodecidua its main source. Selective stimulation with C. albicans induced a differential secretion of IL‐1β, PGE2, and MMP‐9, resulting from a cooperative and bidirectional communication between the amnion and the choriodecidua.

Association between adiposity and inflammatory markers in maternal and fetal blood in a group of Mexican pregnant women

In the present pilot study, we evaluated the effect of maternal adiposity on the plasma concentration of adipocytokines in pregnant women and their newborns. Twenty patients with term gestations without labour were initially selected by pregestational BMI and then classified into two study groups (n 10 each), according to their median value of adiposity (total body fat). Concentrations of TNF-α, IL-1β, IL-6, leptin and adiponectin in plasma of maternal peripheral blood and fetal cord blood were measured and correlated to maternal adiposity. Maternal adiposity showed a significant negative correlation with fetal adiponectin (r - 0·587, P = 0·01) and IL-6 (r - 0·466, P = 0·05), a significant positive correlation with maternal leptin (r 0·527, P = 0·02) and no correlation with TNF-α or IL-1β. Adiponectin was higher in fetal plasma than in maternal plasma (P = 0·043), but significantly lower in newborns from women with high adiposity than in newborns from women with low adiposity (P = 0·040). Our results suggest that fetuses from obese women may be less able to control inflammation, due to lower circulating anti-inflammatory adipocytokines, which could limit their optimal development or even increase the risk of abortion or preterm labour.

Choriodecidual cells from term human pregnancies show distinctive functional properties related to the induction of labor.

Human parturition is associated with an intrauterine pro‐inflammatory environment in the choriodecidua. Evidence that some mediators of this signaling cascade also elicit responses leading to labor prompted us to characterize the cellular sources of these mediators in the human choriodecidua.

Matrix Metalloproteinase-3 (MMP-3) Is an Endogenous Activator of the MMP-9 Secreted by Placental Leukocytes: Implication in Human Labor.

Background The activity of matrix degrading enzymes plays a leading role in the rupture of the fetal membranes under normal and pathological human labor, and matrix metalloproteinase-9 (MMP-9) it is considered a biomarker of this event. To gain further insight into local MMP-9 origin and activation, in this study we analyzed the contribution of human placental leukocytes to MMP-9 secretion and explored the local mechanisms of the pro-enzyme activation. Methods Placental blood leukocytes were obtained from women at term gestation without labor and maintained in culture up to 72 h. MMP-9 activity in the culture supernatants was determined by zymography and using a specific substrate. The presence of a potential pro-MMP-9 activator in the culture supernatants was monitored using a recombinant biotin-labeled human pro-MMP-9. To characterize the endogenous pro-MMP-9 activator, MMP-1, -3, -7 and -9 were measured by multiplex assay in the supernatants, and an inhibition assay of MMP-9 activation was performed using an anti-human MMP-3 and a specific MMP-3 inhibitor. Finally, production of MMP-9 and MMP-3 in placental leukocytes obtained from term pregnancies with and without labor was assessed by immunofluorescence. Results Placental leukocytes spontaneously secreted pro-MMP-9 after 24 h of culture, increasing significantly at 48 h (P≤0.05), when the active form of MMP-9 was detected. Culture supernatants activated the recombinant pro-MMP-9 showing that placental leukocytes secrete the activator. A significant increase in MMP-3 secretion by placental leukocytes was observed since 48 h in culture (P≤0.05) and up to 72 h (P≤0.001), when concentration reached its maximum value. Specific activity of MMP-9 decreased significantly (P≤0.005) when an anti-MMP-3 antibody or a specific MMP-3 inhibitor were added to the culture media. Placental leukocytes from term labor produced more MMP-9 and MMP-3 compared to term non-labor cells. Conclusions In this work we confirm that placental leukocytes from human term pregnancies are able to secrete large amounts of MMP-9, and that the production of the enzyme it is enhanced by labor. We also demonstrate for the first time that endogenous MMP-3 plays a major role in MMP-9 activation process. These findings support the contribution of placental leukocytes to create the collagenolytic microenvironment that induces the rupture of the fetal membranes during human labor.