Interleukin-8 potentiates the effect of interleukin-1-induced uterine contractions

The Role of the NLRP3 Inflammasome in the Molecular and Biochemical Mechanisms of Cervical Ripening: A Comprehensive Review

The uterine cervix is one of the key factors involved in ensuring a proper track of gestation and labor. At the end of the gestational period, the cervix undergoes extensive changes, which can be summarized as a transformation from a non-favorable cervix to one that is soft and prone to dilation. During a process called cervical ripening, fundamental remodeling of the cervical extracellular matrix (ECM) occurs. The cervical ripening process is a derivative of many interlocking and mutually driving biochemical and molecular pathways under the strict control of mediators such as inflammatory cytokines, nitric oxide, prostaglandins, and reactive oxygen species. A thorough understanding of all these pathways and learning about possible triggering factors will allow us to develop new, better treatment algorithms and therapeutic goals that could protect women from both dysfunctional childbirth and premature birth. This review aims to present the possible role of the NLRP3 inflammasome in the cervical ripening process, emphasizing possible mechanisms of action and regulatory factors.

Integrating single-cell RNA sequencing with spatial transcriptomics reveals an immune landscape of human myometrium during labour

BACKGROUND

The transition of the myometrium from a quiescent to a contractile state during labour is known to involve inflammation, which is characterized by the infiltration of immune cells and the secretion of cytokines. However, the specific cellular mechanisms underlying inflammation in the myometrium during human parturition are not yet fully understood.

METHODS

Through the analysis of transcriptomics, proteomics, and cytokine arrays, the inflammation in the human myometrium during labour was revealed. By performing single-cell RNA sequencing (scRNA-seq) and spatiotemporal transcriptomic (ST) analyses on human myometrium in term in labour (TIL) and term in non-labour (TNL), we established a comprehensive landscape of immune cells, their transcriptional characteristics, distribution, function and intercellular communications during labour. Histological staining, flow cytometry, and western blotting were applied to validate some results from scRNA-seq and ST.

RESULTS

Our analysis identified immune cell types, including monocytes, neutrophils, T cells, natural killer (NK) cells and B cells, present in the myometrium. TIL myometrium had a higher proportion of monocytes and neutrophils than TNL myometrium. Furthermore, the scRNA-seq analysis showed an increase in M1 macrophages in TIL myometrium. CXCL8 expression was mainly observed in neutrophils and increased in TIL myometrium. CCL3 and CCL4 were principally expressed in M2 macrophages and neutrophils-6, and decreased during labour; XCL1 and XCL2 were specifically expressed in NK cells, and decreased during labour. Analysis of cytokine receptor expression revealed an increase in IL1R2, which primarily expressed in neutrophils. Finally, we visualized the spatial proximity of representative cytokines, contraction-associated genes, and corresponding receptors in ST to demonstrate their location within the myometrium.

CONCLUSIONS

Our analysis comprehensively revealed changes in immune cells, cytokines, and cytokine receptors during labour. It provided a valuable resource to detect and characterize inflammatory changes, yielding insights into the immune mechanisms underlying labour.

Signaling Pathways Regulating Human Cervical Ripening in Preterm and Term Delivery

At the end of gestation, the cervical tissue changes profoundly. As a result of these changes, the uterine cervix becomes soft and vulnerable to dilation. The process occurring in the cervical tissue can be described as cervical ripening. The ripening is a process derivative of enzymatic breakdown and inflammatory response. Therefore, it is apparent that cervical remodeling is a derivative of the reactions mediated by multiple factors such as hormones, prostaglandins, nitric oxide, and inflammatory cytokines. However, despite the research carried out over the years, the cellular pathways responsible for regulating this process are still poorly understood. A comprehensive understanding of the entire process of cervical ripening seems crucial in the context of labor induction. Greater knowledge could provide us with the means to help women who suffer from dysfunctional labor. The overall objective of this review is to present the current understanding of cervical ripening in terms of molecular regulation and cell signaling.

Impact of Oxidative Stress on Molecular Mechanisms of Cervical Ripening in Pregnant Women

Uterine cervix is one of the essential factors in labor and maintaining the proper course of pregnancy. During the last days of gestation, the cervix undergoes extensive changes manifested by transformation from a tight and rigid to one that is soft and able to dilate. These changes can be summarized as “cervical ripening”. Changes in the cervical tissue can be referred to as remodeling of the extracellular matrix. The entire process is the result of a close relationship between biochemical and molecular pathways, which is strictly controlled by inflammatory and endocrine factors. When the production of reactive oxygen species exceeds the antioxidant capacity, oxidative stress occurs. A physiologic increase of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is observed through pregnancy. ROS play important roles as second messengers in many intracellular signaling cascades contributing to the course of gestation. This review considers their involvement in the cervical ripening process, emphasizing the molecular and biochemical pathways and the clinical implications.

Targeting bromodomain-containing proteins to prevent spontaneous preterm birth

Preterm birth is a global healthcare challenge. Spontaneous preterm birth (sPTB) is commonly caused by inflammation, yet there are currently no effective therapies available. The Bromodomain and Extra-Terminal motif (BET) proteins, Bromodomain-containing protein (Brd) 2 (Brd2), Brd3 and Brd4 regulate inflammation in non-gestational tissues. The roles of Brd2-4 in human pregnancy are unknown. Using human and mouse models, the present study has identified the Brd proteins part of the process by which inflammation induces parturition. Using human clinical samples, we demonstrate that labor and infection increase the expression of Brds in the uterus and fetal membranes. In primary human myometrial, amnion and decidual cells, we found that global Brd protein inhibition, as well as selective inhibition of Brds, suppressed inflammation-induced expression of mediators involved in myometrial contractions and rupture of fetal membranes. Importantly, studies in the mouse model demonstrate that the pan-Brd inhibitor JQ1 reduced intrauterine inflammation induced by bacterial endotoxin LPS as well as decreasing the effectiveness of LPS to induce parturition. These results implicate BET proteins as novel therapeutic targets for reducing inflammation associated with spontaneous preterm labor.

Inhibition of GPR91 Reduces Inflammatory Mediators Involved in Active Labor in Myometrium

Results

GPR91 mRNA expression was significantly higher in myometrium from women during term spontaneous labor compared to no labor. Likewise, in mice, GPR91 mRNA expression was significantly upregulated in myometrium during inflammation-induced preterm labor compared to preterm no labor. In myometrial cells, IL1B and TNF significantly increased GPR91 mRNA expression. Knockdown of GPR91 by siRNA in myometrial cells significantly suppressed the secretion and/or expression of IL1B- and TNF-induced proinflammatory cytokines (GM-CSF, IL1A, IL1B, and IL6) and chemokines (CXCL8 and CCL2), myometrial contractility (expression of the contraction-associated proteins PTGFR and CX43, secretion of the uterotonic PGF_2α, and in situ collagen gel contraction), and the transcription factor NF-κB.

Conclusion

Our findings demonstrate that GPR91 is involved in the genesis of proinflammatory and prolabor mediators induced by IL1B or TNF and collectively suggest that GPR91 may contribute to augmentation of the labor processes.

Myometrial tumor necrosis factor-α receptors increase with gestation and labor and modulate gene expression through mitogen-activated kinase and nuclear factor-κB

Previously, we found that myometrial tumor necrosis factor-α (TNF-α) messenger RNA (mRNA) expression did not increase with preterm or term labor. To further investigate the role of TNF-α in human labor, we studied TNF-α receptor (TNFR1A and B) expression, regulation, and associated intracellular signaling pathways in human myometrial samples obtained both before and after the onset of labor and in primary cultures of uterine smooth muscle cells (USMCs). We found that the mRNA expression of both receptors increased with advancing gestation and labor and protein levels of TNFR1B were significantly higher in term laboring myometrial samples than in nonlabor controls. Tumor necrosis factor- treatment of USMCs activated all mitogen-activated protein kinase (MAPK) subtypes and nuclear factor κ-B (NF-κB). The TNF-α induced increases in the expression of TNFR1B and prostaglandin H synthase type 2 were reduced by inhibitors of NF-κB and MAPKs, respectively. The TNF-α induced increase in interleukin 8 (IL-8) appeared to be independent of MAPK and NF-κB pathway. These data suggest that the uterus may become more sensitive to the action of TNF-α with advancing gestation and labor and that TNF-α acts via MAPK and NF-κB to promote labor-associated gene expression.

Pro-labour myometrial gene expression: are preterm labour and term labour the same?

Preterm labour (PTL) is the most important cause of neonatal morbidity and mortality. While some causes have been identified, the mechanisms involved remain elusive. This study investigates whether term labour (TL) is an appropriate model for PTL by examining pro-labour gene expression, using quantitative rtPCR, and protein synthesis, using Western analysis, in preterm and term myometrial samples obtained from the upper and lower uterine segments before and after the onset of labour. In the lower segment, the levels of prostaglandin H synthase type-2 (PGHS-2), interleukin-1beta (IL-1beta), IL-6 and IL-8 mRNA expression were significantly higher in TL compared with PTL samples. Compared with non-labour controls, the expression of IL-1beta and IL-8 mRNA was increased in both PTL and TL samples and the expression of PGHS-2 and IL-6 mRNA was increased in TL samples only. In the upper segment, there were no differences between PTL and TL samples and the mRNA expression of PGHS-2 and IL-1beta was increased in TL compared with term no labour samples. No effect of PTL or TL was seen on either oxytocin receptor or connexin-43 mRNA expression or protein levels. The multiple regression analysis and studies in primary cultures of uterine myocytes suggest that the inflammatory cytokines, IL-1beta and tumour necrosis factor-alpha, are the most important regulators of PGHS-2 and IL-8. Our data show that preterm and term labouring myometrium are significantly different and that the most marked labour-induced changes in gene expression are in the lower segment. These changes may occur in response to the release of inflammatory cytokines by the labour-associated inflammatory infiltration.

Cytokine networks and the regulation of uterine function in pregnancy and parturition

Complex cytokine networks play an important role in a wide range of reproductive and pregnancy related processes. Here, we review the current knowledge concerning the impact of cytokines on uterine physiology and pathophysiology. Cytokines influence a range of uterine functions during the menstrual cycle, implantation, pregnancy and labour. The synergistic interactions between individual cytokines are intricate and dynamic, and modulated by pregnancy hormones. It is not surprising therefore, that perturbations to cytokine signalling are associated with adverse pregnancy outcomes, such as miscarriage, pre-eclampsia, preterm labour and foetal brain injury. Further insight into the complexity of cytokine networks will be required to develop novel therapeutic strategies for the treatment of cytokine imbalances in pregnancy.

The mitogen-activated protein kinase dependent expression of prostaglandin H synthase-2 and interleukin-8 messenger ribonucleic acid by myometrial cells: the differential effect of stretch and interleukin-1{beta}

Infection and uterine stretch are the common causes of preterm labor. IL-1beta plays a key role in infection-induced preterm labor and increases prostaglandin H synthase 2 (PGHS-2) and IL-8 expression. We have shown that mechanical stretch of uterine myocytes in vitro up-regulates the expression of PGHS-2 and IL-8. In this study, we tested the hypotheses that both IL-1beta and mechanical stretch increase the myometrial expression of PGHS-2 and IL-8 via MAPK activation and that their effects are synergistic. MAPK activation was assessed in myocytes obtained from pregnant women undergoing cesarean section before the onset of labor after exposure to IL-1beta and stretch either alone or in combination. Specific inhibitors of ERK, p38, and c-Jun N-terminal kinase were used to define the role of each in the increased expression of PGHS-2 and IL-8 mRNA. We found that both IL-1beta and stretch activated all three MAPK subtypes but that they had no synergistic effect. The inhibitor studies showed that stretch-induced increases in both PGHS-2 and IL-8 mRNA expression were ERK1/2 and p38 dependent and that IL-1beta-induced increases of PGHS-2 mRNA expression were also ERK1/2 and p38 dependent, but those of IL-8 were dependent only on ERK1/2 activation. These data show that exposure of human uterine myocytes to both stretch and IL-1beta activates the MAPK system, which is responsible for the increase in PGHS-2 and IL-8 mRNA expression. We found no evidence of a synergistic effect of IL-1beta and stretch on myometrial expression of PGHS-2 and IL-8 mRNA.

Uterine motor alterations and estrous cycle disturbances associated with colonic inflammation in the rat

The impact of colitis on uterine contractility and estrous cycle was investigated after intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats. Colitis severity was assessed by macroscopic damage scoring (MDS) 4 days after TNBS, and myeloperoxidase (MPO) activity was measured in both colon and uterus of control and colitic rats. Estrous cycle stages were determined by vaginal smears and histology, and uterine contractility was assessed in vitro on longitudinal and circular strips. In control rats, uterine MPO activity varied markedly during the cycle and peaked around estrus. In rats with moderate colitis [MDS < 5, 3.1 ± 0.2 (mean ± SE)], uterine MPO decreased by 61% compared with estrus control, without disruption of the cycle. Frequency of spontaneous contractions was reduced by 32% in circular muscle. Contractile responses to KCl and carbachol were not affected, whereas maximal response to oxytocin decreased by 47% in the longitudinal muscle. In rats with severe colitis (MDS > 5, 6.0 ± 0.2), uterine MPO was reduced by 96% and estrous cycle was disrupted. Spontaneous contractility was impaired in circular strips, and a 39% decrease in the contraction frequency occurred in the longitudinal strips. Circular strips did not contract to KCl or carbachol; however, longitudinal strips had maximal responses to KCl, carbachol, and oxytocin reduced by 36%, 27%, and 46%, respectively. Estrogen replacement protected the uterine responses to carbachol in colitic rats, whereas oxytocin responses remained depressed. These data indicate that colonic inflammation can influence both spontaneous and evoked uterine contractility, in relation to estrous cycle disturbances, impaired estradiol production, and functional alterations of myometrial cells.

Synthesis of immune modulators by smooth muscles

The primary function of smooth muscle cells is to contract and alter the stiffness or diameter of hollow organs such as blood vessels, the airways and the gastrointestinal and urogenital tracts. In addition to purely structural functions, smooth muscle cells may play important metabolic roles, particularly in various inflammatory responses. In cell culture, these cells have been shown to be metabolically dynamic, synthesizing and secreting extracellular matrix proteins, glycosaminoglycans and a wide variety of cell-cell signaling proteins, such as interleukins, chemokines and peptide growth factors. Secreted cell signaling proteins participate in the inflammatory response of smooth muscle-containing organs, and some can also stimulate smooth muscle migration, proliferation and contraction. The cellular signaling pathways controlling synthesis of these signaling proteins are similar to those used by cells mediating innate immunity and may contribute to pathogenesis of diverse diseases including atherosclerosis, asthma, inflammatory bowel diseases and preterm labor. Appreciating the role of smooth muscle cells in these diseases may lead to better understanding of the beneficial effects of anti-inflammatory drugs as well as identification of new targets for anti-inflammatory therapy.

Correlation of local interleukin-1beta levels with specific IgA response against Gardnerella vaginalis cytolysin in women with bacterial vaginosis

PROBLEM

Mucosal immune system activation may represent a critical determinant of adverse sequelae correlated with bacterial vaginosis, as HIV sexual transmission, upper genital tract infections, cervicitis, endometritis, postsurgical infections, and adverse pregnancy outcomes as preterm delivery (PTD), low birth weight (LBW).

METHOD OF STUDY

Levels of interleukin-1beta (IL-1beta), anti-Gardnerella vaginalis hemolysin (Gvh) IgA, pH, Nugent score, and number of leukocytes were measured in vaginal fluids of 60 fertile women with bacterial vaginosis and of 64 healthy controls.

RESULTS

Vaginal IL-1beta levels were nearly 13-fold higher in women with bacterial vaginosis (BV) and were associated with anti-Gvh IgA response. IL-1beta was positively correlated with leukocyte counts in the smear both in healthy and bacterial vaginosis positive women.

CONCLUSIONS

Induction of the proinflammatory cytokine IL-1beta may be a necessary event to elicit an innate immune response to control anaerobic genital tract infections. High levels of vaginal IL-1beta are associated with mounting of an antigen-specific mucosal immune response in women with bacterial vaginosis. Parallel induction of innate and adaptive immune response may be associated with protection from ascent of micro-organisms to the upper genital tract, and from acquiring viral infection through the vaginal tract.

Uterine chemokines in reproductive physiology and pathology

PROBLEM

Chemokines are increasingly recognized as important regulators of uterine function.

METHODS OF STUDY

The following is a review of uterine chemokines, especially monocyte chemotactic protein (MCP)-1, interleukin (IL)-8, and regulated-upon-activation normal-T-cell-expressed and -secreted (RANTES) protein, in reproductive physiology and pathology.

RESULTS

It is increasingly clear that IL-8, MCP-1, RANTES and their receptors are produced by endometrial, myometrial, and trophoblast cell types in a timed and co-ordinated manner. In addition to the regulation of leukocyte migration and function, uterine chemokines also display specific roles in endometrial angiogenesis, apoptosis, proliferation, and differentiation. IL-8, MCP-1 and RANTES are regulated by local growth factors and cytokines such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma, and IL-1. IL-8 takes part in cervical ripening and parturition. IL-8, MCP-1 and RANTES are also found at high levels in the peritoneal fluid of women with endometriosis.

CONCLUSION

Co-ordination of chemokine-chemokine receptor interactions plays an important role in the menstrual cycle and successful pregnancy. Moreover, unbalanced chemokine expression contributes to pathologic conditions typified by uncontrolled cellular proliferation, migration and invasion.

Significance of fetal fibronectin and cytokine measurement in the cervicovaginal secretions of women at term in predicting term labor and post-term pregnancy

OBJECTIVE

To determine whether fetal fibronectin (FFN) or cytokine concentrations in cervicovaginal secretions can be used to predict term labor and post-term pregnancy.

STUDY DESIGN

FFN and cytokines were assayed in cervicovaginal mucus from 122 pregnant women at 29-35 weeks and weekly from week 36 to parturition.

RESULTS

FFN concentrations were elevated from about 3 weeks before parturition; a correlation was found between FFN levels and sampling-to-delivery intervals. Parturition was best predicted within 7 days of sampling when the FFN value was >or=50ng/ml between 36 and 41 gestational weeks. Interleukin-1beta (IL-1beta) concentrations were elevated from 3 to 4 weeks before parturition; a correlation was found between IL-1beta levels and sampling-to-delivery intervals. Parturition was best predicted within 7 days of sampling, with an IL-1beta cut-off value of >or=100pg/ml.

CONCLUSION

Term labor and post-term pregnancy can be predicted within 7 days of sampling, using FFN and IL-1beta concentrations in cervicovaginal secretions of pregnant women.