Molecular cloning of a human MafF homologue, which specifically binds to the oxytocin receptor gene in term myometrium

Advancing our understanding of genetic risk factors and potential personalized strategies for pelvic organ prolapse

Pelvic organ prolapse is a common gynecological condition with limited understanding of its genetic background. In this work, we perform a genome-wide association meta-analysis comprising 28,086 cases and 546,291 controls from European ancestry. We identify 19 novel genome-wide significant loci, highlighting connective tissue, urogenital and cardiometabolic as likely affected systems. Here, we prioritize many genes of potential interest and assess shared genetic and phenotypic links. Additionally, we present the first polygenic risk score, which shows similar predictive ability (Harrell C-statistic (C-stat) 0.583, standard deviation (sd) = 0.007) as five established clinical risk factors combined (number of children, body mass index, ever smoked, constipation and asthma) (C-stat = 0.588, sd = 0.007) and demonstrates a substantial incremental value in combination with these (C-stat = 0.630, sd = 0.007). These findings improve our understanding of genetic factors underlying pelvic organ prolapse and provide a solid start evaluating polygenic risk scores as a potential tool to enhance individual risk prediction.

Although pelvic organ prolapse is a common gynecological condition, the genetic component of disease risk is not well known. Here the authors find common genetic variants associated with the disease and present a polygenic risk score to enhance individual risk prediction.

Possible kidney-lung cross-talk in COVID-19: in silico modeling of SARS-CoV-2 infection

Background

Publicly available genomics datasets have grown drastically during the past decades. Although most of these datasets were initially generated to answer a pre-defined scientific question, their repurposing can be useful when new challenges such as COVID-19 arise. While the establishment and use of experimental models of COVID-19 are in progress, the potential hypotheses for mechanisms of onset and progression of COVID-19 can be generated by using in silico analysis of known molecular changes during COVID-19 and targets for SARS-CoV-2 invasion.

Methods

Selecting condition: COVID-19 infection leads to pneumonia and mechanical ventilation (PMV) and associated with acute kidney injury (AKI). There is increasing data demonstrating mechanistic links between AKI and lung injury caused by mechanical ventilation.

Selecting targets: SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) for cell entry. We hypothesized that expression of ACE2 and TMPRSS2 would be affected in models of AKI and PMV. We therefore evaluated expression of ACE2 and TMPRSS2 as well as other novel molecular players of AKI and AKI-lung cross-talk in the publicly available microarray datasets GSE6730 and GSE60088, which represent gene expression of lungs and kidneys in mouse models of AKI and PMV, respectively.

Results

Expression of COVID-19 related genes ACE2 and TMPRSS2 was downregulated in lungs after 6 h of distant AKI effects. The expression of ACE2 decreased further after 36 h, while expression of TMPRSS2 recovered. In kidneys, both genes were downregulated by AKI, but not by distant lung injury. We also identified 53 kidney genes upregulated by PMV; and 254 lung genes upregulated by AKI, 9 genes of which were common to both organs. 3 of 9 genes were previously linked to kidney-lung cross-talk: Lcn2 (Fold Change (FC)_{Lung (L)} = 18.6, FC_{Kidney (K)} = 6.32), Socs3 (FC_L = 10.5, FC_K = 10.4), Inhbb (FC_L = 6.20, FC_K = 6.17). This finding validates the current approach and reveals 6 new candidates, including Maff (FC_L = 7.21, FC_K = 5.98).

Conclusions

Using our in silico approach, we identified changes in COVID-19 related genes ACE2 and TMPRSS2 in traditional mouse models of AKI and kidney-lung cross-talk. We also found changes in new candidate genes, which could be involved in the combined kidney-lung injury during COVID-19.

Polymorphism of the Oxytocin Receptor (OXTR) Gene Affects the Circulating Oxytocin Receptor Levels in Late-Term Pregnancy in a Turkish Population

INTRODUCTION

Postterm and late-term pregnancies still remain a serious health problem, and underlying exact mechanisms are not fully elucidated. These mechanisms are influenced by many factors.

OBJECTIVE

The aim of this study was to investigate the relationship between plasma oxytocin and oxytocin receptor levels and oxytocin receptor polymorphisms in term and late-term pregnant women.

METHODS

Sixty-eight singleton pregnant women with late-term pregnancy and 83 singleton pregnant women with term parturition were included in this study. A comparison was performed between pregnancies and neonates born at term (37 0/7 and 41 6/7 weeks' gestation). Plasma oxytocin, oxytocin receptor, estradiol, and progesterone levels were measured by using enzyme-linked immunosorbent assay kits. TaqMan® SNP Genotyping Assays and qPCR ProbesMaster were used to investigate the polymorphisms of rs237911, rs2228485, rs53576, and rs2254298.

RESULTS

There was not any difference in gene distributions of 4 common single-nucleotide polymorphisms of oxytocin receptor of rs237911, rs2228485, rs53576, and rs2254298 between subjects in late-term and term pregnancy groups. With rs53576 of the GG genotype, serum oxytocin levels were 21.50 ± 10.69 (ng/L) in the late-term group and 62.71 ± 18.01 (ng/L) in the term group (p = 0.049). Oxytocin receptor levels in the late-term and term pregnancy groups of the GG genotype were 17.92 ± 8.15 (pg/mL) and 45.77 ± 11.66 (pg/mL), respectively (p = 0.046).

CONCLUSION

Our findings suggest that the rs53576 oxytocin receptor single-nucleotide polymorphism is associated with late-term pregnancy through acting by direct modulation of oxytocin and oxytocin receptor levels.

RBFOX1 Regulates the Permeability of the Blood-Tumor Barrier via the LINC00673/MAFF Pathway

The blood-tumor barrier limits the delivery of therapeutic drugs to brain tumor tissues. Selectively opening the blood-tumor barrier is considered crucial for effective chemotherapy of glioma. RNA-binding proteins have emerged as crucial regulators in various biologic processes. This study found that RNA-binding Fox-1 homolog 1 (RBFOX1) was downregulated in glioma vascular endothelial cells derived from glioma tissues, and in glioma endothelial cells obtained by co-culturing endothelial cells with glioma cells. Overexpression of RBFOX1 impaired the integrity of the blood-tumor barrier and increased its permeability. Additionally, RBFOX1 overexpression decreased the expression of tight junction proteins ZO-1, occludin, and claudin-5. Subsequent analysis of the mechanism indicated that the overexpression of RBFOX1 increased musculoaponeurotic fibrosarcoma protein basic leucine zipper [bZIP] transcription factor F (MAFF) expression by downregulating LINC00673, which stabilized MAFF messenger RNA (mRNA) through Staufen1-mediated mRNA decay. Moreover, MAFF could bind to the promoter region and inhibit the promoter activities of ZO-1, occludin, and claudin-5, which reduced its expression. The combination of RBFOX1 upregulation and LINC00673 downregulation promoted doxorubicin delivery across the blood-tumor barrier, resulting in apoptosis of glioma cells. In conclusion, this study indicated that overexpression of RBFOX1 increased blood-tumor barrier permeability through the LINC00673/MAFF pathway, which might provide a new useful target for future enhancement of blood-tumor barrier permeability.

The earlier the gestational age, the greater the intensity of the intra-amniotic inflammatory response in women with preterm premature rupture of membranes and amniotic fluid infection by Ureaplasma species

Objectives To determine the relationship between the intensity of the intra-amniotic inflammatory response and the gestational age at the time of diagnosis in cases with preterm premature rupture of membranes (PROM) and intra-amniotic infection caused by Ureaplasma spp. Methods A retrospective cohort study was conducted which included 71 women with preterm PROM and a positive amniotic fluid culture with Ureaplasma spp. Women with mixed intra-amniotic infections were excluded. The study population was classified into three groups according to gestational age: group 1, <26 weeks (extreme preterm PROM, n = 17); group 2, 26.0-33.9 weeks (moderate preterm PROM, n = 39); group 3, 34.0-36.9 weeks (late preterm PROM, n = 15). The intensity of the intra-amniotic and maternal inflammatory response was compared among the three groups. The intensity of the intra-amniotic inflammatory response was assessed by the concentration of amniotic fluid matrix metalloproteinase-8 (MMP-8) and white blood cell (WBC) count. The maternal inflammatory response was assessed by the concentration of C-reactive protein (CRP) and WBC count in maternal blood at the time of amniocentesis. Results (1) The median values of amniotic fluid MMP-8 concentration and WBC count were the highest in the extreme preterm PROM group and the lowest in the late preterm PROM group (P < 0.001 and P = 0.01, respectively); (2) the intensity of the maternal inflammatory response measured by maternal blood WBC count and CRP concentration was not significantly associated with gestational age at the time of diagnosis. Conclusion The earlier the gestational age at the time of PROM, the higher the intensity of the intra-amniotic inflammatory response in women with preterm PROM and intra-amniotic infection caused by Ureaplasma spp.

Regulation of CXCL1 chemokine and CSF3 cytokine levels in myometrial cells by the MAFF transcription factor

Cytokines play key roles in a variety of reproductive processes including normal parturition as well as preterm birth. Our previous data have shown that MAFF, a member of the MAF family of bZIP transcription factors, is rapidly induced by pro‐inflammatory cytokines in PHM1‐31 myometrial cells. We performed loss‐of‐function studies in PHM1‐31 cells to identify MAFF dependent genes. We showed that knockdown of MAFF significantly decreased CXCL1 chemokine and CSF3 cytokine transcript and protein levels. Using chromatin immunoprecipitation analyzes, we confirmed CXCL1 and CSF3 genes as direct MAFF targets. We also demonstrated that MAFF function in PHM1‐31 myometrial cells is able to control cytokine and matrix metalloproteinase gene expression in THP‐1 monocytic cells in a paracrine fashion. Our studies provide valuable insights into the MAFF dependent transcriptional network governing myometrial cell function. The data suggest a role of MAFF in parturition and/or infection‐induced preterm labour through modulation of inflammatory processes in the microenvironment.

Evolutionary Rewiring of Human Regulatory Networks by Waves of Genome Expansion

Genome expansion is believed to be an important driver of the evolution of gene regulation. To investigate the role of a newly arising sequence in rewiring regulatory networks, we estimated the age of each region of the human genome by applying maximum parsimony to genome-wide alignments with 100 vertebrates. We then studied the age distribution of several types of functional regions, with a focus on regulatory elements. The age distribution of regulatory elements reveals the extensive use of newly formed genomic sequence in the evolution of regulatory interactions. Many transcription factors have expanded their repertoire of targets through waves of genomic expansions that can be traced to specific evolutionary times. Repeated elements contributed a major part of such expansion: many classes of such elements are enriched in binding sites of one or a few specific transcription factors, whose binding sites are localized in specific portions of the element and characterized by distinctive motif words. These features suggest that the binding sites were available as soon as the new sequence entered the genome, rather than being created later by accumulation of point mutations. By comparing the age of regulatory regions to the evolutionary shift in expression of nearby genes, we show that rewiring through genome expansion played an important role in shaping human regulatory networks.

Mutant p53 gains new function in promoting inflammatory signals by repression of the secreted interleukin-1 receptor antagonist

The TP53 tumor-suppressor gene is frequently mutated in human cancer. Missense mutations can add novel functions (gain-of-function, GOF) that promote tumor malignancy. Here we report that mutant (mut) p53 promotes tumor malignancy by suppressing the expression of a natural occurring anti-inflammatory cytokine, the secreted interleukin-1 receptor antagonist (sIL-1Ra, IL1RN). We show that mutp53 but not wild-type (wt) p53 suppresses the sIL-1Ra production in conditioned media of cancer cells. Moreover, mutp53, but not wtp53, binds physically the sIL-1Ra promoter and the protein-protein interaction with the transcriptional co-repressor MAFF (v-MAF musculoaponeurotic fibrosarcoma oncogene family, protein F) is required for mutp53-induced sIL-1Ra suppression. Remarkably, when exposed to IL-1 beta (IL-1β) inflammatory stimuli, mutp53 sustains a ready-to-be-activated in vitro and in vivo cancer cells' response through the sIL-1Ra repression. Taken together, these results identify sIL-1Ra as a novel mutp53 target gene, whose suppression might be required to generate a chronic pro-inflammatory tumor microenvironment through which mutp53 promotes tumor malignancy.

Small Maf proteins in mammalian gene control: mere dimerization partners or dynamic transcriptional regulators?

The small Maf basic leucine zipper (bZIP) proteins MafF, MafG and MafK, while modest in size, have emerged as crucial regulators of mammalian gene expression. Intriguingly, small Mafs do not contain an obvious transcriptional activation domain. However, previously perceived as "mere" partner molecules conferring DNA binding specificity to complexes with larger bZIP proteins, such as the CNC family member Nrf2, it has become clear that small Maf proteins are essential and dynamically regulated transcription factors. Current data suggest stringent control of small Maf protein function through transcriptional and post-translational mechanisms. Initial gene targeting experiments revealed considerable functional redundancy among small Maf proteins in vivo. This was not unexpected, due to the high level of homology among the three small Mafs. Nevertheless, further studies showed that these transcription factors have critical roles in various cellular processes, including stress signaling, hematopoiesis, CNS function and oncogenesis. Recent data provide a possible link between small Maf-mediated transcription and the inflammatory response.

Identification of interleukin-1β regulated genes in uterine smooth muscle cells

We analyzed the response of uterine smooth muscle cells to interleukin-1β (IL-1β). We first showed that PHM1-31 myometrial cells, our cellular model, are contractile. To determine the molecular mechanisms of uterine smooth muscle cell activation by proinflammatory cytokines, we performed genechip expression array profiling studies of PHM1-31 cells in the absence and the presence of IL-1β. In total, we identified 198 known genes whose mRNA levels are significantly modulated (> 2.0-fold change) following IL-1β exposure. We confirmed the expression changes for selected genes by independent mRNA and protein analysis. The group of genes induced by IL-1β includes transcription factors and inflammatory response genes such as nuclear factor of κ light polypeptide gene enhancer in B-cells (NFκB), pentraxin-related gene (PTX3), and tumor necrosis factor α-induced protein 3/A20 (TNFAIP3/A20). We also found up-regulation of chemokines like C-X-C motif ligand 3 (CXCL3) and extracellular matrix remodeling signaling molecules like tenascin C (TNC). Our data suggest that IL-1β elicits the rapid activation of a cellular network of genes particularly implicated in inflammatory response that may create a cellular environment favorable for myometrial cell contraction. Our results provide novel insights into the mechanisms of uterine smooth muscle cell regulation and possibly infection-induced preterm labor.

The novel human gene MIP functions as a co-activator of hMafF

The human transcription factor MafF (hMafF) lacks a transactivation domain, it contains a heptad-leucine repeat motif (viz., Leu-zipper) that may mediate protein-protein interactions to regulate transcriptional activities. A protein with a coiled-coil domain encoded by a novel human gene (GenBank Accession No. AF289559) was found to interact with hMafF in vitro and in vivo and is designated as a MafF interacting protein (MIP). Here, we provide evidence that the coiled-coil domain of MIP is essential for binding to the Leu-zipper of hMafF and that the interaction between MIP and hMafF causes the translocalization of MIP from cytoplasm to nucleolus in HELA cells. We used a promoter-reporter system containing six tandem repeats of the US2 element, located in the promoter of the human oxytocin receptor gene and reported to bind specifically to hMafF, to understand effects on transcriptional activation of hMafF, and its interaction with MIP. Expression of hMafF or MIP alone did not alter basal reporter transcription activity, whereas co-expression of hMafF and MIP activated transcription efficiently. Moreover, truncated MIP, still containing the coiled-coil domain, transactivated as well as the full-length MIP did, and highlighting that MIP acts as a co-activator of hMafF.

Chase M, Johannsen E, Kieff E, Cahir-McFarland E. RNAs induced by Epstein-Barr virus nuclear antigen 2 in lymphoblastoid cell lines

Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2) association with RBP-Jkappa is essential for regulation of virus and cell gene transcription and B lymphocyte transformation into infinitely proliferating lymphoblastoid cells (LCLs). To identify EBNA2-regulated cell genes in LCLs, an EBV recombinant that expresses EBNA2 with its C terminus fused in frame to a 4-hydroxytamoxifen (4HT)-dependent mutant estrogen receptor (E2HTF) was used to transform primary B lymphocytes to LCLs. In the presence of 4HT, E2HTF expression level and effects on the LMP1 promoter in transfected BJAB lymphoblasts were similar to EBNA2. In 4HT-supplemented medium, E2HTF EBV recombinant infected LCLs were also similar to EBNA2 LCLs in outgrowth but required higher serum and a restricted range of cell concentrations for consistent growth. In medium without 4HT, E2HTF localized to the cytoplasm, c-myc levels substantially decreased within 6 h, cells stopped growing, and levels of other EBNAs and LMP1 remained stable for 24 h. Over this 24-h period, 30 cell RNAs decreased 2-fold, and 51 other RNAs decreased 1.5-fold. These RNAs encode proteins important in cell adhesion or signaling, transcription, RNA processing, cell-cycle regulation, and survival. Real-time RT-PCR confirmed EBNA2-dependent expression of eight RNAs.

Regulation of the MAFF transcription factor by proinflammatory cytokines in myometrial cells

The MAF (proto-)oncogene family of basic-leucine zipper transcription factors plays crucial roles in the control of mammalian gene expression and development. Here we analyzed the regulation of the human MAFF gene, coding for a small MAF transcription factor, in uterine smooth muscle cells. We found that MAFF transcript levels are induced by proinflammatory cytokines in PHM1-31 myometrial cells. We observed an important induction by interleukin 1 beta (IL1B) and a weaker upregulation by tumor necrosis factor (TNF), whereas interleukin 6 (IL6) treatment had no effect. Time course experiments revealed a rapid induction of MAFF transcripts within 30 min following IL1B treatment. The presence of actinomycin D inhibited the upregulation, suggesting that regulation of MAFF mRNA levels occurs at the transcriptional level. We generated a MAFF-specific antiserum and determined that MAFF protein was also induced by TNF and IL1B in PHM1-31 cells. In contrast, it was particularly interesting that the transcript and protein levels of the highly homologous MAFG and MAFK genes are not modulated by these cytokines. Our results suggest a possible specific role for MAFF in proinflammatory cytokine-mediated control of myometrial gene expression and provide the first link between a small MAF transcription factor and the inflammatory response.

MafT, a new member of the small Maf protein family in zebrafish

Small Maf proteins play critical roles on morphogenesis and homeostasis through associating with CNC proteins. To date, three small Maf proteins, MafF, MafG, and MafK, have been reported in vertebrates, which share redundant functions. In this study, we tried to identify and characterize small Maf proteins in zebrafish to elucidate their conservation and diversity in the fish kingdom. We identified homolog genes of MafG and MafK but not MafF in zebrafish, indicating the former two are conserved among vertebrates. In addition, a novel type of small Maf protein MafT was identified. MafT protein bound MARE sequence as a homodimer or heterodimers with zebrafish Nrf2 or p45 Nfe2. Co-overexpression of MafT and Nrf2 synergistically activated MARE-mediated gene expression in zebrafish embryos. These results indicated that MafT is a new member of small Maf proteins and involved in the Nrf2-dependent gene regulation in cellular defense system.

Microarray analysis of uterine gene expression in mouse and human pregnancy

Improved care of infants born prematurely has increased their survival. However, the incidence of preterm labor has not changed. To understand the processes involved in preterm labor, we used oligonucleotide microarrays to study gene expression in murine and human uterus during pregnancy. The induction of enzymes for prostaglandin synthesis was used as a marker for important changes during pregnancy because prostaglandins strongly contribute to both human and murine labor. We identified 504 genes that changed at least 2-fold between d 13.5 and 19.0 in the gravid mouse uterus. In the pregnant human myometrium, we found 478 genes that changed at least 2-fold in either term or preterm labor compared with preterm nonlabor specimens and 77 genes that significantly varied in both preterm and term labor. Patterns of gene regulation within functional groups comparing human preterm and term labor were similar, although the magnitude of change often varied. Surprisingly, few genes that changed significantly throughout pregnancy were the same in the mouse and human. These data suggest that functional progesterone withdrawal in human myometrium may not be the primary mechanism for labor induction, may implicate similar mechanisms for idiopathic preterm and term labor in humans, and may identify novel targets for further study.

Regulation of oxytocin receptor expression in cultured human myometrial cells by fetal bovine serum and lysophospholipids

Oxytocin receptor (OTR) expression in human myometrium increases over 150-fold from the beginning of pregnancy to the end. In the present studies, we examined potential mechanisms of OTR up-regulation, using myometrial cells in primary culture from women in late gestation. OTR ligand-binding sites and steady-state mRNA levels were down regulated by serum starvation, and up-regulated by restoration of fetal bovine serum (FBS). Transcriptional activity of the OTR gene was the same with or without FBS treatment, but FBS increased OTR mRNA half-life about 5-fold. Lysophospholipids (lysophosphatidic acid and sphingosine 1-phosphate), which are present in serum, had similar effects as FBS. Lysophospholipid receptor mRNAs of the endothelial differentiation gene (Edg) family (Edgs 1, 3, 4, and 5) were demonstrated in myometrial cells by RT-PCR. These G protein-coupled receptors have been shown to be coupled to G(i/o) and to mediate activation of phosphoinositol 3-phosphate kinase. Indeed, the effects of the lysophospholipids and FBS were completely blocked by pertussis toxin, a G(i/o) inhibitor. Likewise, inhibition of G(i/o) signaling by elevation of intracellular cAMP or inhibition of phosphoinositol 3-phosphate kinase blocked FBS effects on OTR mRNA stability. We do not presently understand the mechanisms of OTR up-regulation in human myometrium in vivo, but the present studies might lead to the description of mRNA-stabilizing factors whose activity can be quantified in tissue samples during pregnancy to elucidate the process of OTR up-regulation.

Cloning MafF by recognition site screening with the NFE2 tandem repeat of HS2: analysis of its role in globin and GCSl genes regulation

The erythroid-specific enhancer within hypersensitivity site 2 (HS2) of the human beta-globin locus control region is required for high level globin gene expression. We used an oligonucleotide of the NF-E2 tandem repeat, within HS2, as recognition site probe to screen a K562 cDNA library for interacting transcription factors. A 2.3 kb full length cDNA encoding the b-zip transcription factor MafF was isolated. MafF can form both homodimers and high affinity heterodimers with Nrf1, Nrf2 and Nf-E2, three members of the CNC-bZip family. Despite obvious structural similarities with the other small Maf proteins, MafF differs in its tissue distribution and its inability to repress transcription when overexpressed as homodimer. In fact, in different cell lines and on different promoters (gamma-globin, beta-globin and glutamylcysteine synthetase genes) the MafF homodimers do not appreciably affect transcription of target promoters, whereas MafF/CNC member heterodimers act as weak transcriptional activators. Even though MafF was cloned using probes derived from the globin LCR, it is in the context of the GCSl promoter and in combination with Jun that MafF shows a rather distinct and specific regulatory role. These observations suggest that a complex network of small Maf and CNC-AP1 protein interactions might be involved in regulating transcription in diverse tissues or developmental stages.

DNA methylation of the human oxytocin receptor gene promoter regulates tissue-specific gene suppression

In the human oxytocin receptor (OTR) gene, there is a CpG island from 140 bp upstream to 2338 bp downstream of the transcription start site (TSS). We investigated whether the methylation state of this region affects the transcription of the OTR gene. HepG2 derived from human hepatoblastoma, in which OTR gene transcription was suppressed, was treated with a demethylating agent, 5-azacytidine (Aza-C) for 2 days. Semiquantitative RT-PCR indicated that OTR mRNA was significantly increased by Aza-C treatment in a dose-dependent manner. We estimated the level of methylation within the CpG islands of the OTR gene in peripheral blood leukocytes, nonpregnant uterine myometrium, term uterine myometrium and liver. A 1.5-kb region located 5' upstream of the translation start site was divided into four fragments. Each was amplified by PCR after complete digestion with methylation-sensitive restriction enzyme HpaII. The amount of PCR products was largest in the liver, suggesting that this CpG island in the OTR gene is most highly methylated in liver, where the gene is always inactivated. We compared the effect of in vivo methylation of the CpG island on transcriptional activity of an OTR-reporter plasmid. The reporter gene activity of expression plasmid -2860/+1342-GL3, containing the CpG island, in HepG2 cells was suppressed to 30.6% of the control level after methylation with SssI methylase, while that of -2840/+144-GL3, without the CpG island was suppressed only to 81.4%. The deletion of the segment (MT2) where the level of methylation was most different between liver and uterus (-2860/+1342(del)MT2-GL3) rescued the suppression rate to 68.0%. These results indicate that the methylation of the CpG island in the human OTR gene promoter suppressed its transcription at least in liver and may regulate tissue specific gene expression among organs.

Cytokine production in chorioamnionitis

Lymphohematopoietic cytokines play a significant role in many biological mechanisms including a number of reproductive processes such as ovulation, implantation, placentation, cervical dilation and parturition. Recent experiments have suggested that cytokines play a crucial role in the mechanisms of preterm labor and delivery, which are the leading causes of perinatal morbidity and mortality. Growing evidence suggests that infection is deeply concerned in the pathogenesis of preterm labor and delivery. Chorioamnionitis, a subset of intrauterine infection, has been identified in 20-33% of women with preterm delivery, and the inflammatory and related cytokines, interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8), showed substantial increases in the amniotic fluid at women with intrauterine infection. Although the precise mechanism for chorioamnionitis-driven preterm labor mediated via cytokines is still unknown, both IL-1 and TNF-alpha along with IL-6 enhance prostaglandin production by human amnion cells, chorionic cells and decidual cells. Analysis of the regulatory sequences in the 5' upstream regions of receptor gene for human oxytocin, a potent uterotonic agent, suggests a close relationship between preterm labor and inflammatory cytokines through induction at the oxytocin receptor. Prompt identification of the patients with intra-amniotic infection may be useful in clinical practice. At present, the measurement of IL-8 in maternal serum or the measurement of IL-6 in cervical secretion may be helpful as a non-invasive screening for chorioamnionitis.