Progesterone represses interleukin-8 and cyclo-oxygenase-2 in human lower segment fibroblast cells and amnion epithelial cells

Progesterone receptor plays a major antiinflammatory role in human myometrial cells by antagonism of nuclear factor-kappaB activation of cyclooxygenase 2 expression

Spontaneous labor in women and in other mammals is likely mediated by a concerted series of biochemical events that negatively impact the ability of the progesterone receptor (PR) to regulate target genes that maintain myometrial quiescence. In the present study, we tested the hypothesis that progesterone/PR inhibits uterine contractility by blocking nuclear factor kappaB (NF-kappaB) activation and induction of cyclooxygenase-2 (COX-2), a contractile gene that is up-regulated in labor. To uncover mechanisms for regulation of uterine COX-2, immortalized human fundal myometrial cells were treated with IL-1beta +/- progesterone. IL-1beta alone caused a marked up-regulation of COX-2 mRNA, whereas treatment with progesterone suppressed this induction. This was also observed in human breast cancer (T47D) cells. In both cell lines, this inhibitory effect of progesterone was blocked by RU486. Using chromatin immunoprecipitation, we observed that IL-1beta stimulated recruitment of NF-kappaB p65 to both proximal and distal NF-kappaB elements of the COX-2 promoter; these effects were diminished by coincubation with progesterone. The ability of progesterone to inhibit COX-2 expression in myometrial cells was associated with rapid induction of mRNA and protein levels of inhibitor of kappaBalpha, a protein that blocks NF-kappaB transactivation. Furthermore, small interfering RNA-mediated ablation of both PR-A and PR-B isoforms in T47D cells greatly enhanced NF-kappaB activation and COX-2 expression. These effects were observed in the absence of exogenous progesterone, suggesting a ligand-independent action of PR. Based on these findings, we propose that PR may inhibit NF-kappaB activation of COX-2 gene expression and uterine contractility via ligand-dependent and ligand-independent mechanisms.

Dihydrotestosterone decreases tumor necrosis factor-alpha and lipopolysaccharide-induced inflammatory response in human endothelial cells

CONTEXT

An increasing body of evidence suggests that testosterone may exert beneficial effects on the development of atherosclerosis. It was suggested that testosterone may act after conversion into estradiol and activation of the estrogen receptors; however, a direct role of androgens on the vascular wall has been proposed.

OBJECTIVE

We investigated the effects of dihydrotestosterone on the proinflammatory response observed in human endothelial cells.

DESIGN

Human endothelial cells isolated from umbilical cords were incubated with lipopolysaccharide or TNFalpha in the presence or absence of dihydrotestosterone (DHT). mRNA and cellular proteins were processed for gene expression studies, and transient transfection experiments were performed to investigate molecular mechanisms involved in the effects observed.

SETTING

These studies took place at the Department of Pharmacological Sciences, University of Milan, Milan, Italy.

RESULTS

Lipopolysaccharide and TNFalpha induced VCAM-1 and ICAM-1 mRNA and protein expression, as detected by real-time quantitative PCR, fluorescence-activated cell sorting, and confocal microscopy, but this effect was inhibited when cells were incubated with DHT. In addition, DHT inhibited mRNA expression of IL-6, MCP-1, CD40, TLR4, PAI-1, and Cox-2 and the release of cytokines and chemokines such as GRO, granulocyte-macrophage colony-stimulating factor, and TNF. The DHT effect was counteracted by bicalutamide, an antagonist of the androgen receptor. Furthermore, when cells were cotransfected with a Cox-2 promoter or a 3X-NF-kappaB luciferase reporter vector and a plasmid expressing the human androgen receptor, DHT treatment inhibited the increase of the luciferase activity observed with TNFalpha.

CONCLUSION

DHT could positively regulate endothelial function through the control of the inflammatory response mediated by nuclear factor-kappaB in endothelial cells.

The role of nuclear factor kappa B in human labour

Preterm birth remains the leading cause of perinatal mortality and morbidity, largely as a result of a poor understanding of the precise mechanisms controlling labour onset in humans. Inflammation has long been recognised as a key feature of both preterm and term labour, with an influx of inflammatory cells into the uterus and elevated levels of pro-inflammatory cytokines observed during parturition. Nuclear factor kappa B (NF-κB) is a transcription factor family classically associated with inflammation. Accumulating evidence points to a role for NF-κB in the physiology and pathophysiology of labour. NF-κB activity increases with labour onset and is central to multiple prolabour pathways. Premature or aberrant activation of NF-κB may thus contribute to preterm labour. The current understanding of NF-κB in the context of human labour is discussed here.

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.

Gene regulation profile reveals consistent anticancer properties of progesterone in hormone-independent breast cancer cells transfected with progesterone receptor

Absence of estrogen receptor (ER) and progesterone receptor (PR) is the hallmark of most hormone-independent breast cancers. Previous studies demonstrated that reactivation of PR expression in hormone-independent MDA-MB-231 breast cancer cells enabled progesterone to suppress cell growth both in vitro and in vivo. We determined the whole genomic effect of progesterone in PR-transfected MDA-MB-231 cells. We identified 151 progesterone-regulated genes with expression changes > 3-fold after 24 hr treatment. Most are novel progesterone target genes. Real-time RT-PCR analysis of 55 genes showed a 100% confirmation rate. Twenty-six genes were regulated at both 3 and 24 hr. Studies using translation inhibitor suggest that most of the 26 genes are primary progesterone target genes. Progesterone consistently suppressed the expression of genes required for cell proliferation and metastasis and increased the expression of many tumor-suppressor genes. Progesterone also consistently decreased the expression of DNA repair and chromosome maintenance genes, which may be part of the mechanism leading to cell cycle arrest. These data suggest potential usefulness of progestin in combating ER-negative but PR-positive breast cancer and indicate that progesterone can exert a strong anticancer effect in hormone-independent breast cancer following PR reactivation. The identification of many novel progesterone target genes open up new avenues for in-depth elucidation of progesterone-mediated molecular networks.

Molecular and biochemical mechanisms of preterm labour

Parturition involves the synchronization of myometrial activity and structural changes of the cervix, leading to regular co-ordinated uterine contractions and cervical dilatation and effacement. The biochemical events involved in parturition resemble an inflammatory reaction, with growing evidence pointing to a crucial role for pro-inflammatory cytokines and prostaglandins in labour. There is accumulating evidence that there are common mediators involved in the regulation of 'labour-associated proteins', and that, in each case, an increase or decrease in gene expression mediates changes in their concentration. It is possible, therefore, that targeting these common mediators may represent newer strategies for the prevention of preterm labour. Our aim is to review the mechanical and biochemical mechanisms that may be involved in the processes of term and preterm labour. Specifically, we will consider the regulation of some of the 'labour-associated proteins', chemotactic cytokines, prostaglandins and enzymes of the prostaglandin biosynthetic pathway and the oxytocin receptor.

Factors involved in the inflammatory events of cervical ripening in humans

BACKGROUND

Cervical ripening is an inflammatory reaction. The glucocorticoid receptor (GR) mediates glucocorticoid anti-inflammatory reactions, whereas nuclear factor (NF)kappaB is a key pro-inflammatory transcription factor. Prostaglandins as well as platelet activating factor (PAF) are inflammatory mediators. Inducible nitric oxide synthase (iNOS) regulates the level of nitric oxide (NO) in response to various inflammatory stimuli. We hypothesize that a changed biological response to glucocorticoids could be a mechanism regulating the inflammatory events resulting in cervical ripening.

METHODS

We monitored GR and NFkappaB, prostaglandin synthases cyclooxygenase (COX)-1 and -2, iNOS, as well as the PAF-receptor (PAF-R) in the uterine cervix from term pregnant women (with unripe cervices) before the onset of labor (TP), immediately after parturition (PP), as compared to non-pregnant (NP), using immunohistochemistry and RT-PCR.

RESULTS

The GR protein was detected by immunohistochemistry in the nuclei of stroma and squamous epithelium (SQ). Stromal GR staining was increased in TP as compared to the NP group and decreased again after parturition. GR staining in SQ was decreased after parturition as compared to term. NFkappaB was present in SQ and glandular epithelium (GE), stroma and vascular endothelium. Increased nuclear NFkappaB staining was observed postpartum as compared to term pregnancy in stroma and GE. Stromal immunostaining for COX-1 as well as COX-2 was increased in the TP and PP groups as compared to the NP, and GE displayed an intensely increased COX-2 immunostaining at term and postpartum. Stromal PAF-R immunostaining was highest at term, while it was greatly increased in GE postpartum. No difference in the immunostaining for iNOS was found between the groups. RT-PCR showed a predominance of GRalpha to GRbeta mRNA in cervical tissue. The COX-2 mRNA level was increased in the PP group as compared to the TP group.

CONCLUSIONS

There is a decrease in GR levels in human cervix at parturition. Concomitantly there is an increase of factors such as NFkappaB, PAF-R, COX-1 and COX-2, suggesting that they may participate in the sequence of events leading to the final cervical ripening.

Mechanical stretch of human uterine smooth muscle cells increases IL-8 mRNA expression and peptide synthesis

Labour is associated with increased synthesis of interleukin-8 (IL-8) by the fetal membranes and myometrium, which leads to an inflammatory infiltrate. Stretch has been shown to increase the expression of contraction-associated proteins in animal models of labour and in human myocytes in vitro. In this study, we tested the hypothesis that mechanical stretch of human myometrial cells increases IL-8 messenger ribonucleic acid (mRNA) expression. We isolated myocytes from non-pregnant women undergoing hysterectomy and pregnant women undergoing Caesarean section before and after the onset of labour. Myocytes in culture were subjected to stretch of varying intensity (6-16%) and duration (1 or 6 h) using the Flexercell system. IL-8 mRNA expression was lowest in myocytes from pregnant women not in labour, intermediate in those from non-pregnant women and greatest in those from pregnant women in labour. Stretch increased IL-8 mRNA expression independent of reproductive state. The stretch-induced increase in IL-8 mRNA expression was associated with higher IL-8 levels in the culture supernatant and enhanced promoter activity. These data suggest that stretch contributes to the increase in myometrial IL-8 synthesis associated with the onset of labour in humans.

Steroidal regulation of uterine immune defenses

Progesterone suppresses uterine immune defenses and predisposes postpartum animals to nonspecific uterine infections. Progesterone can also suppress uterine eicosanoid synthesis. This effect of progesterone seems to be an important factor in the onset of uterine infections because eicosanoids can enhance uterine immune defenses. In fact, exogenous prostaglandin F(2alpha) (PGF(2alpha)), an eicosanoid that stimulates uterine PGF(2alpha) production, enhances uterine immune defenses and promotes the ability of ewes and sows to resolve uterine infections, even when progesterone is maintained at luteal phase concentrations. Prostaglandin F(2alpha) is also a proinflammatory molecule that stimulates the production of proinflammatory cytokines and may enhance uterine production of leukotriene B(4) (LTB(4)), which stimulates various neutrophil functions. Neutrophils seem to mount the initial response to bacteria that enter the uterus, and proinflammatory cytokines and LTB(4) enhance phagocytic activity of neutrophils. Even though there are clear associations among PGF(2alpha), LTB(4), proinflammatory cytokines, phagocytosis, and the ability of the uterus to resist or resolve infections, the mechanisms of action of exogenous PGF(2alpha) in mitigating the immunosuppressive effects of progesterone have not yet been defined. However, defining the PGF(2alpha) mechanisms should yield important new information that can be used to develop novel prevention and treatment strategies that do not rely on antibiotic and antimicrobial compounds for managing uterine infections.

Biosynthesis and catabolism of prostaglandin F2alpha (PGF2alpha) are controlled by progesterone in the rat uterus during pregnancy

Myometrial quiescence is a key factor in all species to accomplish a successful gestation. PGs play a crucial role in mediating parturition events, and their synthesis and metabolism are regulated by cyclooxygenases (COXs) and NAD(+)-dependent 15-hydroxy-PG dehydrogenase (PGDH), respectively. Progesterone (P(4)) is the hormone responsible for maintaining uterine smooth muscle quiescence during pregnancy. In this work, we have studied the effect of P(4) on the activity of COXs and PGDH, the uterine enzymes involved in the biosynthesis and metabolism of prostanoids in the rat. We found that during pregnancy PGF(2alpha) production and also protein levels of COX-1 and COX-2 were decreased. The exogenous administration of P(4) significantly inhibited the uterine production of PGF(2alpha) and also the protein level of COX-2. PGF(2alpha), metabolism was assessed by PGDH activity, which resulted high during pregnancy and increased as a result of P(4) administration. These results indicate that PGs levels were negatively modulated by P(4), which could be exerting its effect by increasing PGs metabolism through stimulation on PGDH activity and an inhibition on COX and that is a major mechanism for maintain uterine quiescence in pregnancy.

HDL 3 Induces Cyclooxygenase-2 Expression and Prostacyclin Release in Human Endothelial Cells Via a p38 MAPK/CRE-Dependent Pathway: Effects on COX-2/PGI-Synthase Coupling

Objective— In endothelial cells, cyclooxygenase-1 (COX-1) and COX-2 both contribute to prostacyclin production. Recent findings suggest that COX-2 contributes significantly to systemic prostacyclin synthesis in humans; whether COX-2 inhibition is related to an increased cardiovascular risk is undergoing debate. HDLs have been shown to increase prostacyclin synthesis, thus in the present study we investigated the molecular mechanisms involved in this effect in endothelial cells.

Methods and Results— HDL 3 (30 μg/mL) induced COX-2 expression in a time- and dose-dependent manner. COX-2 was found mainly in the perinuclear area where it co-localizes with PGI synthase. Transient transfection experiments showed that CRE is required for HDL-induced COX-2 transcription, and we demonstrated that p38 MAPK activation by HDL 3 is involved in COX-2 mRNA transcription and stabilization. As a consequence of COX-2-induction by HDL 3 prostacyclin production increased, incubation with a COX-2 selective inhibitor blocked this effect. Moreover, HDL 3 increased caveolin-1 phosphorylation, thus promoting PGI-synthase shuttling from the membrane to the perinuclear area.

Conclusion— We conclude that in endothelial cells, HDL modulates COX-2/PGI-S activity via both p38 MAPK-dependent COX-2 mRNA stability and transcription and both caveolin-1–dependent PGI-synthase shuttling and COX-2 coupling. The understanding of these mechanisms may provide new insights into the antiatherogenic role of HDL.

Components of diesel exhaust particles differentially affect lung expression of cyclooxygenase-2 related to bacterial endotoxin

We have reported previously that components of diesel exhaust particles (DEP) differently affect acute lung injury related to lipopolysaccharide (LPS) in mice. This study examined the effects of components of DEP on the lung expression of cyclooxygenase (COX)-1 and -2 in the presence or absence of LPS. ICR mice were divided into six experimental groups that received vehicle, LPS (2.5 mg kg(-1)), organic chemicals in DEP (DEP-OC) extracted with dichloromethane (4 mg kg(-1)), residual carbonaceous nuclei after the extraction (washed DEP: 4 mg kg(-1)), DEP-OC (4 mg kg(-1)) + LPS (2.5 mg kg(-1)) or washed DEP (4 mg kg(-1)) + LPS (2.5 mg kg(-1)) intratracheally. The expression of mRNA for both COXs in the lung was evaluated 4 h after the intratracheal administration. The magnitude of COX-1 mRNA expression was not altered in each group. The LPS treatment enhanced the COX-2 gene expression compared with vehicle treatment. Washed DEP combined with LPS further increased its expression compared with LPS alone. In contrast, combined treatment of DEP-OC with LPS decreased COX-2 gene expression compared with LPS alone. These results suggest that the residual carbonaceous nuclei of DEP predominantly enhance lung expression of COX-2 rather than the extracted organic chemicals from DEP in the presence of LPS, which is concomitant with the magnitude of acute lung injury in our previous study.

Steroidal regulation of uterine resistance to bacterial infection in livestock

Postpartum uterine infections reduce reproductive efficiency and have significant animal welfare and economic consequences. Postpartum uterine infections are classified as nonspecific, but Arcanobacterium pyogenes and Escherichia coli are usually associated with them in cattle and sheep. Pyometra is the most common type of uterine infection in dairy cattle, and it is detected almost exclusively in cows with active corpora lutea. Luteal progesterone typically down-regulates uterine immune functions and prevents the uterus from resisting infections. Progesterone also can down-regulate uterine eicosanoid synthesis. This seems to be a critical event in the onset of uterine infections, because eicosanoids can up-regulate immune cell functions in vitro. In addition, exogenous prostaglandin F2 alpha stimulates uterine secretion of prostaglandin F2 alpha and enhances immune functions in vivo. Thus, one may hypothesize that eicosanoids can override the negative effects of progesterone and that the up-regulatory effects of exogenous prostaglandin F2 alpha allow the uterus to resolve an infection, regardless of progesterone concentrations. Based on the results of studies to test that hypothesis, cows, sheep, and pigs in various physiological statuses are resistant to intrauterine infusions of Arcanobacterium pyogenes and Escherichia coli, unless progesterone concentrations are increased. In sheep and pigs, exogenous prostaglandin F2 alpha stimulates uterine production of prostaglandin F2 alpha and allows the uterus to resolve Arcanobacterium pyogenes-Escherichia coli-induced infections, even when progesterone is maintained at luteal phase concentrations before and after treatment. Prostaglandin F2 alpha is a proinflammatory molecule that stimulates the production of various proinflammatory cytokines, and it may enhance uterine production of leukotriene B4. Proinflammatory cytokines and leukotriene B4 enhance phagocytosis and lymphocyte functions. Even though there are clear associations among prostaglandin F2 alpha, leukotriene B4, proinflammatory cytokines, phagocytosis, and lymphocyte functions, the mechanism of action of exogenous prostaglandin F2 alpha in overriding the down-regulatory effects of progesterone and resolving uterine infections has not been elucidated. Defining this mechanism should yield new prevention and treatment strategies for uterine infections that do not rely on antibiotic and antimicrobial compounds.