Hemoxygenase and nitric oxide synthase do not maintain human uterine quiescence during pregnancy

Role of heme Oxygenase-1 in low dose Radioadaptive response

Radioadaptive response (RAR) is an important phenomenon induced by low dose radiation. However, the molecular mechanism of RAR is obscure. In this study, we focused on the possible role of heme oxygenase 1 (HO-1) in RAR. Consistent with previous studies, priming dose of X-ray radiation (1–10 cGy) induced significant RAR in normal human skin fibroblasts (AG 1522 cells). Transcription and translation of HO-1 was up-regulated more than two fold by a priming dose of radiation (5 cGy). Zinc protoporphyrin Ⅸ, a specific competitive inhibitor of HO-1, efficiently inhibited RAR whereas hemin, an inducer of HO-1, could mimic priming dose of X-rays to induce RAR. Knocking down of HO-1 by transfection of HO-1 siRNA significantly attenuated RAR. Furthermore, the expression of HO-1 gene was modulated by the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which translocated from cytoplasm to nucleus after priming dose radiation and enhance the antioxidant level of cells.

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The critical role of HO-1 in low dose Radioadaptive response is proposed.

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Low dose irradiation activates Nrf2 Translocation and HO-1 expression.

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Nrf2/HO-1 pathway mediates Radioadaptive response via regulating ROS production.

Expression of heme oxygenase-1 in the peripheral blood mononuclear cells from asthmatic patients

To explore the expression of heme oxygenase-1 (HO-1) in the peripheral blood mononuclear cells (PBMCs) and its relationship with pulmonary ventilation function in asthmatic patients, 18 asthmatic patients and 18 healthy subjects were selected. HO-1 protein and mRNA levels in PBMCs were measured by immunohistochemical staining and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Blood carbon monoxide Hb (COHb), serum total IgE and pulmonary ventilatory function were observed. Our results showed that the percentage of cells positive for immunohistochemical staining of HO-1 were significantly higher in asthmatic patients (41.72 +/- 7.44) % than that in with healthy subjects (10.45 +/- 4.36) % (P < 0.001) and the optical density of PBMC HO-1 mRNA was higher in asthmatic patients (26.05 +/- 4.14) than that in healthy subjects (10. 82 +/- 4.26) (P < 0.001). The relation analysis showed that PBMC HO-1 protein and mRNA levels had significantly negative relation with FEV1%, PEFR, MEFR50%, respectively (r = -0.51-0.89, P < 0.05-0.001, respectively) and a positive relation with COHb and serum total IgE (r = 0.48-0. 85, 0.05-0.001, respectively). It is concluded that the expression of PBMC HO-1 protein and mRNA increased significantly in asthmatic patients, and HO-1 may play a significant role in the pathogenesis of asthma. The expression of HO-1 may bear a relation with severity of asthma.

Heme oxygenase-carbon monoxide (HO-CO) system in rat uterus: effect of sexual steroids and prostaglandins

Pregnancy maintenance is a very complex phenomenon, and the mechanisms that allow the survival of the fetus within the maternal uterus are still poorly understood. Our objectives were to analyze heme oxygenase (HO) activity and expression in the pregnant rat and to study its association with steroid hormones and prostaglandins. Uterine tissues were obtained from non-pregnant and from time-mated rats at days 5, 13, 18-22 of pregnancy and postpartum. HO activity was significantly higher at days 5 and 20 while HO-1 protein levels measured by Western blot, were significantly elevated from days 19 to 22. In ovariectomized rats, estrogen and progesterone in estrogenized animals increased HO activity and expression. Cyclooxygenase inhibitors augmented HO activity and HO-1 expression. Pre-incubation with prostaglandin F2alpha (PGF2alpha) diminished the enzymatic activity in ovariectomized rat uterus. Tin protoporphyrin IX, an HO inhibitor, significantly decreased uterine cGMP accumulation. Bilirubin decreased uterine thiobarbituric acid substances levels (an index of lipid peroxidation). These results demonstrate a uterine gestational pattern of HO activity and expression in the rat. In addition, these results suggest that uterine HO activity could regulate uterine quiescence in pregnancy via cGMP and it may contribute to the defense against oxidative stress.

Carbon Monoxide: Endogenous Production, Physiological Functions, and Pharmacological Applications

Over the last decade, studies have unraveled many aspects of endogenous production and physiological functions of carbon monoxide (CO). The majority of endogenous CO is produced in a reaction catalyzed by the enzyme heme oxygenase (HO). Inducible HO (HO-1) and constitutive HO (HO-2) are mostly recognized for their roles in the oxidation of heme and production of CO and biliverdin, whereas the biological function of the third HO isoform, HO-3, is still unclear. The tissue type-specific distribution of these HO isoforms is largely linked to the specific biological actions of CO on different systems. CO functions as a signaling molecule in the neuronal system, involving the regulation of neurotransmitters and neuropeptide release, learning and memory, and odor response adaptation and many other neuronal activities. The vasorelaxant property and cardiac protection effect of CO have been documented. A plethora of studies have also shown the importance of the roles of CO in the immune, respiratory, reproductive, gastrointestinal, kidney, and liver systems. Our understanding of the cellular and molecular mechanisms that regulate the production and mediate the physiological actions of CO has greatly advanced. Many diseases, including neurodegenerations, hypertension, heart failure, and inflammation, have been linked to the abnormality in CO metabolism and function. Enhancement of endogenous CO production and direct delivery of exogenous CO have found their applications in many health research fields and clinical settings. Future studies will further clarify the gasotransmitter role of CO, provide insight into the pathogenic mechanisms of many CO abnormality-related diseases, and pave the way for innovative preventive and therapeutic strategies based on the physiologic effects of CO.

Increased expression and activity of heme oxygenase-2 in pregnant rat aorta is not involved in attenuated vasopressin-induced contraction

Pregnancy is associated with attenuated vascular reactivity to a variety of contractile agonists. Heme oxygenases are expressed in the placenta, and it has been suggested that the heme oxygenase/carbon monoxide (HO/CO) pathway plays a significant role in regulating blood flow through the feto-placental unit. In this study we investigated the possible involvement of heme oxygenases in the reduced vascular reactivity associated with pregnancy. Arginine vasopressin (AVP) (10(-10)-3x10(-7) M) induced concentration-dependent contraction of aortic ring segments from non-pregnant and pregnant (16-19 days) rats. Pregnancy did not alter the sensitivity to AVP (pD2=8.5+/-0.1 and pD2=8.4+/-0.2 in non-pregnant and pregnant rats, respectively) but significantly reduced the maximum response (107.9+/-12.7% and 38.6+/-7.4%, respectively, relative to noradrenaline-induced contraction). Western blot analysis revealed the expression of HO-2 but not HO-1 isoform in both groups. There was a significant increase in the expression and activity of HO-2 protein in aortic tissues from pregnant rats compared with those from age-matched non-pregnant rats. In the presence of L-NAME to inhibit nitric oxide (NO) synthesis, tin protoporphyrin IX (SnPP-IX, 10(-5) M), an inhibitor of heme oxygenase, did not significantly affect AVP-induced contraction in aorta segments from pregnant and non-pregnant rats. It was concluded that, though pregnancy increased the expression and activity of HO-2 in the aorta, HO-2 was not involved in the attenuated response to AVP.

Heme oxygenase as a therapeutic target in immunological pregnancy complications

The allogeneic fetus has been considered to be an allograft and the tolerance mechanisms involved in pregnancy maintenance resemble those leading to graft acceptance. Up-regulation of Heme Oxygenase-1 (HO-1) promotes graft acceptance. Additionally, HO-1 has been proposed to have tissue-protective properties. Previous studies reported the presence of HO-1 and HO-2 in mammalian placenta and postulated a protective role for HO during pregnancy. Here, we analyze HO-1 and HO-2 expression at the feto-maternal interface from normal pregnant and abortion mice and correlate these findings with inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expression as well as with Th1/Th2 cytokine production by immune cells. DBA/2-mated CBA/J females undergoing abortion and BALB/c-mated CBA/J females having normal pregnancies were included in our study. The mice received no treatment. On day 14 of pregnancy, the mice were sacrificed, the abortion rate was calculated and the ex vivo Th1/Th2 production by decidual immune cells was analyzed by flow cytometry. The expression of HO-1 and HO-2, iNOS and eNOS was analyzed by immunohistochemistry (IHC) and Western blot in placenta samples. The Th1/Th2 cytokines ratio was augmented in decidua from abortion mice. We further observed a significant down-regulation of HO-1, HO-2, iNOS and eNOS molecules in placental tissue from mice undergoing abortion when compared to normal pregnant mice. Since we found diminished HOs and nitric oxide synthase (NOS) levels at the feto-maternal interface from abortion mice when compared to normal pregnant mice, which were further associated with increased Th1/Th2 cytokine production, we propose HO as a putative therapeutic target in immunological abortions. Up-regulation of HO-1 or HO-2 would favour the Th2-cytokine production, which could avoid abortion onset.

In vitro responsiveness of human post-menopausal myometrium to endothelin-1 and ovarian steroids

It has been shown in vitro that endothelin 1 (ET1) differentially affects the human myometrial contractility according to the hormonal profile of women. Our purpose was to test the hypothesis that ovarian steroids influence the ET1 induced myometrial contractility. We performed three types of experiments. Myometrial tissues were exposed to 17beta-oestradiol (E), progesterone (P), E plus P (E+P) in concentrations 10(-10)M, 10(-8)M, 10(-7)M, 10(-6)M and 10(-4)M (Type I), ET1 in concentrations 10(-10)M, 10(-9)M, 10(-8)M, 10(-7)M and 10(-6)M (Type II) and E+ET1, P+ET1 and E+P+ET1 in concentrations ranging from 10(-10)M to 10(-6)M (Type III). Tissue exposure to E, P and E+P did not significantly alter the pattern of spontaneous myometrial motility. ET1 (10(-6)M) induced a sustained long-lasting contraction, the initial part of which lasted 34 +/- 4 min, elevating the initial baseline by 190 +/- 20%. This was followed by ripples of gradually increasing amplitude with no regular contractions up to the end of the period of observation (120 min). Addition of P or E+P to ET1 markedly restricted (p<0.05) the elevation of initial baseline (P+ET1: 68 +/- 8%, P+E+ET1: 67 +/- 8%), and significantly shortened (p<0.01) the duration of the alterations (P+ET1: 21 +/- 3 min, P+E+ET1: 26 +/- 3 min). These results demonstrate the lack of any significant effect of E and P or their combinations on the pattern of spontaneous myometrial motility in post-menopausal women. However, P alone or in combination with E exerted an inhibitory action on ET1 -induced contractility on human post-menopausal myometrium. The physiological significance of these findings remains to be clarified.

HO in pregnancy

The enzyme heme oxygenase (HO) has been implicated in several physiological functions throughout the body including control of vascular tone and regulation of the inflammatory and apoptotic cascades as well as contributing to the antioxidant capabilities in several organ systems. These various properties attributed to HO are carried out through the catalytic products of heme degradation, namely carbon monoxide (CO), biliverdin, and free iron (Fe2+). As the newly emerging roles of HO in normal organ function have come to light, researchers in several disciplines have assessed the role of this enzyme in various physiological and pathological changes taking place in the human body over a lifetime. Included in this new wave of interest is the involvement of HO, and its by-products, in the normal function of the vital organ of pregnancy, the placenta. In this review the role of HO, and its catalytic products, will be examined in the context of pregnancy. The different isoforms of the HO enzyme (HO-1, HO-2, HO-3) have been localized throughout placental tissue, and have been shown to be physiologically active. The HO protein and more specifically its catalytic by-products (CO, biliverdin, and Fe2+) have been postulated to be involved in the maintenance of uterine quiescence throughout gestation, regulation of hemodynamic control within the uterus and placenta, regulation of the apoptotic and inflammatory cascades in trophoblast cells, and the maintenance of a balance of the oxidant-antioxidant status within the placental tissues. The association between this enzyme system, and its above-noted roles throughout pregnancy, with the hypertensive disorder of pregnancy preeclampsia (PET), will also be examined. It is hypothesized that a decrease in HO expression and/or activity throughout gestation would be capable of initiating several pathological processes involved in the etiology of PET. This hypothesis has led to further discussion emphasizing the possibility of novel therapeutic designs targeting this enzyme system for the treatment of PET.

Heme oxygenase expression in cultured human trophoblast cells during in vitro differentiation: effects of hypoxia

Heme oxygenases (HO-1 and HO-2) are responsible for the production of carbon monoxide, a vasodilator. HO is important in controlling placental blood flow and expression can be sensitive to oxygen. We previously reported a reduction in HO-2 expression in placentae obtained from patients with pre-eclampsia or living at high altitude, both associated with placental hypoxia. Thus we hypothesized that HO expression in cultured trophoblasts would be altered by exposure to hypoxia. HO-1 and HO-2 expression was assessed in trophoblast cell cultures following exposure to different oxygen environments. Western blot analyses showed that HO-1 expression in syncytiotrophoblast was significantly lower than in cytotrophoblasts in standard conditions (p < 0.05). There was no difference in HO-1 expression in cytotrophoblasts transferred to 2% O2 for various times. However, exposure of syncytiotrophoblast cultures to hypoxia for 12 h resulted in a significant reduction in HO-1 expression (p < 0.05). HO-2 expression was not affected by exposure to hypoxia in either cytotrophoblast or syncytiotrophoblast cultures. Possible interpretations of these findings are that chronic hypoxia alone is not responsible for reduced HO-2 expression or a much longer exposure to chronic hypoxia (perhaps months) is required. This study also reinforces the complexities of HO regulation by oxygen.

End-tidal breath carbon monoxide measurements are lower in pregnant women with uterine contractions

OBJECTIVE

To compare the levels of end-tidal carbon monoxide (ETCOc) among women with and without uterine contractions in term and preterm pregnancies.

STUDY DESIGN

In all, 55 nonsmoking healthy pregnant women were enrolled. ETCOc levels were compared among women with contractions (10 preterm and 13 term) and 32 women without contractions (34-41 weeks gestation).

RESULTS

Maternal age, gravidity and parity were similar among study and control groups. ETCOc levels were significantly lower among women that had uterine contractions (0.99+/-0.38 parts per million (ppm) and 1.15+/-0.34 p.p.m. respectively), compared to women with no contractions (1.70+/-0.52 p.p.m., P<0.002). However, there was no significant difference in the ETCOc levels between women with preterm or term contractions (P=0.48).

CONCLUSIONS

Low levels of ETCOc are associated with preterm and term uterine contractions.

Prostaglandins and the myometrium and cervix

Prostaglandins have long been thought to play important roles in the mechanism of parturition. Here we review the involvement of prostaglandins in myometrial and cervical functions with emphasis on human labor and birth. In addition, the cellular sources of prostaglandins as well as their interactions with various other endocrine, paracrine and physical factors, such as oxytocin, corticotropin releasing hormone, nitric oxide, platelet activating factor, cytokines, endothelin and stretch are also addressed together with their potential role in the molecular reorganization of cervical structure associated with labor and delivery. Finally, the premier role of progesterone in pregnancy maintenance and parturition is juxtaposed with the proposed "fine-tuning", modulatory role of prostaglandins and the above listed factors in the regulation of parturition.

FGL2 prothrombinase messenger RNA expression in gravid and nongravid human myometrium

OBJECTIVE

Thrombin is a potent uterotonic agent that may play an important role in human parturition. FGL2 is a prothrombinase that cleaves prothrombin to thrombin. The purpose of this study was to determine FGL2 messenger RNA expression in human myometrium and to assess its relationship to the expression of EP3-6 prostaglandin receptor and inducible nitric oxide synthase.

STUDY DESIGN

Myometrium was obtained from gravid women who underwent cesarean delivery (n = 19), from premenopausal (n = 10) and menopausal (n = 10) women who underwent hysterectomy, and from nonpregnant women who received 200 mg of misoprostol vaginally 12 hours before hysterectomy (n = 8). FGL2 messenger RNA expression was determined with the use of semiquantitative polymerase chain reaction and was compared with previously determined messenger RNA expression levels for EP3-6 and inducible nitric oxide synthase for the same samples. Statistical analysis was performed with the use of independent t test, Fisher exact test, analysis of variance, and linear regression, where appropriate.

RESULTS

All samples that were analyzed contained demonstrable quantities of FGL2 messenger RNA. The highest FGL2 expression was found in gravid women, followed by women who were treated with misoprostol, by premenopausal nonpregnant women, and by menopausal women (P <.0001, analysis of variance). Significantly higher levels of FGL2 expression were found in the gravid women compared with the women who were treated with misoprostol (P <.001), the premenopausal nonpregnant women (P <.001), and the menopausal women (P <.0001). FGL2 messenger RNA expression correlated with EP3-6 and inducible nitric oxide synthase expression in all samples combined (r = 0.55, P <.0001; and r = 0.67, P <.001, respectively).

CONCLUSION

The expression of FGL2 messenger RNA is increased in gravid myometrium compared with nonpregnant samples. Its expression significantly correlates to EP3-6 and inducible nitric oxide synthase expression. FGL2 prothrombinase expression may mediate the role of thrombin in human parturition.

Development of the utero-placental circulation: the role of carbon monoxide and nitric oxide in trophoblast invasion and spiral artery transformation

It is now well known that in order to establish human hemochorial placentation and to provide a progressive increase in blood supply to the growing fetus, the uterine spiral arteries must undergo considerable alterations. This physiological modification is thought to be brought about by the interaction of invasive cytotrophoblast with the spiral artery vessel wall. Despite intensive research our understanding of the mechanisms that control human trophoblast invasion in normal, let alone abnormal pregnancy, are sill poorly understood. This is partly due to difficulties in obtaining "true" placental bed biopsies and most investigators have relied on in vitro models of trophoblast invasion. This article describes the morphological changes that occur within the placental bed throughout human pregnancy along with a review of the various studies which have attempted to sample the placental bed. Thereafter, follows a review of the evidence that invasive trophoblast can release the vasoactive agents nitric oxide and/or carbon monoxide which, in turn, could contribute to early physiological changes in spiral arteries prior to destruction of the smooth muscle within the vessel wall. Current evidence supports the idea that trophoblast-derived carbon monoxide may contribute to spiral artery modification. In contrast there is no evidence for a similar role by nitric oxide.

Effects of hypoxia on heme oxygenase expression in human chorionic villi explants and immortalized trophoblast cells

Although hypoxia induces heme oxygenase (HO)-1 protein and mRNA expression in many cell types, hypoxia has also been shown to decrease HO-1 mRNA and protein expression. We tested the hypothesis that 24-h preexposure to hypoxia in human placental preparations suppresses HO protein expression and enzymatic function. Immortalized HTR-8/SVneo first-trimester trophoblast cells and explants of normal human chorionic villi (CV) from term placentas were cultured for 24 h in 1%, 5%, or 20% O(2). HO protein levels were determined by Western blot analysis, and microsomal HO activity was measured. HO-2 protein content was decreased by 17% and 5% in human trophoblast cells after 24-h exposure to 1% and 5% O(2), respectively, versus 20% O(2). In contrast, HO-2 protein content in CV explants was unaffected by changes in oxygenation. HO-1 protein content, which was barely detectable in both biological systems, was not affected by changes in oxygenation. Similarly, HO enzymatic activity was unchanged in both preparations after 24-h exposure to 1%, 5%, or 20% O(2). The above data do not support the hypothesis that hypoxia in the human placenta suppresses both HO protein content and HO protein function. The present observations reinforce the necessity to determine both HO protein expression and function.

Effects of chronic administration of a heme oxygenase substrate or inhibitor on progression of the estrous cycle, pregnancy and lactation of Sprague-Dawley rats

The purpose of this study was to investigate whether a heme oxygenase substrate (hemin) or an inhibitor (chromium mesoporphyrin IX; CrMP) had any effect on the normal course of the estrous cycle, pregnancy, parturition or lactation in rats. The hypothesis was that these agents, acting on HO to increase or decrease endogenous production of carbon monoxide (CO) respectively, would disrupt these reproductive processes. The results showed that hemin administered s.c. at 30 micromoles/kg for 10 or 11 days, did not markedly influence the estrous cycle; whereas CrMP blocked the estrous cycle in a dose dependant fashion. At 2 and 4 micromoles/kg for 11 days CrMP significantly reduced the occurrence of estrus phase of the estrous cycle and the effect continued after the treatments were discontinued, while a dose of 1 micromole/kg produced no significant effects. CrMP, administered at 4 micromoles/kg during days 5-14 of pregnancy, led to massive fetal resorption with no live births from 14 successfully mated rats. Administration of hemin at 30 micromoles/kg for 10 days during lactation did not have any effect on milk production, whereas administration of CrMP at 4 micromoles/kg significantly decreased lactational performance which was attributed to milk production and not to suckling intensity of the pups. From these observations we conclude that heme oxygenase, and presumably endogenous CO, play positive roles in female reproductive processes and lactation in the rat.

Regulation of connexin 43 by nitric oxide in primary uterine myocytes from term pregnant women

OBJECTIVE

Our purpose was to test the hypothesis that nitric oxide signals regulate the expression of the gap-junction protein connexin 43 in primary uterine myocytes from pregnant women at term.

STUDY DESIGN

Northern analysis and immunoblotting were used to determine the expression of connexin 43 in myocytes cultured in the presence of the nitric oxide donors S -nitroso-N -acetyl-penicillamine (SNAP) (100 micromol/L) and (Z)-1-[2-(2-aminoethyl)-N -(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate diethylenetriamine (NOC-18) (100 micromol/L). We also tested the effect of the NO stimulants 8-bromo-cyclic adenosine 3',5'-monophosphate (cAMP) (100 micromol/L) and 8-bromo-cyclic guanosine 3',5'-monophosphate (cGMP) (200 micromol/L), and the nitric oxide synthase inhibitors N -nitro-L-arginine methyl ester (NAME) (100 micromol/L) and L -N (1-iminoethyl)lysine (NIL) (50 micromol/L).

RESULTS

Nitric oxide and 8-bromo-cAMP reduced the level of connexin 43 expression, and 8-bromo-cGMP had no effect. In contrast, NIL, but not NAME, increased the levels of connexin 43 protein without affecting the level of connexin 43 messenger RNA. With immunoblotting, expression of inducible nitric oxide synthase was not detected in these cells.

CONCLUSION

Nitric oxide down-regulates the expression of connexin 43 in cultured human myocytes. We speculate that this effect may decrease the efficacy of intermyocyte signaling and thus contribute to uterine quiescence during human pregnancy.

The expression of EP3-6 and inducible nitric oxide synthase messenger RNA are correlated in pregnant and misoprostol-treated but not in nongravid or menopausal myometrium

OBJECTIVE

Our purpose was to investigate the expression level of inducible nitric oxide synthase (iNOS) in nongravid and gravid human myometrium and assess its relation to the expression of EP3 prostaglandin receptor isoforms.

STUDY DESIGN

Myometrial tissue from a cohort of gravid, nongravid, and menopausal subjects and from nongravid subjects exposed to misoprostol was obtained and analyzed for iNOS messenger RNA (mRNA) expression and compared with previously determined mRNA levels for the EP3-6 prostaglandin receptor from the same samples by means of semiquantitative polymerase chain reaction.

RESULTS

Significantly higher levels of iNOS mRNA expression were found in the gravid compared with premenopausal nongravid (P <.02) and menopausal (P <.05,) samples. Linear regression analysis of iNOS versus EP3-6 expression showed a positive correlation between all studied samples (n = 47, P <.0001, r = 0.815). Among individual groups, a significant linear correlation was found only in pregnant (n = 10, P <.0001, r = 0.785) and misoprostol-exposed (n = 7, P =.0256, r = 0.815) subjects. No correlation between iNOS and EP3-6 mRNA levels was noted in the nongravid premenopausal groups (n = 10, P =.205, r = 0.350), although a nonsignificant trend was found for the menopausal group (n = 10, P =.0535, r = 0.624). When the data from pregnant patients were stratified, both laboring and nonlaboring women displayed the observed correlation (n = 6, P <.0001, r = 0.993; and n = 13, P =.008, r = 0.697, respectively).

CONCLUSION

iNOS and EP3-6 expression are strongly correlated in gravid and misoprostol-treated, nongravid myometrium.

Analysis of inflammatory gene induction by oxidized phospholipids in vivo by quantitative real-time RT-PCR in comparison with effects of LPS

Oxidized phospholipids are thought to play a role in the development of atherosclerosis and other chronic inflammatory processes. In this study, we analyzed the expression of inflammatory genes induced by oxidized L-alpha-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholin (OxPAPC) in vitro and in vivo using quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Cultured human umbilical vein endothelial cells (HUVEC) and monocyte-like U937 cells were treated with OxPAPC or lipopolysaccharide (LPS) for 3 h. For in vivo studies, OxPAPC or LPS was injected intravenously into female C57Bl/6J mice and different tissues were isolated after 3 h. We found that both OxPAPC and LPS induced expression of early growth response factor 1 (EGR-1) and monocyte chemoattractant protein 1 (MCP-1) in HUVEC and of JE, the mouse homologue of MCP-1, in liver and heart. Interestingly, OxPAPC but not LPS increased expression of heme oxygenase 1 (HO-1) in U937 cells, HUVEC, aorta, heart, liver, and isolated blood cells. In contrast, E-selectin was selectively induced by LPS, but not by OxPAPC. Finally, OxPAPC-induced expression of HO-1 was blocked by a platelet-activating factor (PAF) receptor antagonist. We conclude that oxidized phospholipids are biologically active in vivo and exert a specific response inducing a pattern of genes that is different from that induced by LPS. In addition, we demonstrate that the quantitative real-time RT-PCR technology is a proper tool to investigate differential inflammatory gene induction in vivo.

Heme oxygenase expression in human placenta and placental bed: reduced expression of placenta endothelial HO-2 in preeclampsia and fetal growth restriction

In this study we tested the hypothesis that expression of heme oxygenases HO-1 and HO-2, which are responsible for the production of carbon monoxide, are reduced in the placenta and placental bed of pregnancies complicated by preeclampsia (PE) and fetal growth restriction (FGR) compared with control third-trimester pregnancies. Placental protein expression was determined by Western blotting (n=10 in each group) and immunohistochemistry (controls n=18, PE n=19, FGR n=10). Extravillous trophoblast expression was determined by immunohistochemistry of placental bed biopsy samples (controls n=17, PE n=19, FGR n=10). Western blot analysis of placental homogenates showed no overall differences in HO-2 among groups. However, immunohistochemical analysis showed a reduction in HO-2 expression in endothelial cells in both abnormal groups (PE P<0.01; FGR P<0.0005 vs. control group) but no differences in villous trophoblast staining. HO-1 was undetectable by Western blotting in control and abnormal pregnancies and immunoreactivity was very low, suggesting that there is little HO-1 in the placenta. Within the placental bed, HO-2 but not HO-1 was detected on all populations of extravillous trophoblast, but expression of HO-2 or HO-1 did not change in PE or FGR. The reduced expression of HO-2 on endothelial cells in PE and FGR may be responsible for reduced placental blood flow in these conditions. The data do not show changes in HO in the placental bed in PE or FGR.

Relaxation of myometrium by calcitonin gene-related peptide is independent of nitric oxide synthase activity in mouse uterus

Calcitonin gene-related peptide (CGRP) inhibits myometrial contractile activity. However, the responsiveness of the mouse myometrium to CGRP is dependent on the hormonal and gestational stage. The inhibitory effect of CGRP in the myometrium is prominent during gestation and declines at parturition. The present study was undertaken to examine if nitric oxide (NO) production by nitric oxide synthase (NOS) isoforms mediates the inhibitory action of CGRP on uterine contractions as has been suggested earlier. Transgenic mice deficient in either of the three major NOS isoforms: endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) were used. Isometric force measurements on myometrial strips obtained from NOS-deficient mice were carried out and the inhibitory capacity of CGRP was monitored. CGRP inhibited KCl-induced contractions of the myometrial strips obtained from eNOS(-/-), iNOS(-/-), and nNOS(-/-) mice with equal efficiency as in wild-type animals. Additionally, NOS protein expression in the mouse uterus during gestation and during the estrous cycle was examined by means of Western immunoblot analysis. No correlation between NOS expression and inhibitory activity of CGRP was evident. The results suggest that the inhibitory action of CGRP in the mouse uterus is independent of the activity of these NOS isoforms.

Hemeoxygenase expression in human placenta and placental bed implies a role in regulation of trophoblast invasion and placental function

The purpose of this study was to examine the expression of hemeoxygenases HO-1 and HO-2, which are responsible for the production of carbon monoxide (CO), in the human placenta and placental bed and to determine the role of inhibitors of HO on placental perfusion pressure. We hypothesized that HO is expressed within the placenta and that invading cytotrophoblast cells (CTB) express HO isoforms. The expression of HO-1 and HO-2 was studied on placenta and placental bed biopsies, obtained using a transcervical sampling technique, from normal human pregnancies between 8 and 19 wk gestation and at term. In the placenta, HO-2 immunostaining was prominent in syncytiotrophoblast in the first trimester and reduced toward term (P<0.0005). HO-2 endothelial immunostaining was weak in the first trimester, but increased by term (P<0.0005). Within the placental bed, HO-2 was expressed by CTB in cell columns, the cytotrophoblast shell, and cell islands. Both intravascular CTB and interstitial CTB expressed HO-2. HO-1 immunostaining was low in the placenta but intense on the CTB within the placental bed. A striking feature was the absence of HO-1 from the proximal layers of cell columns, with strong expression on the more distal CTB layers of the cell columns. In placental perfusion studies, a significant dose-dependent increase in perfusion pressure was observed in the presence of zinc protoporphyrin, an inhibitor of HO. These results suggest a role for CO in placental function, trophoblast invasion, and spiral artery transformation. Hemeoxygenase expression in human placenta and placental bed implies a role in regulation of trophoblast invasion and placental function.