Human chorionic gonadotropin induces nitric oxide synthase mRNA in mouse peritoneal macrophages

Immune-endocrine crosstalk during pregnancy

The success of pregnancy depends mostly on a synchronized immune-endocrine crosstalk at the maternal-fetal interface. Hormones are important in terms of maintaining the suitable environment and sufficient nutrition for the developing fetus. They also play a major role during the process of parturition and lactation. Maternal immunomodulation is important for the tolerance of semiallogeneic fetus. This is achieved in concert with a variety of endocrine stimulation. Estrogen, progesterone, and Human Chorionic Gonadotropin play a major role in immune modulation during pregnancy. Hormones modulate B cells, dendritic cells, uterine natural killer cells, macrophages, neutrophils to adopt fetal friendly immune phenotypes. Recently the use of hormones in assisted reproductive technology has been found to improve the pregnancy outcome. The present review focuses on the pregnancy-related hormones, their role in immunomodulation for successful pregnancy outcome. This also shed light on the immune-endocrine crosstalk at maternal-fetal interface during pregnancy.

Involvement of Luteinizing Hormone in Alzheimer Disease Development in Elderly Women

Alzheimer disease (AD) is a slow progressive neurodegenerative disease that affects more elderly women than elderly men. It impairs memory, typically progresses into multidomain cognitive decline that destroys the quality of life, and ultimately leads to death. About 5.3 million older Americans are now living with this disease, and this number is projected to rise to 14 million by 2050. Annual health-care costs in the United States alone are projected to increase to about US$1.1 trillion by 2050. The initial theory that decreasing estrogen levels leads to AD development in postmenopausal women has been proven inconclusive. For example, Women's Health Research Initiative Memory Study and the population-based nested case-control study have failed to demonstrate that estrogen/progesterone (hormone replacement therapy [HRT]) or estrogen replacement therapy could prevent the cognitive decline or reduce the risk of AD. This led to the realization that AD development could be due to a progressive increase in luteinizing hormone (LH) levels in postmenopausal women. Accordingly, a large number of studies have demonstrated that an increase in LH levels is positively correlated with neuropathological, behavioral, and cognitive changes in AD. In addition, LH has been shown to promote amyloidogenic pathway of precursor protein metabolism and deposition of amyloid β plaques in the hippocampus, a region involved in AD. Cognate receptors that mediate LH effects are abundantly expressed in the hippocampus. Reducing the LH levels by treatment with gonadotropin-releasing hormone agonists could provide therapeutic benefits. Despite these advances, many questions remain and require further research.

Endocrine factors modulating immune responses in pregnancy

How the semi-allogeneic fetus is tolerated by the maternal immune system remains a fascinating phenomenon. Despite extensive research activity in this field, the mechanisms underlying fetal tolerance are still not well understood. However, there are growing evidences that immune–immune interactions as well as immune–endocrine interactions build up a complex network of immune regulation that ensures fetal survival within the maternal uterus. In the present review, we aim to summarize emerging research data from our and other laboratories on immune modulating properties of pregnancy hormones with a special focus on progesterone, estradiol, and human chorionic gonadotropin. These pregnancy hormones are critically involved in the successful establishment, maintenance, and termination of pregnancy. They suppress detrimental maternal alloresponses while promoting tolerance pathways. This includes the reduction of the antigen-presenting capacity of dendritic cells (DCs), monocytes, and macrophages as well as the blockage of natural killer cells, T and B cells. Pregnancy hormones also support the proliferation of pregnancy supporting uterine killer cells, retain tolerogenic DCs, and efficiently induce regulatory T (Treg) cells. Furthermore, they are involved in the recruitment of mast cells and Treg cells into the fetal–maternal interface contributing to a local accumulation of pregnancy-protective cells. These findings highlight the importance of endocrine factors for the tolerance induction during pregnancy and encourage further research in the field.

In anesthetized pigs human chorionic gonadotropin increases myocardial perfusion and function through a β-adrenergic-related pathway and nitric oxide

Human chorionic gonadotropin (hCG) is not only responsible for numerous pregnancy-related processes, but can affect the cardiovascular system as well. So far, however, information about any direct effect elicited by hCG on cardiac function, perfusion, and the mechanisms involved has remained scarce. Therefore, the present study aimed to determine the primary in vivo effect of hCG on cardiac contractility and coronary blood flow and the involvement of autonomic nervous system and nitric oxide (NO). Moreover, in coronary endothelial cells (CEC), the intracellular pathways involved in the effects of hCG on NO release were also examined. In 25 anesthetized pigs, intracoronary 500 mU/ml hCG infusion at constant heart rate and aortic blood pressure increased coronary blood flow, maximum rate of change of left ventricular systolic pressure, segmental shortening, cardiac output, and coronary NO release (P < 0.0001). These hemodynamic responses were graded in a further five pigs. Moreover, while blockade of muscarinic cholinoceptors (n = 5) and of α-adrenoceptors (n = 5) did not abolish the observed responses, β1-adrenoceptors blocker (n = 5) prevented the effects of hCG on cardiac function. In addition, β2-adrenoceptors (n = 5) and NO synthase inhibition (n = 5) abolished the coronary response and the effect of hCG on NO release. In CEC, hCG induced the phosphorylation of endothelial NO synthase through cAMP/PKA signaling and ERK1/2, Akt, p38 MAPK involvement, which were activated as downstream effectors of β2-adrenoceptor stimulation. In conclusion, in anesthetized pigs, hCG primarily increased cardiac function and perfusion through the involvement of β-adrenoceptors and NO release. Moreover, cAMP/PKA-dependent kinases phosphorylation was found to play a role in eliciting the observed NO production in CEC.

Human chorionic gonadotrophin (hCG) enhances immunity against L. tropica by stimulating human macrophage functions

During pregnancy, there are important changes in hormone levels such as the huge production of human chorionic gonadotropin (hCG), which is supposed to influence the immune system. The aim of this study was to investigate the effect of hCG on immune response against Leishmania, through the evaluation of the functions of human macrophages infected with L. tropica. This study demonstrated that hCG significantly increased the NO production by rHu-IFNγ-primed macrophages then infected with L. tropica, which was correlated with decrease in the number of infected macrophages as well as the number of amastigotes per macrophage in a dose-dependent manner; however, the greatest effect was shown with the 250 U/mL concentration. The addition of the same concentration of hCG to rHu-IFNγ-primed macrophages caused also a major increase in both IL-6 and IL-12p40 production. In conclusion, hCG enhances different macrophage functions involved in immunity against L. tropica.

Why does the fallopian tube fail in ectopic pregnancy? The role of activins, inducible nitric oxide synthase, and MUC1 in ectopic implantation

OBJECTIVE

To investigate the role of activin-βA subunit, activin type II receptors, inducible nitric oxide synthase (iNOS), and MUC1 in the pathogenesis of ectopic pregnancy (EP) and their involvement in the determination of the implantation site.

DESIGN

Observational study.

SETTING

Academic unit of reproductive and developmental medicine.

PATIENT(S)

Four women at the luteal phase, three pseudopregnant women at the time of hysterectomy for benign disease, and 10 archived cases of EP. We collected 14 Fallopian tubes were collected from four women at the luteal phase and three pseudopregnant women at the time of hysterectomy for benign disease; specimens from implantation site, trophoblast and remote sites from the implantation site were collected from 10 archived cases of EP.

INTERVENTION(S)

Immunohistochemistry and quantitative reverse-transcriptase polymerase chain reaction (RT-PCR).

MAIN OUTCOME MEASURE(S)

Comparison of the expression of candidate molecules between the different groups.

RESULT(S)

The expression of activin-βA subunit, activin type II receptors, and iNOS was statistically significantly increased and expression of MUC1 statistically significantly decreased in tubes bearing an EP. There was no statistically significant difference in the expression of the candidate molecules between the implantation and remote sites. Candidate molecules were also expressed in the trophoblast.

CONCLUSION(S)

The pathological expression of candidate molecules by tubes bearing an EP is not involved in the determination of implantation site. Additionally, candidate molecules may play a role in the regulation of trophoblast cells in vivo during early pregnancy.

Alcohol-fermented soybean increases the expression of receptor-interacting protein 2 and IκB kinase β in mouse peritoneal macrophages

Soybean is a useful component of traditional Korean medicine with well-documented health-promoting effects. We investigated the effects of alcohol-fermented soybean (AFS) on immune function. When AFS treatment was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of nitric oxide (NO) and tumor necrosis factor (TNF)-α production in mouse peritoneal macrophages. AFS increased the expression of inducible NO synthase mRNA and protein in rIFN-γ-primed macrophages. Treating macrophages with pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-κB (NF-κB), decreased the synergistic effects of AFS. In addition, AFS in combination with rIFN-γ increased the phosphorylation of p38 and c-Jun N-terminal kinase (JNK) but not extracellular signal-regulated kinase. However, AFS had no effect on phosphorylation of mitogen-activated protein kinases by itself. The p38 inhibitor SB203580 or the JNK inhibitor SP600125 inhibited the AFS-induced NO and TNF-α production. When AFS was used in combination with rIFN-γ, there was a co-operative activation of NF-κB and receptor-interacting protein 2 (Rip2)/IκB kinase (IKK)-β. Our results indicate that AFS increases the production of NO and TNF-α through the activation of Rip2/IKK-β in rIFN-γ-primed macrophages.

Water extract isolated from Chelidonium majus enhances nitric oxide and tumour necrosis factor-α production via nuclear factor-κB activation in mouse peritoneal macrophages

Chelidonium majus is used to treat several inflammatory diseases and tumours. We have examined the effect of C. majus on nitric oxide (NO) production using mouse peritoneal macrophages. When C. majus was used in combination with recombinant interferon-γ (rIFN-γ, 10U mL−1), there was a marked cooperative induction of NO production. Treatment of rIFN-γ plus C. majus (1 mg mL−1) in macrophages caused a significant increase in tumour necrosis factor-α (TNF-α) production. The increased production of NO and TNF-α from rIFN-γ plus C. majus-stimulated cells was almost completely inhibited by nuclear factor-κB (NF-κB) inhibitor, pyrrolidine dithiocarbamate (100 μM). These findings demonstrated that C. majus increased the production of NO and TNF-α by rIFN-γ-primed macrophages and suggested that NF-κB played a critical role in mediating the effects of C. majus.

Chorionic gonadotropin alleviates thioglycollate-induced peritonitis by affecting macrophage function

Human chorionic gonadotrophin (hCG) is a hormone produced during pregnancy and present at the implantation site and in the maternal blood. Pregnancy has been proposed to represent a controlled state of inflammation at an early stage at the implantation site and later, systemically extended to the maternal circulation. Earlier, we reported that hCG can inhibit the development of diabetes in NOD mice and LPS-induced septic shock in a murine model. We hypothesize that hCG can contribute to the reduction of inflammation by modifying Mphi function. Here, the TG-induced peritonitis model for inflammation was used to investigate the effect of hCG on cytokine production and cell recruitment in vivo. hCG pretreatment in TG-induced peritonitis increased the number of peritoneal cells, especially PMN and monocytes, compared with mice injected with TG only. This increased cell number was partially explained by increased cell survival induced by hCG. Despite the cellular infiltrate, hCG pretreatment decreased i.p. TNF-alpha, IL-6, PTX3, CCL3, and CCL5 levels. By depleting peritoneal resident Mphi using clodronate liposomes prior to the application of hCG and the TG trigger, we established that Mphi are the main responsive cells to hCG, as the suppressed TNF-alpha and IL-6 production and increased PMN influx are abolished in their absence. Together, these data suggest that hCG contributes to the controlled inflammatory state of pregnancy by regulating Mphi proinflammatory function.

Expression of inducible nitric oxide synthase by Corydalis turtschaninovii on interferon-gamma stimulated macrophages

AIM OF THE STUDY

Corydalis turtschaninovii (CT) has been used for tumor therapy. However, it is still unclear how this herb prevents the diseases in experimental models. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of tumors has received increasing attention.

MATERIALS AND METHODS

In this study, using mouse peritoneal macrophages, we have examined the mechanism by which CT regulates NO production.

RESULTS

When CT was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. However, CT had no effect on NO production by itself. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. The increased production of NO from rIFN-gamma plus CT-stimulated peritoneal macrophages was decreased by the treatment with N(G)-monomethyl-L-arginine or N(alpha)-Tosyl-Phe Chloromethyl Ketone, iNOS inhibitor. The increased production of NO from rIFN-gamma plus CT-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappa B (NF-kappaB). However, treatment of peritoneal macrophages with rIFN-gamma plus CT had no effect on the increase in tumor necrosis factor-alpha (TNF-alpha) production.

CONCLUSIONS

Our findings demonstrate that CT increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of CT.

Leonurus sibiricusinduces nitric oxide and tumor necrosis factor-α in mouse peritoneal macrophages

Using mouse peritoneal macrophages, we have examined the mechanism by which Leonurus sibiricus (LS) regulates nitric oxide (NO) production. When LS was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of NO production; however, LS by itself had no effect on NO production. The increased production of NO from rIFN-γ plus LS-stimulated cells was almost completely inhibited by pretreatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor κB. Furthermore, treatment of peritoneal macrophages with rIFN-γ plus LS caused a significant increase in tumor necrosis factor-α (TNF-α) production. PDTC also decreased the effect of LS on TNF-α production significantly. Because NO and TNF-α play an important role in immune function and host defense, LS treatment could modulate several aspects of host defense mechanisms as a result of stimulation of the inducible nitric oxide synthase.

Chorionic gonadotropin can enhance innate immunity by stimulating macrophage function

Human chorionic gonadotropin (hCG) is a placental glycoprotein, mainly secreted by trophoblasts during pregnancy. Its function in endocrine regulation has been well documented, but its immunological role is still largely unclear. For a successful pregnancy, an effective innate immunity is needed to protect the mother and fetus against infection, while maintaining tolerance against the paternal antigens of the fetus. The aim of this study was to investigate the effect of hCG on the function of macrophages (Mvarphi), which are major players in the innate response. hCG treatment of IFN-gamma-primed Mvarphi resulted in increased production of NO, reactive oxygen species, IL-6 and IL-12p40, and enhanced phagocytosis of apoptotic cells. hCG treatment did not affect the induction of allogeneic T cell proliferation by IFN-gamma-primed Mvarphi. The observed effects were receptor-mediated and involved the protein kinase A signaling pathway, as indicated by blocking studies using specific inhibitors. In vivo thioglycollate-elicited Mvarphi also exhibited increased phagocytic ability upon IFN-gamma activation and hCG treatment. In conclusion, hCG enhances Mvarphi functions involved in innate immunity, while the capacity to stimulate allogeneic T cells remains unchanged.

Reproductive hormones modulate oxidative stress in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by gradual cognitive decline, impairments in speech and language, and dysfunction in the sensorimotor systems, culminating in complete reliance on nursing care. Oxidative stress, caused by an imbalance in the pro-oxidant/antioxidant mechanisms in the body, has been implicated in AD pathogenesis, as in many other age-associated diseases such as atherosclerosis, Parkinson disease, and amyotrophic lateral sclerosis. Although the hormones estrogen, progesterone, testosterone, and luteinizing hormone are best known for their roles in reproduction, many studies show these hormones have other roles, including neuroprotection. Changes in the levels of these hormones that occur in reproductive senescence are hypothesized to increase risk of AD, as a result of reduced protection against oxidative insults. The Abeta peptide, overproduction of which is thought to be a key pathogenic event in the development of AD, is neurotoxic, most likely due to its ability to promote oxidative stress. The reproductive hormones are known to influence Abeta metabolism, and this review discusses the beneficial and detrimental effects these hormones have on Abeta production and oxidative stress, and their relevance in potential AD therapies.

Solanum nigrum produces nitric oxide via nuclear factor-kappaB activation in mouse peritoneal macrophages

Nitric oxide (NO) is an antitumour molecule produced in activated macrophages and Solanum nigrum is a plant used in oriental medicine to treat tumours. In this study using mouse peritoneal macrophages, we have examined the mechanism by which Solanum nigrum regulates NO production. When Solanum nigrum was used in combination with 20 U/ml of recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. The production of NO from rIFN-gamma plus Solanum nigrum-stimulated peritoneal macrophages was decreased by treatment with N-monomethyl-L-arginine or N-tosyl-Phe chloromethyl ketone, an iNOS inhibitor. Additionally, the increased production of NO from rIFN-gamma plus Solanum nigrum-stimulated cells was almost completely inhibited by pretreatment with 100 micromol/l of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappaB (NF-kappaB). Furthermore, Solanum nigrum increased activation of NF-kappaB. These findings suggest that Solanum nigrum increases the production of NO by rIFN-gamma-primed macrophages and NF-kappaB plays a critical role in mediating these effects.

Production of nitric oxide and tumor necrosis factor-alpha by Smilacis rhizoma in mouse peritoneal macrophages

Using mouse peritoneal macrophages, we have examined the mechanism by which, Smilacis rhizoma (SR) regulates nitric oxide (NO) production. When SR was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. However, SR had no effect on NO production by itself. The increased production of NO from rIFN-gamma plus SR-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus SR caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effect of SR on TNF-alpha production significantly. These findings demonstrate that SR increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of SR.

Macrophages in human reproductive tissues contain luteinizing hormone/chorionic gonadotropin receptors

PROBLEM

To determine whether macrophages in human reproductive tissues contain luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor mRNA and receptor protein that can bind 125I-hCG.

METHOD OF STUDY

Macrophages isolated from term pregnancy human decidua were used for LH/hCG receptor detection by in situ hybridization for receptor mRNA and immunocytochemistry for a macrophage marker, CD68, performed alone and in combination, reverse transcription-nested polymerase chain reaction, Western and ligand blotting. The LH/hCG receptor presence in macrophages in late luteal phase human endometria and corpora lutea was determined by sequential performance of in situ hybridization and immunocytochemistry.

RESULTS

The macrophages present in term pregnancy human decidua and late luteal phase human endometria and corpora lutea contain LH/hCG receptors.

CONCLUSIONS

This is the first demonstration of macrophages present in human reproductive tissues containing LH/hCG receptors. The receptor presence suggests that LH and hCG may regulate macrophage functions in gonadal as well as in non-gonadal target tissues.

Induction of nitric oxide synthase by Oldenlandia diffusa in mouse peritoneal macrophages

Oldenlandia diffusa (OD) has been used to treat malignant tumors. In this study using mouse peritoneal macrophages, we have examined the mechanism by which OD regulates nitric oxide (NO) production. When OD (1 mg/ml) was used in combination with 10 U/ml of recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production (36.13+/-7.12 microM) by the Griess method (nitrite). Treatment of macrophages with rIFN-gamma plus OD (1 mg/ml) caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production (4.49+/-1.43 ng/ml) by enzyme-linked immunosorbent assay. The increased production of NO and TNF-alpha from rIFN-gamma-plus OD-stimulated cells was almost completely inhibited by pretreatment with 100 microM of pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). PDTC also inhibited phosphorylation of IkappaB in rIFN-gamma-plus OD-stimulated cells. These findings demonstrate that OD increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of OD.

CancerB increases production of nitric oxide and tumor necrosis factor-alpha in peritoneal macrophages

BACKGROUND

CancerB (CCB, IMSF-5), herbal combination, may be able to stimulate potential toxic mediators such as nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) in isolated mouse peritoneal macrophages.

METHODS

NO production was determined by Griess method, and TNF-alpha production by enzyme-linked immunosorbent assay. Amounts of proteins were observed by Western blotting.

RESULTS

CCB had no effect on NO production by itself, but CCB alone did stimulate the production of TNF-alpha. When CCB was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production, TNF-alpha production and NF-kappa B activation. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase protein. The increased production of NO from rIFN-gamma plus CCB-stimulated peritoneal macrophages was decreased by the treatment with N(G)-monomethyl-L-arginine or N(alpha)-Tosyl-Phe Chloromethyl Ketone. Nuclear factor-kappa B (NF-kappa B) inhibitor, pyrrolidine dithiocarbamate was able to completely inhibit the production of NO and TNF-alpha.

CONCLUSIONS

These findings demonstrate that CCB increases the production of NO and TNF-alpha by rIFN-gamma-primed peritoneal macrophages and suggest that NF-kappa B plays a critical role in mediating these effects of CCB.

Activation of inducible nitric oxide synthase by Euonymus alatus in mouse peritoneal macrophages

BACKGROUND

Euonymus alatus (EA) has been used for tumor therapy. However, it is still unclear how this herb prevents the diseases in experimental models. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of tumors has received increasing attention.

METHODS

Using mouse peritoneal macrophages, we have examined the mechanism by which EA regulates NO production.

RESULTS

When EA was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. However, EA had no effect on NO production by itself. The increased production of NO from rIFN-gamma plus EA-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus EA caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effects of EA on TNF-alpha production significantly.

CONCLUSIONS

EA increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of EA.

Nitric oxide production by high molecular weight water-soluble chitosan via nuclear factor-kappaB activation

High molecular weight water-soluble chitosan (WSC), having an average molecular weight of 300000 Da and a degree of deacethylation over 90%, can be produced using a simple multi-step membrane separation process. In this study, the effect of WSC on the production of nitric oxide (NO) in RAW 264.7 macrophages was evaluated. Water-insoluble chitosan alone has been previously shown to exhibit in vitro stimulatory effect on macrophages NO production. However, WSC had no effect on NO production by itself. When WSC was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of WSC on NO synthesis was shown 24 h after treatment with rIFN-gamma. The increased production of NO from rIFN-gamma plus WSC-stimulated RAW 264.7 macrophages was decreased by the treatment with N(G)-monomethyl-L-arginine (N(G)MMA). The increase in NO synthesis was reflected, as an increased amounts of inducible NO synthase protein. In addition, synergy between rIFN-gamma and WSC was mainly dependent on WSC-induced tumor necrosis factor-alpha (TNF-alpha) and nuclear factor-kappaB (NF-kappaB) activation. The present results indicate that the capacity of WSC to increase NO production from rIFN-gamma-primed RAW 264.7 macrophages is the result of WSC-induced TNF-alpha secretion via the signal transduction pathway of NF-kappaB activation.

Human chorionic gonadotropin induces nitric oxide synthesis by murine microglia

This study investigated the effects of human chorionic gonadotropin (hCG) on the synthesis of nitric oxide (NO) in murine neonatal microglial cells. When hCG was used in combination with interferon-gamma (IFN-gamma), there was a marked cooperative induction of NO synthesis in a dose-dependent manner. This increase in NO synthesis was reflected as an increased amount of iNOS protein. The increase of NO synthesis by IFN-gamma-plus-hCG was associated with the increase of tumor necrosis factor-alpha (TNF-alpha) secretion and hCG-induced NO production was decreased by the treatment with anti-murine TNF-alpha neutralizing antibody. This study provides evidence that hCG activates expression of iNOS protein in murine microglial cells accompanied by NO accumulation via pathway dependent on L-arginine in the culture medium, and further offers that TNF-alpha acts on the NO synthesis from IFN-gamma-primed murine microglial cells.

The nitric oxide-producing properties of Solanum lyratum

We examined the effect of Solanum lyratum Thunb. (Solanaceae) (SL) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with SL after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. SL had no effect on NO synthesis by itself. When SL was used in combination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of SL on NO synthesis was shown 6 h after treatment with rIFN-gamma. The increased production of NO from rIFN-gamma plus SL-stimulated cells was decreased by the treatment with staurosporin. In addition, synergy between rIFN-gamma and SL was mainly dependent on SL-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of SL were endotoxin free. The present results indicate that the capacity of SL to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of SL-induced TNF-alpha secretion via the signal transduction pathway of PKC activation.

Production of nitric oxide in mouse peritoneal macrophages after priming with interferon-gamma by the stem of Sinomenium acutum

The present study demonstrates that the aqueous extract of Sinomenium acutum stem (SSAE) produces nitric oxide (NO) upon treatment with recombinant interferon gamma (rIFN-gamma) in mouse peritoneal macrophages. Apparently SSAE has no effect on NO production by itself. This production is dependent on L-arginine and can be inhibited by the L-arginine analogue N(G)-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus SSAE-stimulated cells was decreased by the treatment of protein kinase C inhibitor. Tumor necrosis factor-alpha (TNF-alpha) has been shown to stimulate the oxidative metabolism of L-arginine to produce NO. Mouse peritoneal macrophages secrete high levels of TNF-alpha after incubation with rIFN-gamma plus SSAE. In addition, SSAE-induced NO production is progressively inhibited by anti-murine TNF-alpha neutralizing antibody. These results show that the capacity of SSAE to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of SSAE-induced TNF-alpha secretion.

The nitric oxide-producing activities of Scutellaria baicalensis

Scutellaria baicalensis (SB) has antibacterial and antiviral activities. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of bacteria, viruses and tumors has received increasing attention. The objective of this study was to determine the effect of SB on the production of NO. Stimulation of mouse peritoneal macrophages with SB after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in the increased NO production. SB had no effect on NO production by itself. When SB was used in combination with rIFN-gamma, there was a marked cooperative induction of NO production in a dose-dependent manner. The optimal effect of SB on NO production was shown 6 h after treatment with rIFN-gamma. NO production by SB was inhibited by N(G)-monomethyl-L-arginine. The increased production of NO from rIFN-(gamma) plus SB-stimulated cells was decreased by the treatment of protein kinase C inhibitor such as staurosporin. In addition, synergy between rIFN-gamma and SB was mainly dependent on SB-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of SB were endotoxin free. These results suggest that the capacity of SB to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of SB-induced TNF-gamma secretion.

Activation of inducible nitric oxide synthase by Taraxacum officinale in mouse peritoneal macrophages

The objective of the current study was to determine the effect of Taraxacum officinale (TO) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with TO after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. TO had no effect on NO synthesis by itself. When TO was used in combination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of TO on NO synthesis was shown 6 h after treatment with rIFN-gamma. This increase in NO synthesis was manifested as an increased amount of inducible NO synthase (iNOS) protein. NO production was inhibited by N(G)-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus TO-stimulated cells was decreased by treatment with a protein kinase C inhibitor such as staurosporin. In addition, synergy between rIFN-gamma and TO was mainly dependent on TO-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of TO were endotoxin free. These results suggest that the capacity of TO to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of TO-induced TNF-alpha secretion.

The nitric oxide-producing properties of Ulmi radicis cortex extract

We investigated the effect of Ulmi radicis cortex extract (UrCE) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with UrCE after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in the increased NO synthesis. UrCE had no effect on NO synthesis by itself. When UrCE was used in combination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of UrCE on NO synthesis was shown 6 h after treatment with rIFN-gamma. NO production was inhibited by NG-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus UrCE-stimulated cells was decreased by the treatment of protein kinase C inhibitor such as staurosporin. In addition, synergy between rIFN-gamma and UrCE was mainly dependent on UrCE-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of UrCE were endotoxin free. These results suggest that the capacity or UrCE to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of UrCE-induced TNF-alpha secretion.

Activation of inducible nitric oxide synthase by Yongdam-Sagan-Tang in mouse peritoneal macrophages

The objective of the current study was to determine the effect of Yongdam-Sagan-Tang (YS-Tang) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with YS-Tang after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. YS-Tang had no effect on NO synthesis by itself. When YS-Tang was used in combination with rIFN-gamma, there was a marked co-operative induction of NO synthesis in a dose-dependent manner. The optimal effect of YS-Tang on NO synthesis was shown 6 h after treatment with rIFN-gamma. This increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. NO production was inhibited by NG-monomethyl-L-arginine. The increased production of NO from rIFN-gamma plus YS-Tang-stimulated cells was decreased by the treatment with staurosporin. In addition, synergy between rIFN-gamma and YS-Tang was mainly dependent on YS-Tang-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of YS-Tang were endotoxin free. These results suggest that the capacity of YS-Tang to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of YS-Tang-induced TNF-alpha secretion.