Effect of weight loss before in vitro fertilization in women with obesity or overweight and infertility: a systematic review and meta-analysis

The effect of weight loss before in vitro fertilization (IVF) procedures on pregnancy outcomes in women with overweight or obesity and infertility remains controversial. In this systematic review and meta-analysis, we investigated whether weight loss before IVF in these women affected the IVF results and reproductive outcomes. PubMed, Embase, and the Cochrane Library databases were searched from the inception dates until December 2022, using combinations of relevant keywords. Only six randomized controlled trials, including 1627 women with obesity or overweight, were analyzed. The weight change in the intensive care group, compared to the control group who underwent IVF without weight loss was - 4.62 kg (mean difference; 95% confidence interval [CI] - 8.10, - 1.14). Weight loss before IVF did not significantly increase the live birth rate in women with obesity or overweight and infertility (odds ratio, 1.38; 95% CI 0.88, 2.10). The clinical pregnancy, miscarriage, ongoing pregnancy, and ectopic pregnancy rates did not differ between the weight loss and control groups before IVF. This meta-analysis demonstrated that even significant weight loss before IVF in women with obesity or overweight and infertility did not improve the live birth, clinical pregnancy, ongoing pregnancy, or ectopic pregnancy rates. PROSPERO Registration Number: CRD42023455800.

Risk of cardiocerebrovascular diseases is increased in Korean women with polycystic ovary syndrome: a nationwide cohort study

To investigate the relationship between polycystic ovary syndrome (PCOS) and risk of cardiocerebrovascular disease in Korean women. This longitudinal cohort study using data from the Korean National Health Insurance Service included the women aged 15-44 years diagnosed with PCOS between 2002 and 2019, and the controls were matched 1:3 by age group, income, and region of residence. The endpoint outcomes of this study were the occurrence of ischemic heart disease, cerebrovascular diseases, and combined cardiocerebrovascular diseases in the PCOS and control groups. A stratified Cox proportional hazards regression analysis for matched data was performed to evaluate the relative hazard of events in the PCOS group compared to that in the control group. Among a total of 549,400 participants in the cohort, 137,416 women had a diagnosis of PCOS and 412,118 women did not have it. During a median follow-up of 54 months (interquartile range, 30-78 months), the incidence rates of all cardiovascular, ischemic heart, and cerebrovascular diseases were 6.6, 4.0, and 2.9, respectively, per 1000 person-years for women with PCOS, and 4.8, 2.8, and 2.3, respectively, per 1000 person-years for healthy control women. Women with PCOS had a higher hazard ratio of 1.224 (95% confidence interval, 1.18-1.27) of the composite cardiocerebrovascular diseases than those in the controls after propensity score matching for confounding variables, including body mass index, diabetes mellitus, hypertension, dyslipidemia, physical exercise level, alcohol consumption, current smoking, systolic and diastolic blood pressures, total cholesterol, and triglyceride levels. Hazard ratio for ischemic heart and cerebrovascular diseases was higher in women with PCOS than in the control group (hazard ratio, 1.254; 95% confidence interval, 1.20-1.31 and hazard ratio, 1.201; 95% confidence interval, 1.14-1.27, respectively). PCOS is associated with an increased risk of cardiocerebrovascular diseases in Korean women irrespective of their obesity. Counselling on the management of long-term risk of cardiovascular diseases should be offered to women with PCOS in East Asian countries where PCOS is characterized by a relatively low BMI.

Cumulative pregnancy rate via multiple fresh or frozen embryo transfers in women with current, resected, or recurred endometrioma

OBJECTIVE

This study aimed to retrospectively analyze the cumulative pregnancy rate (PR) via multiple fresh or frozen embryo transfers (ET) in women with current, resected, or recurred endometrioma.

MATERIALS AND METHODS

The IVF data including oocyte pick-up (OPU) and fresh or frozen ET in women with current (37 women; 56 OPU, 18 fresh and 14 frozen ET), resected (24 women; 50 OPU, 17 fresh and 42 frozen ET), or recurred endometrioma (28 women; 49 OPU, 22 fresh and 24 frozen ET) were obtained. All cycles were performed from 2015 to 2022 in a single university hospital.

RESULTS

The median serum AMH level (ng/mL) was 1.44, 1.47, and 0.98, respectively. The number of total or mature oocytes, fertilized oocytes, cleavage embryos at day-3, and top-quality embryos at day-3 were all similar in the three groups. Cycles with no oocyte occurred in 2 (3.6%), 1 (2%), and 3 cycles (6.1%), respectively. Freeze-all was performed in 46.3%, 59.2%, and 47.8% of the cycles, respectively (p > 0.05). The cumulative clinical PR per total ET (43.8%, 25.4%, and 21.7%), per OPU (25%, 30%, and 20.4%), and per woman (37.8%, 62.5%, and 35.7%) were all similar in the three groups. The cumulative ongoing pregnancy and live birth rate per total ET, per OPU, and per woman were also similar in the three groups.

CONCLUSION

Similarity in ovarian reserve, number of oocytes, number of embryos, cumulative clinical PR, and live birth in the three endometriosis groups indicates that the IVF outcomes in the 'recurrent endometrioma' group are not inferior to 'current' or 'resected' group.

Maternal Polycystic Ovary Syndrome and the Risk of Early Childhood Obesity in Female Offspring: A Nationwide Population-Based Study

BACKGROUND

To investigate the relationship between polycystic ovary syndrome (PCOS) in Korean women and childhood growth and obesity of their offspring.

METHODS

This longitudinal case-control study using the Korean National Health Insurance claims database and the National Health Screening Program for Infants and Children database included women who delivered singletons between January 2007 and December 2008. Offspring's body mass index (BMI) measurements taken between 42 and 80 months of age were compared according to a maternal history of PCOS.

RESULTS

Among a total of 131,805 participants, 1,213 women had a history of PCOS and 130,592 women did not. Female offspring aged 66-80 months born to women with PCOS had significantly higher BMI than those born to women without PCOS; there was no significant difference in that of male offspring regardless of maternal PCOS. In the generalized estimating equation and multivariable logistic regression analyses, the female offspring born to women with PCOS had a significantly higher risk of obesity during the age of 42-54 and 66-80 months (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.09-2.21 and OR, 1.5; 95% CI, 1.05-2.15, respectively), than those born to women without PCOS, after adjusting for several confounding factors.

CONCLUSION

Maternal PCOS is independently associated with an increased incidence of childhood obesity in female offspring among Korean women. Women with PCOS should consider the risk of early childhood obesity in their daughters, even if they maintain a healthy weight themselves.

Effects of time-restricted feeding on letrozole-induced mouse model of polycystic ovary syndrome

The present study aimed to investigate whether time-restricted feeding (TRF) ameliorates metabolic and reproductive phenotypes in a letrozole-induced mouse model of polycystic ovary syndrome (PCOS). Sixty female C57BL/6 N mice were randomly divided into two groups according to the type of food received: either a chow or a 60% high-fat diet. Those mice were subcutaneously implanted with letrozole or placebo pellets at four weeks of age. Then, letrozole-treated mice were randomly assigned to different feeding regimens: (1) TRF for 4 h (ZT12-ZT16) or (2) ad libitum diet. After 4 weeks of dietary intervention, estrous cycles were determined with daily vaginal smear examination, and serial tail-tip blood sampling was performed at 5-min intervals for 2 h to measure the luteinizing hormone (LH) pulse frequency, amplitude, and mean LH levels in the diestrus cycle stage. Letrozole-treated mice in the ad libitum group demonstrated multiple PCOS-like phenotypes including ovulatory dysfunction, polycystic ovaries, and increased body weight, parametrial fat weight, adipocyte size and inflammation, and higher expression of Cyp17, Cyp19, and Fshr in the ovary, and Kiss1r and Gnrh in the hypothalamus, elevated serum testosterone levels, and more rapid and elevated LH pulsatility, with increased pulse frequency, amplitude, and mean levels in the diestrus stage, compared with the controls. After TRF for 4 weeks, those phenotypes reverted to normal levels in letrozole-treated mice, except the percentage of diestrus cycles indicating the arrest of estrous cycling which did not differ between the TRF and ad libitum groups. Our results demonstrate that TRF has therapeutic effects on the reproductive and metabolic phenotypes of a letrozole-induced mouse model of PCOS.

Up-to-Date Knowledge on Osteoporosis Treatment Selection in Postmenopausal Women

The concept of a super-aged society has led to a steady increase in the average lifespan and hence, interest in a healthy life has increased. Aging is a major risk factor for many diseases, including osteoporosis. Osteoporotic fractures have a significant impact on the quality of life of the elderly and hence, it is pivotal to provide effective treatment of osteoporosis after menopause. Osteoporosis requires proper management and the treatment must be centered on long-term goals. New drugs with diverse mechanisms have been developed for treating osteoporosis. Current management of osteoporosis generally focuses on the importance of risk-based strategies to maximize the effectiveness of existing treatments and mitigate potential negative side-effects. Additionally, there is a need for sequential treatment of osteoporosis in the future. This review discusses the dynamic strategies for osteoporosis treatment and the importance of long-term management in postmenopausal women.

Age at Menopause and Suicidal Ideation in Menopausal Women: A Study of Korea National Health and Nutrition Examination Survey Data

BACKGROUND

Although menopause is considered a risk factor for depression, no association has been established between the risk of suicidal ideation and age at menopause. This study aimed to evaluate the association between age at menopause and suicidal ideation in middle-aged menopausal Korean women.

METHODS

This cross-sectional study used data from the Korea National Health and Nutrition Examination Survey (2013-2018). Women aged 40-65 years were divided into the following three categories: primary ovarian insufficiency (POI), early menopause, and menopause, according to age at natural menopause (< 40, 40-45, and > 45 years, respectively). Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9).

RESULTS

Among 2,232 menopausal women, 25 (1.1%) experienced POI and 114 (5.1%) experienced early menopause. The PHQ-9 items that pertained to low self-esteem and suicidal ideation scored higher in women with POI than in those who experienced menopause after 45 years of age. The prevalence of suicidal ideation differed significantly according to age at menopause (POI, 30.0%; early menopause, 12.7%; menopause, 8.0%; P = 0.016). Logistic regression analysis revealed that POI was significantly associated with suicidal ideation after the adjustment for age, body mass index, and education, household income, and walking levels (odds ratio, 4.2; 95% confidence interval, 1.0-17.7).

CONCLUSION

Korean middle-aged women with POI were more likely to have suicidal ideation than those who experienced menopause at 45 years or above, despite not being diagnosed with major depressive disorder.

Risk of Endometrial Polyps, Hyperplasia, Carcinoma, and Uterine Cancer After Tamoxifen Treatment in Premenopausal Women With Breast Cancer

IMPORTANCE

The association of tamoxifen use with the risk of uterine diseases, such as endometrial cancer, in premenopausal women with breast cancer remains controversial. However, many studies have reported an increased risk of uterine disease among postmenopausal tamoxifen users.

OBJECTIVE

To investigate the association of tamoxifen use with the risk of endometrial cancer and other uterine diseases in premenopausal women with breast cancer.

DESIGN, SETTING, AND PARTICIPANTS

A nationwide, population-based, retrospective longitudinal cohort study with an 18-year study period was conducted using data obtained from the Korean National Health Insurance Service. Participants included premenopausal women aged 20 to 50 years with breast cancer diagnoses between January 2003 and December 2018. Data were analyzed from April to December 2021.

EXPOSURES

Tamoxifen treatment.

MAIN OUTCOMES AND MEASURES

The incidence of uterine diseases, including endometrial cancer, hyperplasia, polyps, and other uterine cancers, was identified in the study cohort using insurance claim codes. The incidence of uterine diseases per 1000 person-years was compared between women receiving tamoxifen and those not treated with adjuvant hormone therapy. Multivariable Cox proportional hazard regression analysis was performed to determine the risk of each uterine disease.

RESULTS

Among 78 320 female participants with a mean (SD) age of 42.1 (6.1) years, 34 637 (44.2%) were categorized into the tamoxifen group and 43 683 (55.8%) were categorized into the control group. Among tamoxifen users, during the mean (SD) follow-up duration of 6.13 (4.15) years, the incidence of newly diagnosed endometrial polyps was 20.13 cases per 1000 person-years, that of endometrial hyperplasia was 13.49 cases per 1000 person-years, that of endometrial cancer was 2.01 cases per 1000 person-years, and that of other uterine cancers was 0.45 cases per 1000 person-years. The risk of endometrial cancer was higher in the tamoxifen group than in the control group (hazard ratio, 3.77; 95% CI, 3.04-4.66) after adjusting for age, body mass index, history of diabetes, hypertension, dyslipidemia, polycystic ovary syndrome, gonadotropin-releasing hormone agonist treatment, and trastuzumab treatment.

CONCLUSIONS AND RELEVANCE

In this longitudinal cohort study, premenopausal Korean women with breast cancer who received tamoxifen as adjuvant hormone therapy had a significantly increased risk of endometrial hyperplasia, polyps, carcinoma, and other uterine cancers compared with those who were not treated with adjuvant hormone therapy. These findings suggest that clinicians should consider the risk of uterine disease among tamoxifen users, including premenopausal women.

Metabolic Disorders in Menopause

Menopause is an aging process and an important time equivalent to one-third of a woman's lifetime. Menopause significantly increases the risk of cardiometabolic diseases, such as obesity, type 2 diabetes, cardiovascular diseases, non-alcoholic liver disease (NAFLD)/metabolic associated fatty liver disease (MFFLD), and metabolic syndrome (MetS). Women experience a variety of symptoms in the perimenopausal period, and these symptoms are distressing for most women. Many factors worsen a woman's menopausal experience, and controlling these factors may be a strategy to improve postmenopausal women's health. This review aimed to confirm the association between menopause and metabolic diseases (especially MetS), including pathophysiology, definition, prevalence, diagnosis, management, and prevention.

Correlation of oocyte number with serum anti-Müllerian hormone levels measured by either Access or Elecsys in fresh in vitro fertilization cycles

Objective

The aim of this study was to assess the correlation of oocyte number with serum anti-Müllerian hormone (AMH) levels measured by two automated methods (Access or Elecsys) in fresh stimulated in vitro fertilization (IVF) cycles.

Methods

In this retrospective study at a university hospital, data were collected from 243 fresh stimulated IVF cycles performed from August 2016 to December 2020. The serum AMH level was measured by Access in 120 cycles and by Elecsys in 123 cycles. The cut-off of serum AMH for prediction of poor responders (three or fewer oocytes) or high responders (15 or more oocytes) was calculated by the receiver operating characteristic curve analysis.

Results

For the two automated methods, the following equations were derived: total oocyte number=2.378+1.418×(Access-AMH) (r=0.645, p<0.001) and total oocyte number=2.417+2.163×(Elecsys-AMH) (r=0.686, p<0.001). The following combined equation could be derived: (Access-AMH)=0.028+1.525×(Elecsys-AMH). To predict poor responders, the cut-off of Access-AMH was 1.215 ng/mL (area under the curve [AUC], 0.807; 95% confidence interval [CI], 0.730–0.884; p<0.001), and the cut-off of Elecsys-AMH was 1.095 ng/mL (AUC, 0.848; 95% CI, 0.773–0.923; p<0.001). To predict high responders, the cut-off of Access-AMH was 3.450 ng/mL (AUC, 0.922; 95% CI, 0.862–0.981; p<0.001), and the cut-off of Elecsys-AMH was 2.500 ng/mL (AUC, 0.884; 95% CI, 0.778–0.991; p<0.001).

Conclusion

Both automated methods for serum AMH measurement showed a good correlation with oocyte number and good performance for predicting poor and high responders in fresh stimulated IVF cycles. The Access method usually yielded higher measured serum AMH levels than the Elecsys method.

Management of endometrial polyps in infertile women: A mini-review

Considerable disagreement exists regarding whether endometrial polyps should be removed before attempting natural pregnancy and before pregnancy via intrauterine insemination (IUI) or in vitro fertilization (IVF). Through a literature review, we obtained information on the impact of endometrial polyps and polypectomy on fertility outcomes. Several observational studies have suggested that women with unexplained infertility may benefit from endometrial polypectomy for a future natural pregnancy. A few studies reported benefits from endometrial polypectomy in infertile women who plan to undergo IUI. However, no strong evidence supports polypectomy as a way to improve the pregnancy rate in infertile women who plan to undergo IVF or polypectomy during controlled ovarian stimulation for IVF. Although no studies have defined criteria for the polyp size that should be removed in infertile women, clinicians should be aware that small endometrial polyps (<10 mm) sometimes regress spontaneously. Endometrial polypectomy is currently justified in patients with repeated IVF failure, but more studies are needed to verify that endometrial polypectomy itself will eventually increase the pregnancy rate. Although several mechanisms by which endometrial polyps exert a negative effect on fertility have emerged, there is no consensus about the proper management of endometrial polyps in infertile women. Therefore, the management of endometrial polyps should be individualized depending on the patient's situation and clinician’s preference.

Injection funnel persistence time and oolemma resistance during intracytoplasmic sperm injection and subsequent embryo development

OBJECTIVE

This study aimed to investigate whether the injection funnel persistence time and oolemma resistance during the intracytoplasmic sperm injection (ICSI) are associated with subsequent embryo quality.

DESIGN

A prospective observational study at a university hospital.

METHODS

One hundred and twenty normal-appearing metaphase II oocytes were collected from 54 ICSI cycles. Injection funnel was observed at 0, 30, 60, and 90 s after ICSI, and the injection funnel persistence time was assigned to "no funnel," "0-30," "30-60," "60-90," and ">90 s." The degree of oolemma resistance during ICSI was recorded as "no," "mild," "moderate," and "severe." Subsequent embryos on day 3 after ICSI were evaluated morphologically, and formation of top-quality embryo and embryo score was assessed. We newly developed "oolemma score," based on the injection funnel persistence time and oolemma resistance, and the predictability of top-quality embryo was assessed.

RESULTS

Among the five groups by injection funnel persistence time, the proportion of top-quality embryo and embryo score (64.3%, 32) was highest in the "30-60 s," but not significant. Among the four groups by oolemma resistance, the proportion of top-quality embryo and embryo score (53.7%, 32) was highest in "no group." The proportion of top-quality embryo in "no group" was significantly higher than "moderate group" (p = 0.012) and "severe group" (p = 0.043). The median embryo score in "no group" was significantly higher than "severe group" (p = 0.041). Newly developed "oolemma score" could predict well the formation of top-quality embryo with a statistical significance (cutoff >14.5, area under the curve 0.695, p < 0.001).

CONCLUSION

Embryo quality or score is more closely associated with oolemma resistance during ICSI. New "oolemma score" would help to identify embryo developmental potential of each mature oocyte in ICSI cycles.

The Largest Uterine Leiomyoma Removed by Robotic-Assisted Laparoscopy in the Late Reproductive Age: A Case Report

Uterine leiomyoma is a very common gynecological tumor in the reproductive years. Recent studies have shown that surgical treatment of uterine leiomyoma using robotic-assisted laparoscopic myomectomy (RALM) is associated with significantly fewer complications, lower estimated blood loss, fewer conversions, and less bleeding than conventional laparoscopic myomectomy. This study reports the case of a giant uterine leiomyoma treated using RALM. A 50-year-old woman was referred to our outpatient clinic with progressive abdominal distension. Ultrasonography and magnetic resonance imaging were performed and showed a markedly enlarged uterus containing a 28-cm uterine myoma. RALM confirmed the 28-cm subserosal myoma on the posterior wall of the uterus. The myoma was enucleated, and the myometrial and serosal defect was repaired with a continuous suture using barbed suture materials. The entire myoma was removed using an electric morcellator. The operation lasted for 190 minutes. The total weight of the removed myoma was 3,262 g, and uterine leiomyoma was pathologically diagnosed. There were no postoperative complications. Although the treatment of huge myomas using RALM is controversial and technically demanding, we successfully performed RALM in a patient with a large myoma. This case confirms the efficiency, reliability, and safety of a robotic-assisted laparoscopic approach for removing a huge myoma. In a well-selected case, RALM can be performed by experienced surgeons regardless of the size of fibroids.

Berberine reduce allergic inflammation in a house dust mite allergic rhinitis mouse model

BACKGROUND

Berberine (Ber), used widely as an antibacterial, antifungal, and anti-inflammatory drug, has long been used as a gastrointestinal remedy in Chinese traditional medicine. Recent reports have suggested that Ber suppresses Th17 responses that was mediated by direct actions on T cells and thymic stromal lymphopoietin production in primary mast cells. It has been suggested that Ber may be useful in treating allergic response. The purpose of this study was to assess the effects of Ber treatment on allergic inflammation in an allergic rhinitis mouse model and to examine the underlying mechanism(s).

METHODS

BALB/c mice were divided into control, Derf with no treated (Derf), Ber treated, and Ber with anti-C25 monoclonal antibody treated (Ber + anti-CD25) groups. All mice, with the exception of the control group, were sensitized with an intraperitoneal i.p. injection of Dermatophagoides farinae (Derf). Mice in the Ber and Ber + anti-CD25 group were treated intranasally with 10 #181;g/mL. Then, 1 week after sensitization, all mice were challenged intranasally with 20 #181;g Derf for 5 consecutive days. Mice in the anti-CD25 group were treated intraperitoneally with 250 #181;g anti-CD25 monoclonal antibody 1 day before the first intra-nasal challenge with Derf. Allergic symptom scores, eosinophil counts, and serum Derf-specific IgE levels were measured. T-bet, GATA-3, interferon-g (IFN-γ), interleukin (IL)-10, IL-13, and Foxp3 expression was examined by real-time polymerase chain reaction and Western blotting. CD4⁺ CD25⁺ Foxp3⁺ T cells were assessed by flow cytometry.

RESULTS

Symptom scores, serum Derf-specific IgE levels, GATA-3 mRNA levels, T-bet mRNA levels, and tissue eosinophil counts were decreased in the Ber versus the Derf group. In the Ber + anti-CD25 group, serum IL-10 levels were decreased versus the control, Derf, and Ber groups. In the Ber + anti-CD25 mAb groups, Foxp3 mRNA levels were decreased versus the control group. In the Ber group, Foxp3 mRNA levels were increased versus the control group. In the Ber group, the percentage of CD4⁺ CD25⁺ Foxp3⁺ T cells was increased versus the Derf group. The percentage of CD4⁺ CD25⁺ Foxp3+ T cells was increased in the Ber versus the Derf groups.

CONCLUSIONS

In our study, Ber reduced allergic inflammation significantly. Moreover, our findings suggest that the mechanism of action of Ber may be via CD4⁺ CD25⁺ Foxp3⁺ Treg cells, possibly through not only by increasing their numbers but also altering their function.

Mechanical properties and microstructure of AZ31 Mg alloy containing Ca element fabricated by various rolling speeds

It was reported that the yield strength (YS) of a rolled Mg-3 wt%, Al-1 wt%, Zn-0.3 wt%, Ca alloy reached 340 MPa. The YS value of a rolled Mg-Al-Zn alloy decreases with increasing the rolling speed but that of a rolled Mg-Al-Zn-Ca alloy remains unchanged until the rolling speed of 5 m/min. Static recrystallization behavior in Mg-Al-Zn alloy occurred as a function of rolling speeds; on the other hand, it did not happen in Mg-Al-Zn-Ca alloy. A number of fine precipitates were observed in the grain of the latter alloy, suggesting that they restrain the dislocations from moving during rolling processes and keep the high strength. From the result of boss-forming test, the Mg-Al-Zn-Ca alloy shows more boss-formability than Mg-Al-Zn alloy.

Identification of glutathione conjugates and mercapturic acids of 1,2-dibromopropane in female BALB/c mice by liquid chromatography-electrospray ionization tandem mass spectrometry

Based on recent results that 1,2-dibromopropane (1,2-DBP) causes hepatotoxicity and immunotoxicity in female BALB/c mice as well as a reduction of hepatic glutathione levels, the possible formation of glutathione conjugates and mercapturic acids of 1,2-DBP was investigated in vivo in the present studies. The following four metabolites were identified in the liver at 12 h after treatment with 1,2-DBP, by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS): M1, 2-hydroxypropylglutathione; M2, 2-oxopropylglutathione; M3, N-acetyl-S-(2-hydroxypropyl)-L-cysteine; and M4, N-acetyl-S-(2-oxopropyl)-L-cysteine. Ions of individual conjugates were observed at m/z 366, 364, 222 and 220, respectively. Characteristic product ions at m/z 237, 217, 204 and 202 for the identification of M1, M2, M3 and M4 were observed, respectively. In the sera isolated from the same animals, only mercapturic acids (M3 and M4) were observed by LC-ESI/MS. When female BALB/c mice were treated orally with 1,2-DBP at doses of 150, 300 and 600 mg kg(-1) once for 12 h, the production of glutathione conjugates and mercapturic acids in liver was apparently dose dependent, as were the concentrations of them in sera. When the production of metabolites from 1,2-DBP was investigated in liver following oral treatment with 600 mg kg(-1) 1,2-DBP for 6, 12, 24 and 48 h, metabolite concentrations were greatest at the first time point (6 h). The results explain the authors' previous studies that oral treatment with 1,2-DBP reduces the hepatic content of glutathione.

Hepatoprotective effects of Platycodon grandiflorum on acetaminophen-induced liver damage in mice

The protective effects of an aqueous extract from the roots of Platycodon grandiflorum A. DC (Campanulaceae), Changkil (CK), on acetaminophen (APAP)-induced hepatotoxicities and the possible protective mechanisms involved were investigated in mice. Pretreatment with CK prior to the administration of APAP significantly prevented the increase in serum alanine aminotransferase and aspartate aminotransferase activity and hepatic lipid peroxidation in a dose-dependent manner. APAP-induced hepatotoxicity was also essentially prevented as evidenced by liver histopathology. Hepatic glutathione levels and glutathione-S-transferase activities were not affected by treatment with CK alone, but pretreatment with CK protected the APAP-induced depletion of hepatic glutathione levels. The effects of CK on cytochrome P450 (P450) 1A2 and 2E1, the major isozymes involved in APAP bioactivation, were investigated. In microsomal incubations, CK effectively inhibited P450 lA2-dependent methoxyresorufin O-deethylase activities and the P450 2E1-dependent p-nitrophenol and aniline hydroxylase. The results suggest that the protective effects of CK against the APAP-induced hepatotoxicity may, at least in part, be due to its ability to block P450-mediated APAP bioactivation.

Ursolic acid enhances nitric oxide and tumor necrosis factor-alpha production via nuclear factor-kappaB activation in the resting macrophages

Ursolic acid (UA), a pentacyclic triterpene acid, is reported to have anti-tumor activities; however, the mechanism underlying its anti-tumorigenic effects is poorly understood. To further determine the mechanism of UA, we investigated the effects of UA on the release of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha), and on the level of inducible nitric oxide synthase (iNOS) and TNF-alpha gene expression in mouse resting macrophages. We found that UA elicited a dose-dependent increase in NO and TNF-alpha production, and the level of iNOS and TNF-alpha mRNA. Transient expression and electrophoretic mobility shift assays with nuclear factor-kappaB (NF-kappaB) binding sites revealed that the increased level of iNOS mRNA and TNF-alpha mRNA induced by UA were mediated by the NF-kappaB transcription factor complex. These results demonstrate that UA stimulates NO and TNF-alpha release and is able to upregulate iNOS and TNF-alpha expression through NF-kappaB transactivation in the resting macrophages.

Nitric oxide and tumor necrosis factor-alpha production by oleanolic acid via nuclear factor-kappaB activation in macrophages

Oleanolic acid (OA), a pentacyclic triterpene acid, is reported to have antitumor activities; however, the mechanism underlying its antitumorigenic effects is poorly understood. To further determine the mechanism of OA, we investigated the effects of OA on the release of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) and on the level of inducible nitric oxide synthase (iNOS) and TNF-alpha gene expression in mouse macrophages. We found that OA elicited a dose-dependent increase in NO and TNF-alpha production. Reverse transcription-polymerase chain reaction showed that the increased NO and TNF-alpha secretion were due to an increase in iNOS mRNA and TNF-alpha mRNA, respectively. Since iNOS and TNF-alpha transcription have recently been shown to be under the control of the NF-kappaB transcription factor, the effects of OA on NF-kappaB activation were examined using a transient transfection assay and an electrophoretic mobility shift assay (EMSA). Transient expression assays with NF-kappaB binding sites linked to the luciferase gene revealed that the increased levels of iNOS mRNA and TNF-alpha mRNA induced by OA were mediated by the NF-kappaB transcription factor complex. Using DNA fragments containing the NF-kappaB binding sequence, OA was shown to activate the protein/DNA binding of NF-kappaB to its cognate site as measured by EMSA. These results demonstrate that OA stimulates NO and TNF-alpha release and is able to upregulate iNOS and TNF-alpha expression through NF-kappaB transactivation, which may be the mechanism whereby OA elicits its biological effects.

Aqueous extract isolated from Platycodon grandiflorum elicits the release of nitric oxide and tumor necrosis factor-alpha from murine macrophages

Herbal medicines are increasingly being utilized to treat a wide variety of disease processes. Aqueous extract from the root of Platycodon grandiflorum A. DC (Campanulaceae), Changkil (CK), is reported to have antitumor and immunomodulatory activities; however, the mechanism underlying its therapeutic effect is not known. In the present study we examined the effects of CK on the release of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha), and on the gene expression of iNOS and TNF-alpha in mouse macrophages. CK elicited a dose-dependent increase in NO and TNF-alpha production in cultured macrophages. CK significantly affected secretion at concentrations of more than 5 micrograms/ml, and its maximum effect was at concentration of 100 micrograms/ml. Reverse transcription polymerase chain reaction showed that increases in NO and TNF-alpha secretion were due to an increase in inducible NO synthase mRNA and TNF-alpha mRNA, respectively. Transient expression assays with NF-kappa B binding sites linked to the luciferase gene revealed that CK-induced increase of inducible NO synthase mRNA and TNF-alpha mRNA were mediated by the NF-kappa B transcription factor complex. These results demonstrate that CK stimulates NO and TNF-alpha release and is able to upregulate iNOS and TNF-alpha expression through NF-kappa B transactivation and this may be a mechanism whereby this herbal medicine elicits its therapeutic effects.

Augmentation of macrophage functions by an aqueous extract isolated from Platycodon grandiflorum

Platycodon grandiflorum has been claimed to have a wide range of health benefits, which include immunostimulation and antitumor activity. The associated biological mechanisms are unclear; however, of the wide diversity of effects, it is believed that their activities may be exerted through several potent effector cells such as macrophages. Therefore, the effects of an aqueous extract from the root of P. grandiflorum (Changkil: CK) on mouse peritoneal macrophage function were investigated. It was found that CK stimulated macrophage proliferation, spreading ability, phagocytosis, cytostatic activity, and nitric oxide production in a dose-dependent manner, and that the production of cytokines such as TNF-alpha, IL-1beta and IL-6 were similarly increased. CK significantly affected secretion at concentrations greater than 10 microg/ml; its maximal effects were at the concentration of 100 microg/ml. Reverse transcription-polymerase chain reaction showed that CK increased the appropriate cytokine mRNAs. These results suggest that CK is a potent enhancer of macrophage function.

Suppression of CYP1A1 expression by 4-nonylphenol in murine Hepa-1c1c7 cells

This study investigated the effects that 4-nonylphenol (NP) has on CYP1A1 expression in Hepa-1c1c7 cell cultures. NP alone did not affect CYP1A1-specific 7-ethoxyresorufin-O-deethylase (EROD) activity. In contrast, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible EROD activities were markedly reduced upon concomitant treatment with TCDD and NP in a dose-dependent manner. Treatment with tamoxifen, an anti-estrogen that acts through the estrogen receptor, did not affect the suppressive effects that NP has on TCDD-inducible EROD activity. The TCDD-inducible CYP1A1 mRNA levels were markedly suppressed upon concomitant treatment with TCDD and NP that is consistent with their effects on EROD activity. A transient transfection assay using dioxin-response element (DRE)-linked luciferase and an electrophoretic mobility shift assay revealed that NP reduced the transformation of the aryl hydrocarbon (Ah) receptor to a form capable of binding specifically to the DRE sequence of the CYP1A1 gene promoter. These results suggest that the down-regulation of CYP1A1 gene expression by NP in Hepa-1c1c7 cells might be an antagonism of the DRE-binding potential of the nuclear Ah receptor, but is not mediated through the estradiol receptor.

Cytokine-mediated suppression of cytochrome P450 1A1 in Hepa-1c1c7 cells by pokeweed mitogen

This study investigated the effects of pokeweed mitogen (PWM) on the regulation of cytochrome P450 (P450) 1A1 expression in an in vitro model, using murine hepatoma cell line Hepa-1c1c7 and murine macrophage cell line RAW 264.7 cell cultures. PWM added directly to Hepa-1c1c7 cells had no effect on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced P450 1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity. However, TCDD-induced EROD activity and P450 1A1 mRNA levels were markedly suppressed when Hepa-1c1c7 cells were cultured with PWM-treated conditioned media from RAW 264.7 in a dose-dependent manner. Concomitant treatment with PWM and pentoxifylline, a TNFalpha synthesis inhibitor, to RAW 264.7 cells decreased the suppressive effects of PWM on TCDD-induced EROD activity. In PWM-exposed RAW 264.7 cell cultures, TNFalpha and IL-6 levels increased in a dose-dependent fashion. When antibodies to TNFalpha or/and IL-6 were added to PWM-treated conditioned media from RAW 264.7, the suppression of EROD activity was inhibited. These results suggested the suppression of P450 1A1 by PWM was mediated exclusively by TNFalpha and IL-6, released from macrophages.

Down-regulation of murine Cyp1a-1 in mouse hepatoma Hepa-1c1c7 cells by bisphenol A

Cultured mouse hepatoma Hepa-1c1c7 cells were treated with either bisphenol A or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or in combination to assess the role of bisphenol A in the process of Cyp1a-1 induction. Treatment of Hepa-1c1c7 cultures with 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) induced Cyp1a-1, as determined by analysis of 7-ethoxyresorufin O-deethylase (EROD) activities. Bisphenol A alone did not affect the activity of Cyp1a-1-specific EROD; in contrast, TCDD-induced EROD activities were markedly reduced in the concomitant treatment of TCDD and bisphenol A in a dose-dependent manner. Treatment with tamoxifen, an antiestrogen that acts through the estrogen receptor, did not affect the suppressive effects of bisphenol A on TCDD-induced EROD activity. TCDD-induced Cyp1a-1 mRNA levels were markedly suppressed in the concomitant treatment of TCDD and bisphenol A consistent with their effects on EROD activity. Transient transfection assay using dioxin-response element (DRE)-linked luciferase revealed that bisphenol A reduced transformation of the aryl hydrocarbons (Ah) receptor to a form capable of specifically binding to the DRE sequence in the promoter of the Cyp1a-1 gene. These results suggest the down-regulation of the Cyp1a-1 gene expression by bisphenol A in Hepa-1c1c7 cells might be antagonism of the DRE binding potential of nuclear Ah receptor but not mediated through estradiol receptor.

Suppression of IL-2 and IL-4 gene expression by nodularin through the reduced NF-AT binding activity

Nodularin is a cyclic peptide produced by cyanobacteria. In the present study, the inhibitory effect of nodularin on T lymphocyte functions was demonstrated. Direct addition of nodularin to B6C3F1 mouse splenocyte cultures produced a concentration-dependent inhibition of the lymphoproliferative response to concanavalin A stimulation. Nodularin inhibited PMA plus ionomycin (Io)-induced IL-2 mRNA expression in murine splenocytes and thymocytes as determined by quantitative/competitive RT-PCR. To further characterize the mechanism for the transcriptional regulation of IL-2, the binding activity of transcription factors, NF-AT, AP-1, NF-kappaB, and Oct, was evaluated by electrophoretic mobility shift assays in mouse splenocytes. Nodularin reduced the NF-AT binding activity in PMA/Io-induced splenocytes, but no significant effect was observed on AP-1, NF-kappaB, or Oct binding activity. Nodularin also inhibited IL-4 mRNA expression in PMA/Io-stimulated murine splenocytes. These results suggest that T lymphocyte is a possible cellular target of nodularin, and the inhibitory effect of nodularin on T-cell specific transcription factor NF-AT induces T-cell dysfunction, which leads to a diminution in IL-2 and IL-4 gene transcription.

Isolation and characterization of a mutant defective in the production of methanol dehydrogenase from a new restricted facultative methanol-oxidizing bacterium

A new restricted facultative methanol-oxidizing bacterium Methylobacillus sp. strain SK1 (DSM 8269) was subjected to insertion mutagenesis studies with the transposon Tn5 to generate mutants deficient in the production of methanol dehydrogenase (MDH). The transposon was conjugally transferred into the methylotroph by using the triparental mating procedure. The mutants induced by Tn5 were selected directly from a plate containing succinate by using the allyl alcohol selection procedure. The transposition of Tn5 to the bacterium showed a moderate transposition frequency (10(-5) - 10(-6)). Southern hybridization analysis confirmed that the transposon Tn5 was inserted into the chromosomal DNA of the mutants. In addition, the mutants had no RNA transcripts produced from the mdh gene, as judged by Northern blot analysis. The mutants could neither grow on methanol nor produce MDH protein, as determined by Western blot analysis with anti-MDH antibody. These results suggest that Tn5 mutagenesis maybe a useful tool for the molecular analysis of a facultative methanol-oxidizing bacterium.

Suppressive effects of alpha-Hederin on 2,3,7,8-tetrachlorodibenzo-p-dioxin-mediated murine Cyp1a-1 expression in the mouse hepatoma Hepa-1c1c7 cells

Cultured mouse hepatoma cell line Hepa-1c1c7 cells were treated with alpha-Hederin to assess the role of alpha-Hederin in the process of Cyp1a-1 induction. Treatment of Hepa-1c1c7 cultures with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced Cyp1a-1, as indicated by analysis of 7-ethoxyresorufin O-deethylation (EROD) activity and Cyp1a-1 protein. When alpha-Hederin and TCDD were both added to cultures, TCDD-inducible EROD activity was greatly suppressed by alpha-Hederin in a dose-dependent manner. TCDD-induced Cyp1a-1 protein and mRNA levels were markedly reduced in the concomitant treatment of TCDD and alpha-Hederin consistent with EROD activity. Electrophoretic mobility shift assay using nuclear extraction of cells revealed that alpha-Hederin reduced transformation of the Ah receptor to a form capable of specifically binding to an oligonucleotide containing a dioxin-response element (DRE) sequence of the Cyp1a-1 gene. These results suggest that the suppressive effect of alpha-Hederin on TCDD-induced Cyp1a-1 gene expression in Hepa-1c1c7 cells might be an antagonist of the DNA binding potential of a nuclear Ah receptor.

Inhibition of cytochrome P450 2E1 expression by oleanolic acid: hepatoprotective effects against carbon tetrachloride-induced hepatic injury

The protective effects of oleanolic acid on carbon tetrachloride-induced hepatotoxicities and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with oleanolic acid prior to the administration of carbon tetrachloride significantly prevented the increase in serum alanine aminotransferase and lactate dehydrogenase activity and liver lipid peroxidation in a dose-dependent manner. Hepatic glutathione levels and glutathione-S-transferase activities were not affected by treatment with oleanolic acid alone but pretreatment with oleanolic acid protects carbon tetrachloride-induced depletion of hepatic glutathione levels. The effects of oleanolic acid on the cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation were investigated. Treatment of mice with oleanolic acid resulted in a significant decrease of P450 2E1-dependent p-nitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. These results show that the protective effects of oleanolic acid against the carbon tetrachloride-induced hepatotoxicity may, at least in part, be due to its ability to block bioactivation of carbon tetrachloride mainly by the inhibition of expression and activities of P450 2E1.

Induction of inducible nitric oxide synthase gene expression by Pokeweed mitogen

The present study has characterized the expression of iNOS gene in Pokeweed mitogen (PWM)-driven murine macrophage RAW 264.7 cells. PWM significantly induced nitric oxide production in a dose-dependent manner. Quantitative reverse transcription-polymerase chain reaction analysis demonstrated that the inducible nitric oxide synthase gene expression is increased by PWM treatment. Since iNOS transcription has recently been shown to be under the control of the nuclear factor (NF)-kappaB/Rel family of transcription factors, the effects of PWM on NF-kappaB/Rel activation were examined using a transient transfection assay and an electrophoretic mobility shift assay (EMSA). Transient expression assays with NF-kappaB/Rel binding sites linked to the chloramphenicol acetyltransferase gene suggest that the PWM-induced increase in transcription is mediated by the NF-kappaB/Rel transcription factor complex. Using DNA fragments containing the NF-kappaB/Rel binding sequence, PWM was shown to activate the protein/DNA binding of NF-KB/Rel to its cognate site as measured by EMSA. Supershift EMSA showed the presence of p50 and c-Rel protein in the complex at the kappaB site. Western blot analysis of isolated nuclear fractions, using p65 and c-Rel-specific antibodies, provided further evidence that c-Rel is increased by PWM treatment. N-Tosyl-1-phenylalanine chloromethyl ketone, a potent inhibitor of NF-kappaB/Rel activation, inhibited PWM-induced nitrite generation in a dose-dependent manner. Collectively, the results of these experiments indicate that c-Rel is positively regulated by PWM to assist in the initiation of iNOS gene expression.

Differential effects of B- and T-lymphocyte mitogens on cytochrome P450 in mice

Lipopolysaccharide (LPS) is widely used as a B-lymphocyte mitogen and is known to depress expression of the cytochrome P450 (P450). However, there have been no studies regarding to the effects of the other mitogens on the expression of P450. This study investigated the effects of mitogens on the constitutive and inducible expression of mouse hepatic P450. Following treatment with B-lymphocyte mitogens, such as LPS and pokeweed mitogen (PWM), hepatic P450 content was reduced. LPS and PWM also suppressed activities of microsomal ethoxyresorufin O-deethylase, pentoxyresorufin O-dealkylase and aniline hydroxylase, a representative activity of P4501A1/2, P4502B1/2 and P4502E1, respectively, in both constitutive and P450 induced mice. However, there was no effect when treated with T-lymphocyte mitogens, such as concanavalin A and phytohemagglutinin. Suppression of P450 expression in the LPS- or PWM-treated mice occurred and was shown to involve a decrease in P450 protein and mRNA levels in liver. These results suggest that suppressive effects of mitogens on the expression of P450 might be different and that B-lymphocyte mitogens selectively depress the expression of P450.

Protective effects of diallyl sulfide on N-nitrosodimethylamine-induced immunosuppression in mice

Diallyl sulfide (DAS), a flavor component of garlic that has been used as a food additive, exerts chemopreventive effects at several organ sites in rodents after administration of chemical carcinogens possibly by inhibiting carcinogen activation via cytochrome P450-mediated oxidative metabolism. In this study, we investigated the protective effect of DAS on the N-nitrosodimethylamine (NDMA)-induced immunosuppression of humoral and cellular responses in BALB/c mice and the possible mechanisms involved in this protection. We observed that oral administration of DAS prior to NDMA treatment for 14 consecutive days blocked the NDMA-induced suppression of the antibody response to a T-cell-dependent antigen, sheep erythrocytes, and the lymphoproliferative response to the T-cell and the B-cell mitogens in dose-dependent manners. Treatment of mice with DAS resulted in a significant decrease of cytochrome P450 2E1-dependent p-nitrophenol hydroxylase and NDMA demethylase activities. The results show that the protective effects of DAS against the NDMA-induced immunotoxicity may, at least in part, be due to its ability to block bioactivation of NDMA mainly by the inhibition of cytochrome P450 2E1.

Suppression of constitutive and inducible cytochrome P450 gene expression by alpha-hederin in mice

The effects of alpha-Hederin, a triterpenoid saponin which exists in some oriental herbs, on the expression of liver cytochrome P450s were examined in mice. The administration of alpha-Hederin to mice significantly decreased the hepatic content of P450 and the activities of microsomal ethoxyresorufin O-deethylase, methoxyresorufin O-demethylase, and aniline hydroxylase, representative activities of cytochrome-P4501A1, -P4501A2, and -P4502E1, respectively, in a dose- and time-dependent manner. However, pentoxyresorufin O-dealkylase, a representative activity of cytochrome P4502B1/2, was decreased to a lesser extent. alpha-Hederin also decreased inducible monooxygenase activities in the same manner. Suppressions of P450 isozyme expression occurred in alpha-Hederin treated hepatic microsomes, as determined by immunoblot analysis in a manner consistent with that of the enzyme activity levels. Levels of mRNA of P4501A1/2 and P4502B1/2 were also decreased by alpha-Hederin as shown by Northern blot analysis. In contrast, the level of P4502E1 mRNA in the liver of alpha-Hederin treated mice was unchanged. These results suggest that alpha-Hederin may act as a more specific suppressor for P4501A and P4502E1 than P4502B and that the suppression involves decreases in mRNA levels except in the case of P4502E1.

Suppressive effects of estradiol on 2,3,7,8-tetrachlorodibenzo-p-dioxin-mediated transcriptional activation of murine Cyp1a-1 in mouse hepatoma Hepa 1c1c7 cells

Cultured mouse hepatoma Hepa lclc7 cells were treated with either estradiol or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or in combination to assess the role of estradiol in the process of Cypla-1 induction. Estradiol at a concentration as high as 1 microM slightly increased the activity of Cypla-1-specific 7-ethoxyresorufin O-deethylase (EROD); in contrast, TCDD-induced EROD activity and Cypla-1 mRNA levels were markedly reduced in the concomitant treatment of TCDD and estradiol in a dose-dependent manner. Treatment with tamoxifen, an anti-estrogen which acts through the estrogen receptor, did not affect the suppressive effects of estradiol on TCDD-induced EROD activity. Electrophoretic mobility shift assay using nuclear extract of cells revealed that estradiol reduced transformation of the Ah receptor to the form capable of specifically binding to an oligonucleotide containing dioxin-response element (DRE) sequence. Consistent with this, estradiol decreased TCDD-induced increased chloramphenicol acetyltransferase (CAT) activity from a DRE-containing CAT reporter plasmid after transient transfection into the cells. The levels of the cytosolic [3H]TCDD-Ah receptor complex were reduced by estradiol in competitive Ah receptor binding assay using [3H]TCDD. This study demonstrated that estradiol acts as an antagonist to TCDD and can regulate Cyp1a-1 expression in an Ah receptor-dependent manner but not through estradiol receptor in Hepa 1c1c7 cells.

Effects of estradiol and progesterone on cytochrome P4501A1 expression in Hepa 1c1c7 cells

The effects of estradiol and progesterone on the expression of cytochrome P4501A1 were investigated in Hepa 1c1c7 cells. Both steroids, at 10 microM concentration, increased P4501A1-mediated 7-ethoxyresorufin O-deethyalase activity and amounts of its immunoreactive protein and CYP1A1 mRNA. Gel shift assay revealed that the steroids could induce both AhR transformation and binding of the ligand-AhR complex to its specific DNA recognition site. Transient transfection demonstrated that 5'flanking region of CYP1A1 could respond to the steroid action. The competitive binding assay showed that the steroids bound to AhR with moderate affinity. These results suggested that steroidal structure can be AhR ligands and induce CYP1A1 expression in AhR-dependent manner.

The prevention of carbon tetrachloride-induced hepatotoxicity in mice by alpha-hederin: inhibiton of cytochrome P450 2E1 expression

The protective effects of alpha-Hederin on carbon tetrachloride-induced hepatotoxicities were investigated in mice. Pretreatment with alpha-Hederin prior to the administration of carbon tetrachloride significantly prevented the increase in serum alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) activity and lipid peroxidation in a dose dependent manner. Hepatic glutathione levels and glutathione-S-transferase activities were not affected by pretreatment with alpha-Hederin alone but pretreatment with alpha-Hederin protects carbon tetrachloride-induced depletion of hepatic glutathione levels. The effects of alpha-Hederin on the cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation were investigated. alpha-Hederin markedly decreased the P450 2E1-specific activities of p-nitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. These results demonstrate that treatment of mice with alpha-Hederin decreases the expression and activities of P450 2E1 enzyme, and reduces biotransformation of carbon tetrachloride, and diminished carbon tetrachloride-induced liver injury.

Characterization of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in B6C3F1 and DBA/2 mice following single and repeated exposures

Previous studies have demonstrated that repeated (14 day) administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) enhances the suppression of humoral immunity in DBA/2 (Ah-low responder) mice relative to the effect seen with identical cumulative doses after a single treatment (cumulative doses of 4.2, 14.0, and 42 mg/kg). In the present studies, we have explored this phenomenon further by determining the status of several specific parameters, which might account for the increase in antibody suppression in the DBA/2 strain following repeated TCDD exposures. Included in these studies was the induction of hepatic and splenic microsomal 7-ethoxyresorufin-o-deethylase (EROD; P4501A1) activity and biodistribution of the administered TCDD into various target organs and tissues. Changes in lymphocyte subpopulations within the spleen were also assessed by flow cytometry following both single and repeated dosing. All studies made use of direct comparisons between DBA/2 (Ah-low responder) and B6C3F1 (Ah-high responder) female mice. Results of these studies demonstrate that the enhanced suppression of humoral immunity in DBA/2 mice following repeated exposure to TCDD is not directly associated with increases in liver microsomal EROD activity and does not appear to be correlated with changes in the pattern of biodistribution or amount of TCDD within the liver or spleen of these animals. In contrast, the most significant changes that occurred following repeated dosing in either strain were observed in the levels of microsomal EROD activity and immune cell ratios within the spleen. This effect was characterized as an increase in microsomal EROD activity, and a corresponding reduction in the numbers of a non-B/non-T cell population in the spleen.

Murine Cyp1a-1 induction in mouse hepatoma Hepa-1C1C7 cells by myristicin

Mouse hepatoma Hepa-1c1c7 (Hepa-1) cells were treated with myristicin to assess the role of myristicin in the process of Cyp1a-1 induction. Treatment of Hepa-1 cells with myristicin increased Cyp1a-1 transcription in a dose-dependent manner as shown by analysis of 7-ethoxyresorufin O-deethylase activity, Cyp1a-1 protein level, and Cyp1a-1 mRNA. Myristicin, however, did not competitively displace [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin from the Hepa-1 cytosolic aryl hydrocarbon (Ah) receptor in a competitive Ah receptor binding analysis using sucrose density gradient sedimentation and did not affect formation of DNA-protein complexes between the Ah receptor and its DRE target in a gel mobility shift assay using oligonucleotides corresponding to DRE 3 of the Cyp1a-1. These results suggest that the induction of Cyp1a-1 gene expression by myristicin in Hepa-1 cells might occur through an Ah receptor-independent pathway.

Expression of 2,3,7,8-tetrachlorodibenzo-p-dioxin-inducible cytochrome P4501A1 in human splenic lymphocyte cultures

The induction of cytochrome P4501A1 (P4501A1) and P4501A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was investigated in human splenic lymphocytes cultures. EROD activity was induced by TCDD in mitogen (phytohemagglutinin and pokeweed mitogen) stimulated blast cells but not in the resting cells. TCDD markedly induced EROD activity in a dose- and time-dependent manner. The expression of P4501A1 mRNA was increased by TCDD in mitogen-stimulated cells as detected by Northern blot analysis. These findings support the conclusion that TCDD induced the expression of P4501A1 gene, resulting in increased EROD activity in mitogen-stimulated human splenic lymphocytes cultures.

Induction of rat hepatic cytochrome P450 enzymes by myristicin

The effect of myristicin on the expression of liver cytochrome P450s and its mRNA levels was examined in rats. Treatment of rats with myristicin (i.p., 500 mumol/kg) caused 2-20 fold increases in liver P450 1A1/2, 2B1/2, and 2E1 enzyme activities relative to controls. Immunoblot analysis using anti-rat liver P450 1A, 2B, and 2E1 showed that the increases in each of P450 protein levels by myristicin were consistent with those in enzyme activity levels. When increased levels of P450 mRNA by myristicin were examined by Northern blot analysis, levels of mRNA of P450 1A1/2 and 2B1/2 also increased. However, the level of P4502E1 mRNA did not increase. The total amount of spectrally detectable P450, also increased about 1.5-fold following treatment of myristicin. These results demonstrate that myristicin is an inducer of rat liver P450 1A1/2, 2B1/2, and 2E1, and that the induction involves increases in mRNA levels except in the case of P4502E1.

Non-specific inhibition of cytochrome P450 activities by chlorophyllin in human and rat liver microsomes

Chlorophyllin, a copper/sodium salt of chlorophyll used in the treatment of geriatric patients, inhibits the mutagenicity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 3-amino-1-methyl-5H- pyrido[4,3-b]indole (Trp-P-2), aflatoxin B1 and benzo[a]pyrene (B[a]P). Recent in vitro and in vivo studies have shown that a molecular complex is formed between IQ and chlorophyllin, suggesting that this complex formation might be responsible for the antigenotoxic effect of chlorophyllin observed. Cytochrome P450 (P450) enzymes appear to be the major catalysts in the bioactivation of these carcinogens. We have investigated the in vitro effects of chlorophyllin on several P450 activities including ethoxyresorufin O-deethylation, benzyloxyresorufin O-debenzylation, coumarin 7-hydroxylation, 7-ethoxycourmarin O-deethylation, B[a]P 3-hydroxylation, and chlorzoxazone 6-hydroxylation. Chlorophyllin non-specifically inhibited all of P450 activities observed. Spectrally detectable P450 was also destroyed in microsomes and purified P450 in a reconstituted system in the presence of chlorophyllin and an NADPH-generating system. These results suggest that the antigenotoxic effect of chlorophyllin might be due to inhibition of P450 enzymes involving bioactivation of carcinogens in addition to molecular complex formation between carcinogens and chlorophyllin. Comparison of the apparent Ki for P450 inactivation with previously estimated constants for chlorophyllin-IQ complexation suggest that P450 inhibition should be the dominant mechanism of inhibition.

Suppressed proliferation of mouse hepatoma cells by conditioned media from interferon gamma-treated hepatocytes

The effect of mouse interferon gamma (IFNg) on the proliferation of Hepa-1c1c7, mouse hepatoma cells was analyzed by means of [3H]thymidine incorporation. IFNg did not suppress the proliferation of Hepa-1c1c7 cells cultivated alone, however, it effectively suppressed in coculture with B6C3F1 mouse hepatocytes and in IFNg-treated mouse hepatocyte-conditioned media. Suppression of proliferation of hepatoma cells was detected only in the IFNg-treated hepatocyte-conditioned media but not in the control hepatocyte-conditioned media. The magnitude of suppression depended upon the amount of IFNg used in the preparation of conditioned media. The suppressive effect of IFNg-treated hepatocyte-conditioned media was retained by an ultrafilteration membrane (M.W. cut off 30,000), and its activity was abrogated by trypsin digestion and heat treatment. These results suggest that IFNg-treated mouse hepatocytes may release a soluble mediator(s) which suppressed the proliferation of hepatoma cells and that IFNg interactions with hepatocytes could be important to the antitumor defense mechanisms of the liver.

Suppression of cytochrome P450 (Cyp1a-1) induction in mouse hepatoma Hepa-1C1C7 cells by methoxsalen

Cultured mouse hepatoma cell line Hepa-1c1c7 cells were treated with methoxsalen to assess the role of methoxsalen in the process of Cyp1a-1 induction. Treatment of Hepa-1c1c7 cultures with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced Cyp1a-1, as indicated by analysis of 7-ethoxyresorufin O-deethylation (EROD) activity and P4501A1 protein. When methoxsalen and TCDD were both added to cultures, TCDD-inducible EROD activity was greatly suppressed by methoxsalen in a dose-dependent manner. We find that treatment of Hepa-1c1c7 cells with methoxsalen inhibited CYP1A1 mRNA induction by TCDD as well as the concomitant increase P4501A1 protein. Formation of DNA-protein complexes between the dioxin receptor and its DRE target was inhibited by methoxsalen, as determined by gel mobility shift assays using oligonucleotides corresponding to DRE 3 of the Cyp1a-1 gene. These results suggest that the inhibitory action of methoxsalen on TCDD induction of the Cyp1a-1 gene expression in Hepa-1c1c7 cells might be antagonism of the DNA binding potential of nuclear dioxin receptor.

Oxidation of the angiotensin II receptor antagonist losartan (DuP 753) in human liver microsomes. Role of cytochrome P4503A(4) in formation of the active metabolite EXP3174

The oxidative metabolism of losartan (DuP 753), a novel angiotensin II receptor antagonist, by human liver microsomes and purified cytochrome P450 (P450) enzymes, was studied. The primary route of metabolism of losartan is by oxidation of the C5-hydroxymethyl to the carboxylic acid (EXP3174), which is an active metabolite of losartan. When microsomes prepared from different human liver samples were compared, EXP3174 formation activity was well correlated (r2 = 0.93) with nifedipine oxidation (a marker of P4503A4), but not with markers for other human liver P450s. Microsomal oxidation of losartan to EXP3174 was markedly inhibited by gestodene and ketoconazole, selective inhibitors of P4503A enzymes, but not by any of several other P450 inhibitors. Antibodies raised against P4503A4 could inhibit most of the oxidation of losartan to EXP3174 in a microsomal sample having high catalytic activity, but antibodies recognizing other P450s had no effect. The oxidation of losartan to EXP3174 was catalyzed by purified human liver microsomal P4503A4 and by purified bacterial recombinant P4503A4. These results provide evidence that P4503A4 (and possibly other P4503A enzymes) play a major role in the formation of an active metabolite EXP3174.

Serum modulation of the effects of TCDD on the in vitro antibody response and on enzyme induction in primary hepatocytes

We have recently reported that the effects of TCDD on the in vitro antibody response can vary considerably depending on the serum conditions used in the culture media. To further investigate this phenomenon, studies were performed to compare the effects of TCDD on both splenocyte antibody responses and P450 enzyme induction (EROD) in primary hepatocytes (HPTC) derived from B6C3F1 and DBA/2 mice when evaluated in the presence of either fetal bovine serum (FBS), newborn calf serum (NBCS) or normal mouse serum (NMS). The latter studies with NMS also included crossovers where splenocytes and HPTC from B6C3F1 mice were cultured in the presence of DBA/2 serum and vice versa. Results with NBCS showed comparable suppression of antibody responses by TCDD in splenocytes from B6C3F1 and DBA/2 mice where we detected IC50 values of 3.0 and 2.8 nM, respectively. In contrast, responses in the presence of NMS showed an Ah-dependency that was characterized by a dose-related suppression of antibody responses by B6C3F1 splenocytes, but a lack of suppression in the responses by DBA/2 splenocytes. Distribution studies with radiolabelled TCDD indicated that the observed profile of activity could not be attributed to a differential uptake of the chemical into splenocytes from B6C3F1 or DBA/2 under the various serum conditions. Serum was also found to modulate the TCDD-induced EROD activity in primary HPTC and the profile of activity was identical to the effects of TCDD on in vitro antibody responses. We observed an enhanced induction of EROD in the presence of NBCS (immunosuppressive conditions) and a lower induction in the presence of FBS (non-immunosuppressive conditions), each giving the same relative magnitude of induction regardless of the mouse strain used as the source of HPTC. In contrast, induction in the presence of NMS showed an Ah-dependency and resulted in a dose-related enhancement in EROD activity in B6C3F1 HPTC but decreased activity in the DBA/2 HPTC. Cross-over studies further showed that the pattern of effects on both splenocytes and HPTC was not altered by changing the strain of mouse used as the source of serum, where each gave equivalent results. These findings demonstrate that the Ah-dependency for the effects of TCDD on both the in vitro antibody response and P450 enzyme induction are modulated by the serum environment in which the cells are exposed. The studies with NMS indicate that it is the genotype of the lymphocyte (i.e., or the HPTC), and not the strain-specific hormone environment, which confers sensitivity to TCDD.(ABSTRACT TRUNCATED AT 400 WORDS)

Direct effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on human tonsillar lymphocytes

Murine lymphocyte function is quite sensitive to TCDD. However, in contrast to the murine model, the corresponding functional studies have not been undertaken with human lymphocytes. One laboratory has recently demonstrated that human tonsillar lymphocytes (HTL) possess the aryl hydrocarbon (Ah) receptor which mediates many of the effects of TCDD. This observation suggested that HTL may be sensitive to TCDD. In mitogen stimulated HTL, TCDD induced a dose-dependent increase in 7-ethoxyresorufin-O-deethylase (EROD) synthesis. Because we recently demonstrated that background proliferation in HTL and murine splenocytes was suppressed by TCDD, we purified human and murine B-cells into high density and low density populations. In low density human B-cells, TCDD suppressed background proliferation and IgM secretion from 0.3 to 30 nM. Interestingly, TCDD produced comparable effects on background proliferation and IgM secretion in purified low density murine B-cells. When low density human B-cells were stimulated with LPS and TRF, TCDD suppressed both proliferation and IgG secretion in a dose-dependent manner from 0.3 to 30 nM, although the suppression was modest when compared to the magnitude of suppression of the background responses. In contrast, TCDD did not alter background or stimulated proliferation in high density human B-cells. These results indicate that TCDD has a direct effect on human tonsillar lymphocyte activity and suggest that low density B-cells are a sensitive cellular target.

Mouse interferon gamma pretreated hepatocytes conditioned media suppress cytochrome P-450 induction by TCDD in mouse hepatoma cells

Mouse interferon gamma (IFN-G) markedly suppressed 7-ethoxyresorufin o-deethylase (EROD) activity when added at the same time as TCDD in mouse primary hepatocyte cultures. IFN-G, however, had no effect on EROD induction by TCDD in Hepa-1 cells, a mouse hepatoma cell line, or Hepa-1 cells cocultured with Kupffer cells when added directly to the culture. EROD induction by TCDD in Hepa-1 cells was suppressed when cells were cultured with IFN-G pretreated mouse hepatocytes conditioned media. The magnitude of suppression was related to the dose of IFN-G and the density of hepatocytes used for the preparation of the conditioned media. Treatment of the monoclonal antibody against IFN-G to the conditioned media did not block the suppression of EROD induction. The suppressive effect of IFN-G pretreated hepatocytes conditioned media on EROD induction, however, was blocked when the conditioned media was heated or treated with trypsin. These results suggested that IFN-G pretreated mouse hepatocytes may release a soluble protein factor(s) which suppressed the EROD induction by TCDD in Hepa-1 cells.

Induction of cytochrome P-450 by dimethyl sulfoxide in primary cultures of adult rat hepatocytes

Treatment of hepatocyte cultures with dimethyl sulfoxide (DMSO) induced P-450IIE1-specific aniline 4-hydroxylase activity and P-450IA1-specific ethoxyresorufin O-deethylase activity at a concentration of 0.1% (v/v). The P-450IIB-specific pentoxyresorufin O-deethylase activity was induced only at the 2% (v/v) level. Dot blot analysis of the total cellular RNA and cycloheximide treatment of the culture suggested that induction of ethoxyresorufin O-deethylase activity by DMSO may be due to the increase of de novo synthesis of the P-450IA1 protein, not to accumulation of mRNA in the hepatocyte culture.