Neonatal exposure to bisphenol A alters rat uterine implantation-associated gene expression and reduces the number of implantation sites

Endocrine disrupters have been associated with reproductive pathologies such as infertility and gynecological tumors. Using a rat model of early postnatal exposure to bisphenol A (BPA), we evaluated the long-term effects on 1) female reproductive performance, 2) uterine homeobox A10 (Hoxa10) and Hoxa10-target gene expression, and 3) ovarian steroid levels and uterine estrogen receptor α and progesterone (P) receptor expression. Newborn female rats received vehicle, BPA.05 (0.05 mg/kg · d), BPA20 (20 mg/kg · d), diethylstilbestrol.2 (0.2 μg/kg · d), or diethylstilbestrol 20 (20 μg/kg · d) on postnatal d 1, 3, 5, and 7. A significant decrease in the number of implantation sites was assessed in the xenoestrogen-exposed females. To address the molecular effects of postnatal xenoestrogen exposure on the pregnant uterus, we evaluated the expression of implantation-associated genes on d 5 of pregnancy (preimplantation uterus). All xenoestrogen-treated rats showed a lower expression of Hoxa10. In the same animals, two Hoxa10-downstream genes were misregulated in the uterus. β(3) Integrin, which is up-regulated by Hoxa10 in controls, was decreased, whereas empty spiracles homolog 2, which is down-regulated by Hoxa10, was increased. Furthermore a clear down-regulation of estrogen receptor α and P receptor expression was detected without changes in estradiol and P serum levels. The early exposure to BPA produced a lower number of implantation sites in association with a defective uterine environment during the preimplantation period. Alterations in the endocrine-regulated Hoxa10 gene pathways (steroid receptors--Hoxa10--β(3) integrin/empty spiracles homolog 2) could explain, at least in part, the BPA effects on the implantation process.     

Differential tissue expression and activation of p38 MAPK α, β, γ, and δ isoforms in rheumatoid arthritis

Objective

Activation of p38 MAPK is a key signaling step in chronic inflammation. Inhibition of p38 MAPK is considered to be a promising future strategy to control inflammatory diseases, but studies of compounds to inhibit this kinase have so far been limited to investigation of their side effects. We undertook the present study to investigate which specific molecule, among 4 different isoforms of p38 MAPK (α, β, γ, and δ), is predominantly expressed and activated in inflammation. Such knowledge could allow more specific targeting of p38 MAPK in inflammatory disease.

Methods

Studies were performed on inflamed tissue from patients with rheumatoid arthritis, as a prototype of inflammatory disease. The expression and activation of the α, β, γ, and δ isoforms of p38 MAPK were examined by immunoblotting, immunoprecipitation, and immunohistochemistry.

Results

Immunoblot analysis revealed that α and γ were the predominantly expressed p38 MAPK isoforms, whereas the other 2 isoforms were less frequently present. By immunohistochemistry, the expression of all p38 MAPK isoforms was localized to the synovial lining layer as well as to blood vessels. Colabeling with cell‐specific markers revealed that macrophages expressed the α and γ isoforms, synovial fibroblasts the β and γ isoforms, and granulocytes the δ isoform, whereas T lymphocytes were rarely positive for any p38 MAPK isoform. Double‐labeling with isoform‐specific antibody and pan‐p38 antibody against the phosphorylated form of p38 MAPK showed activation of the α and γ isoforms. Occasional activation of the β isoform was also noted in the synovial lining and the endothelium, whereas the δ isoform, although expressed in pericytes around blood vessels, was not phosphorylated. This phosphorylation pattern was confirmed in immunoprecipitation studies in which activated p38 MAPK from synovial tissue extracts was identified as p38 MAPKα and ‐γ but not p38 MAPKβ or ‐δ.

Conclusion

These data show that the α and γ isoforms of p38 MAPK dominate in chronic inflammation. Effective strategies to inhibit p38 MAPK should therefore aim to specifically target either or both of these isoforms.

     

香烟烟雾暴露对支气管哮喘大鼠Th1/Th2细胞因子及转录因子GATA-3表达的影响

目的 通过观察香烟烟雾暴露后支气管哮喘(简称哮喘)大鼠Th1/Th2细胞因子及转录因子GATA-3表达的变化.探讨吸烟加重哮喘的免疫学机制.方法 48只雄性Wistar大鼠随机分为对照组、烟雾暴露组、哮喘组、哮喘+烟雾暴露组;建立慢性哮喘大鼠模型和哮喘大鼠香烟烟雾暴露模型,普通病理观察气道壁厚度的变化,酶联免疫吸附试验检测外周血和肺组织γ干扰素(INF-γ)和白介素4(IL-4)含量;免疫印迹检测肺组织GATA-3蛋白表达水平.结果 ①哮喘+烟雾暴露组气道壁厚度[(18.34±0.87)μm 2/μm]较哮喘组[(15.72±0.82)μm 2/μm]和对照组[(8.52±0.58)μm 2/μm]均明显增加,差异有统计学意义(P值均<0.01);②哮喘+烟雾暴露组血浆和肺组织IL-4含量[(34.07±6.11)ng/L]、[(1.41±0.31)ng/L]较哮喘组[(22.57±4.32)ng/L]、[(0.80±0.14)ng/L]和对照组[(11.38±2.90)ng/L]、[(0.27±0.08)ng/L]均增高,差异有统计学意义(P值均<0.05);哮喘+烟雾暴露组血浆INF-γ含量[(9.53±3.28)ng/L]较哮喘组[(58.83±19.57)ng/L]和对照组[(150.87±55.54)ng/L]均降低,差异有统计学意义(P值均<0.05),肺组织INF-γ含量[(0.48±0.10)ng/L]较哮喘组[(0.58±0.23)ng/L]差异无统计学意义;③哮喘+烟雾暴露组GATA-3蛋白表达(1.29±0.08)较哮喘组(0.87±0.04)和对照组(0.45±0.06)均增加,差异有统计学意义(P值均<0.01).结论 香烟烟雾暴露可以通过上调转录因子GATA-3蛋白表达,进而调控Th1/Th2偏移,在哮喘气道炎症及气道重塑的形成中扮演重要角色,为吸烟加重哮喘的免疫学机制之一.     

Oct-1, silencer sequence, and GC box regulate thyroid hormone receptor β1 promoter

Thyroid hormone, acting through thyroid hormone receptors (TRs), plays a crucial role in brain development and its insufficiency results in irreversible brain damage. TR mRNA is expressed continuously from early embryonic stages, but the level of TRβ1 mRNA in brain is more abundant in adult than in fetus. To identify important factors which regulate TRβ1 expression, we compared mouse fetal and adult brain nuclear extracts by DNase I footprinting and electrophoretic gel mobility shift assays (EMSA) of the TRβ1 promoter. We carried out transient transfection studies in COS 1 cells using the TRβ1 promoter fused to Luciferase gene, and used mutated promoter vectors and various expression vectors. In DNase I footprinting using the fragment -950 to -717, fetal brain nuclear extracts protected the areas -910 to -884 and -815 to -800 more than did adult extracts. In EMSA, proteins in fetal nuclear extracts bound to a silencer sequence (−924 to -916), GC box (−901 to -887), and E box (−810 to -805), more strongly than did proteins in adult brain extracts. The bands formed on GC box were not supershifted by Sp-1, Sp-2, Sp-3, Sp-4, EGR-1, or EGR-2 antibodies. Three bands were detected on the octamer binding site probe (−913 to -906) and one protein was supershifted by Oct-1 antibody. Adult brain extracts appear to contain more Oct-1 protein than do fetal extracts. The other two bands were more intense in fetal extracts than in adult extracts, but were not supershifted by either Oct-1 or Oct-2 antibodies. Mutation of the silencer response element, mutation of the GC box, and Oct-1 over expression in COS 1 cells increased TRβ1 promoter function as assayed by Luciferase reporter. Mutation of the octamer binding site, to which only Oct-1 bound in COS 1 cells, decreased Luciferase reporter activity. Thus the TRβ1 promoter was regulated negatively by the proteins bound to the silencer sequence and the GC box, and positively by Oct-1. Silencer and GC box binding proteins are more abundant in fetal brain, and Oct-1 is more abundant in adult brain. The results may be responsible for increased amounts of TRβ1 present in late fetal and adult brain.     

Prenatal exposure of rats to staphylococcal enterotoxin B alters the expression of Th1 and Th2 cytokines via decreased methylation in the spleen of adult but not neonatal offspring

Background: The methylation of IFN-γ and IL-4 genes is regarded as an epigenetic regulation that maintains the Th1 or Th2 phenotype. Objective: To explore the influence of prenatal administration of the staphylococcal enterotoxin B (SEB) in pregnant rats, on the IFN-γ or IL-4 expression in the offspring spleen. Methods: The SEB or PBS was administered intravenously to pregnant rats on the embryo-day 16. After normal delivery, the spleens from the fifth-day neonates and adult offspring were isolated under anesthesia. Quantitative PCR, western blot, ELISA and MeDIP-qPCR were applied to determine the levels of the splenic IFN-γ or IL-4 mRNAs, their protein levels, and methylation status, respectively. Results: Prenatal administration of the SEB in pregnant rats decreased the levels of the splenic IFN-γ and IL-4 proteins in neonates, but increased their mRNA levels. However, prenatal administration of the SEB significantly augmented both mRNA and protein levels of the IFN-γ and IL-4 in the adult spleen. In addition, the prenatal SEB administration decreased the methylation of the splenic IFN-γ and IL-4 in adult but not neonatal offspring. Conclusion: The prenatal administration of SEB in pregnant rats can cause a mixed Th1 and Th2 cytokines response in the offspring spleen, and alter the cytokine expression of the Th1 and Th2 via decreasing the methylation in adult but, not neonatal offspring spleen.     

Postnatal expression of cytochrome P450 1A1, 2A3, and 2B1 mRNA in neonatal rat lung: influence of maternal nicotine exposure

A critical factor contributing to the etiology or modification of respiratory disease is the ability of the lung tissue to activate or inactivate chemicals. In this study, the authors investigated the effect of maternal nicotine exposure during gestation and lactation on the expression mRNA of cytochrome P450 (CYP) CYP1A1, CYP2A3, and CYP2B1. Fetal rats were exposed to nicotine via maternal administration of nicotine (1 mg/kg body weight/day, subcutaneously); after birth, neonatal rats were exposed to nicotine via the mother's milk. Lung tissue of 1-, 7-, 14-, 21-, and 49-day-old rat pups were used. From weaning on postnatal day 21 up to postnatal day 49, the offspring received no nicotine. Using RNA dot-blot techniques, our results show that CYP mRNA expression in lung tissue increased with age after birth. Maternal nicotine exposure had no influence on CYP1A1 mRNA, but resulted in a marked increase in the expression of CYP2A3 mRNA and CYP2B1 mRNA. The higher levels of CYP2A3 mRNA and CYP2B1 mRNA were maintained after weaning.     

Decreased expression of the C3b/C4b receptor (CR1) and the C3d receptor (CR2) on B lymphocytes and of CR1 on neutrophils of patients with systemic lupus erythematosus

Decreased numbers of complement receptor type 1 (CR1) have been observed on erythrocytes of patients with systemic lupus erythematosus (SLE) and on glomerular podocytes of patients having proliferative nephritis of SLE. In the present study, the analysis of the cellular expression of CR1 has been extended to include leukocytes. In addition, expression by B lymphocytes of the C3d receptor (CR2), which also serves as the receptor for the Epstein-Barr virus, was assessed. Receptor expression was measured by 2-color fluorescent flow cytometry of peripheral blood B cells, identified by the presence of the B1 antigen, that had also been stained with anti-CR1 or anti-CR2. B cells from 17 patients with SLE exhibited a mean relative fluorescence for CR1 that was 61% of that found in 17 normal individuals (P less than 0.001). The expression of CR2 by the patients' B cells (n = 14) was 62% of that of the B cells from normal subjects (n = 17) (P less than 0.001). The expression of CR1 correlated with that of CR2 among patients (r = 0.63; P less than 0.01) but not with the expression of CR2 among normal individuals (r = 0.36; P greater than 0.1). The mean CR1 content of the patients' neutrophils was only 59% of the normal mean (P less than 0.001). Thus, abnormalities of complement receptor expression occur on the leukocytes of patients with SLE. These deficiencies may be secondary to interaction of the cells with the products of complement activation, or, in some individuals, the deficiencies may be familial.     

三氧化二砷和肿瘤坏死因子相关凋亡诱导配体诱导的髓系恶性细胞系P15ink4b表达

目的:观察骨髓增生异常综合征(MDS)髓系原始细胞系MDS-L及髓系白血病细胞系ML1经不同剂量和不同时间的三氧化二砷(As2O3)和肿瘤坏死因子相关凋亡诱导配体(TRAIL)处理后的抑癌基因P15ink4b变化。并研究DNA甲基化转移酶DNMT1在P15ink4b变化中的可能作用。方法:体外培养的MDS-L和ML1细胞经9种不同浓度的药物处理(As2O31 mmol/L;2 mmol/L;5 mmol/L;TRAIL 100μg/L;300μg/L;500μg/L;As2O31 mmol/L加Trail 100μg/L;As2O32 mmol/L加TRAIL 300μg/L;As2O35 mmol/L加TRAIL 500μg/L),在24 h、48 h和72 h后收获细胞。未经药物处理的细胞和药物处理后收获的细胞均提取总RNA,经半定量RT-PCR检测P15ink4bmRNA表达。对MDS-L细胞还同时检测DNMT1表达;正常人和5例MDS病例的P15ink4b和DNMT1检测作为对照。结果:未经处理的MDS-L和ML1细胞基本不表达P15ink4b,药物处理后P15ink4b表达增强;药物诱导MDS-L细胞表达P15ink4b的作用强于ML1细胞;未经处理的MDS-L和ML1细胞高表达DNMT1,药物处理24 h后DNMT1不同程度下降,但DNMT1表达状况与P15ink4b表达增强不显示相关性。结论:As2O3和(或)TRAIL处理能促进髓系恶性细胞抑癌基因P15ink4b表达,但并非主要通过抑制DNMT1功能而起作用。     

Transcriptional regulation of human thyroid hormone receptor β1 gene expression: effect of human retinoid X receptor and identification of a transcriptional silencer region

Effects of human retinoid X receptor (hRXR) and its ligand, 9-cis-retinoic acid, on T₃-mediated auto-regulation of hTRβ1 gene expression were examined using a chloramphenicol acetyltransferase (CAT) reporter system, and a deletional analysis of the promoter. hRXR enhanced T₃-dependent CAT induction mediated through the proximal (p) TRE in a ligand (9-cis-retinoic acid) independent manner. In a gel mobility shift assay, hRXR enhanced the binding of hTRβ1 to the pTRE by the formation of hRXR-hTRβ1 heterodimers. On the other hand, hRXR and 9-cis-retinoic acid did not show any effects on T₃-dependent CAT induction mediated through the distal (d) TRE or the binding of hTRβ1 to the dTRE. A four hundred-base pair (bp) fragment adjacent upstream of the dTRE showed a T₃ independent suppresser effect on the function of the pTRE and dTRE. Thus, this region may be an important regulator of the T₃ dependent up-regulation of the TRβ1 gene expression which is observed only under specific conditions.