Search PubMed⌕ Search

Biomedical subjects

J S Hunt

Publications and source records attributed to J S Hunt.

At least 55 records · Page 3Linked to original sources
PubMed1996

Progesterone inhibits inducible nitric oxide synthase gene expression and nitric oxide production in murine macrophages.

The purpose of this study was to determine whether the female hormones estradiol-l7 beta (E2) and progesterone (P4) influence inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) by interferon-gamma(IFN-gamma)-and lipopolysaccharide (LPS)-activated mouse macrophages. Treatment with P4 alone caused a time- and dose-dependent inhibition of NO production by macrophage cell lines (RAW 264.7, J774) and mouse bone marrow culture-derived macrophages as assessed by nitrite accumulation. RAW 264.7 cells transiently transfected with an iNOS gene promoter/luciferase reporter-gene construct that were stimulated with IFN-gamma/LPS in the presence of P4 displayed reduced luciferase activity and NO production. Analysis of RAW 264.7 cells by Northern blot hybridization revealed concurrent P4-mediated reduction in iNOS mRNA. These observations suggest that P4-mediated inhibition of NO may be an important gender-based difference within females and males that relates to macrophage-mediated host defense.

Animals↗
PubMed1996

Sex steroid hormones and macrophage function.

Macrophages are versatile cells whose activities are programmed by environmental signals. In this review, we discuss the potential impact of sex steroid hormones on macrophage activation and production of various effector molecules. The evidence accumulated to date supports the postulate that estrogens, progesterone, androgens and testosterone profoundly influence host defense by controlling the ability of macrophages to participate in immune responses.

Androgens↗
PubMed1996

Expression of the transporter for antigen processing-1 (Tap-1) Gene in subpopulations of human trophoblast cells.

Heterodimers of transporter for antigen processing proteins, Tap-1 and Tap-2, are essential components of the pathway that leads to expression of conventional HLA-A, -B class I transplantation antigens on cell surfaces. In this study, expression of the Tap-1 gene in trophoblast cells, some of which display novel and unconventional HLA class I molecules that include HLA-G and an HLA-C-like antigen, was investigated by using in situ hybridization to identify Tap-1 mRNA and immunohistochemistry to detect Tap-1 protein. The experiments were done on semiserial sections of paraformaldehyde-fixed tissues. In first trimester placentas, expression of the Tap-1 gene correlated with expression of HLA class I antigens in trophoblast cells. HLA-G/C positive extravillous cytotrophoblast cells exhibited high intensity in situ hybridization signals for Tap-1 mRNA and strong staining with anti-Tap-1 whereas Tap-1 gene products were rarely detected in HLA class I antigen negative syncytiotrophoblast and villous cytotrophoblast cells. Relationships were less definitive in term tissues. Although Tap-1 protein was detectable in extravillous cytotrophoblast cells (chorionic cytotrophoblast cells) as expected, HLA class I negative syncytiotrophoblast contained low intensity hybridization and immunostaining signals. Collectively, the data suggest that (1) as with conventional HLA class I antigens in other types of cells, the pathway leading to expression of novel HLA class I antigens in trophoblast cells includes transport of peptides by Tap-1, and that (2) deficiencies in Tap-1 might account in (whole or in) part for the failure of some trophoblast cells to express HLA class I antigens.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Uterine macrophages and environmental programming for pregnancy success.

Macrophages are ubiquitous cells with an impressive range of functions. These include phagocytosis and coordination of the initiation and effector phases of immune responses, as well as production of bioactive proteins and lipids that profoundly influence cell growth, differentiation and function. Macrophages are highly individualized in tissues, where their activities are a reflection of targeting by systemic and local environmental signals. This review focuses on recent studies where uterine macrophage population densities and distribution have been mapped, chemotaxis, differentiation and activation have been investigated and production of potent effector molecules has been explored. Evidence supporting a major role for female sex steroid hormones and the uterine growth factors they control in governing these features of uterine macrophages is presented.

Animals↗
PubMed1996

Tumor necrosis factors: pivotal components of pregnancy?

Tumor necrosis factor alpha is a major component of the infection-stimulated cytokine milieux associated with preterm labor and pregnancy termination. As a consequence, this potent factor is thought by some to have exclusively negative effects on the course of pregnancy. Yet in humans and other mammals, messenger RNA hybridizing with tumor necrosis factor alpha cRNA probes and protein detected by anti-tumor necrosis factor alpha have been identified in normal cycling and pregnant uteri, placentas, and embryos, consistent with an important role for tumor necrosis factor in female reproduction and embryonic development. Here, evidence for this intriguing dichotomy is presented, unresolved aspects are discussed, and potential roles for uteroplacental and embryonic tumor necrosis factor are proposed.

Embryo, Mammalian↗
PubMed1996

Cellular localization and steroid hormone regulation of mRNA encoding tumour necrosis factor receptor I in mouse uterus.

Signals transduced by binding of tumour necrosis factor alpha (TNF) and lymphotoxin alpha (LT-alpha) trimers to high-affinity cell membrane receptors, TNF-RI (p55/p60) and TNF-RII (p75/p80), affect many cell functions. In this study, expression of the gene encoding TNF-RI in uteri of cyclic mice was mapped using in situ hybridization. TNF-RI hybridization signals fluctuated during the cycle. Signal intensity was highest during dioestrus-II, when mRNA encoding TNF-RI was present in endometrial epithelial and stroma cells, as well as in myometrial smooth muscle and connective tissue cells. The ability of oestradiol and progesterone to modulate steady state concentrations of mRNA encoding TNF-RI in uterine cells was assessed by using in situ and northern blot hybridization procedures. Seven days after ovariectomy, low concentrations of mRNA encoding TNF-RI were detected by northern analysis and weak in situ hybridization signals were identified in epithelia and some myometrial connective tissue cells. Administration of oestradiol, progesterone or oestradiol plus progesterone to ovariectomized animals stimulated temporal and cell type-specific changes in steady state concentrations of mRNA encoding TNF-RI that were unique to each hormonal regimen. Maximal induction of mRNA encoding TNF-RI required 24 h of oestradiol stimulation and 72 h of progesterone stimulation. In uteri treated with oestradiol plus progesterone, the oestradiol pattern predominated over the progesterone pattern. Thus, multiple cell types in cyclic mouse uteri express the gene encoding TNF-RI, and expression in specific cells is controlled by female steroid hormones.

Animals↗
PubMed1995

Temporal and spatial expression of HLA-G messenger RNA in extraembryonic tissues of transgenic mice.

HLA-G, a nonclassical class I molecule, is expressed by trophoblasts, the only fetal cells in direct contact with maternal tissue. Results of previous experiments suggested that a 244-bp region located over 1 kb 5' from exon 1 is critical for extraembryonic expression of HLA-G in transgenic mice. We report here the production of HLA-G transgenic lines with a 6.0-kb HLA-G transgene that includes the 244-bp region. These lines exhibit copy number-dependent and developmentally appropriate transgene expression. One HLA-G transgenic line, G.3.2, exhibits extraembryonic HLA-G mRNA expression levels similar to those seen in human extraembryonic tissues. Studies of the cell-type-specific localization of HLA-G mRNA in placentas from the G.3.2 HLA-G transgenic mouse line show predominant localization of the HLA-G message in the spongiotrophoblast layer. This layer is in a similar anatomic location to the HLA-G-expressing human cytotrophoblast shell. The G.3.2 HLA-G transgenic mouse line should serve as an appropriate model for the study of HLA-G function at the maternal-fetal interface.

Animals↗
PubMed1995

Cellular localization and hormonal regulation of inducible nitric oxide synthase in cycling mouse uterus.

Nitric oxide (NO), a potent and versatile free radical, is synthesized in macrophages and mast cells as well as in other types of cells by the inducible form of nitric oxide synthase (iNOS). In this study, cells containing iNOS were identified in the uteri of cycling mice by using a rabbit antibody generated to an iNOS-specific peptide. Macrophages were identified in semiserial sections of the same tissues with the monoclonal antibody, F4/80, and mast cells were identified by toluidine blue staining. In tissue sections of uteri obtained from mice in the four stages of the estrous cycle (8 to 11 mice per stage), iNOS immunoreactivity was strongest in diestrus-I uteri and weakest in diestrus-II uteri. Myometrial mast cells and endometrial epithelial cells were prominent locations of iNOS, and specific protein was also present in myometrial smooth muscle and macrophage-like cells in the endometrial stroma. Because cyclic variations suggested regulation of iNOS expression by ovarian steroid hormones, studies were done using ovariectomized mice. Seven days after ovariectomy, immunoreactive iNOS was low but detectable in mast cells and luminal epithelial cells. In the uteri of ovariectomized, estradiol-17 beta (E2)-treated mice, mast cells were iNOS+ after 24 h whereas epithelial cells were negative; the reverse was observed in progesterone (P4)-treated mice. Both mast cells and epithelial cells were iNOS+ in the uteri of mice that had received a combination of E2 + P4. These results indicate that several types of uterine cells produce iNOS and that expression of this enzyme in specific cell lineages is governed by ovarian steroid hormones. The data are consistent with the postulate that NO derived from uterine leukocytes and other types of cells plays a role in uterine cyclicity and preparation for pregnancy.

Amino Acid Oxidoreductases↗
PubMed1995

Synthesis and granular localization of tumor necrosis factor-alpha in activated NK cells in the pregnant mouse uterus.

The synthesis and cellular localization of tumor necrosis factor-alpha (TNF-alpha) were studied in mouse GMG cells, which are activated NK cells in uterine decidual tissue during pregnancy. Synthesis of the protein was demonstrated in GMG cells on days 10 and 14 of pregnancy by in situ hybridization of TNF-alpha message. Immunostaining demonstrated that TNF-alpha protein was localized in the cytoplasmic granules of GMG cells at these times. The results suggest that the cytolytic activity of uterine NK cells may be due in part to TNF-alpha, and that this cytokine may be delivered to target cells intracellularly via transmembrane pores formed by perforin, which is also localized in uterine NK cell granules.

Animals↗
PubMed1995

Cytokine regulation of HLA-G expression in human trophoblast cell lines.

HLA class I genes are differentially expressed among subpopulations of cells in first trimester human placentas. In this study, HLA class I protein was detected in extravillous cytotrophoblast cells by immunohistochemistry using the monoclonal antibody W6/32. In the same trophoblast subpopulation, class Ib proteins were identified with two monoclonal antibodies, 87G (anti-HLA-G) and 131 (anti-HLA-A/G) and class Ia protein was detected with the monoclonal antibody, 4E (anti-HLA-B/C). All of the antibodies also identified antigens on the human trophoblast-derived choriocarcinoma cell line, JEG-3. Therefore, the JEG-3 cells were used as a model system to study cytokine regulation of HLA-G in trophoblast cells. Northern blot hybridization studies showed that interferons (IFN-alpha, IFN-beta, IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) modestly enhanced steady state levels of HLA-G mRNA. Yet analysis of HLA-G protein by immunocytochemistry and flow cytometry failed to identify any changes in intracellular or membrane expression of HLA-G protein following cytokine treatment. Resistance to upregulation of HLA class I antigens was not a general feature of JEG-3 cells; IFNs enhanced expression of HLA-B/C as well as HLA class I light chain, beta 2-microglobulin. HLA null Jar choriocarcinoma cells did not contain HLA-G mRNA or antigen and exposure to cytokines had no effect on HLA-G. The results of this study are consistent with the postulate that trophoblast cell expression of HLA-G is stringently regulated and is controlled in part by post-transcriptional mechanisms.

Cell Line↗
PubMed1995

Myometrial tumor necrosis factor alpha: cellular localization and regulation by estradiol and progesterone in the mouse.

The expression of tumor necrosis factor alpha (TNF) protein in mouse myometrial cells on each day of the estrous cycle and after ovariectomy, with and without replacement of estradiol (E2), progesterone (P4), or E2 + P4, was investigated. TNF protein was assessed by immunocytochemistry. In addition, the numbers of mast cells and the numbers of TNF-containing mast cells were determined under each condition. The total number of mast cells fluctuated during the estrous cycle; and at each stage, essentially 100% of the mast cells exhibited TNF immunoreactivity. In contrast, after ovariectomy and after ovariectomy with E2 replacement, only approximately 50% of the mast cells contained immunoreactive TNF. P4 treatment resulted in further decline in mast cell TNF whereby after 24 h of P4, only 3% of the mast cells were TNF-positive and by 72 h of treatment, no TNF-positive mast cells could be detected E2 and P4 in combination increased the total number of mast cells, and in a pattern reminiscent of normal cycling myometrium, over 90% of the mast cells exhibited TNF immunoreactivity after 24 h of treatment. TNF protein was detectable in muscle cells throughout the estrous cycle, with weak immunostaining observed on proestrus and more intense immunostaining on estrus, diestrus-I, and diestrus-II. After ovariectomy, only light immunostaining was observed in the muscle cells. Immunoreactive TNF was detected in muscle cells after each type of steroid treatment. E2 and E2 + P4 treatments resulted in a biphasic pattern of immunoreactive TNF expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

A cautionary note.

Explore the source record for details and available documents.

Abortion, Habitual↗
PubMed1995

Targeted disruption of the low-affinity leukemia inhibitory factor receptor gene causes placental, skeletal, neural and metabolic defects and results in perinatal death.

The low-affinity receptor for leukemia inhibitory factor (LIFR) interacts with gp130 to induce an intracellular signal cascade. The LIFR-gp130 heterodimer is implicated in the function of diverse systems. Normal placentation is disrupted in LIFR mutant animals, which leads to poor intrauterine nutrition but allows fetuses to continue to term. Fetal bone volume is reduced greater than three-fold and the number of osteoclasts is increased six-fold, resulting in severe osteopenia of perinatal bone. Astrocyte numbers are reduced in the spinal cord and brain stem. Late gestation fetal livers contain relatively high stores of glycogen, indicating a metabolic disorder. Hematologic and primordial germ cell compartments appear normal. Pleiotropic defects in the mutant animals preclude survival beyond the day of birth.

Animals↗
PubMed1995

Tumor necrosis factor-alpha in the female reproductive tract.

Tumor necrosis factor-alpha (TNF), originally identified as an inflammation-associated cytokine, is synthesized throughout the female reproductive tract as well as in placentas and embryos. Development, female sex steroid hormones, and lipopolysaccharide influence expression of this gene. The functions of TNF may be determined in part by differential expression of the two species of TNF receptors, both of which seem to be regulated by female sex steroid hormones. Evidence has accumulated that supports a role for this potent, pleiotropic cytokine in autocrine and paracrine processes central to reproduction, including gamete and follicle development, steroidogenesis, uterine cyclicity, placental differentiation, development of the embryo, and parturition.

Animals↗
PubMed1995

Cellular distribution of proteasome subunit Lmp7 mRNA and protein in human placentas.

Human leucocyte antigen (HLA) class I antigen expression is closely controlled in placental trophoblast cells, which interface directly with genetically disparate maternal blood and tissues during pregnancy. In this study, the possibility that LMP7, a proteasome component that may be required for processing of class I-associated peptides, might be lacking or refractory to cytokine induction in trophoblast cells that fail to display HLA class I antigens was investigated. Analysis of Lmp7 mRNA and protein in paraformaldehyde-fixed placentas by in situ hybridization and immunohistochemistry revealed that both HLA class I-positive and HLA class I-negative trophoblast cells contain Lmp7 gene products. Consistent with these results, northern blot hybridization studies showed that HLA class I-positive (JEG-3) and HLA null (Jar) trophoblast-derived cell lines contain Lmp7 mRNA. After 48 hr of exposure to HLA class I-modulating cytokines, Lmp7 mRNA levels in JEG-3 cells were markedly increased by two interferons (IFN-beta, IFN-gamma) and tumour necrosis factor (TNF) whereas at the same time point, Jar cell Lmp7 mRNA was modestly enhanced by IFN-gamma. Collectively, the findings indicate that expression of HLA class I antigens in trophoblast cells is unlikely to be restricted by lack of Lmp7 gene products and suggest that endogenous placental cytokines may have different influences on Lmp7 mRNA levels in phenotypically distinct trophoblast subpopulations.

Blotting, Northern↗