Gender-based differences in cardiac repolarization in mouse ventricle.

The mouse heart has become a widely used model for genetic studies of heart diseases. Thus, understanding gender differences in mouse cardiac repolarization is crucial to the interpretation of such studies. The objective of this study was to evaluate whether there are gender differences in cardiac repolarization in mouse ventricle and to gain insights into the ionic and molecular mechanisms underlying these differences. Action potential durations (APDs) and K(+) currents in male and female ventricular myocytes were compared using a patch-clamp technique. APD(20), APD(50), and APD(90) were found to be significantly longer in females than males. Examination of the different K(+) currents revealed that a significantly lower current density exists in female ventricular myocytes compared with male myocytes for the ultrarapid delayed rectifier K(+) current, I(Kur) (at +30 mV, male, 33.2+/-2.9 pA/pF [n= 22]; female, 20.9+/-1.73 pA/pF [n= 19], P<0.001). Consistent with these findings were the results of the ribonuclease protection assay, Western blots, and confocal analysis that showed a significantly lower expression level of Kv1.5 (coding for I(Kur)) in female compared with male ventricle. The additional K(+) currents present in mouse ventricle exhibited no gender differences. In agreement with these electrophysiological data, no differences in the expression levels for the K(+) channels underlying these currents were detected between both sexes. This study demonstrates that adult mice exhibit gender differences in cardiac repolarization. The expression of Kv1.5 and of its corresponding K(+) current, I(Kur), is significantly lower in female mouse ventricle, and as a result, the APD is lengthened.

The IL-6-soluble IL-6Ralpha autocrine loop of endothelial activation as an intermediate between acute and chronic inflammation: an experimental model involving thrombin.

Thrombin is a procoagulant and proinflammatory molecule in vivo. In vitro, thrombin has been shown to induce endothelial activation, notably IL-8 secretion and adhesion molecule expression. In this study, we showed that thrombin may induce a new cascade leading from acute to chronic inflammation. Thrombin was able to induce the production of both IL-6 and monocyte chemotactic protein-1 (MCP-1) by HUVEC independently of IL-1alphabeta and TNF-alpha. Addition of physiological concentrations of exogenous soluble IL-6Ralpha (sIL-6Ralpha) to thrombin-activated HUVEC was sufficient to increase the amounts of MCP-1 produced, but not those of IL-8. These effects could be blocked by anti-IL-6 or anti-sIL-6Ralpha blocking mAb, demonstrating the existence of an autocrine loop of MCP-1 secretion, involving the IL-6/IL-6Ralpha/gp130 complex on HUVEC. In addition, we identified IL-8-activated neutrophils as a potential source of sIL-6Ralpha because IL-8 induced IL-6Ralpha shedding from the neutrophil membranes and increased in parallel sIL-6Ralpha concentrations in neutrophil supernatants. Furthermore, addition of neutrophils to thrombin-activated HUVEC significantly increased MCP-1 secretion, which could be decreased by blocking IL-6. Thus, thrombin-activated endothelium may induce a cascade of events characterized by IL-8 secretion, neutrophil local infiltration, and the release of IL-6Ralpha from neutrophil membranes. sIL-6Ralpha may then complex with IL-6 and increase the amount of MCP-1 produced by thrombin-activated endothelium, favoring monocyte infiltration, and the transformation of acute into chronic inflammation.

Phenotypic characterization of human CD4+ regulatory T cells obtained from cutaneous dinitrochlorobenzene-induced delayed type hypersensitivity reactions.

In this study, we describe the generation and characterization of cloned human CD4+ T lymphocyte populations that have infiltrated into cutaneous, 2,4-dinitrochlorobenzene-induced delayed type hypersensitivity reactions in healthy human subjects. It is shown that, in addition to T helper type 1 clones, elevated numbers of regulatory T clones, producing high levels of interleukin-10 and interleukin-5, but no measurable interleukin-4, were isolated from delayed type hypersensitivity reactions in four of six donors. A subsequent challenge with 2,4-dinitrochlorobenzene of two donors from whom only few interleukin-10-producing T cell clones had been generated after primary challenge, resulted in a decrease in the frequency of T helper type 1 clones and a strong increase in the number of interleukin-10-producing T helper type 2 and regulatory T clones. Culture supernatants from the latter cells, activated with anti-CD3 and anti-CD28 monoclonal antibody, inhibited alloantigen-mediated T cell proliferation which was, partly dependent on interleukin-10, and independent of transforming growth factor-beta. In addition, dendritic cells generated in vitro in the presence of these culture supernatants were impaired in their ability to induce alloantigen-induced proliferative responses. Differential expression of transcripts for the T1/ST2 molecule enabled a phenotypic distinction between resting regulatory T cells and T helper type 2 cells, but not between regulatory T cells and T helper type 1 cells. This experimental model provides a useful tool to isolate human inflammatory and anti-inflammatory T cell subpopulations and, furthermore, enables the study of the kinetics of their appearance into delayed type hypersensitivity reactions.

[Hypocomplementemic urticarial vasculitis]. / Vascularite urticarienne hypocomplémentémique.

BACKGROUND: Low-complement urticarial vasculitis is an uncommon condition associating urticaria, glomerulonephritis, obstructive ventilatory disorders, and anti-Ciq antibodies. CASE REPORT: We report a case in a 34-year-old woman who developed urticaria with purpura, membranoproliferative glomerulonephritis (creatinine 238 mumol/l) and bronchial obstruction with bronchectasia. Total complement and the C3 fraction were low. Anti-C1q antibodies were found in the serum and anti-DNA antibodies were negative. Aggravation of the respiratory and renal failure progressed despite corticosteroid therapy, leading to death at 4 months. DISCUSSION: Bronchial obstruction in low-complement urticarial vasculitis results from emphysema and is often life-threatening. Our case exhibited an unusual feature due to the lack of radiodetectable emphysema, the presence of bronchectasia and the rapid degradation of the respiratory function.

Thrombin-activated human endothelial cells support monocyte adhesion in vitro following expression of intercellular adhesion molecule-1 (ICAM-1; CD54) and vascular cell adhesion molecule-1 (VCAM-1; CD106).

Thrombin, a central molecule in coagulation, is also involved in inflammation. Notably, thrombin induces endothelial neutrophil adhesion, P- and E-selectin expression, and chemokine production. We show here that thrombin induces expression of intercellular adhesion molecule-1 (ICAM-1; CD54) and vascular cell adhesion molecule-1 (VCAM-1; CD106) on human umbilical vein endothelial cells (HUVECs) associated with increased adhesion of monocytes. Thrombin increased mRNA steady-state levels and expression of ICAM-1 over 24 hours. Thrombin-induced VCAM-1 expression exhibited unusual kinetics, reaching maximum levels after 6 to 12 hours, but decreasing to near baseline after 24 hours. Thrombin activity on HUVECs was mediated through interaction with its specific receptor, because ICAM-1 and VCAM-1 expression were similarly induced by the 14-amino acid thrombin receptor-activating peptide. Thrombin-induced ICAM-1 and VCAM-1 expression was significantly inhibited by hirudin, but not by interleukin-1 receptor antagonist or anti-tumor necrosis factor alpha monoclonal antibody (MoAb). Thrombin-activated HUVECs significantly increased greater numbers of adhering THP-1 macrophagic cells, peripheral blood mononuclear cells, or purified monocytes than unstimulated HUVECs. This adhesion was inhibited by anti-CD18 and anti-CD49d MoAb, demonstrating that thrombin-induced ICAM-1 and VCAM-1 were functional. These results show that, in addition to selectins, thrombin directly induces a cytokine-independent expression of adhesion molecules of the Ig superfamily on HUVECs that may support firm leukocyte attachment during inflammation.

[Angiosarcoma of the thoracic wall revealed by hemothorax]. / Angiosarcome de la paroi thoracique révélé par un hémothorax.

Angiosarcoma is an uncommon tumor accounting for approximately 1% of all soft tissue tumors which, themselves account for 0.7% of all malignant tumors. Thoracic parietal localizations are reported exceptionally and prognosis is poor. We report the case of a 79-year-old woman who developed an angiosarcoma of the thoracic wall. The inaugural symptom was a hemothorax. Besides the localization, this case was particularly exceptional since the patient has remained asymptomatic three years after treatment by wide resection followed by radiotherapy.

Thrombin induces endothelial type II activation in vitro: IL-1 and TNF-alpha-independent IL-8 secretion and E-selectin expression.

In addition to its role in coagulation, thrombin is involved in the inflammatory process by inducing vessel neutrophilic infiltration. Thrombin induces endothelial P-selectin expression and platelet activating factor release, which participate to induce early neutrophil adhesion and activation. We employed HUVEC and now show that thrombin induces the production of the chemokine IL-8 in a time- and dose-dependent fashion. Similarly, thrombin induced E-selectin expression on HUVEC. Both IL-8 secretion and E-selectin expression were preceded by an increase in steady state levels of the respective mRNAs. Thrombin action on HUVEC was inhibited by the specific thrombin inhibitor, hirudin. In addition, these effects of thrombin on HUVEC were mimicked by the 14-amino acid thrombin receptor agonist peptide, which triggers the native thrombin receptor in a similar fashion to thrombin itself. Although IL-1 and TNF-alpha also induce IL-8 and E-selectin, the thrombin effects in these experiments were not mediated by those cytokines, since neither IL-1 receptor antagonist nor anti-TNF-alpha Ab inhibited the effects of thrombin. Furthermore, IL-1alpha, IL-1beta, and TNF-alpha were not detected in the supernatants of thrombin-activated HUVEC. Although intracellular IL-1alpha was found in thrombin-activated HUVEC, antisense IL-1alpha had no inhibitory effect on IL-8 secretion. These results demonstrate that in addition to short term endothelial activation, thrombin also functions as a long acting proinflammatory agent by inducing endothelial synthesis of the mediators required for neutrophils activation and extravazation during inflammation.

A novel and atypical type one interferon gene expressed by trophoblast during early pregnancy.

Low stringency screening of day 14-15 pig conceptus cDNA library using an interferon (IFN)-omega probe has led to the isolation of a novel type one (type I) IFN gene physiologically expressed by trophoblast during the period of implantation in the uterus. It encodes a 170-amino acid preprotein with two potential N-glycosylation sites and a predicted N-terminal signal peptide of 21 residues. This protein was shorter and richer in Cys residues than other type I IFNs and distantly related to all of them including IFN-tau, the trophoblast IFNs of ruminants, with amino acid identities ranging between 27 and 42%. Moreover, its antiviral activity was resistant to neutralization by antisera directed against several IFN-alpha, -beta, -omega, and -tau family members. The pig genome contained only two intronless, non-allelic loci homologous to the cDNA, one of them corresponding to the cDNA. This gene had a single transcription initiation site. Its upstream putative regulatory regions had no similarity with those of other type I IFN genes and did not display the typical clustering of short sequence motifs thought to be involved in virus inducibility but, instead, a modular structure of 30-40-base pair direct repeats. These data highlight the very atypical characteristics of this gene and its product and suggest that it represents the first member of a yet unknown family of type I IFNs present in other mammalian species according to sequence divergence analysis.

Acquisition of hormone-independent growth in MCF-7 cells is accompanied by increased expression of estrogen-regulated genes but without detectable DNA amplifications.

A hormone-independent but hormone-responsive subpopulation (MCF7/MIII) of the hormone-dependent MCF-7 human breast cancer cell line (R. Clarke et al., Proc. Natl. Acad. Sci. USA 86: 3649-3653, 1989) was further passaged in ovariectomized nude mice and re-established in vitro as the continuous cell line MCF7/LCC1. The lag time to the appearance of proliferating tumors in ovariectomized animals is significantly reduced in MCF7/LCC1 when compared with MCF7/MIII cells. In gel denaturation/renaturation analysis of tumor, genomic DNA does not reveal significant differences in the pattern of detectable DNA amplifications between parent MCF-7 cells and MCF7/LCC1 cells. In the absence of estrogen, steady-state levels of phosphoinositol turnover are similar in both MCF-7 and MCF7/LCC1 cells, but turnover is increased by estrogen only in MCF-7 cells. MCF7/MIII and MCF7/LCC1, but not MCF-7 cells, express a high baseline level of the estrogen-regulated pS2 mRNA. The baseline level of expression of progesterone receptor protein, but not mRNA, is higher in MCF7/LCC1 when compared with either MCF-7 or early passage MCF7/MIII cells. However, while the estrogen receptor is also an estrogen-regulated gene, MCF7/MIII and MCF7/LCC1 cells retain estrogen receptor levels equivalent to the parental MCF-7 cells. These data indicate that progression to hormone independence can occur without major gene amplifications or a high constitutive induction of phosphoinositide metabolism. Thus, DNA amplifications may be acquired during the early initiation and/or promotional events of carcinogenesis. Significantly, acquisition of a hormone-independent but responsive phenotype in human breast cancer is associated with perturbations in the expression of specific estrogen-regulated genes.

The invasive and metastatic properties of hormone-independent but hormone-responsive variants of MCF-7 human breast cancer cells.

We have previously isolated a series of MCF-7 human breast cancer cell variants which no longer require estrogen-supplementation for tumor growth in nude mice (Clarke et al. Proc Natl Acad Sci USA 86: 3649-3653, 1989). We now report that these hormone-independent and hormone-responsive variants (MIII, MCF7/LCC1) can invade locally from solid mammary fat pad tumors, and produce primary extensions on the surface of intraperitoneal structures including liver, pancreas, and diaphragm. Both lymphatic and hematogenous dissemination are observed, resulting in the establishing of pulmonary, bone, and renal metastases. The pattern of metastasis by MIII and MCF7/LCC1 cells closely resembles that frequently observed in breast cancer patients, and provides the first evidence of metastasis from MCF-7 cells growing in vivo without supplementary estrogen. The interexperimental incidence of metastases, and the time from cell inoculation to the appearance of metastatic disease are variable. The increased metastatic potential is not associated with an increase in either the level of laminin attachment, laminin receptor mRNA expression, or secreted type IV collagenolytic activity. We also did not detect a significant decrease in the steady-state mRNA levels of the metastasis inhibitor nm23 gene. However, when growing without estrogen in vitro, MCF7/LCC1 cells produce elevated levels of the estrogen-inducible cathepsin D enzyme.

Effect of P-glycoprotein expression on sensitivity to hormones in MCF-7 human breast cancer cells.

BACKGROUND: Data obtained from studies of primary human breast cancers and established cell lines indicate that overexpression of the MDR1 gene (also known as PGY1) is associated with decreased expression of steroid hormone receptors and increased expression of epidermal growth factor (EGF) receptors. Other study results indicate that both progestins and triphenylethylene antiestrogens may be substrates for P-glycoprotein, the product of the MDR1 gene. These findings together suggest an association between overexpression of the MDR1 gene and cross-resistance to progestin and antiestrogen therapies. PURPOSE: This study was designed to determine (a) the ability of MDR1 expression to alter tumor sensitivity to hormone therapy and (b) the role of MDR1 expression in expression of functional hormone receptors in human breast cancer. METHODS: We transduced MCF-7 cells with MDR1 complementary DNA, using a retroviral vector directing the constitutive expression of the MDR1 gene. Transduced cells (MCF-7MDR1) were examined for ability to produce P-glycoprotein, expression of steroid hormone receptors, and responsivity to antiestrogens. For comparison, we used MCF-7ADR human breast cancer cells, which overexpress MDR1 and have also lost the requirement for 17 beta-estradiol supplementation to form tumors in nude mice. We also investigated the level of EGF-R mRNA expression by using a sensitive RNase protection analysis. RESULTS: MCF-7MDR1 cells retained both estrogen receptor and progesterone receptor expression as well as sensitivity to 4-hydroxytamoxifen. Expression of the estrogen-inducible pS2 and EGF receptor genes was similar in parental MCF-7 and transduced MCF-7MDR1 cells. EGF receptor expression was increased, and pS2 expression was lost (undetectable) in MCF-7ADR cells. CONCLUSIONS: The data indicate that overexpression of the MDR1 gene alone confers a multidrug-resistant phenotype, but it does not directly result in either cross-resistance to antiestrogens or a loss of steroid hormone receptor expression. IMPLICATIONS: MCF-7MDR1 cells provide an important model for study of the interactions of cytotoxic drugs, hormones, and the MDR1 glycoprotein in human hormone-responsive breast cancer cells.

The biology of breast tumor progression. Acquisition of hormone independence and resistance to cytotoxic drugs.

Many breast tumors appear to follow a predictable clinical pattern, being initially responsive to endocrine therapy and to cytotoxic chemotherapy but ultimately exhibiting a phenotype resistant to both modalities. Using the MCF-7 human breast cancer cell line as an example of an 'early' phenotype (estrogen and progesterone receptor positive, steroid responsive, low metastatic potential), we have isolated and characterized a series of hormone-independent but hormone-responsive variants (MIII and MCF7/LCC1). However, these variants remain responsive to both antiestrogens and cytotoxic drugs (methotrexate and colchicine). MIII and MCF7/LCC1 cells appear to mimic some of the critical aspects of the early progression to a more aggressive phenotype. An examination of the phenotype of these cells suggests that some hormone-independent breast cancer cells are derived from hormone-dependent parental cells. The development of a hormone-independent phenotype can arise independently of acquisition of a cytotoxic drug resistant phenotype.