Oxidative activity of the type 2 isozyme of 17beta-hydroxysteroid dehydrogenase (17beta-HSD) predominates in human sebaceous glands

Interactions between infiltrating T cells and keratinocytes via the secretion of the TH1 cytokines interleukin (IL) 2 and interferon gamma (INF-gamma), the keratinocyte growth factor transforming growth factor alpha (TGF-alpha) and the cytokines IL-6 and IL-8 are thought to be the predominant mechanisms inducing skin lesions in psoriatic patients. Systemic treatment of psoriasis with fumaric acid derivatives (FAEs) has been reported to be effective in the treatment of psoriasis, but the mode of action is still unknown. To clarify this phenomenon, keratinocytes from psoriatic patients as well as from healthy volunteers were mono- and cocultured with HUT 78 T cells with/without the addition of FAEs; the cytokine concentrations were then measured in the culture supernatants. Furthermore, mRNA expression was determined in epidermal growth factor (EGF) -activated keratinocytes as well as in phytohaemagglutinin (PHA)-activated HUT 78 T cells. Only dimethylfumarate (DMF) diminished IL-6 and TGF-alpha secretion in the psoriatic cocultures. However, it did not have this effect on cocultures from control subjects or on monocultures. DMF suppresses EGF-induced TGF-alpha mRNA induction in psoriatic keratinocytes. DMF inhibited INF-gamma secretion in all cultures but stimulated the IL-10 secretion. This immunomodulation away from the TH1 cytokine IFN-gamma to the TH2 cytokine IL-10 was confirmed in HUT 78 T cells by Northern blot analysis. An increased number of eosinophils is a known side-effect in patients treated with this drug, suggesting a clinical relevance of this immunomodulation in vivo. This immunomodulation and the suppression of cytokines from the psoriatic cytokine network could be responsible for the beneficial effect of DMF in the treatment of a hyperproliferative and TH1 cytokine-mediated skin disease.     

Immature rat ovaries become revascularized rapidly after autotransplantation and show a gonadotropin-dependent increase in angiogenic factor gene expression

When the ovaries of 23-day-old juvenile rats are transplanted to an ectopic site, they recover within 1 week the ability to control gonadotropin secretion via steroid negative feedback. Vascular corrosion casting followed by scanning electron microscopy revealed that the transplanted ovary becomes profusely revascularized within 48 h after transplantation. Vascular ingrowth was accompanied by a 40- to 60-fold increase in expression of the genes encoding two angiogenic factors, vascular endothelial growth factor (VEGF) and transforming growth factor-beta 1 (TGF beta 1), as assessed by RNA blot hybridization of the corresponding mRNAs. Although TGF beta 3 mRNA levels also increased, no changes in the levels of mRNAs encoding other putative angiogenic factors, such as TGF alpha, basic fibroblast growth factor, and TGF beta 2, were observed. Hybridization histochemistry demonstrated that in intact ovaries, VEGF mRNA is mainly expressed in granulosa cells of the cumulus oophorus and thecal cells of large antral follicles. Transplantation is followed by an increase in mRNA abundance and a dramatic shift in cellular localization, so that the mRNA becomes predominantly expressed in cells of the outer ovarian cortex. In intact ovaries, low levels of TGF beta 1 mRNA were detected in thecal-interstitial cells; after transplantation, its expression also became more predominant in the ovarian outer cortex, but this change was not as marked as in the case of VEGF. Because ovarian autotransplantation is followed by a rapid increase in serum gonadotropin levels, experiments were conducted to determine the importance of this rise in the activation of VEGF and TGF beta 1 gene expression. After transplantation, some animals were treated with the LHRH antagonist Nal-Glu LHRH (50 micrograms/rat, once a day for 2 days) to prevent the posttransplantation rise in serum gonadotropins. Quantitation of VEGF and TGF beta 1 mRNA by RNase protection assay 48 h later showed that suppression of gonadotropin secretion diminished the increase in both VEGF and TGF beta 1 gene expression. Concomitant treatment with PMSG (8 IU/rat, single injection), which mainly bypasses the suppression of endogenous FSH levels, restored the TGF beta 1 mRNA response, but had no effect on VEGF mRNA. The results suggest that the increase in gonadotropin secretion following ovarian transplantation contributes to revascularization of the graft by up-regulating the gene expression of two major angiogenic factors.     

Expression of epidermal growth factors and epidermal growth factor receptor in normal cycling human ovaries

Immunolocalization of transforming growth factor-alpha (TGF alpha), epidermal growth factor (EGF), cripto-1, amphiregulin and epidermal growth factor receptor (EGFR) was studied in 51 premenopausal human ovaries at various phases of the menstrual cycle. Localization of mRNA for TGF alpha and EGF was also studied by in-situ hybridization. Immunoreactive TGF alpha was observed predominantly in theca cells in 12 of 33 antral follicles in the follicular phase (6/14 dominant follicles, and 6/19 non-dominant) but not in any of the 18 follicles in the luteal phase or in primordial and pre-antral follicles. TGF alpha immunoreactivity was present predominantly in the luteinized granulosa cells in 13 of 15 corpora lutea in the luteal phase, which are considered to be active in steroidogenesis, but not in any of the regressed corpora lutea. Accumulation of TGF alpha mRNA hybridization signal was observed only in the theca cells in the follicles and luteinized theca cells in the ovaries that were immunohistochemically positive for TGF alpha. EGFR immunoreactivity was detected in 24 of 33 antral follicles in the follicular phase and in two of 18 follicles in the luteal phase but not in any of the corpora lutea. Immunoreactive EGF, cripto-1 and amphiregulin or EGF mRNA was not detected in any follicles, corpora lutea, or the stroma cells examined. These results indicate that, of the epidermal growth factors examined in this study, TGF alpha is locally synthesized in normal cycling human ovaries and TGF alpha may be synthesized in theca cells and act on the granulosa cells in a paracrine fashion through the EGFR in ovarian follicles.     

Interleukin-17

The particular interest of IL-17, a homodimeric cytokine of about 32 kDa, is the strict requirement for an activation signal to induce its expression from a rather restricted set of cells, human memory T cells or mouse alpha beta TCR+CD4-CD8- thymocytes. In contrast with the tightly controlled expression pattern of this gene, the IL-17 receptor, a novel cytokine receptor, is ubiquitously distributed but apparently more abundant in spleen and kidney. In addition to its capture by the T lymphotropic Herpesvirus Saimiri (HVS), this cytokine is inducing the secretion of IL-6, IL-8, PGE2, MCP-1 and G-CSF by adherent cells like fibroblasts, keratinocytes, epithelial and endothelial cells. IL-17 is also able to induce ICAM-1 surface expression, proliferation of T cells, and growth and differentiation of CD34+ human progenitors into neutrophils when cocultured in presence of irradiated fibroblasts. In vitro, IL-17 synergizes with other proinflammatory signals like TNF alpha for GM-CSF induction, and with CD40-ligand for IL-6, IL-8, RANTES and MCP-1 secretion from kidney epithelial cells. In vivo, injection of IL-17 induces a neutrophilia, except in IL-6-KO mice. The involvement of IL-17 in rejection of kidney graft has also been demonstrated. The role of this T cell secreted factor in various inflammatory processes is presently investigated.     

Electrocardiographic manifestations of dual atrioventricular node conduction during sinus rhythm

In search of critical genes associated with the mechanism of transforming growth factor-alpha (TGF alpha) action in human ovarian cancer, it was found that TGF alpha stimulates c-myc gene expression in human ovarian NIH:OVCAR-3. The role of c-myc in TGF alpha-stimulated growth of NIH:OVCAR-3 cells was examined by the use of the synthetic antisense-myc phosphorothioate oligonucleotide (OPT). Prior exposure of NIH:OVCAR-3 cells to an antisense-myc OPT inhibited TGF alpha-stimulated cell growth and DNA synthesis in a dose-dependent and sequence-specific manner over 4 days. c-Myc protein expression was down-regulated in the antisense-myc treated cells. These results demonstrate both the specific and durable effects of the antisense-myc OPT. Furthermore, the results suggest a role for c-myc in TGF alpha-stimulated cell proliferation.     

Individual cell analysis of the cytokine repertoire in human immunodeficiency virus-1-infected monocytes/macrophages by a combination of immunocytochemistry and in situ hybridization

The expression of many cytokines is dysregulated in individuals infected with the human immunodeficiency virus-1 (HIV-1). To determine the effects of HIV-1 infection on cytokine expression in individual cells (at the single cell level), we investigated the intracellular levels of proinflammatory cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, and IL-8) and hematopoietic growth factors (granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage colony-stimulating factor [GM-CSF]) in monocyte-derived macrophages, mock-infected, or infected with HIV-1 by immunocytochemical staining for cytokine protein and compared this with secreted cytokine levels as determined by specific enzyme-linked immunosorbent assay (ELISA). No difference in the frequency or intensity of cell-associated immunocytochemical cytokine staining could be observed between HIV-1 and mock-infected cells even though the level of secreted proinflammatory cytokines increased and the hematopoietic growth factors decreased in HIV-1-infected cultures. Furthermore, equal expression of cytokine mRNA was observed in all cells in the culture regardless of whether the cells were productively infected with HIV-1 as determined by double-labelling immunocytochemical staining for HIV-1 p24 antigen and in situ hybridization for cytokine mRNA expression. These results indicate that HIV-1 infection results in dysregulation of intracellular cytokine mRNA expression and cytokine secretion not only in HIV-1-infected cells, but also through an indirect way(s) affecting cells not producing virus.     

Pharmacokinetics and pharmacodynamics of candesartan after administration of its pro-drug candesartan cilexetil in patients with mild to moderate essential hypertension--a population analysis

Among the peptide growth factors active in breast glandular cell proliferation epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) are thought to play a major role in tumour development. They operate through binding to and activation of a common membrane receptor, defined as EGF-R. Their production is modulated by hormones and local growth factors. After it was shown by previous investigation in this laboratory that EGF-R could be detected in 90% of the tumours, but was masked by endogenous ligand in 36% of them, the question was raised as to the level of the ligand's expression in tumour tissue biopsies. Therefore, we investigated the expression of EGF and TGF alpha mRNA in 146 breast cancer biopsies by slot blot analysis using specific 32P-labelled probes. The data were correlated with sex steroids and EGF receptor content. Our results showed that EGF and TGF alpha coexisted in all tumour samples, and that their level of mRNA expression was similar in half of the tumours. Northern blot and polymerase chain reaction (PCR) analysis validated these findings. A significant direct correlation was found between the level of TGF alpha/EGF mRNA expression and the ER/progesterone receptor (PGR) content. TGF alpha and EGF mRNA levels were significantly higher in ER+ (P = 0.0015 and P = 0.0001, respectively) and in PGR+ tumours (P < 0.005 and P = 0.0001) than in their negative counterparts. Moreover, TGF alpha mRNA expression negatively correlated with the number of EGF-R binding sites measured by the standard method (P = 0.02), and it was significantly related to the number of sites occupied by endogenous ligand. In conclusion, it was shown that TGF alpha and EGF mRNA were coexpressed in all the tumour biopsies tested and that their level was higher in the hormone receptor positive than in negative samples. The correlation between the presence of ER/PGR sites, high level of TGF alpha/EGF mRNA and EGF-R occupancy by endogenous ligand is in favour of ER mediated control of TGF alpha and EGF production.     

Use of bifemelane hydrochloride in improving and maintaining the visual field of patients with glaucoma

Recently we demonstrated a large induction of activin expression in fibroblasts and keratinocytes after cutaneous injury in mice. To identify possible mediators of activin induction during skin repair, we have now analyzed the regulation of this factor in cultured keratinocytes and fibroblasts. Here we show that activin A mRNA and protein levels are low in quiescent keratinocytes and fibroblasts but expression is strongly induced upon serum treatment. The stimulatory effect of serum on activin expression is likely to be a combinatorial effect of different growth factors, since platelet-poor plasma serum and several purified serum growth factors also stimulated activin expression, although to a lesser extent than complete serum. Furthermore, we found increased expression of activin in keratinocytes and fibroblasts after addition of the proinflammatory cytokines interleukin 1beta and tumor necrosis factor alpha. Taken together, our data suggest that serum growth factors which are released upon hemorrhage as well as proinflammatory cytokines derived from neutrophils and macrophages might be responsible for induction of activin expression after injury.     

Plasminogen activator inhibitor-1 regulation in cultured rat peritubular cells by basic fibroblast growth factor and transforming growth factor-alpha

In the present study we examined the in vitro regulation of plasminogen activator inhibitor I (PAI-1) expression in peritubular cells recovered from 20-day-old rat testes. We tested two growth factors, basic fibroblast growth factor (bFGF) and transforming growth factor-alpha (TGF alpha). They are synthesized by Sertoli cells, and peritubular cells exhibit the corresponding high affinity receptors. After exposure to bFGF or TGF alpha (0.1-30 ng/ml), PAI-1 messenger RNA levels, as determined by Northern hybridization analysis, increased in a dose-dependent manner. The first significant effects were noted after 2-h exposure to bFGF or TGF alpha (10 ng/ml), and PAI-1 messenger RNA levels were maximally stimulated approximately 12-fold (bFGF) and 8-fold (TGF alpha) after 4 h. The two growth factors increased the amount of immunoreactive (Western blots) and biologically active (Stachrom) PAI-1 measured in the culture medium. Actinomycin D inhibited the effects of these factors, whereas cycloheximide augmented them. Phorbol myristate acetate, an activator of protein kinase C, mimicked the effects of bFGF and TGF alpha. Interestingly, long term (24-h) pretreatment with phorbol myristate acetate resulted in a severe loss of responsiveness to bFGF or TGF alpha. Staurosporine, an inhibitor of protein kinase C, also significantly reduced the effects of bFGF and TGF alpha. Given that PAI-1 inhibits Sertoli cell plasminogen activator activity and that bFGF and TGF alpha are synthesized by Sertoli cells, these factors are likely to interact to regulate protease activity in localized regions of the seminiferous tubule.     

Overexpression of a human transforming growth factor-alpha (TGF alpha) transgene reveals a dual antagonistic role of TGF alpha in female sexual development

The importance of transforming growth factor-alpha (TGF alpha) in female reproductive development was assessed using transgenic mice bearing a human TGF alpha complementary DNA under the control of a mouse metallothionein-1 promoter (MT1-hTGF alpha). Examination of the brain and ovaries 5 h after a single sc injection of zinc chloride, administered to activate the MT1-hTGF alpha transgene, revealed that prominent sites of human TGF alpha messenger RNA expression within these tissues were the hypothalamus and ovarian follicles, respectively. In vitro experiments showed that acute transgene activation increased hypothalamic release of LH-releasing hormone. In contrast, the ovarian steroidal response to gonadotropins, examined in vitro, was markedly attenuated. Chronic activation of transgene expression by daily administration of zinc chloride delayed the time of first estrus (an index of peripubertal estrogen secretion), but shortened the interval between first estrus and the onset of estrous cyclicity (an index of reproductive competence). Accumulation of small antral follicles, accompanied by thecal hypertrophy and enhanced androgen production, preceded the acquisition of ovulatory capacity. These changes were accompanied by reduced serum LH levels, suggesting that the relative inability of small antral follicles to develop further in TGF alpha-overexpressing mice is at least in part due to inappropriate gonadotropin support. Serum LH levels in these animals may be reduced by an augmented androgen negative feedback signal. Nontransgenic mouse ovaries, placed under the control of a transgenic hypothalamus by heterologous grafting, rapidly ovulated and initiated estrous cyclicity. In contrast, acquisition of reproductive capacity was severely delayed in nontransgenic mice bearing transgenic ovarian grafts. The results indicate that TGF alpha regulates female reproductive development through two opposing mechanisms: within the brain, it facilitates the neuroendocrine activation of the process; at the ovarian level, modulates the stimulatory effect of gonadotropin hormones on follicular growth and steroidogenesis.     

Tumour-derived, endocrine, exogenous and therapeutic factors differentially modulate cytokine secretion in whole blood cell culture

Following our previous results which showed that TGF-beta 1 suppressed the secretion of certain cytokines, we investigated the effects of different endogenous and exogenous factors on cytokine secretion in whole blood cell culture by using an enzyme-linked immunosorbent assay (ELISA) for measurement of cytokine concentrations. Several molecules including dexamethasone, noradrenaline (NA) and ethanol differentially inhibited mitogen-induced cytokine secretion. Dexamethasone and noradrenaline suppressed secretion of IL-2, IFN alpha, IFN gamma, TNF alpha, IL-1 alpha and IL-1 beta. beta-Endorphin and Leu-Enkephalin had no significant influence on cytokine secretion. Suppression of cytokine secretion by TGF-beta 1 was further intensified significantly and dose dependently by addition of noradrenaline. GM-CSF stimulated the secretion of IL-1 alpha, IL-1 beta and TNF gamma, but had no influence on the secretion of IL-2, IFN alpha and IFN gamma. G-CSF, IL-3 and SCF did not significantly influence secretion of all cytokines tested. Thus, endogenous and exogenous factors differentially influence cytokine secretion by immunocompetent cells.