Betamethasone, progesterone and RU-486 (mifepristone) exert similar effects on connexin expression in trophoblast-derived HTR-8/SVneo cells

Analysis of connexin 43, connexin 45 and N-cadherin in the human sertoli cell line FS1 and the human seminoma-like cell line TCam-2 in comparison with human testicular biopsies

BACKGROUND

Germ cell tumors are relatively common in young men. They derive from a non-invasive precursor, called germ cell neoplasia in situ, but the exact pathogenesis is still unknown. Thus, further understanding provides the basis for diagnostics, prognostics and therapy and is therefore paramount. A recently developed cell culture model consisting of human FS1 Sertoli cells and human TCam-2 seminoma-like cells offers new opportunities for research on seminoma. Since junctional proteins within the seminiferous epithelium are involved in cell organization, differentiation and proliferation, they represent interesting candidates for investigations on intercellular adhesion and communication in context with neoplastic progression.

METHODS

FS1 and TCam-2 cells were characterized regarding gap-junction-related connexin 43 (Cx43) and connexin 45 (Cx45), and adherens-junction-related N-cadherin using microarray, PCR, Western blot, immunocytochemistry and immunofluorescence. Results were compared to human testicular biopsies at different stages of seminoma development via immunohistochemistry to confirm the cell lines' representativeness. Furthermore, dye-transfer measurements were performed to investigate functional cell coupling.

RESULTS

Cx43, Cx45 and N-cadherin mRNA and protein were generally detectable in both cell lines via qualitative RT-PCR and Western blot. Immunocytochemistry and immunofluorescence revealed a mainly membrane-associated expression of N-cadherin in both cell lines, but gene expression values were higher in FS1 cells. Cx43 expression was also membrane-associated in FS1 cells but barely detectable in TCam-2 cells. Accordingly, a high gene expression value of Cx43 was measured for FS1 and a low value for TCam-2 cells. Cx45 was primary located in the cytoplasm of FS1 and TCam-2 cells and revealed similar low to medium gene expression values in both cell lines. Overall, results were comparable with corresponding biopsies. Additionally, both FS1 and TCam-2 cells showed dye diffusion into neighboring cells.

CONCLUSION

The junctional proteins Cx43, Cx45 and N-cadherin are expressed in FS1 and TCam-2 cells at mRNA and/or protein level in different amounts and localizations, and cells of both lines are functionally coupled among each other. Concerning the expression of these junctional proteins, FS1 and TCam-2 cells are largely representative for Sertoli and seminoma cells, respectively. Thus, these results provide the basis for further coculture experiments evaluating the role of junctional proteins in context with seminoma progression.

Beneficial effect of simvastatin on human umbilical vein endothelial cells gap junctions induced by TNF-α

Although simvastatin has been shown to inhibit vascular permeability, which might be amplified via gap junction intercellular communication (GJIC), the underlying mechanism of action remains unclear. In the present study, we investigated the effects and mechanisms of simvastatin on endothelial cells GJIC. Specifically, human umbilical vein endothelial cells (HUVECs) were stimulated with TNF-α (10 ng/mL) alone or in combination with simvastatin (5 µM), and their effects on vascular endothelial cell GJIC tested via the scrape loading/dye transfer (SL/DT) assay. Next, we performed immunofluorescence, real-time PCR and western blot assays to analyze expression of Cx37, Cx40 and Cx43 in HUVECs. Results showed that GJIC activity in HUVECs was markedly elevated in HUVECs treated with TNF-α in combination with simvastatin. In addition, simvastatin treatment significantly upregulated expression of Cx37 and Cx40 but downregulated Cx43 mRNAs and proteins. Taken together, these marked changes indicated that simvastatin exerts its regulatory effects on gap junction function by upregulating Cx37 and Cx40 and downregulating Cx43 expression.

Keratinocytes oxidative damage mechanisms related to airbone particle matter exposure

Epidemiological evidences have correlated airbone particulate matter (PM) to adverse health effects, mainly linking to pulmonary and cardiovascular disease. Nevertheless, only recently, some studies reported detrimental effects of PM on other organs such as skin. In a recent work, we have reported increased oxidative and inflammatory responses in Reconstituted Human Epidermis (RHE) exposed to ambient particles (CAPs) and we also demonstrated the ability of CAPs to penetrate the skin tissue. The present study was aimed to better understand the cellular mechanisms beyond the oxidative changes induced by CAPs (5-10-25μg/mL) in human immortalized keratinocytes (HaCaT). After 24h of treatment, CAPs were able to enter the cells leading to a decrease in viability, increased levels of 4-hydroxinonenal products (4-HNE) and IL-1α release. Overall these data, suggest lipid and protein oxidative damage, as well as an increase of inflammatory response after being challenged with CAPs. In addition, 3h after CAPs exposure we found a significant increase in NF-kB and Nrf2 translocation into the nucleus. In contrast, no differences in gene expression and enzymatic activity of Nrf2 target genes were detected. This last finding could be explained by the ability of CAPs to possibly alter the binding of Nrf2 to the ARE DNA sequence.

Vitamin C Compound Mixtures Prevent Ozone-Induced Oxidative Damage in Human Keratinocytes as Initial Assessment of Pollution Protection

Introduction

One of the main functions of cutaneous tissues is to protect our body from the outdoor insults. Ozone (O₃) is among the most toxic stressors to which we are continuously exposed and because of its critical location, the skin is one of the most susceptible tissues to the oxidative damaging effect of O₃. O₃ is not able to penetrate the skin, and although it is not a radical per se, the damage is mainly a consequence of its ability to induce oxidative stress via the formation of lipid peroxidation products.

Aim of Study

In this study we investigated the protective effect of defined “antioxidant” mixtures against O₃ induced oxidative stress damage in human keratinocytes and understand their underlying mechanism of action.

Results

Results showed that the mixtures tested were able to protect human keratinocytes from O₃-induced cytotoxicity, inhibition of cellular proliferation, decrease the formation of HNE protein adducts, ROS, and carbonyls levels. Furthermore, we have observed the decreased activation of the redox sensitive transcription factor NF-kB, which is involved in transcribing pro-inflammatory cytokines and therefore constitutes one of the main players associated with O₃ induced skin inflammation. Cells exposed to O₃ demonstrated a dose dependent increase in p65 subunit nuclear expression as a marker of NF-kB activation, while pre-treatment with the mixtures abolished NF-kB nuclear translocation. In addition, a significant activation of Nrf2 in keratinocytes treated with the mixtures was also observed.

Conclusion

Overall this study was able to demonstrate a protective effect of the tested compounds versus O_3-induced cell damage in human keratinocytes. Pre-treatment with the tested compounds significantly reduced the oxidative damage induced by O₃ exposure and this protective effect was correlated to the abolishment of NF-kB nuclear translocation, as well as activation of Nrf2 nuclear translocation activating the downstream defence enzymes involved in cellular detoxification process.

Progesterone is essential for protecting against LPS-induced pregnancy loss. LIF as a potential mediator of the anti-inflammatory effect of progesterone

Lipopolysaccharide (LPS) administration to mice on day 7 of gestation led to 100% embryonic resorption after 24 h. In this model, nitric oxide is fundamental for the resorption process. Progesterone may be responsible, at least in part, for a Th2 switch in the feto-maternal interface, inducing active immune tolerance against fetal antigens. Th2 cells promote the development of T cells, producing leukemia inhibitory factor (LIF), which seems to be important due to its immunomodulatory action during early pregnancy. Our aim was to evaluate the involvement of progesterone in the mechanism of LPS-induced embryonic resorption, and whether LIF can mediate hormonal action. Using in vivo and in vitro models, we provide evidence that circulating progesterone is an important component of the process by which infection causes embryonic resorption in mice. Also, LIF seems to be a mediator of the progesterone effect under inflammatory conditions. We found that serum progesterone fell to very low levels after 24 h of LPS exposure. Moreover, progesterone supplementation prevented embryonic resorption and LPS-induced increase of uterine nitric oxide levels in vivo. Results show that LPS diminished the expression of the nuclear progesterone receptor in the uterus after 6 and 12 h of treatment. We investigated the expression of LIF in uterine tissue from pregnant mice and found that progesterone up-regulates LIF mRNA expression in vitro. We observed that LIF was able to modulate the levels of nitric oxide induced by LPS in vitro, suggesting that it could be a potential mediator of the inflammatory action of progesterone. Our observations support the view that progesterone plays a critical role in a successful pregnancy as an anti-inflammatory agent, and that it could have possible therapeutic applications in the prevention of early reproductive failure associated with inflammatory disorders.

Glucocorticoid receptor signaling contributes to constitutive activation of the noncanonical NF-κB pathway in term human placenta

Our recent study demonstrated that constitutively activated RelB/NF-κB2 positively regulates the CRH in the human placenta. In the current study, we explored the role of the glucocorticoid receptor (GR) signaling in constitutive activation of the noncanonical NF-κB pathway. A glucocorticoid response element (GRE) motif search suggests that both NF-κB inducing kinase (NIK) and RelB genes, which are key regulators of the noncanonical NF-κB pathway, have a putative GRE within their promoter, approximately 1 kb upstream from the transcription start site. By using chromatin immunoprecipitation assay we identified that the GR and phosphorylated GR at Ser211 were associated with the GREs of both NIK and RelB. Dexamethasone stimulated expression of NIK, RelB, NF-κB2 as well as CRH and cyclooxygenase-2 (COX-2). Repression of GR by short interfering RNA resulted in inhibition of NIK, RelB, NF-κB2, CRH, and COX-2. In addition, depletion of GR attenuated glucocorticoid-mediated up-regulation of NIK, RelB, NF-κB2, CRH, and COX-2. Furthermore, siRNA specifically targeting NIK down-regulated CRH and COX-2. Taken together, these results suggest that constitutive activation of the noncanonical NF-κB pathway in term human placenta is driven by the GR signaling, which in turn up-regulates placental CRH and other NF-κB-responsive genes.