Exploring the expression and potential function of follicle stimulating hormone receptor in extragonadal cells related to abdominal aortic aneurysm

INTRODUCTION

Follicle stimulating hormone (FSH) is identified to play a role in postmenopausal disease and hypothesized to affect abdominal aortic aneurysm (AAA) onset/progression in postmenopausal women. We aimed to detect FSHR gene expression in AAA tissue and cell types involved in AAA formation.

METHODS

FSH stimulation of human umbilical cord endothelial cells (HUVECs), smooth muscle cells (HUCs) and PMA-differentiated macrophages to assess gene expression of FSHR and various markers. Human macrophages activated with various stimuli were assessed for FSHR gene expression. AAA dataset, AAA tissue samples and AAA-derived smooth muscle cells (SMC) obtained from elderly female donors were assessed for FSHR gene expression. AAA-SMCs were stimulated with FSH to assess its effect on gene expression. Lastly, oxidized low-density-lipoprotein (ox-LDL) uptake and abundance of cell surface protein markers were assessed by flow cytometry after FSH stimulation of human monocytes.

RESULTS

FSH stimulation showed similar levels of gene expression in HUVECs and HUCs. Only ACTA2 was downregulated in HUCs. In PMA-differentiated macrophages, gene expression of inflammation markers was unchanged after FSH stimulation. FSHR gene expression was found to be low in the AAA datasets. Female AAA-SMCs show occasional FSHR gene expression at a very low level, yet stimulation with FSH did not affect gene expression of SMC- or inflammation markers. FSH stimulation did not impact ox-LDL uptake or alter cell surface protein expression in monocytes. While FSHR gene expression was detected in human testis tissue, it was below quantification level in all other investigated cell types, even upon activation of macrophages with various stimuli.

CONCLUSION

Despite previous reports, we did not detect FSHR gene expression in various extragonadal cell types, except in occasional female AAA-SMCs. No clear effect on cell activation was observed upon FSH stimulation in any cell type. Our data suggest that a direct effect of FSH in AAA-related extragonadal cells is unlikely to influence AAA.

The role of plasminogen activator inhibitor type 1 in the inflammatory response to local tissue injury

BACKGROUND

The plasma levels of the plasminogen activator-inhibitor type 1 (PAI-1) are consistently elevated in patients with sterile tissue injury, often accompanied by a systemic acute phase protein response. It remains unknown, however, whether and to what extent PAI-1 affects the host response to trauma.

METHODS AND RESULTS

By using the well-established murine model of turpentine-induced tissue injury we compared local and systemic inflammatory responses in PAI-1 gene-deficient (PAI-1-/-) and normal wild-type (Wt) mice. Subcutaneous turpentine injection elicited strong increases in PAI-1 protein concentration in plasma and at the site of injury, but not in liver. PAI-1 mRNA was locally increased and expressed mainly by macrophages and endothelial cells. PAI-1 deficiency greatly enhanced the early influx of neutrophils to the site of inflammation, which was associated with increased edema and necrosis at 8 h after injection. Furthermore, PAI-1-/- mice showed a reduced early interleukin (IL)-6 induction with subsequently lower acute phase protein levels and a much slower recovery of body weight loss.

CONCLUSION

These findings suggest that PAI-1 is not merely a marker of tissue injury but plays a functional role in the local and systemic host response to trauma.

Transduction of the E6 and E7 genes of epidermodysplasia-verruciformis-associated human papillomaviruses alters human keratinocyte growth and differentiation in organotypic cultures

Epidermodysplasia-verruciformis-associated human papilloma virus DNA has been detected in skin cancers, in premalignant and benign skin lesions, and in plucked hairs from immunocompetent and immunosuppressed patients. The role of epidermodysplasia-verruciformis-associated human papilloma virus in the pathogenesis of nonmelanoma skin cancer is still enigmatic. In organotypic cultures we investigated the effects of retroviral transduction of the E6 and E7 genes of epidermodysplasia-verruciformis-associated human papilloma virus types 5, 12, 15, 17, 20, and 38 on the growth and differentiation of human keratinocytes. Differentiation was disturbed to different degrees as revealed by histology and by the expression patterns of differentiation markers keratin 10 and small proline rich protein 2. Conversely, proliferating cell nuclear antigen was induced in some of the suprabasal, differentiated cells to varying extent. No unscheduled DNA synthesis was detected in these cells, however, as probed by 5'-bromo-2'-deoxyuridine incorporation. Most intriguingly, when the E6 and E7 genes of epidermodysplasia-verruciformis-associated human papilloma virus types 15 and 17 were transduced, a broadening layer of basal cells and an accelerated differentiation were observed. In addition, "papilla-like structures" comprising basal-like keratinocytes arose from the basal layer into the differentiated layers. These cells did not express the differentiation markers keratin 10 and small proline rich protein 2, but did actively replicate DNA. These observations warrant further research by using this system to elucidate the replication strategy of epidermodysplasia-verruciformis-associated human papilloma virus types in keratinocytes and to shed light on the role of these human papilloma virus types in the pathogenesis of skin cancer.

Serial analysis of gene expression to assess the endothelial cell response to an atherogenic stimulus

Activation of human, arterial endothelial cells (ECs) is an early event in the pathogenesis of atherosclerosis. To identify the repertoire of genes that are differentially expressed after activation, we used serial analysis of gene expression (SAGE) to compare the mRNA spectrum of quiescent ECs with that of ECs activated for 6h with a strong atherogenic stimulus. SAGE methodology generates concatenated 'tags' of 10bp that are derived from a specific mRNA. About 5% of over 12000 tags analyzed is derived from genes that are differentially expressed (at least 5-fold up- or downregulated). These transcript tags are derived from only 56 genes, close to 1% of the total number of analyzed genes. Among these 56 differentially expressed genes are 42 known genes, including the hallmark endothelial cell activation markers interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1), plasminogen activator inhibitor 1 (PAI-1), Gro-alpha, Gro-beta and E-selectin. Differential transcription of a selection of the upregulated genes was confirmed by Northern blot analysis. A novel observation is the upregulation of activin betaA mRNA, a member of the transforming growth factor beta family. Apparent discrepancies between this novel technology and conventional methods are discussed. In conclusion, we demonstrate that for the application of SAGE, a moderate number of analyzed transcript tags suffices to reveal the significant alterations of EC transcription that results from a strong atherogenic stimulus.

Tissue distribution and regulation of murine von Willebrand factor gene expression in vivo

von Willebrand factor (vWF) is frequently used as a biochemical marker for endothelial cells (ECs). Despite this, little is known about the relative level of expression and regulation of this hemostatic factor in ECs in different vascular beds in vivo. In the present study, we used quantitative reverse transcription polymerase chain reaction and in situ hybridization analysis to study vWF gene expression in murine tissues. Large differences in the level of vWF mRNA were observed when comparing highly vascularized tissues, with the lung and brain containing 5 to 50 times higher concentrations of vWF mRNA than the kidney and liver. In this regard, ECs of small vessels and some microvessels in the lung and brain expressed abundant vWF mRNA, whereas ECs of similar sized vessels in the liver and kidney expressed relatively low levels. In general, significantly higher levels of vWF mRNA and antigen were demonstrated in ECs of larger vessels compared with microvessels and in venous ECs compared with arterial ECs. Although intraperitoneal administration of endotoxin (or tumor necrosis factor-alpha) increased plasma vWF levels, it had variable effects on the steady-state level of vWF mRNA in murine tissues (ie, it decreased vWF mRNA in many tissues, increased it in others, and had little effect on still others). These results indicate that vWF is differentially expressed and regulated in ECs present in different tissues and within the same vascular bed.

Lack of gradual regulation of tetracycline-controlled gene expression by the tetracyclin-repressor/VP16 transactivator (tTA) in cultured cells

Von Willebrand factor (vWF) is an essential multimeric protein for adhesion of platelets to an injured vessel wall. Endothelial cells secrete vWF by either a constitutive or a regulated pathway. It is unknown whether the secretory partitioning of vWF is dependent on the level of vWF synthesis. We employed the widely applied tetracycline-controlled transactivator system (tTA) to study the regulation of vWF mRNA synthesis in stably transfected Madin Darby kidney (MDCK-II) cells in a quantitative manner. Immunofluorescence staining with anti-vWF antibodies revealed that increasing the concentration of tetracycline resulted in a decreased number of MDCK-II cells that synthesize vWF. Apparently, tTA-regulated gene expression in an individual cell functions as an 'on/off' system rather than regulating the level of gene expression in a dose-response manner, as reported previously.