Estrogen attenuates integrin-beta(3)-dependent adventitial fibroblast migration after inhibition of osteopontin production in vascular smooth muscle cells

Osteopontin in Pulmonary Hypertension

Pulmonary hypertension (PH) is a pathological condition with multifactorial etiology, which is characterized by elevated pulmonary arterial pressure and pulmonary vascular remodeling. The underlying pathogenetic mechanisms remain poorly understood. Accumulating clinical evidence suggests that circulating osteopontin may serve as a biomarker of PH progression, severity, and prognosis, as well as an indicator of maladaptive right ventricular remodeling and dysfunction. Moreover, preclinical studies in rodent models have implicated osteopontin in PH pathogenesis. Osteopontin modulates a plethora of cellular processes within the pulmonary vasculature, including cell proliferation, migration, apoptosis, extracellular matrix synthesis, and inflammation via binding to various receptors such as integrins and CD44. In this article, we provide a comprehensive overview of the current understanding of osteopontin regulation and its impact on pulmonary vascular remodeling, as well as consider research issues required for the development of therapeutics targeting osteopontin as a potential strategy for the management of PH.

Cathepsin L was involved in vascular aging by mediating phenotypic transformation of vascular cells

Vascular media and adventitia-induced remodeling plays an important role in vascular aging. However, the mechanism remains unclear. This study aims to investigate the mechanisms underlying vascular aging. Transcriptome analysis revealed that the expression of cathepsin L (CTSL) significantly decreased in arteries of old mice (24 months old) compared with that in arteries of young mice (4 months old), which was confirmed by immunohistochemistry and Western blot. The expression of CTSL in adventitia fibroblasts (AFs) and vascular smooth muscle cells (VSMCs) of aged mice was lower than that of young mice. Compared with wild-type control mice, CTSL knockout (CTSL ^{- /-}) mice had increased collagen deposition (fibrosis) and decreased telomerase activity and LC3Ⅱ/ LC3Ⅰratio. The expression of mammalian target of rapamycin (mTOR) and osteopontin (OPN) increased in aortas of CTSL^-/-mice compared with that in aortas of wild-type control mice. In vitro, lentivirus-mediated CTSL knockdown induced VSMCs senescence and AFs transformed into myofibroblasts (MFs). Rapamycin, a mTOR inhibitor, inhibited CTSL deficiency induced VSMCs senescence, osteopontin (OPN) secretion and AFs migration. In conclusion, the decreased level of CTSL with age may participate in vascular aging by promoting the phenotypic transformation of vascular cells.

RAGE Differentially Altered in vitro Responses in Vascular Smooth Muscle Cells and Adventitial Fibroblasts in Diabetes-Induced Vascular Calcification

The Advanced Glycation End-Products (AGE)/Receptor for AGEs (RAGE) signaling pathway exacerbates diabetes-mediated vascular calcification (VC) in vascular smooth muscle cells (VSMCs). Other cell types are involved in VC, such as adventitial fibroblasts (AFBs). We hope to elucidate some of the mechanisms responsible for differential signaling in diabetes-mediated VC with this work. This work utilizes RAGE knockout animals and in vitro calcification to measure calcification and protein responses. Our calcification data revealed that VSMCs calcification was AGE/RAGE dependent, yet AFBs calcification was not an AGE-mediated RAGE response. Protein expression data showed VSMCs lost their phenotype marker, α-smooth muscle actin, and had a higher RAGE expression over non-diabetics. RAGE knockout (RKO) VSMCs did not show changes in phenotype markers. P38 MAPK, a downstream RAGE-associated signaling molecule, had significantly increased activation with calcification in both diabetic and diabetic RKO VSMCs. AFBs showed a loss in myofibroblast marker, α-SMA, due to calcification treatment. RAGE expression decreased in calcified diabetic AFBs, and P38 MAPK activation significantly increased in diabetic and diabetic RKO AFBs. These findings point to potentially an alternate receptor mediating the calcification response in the absence of RAGE. Overall, VSMCs and AFBs respond differently to calcification and the application of AGEs.

SPP1 derived from silica-exposed macrophage exosomes triggers fibroblast transdifferentiation

The occurrence and development of silicosis is related to the interaction of multiple cells through signal transmission caused by silica dust. Including inflammatory changes reduced by macrophages and phenotypic transdifferentiation reduced by lung fibroblasts. As a communication medium between cells, exosomes have become a hot research topic. To explore the role of exosomal proteins in the occurrence and development of silicosis and the possible intervention targets, this study conducted proteomic analysis of macrophage-derived exosomes induced by silica, to identify specific proteins for intervention. In this study, we used proteomic analysis to screen exosomal protein profiles from the RAW264.7 macrophages exposed to silica. A total of 291 proteins were differentially expressed, of which 178 were upregulated and 113 were downregulated. By performing functional annotation and analysis of the differentially expressed proteins, we identified proteins SPP1, HMGB3, and HNRNPAB, which were consistent with the proteomics analysis. The involvement of SPP1 protein in fibrosis was studied further. Knocking down the expression of SPP1 in exosomes resulted in a decrease in fibrosis-related indicators. These results help to understand that exosomal protein can mediate cell communication and play a key role in the transition from fibroblasts to myofibroblasts. Further, this study also provided strategies and scientific basis for future studies on the intervention of silicosis.

Quantification of uncertainty in a new network model of pulmonary arterial adventitial fibroblast pro-fibrotic signalling

Here, we present a novel network model of the pulmonary arterial adventitial fibroblast (PAAF) that represents seven signalling pathways, confirmed to be important in pulmonary arterial fibrosis, as 92 reactions and 64 state variables. Without optimizing parameters, the model correctly predicted 80% of 39 results of input-output and inhibition experiments reported in 20 independent papers not used to formulate the original network. Parameter uncertainty quantification (UQ) showed that this measure of model accuracy is robust to changes in input weights and half-maximal activation levels (EC50), but is more affected by uncertainty in the Hill coefficient (n), which governs the biochemical cooperativity or steepness of the sigmoidal activation function of each state variable. Epistemic uncertainty in model structure, due to the reliance of some network components and interactions on experiments using non-PAAF cell types, suggested that this source of uncertainty had a smaller impact on model accuracy than the alternative of reducing the network to only those interactions reported in PAAFs. UQ highlighted model parameters that can be optimized to improve prediction accuracy and network modules where there is the greatest need for new experiments. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Sex-related differences in contemporary biomarkers for heart failure: a review

The use of circulating biomarkers for heart failure (HF) is engrained in contemporary cardiovascular practice and provides objective information about various pathophysiological pathways associated with HF syndrome. However, biomarker profiles differ considerably among women and men. For instance, in the general population, markers of cardiac stretch (natriuretic peptides) and fibrosis (galectin‐3) are higher in women, whereas markers of cardiac injury (cardiac troponins) and inflammation (sST2) are higher in men. Such differences may reflect sex‐specific pathogenic processes associated with HF risk, but may also arise as a result of differences in sex hormone profiles and fat distribution. From a clinical perspective, sex‐related differences in biomarker levels may affect the objectivity of biomarkers in HF management because what is considered to be ‘normal’ in one sex may not be so in the other. The objectives of this review are, therefore: (i) to examine the sex‐specific dynamics of clinically relevant HF biomarkers in the general population, as well as in HF patients; (ii) to discuss the overlap between sex‐related and obesity‐related effects, and (iii) to identify knowledge gaps to stimulate research on sex‐related differences in HF.

Coronary Microvascular Dysfunction and Estrogen Receptor Signaling

Chest pain with non-obstructive coronary artery disease (NOCAD) occurs more frequently in women than in men and is mainly related to coronary microvascular disease (CMD). The majority of CMD patients are postmenopausal women, suggesting a role for lack of estrogens in the development and progression of CMD. Patients are often discharged without a clear treatment plan due to the limited understanding of etiology and diagnostic parameters of CMD and have significantly higher rates of future cardiovascular events. Thus, there is a need for a better understanding of the underlying biology, and CMD-specific diagnostic tests and therapies. In this article, we reviewed recent studies on CMD, estrogen action in coronary microvasculature, and diagnosis and treatment options for CMD in postmenopausal women.

Induced Pluripotent Stem Cell-Derived Endothelial Cells Overexpressing Interleukin-8 Receptors A/B and/or C-C Chemokine Receptors 2/5 Inhibit Vascular Injury Response

Recruitment of neutrophils and monocytes/macrophages to the site of vascular injury is mediated by binding of chemoattractants to interleukin (IL) 8 receptors RA and RB (IL8RA/B) C‐C chemokine receptors (CCR) 2 and 5 expressed on neutrophil and monocyte/macrophage membranes. Endothelial cells (ECs) derived from rat‐induced pluripotent stem cells (RiPS) were transduced with adenovirus containing cDNA of IL8RA/B and/or CCR2/5. We hypothesized that RiPS‐ECs overexpressing IL8RA/B (RiPS‐IL8RA/B‐ECs), CCR2/5 (RiPS‐CCR2/5‐ECs), or both receptors (RiPS‐IL8RA/B+CCR2/5‐ECs) will inhibit inflammatory responses and neointima formation in balloon‐injured rat carotid artery. Twelve‐week‐old male Sprague‐Dawley rats underwent balloon injury of the right carotid artery and intravenous infusion of (a) saline vehicle, (b) control RiPS‐Null‐ECs (ECs transduced with empty virus), (c) RiPS‐IL8RA/B‐ECs, (d) RiPS‐CCR2/5‐ECs, or (e) RiPS‐IL8RA/B+CCR2/5‐ECs. Inflammatory mediator expression and leukocyte infiltration were measured in injured and uninjured arteries at 24 hours postinjury by enzyme‐linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. Neointima formation was assessed at 14 days postinjury. RiPS‐ECs expressing the IL8RA/B or CCR2/5 homing device targeted the injured arteries and decreased injury‐induced inflammatory cytokine expression, neutrophil/macrophage infiltration, and neointima formation. Transfused RiPS‐ECs overexpressing IL8RA/B and/or CCR2/5 prevented inflammatory responses and neointima formation after vascular injury. Targeted delivery of iPS‐ECs with a homing device to inflammatory mediators in injured arteries provides a novel strategy for the treatment of cardiovascular diseases. Stem Cells Translational Medicine2017;6:1168–1177

Secreted Phosphoprotein 1 and Sex-Specific Differences in Silica-Induced Pulmonary Fibrosis in Mice

BACKGROUND

Fibrotic lung diseases occur predominantly in males, and reports describe better survival in affected females. Male mice are more sensitive to silica-induced lung fibrosis than silica-treated female mice. Secreted phosphoprotein 1 (SPP1, also known as osteopontin) increases in pulmonary fibrosis, and Spp1 transcription may be regulated by estrogen or estrogen receptor-related receptors.

OBJECTIVE

We determined whether differences in silica-induced SPP1 levels contribute to sex differences in lung fibrosis.

METHODS

Male and female mice were treated with 0.2 g/kg intratracheal silica, and lung injury was assessed 1, 3, or 14 days post-exposure. Gene-targeted (Spp1-/-) mice, control Spp1+/+ (C57BL/6J) mice, ovariectomized (OVX) female mice, and estrogen-treated male mice were treated with silica, and lung injury was assessed.

RESULTS

Silica-induced SPP1 in lung tissue, bronchoalveolar lavage, and serum increased more in male than in female mice. Following silica treatment, bronchoalveolar lavage cell infiltrates decreased in female Spp1-/- mice compared with female Spp1+/+ mice, and lung hydroxyproline decreased in male Spp1-/- mice compared with male Spp1+/+ mice. OVX female mice had increased lung SPP1 expression in response to silica compared with silica-treated sham female mice. Silica-induced lung collagen and hydroxyproline (markers of fibrosis), and SPP1 levels decreased in estrogen-treated males compared with untreated males.

CONCLUSION

These findings suggest that sex-specific differences in SPP1 levels contribute to the differential sensitivity of male and female mice to the development of silica-induced fibrosis.

CITATION

Latoche JD, Ufelle AC, Fazzi F, Ganguly K, Leikauf GD, Fattman CL. 2016. Secreted phosphoprotein 1 and sex-specific differences in silica-induced pulmonary fibrosis in mice. Environ Health Perspect 124:1199-1207; http://dx.doi.org/10.1289/ehp.1510335.

SIRT1 inhibits TNF-α-induced apoptosis of vascular adventitial fibroblasts partly through the deacetylation of FoxO1

Sirtuin 1 (SIRT1), a NAD(+)-dependent class III histone deacetylase, participates in regulating cellular apoptosis, senescence and metabolism by deacetylating histones and multiple transcription factors. In this study, we aimed to determine the effect of SIRT1 on the apoptosis of vascular adventitial fibroblasts (VAFs) and related signaling pathways. SIRT1 was found in the nucleus of VAFs and translocated into the cytoplasm in response to tumor necrosis factor-α (TNF-α). Moreover, SIRT1 protein expression was reduced in VAFs stimulated with TNF-α. In addition, TNF-α increased the apoptosis of VAFs. Activation of SIRT1 by resveratrol (RSV) or overexpression of SIRT1 attenuated TNF-α-induced VAF apoptosis by decreasing the percentage of apoptotic cells and cleaved caspase-3 protein expression and increasing the Bcl-2/Bax ratio. In contrast, inhibition of SIRT1 by sirtinol/nicotinamide or knockdown of SIRT1 enhanced apoptosis of VAFs. On the other hand, knockdown of FoxO1 reduced TNF-α-induced VAF apoptosis. SIRT1 interacted with FoxO1 in VAFs by the co-immunoprecipitation assay. Further study showed that RSV or SIRT1 overexpression decreased acetylated-FoxO1 (Ac-FoxO1) protein expression in VAFs stimulated with TNF-α. Knockdown of SIRT1 resulted in an increase in Ac-FoxO1 protein expression. Taken together, these findings indicate that SIRT1 inhibits the apoptosis of VAFs, whereas FoxO1 promotes VAF apoptosis. Furthermore, the inhibitory effect of SIRT1 on VAF apoptosis is partly mediated by the deacetylation of FoxO1.

Similarity of mouse perivascular and brown adipose tissues and their resistance to diet-induced inflammation

Thoracic perivascular adipose tissue (PVAT) is a unique adipose depot that likely influences vascular function and susceptibility to pathogenesis in obesity and the metabolic syndrome. Surprisingly, PVAT has been reported to share characteristics of both brown and white adipose, but a detailed direct comparison to interscapular brown adipose tissue (BAT) has not been performed. Here we show by full genome DNA microarray analysis that global gene expression profiles of PVAT are virtually identical to BAT, with equally high expression of Ucp-1, Cidea, and other genes known to be uniquely or very highly expressed in BAT. PVAT and BAT also displayed nearly identical phenotypes upon immunohistochemical analysis, and electron microscopy confirmed that PVAT contained multilocular lipid droplets and abundant mitochondria. Compared with white adipose tissue (WAT), PVAT and BAT from C57BL6/J mice fed a high-fat diet for 13 wk had markedly lower expression of immune cell-enriched mRNAs, suggesting resistance to obesity-induced inflammation. Indeed, staining of BAT and PVAT for macrophage markers (F4/80 and CD68) in obese mice showed virtually no macrophage infiltration, and FACS analysis of BAT confirmed the presence of very few CD11b(+)/CD11c(+) macrophages in BAT (1.0%) compared with WAT (31%). In summary, murine PVAT from the thoracic aorta is virtually identical to interscapular BAT, is resistant to diet-induced macrophage infiltration, and thus may play an important role in protecting the vascular bed from inflammatory stress.

Coronary Calcification and Hormones

The pathogenesis of coronary artery calcification and its role in atherogenesis has not been completely understood but is a new focus of interest in experimental and clinical research. Various bioactive substances, including hormones, have been implicated in the process of arterial calcification. This review considers the relationship between coronary artery calcification and hormones. These hormones may become therapeutic targets for the prevention of arterial calcification.

Sex-based differences in vascular function

Cardiovascular disease is the leading cause of morbidity and mortality for both men and women in the USA. However, there are differences between the sexes in age-dependent onset, severity, symptoms and outcomes. Basic research into the causes of sex-dependent differences in cardiovascular disease is ongoing and includes investigation into genetic variation in expression and distribution of receptors for the sex steroids; specificity of natural and synthetic ligands that activate the sex steroid receptors; and intracellular mechanisms that are activated by the receptors in all components of the vessel wall and blood elements, which integrate to regulate vascular tone, vascular repair and remodeling in health and disease. In this era of personalized medicine, basic research into mechanisms of sex differences in vascular function will result in improved prevention, detection and treatment of cardiovascular disease in both men and women.

Estrogen and mechanisms of vascular protection

Estrogen has antiinflammatory and vasoprotective effects when administered to young women or experimental animals that appear to be converted to proinflammatory and vasotoxic effects in older subjects, particularly those that have been hormone free for long periods. Clinical studies have raised many important questions about the vascular effects of estrogen that cannot easily be answered in human subjects. Here we review cellular/molecular mechanisms by which estrogen modulates injury-induced inflammation, growth factor expression, and oxidative stress in arteries and isolated vascular smooth muscle cells, with emphasis on the role of estrogen receptors and the nuclear factor-kappaB (NFkappaB) signaling pathway, as well as evidence that these protective mechanisms are lost in aging subjects.

Osteopontin promoter polymorphism is associated with increased carotid intima-media thickness

BACKGROUND

Osteopontin (OPN)-transgenic mice exhibit increased carotid artery intima-media thickness (CIMT), smooth muscle cell proliferation, and atheroma formation.

METHODS

An association of the human T-66G promoter variant with CIMT was examined in Caucasian adults grouped according to metabolic syndrome criteria: present (+MetS; n = 70) or absent (-MetS; n = 70).

RESULTS

The G-allele frequency was 22%. For the entire cohort, the G group (TG and GG) was associated with significantly lower age-adjusted and gender-adjusted CIMT compared with the TT group (P = .008); similar analysis by metabolic syndrome group found a significant difference only in the -MetS group (P = .018). Stepwise multivariate regression showed that after age and waist circumference, the T-66G variant was the next most predictive of CIMT (P = .007). These data suggest that in a normoglycemic environment, human vascular OPN gene expression contributes to arterial structure, an effect diminished in dysmetabolic states.

CONCLUSION

Humans with the OPN -66 TT genotype, particularly those without metabolic syndrome, exhibit thicker CIMT.

Osteopontin stimulates vascular smooth muscle cell migration by inducing FAK phosphorylation and ILK dephosphorylation

Focal adhesion kinase (FAK) and integrin-linked kinase (ILK) are both involved in integrin-mediated cell migration. However, the molecular mechanism, and the relationship between FAK and ILK activity in signaling transduction for the osteopontin (OPN)-induced migration of vascular smooth muscle cells (VSMCs) remain unclear. Here, we show that treating VSMCs with OPN could result in the dissociation of FAK with ILK by inducing phosphorylation of the former and dephosphorylation of the latter. Furthermore, we demonstrate that FAK phosphorylation induced by OPN is coupled with ILK dephosphorylation. We also provide evidence that ILK acts downstream of FAK in the signaling pathways that mediate OPN-induced VSMC migration. These findings suggest that FAK phosphorylation and ILK dephosphorylation play important roles in VSMC migration induced by OPN.

Calcium Deposition and Associated Chronic Diseases (Atherosclerosis, Diffuse Idiopathic Skeletal Hyperostosis, and Others)

Extracellular matrix mineralization or calcification occurs in many pathologic conditions, including atherosclerosis, medial wall calcification, diffuse idiopathic skeletal hyperostosis, and chondrocalcinosis. Vascular wall calcification is the most common and involves two mechanisms: passive calcification resulting from breakdown of the protection system and active calcification resulting from transdifferentiation of mesenchymal cells in the vascular wall to bone. Although reports are conflicting, several matrix proteins are identified as protective factors against dystrophic calcification in nonosseous tissues. Serum matrix Gla protein may be a marker of osteometabolic syndromes that cause hyperostosis and plays a role in Milwaukee shoulder syndrome.

Alternatively spliced FGFR-1 isoforms differentially modulate endothelial cell activation of c-YES

Ligand activation of fibroblast growth factor receptor-1 (FGFR-1) induces an angiogenic response following activation of multiple intracellular signaling substrates, including the Src family of nonreceptor tyrosine kinases (SFK). However, the direct association between FGFR-1 and SFK and the involvement of SFK in FGFR-1-dependent cell proliferation have been controversial. Structural variants of FGFR-1 are generated by alternative splicing which results in two major isoforms, containing either three (FGFR-1alpha) or two (FGFR-1beta) immunoglobulin-like domains in the extracellular region. To determine whether alternatively spliced FGFR-1 isoforms differentially activate SFK, we have examined FGF receptor-negative endothelial cells stably transfected with human cDNA encoding either FGFR-1alpha or FGFR-1beta. Transient activation of c-YES, the predominant SFK expressed in these endothelial cells, was restricted to FGFR-1beta transfectants following exposure to acidic fibroblast growth factor (FGF-1). Co-immunoprecipitation studies revealed that c-YES directly associated with FGFR-1beta. The Src homology (SH)2 domain (and not the SH3 domain) of c-YES was able to recognize tyrosine phosphorylated FGFR-1beta. FGFR-1beta-specific activation of c-YES was accompanied by its association with and activation of cortactin. FGF-1 treatment of both FGFR-1alpha and FGFR-1beta transfectants induced SFK-independent cellular proliferation and growth in low density cultures. At high density, under both anchorage-dependent and -independent conditions, FGF-1 failed to induce proliferation and growth of FGFR-1alpha transfectants. In contrast, FGF-1 induced proliferation, growth, and formation of cord-like structures in high density cultures of FGFR-1beta transfectants in an SFK-dependent manner. In vitro cord formation on Matrigel was restricted to FGFR-1beta transfectants in an SFK-dependent manner. Formation of vascular structures in vivo was limited to endothelial cells transfected with FGFR-1beta. Collectively, these results emphasize the roles of alternatively spliced FGFR-1 structural isoforms and activation of SFK as modulators of endothelial cell growth during the formation of neovascular structures.

Phosphatidylinositol-3-kinase signaling mediates vascular smooth muscle cell expression of periostin in vivo and in vitro

OBJECTIVE

Periostin is dramatically upregulated in rat carotid arteries after balloon injury. The objective of the present study was to understand mechanisms underlying periostin upregulation in balloon-injured rat carotid arteries and in cultured vascular smooth muscle cells (VSMCs).

METHODS AND RESULTS

Periostin protein was strongly expressed at 3 days (in the medial SMCs) and 7 days (in the neointima) after injury. It was also abundantly expressed in the neointima in the late phase (at 14 and 28 days) after injury. Periostin upregulation was mediated through PI-3-kinase-dependent signaling pathway. In vivo, wortmannin, a PI-3-kinase inhibitor, inhibited balloon injury-induced Akt phosphorylation and periostin mRNA expression. In vitro, periostin mRNA expression in cultured VSMCs was stimulated by growth factors (transforming growth factor-beta1 (TGF-beta1), fibroblast growth factors (FGFs), PDGF-BB, and angiotensin II). This stimulatory effect was inhibited by the PI-3-kinase inhibitor LY294002. Further, periostin protein was mostly located in the cytoplasma of VSMCs in culture and abundantly secreted into the culture medium (CM) after stimulation with FGF-2, which significantly promoted VSMC migration in vitro. Immunodepletion of periostin from the VSMC-CM or blockade of periostin function with an anti-periostin antibody significantly reduced VSMC migration.

CONCLUSIONS

Upregulation of periostin expression in rat carotid arteries following balloon injury and in cultured VSMCs after stimulation by growth factors is mediated through PI-3-kinase-dependent signaling pathway. Periostin protein secreted by VSMCs plays a significant role in regulating VSMC migration in vitro.

Correlation of osteopontin protein expression and pathological stage across a wide variety of tumor histologies

PURPOSE

Osteopontin (OPN) is an integrin-binding protein overexpressed in various experimental models of malignancy and appears to be involved in tumorigenesis and metastasis. Although various studies have assessed OPN protein levels in several tumor types, a broad survey of OPN expression in human neoplasia under the same experimental conditions has not been carried out.

EXPERIMENTAL DESIGN

We used immunohistochemistry to detect OPN in a selection of 350 human tumors and 113 normal tissues, from a variety of body sites, using stage-oriented human cancer tissue arrays. Tumors included malignancies from breast (26), ovary (22), endometrium (14), esophagus (10), stomach (11), pancreas (16), bile duct (1), liver (9), colon (20), kidney (53), bladder (33), prostate (28), head and neck (60), salivary glands (14), lung (17), skin (6), and brain (10).

RESULTS

High cytoplasmic OPN staining was observed in 100% of gastric carcinomas, 85% of colorectal carcinomas, 82% of transitional cell carcinomas of the renal pelvis, 81% of pancreatic carcinomas, 72% of renal cell carcinomas, 71% of lung and endometrial carcinomas, 70% of esophageal carcinomas, 58% of squamous cell carcinomas of the head and neck, and 59% of ovarian carcinomas. Although OPN expression was identified in a good number of bladder, prostate, and brain tumors, the majority of 6 skin cancers, 11 of 14 salivary gland cancers, 2 thyroid carcinomas, and 23 of 26 breast cancers revealed low OPN positivity or were negative. When considering all sites, OPN expression significantly correlated with tumor stage (Spearman's correlation coefficient, P = 0.0002). OPN score and stage were also significantly correlated for specific cancer sites including bladder (P = 0.01), colon (P = 0.004), kidney (P = 0.0001), larynx (P = 0.035), mouth (P = 0.046), and salivary gland (P = 0.011).

CONCLUSIONS

This study reports the broad distribution of OPN in human tumors from different body sites, suggesting involvement of this protein in tumor formation. The strong correlation between pathological stage and OPN across multiple tumor types suggests a role for OPN in tumor progression.

Osteogenic regulation of vascular calcification: an early perspective

Cardiovascular calcification is a common consequence of aging, diabetes, hypercholesterolemia, mechanically abnormal valve function, and chronic renal insufficiency. Although vascular calcification may appear to be a uniform response to vascular insult, it is a heterogenous disorder, with overlapping yet distinct mechanisms of initiation and progression. A minimum of four histoanatomic variants-atherosclerotic (fibrotic) calcification, cardiac valve calcification, medial artery calcification, and vascular calciphylaxis-arise in response to metabolic, mechanical, infectious, and inflammatory injuries. Common to the first three variants is a variable degree of vascular infiltration by T cells and macrophages. Once thought benign, the deleterious clinical consequences of calcific vasculopathy are now becoming clear; stroke, amputation, ischemic heart disease, and increased mortality are portended by the anatomy and extent of calcific vasculopathy. Along with dystrophic calcium deposition in dying cells and lipoprotein deposits, active endochondral and intramembranous (nonendochondral) ossification processes contribute to vascular calcium load. Thus vascular calcification is subject to regulation by osteotropic hormones and skeletal morphogens in addition to key inhibitors of passive tissue mineralization. In response to oxidized lipids, inflammation, and mechanical injury, the microvascular smooth muscle cell becomes activated. Orthotopically, proliferating stromal myofibroblasts provide osteoprogenitors for skeletal growth and fracture repair; however, in valves and arteries, vascular myofibroblasts contribute to cardiovascular ossification. Current data suggest that paracrine signals are provided by bone morphogenetic protein-2, Wnts, parathyroid hormone-related polypeptide, osteopontin, osteoprotegerin, and matrix Gla protein, all entrained to endocrine, metabolic, inflammatory, and mechanical cues. In end-stage renal disease, a "perfect storm" of vascular calcification often occurs, with hyperglycemia, hyperphosphatemia, hypercholesterolemia, hypertension, parathyroid hormone resistance, and iatrogenic calcitriol excess contributing to severe calcific vasculopathy. This brief review recounts emerging themes in the pathobiology of vascular calcification and highlights some fundamental deficiencies in our understanding of vascular endocrinology and metabolism that are immediately relevant to human health and health care.

Gender and cardiac surgery

The increased operative mortality and morbidity of women compared with men undergoing CABG surgery results from multiple differences in presentation, preoperative risk profile, and surgical factors. Investigators have found consistently that women present with a different preoperative risk profile than do men. Women more commonly have factors associated with increased short- and long-term mortality, such as less frequent use of IMA grafts. Differences in study design and patient population may contribute to variability in short- and long-term mortality among the various studies. The lack of representation of women in older clinical trials has hindered our understanding of the management of CAD in women; this situation must be remedied in future studies, [95]. Known physiologic and anatomic differences must be evaluated for their effects on outcomes. Further studies are needed to evaluate gender-related differences in autonomic responses to acute coronary occlusion, complications related to cardiopulmonary bypass, susceptibility to abnormalities in coagulation, and other factors that might account for discrepant outcomes in men versus women undergoing CABG [96]. Beyond these factors, specific pharmacologic and therapeutic considerations, such as the role of estrogen replacement therapy, need to be clarified. As further knowledge accumulates, it is hoped that gender-specific risk factors can be mitigated and protective factors exploited, thereby improving the outcomes for all cardiac surgery patients.

Alphavbeta3-integrin antagonists inhibit thrombin-induced proliferation and focal adhesion formation in smooth muscle cells

Alphavbeta3-integrin antagonists reduced neointimal formation following vascular injury in eight different animal models. Because alpha-thrombin contributes to neointimal formation, we examined the hypothesis that alphavbeta3-integrins influence alpha-thrombin-induced signaling. Cultured rat aortic smooth muscle cells (RASMC) expressed alphavbeta3-integrins as demonstrated by immunofluorescence microscopy and fluorescence-activated cell sorting analysis. Proliferative responses to alpha-thrombin were partially inhibited by anti-beta3-integrin monoclonal antibody F11 and by cyclic RGD peptides. Immunofluorescence microscopy showed that alpha-thrombin stimulated a rapid increase in the formation of focal adhesions as identified by vinculin staining and that this effect was partially inhibited by alphavbeta3 antagonists. Beta3-integrin staining was diffuse in quiescent RASMC and did not concentrate at sites of focal adhesions following thrombin treatment. Alpha-thrombin elicited a time-dependent increase in activation of c-Jun NH2-terminal kinase-1 (JNK1) and in tyrosine phosphorylation of focal adhesion kinase (FAK). Alphavbeta3-integrin antagonists partially inhibited increases in JNK1 activity but had no effect on FAK phosphorylation. In SMC isolated from beta3-integrin-deficient mice, focal adhesion formation was impaired in response to thrombin but not sphingosine-1-phosphate, a potent activator of Rho. In summary, alphavbeta3-integrins play an important role in alpha-thrombin-induced proliferation and focal adhesion formation in RASMC.

Alternatively spliced FGFR-1 isoform signaling differentially modulates endothelial cell responses to peroxynitrite

Mounting experimental evidence has suggested that the trophic environment of cells in culture is an important determinant of their vulnerability to the cytotoxic effects of reactive oxidants such as peroxynitrite (ONOO(-)). However, acidic fibroblast growth factor (FGF-1)-induced signaling renders some cells more sensitive and others resistant to the cytotoxic effects of ONOO(-). To determine whether alternatively spliced fibroblast growth factor receptor (FGFR-1) isoforms are responsible for this differential response, we have stably transfected FGFR-negative rat brain-derived resistant vessel endothelial cells (RVEC) with human cDNA sequences encoding either FGFR-1 alpha or FGFR-1 beta. FGF-1 treatment of RVEC(R-1 alpha) transfectants enhanced ONOO(-)-mediated cell death in a manner dependent upon FGFR-1 tyrosine kinase, MEK/Erk 1/2 kinase, and p38 MAP kinase activities and independent of Src-family kinase (SFK) activity. FGF-1 treatment of RVEC(R-1 beta) transfectants inhibited the cytotoxic effects of ONOO(-) in a manner dependent upon FGFR-1 tyrosine kinase, MEK/Erk 1/2 kinase, and SFK activities and independent of p38 MAP kinase activity. FGF-1-induced preactivation of both FGFR-1 tyrosine and Erk 1/2 kinases was detected in both RVEC(R-1 alpha) and RVEC(R-1 beta) transfectants. FGF-1-induced preactivation of p38 MAPK was restricted to RVEC(R-1 alpha) transfectants, whereas, ligand-induced preactivation of SFK was limited to RVEC(R-1 beta) transfectants. Collectively, these results both reemphasize the role of extracellular trophic factors and their receptor-mediated signaling pathways during cellular responses to oxidant stress and provide a first indication that the alternatively spliced FGFR-1 isoforms induce differential signal transduction pathways.

Hormone replacement therapy is associated with improved survival in women undergoing coronary artery bypass grafting

OBJECTIVES

The effect of hormone replacement therapy on cardiovascular events in postmenopausal women is controversial. We investigated the roles of sex and hormone replacement status in female patients undergoing coronary artery bypass grafting.

METHODS

We reviewed the records of 4259 consecutive patients aged 55 years or older who underwent primary elective isolated coronary artery bypass at our hospital between May 1996 and September 2001.

RESULTS

Female sex with hormone replacement therapy was an independent predictor of decreased mortality, regardless of age. Mortality was 6.7% (61/905) for women not receiving hormone replacement therapy, 2.3% (6/256) for hormone replacement therapy recipients, and 2.7% (82/3098) for men (P <.01 for all comparisons). Of the characteristics examined, multivariate analysis indicated that independent predictors of mortality were advanced age, previous congestive heart failure, class IV angina, and female sex without hormone replacement (P <.005). Independent predictors of survival included use of an internal thoracic artery graft and white ethnicity. There were no significant intergroup differences in the incidence of nonfatal, morbid postoperative events.

CONCLUSIONS

Postmenopausal women undergoing coronary artery bypass had a significantly improved in-hospital survival if they had been receiving hormone replacement therapy. The improved survival might be related to one or more of the numerous cardiovascular effects of estrogen that are considered beneficial. A prospective randomized trial is needed to validate the observation that hormone replacement therapy is protective in this setting.

Osteopontin transcription in aortic vascular smooth muscle cells is controlled by glucose-regulated upstream stimulatory factor and activator protein-1 activities

The expression of the matrix cytokine osteopontin (OPN) is up-regulated in aortic vascular smooth muscle cells (VSMCs) by diabetes. OPN expression in cultured VSMCs is reciprocally regulated by glucose and 2-deoxyglucose (2-DG; inhibitor of cellular glucose metabolism). Systematic analyses of OPN promoter-luciferase reporter constructs identify a CCTCATGAC motif at nucleotides -80 to -72 relative to the initiation site that supports OPN transcription in VSMCs. The region -83 to -45 encompassing this motif confers basal and glucose- and 2-DG-dependent transcription on an unresponsive promoter. Competition and gel mobility supershift assays identify upstream stimulatory factor (USF; USF1:USF2) and activator protein-1 (AP1; c-Fos:c-Jun) in complexes binding the composite CCTCATGAC element. Glucose up-regulates both AP1 and USF binding activities 2-fold in A7r5 cells and selectively up-regulates USF1 protein levels. By contrast, USF (but not AP1) binding activity is suppressed by 2-DG and restored by glucose treatment. Expression of either USF or AP1 activates the proximal OPN promoter in A7r5 VSMCs in part via the CCTCATGAC element. Moreover, glucose stimulates the transactivation functions of c-Fos and USF1, but not c-Jun, in one-hybrid assays. Mannitol does not regulate binding, transactivation functions, USF1 protein accumulation, or OPN transcription. Thus, OPN gene transcription is regulated by USF and AP1 in aortic VSMCs, entrained to changes in cellular glucose metabolism.

Acidic fibroblast growth factor signaling inhibits peroxynitrite-induced death of osteoblasts and osteoblast precursors

After trauma injury to the musculoskeletal system, conditions such as ischemia and inflammation involve excess production of superoxide (O2*), nitric oxide (*NO), and their reaction product, peroxynitrite (ONOO-). Exposure of murine osteoblasts and rat-derived primary osteoblast precursors to ONOO- resulted in a dose- and time-dependent delayed cell death that was more characteristic of apoptosis than necrosis. Exposure of both cell populations to ONOO- immediately enhanced phosphorylation and nitration of tyrosine residues within several polypeptides. Treatment of osteoblasts and osteoblast precursors with exogenous acidic fibroblast growth factor (FGF-1) enhanced cellular growth, increased endogenous levels of tyrosine phosphorylation, and significantly induced expression of both osteopontin and osteocalcin messenger RNA (mRNA) as well as osteopontin protein. Pretreatment of both cell populations with exogenous FGF-1 prevented ONOO(-)-mediated death. Cell signaling induced by FGF-1 pretreatment had no major effect of total levels of tyrosine nitration after ONOO- treatment. Collectively, these in vitro efforts show that FGF-1 signaling renders osteoblasts and osteoblast precursors resistant to the cytotoxic effects of ONOO-. Consequently, results presented here predict the therapeutic use of this growth factor for promoting the progression of bone repair mechanisms after fracture trauma.

Acidic fibroblast growth factor attenuates the cytotoxic effects of peroxynitrite in primary human osteoblast precursors

BACKGROUND

Skeletal injury and associated ischemia and inflammation induce the generation of pro-oxidants such as peroxynitrite (ONOO-), which has been demonstrated to induce apoptosis in several cell lines. Fibroblast growth factor (FGF-1) is important for coordinating osteogenesis and angiogenesis of osseous repair. In vitro studies were performed examining the effect of FGF-1 on human osteoblast progenitor stromal stem (HSS) cell proliferation, differentiation, and response to ONOO-.

METHODS

HSS cells were isolated and growth kinetics determined in the presence and absence of FGF-1. The effect of FGF-1 on HSS cell expression of osteoblast-specific osteopontin and osteocalcin mRNA and protein was examined by reverse transcriptase polymerase chain reaction and Western blot techniques. To determine the sensitivity of HSS cells to ONOO- in the absence and presence of FGF-1 pretreatment, cells were exposed to varying concentrations of the oxidant and examined for cell death using quantitative fluorescence staining with fluorescein diacetate and propidium diacetate.

RESULTS

Treatment of HSS cells with FGF-1 significantly enhanced cellular growth rates by 5 days (4.6 x 105 cells/mL vs. 3.1 x 105 cells/mL) and induced expression of both osteopontin and osteocalcin mRNA and protein. Exposure of HSS cells to ONOO- resulted in a dose- and time-dependent delayed cell death that was more characteristic of apoptosis than necrosis. Pretreatment of HSS cells with FGF-1 prevented ONOO- mediated apoptosis.

CONCLUSION

In vitro, treatment of HSS cells with FGF-1 stimulates cell growth and induces expression of differentiation markers specific to osteoblasts. FGF-1 treatment renders osteoblast precursors resistant to the cytotoxic effects of ONOO-. These results suggest that FGF-1 promotes the progression of bone repair mechanisms by increasing the population of osteoblasts and imparting protection to the cell line from the hostile inflammatory environment.