Infiltrating stromal immune cells in inflammatory breast cancer are associated with an improved outcome and increased PD-L1 expression.

BACKGROUND: Inflammatory breast cancer (IBC) is a rare and rapidly progressive form of invasive breast cancer. The aim of this study was to explore the clinical evolution, stromal tumour-infiltrating lymphocytes (sTIL) infiltration and programmed death-ligand 1 (PD-L1) expression in a large IBC cohort. PATIENTS AND METHODS: Data were collected prospectively from patients with IBC as part of an international collaborative effort since 1996. In total, 143 patients with IBC starting treatment between June 1996 and December 2016 were included. Clinicopathological variables were collected, and sTIL were scored by two pathologists on standard H&E stained sections. PD-L1 expression was assessed using a validated PD-L1 (SP142) assay. A validation cohort of 64 patients with IBC was used to test our findings. RESULTS: Survival outcomes of IBC remained poor with a 5-year overall survival (OS) of 45.6%. OS was significantly better in patients with primary non-metastatic disease who received taxane-containing (neo)adjuvant therapy (P = 0.01), had a hormone receptor-positive tumour (P = 0.001) and had lower cN stage at diagnosis (P = 0.001). PD-L1 positivity on immune cells (42.9%) was higher in IBC than in non-IBC in both our patient samples and the validation cohort. Furthermore, PD-L1 expression predicted pCR (P = 0.002) and correlated with sTIL infiltration (P < 0.001). sTIL infiltration of more than 10% of the stroma was a significant predictor of improved OS (HR 0.47, 95% CI 0.27-0.81, P = 0.006) in a multivariate model. CONCLUSIONS: IBC is characterised by poor survival and high PD-L1 immunoreactivity on sTIL. This suggests a role for PD1/PD-L1 inhibitors in the treatment of IBC. Furthermore, we showed that PD-L1 expression predicts response to neo-adjuvant therapy and that sTIL have prognostic significance in IBC.

Hypoxia regulates the production and activity of glucose transporter-1 and indoleamine 2,3-dioxygenase in monocyte-derived endothelial-like cells: possible relevance to infantile haemangioma pathogenesis.

BACKGROUND: Infantile haemangioma (IH) may present as a precursor area of pallor prior to the initial proliferative phase, which implies that the early lesion may be hypoxic. OBJECTIVES: To examine the effect of hypoxia on the expression and activity of two key molecular markers of IH, glucose transporter-1 (GLUT1) and indoleamine 2,3-dioxygenase (IDO). METHODS: IH endothelial cells express both haematopoietic and endothelial cell markers. CD14+ monocyte-derived endothelial-like cells have been employed in the study of IH and is the cell type used in this study. RESULTS: GLUT1 transcript, protein and activity levels were strongly induced by hypoxia and remained elevated following 2 days of normoxic recovery. IDO transcript levels were not affected by hypoxia, although IDO protein level was reduced fivefold and IDO activity >100-fold following 2 days of hypoxia. The protein and activity levels returned to normal following 2 days of normoxic recovery. CONCLUSIONS: The findings link the tissue hypoxia that precedes lesion development and the expression and/or activity of two key IH proteins. The early hypoxic insult may contribute to the elevated GLUT1 levels in IH lesions, while the very low IDO activity during the hypoxic phase may promote activation of immune cells in the lesion, which release cytokines that trigger IDO expression and activity and entry into the proliferative phase. Interestingly, IH lesion development shares some common features with ischaemia-reperfusion injury.

Wegener's granulomatosis presenting as a thyroid mass.

A 71-year-old patient was referred for suspected hyperthyroidism because of a 15-kg weight loss, suppressed thyroid stimulating hormone (TSH), and a 4-cm nodule in the left thyroid lobe. Both free T4 and T3 were normal. Antithyroglobulin, anti-TSH receptor and antimicrosomal antibodies were absent. Thyroid scintigraphy showed a cold nodule in the left thyroid lobe. CAT scan of the neck revealed a 4-cm inhomogeneous nodule at the left side. An elevated sedimentation rate suggested bacterial thyroiditis, localized Quervain thyroiditis, malignancy, and the fibrosing variant of Hashimoto's thyroiditis or Riedel's thyroiditis. A fine needle biopsy of the thyroid nodule showed no malignant cells but was inconclusive. A true cut biopsy demonstrated atypical inflammation and also failed to reveal the diagnosis. Therefore, the patient was admitted to the hospital for further work-up and was unexpectedly found to have nodular lesions in the lung on a chest X-ray. Additional blood analysis revealed a positive cytoplasmic ANCA-titer. After inconclusive peripheral lung biopsies, a left hemithyroidectomy and a very large video-assisted thoracoscopic lung biopsy were performed, both revealing extensive zones of necrosis surrounded by granulomatous foci pointing to the diagnosis of Wegener's granulomatosis (WG) disease. To our knowledge, this is the first report of a well-documented WG of the thyroid gland. Although extremely rare, WG should be included in differential diagnosis of inflammatory lesions of the thyroid gland.

Oxidative DNA damage and repair in experimental atherosclerosis are reversed by dietary lipid lowering.

Increased oxidative stress is a major characteristic of hypercholesterolemia-induced atherosclerosis. The oxidative environment is mainly created by the production of reactive oxygen species, which are assumed to mediate vascular tissue injury. Oxidative DNA damage resulting from free radical attack remains, however, a poorly examined field in atherosclerosis. Male New Zealand White rabbits were fed a cholesterol-rich diet (0.3%) for 24 weeks. The induced atherosclerotic plaques showed elevated levels of the DNA damage marker 7,8-dihydro-8-oxoguanine (8-oxoG) as demonstrated by immunohistochemistry. 8-oxoG immunoreactivity was found predominantly in the superficial layer of the plaque containing numerous macrophage-derived foam cells but not in the media or in arteries of age-matched control animals. Alkaline single-cell gel electrophoresis revealed that the number of DNA strand breaks was significantly higher in the plaque as compared with control samples of normolipemic animals. These changes were associated with the upregulation of DNA repair enzymes (poly[ADP-ribose] polymerase-1, p53, phospho-p53 [phosphorylated at Ser392], and XRCC1 [x-ray repair cross-complementing 1]). DNA strand breaks normalized after 4 weeks of dietary lipid lowering. However, a significant reduction of 8-oxoG immunoreactivity was only observed after a prolonged period of lipid lowering (12 to 24 weeks). Repair pathways started to decline progressively when cholesterol-fed animals were placed on a normal diet. In conclusion, oxidative DNA damage and increased levels of DNA repair, both associated with diet-induced hypercholesterolemia, are strongly reduced during dietary lipid lowering. These findings may provide a better insight into the benefits of lipid-lowering therapy on plaque stabilization.

Macrophage p53 deficiency leads to enhanced atherosclerosis in APOE*3-Leiden transgenic mice.

Cell proliferation and cell death (either necrosis or apoptosis) are key processes in the progression of atherosclerosis. The tumor suppressor gene p53 is an essential gene in cell proliferation and cell death and is upregulated in human atherosclerotic plaques, both in smooth muscle cells and in macrophages. In the present study, we investigated the importance of macrophage p53 in the progression of atherosclerosis using bone marrow transplantation in APOE*3-Leiden transgenic mice, an animal model for human-like atherosclerosis. APOE*3-Leiden mice were lethally irradiated and reconstituted with bone marrow derived from either p53-deficient (p53(-/-)) or control (p53(+/+)) donor mice. Reconstitution of mice with p53(-/-) bone marrow did not result in any hemopoietic abnormalities as compared with p53(+/+) transplanted mice. After 12 weeks on an atherogenic diet, APOE*3-Leiden mice reconstituted with p53(-/-) bone marrow showed a significant (P=0.006) 2.3-fold increase in total atherosclerotic lesion area as compared with mice reconstituted with p53(+/+) bone marrow. Although likely a secondary effect of the increased lesion area, p53(-/-) transplanted mice also showed significantly more lesion necrosis (necrotic index, 1.1+/-1.3 versus 0.2+/-0.7; P=0.04) and lesion macrophages (macrophage area, 79.9+/-40.0 versus 39.7+/-27.3x10(3) micrometer(2) per section; P=0.02). These observations coincided with a tendency toward decreased apoptosis (terminal deoxynucleotidyl transferase end-labeling [TUNEL]-positive nuclei going from 0.42+/-0.39 to 0.14+/-0.15%, P=0.071), whereas the number of proliferating cells (5'-bromo-2'-deoxyuridine-positive nuclei) was not affected (3.75+/-0.98 versus 4.77+/-2.30%; P=0.59). These studies indicate that macrophage p53 is important in suppressing the progression of atherosclerosis and identify a novel therapeutic target for regulating plaque stability.

Frozen section in thyroid surgery.

OBJECTIVE: We studied the use of frozen section in the detection of malignancy in thyroid surgery in a large teaching hospital. MATERIALS AND METHODS: We reviewed all case notes of patients operated on for thyroid disease between January 1st 1997 and December 31st 2004. We identified 420 operations in 408 patients. Data were available for 417 operations. RESULTS: In patients with a solitary thyroid nodule, a frozen section is sometimes performed. Frozen section was done in 128 of 417 operations. The specificity for malignancy was 98.16%. The positive predictive value was 81.81% and the negative predictive value 93.85%. However the sensitivity was 56.25%. Frozen section is a time-consuming investigation. With follicular lesions it is very difficult to distinguish between benign disease and malignancy since the diagnosis of malignancy depends on capsular and/or blood vessel invasion. Also it costs about 100 Euro (approximately 125 dollars). CONCLUSION: This study confirms that adequate histopathologic diagnosis of thyroid disease is based on extensive subsampling of the specimen which is not possible during a peroperatory frozen section procedure.

Atherosclerosis in APOE*3-Leiden transgenic mice: from proliferative to atheromatous stage.

BACKGROUND: This study documents (1) the progression of atherosclerosis along the entire arterial tree in APOE*3-Leiden mice after 1, 4, 6, 9, and 12 months of a high-fat/high-cholesterol (HFC) diet and (2) the amount and phenotype of DNA-synthesizing and apoptotic cells in different lesion types after 6 months of HFC diet. METHODS AND RESULTS: Diet duration was correlated with a craniocaudal progression of lesion development and with an increase in severity of the lesion. Typically, the lesions contained smooth muscle cells, macrophages, and T lymphocytes and were covered by an intact endothelium. Whereas DNA synthesis (BrdU uptake) was usually elevated in type II lesions (8.6+/-0.8% versus 1.0+/-0.2% in the nondiseased arterial wall; P<0.05), apoptosis was found primarily in advanced lesions (type IV, 1.3+/-0.1% and type V, 1.2+/-0.2% versus 0.04+/-0.04% in the nondiseased arterial wall [P<0.05]). Cell phenotyping revealed that the majority of DNA synthesis and apoptosis was confined to the macrophage-derived foam cell (68.6+/-3. 0% and 82.2+/-4.6%, respectively). CONCLUSIONS: This study shows that in APOE*3-Leiden mice, duration of an HFC diet is associated with (1) a craniocaudal progression of lesion development and (2) an increased complexity of atherosclerotic lesions. Furthermore, DNA synthesis is predominant in early lesions, whereas apoptosis is present mainly in more advanced lesions. Both parameters of cell turnover are confined primarily to the macrophage-derived foam cell.

Adenoviral expression of a urokinase receptor-targeted protease inhibitor inhibits neointima formation in murine and human blood vessels.

BACKGROUND: Smooth muscle cell migration, in addition to proliferation, contributes to a large extent to the neointima formed in humans after balloon angioplasty or bypass surgery. Plasminogen activator/plasmin-mediated proteolysis is an important mediator of this smooth muscle cell migration. Here, we report the construction of a novel hybrid protein designed to inhibit the activity of cell surface-bound plasmin, which cannot be inhibited by its natural inhibitors, such as alpha(2)-antiplasmin. This hybrid protein, consisting of the receptor-binding amino-terminal fragment of uPA (ATF), linked to the potent protease inhibitor bovine pancreas trypsin inhibitor (BPTI), can inhibit plasmin activity at the cell surface. METHODS AND RESULTS: The effect of adenovirus-mediated ATF.BPTI expression on neointima formation was tested in human saphenous vein organ cultures. Infection of human saphenous vein segments with Ad.CMV.ATF.BPTI (5x10(9) pfu/mL) resulted in 87.5+/-3.8% (mean+/-SEM, n=10) inhibition of neointima formation after 5 weeks, whereas Ad.CMV.ATF or Ad.CMV.BPTI virus had only minimal or no effect on neointima formation. The efficacy of ATF.BPTI in vivo was demonstrated in a murine model for neointima formation. Neointima formation in the femoral artery of mice, induced by placement of a polyethylene cuff, was strongly inhibited (93.9+/-2%) after infection with Ad.CMV.mATF.BPTI, a variant of ATF.BPTI able to bind specifically to murine uPA receptor; Ad.CMV.mATF and Ad.CMV.BPTI had no significant effect. CONCLUSIONS: These data provide evidence that adenoviral transfer of a hybrid protein that binds selectively to the uPA receptor and inhibits plasmin activity directly on the cell surface is a powerful approach to inhibiting neointima formation and restenosis.

Epidermal differentiation does not involve the pro-apoptotic executioner caspases, but is associated with caspase-14 induction and processing.

The epidermis is a stratified squamous epithelium in which keratinocytes progressively undergo terminal differentiation towards the skin surface leading to programmed cell death. In this respect we studied the role of caspases. Here, we show that caspase-14 synthesis in the skin is restricted to differentiating keratinocytes and that caspase-14 processing is associated with terminal epidermal differentiation. The pro-apoptotic executioner caspases-3, -6, and -7 are not activated during epidermal differentiation. Caspase-14 does not participate in apoptotic pathways elicited by treatment of differentiated keratinocytes with various death-inducing stimuli, in contrast to caspase-3. In addition, we show that non-cornifying oral keratinocyte epithelium does not express caspase-14 and that the parakeratotic regions of psoriatic skin lesions contain very low levels of caspase-14 as compared to normal stratum corneum. These observations strongly suggest that caspase-14 is involved in the keratinocyte terminal differentiation program leading to normal skin cornification, while the executioner caspases are not implicated. Cell Death and Differentiation (2000) 7, 1218 - 1224

Inhibition of accelerated atherosclerosis in vein grafts by placement of external stent in apoE*3-Leiden transgenic mice.

OBJECTIVE: Vein grafts fail because of the development of intimal hyperplasia and accelerated atherosclerosis. Placement of an external stent around vein grafts resulted in an inhibition of intimal hyperplasia in several animal studies. Here, we assess the effects of external stenting on accelerated atherosclerosis in early vein grafts in carotid arteries in hypercholesterolemic apolipoprotein E*3-Leiden transgenic mice. METHODS AND RESULTS: Venous interposition grafting was performed in apolipoprotein E*3-Leiden mice fed standard chow or a highly cholesterol-rich diet for 4 weeks. After engraftment, external stents with different inner diameters (0.4 or 0.8 mm) were placed. In unstented vein grafts in hypercholesterolemic mice, thickening up to 50 times the original thickness, with foam cell-rich lesions, calcification, and necrosis, was observed within 28 days. The atherosclerotic lesions observed show high morphological resemblance to atherosclerotic lesions observed in human vein grafts. In stented vein grafts in hypercholesterolemic mice, no foam cell accumulation or accelerated atherosclerosis was observed. Compared with unstented vein grafts, stenting of vein grafts in a hypercholesterolemic environment resulted in a 94% reduction of vessel wall thickening. These effects were independent of stent size. CONCLUSIONS: Extravascular stent placement results in strong inhibition of accelerated vein graft atherosclerosis in hypercholesterolemic transgenic mice and thereby provides a perspective for therapeutic intervention in vein graft diseases.

Apoptosis in atherosclerosis: beneficial or detrimental?

Several groups have demonstrated apoptotic cell death in atherosclerotic plaques. The significance of apoptosis in atherosclerosis depends on the stage of the plaque, localization and the cell types involved. Both macrophages and smooth muscle cells undergo apoptosis in atherosclerotic plaques. Apoptosis of macrophages is mainly present in regions showing signs of DNA synthesis/repair. Smooth muscle cell apoptosis is mainly present in less cellular regions and is not associated with DNA synthesis/repair. Even in early stages of atherosclerosis smooth muscle cells become susceptible to undergoing apoptosis since they increase different pro-apoptotic factors. Moreover, recent data indicate that smooth muscle cells may be killed by activated macrophages. The loss of the smooth muscle cells can be detrimental for plaque stability since most of the interstitial collagen fibers, which are important for the tensile strength of the fibrous cap, are produced by SMC. Apoptosis of macrophages could be beneficial for plaque stability if apoptotic bodies are removed. Apoptotic cells that are not scavenged in the plaque activate thrombin which could further induce intraplaque thrombosis. It can be concluded that apoptosis in the primary atherosclerosis is detrimental since it could lead to plaque rupture and thrombosis. Recent data of our group indicate that apoptosis decreases after lipid lowering which could be important in our understanding of the cell biology of plaque stabilization.

Apoptotic versus autophagic cell death in heart failure.

OBJECTIVE: Progressive loss of cardiomyocytes is one of the most important pathogenic characteristics of heart failure. Apoptosis may be an important mode of cell death in heart failure but it must be demonstrated by multiple criteria and not just TUNEL staining alone. Previously, we and others have demonstrated that besides apoptosis other phenomena like active gene transcription can result in TUNEL positivity. Moreover, other types of cell death that are caspase-independent could be important in heart failure. This study examined the hypothesis whether TUNEL labeling parallels caspase activation. METHODS: Cardiac tissue of patients in the terminal stage of heart failure as a consequence of ischaemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) were studied. Embryonic mice hearts were used for positive control for detection of the classical apoptosis. RESULTS: In mice embryonic hearts we could clearly find apoptotic cell death detected by TUNEL labeling and immunohistochemistry for activated caspase-3. In heart failure, TUNEL-positive cardiomyocytes were negative for active caspase-3 but showed signs of active gene transcription (SC-35). However, autophagic cell death could be found in 0.3% of the cardiomyocytes. Autophagic cell death was demonstrated by granular cytoplasmic ubiquitin inclusions, an established marker of autophagocytosis in neurons. Interestingly, these autophagic cardiomyocytes were TUNEL and activated caspase-3 negative but were also negative for C9, a marker for necrosis. Western blot analysis confirmed that in cardiomyopathies no cleavage of caspase-3 and caspase-7 occurred. CONCLUSION: The present study demonstrates two fundamentally different situations of cell death in cardiac tissue. In embryonic mice, cardiomyocytes undergo caspase-dependent cell death. However, cardiomyocytes in heart failure show caspase-independent autophagic cell death rather than apoptotic cell death.

Cardiac remodeling after myocardial infarction is impaired in IGF-1 deficient mice.

OBJECTIVE: To obtain more insight in the role of IGF-1 in cardiac remodeling and function after experimental myocardial infarction. We hypothesized that cardiac remodeling is altered in IGF-1 deficient mice, which may affect cardiac function. METHODS: A myocardial infarction was induced by surgical coronary artery ligation in heterozygous IGF-1 deficient mice. One week after surgery, left ventricular function was analyzed, and parameters of cardiac remodeling were measured. RESULTS: No significant difference in cardiac function was found between infarcted wildtype and knock-out animals, despite a marked reduction in capillarization and blunting of the hypertrophic response of the interventricular septum in the IGF-1 deficient group. Furthermore, decreased DNA synthesis and increased apoptosis rates were observed in the IGF-1 knock-out mice. CONCLUSION: IGF-1 deficient mice show preservation of cardiac function 1 week after MI, despite an altered cardiac remodeling process.

Exposure to oxidized low-density lipoprotein in vivo enhances intimal thickening and selectively impairs endothelium-dependent dilation in the rabbit.

OBJECTIVES: Based on in vitro studies, oxidized low-density lipoprotein (oxLDL) has been implicated in atherogenesis and the associated deficiency in endothelium-dependent relaxation. The aim of this study was to investigate the effects of in vivo exposure to oxLDL on intimal thickening and relaxing behaviour. METHODS: Intimal thickening was evoked by the placement of silicone collars around the carotid arteries of the rabbit for 3 or 14 days. OxLDL (Cu(2+)-oxidized, 7 micron/h) or the vehicle phosphate-buffered saline (PBS) was infused in the collars via subdermally implanted osmotic minipumps. RESULTS: The collared vessels receiving PBS developed discrete intimal thickening after 14 days (intima/media (I/M) ratio 11 +/- 2%). OxLDL infusion resulted in intimal thickening after 3 days and significantly enhanced the intimal thickness by 14 days (I/M ratio 98 +/- 16%). Collaring alone for 3 or 14 days and 3 days exposure to oxLDL did not impair the endothelium-dependent relaxations to acetylcholine or calcium ionophore, nor to the NO donors glyceryl trinitrate (GTN) and S-nitroso-N-acetylpenicillamine (SNAP). However, the sensitivity to acetylcholine was decreased after exposure to oxLDL for 14 days (-logEC50 oxLDL 6.95 +/- 0.11 vs. 7.52 +/- 0.11 collar alone) and the maximal relaxation to the endothelium-dependent agonist was reduced by 50%, this in the presence of a virtually intact endothelium. Complete relaxation was still obtained with the nitric oxide donors. CONCLUSION: Our results show for the first time that local vascular exposure to oxLDL in vivo promotes intimal thickening and inhibits endothelium-dependent dilation, thereby supporting an active role for oxLDL in the morphological and functional changes observed in atherosclerotic blood vessels.

Inducible nitric oxide synthase colocalizes with signs of lipid oxidation/peroxidation in human atherosclerotic plaques.

OBJECTIVE: Advanced human atherosclerotic plaques are characterized by the abundant presence of the autofluorescent non-soluble lipid pigment ceroid, consisting of oxidized lipoproteins. The aim of the present study was to examine the topographical and cellular distribution of inducible nitric oxide synthase (iNOS or NOS II) within different stages of atherosclerosis and its colocalization with ceroid deposits and nitrotyrosine. METHODS AND RESULTS: Different stages of atherosclerosis were studied by immunohistochemistry on whole-mount longitudinal sections of carotid endarterectomy specimens. In the adaptive intimal thickening the predominant cell type were smooth muscle cells. The fatty streaks contained both smooth muscle cells and macrophages with an extremely low NOS II immunoreactivity. The advanced atherosclerotic plaques however, showed a very dense infiltration by macrophages, of which a subpopulation expressed NOS II as a vesicular immunoreactivity in their cytoplasm. These were mainly present around the necrotic core, in association with ceroid accumulation and nitrotyrosine. Fluorescence quenching microscopy showed the presence of NOS II on autofluorescent ceroid vesicles in the macrophages. Large extracellular ceroid granules were not NOS II immunoreactive. NOS II mRNA was detected by RT-PCR and the protein by Western blot in the plaque tissue but not in mammary arteries used as controls. CONCLUSION: Ceroid, nitrotyrosine and NOS II colocalized in late stages of atherosclerosis and were found around the necrotic core in the plaque. This could suggest that NOS II expression in macrophages is involved in oxidation and peroxidation of lipids, leading to ceroid formation.

Distribution of cell replication and apoptosis in atherosclerotic plaques of cholesterol-fed rabbits.

In human atherosclerosis the development of a cell-poor lipid-rich core is an important feature of atheromatous plaque formation. The core is characterized by extracellular lipid deposition, cholesterol crystals and cell death and is situated in the deep layer of the plaque. The aim of the present study was to localize apoptotic cell death and cell replication in atherosclerotic plaques of cholesterol-fed rabbits in order to examine the hypothesis that core formation is a consequence of an imbalance between cell replication and apoptosis. New Zealand White male rabbits were fed a diet supplemented with 0.3% cholesterol for 16 (n = 5) and 27 weeks (n = 9). Cell replication and cell types were demonstrated by immunohistochemistry and apoptotic cell death was demonstrated by DNA in situ end-labeling (ISEL) and transmission electron microscopy. Quantification was done using a colour image analysis system. The plaques showed a clear distinction between a luminal layer composed of numerous lipid-rich foam cells of macrophage origin and a deep layer which was fibrous, containing extracellular lipid deposits and few smooth muscle cells. Cell replication (expressed as percentage of total number of nuclei) in the superficial layer was higher then in the deep layer at both 16 (5.1 +/- 1.8% vs. 1.2 +/- 0.8%) and 27 weeks (11.3 +/- 2.1% vs. 4.4 +/- 1.0%). This was also the case for the total number of nuclei per 50000 microns2 cross-sectional intimal area (numerical density): 235 +/- 13 vs. 147 +/- 7 at 16 weeks and 130 +/- 10 vs. 89 +/- 11 at 27 weeks. Apoptotic cell death (expressed as percentage of total number of nuclei) was low and there was no difference between the superficial and the deep layers of the plaques (0.8% +/- 0.2% vs. 0.4% +/- 0.2% at 16 weeks and 0.6 +/- 0.2% vs. 1.7% +/- 0.6% at 27 weeks). Our results indicate that the control of cell number in superficial vs. deep regions of the plaque is mainly a consequence of differences in cell replication. This may be due to a gradient of endothelial and plasma-derived growth factors. Cells can disappear by apoptosis, albeit at a relatively low level, throughout the lesion. This process may contribute to the pronounced cell loss in more advanced human atherosclerotic plaques, setting the base for plaque rupture.

Time course of osteopontin, osteocalcin, and osteonectin accumulation and calcification after acute vessel wall injury.

Although mineral deposits have long been described to be a prominent feature of atherosclerosis, the mechanisms of arterial calcification are not well understood. However, accumulation of the non-collagenous matrix bone-associated proteins, osteopontin, osteocalcin, and osteonectin, has been demonstrated in atheromatous plaques. The aim of this study was to evaluate the role of these proteins in arterial calcification and, more precisely, during the initiation of this process. A model of rapid aortic calcification was developed in rabbits by an oversized balloon angioplasty. Calcification was followed using von Kossa staining and osteopontin, osteocalcin, and osteonectin were identified using immunohistochemistry. The aortic injury was rapidly followed by calcified deposits that appeared in the media as soon as 2 days after injury and then accumulated in zipper-like structures. Osteonectin was not detected in calcified deposits at any time after injury. In contrast, osteopontin and osteocalcin were detected in 8- and 14-day calcified structures, respectively, but not in the very early 2-day mineral deposits. These results suggest that these matrix proteins, osteopontin, osteocalcin, and osteonectin, are not involved in the initiation step of the aortic calcification process and that the former two might play a role in the regulation of arterial calcification.

Fibrate-modulated expression of fibrinogen, plasminogen activator inhibitor-1 and apolipoprotein A-I in cultured cynomolgus monkey hepatocytes -- role of the peroxisome proliferator-activated receptor-alpha.

Fibrates are used to lower plasma triglycerides and cholesterol levels in hyperlipidemic patients. In addition, fibrates have been found to alter the plasma concentrations of fibrinogen, plasminogen activator inhibitor-1 (PAI-1) and apolipoprotein A-I (apo A-I). We have investigated the in vitro effects of fibrates on fibrinogen, PAI-1 and apo A-I synthesis and the underlying regulatory mechanisms in primary monkey hepatocytes. We show that fibrates time- and dose-dependently increase fibrinogen and apo A-I expression and decrease PAI-1 expression in cultured cynomolgus monkey hepatocytes, the effects demonstrating different potency for different fibrates. After three consecutive periods of 24 h the most effective fibrate. ciprofibrate (at 1 mmol/l), increased fibrinogen and apo A-I synthesis to 356% and 322% of control levels, respectively. Maximum inhibition of PAI-1 synthesis was about 50% of control levels and was reached by 1 mmol/l gemfibrozil or ciprofibrate after 48 h. A ligand for the retinoid-X-receptor (RXR), 9-cis retinoic acid, and specific activators of the peroxisome proliferator-activated receptor-alpha (PPARalpha), Wy14,643 and ETYA, influenced fibrinogen, PAI-1 and apo A-I expression in a similar fashion, suggesting a role for the PPARalpha/RXRalpha heterodimer in the regulation of these genes. When comparing the effects of the various compounds on PPARalpha transactivation activity as determined in a PPARalpha-sensitive reporter gene system and the ability of the compounds to affect fibrinogen, PAI-1 and apo A-I antigen production, a good correlation (r=0.80; p <0.01) between PPARalpha transactivation and fibrinogen expression was found. Apo A-I expression correlated only weakly with PPARalpha transactivation activity (r=0.47; p=0.24), whereas such a correlation was absent for PAI-1 (r=0.03; p=0.95). These results strongly suggest an involvement of PPARalpha in the regulation of fibrinogen gene expression.

Relationship between visceral fat and PAI-1 in overweight men and women before and after weight loss.

This study was aimed at evaluating the relationship between visceral fat accumulation and plasma plasminogen activator inhibitor-1 (PAI-1) levels in healthy, obese men and women undergoing weight loss therapy. The subjects, 25 men and 25 premenopausal women, aged between 26 and 49 years, with an initial body mass index between 28 and 38 kg/m2, received a controlled diet for 13 weeks providing a 4.2 MJ/day energy deficit. Magnetic resonance imaging was used to measure visceral and subcutaneous abdominal fat. Our results show that before weight loss visceral fat was significantly correlated with PAI-1 in men (r = 0.45; p<0.05), but not in women (r = -0.15; ns). The association between visceral fat and PAI-1 in men remained significant after adjustment for age and total fat mass, and multiple linear regression analysis showed a significant independent contribution of visceral fat to plasma PAI-1 levels. Both visceral fat areas and PAI-1 levels decreased significantly with weight loss in both men and women. Changes in visceral fat area were related to changes in PAI-1 in women (r = -0.43; p = 0.05) but not in men (r = -0.01; ns); however, this association in women disappeared after adjustment for total fat mass. We conclude that there is a relationship between visceral fat and PAI-1 in obese men but not in obese women, and that PAI-1 levels decrease substantially (52%) by weight loss, but this change is not related to changes in visceral fat mass per se.

Effects of gemfibrozil and ciprofibrate on plasma levels of tissue-type plasminogen activator, plasminogen activator inhibitor-1 and fibrinogen in hyperlipidaemic patients.

Evaluation of fibrate treatment in humans has focused primarily on its anti-lipidaemic effects. A potentially favourable haemostasis-modulating activity of fibrates has also been recognized but the data are not consistent. We sought to learn more about this variability by examining the effects of gemfibrozil and ciprofibrate on plasma levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and fibrinogen in primary hyperlipidaemic patients after six and twelve weeks of treatment using different assay systems for PAI-1 and fibrinogen. Although both fibrates effectively lowered triglyceride and cholesterol levels, no effect on the elevated baseline antigen levels of t-PA and PAI-1 was observed after fibrate treatment. However, both fibrates influenced plasma fibrinogen levels, albeit in a different way. Fibrinogen antigen levels were elevated by 17.6% (p <0.05) and 24.3% (p <0.001) with gemfibrozil after six and twelve weeks, respectively, whereas with ciprofibrate there was no effect. Using a Clauss functional assay with either a mechanical end point or a turbidity-based end point, no significant change in fibrinogen levels was seen after six weeks of gemfibrozil treatment. However, after twelve weeks, gemfibrozil enhanced functional fibrinogen levels by 7.2% (p <0.05) as assessed by the Clauss mechanical assay, but decreased functional fibrinogen levels by 12.5% (p <0.0001) when a Clauss assay based on turbidity was used. After six or twelve weeks of ciprofibrate treatment, functional fibrinogen levels were decreased by 10.1% (p <0.001) and 10.5% (p <0.0001), respectively on the basis of Clauss mechanical and by 14.2% (p <0.001) and 28.2% (p <0.0001), respectively with the Clauss turbidimetric assay. A remarkable and consistent finding with both fibrates was the decrease in functionality of fibrinogen as assessed by the ratio of functional fibrinogen (determined by either of the two Clauss assays) to fibrinogen antigen. Taken together, our results indicate that at least part of the variability in the effects of fibrates on haemostatic parameters can be explained by intrinsic differences between various fibrates, by differences in treatment period and/or by the different outcomes of various assay systems. Interestingly, the two fibrates tested both reduced the functionality of fibrinogen.