Exploring the role of extracellular matrix proteins to develop biomarkers of plaque vulnerability and outcome.

Cardiovascular disease (CVD) is the most common cause of death in industrialized countries. One underlying cause is atherosclerosis, which is a systemic disease characterized by plaques of retained lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins in the arterial wall. The biologic composition of an atherosclerotic plaque determines whether the plaque is more or less vulnerable, that is prone to rupture or erosion. Here, the ECM and tissue repair play an important role in plaque stability, vulnerability and progression. This review will focus on ECM remodelling in atherosclerotic plaques, with focus on how ECM biomarkers might predict plaque vulnerability and outcome.

Supplemental oxygen therapy does not affect the systemic inflammatory response to acute myocardial infarction.

BACKGROUND: Oxygen therapy has been used routinely in normoxemic patients with suspected acute myocardial infarction (AMI) despite limited evidence supporting a beneficial effect. AMI is associated with a systemic inflammation. Here, we hypothesized that the inflammatory response to AMI is potentiated by oxygen therapy. METHODS: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) multicentre trial randomized patients with suspected AMI to receive oxygen at 6 L min-1 for 6-12 h or ambient air. For this prespecified subgroup analysis, we recruited patients with confirmed AMI from two sites for evaluation of inflammatory biomarkers at randomization and 5-7 h later. Ninety-two inflammatory biomarkers were analysed using proximity extension assay technology, to evaluate the effect of oxygen on the systemic inflammatory response to AMI. RESULTS: Plasma from 144 AMI patients was analysed whereof 76 (53%) were randomized to oxygen and 68 (47%) to air. Eight biomarkers showed a significant increase, whereas 13 were decreased 5-7 h after randomization. The inflammatory response did not differ between the two treatment groups neither did plasma troponin T levels. After adjustment for increase in troponin T over time, age and sex, the release of inflammation-related biomarkers was still similar in the groups. CONCLUSIONS: In a randomized controlled setting of normoxemic patients with AMI, the use of supplemental oxygen did not have any significant impact on the early release of systemic inflammatory markers.

Functional and homeostatic defects of regulatory T cells in patients with coronary artery disease.

OBJECTIVE: Regulatory T cells (Tregs) are considered atheroprotective, and low levels have been associated with the acute coronary syndrome (ACS), particularly non-ST elevation (NSTE)-ACS. However, the functional properties as well as homeostasis of Tregs are mainly unknown in coronary artery disease (CAD). Here, we investigated the composition and functional properties of naïve (n) and memory (m)Tregs in patients with NSTE-ACS and in patients 6-12 months post-ACS. METHODS: Based on the expression of CD25, FOXP3, CD127, CD45RA, CD39 and CTLA-4, Treg subsets were defined by flow cytometry in whole blood or isolated CD4(+) T cells. The functional properties of nTregs and mTregs were examined in terms of proliferative capacity and modulation of cytokine secretion. To understand the potential consequences of Treg defects, we also investigated correlations with lipopolysaccharide (LPS)-induced cytokine secretion and ultrasound-defined carotid atherosclerosis. RESULTS: Both NSTE-ACS and post-ACS patients exhibited reduced levels of nTregs (P < 0.001) compared with healthy control subjects, but without compensatory increases in mTregs. Both nTregs and mTregs from patients showed significantly lower replicative rates and impaired capacity to modulate T-cell proliferation and secretion of interferon-gamma and IL-10. The Treg defect was also associated with LPS-induced cytokine secretion and increased burden of carotid atherosclerosis. CONCLUSION: Our results demonstrate a functional and homeostatic Treg defect in patients with NSTE-ACS and also in stabilized patients 6-12 months after ACS. Moreover, this defect was associated with a subclinical proinflammatory and atherogenic state. We believe that the failure to preserve Treg function and homeostasis reflects a need for immune-restoring strategies in CAD.

pT4 stage II and III colon cancers carry the worst prognosis in a nationwide survival analysis. Shepherd's local peritoneal involvement revisited.

The aim of this study is to clarify the prognostic importance of several well-known but still debated pathological variables related to the survival of colon cancer patients. The study focuses on the definition and survival carried by the pT4 category and stage II where the presence of high-risk variables may determine whether or not adjuvant chemotherapy is administered. A retrospective nationwide study was carried out including all colon cancer patients that underwent resection in Iceland between 1990 and 2004 (n = 889). All histopathology was reassessed. Cancer-specific survival (CSS) and overall survival were analysed using Kaplan-Meier and Cox regression analysis. In stage II, the five-year CSS for pT4 was 50% (95% CI, 32-69%), which was the lowest survival observed in that stage. In stage III the five-year CSS was 30% (95% CI, 18-41%) and 37% (95% CI, 26-48%) for pT4 and pN2 tumors, respectively. Lymphatic invasion and differentiation had no prognostic value in stage II. The survival associated with pT4a versus pT4b depends on how these categories are defined with regard to Shepherd's local peritoneal involvement (LPI). In the present series, pT4 is a major indicator of poor prognosis in patients with stage II and III colon carcinoma. Four-tiered TNM or Dukes staging systems are insufficient by not taking this variable into account. Only Shepherd's LPI4 and a subgroup of LPI3 (i.e., borderline LPI3/LPI4) should qualify for the pT4a subcategory. The results do not support lymphatic invasion or poor differentiation as high-risk stage II variables.

Natural killer (NK) cell deficit in coronary artery disease: no aberrations in phenotype but sustained reduction of NK cells is associated with low-grade inflammation.

Although reduced natural killer (NK) cell levels have been reported consistently in patients with coronary artery disease (CAD), the clinical significance and persistence of this immune perturbation is not clarified. In this study we characterized the NK cell deficit further by determining (i) differentiation surface markers and cytokine profile of NK cell subsets and (ii) ability to reconstitute NK cell levels over time. Flow cytometry was used to analyse NK cell subsets and the intracellular cytokine profile in 31 patients with non-ST elevation myocardial infarction (non-STEMI), 34 patients with stable angina (SA) and 37 healthy controls. In blood collected prior to coronary angiography, the proportions of NK cells were reduced significantly in non-STEMI and SA patients compared with controls, whereas NK cell subset analyses or cytokine profile measurements did not reveal any differences across groups. During a 12-month follow-up, the proportions of NK cells increased, although not in all patients. Failure to reconstitute NK cell levels was associated with several components of metabolic syndrome. Moreover, interleukin (IL)-6 levels remained high in patients with sustained NK cell deficit, whereas a decline in IL-6 (P < 0·001) was seen in patients with a pronounced increase in NK cells. In conclusion, we found no evidence that reduction of NK cells in CAD patients was associated with aberrations in NK cell phenotype at any clinical stage of the disease. Conversely, failure to reconstitute NK cell levels was associated with a persistent low-grade inflammation, suggesting a protective role of NK cells in CAD.

Provitamin A carotenoids are independently associated with matrix metalloproteinase-9 in plasma samples from a general population.

BACKGROUND AND AIM: Carotenoids in plasma are inversely associated with cardiovascular risk. Low levels can be explained by low dietary intake but also by a number of other factors including inflammatory activity. Given that matrix metalloproteinase (MMP)-9 has an important role in inflammation and cardiovascular disease, we hypothesized that circulating MMP-9 levels would be inversely related to total or single carotenoids in a general population cohort. METHODS: A well-characterized population-based cohort of 285 Swedish men and women (45-69 years) was used for the present study. The intake of carotenoid-rich fruits and vegetables was estimated from a food frequency questionnaire. Levels of MMP-9, C-reactive protein (CRP), interleukin (IL)-6 and six major carotenoids [ß-cryptoxanthine, α-carotene, ß-carotene, lutein (+zeaxanthin) and lycopene] were determined in plasma. RESULTS: Lower plasma levels of total and single carotenoids were associated with lower dietary intake of carotenoids, older age, male sex, lower physical activity, higher alcohol consumption, higher body mass index (BMI), higher systolic and diastolic blood pressures, lower levels of total cholesterol and HDL cholesterol and higher levels of CRP, IL-6 and MMP-9. After multivariate adjustments, plasma levels of total carotenoids and provitamin A carotenoids (ß-cryptoxanthine, α-carotene and ß-carotene) remained independently associated with sex, dietary intake of carotenoids, BMI, HDL cholesterol and MMP-9, whilst associations with CRP and IL-6 were not maintained. Neither dietary intake of carotenoid-rich fruits and vegetables, nor vitamin supplement use was associated with MMP-9, CRP or IL-6 levels. CONCLUSION: Plasma carotenoids were associated with a variety of factors including age, sex, dietary intake and metabolic variables. A new finding was the independent relationship in plasma between low provitamin A carotenoids and high MMP-9, suggesting a link between these carotenoids, matrix turnover and arterial remodelling.

Effects of simvastatin on carotenoid status in plasma.

BACKGROUND AND AIMS: Carotenoids are potent antioxidants mainly transported in the low density lipoprotein (LDL) fraction. They may also influence the immune response and inverse associations with inflammatory markers have been reported. We investigated whether simvastatin, by exerting both lipid-lowering and anti-inflammatory effects, altered the carotenoid status in plasma. METHODS AND RESULTS: A randomized, double-blind, placebo-controlled study design was applied. Eighty volunteers with mild to moderate hypercholesterolemia received either simvastatin 40 mg or placebo for 6 weeks. Lipids, oxidized LDL (ox-LDL), C-reactive protein (CRP), interleukin (IL)-6, oxygenated carotenoids (lutein, zeaxanthin, ß-cryptoxanthin) and hydrocarbon carotenoids (α-carotene, ß-carotene, lycopene) were measured in plasma. Simvastatin use was associated with significant reductions in total cholesterol, LDL, ox-LDL and CRP. Simvastatin therapy also resulted in reduced plasma levels of both oxygenated and hydrocarbon carotenoids. However, when adjusted for lipids, all carotenoids except ß-cryptoxanthin showed significant increases after simvastatin therapy. Both crude and lipid-adjusted carotenoids were inversely correlated with CRP and IL-6 in plasma but the change in carotenoid status during simvastatin therapy was not specifically related to any changes in inflammatory markers. CONCLUSIONS: To summarize, the change in carotenoid status during simvastatin therapy was mainly attributed to the lowering of cholesterol and not to the suppression of inflammatory activity. After adjustment for lipids, the levels of lutein, lycopene, α-carotene and ß-carotene were significantly increased by simvastatin suggesting an increased ratio of carotenoids per particle.

Expression of class II transplantation antigen on vascular smooth muscle cells in human atherosclerosis.

A large proportion of the cells of the human atherosclerotic plaque is assumed to be derived from medial smooth muscle cells. In contrast to these, the cells of the plaque have the capacity to accumulate lipid, and they also proliferate at a higher rate than medial cells. It has therefore been suggested that smooth muscle cells undergo a change of phenotype during atherogenesis, but there has been no evidence for such a change on the molecular level. We have now analyzed carotid artery plaques using a battery of antibodies against cell surface and cytoskeletal antigens, and found that most of the cells express the class II transplantation antigen (Ia antigen) HLA-DR. Also, the beta chain of HLA-DR was detected by immunoblotting of plaque extracts with the OKIa1 monoclonal antibody. HLA-DR is normally present on cells of the immune system, but only 60% of the DR-positive cells of the plaque reacted with monoclonal antibodies specific for macrophages and lymphocytes. Many of the remaining DR-positive cells contained the muscle-specific intermediate filament protein, desmin. This indicates that smooth muscle cells of atherosclerotic plaques express DR antigen. In contrast, very few DR-positive cells were found in normal human arteries. This suggests that expression of class II antigen is part of a phenotypic change in smooth muscle cells in atherosclerosis.

Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom.

In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered-subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.

Stress-induced release of the S100A8/A9 alarmin is elevated in coronary artery disease patients with impaired cortisol response.

Psychological stress is thought to be an important trigger of cardiovascular events, yet the involved pathways and mediators are largely unknown. Elevated systemic levels of the pro-inflammatory alarmin S100A8/A9 correlate with poor prognosis in coronary artery disease (CAD) patients. Here, we investigated the links between S100A8/A9 release and parameters of anti-inflammatory glucocorticoid secretion in two different cohorts subjected to a psychological stress test. In the first cohort of 60 CAD patients, psychological stress induced a rapid increase of circulating S100A8/A9. This rapid S100A8/A9 response strongly correlated with elevated evening saliva cortisol levels, suggesting an association with a dysregulated hypothalamic-pituitary-adrenal (HPA) axis. In the second cohort of 27 CAD patients and 28 controls, elevated S100A8/A9 levels were still detectable 24 h after stress in 40% of patients and 36% of controls, with a tendency for higher levels in patients. The sustained S100A8/A9 response was associated with a poor rapid cortisol release after stress in patients, but not in the control group. Our findings reveal for the first time that acute psychological stress induces elevated levels of S100A8/A9. We also provide hypothesis-generating evidence that dysregulated cortisol secretion in CAD patients might be associated with an exaggerated pro-inflammatory S100A8/A9 response.

Interferon-gamma inhibits lipoprotein lipase in human monocyte-derived macrophages.

Lipoprotein lipase (LPL) (EC 3.1.1.34) hydrolyzes triacylglycerols of very low density lipoproteins and chylomicrons. It is produced by several cell types, including macrophages, which are frequent in atherosclerotic lesions. The atherosclerotic plaque also contains activated T lymphocytes. We therefore investigated the possible regulatory effect of the T lymphocyte-derived lymphokine interferon-gamma (IFN-gamma) on macrophage LPL. Human monocyte-derived macrophages were treated with recombinant IFN-gamma or conditioned medium from activated peripheral blood mononuclear cells for 3 days. LPL activity was thereafter measured in the culture medium and in cell homogenates. The enzyme protein was detected at a cellular level by immunocytochemistry and immunopredicipitation. Recombinant IFN-gamma caused a profound decrease in macrophage LPL secretion. The IFN-gamma-treated cells, however, still contained immunodetectable enzyme and the decrease in secretion was apparently only partly due to an inhibited synthesis. Conditioned medium from activated peripheral blood mononuclear cells also drastically decreased the macrophage LPL secretion. When the conditioned medium was treated with antibodies against IFN-gamma, its down-regulating effect on macrophage LPL was totally removed. The data indicate that IFN-gamma is inhibiting macrophage LPL at least in part via a reduction of LPL synthesis. A local release of IFN-gamma may be important in the pathogenesis of atherosclerosis by affecting the lipid accumulation in the lesion.

Lipoprotein(a) and HLA-DRB1 and -DQB1 genes in coronary artery disease.

In some respects, atherosclerosis resembles autoimmune disease. Since many autoimmune diseases are associated with certain histocompatibility leukocyte antigen (HLA) class II alleles, we have looked for a similar HLA association with atherosclerosis. In the first phase, genomic typing was performed in 52 men with coronary artery disease. In the second phase, 50 men with early onset (before 50 years of age) coronary artery disease were studied. 12 DRB1 and 4 DQB1 alleles were determined by restriction fragment length polymorphism analysis. No significant difference in frequency of the examined alleles was observed in any of the patient groups compared to healthy controls. The plasma level of lipoprotein(a) (Lp(a)) is considered an important risk factor for early coronary heart disease. A linkage between inherited high levels of Lp(a) and certain HLA class II genotypes has been suggested. In the present study, Lp(a) levels were measured in men with early onset of coronary artery disease. 11 (23%) Study patients and 3 (7%) control subjects had Lp(a) levels above 450 mg/l. However, no correlation between high Lp(a) levels and certain HLA genotypes was found. Summarized, these findings indicate that atherosclerosis, especially early onset coronary atherosclerosis, is not a disease associated with particular HLA alleles.

Immunohistochemical localization of lipoprotein lipase in human adipose tissue.

The distribution of lipoprotein lipase (LPL) was studied in needle biopsies of human adipose tissue. Antibodies against bovine milk LPL react with and inhibit the activity of the human enzyme. These antibodies were used for immunohistochemical studies of the distribution of LPL in human adipose tissue. Immunoreactive enzyme was observed in adipocytes and connective tissue cells resembling preadipocytes. It was also seen in perivascular cells, in capillaries and in larger vessels. Intravenous administration of heparin led to a substantial decrease of immunodetectable LPL in vessels, whereas the enzyme in adipocytes and connective tissue cells was unaffected.

Localization of T lymphocytes and macrophages in fibrous and complicated human atherosclerotic plaques.

The cellular composition of aortic atherosclerotic plaques was analyzed by immunocytochemistry using cell type-specific monoclonal antibodies. T lymphocytes and monocytes/macrophages were detected both in early, fibrous plaques, and in more advanced, complicated ones. Many smooth muscle cells in these plaques expressed the class II MHC antigen, HLA-DR. Since this antigen is inducible by T cell products, our findings suggest that T cell-smooth muscle interactions occur during atherogenesis.

Gastric carcinoma: correlation of diagnosis based on biopsies and resection specimens with reference to the Laurén classification.

Gastric carcinomas in 382 patients were studied histologically and the results from the preoperative endoscopic biopsies were compared with those from the resected specimens. Using the Laurén classification an overall histological diagnostic agreement between the two specimens was reached in 317 cases, or 83%. The highest diagnostic agreement, 87%, was for intestinal carcinomas. For diffuse carcinomas the diagnostic agreement was 75%. The disagreement in intestinal carcinomas was mainly due to foci of undifferentiated cells and/or signet-ring cells predominating in the biopsy. The disagreement in diffuse carcinomas was mainly because glandular structures were present at the surface in some of the cases and therefore led to an erroneous diagnosis of intestinal carcinoma. In conclusion, the intestinal type of gastric carcinoma can in most cases be diagnosed correctly from an endoscopic biopsy, whereas the diagnosis of a diffuse carcinoma is less accurate until the resected specimen is available for histological study.

Apolipoprotein A-I-derived amyloid in atherosclerosis. Its association with plasma levels of apolipoprotein A-I and cholesterol.

Wild-type apolipoprotein A-I (apo A-I)-derived amyloid commonly occurs in atherosclerotic plaques. To clarify apo A-I amyloid formation, plasma levels of apo A-I and cholesterol were related to the presence of amyloid in atherosclerotic plaques in 15 patients with peripheral atherosclerosis, subjected to arterial reconstruction. Plasma levels of apo A-I and high-density lipoprotein (HDL) cholesterol were slightly higher in patients with apo A-I-derived amyloid than in those without, but the difference was not significant. Levels of low-density lipoprotein cholesterol and total cholesterol were significantly higher in the group with amyloid. High concentrations of apo A-I in the arterial intima are probably of greater importance to amyloid formation than high plasma levels of the protein. During atherosclerosis, the acute phase reactant serum amyloid A may displace apo A-I from HDL, leading to increased concentration of lipid-free apo A-I in the intima and conformational changes of apo A-I, which make it more fibrillogenic. Some forms of amyloid fibrils have been shown to be cytotoxic. Apo A-I-derived amyloid is possibly a pathogenically important factor in atherosclerosis.

Elevated levels of circulating matrix metalloproteinase-9 are associated with a dysregulated cortisol rhythm--A case-control study of coronary artery disease.

A dysregulated cortisol pattern has been found to be associated with systemic inflammatory activity in patients with coronary artery disease (CAD). Matrix metalloproteinase (MMP)-9 is involved in both inflammation and matrix degradation and considered a main contributor to coronary plaque rupture. In this study, we hypothesized that a dysfunctional cortisol response also involved a failure to regulate systemic MMP-9 levels in CAD patients. Total MMP-9, active MMP-9 and the endogenous inhibitor TIMP-1 were measured in 30 CAD patients and 30 healthy controls. Morning and evening cortisol was measured in repeated saliva samples. Patients had higher levels of total and active MMP-9 (both p<0.01) and increased 24-h cortisol output (p<0.05) characterized by higher levels of evening cortisol (p=0.011). MMP-9 was associated with evening cortisol (p<0.001) independent of smoking and inflammatory markers. Compared with controls, patients also showed a blunted cortisol response to stress. After stress, the levels of MMP-9 became significantly reduced in controls whereas they remained unchanged in patients. The data indicate that MMP-9 is differently regulated in patients due to a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and emphasize the role of MMP-9 as a possible link between stress and cardiovascular disease.