| 1. |
- Leinonen, E. S., et al.
(author)
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Low-grade inflammation, endothelial activation and carotid intima-media thickness in type 2 diabetes
- 2004
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In: J Intern Med. ; 256:2, s. 119-27
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Journal article (peer-reviewed)abstract
- OBJECTIVES: The objective of this study was to assess the relationship between inflammation, endothelial activation and incipient atherosclerosis in type 2 diabetes. DESIGN: Cross-sectional study. Setting and subjects. We studied 239 type 2 diabetic patients [71 with clinical cardiovascular disease (CVD)] and 78 healthy control subjects, aged 50-75 in a single research centre. METHODS: Carotid intima-media thickness (IMT) was determined by ultrasound. Circulating intracellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, ultra-sensitive C-reactive protein, human serum amyloid A, interleukin-6, monocyte colony-stimulating factor, secretory nonpancreatic phospholipase A(2) type IIA, glucose, HbA1c, and lipid/lipoprotein variables were measured. RESULTS: Carotid IMT was significantly thicker in diabetic patients than healthy controls across the whole age range. IMT was also thicker in diabetic patients with, than without, CVD, but this difference disappeared after controlling for confounding factors. Concentrations of the inflammatory and endothelial markers except IL-6 were significantly higher in the diabetic patients than in healthy controls, but comparable in diabetic patients with and without CVD. The main determinants of IMT in the diabetic patients were blood pressure, age and diabetes duration. CONCLUSIONS: Low-grade inflammation and endothelial activation are increased in diabetic patients but do not associate with IMT or clinical CVD. The inflammatory reaction seems to be rather a feature of the metabolic syndrome than a direct determinant of atherosclerosis.
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| 2. |
- Boström, Pontus, 1982, et al.
(author)
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Hypoxia converts human macrophages into triglyceride-loaded foam cells.
- 2006
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In: Arteriosclerosis, thrombosis, and vascular biology. - 1524-4636. ; 26:8, s. 1871-6
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Atherosclerotic lesions have regions that are hypoxic. Because the lesion contains macrophages that are loaded with lipid, we investigated whether hypoxia can influence the accumulation of lipids in these cells. METHODS AND RESULTS: Exposure of human macrophages to hypoxia for 24 hours resulted in an increased formation of cytosolic lipid droplets and an increased accumulation of triglycerides. Exposure of the macrophages to oxidized low-density lipoprotein (oxLDL) increased the accumulation of cytosolic lipid droplets because of an increase in cellular cholesterol esters. The accumulation of lipid droplets in oxLDL-treated cells was further increased after hypoxia, caused by an increased level of triglycerides. Expression analyses combined with immunoblot or RT-PCR demonstrated that hypoxia increased the expression of several genes that could promote the accumulation of lipid droplets. Hypoxia increased the mRNA and protein levels of adipocyte differentiation-related protein (ADRP). It is well known that an increased expression of ADRP increases the formation of lipid droplets. Hypoxia decreased the expression of enzymes involved in beta-oxidation (acyl-coenzyme A synthetase and acyl-coenzyme A dehydrogenase) and increased the expression of stearoyl-coenzyme A desaturase, an important enzyme in the fatty acid biosynthesis. Moreover, exposure to hypoxia decreased the rate of beta-oxidation, whereas the accumulation of triglycerides increased. CONCLUSIONS: The results demonstrate that exposure of human macrophages to hypoxia causes an accumulation of triglyceride-containing cytosolic lipid droplets. This indicates that the hypoxia present in atherosclerotic lesions can contribute to the formation of the lipid-loaded macrophages that characterize the lesion and to the accumulation of triglycerides in such lesions.
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| 3. |
- Hägg, Daniel, 1974, et al.
(author)
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Augmented levels of CD44 in macrophages from atherosclerotic subjects: a possible IL-6-CD44 feedback loop?
- 2007
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In: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 190:2, s. 291-7
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Journal article (peer-reviewed)abstract
- The cell-adhesion molecule CD44 likely participates in atherosclerosis development. We have shown previously that pro-inflammatory cytokines affect CD44 expression. Therefore, this work examined the role of elevated CD44 levels in human macrophages. Macrophages from human atherosclerotic subjects (n=15) showed elevated levels of CD44 transcript and protein (1.5-fold) compared to matched controls (n=15) (P=0.050 and 0.044, respectively). To test whether genetic factors influence CD44 expression, two single nucleotide polymorphisms in the CD44 gene were analyzed but these were not associated with coronary artery disease. We also examined the potential connection between plasma cytokine levels and CD44 expression. In atherosclerotic subjects, elevated CD44 expression correlates (P=0.012) with enhanced macrophage IL-6 secretion (3.13+/-2.5 pg/mL versus 0.32+/-0.16 pg/mL in controls, P=0.021). Additionally, CD44-deficient mice exhibit less circulating IL-6 than wild-type controls (9.8+/-0.7 pg/mL versus 14.3+/-0.7 pg/mL; P=0.032). Furthermore, IL-6 augments CD44 expression in primary human macrophages after 24 h (P=0.038) and 48 h (P=0.015). Taken together, our data show an IL-6-CD44 feedback loop in macrophages. Such a positive feedback loop may aggravate atherosclerosis development.
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| 4. |
- Hägg, Daniel, 1974, et al.
(author)
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Oxidized LDL induces a coordinated up-regulation of the glutathione and thioredoxin systems in human macrophages.
- 2006
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In: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 185:2, s. 282-9
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Journal article (peer-reviewed)abstract
- Using DNA microarray analysis, we found that human macrophages respond to oxidized low-density lipoprotein (oxLDL) by activating the antioxidative glutathione and thioredoxin systems. Several genes of the glutathione and thioredoxin systems were expressed at high levels in macrophages when compared to 80 other human tissues and cell types, indicating that these systems may be of particular importance in macrophages. The up-regulation of three genes in these systems, thioredoxin (P < 0.005), thioredoxin reductase 1 (P < 0.001) and glutathione reductase (P < 0.001) was verified with real-time RT-PCR, using human macrophages from 10 healthy donors. To investigate the possible role of these antioxidative systems in the development of atherosclerosis, expression levels in macrophages from 15 subjects with atherosclerosis (12 men, 3 women) and 15 matched controls (12 men, 3 women) were analyzed using DNA microarrays. Two genes in the glutathione system Mn superoxide dismutase (P < 0.05) and catalase (P < 0.05) differed in expression between the groups. We conclude that macrophage uptake of oxidized LDL induces a coordinated up-regulation of genes of the glutathione and thioredoxin systems, suggesting that these systems may participate in the cellular defense against oxidized LDL and possibly modulate the development of atherosclerosis.
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| 5. |
- Knutsen Rydberg, Ellen, 1969, et al.
(author)
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Hypoxia increases LDL oxidation and expression of 15-lipoxygenase-2 in human macrophages
- 2004
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In: Arterioscler Thromb Vasc Biol. ; 24:11, s. 2040-2045
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Macrophage-mediated oxidation of low-density lipoprotein (LDL) by enzymes, such as the lipoxygenases, is considered of major importance for the formation of oxidized LDL during atherogenesis. Macrophages have been identified in hypoxic areas in atherosclerotic plaques. METHODS AND RESULTS: To investigate the role of hypoxia in macrophage-mediated LDL oxidation, we incubated human monocyte-derived macrophages with LDL under normoxic (21% O2) or hypoxic (0% O2) conditions. The results showed that hypoxic macrophages oxidized LDL to a significantly higher extent than normoxic cells. Interestingly, the mRNA and protein expression of 15-lipoxygenase-2 (15-LOX-2) as well as the activity of this enzyme are elevated in macrophages incubated at hypoxia. Both the unspliced 15-LOX-2 and the spliced variant 15-LOX-2sv-a are found in macrophages. In addition, 15-LOX-2 was identified in carotid plaques in some macrophage-rich areas but was only expressed at low levels in nondiseased arteries. CONCLUSIONS: In summary, these observations show for the first time that 15-LOX-2 is expressed in hypoxic macrophages and in atherosclerotic plaques and suggest that 15-LOX-2 may be one of the factors involved in macrophage-mediated LDL oxidation at hypoxia.
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| 6. |
- Svensson, Per Anders, 1959, et al.
(author)
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Identification of genes predominantly expressed in human macrophages
- 2004
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In: Atherosclerosis. - : Elsevier BV. ; 177, s. 287-290
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Journal article (peer-reviewed)abstract
- Identification of cell and tissue specific genes may provide novel insights to signaling systems and functions. Macrophages play a key role in many diseases including atherosclerosis. Using DNA microarrays we compared the expression of approximately 10,000 genes in 56 human tissues and identified 23 genes with predominant expression in macrophages. The identified genes include both genes known to be macrophage specific and genes previously not well described in this cell type. Tissue distribution of two genes, liver X receptor (LXR) alpha and interleukin-1 receptor antagonist (IL1RN), was verified by real-time RT-PCR. We conclude that comparison of expression profiles from a large number of tissues can be used to identify genes that are predominantly expressed in certain tissues. Identification of novel macrophage specific genes may increase our understanding of the role of this cell in different diseases.
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| 7. |
- Svensson, Per-Arne, 1969, et al.
(author)
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Regulation and splicing of scavenger receptor class B type I in human macrophages and atherosclerotic plaques
- 2005
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In: BMC Cardiovasc Disord. - : Springer Science and Business Media LLC. - 1471-2261. ; 5
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Journal article (peer-reviewed)abstract
- BACKGROUND: The protective role of high-density lipoprotein (HDL) in the cardiovascular system is related to its role in the reverse transport of cholesterol from the arterial wall to the liver for subsequent excretion via the bile. Scavenger receptor class B type I (SR-BI) binds HDL and mediates selective uptake of cholesterol ester and cellular efflux of cholesterol to HDL. The role of SR-BI in atherosclerosis has been well established in murine models but it remains unclear whether SR-BI plays an equally important role in atherosclerosis in humans. The aim of this study was to investigate the expression of SR-BI and its isoforms in human macrophages and atherosclerotic plaques. METHODS: The effect of hypoxia and minimally modified low-density lipoprotein (mmLDL), two proatherogenic stimuli, on SR-BI expression was studied in human monocyte-derived macrophages from healthy subjects using real-time PCR. In addition, SR-BI expression was determined in macrophages obtained from subjects with atherosclerosis (n = 15) and healthy controls (n = 15). Expression of SR-BI isoforms was characterized in human atherosclerotic plaques and macrophages using RT-PCR and DNA sequencing. RESULTS: SR-BI expression was decreased in macrophages after hypoxia (p < 0.005). In contrast, SR-BI expression was increased by exposure to mmLDL (p < 0.05). There was no difference in SR-BI expression in macrophages from patients with atherosclerosis compared to controls. In both groups, SR-BI expression was increased by exposure to mmLDL (p < 0.05). Transcripts corresponding to SR-BI and SR-BII were detected in macrophages. In addition, a third isoform, referred to as SR-BIII, was discovered. All three isoforms were also expressed in human atherosclerotic plaque. Compared to the other isoforms, the novel SR-BIII isoform was predicted to have a unique intracellular C-terminal domain containing 53 amino acids. CONCLUSION: We conclude that SR-BI is regulated by proatherogenic stimuli in humans. However, we found no differences between subjects with atherosclerosis and healthy controls. This indicates that altered SR-BI expression is not a common cause of atherosclerosis. In addition, we identified SR-BIII as a novel isoform expressed in human macrophages and in human atherosclerotic plaques.
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