| 1. |
- Basic, Vladimir Tomislav, et al.
(author)
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Exposure to cigarette smoke induces overexpression of von Hippel-Lindau tumor suppressor in mouse skeletal muscle
- 2012
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In: American Journal of Physiology - Lung cellular and Molecular Physiology. - Bethesda, USA : American Physiological Society. - 1040-0605 .- 1522-1504. ; 303:6, s. L519-L527
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Journal article (peer-reviewed)abstract
- Cigarette smoke (CS) is a well established risk factor in the development of chronic obstructive pulmonary disease (COPD). In contrast, the extent to which CS exposure contributes to the development of the systemic manifestations of COPD, such as skeletal muscle dysfunction and wasting remains largely unknown. Decreased skeletal muscle capillarization has been previously reported in early stages of COPD and might play an important role in the development of COPD-associated skeletal muscle abnormalities. To investigate the effects of chronic CS exposure on skeletal muscle capillarization and exercise tolerance a mouse model of CS exposure was used. The129/SvJ mice were exposed to CS for 6 months, and the expression of putative elements of the hypoxia-angiogenic signaling cascade as well as muscle capillarization were studied. Additionally, functional tests assessing exercise tolerance/endurance were performed in mice. Compared to controls, skeletal muscles from CS-exposed mice exhibited significantly enhanced expression of von Hippel-Lindau tumor suppressor (VHL), ubiquitin-conjugating enzyme E2D1 (UBE2D1) and prolyl hydroxylase-2 (PHD2). In contrast, hypoxia-inducible factor-1 (HIF1-α) and vascular endothelial growth factor (VEGF) expression was reduced. Furthermore, reduced muscle fiber cross-sectional area, decreased skeletal muscle capillarization, and reduced exercise tolerance were also observed in CS-exposed animals. Taken together, the current results provide evidence linking chronic CS exposure and induction of VHL expression in skeletal muscles leading towards impaired hypoxia-angiogenesis signal transduction, reduced muscle fiber cross-sectional area and decreased exercise tolerance.
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| 2. |
- Basic, Vladimir T., 1982-, et al.
(author)
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TNF stimulation induces VHL overexpression and impairs angiogenic potential in skeletal muscle myocytes
- 2014
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In: International Journal of Molecular Medicine. - : Spandidos Publications. - 1107-3756 .- 1791-244X. ; 34:1, s. 228-236
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Journal article (peer-reviewed)abstract
- Decreased skeletal muscle capillarization is considered to significantly contribute to the development of pulmonary cachexia syndrome (PCS) and progressive muscle wasting in several chronic inflammatory diseases, including chronic obstructive pulmonary disease (COPD). It is unclear to which extent the concurrent presence of systemic inflammation contributes to decreased skeletal muscle capillarization under these conditions. The present study was designed to examine in vitro the effects of the pro-inflammatory cytokine, tumor necrosis factor (TNF), on the regulation of hypoxia-angiogenesis signal transduction and capillarization in skeletal muscles. For this purpose, fully differentiated C2C12 skeletal muscle myocytes were stimulated with TNF and maintained under normoxic or hypoxic conditions. The expression levels of the putative elements of the hypoxia-angiogenesis signaling cascade were examined using qPCR, western blot analysis and immunofluorescence. Under normoxic conditinos, TNF stimulation increased the protein expression of anti-angiogenic von-Hippel Lindau (VHL), prolyl hydroxylase (PHD)2 and ubiquitin conjugating enzyme 2D1 (Ube2D1), as well as the total ubiquitin content in the skeletal muscle myocytes. By contrast, the expression levels of hypoxia-inducible factor 1‑α (HIF1-α) and those of its transcriptional targets, vascular endothelial growth factor (VEGF)A and glucose transporter 1 (Glut1), were markedly reduced. In addition, hypoxia increased the expression of the VHL transcript and further elevated the VHL protein expression levels in C2C12 myocytes following TNF stimulation. Consequently, an impaired angiogenic potential was observed in the TNF-stimulated myocytes during hypoxia. In conclusion, TNF increases VHL expression and disturbs hypoxia-angiogenesis signal transduction in skeletal muscle myocytes. The current findings provide a mechanism linking systemic inflammation and impaired angiogenesis in skeletal muscle. This is particularly relevant to further understanding the mechanisms mediating muscle wasting and cachexia in patients with chronic inflammatory diseases, such as COPD.
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| 3. |
- Bilbija, Dusan, et al.
(author)
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Expression of retinoic acid target genes in coronary artery disease
- 2014
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In: International Journal of Molecular Medicine. - Athens, Greece : Spandidos Publications. - 1107-3756 .- 1791-244X. ; 33:3, s. 677-86
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Journal article (peer-reviewed)abstract
- Coronary atherosclerosis can lead to myocardial infarction, and secondarily to post-infarct remodelling and heart failure. Retinoic acid (RA) influences cell proliferation. We hypothesized that RA could influence gene expression and proliferation of cardiovascular cells. Left ventricular biopsies from patients with end-stage heart failure due to coronary artery disease (CAD) or dilated cardiomyopathy were investigated for the content of RA metabolites using liquid chromatography mass spectrometry (LC-MS/MS), and compared with healthy donors. All-trans retinoic acid (ATRA) was increased in the hearts of CAD patients. Gene expression (quantitative PCR) of RA target genes was not influenced in failing hearts, but was increased in the hearts of patients with CAD undergoing open heart surgery. The expression of RA target genes was increased in atherosclerotic lesions from carotid arteries compared to healthy arteries. Stimulation of cardiomyocytes, cardiofibroblasts, smooth muscle cells and endothelial cells with ATRA increased the gene expression of the key enzymes. Cardiofibroblast and smooth muscle cell proliferation were reduced by ATRA, which increased endothelial cell proliferation. Coronary artery disease leads to increased expression of RA target genes. ATRA accumulated in the failing human heart. All investigated cell types present in the heart had induced expression of RA target genes when stimulated with ATRA, which also influenced cell proliferation.
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| 4. |
- Bilbija, Dusan, et al.
(author)
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Retinoic acid signalling is activated in the postischemic heart and may influence remodelling
- 2012
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In: PLOS ONE. - San Francisco, USA : Public Library of Science. - 1932-6203. ; 7:9
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Journal article (peer-reviewed)abstract
- Background: All-trans retinoic acid (atRA), an active derivative of vitamin A, regulates cell differentiation, proliferation and cardiac morphogenesis via transcriptional activation of retinoic acid receptors (RARs) acting on retinoic acid response elements (RARE).We hypothesized that the retinoic acid (RA) signalling pathway is activated in myocardial ischemia and postischemic remodelling.Methods and Findings: Myocardial infarction was induced through ligating the left coronary artery in mice. In vivo cardiac activation of the RARs was measured by imaging RARE-luciferase reporter mice, and analysing expression of RAR target genes and proteins by real time RT-PCR and western blot. Endogenous retinoids in postinfarcted hearts were analysed by triple-stage liquid chromatography/tandem mass spectrometry. Cardiomyocytes (CM) and cardiofibroblasts (CF) were isolated from infarcted and sham operated RARE luciferase reporter hearts and monitored for RAR activity and expression of target genes. The effect of atRA on CF proliferation was evaluated by EdU incorporation. Myocardial infarction increased thoracic RAR activity in vivo (p<0.001), which was ascribed to the heart through ex vivo imaging (p = 0.002) with the largest signal 1 week postinfarct. This was accompanied by increased cardiac gene and protein expression of the RAR target genes retinol binding protein 1 (p = 0.01 for RNA, p = 0,006 for protein) and aldehyde dehydrogenase 1A2 (p = 0.04 for RNA, p = 0,014 for protein), while gene expression of cytochrome P450 26B1 was downregulated (p = 0.007). Concomitantly, retinol accumulated in the infarcted zone (p = 0.02). CM and CF isolated from infarcted hearts had higher luminescence than those from sham operated hearts (p = 0.02 and p = 0.008). AtRA inhibited CF proliferation in vitro (p = 0.02).Conclusions: The RA signalling pathway is activated in postischemic hearts and may play a role in regulation of damage and repair during remodelling.
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| 5. |
- El Marghani, Ahmed M., et al.
(author)
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High MAPK p38 activity and low level of IL-10 in intermittent claudication as opposed to stable angina
- 2010
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In: International Journal of Angiology. - Torino : Minerva Medica. - 0392-9590 .- 1827-1839. ; 29:4, s. 331-337
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Journal article (peer-reviewed)abstract
- AIM:The aim of the present pilot study was to relate the activity of MAPK p38 with the levels of pro- and anti-inflammatory cytokines in a small cohort of patients with either stable angina (N=5) or intermittent claudication (N=5) compared to healthy controls (N=10).METHODS:The activity of MAPK p38 was determined in peripheral blood mononuclear cells, isolated from whole blood by western blot using phospho-specific anti-MAPK p38 antibodies. Cytokine levels of 11 pro- and anti-inflammatory cytokines were determined from the serum using flow cytometry.RESULTS:We found a significant elevation of the MAPK p38 activity in the intermittent claudication group (P=0.0027) compared with the healthy control group whereas the stable angina group showed similar MAPK p38 activity as the healthy control group. The IL-10 level in serum found in the stable angina group was significantly higher compared with both the healthy control group (P=0.0116) and the intermittent claudication group (P=0.0317).CONCLUSION:Our results imply that there is a casual relationship between increased levels of the anti-inflammatory cytokines IL-10 and IL-4 and the activity of the MAPK p38. Possibly has IL-10 a protective role that down-regulates the activity of MAPK p38 and thereby further inflammatory processes in stable angina patients.
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| 6. |
- Elmabsout, Ali Ateia, et al.
(author)
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Cloning and Functional Studies of a Splice Variant of CYP26B1 Expressed in Vascular Cells
- 2012
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In: Plos One. - San Francisco, USA : Public Library of Science (PLoS). - 1932-6203. ; 7:5
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Journal article (peer-reviewed)abstract
- Background: All-trans retinoic acid (atRA) plays an essential role in the regulation of gene expression, cell growth and differentiation and is also important for normal cardiovascular development but may in turn be involved in cardiovascular diseases, i.e. atherosclerosis and restenosis. The cellular atRA levels are under strict control involving several cytochromes P450 isoforms (CYPs). CYP26 may be the most important regulator of atRA catabolism in vascular cells. The present study describes the molecular cloning, characterization and function of atRA-induced expression of a spliced variant of the CYP26B1 gene. Methodology/Principal Findings: The coding region of the spliced CYP26B1 lacking exon 2 was amplified from cDNA synthesized from atRA-treated human aortic smooth muscle cells and sequenced. Both the spliced variant and full length CYP26B1 was found to be expressed in cultured human endothelial and smooth muscle cells, and in normal and atherosclerotic vessel. atRA induced both variants of CYP26B1 in cultured vascular cells. Furthermore, the levels of spliced mRNA transcript were 4.5 times higher in the atherosclerotic lesion compared to normal arteries and the expression in the lesions was increased 20-fold upon atRA treatment. The spliced CYP26B1 still has the capability to degrade atRA, but at an initial rate one-third that of the corresponding full length enzyme. Transfection of COS-1 and THP-1 cells with the CYP26B1 spliced variant indicated either an increase or a decrease in the catabolism of atRA, probably depending on the expression of other atRA catabolizing enzymes in the cells. Conclusions/Significance: Vascular cells express the spliced variant of CYP26B1 lacking exon 2 and it is also increased in atherosclerotic lesions. The spliced variant displays a slower and reduced degradation of atRA as compared to the full-length enzyme. Further studies are needed, however, to clarify the substrate specificity and role of the CYP26B1 splice variant in health and disease.
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| 7. |
- Elmabsout, Ali Ateia, 1977-
(author)
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CYP26B1 as regulator of retinoic acid in vascular cells and atherosclerotic lesions
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Cardiovascular disease (CVD), currently the most common cause of morbidity and mortality worldwide, is caused mainly by atherosclerosis. Atherosclerosis is a chronic multifocal, immunoinflammatory, fibroproliferative disease of medium and large arteries. Atherosclerotic lesions and vascular cells express different genes, among these are genes regulated by retinoic acid. Retinoids have pleiotropic effects and are able to modulate gene expression involved in growth, function and adaptation. During atherosclerosis development, there is endothelial perturbation, lipid accumulation, attraction of immune cells, smooth muscle cell migration and extracellular matrix remodeling and eventually fibrous cap formation which results in plaques. Retinoids have been demonstrated to either inhibit or modulate the above processes, resulting in amelioration of atherosclerosis. So far, retinoids are known to have impact on cellular processes in SMC, vascular injury and atherosclerosis. However, little is known about catabolism of retinoids in vascular cells and lesions and the effects of alteration of retinoic catabolizing enzymes on retinoids’ status. Therefore, we investigated the expression of Cytochrome P450 26 (CYP26) which is thought to be dedicated to retinoid catabolism. In vascular SMCs and atherosclerotic lesions, we found that CYP26B1 was the only member of the CYP26 family expressed, and it was highly inducible by atRA. Our data revealed that blocking CYP26B1 by chemical inhibition, or by targeted siRNA knock-down, resulted in significantly increased cellular retinoid levels. This indicates that CYP26B1 is an important modulator of endogenous retinoic acid levels. Therefore, we studied the effect of the CYP26B1 nonsynonymous polymorphism rs224105 on retinoic acid availability and found that the minor allele was associated with an enhanced retinoic acid catabolism rate and also with a slightly larger area of atherosclerotic lesions. The expression of CYP26B1 in human atherosclerotic lesions was localized to macrophage rich areas, suggesting retinoic acid activity in macrophages. Furthermore, we demonstrated that a CYP26B1 splice variant, that lack exon two, is expressed in vascular cells and in vessels walls. It is functional, with a reduced catabolic activity to around 70%, inducible by atRA in vascular cells and expressed 4.5 times more in atherosclerotic lesions compared to normal arteries. Moreover, the statins simvastatin and rosuvastatin reduced CYP26B1 mediated atRA catabolism in a concentration-dependent manner, and in vascular cells increased the mRNA expression of the atRA-responsive genes CYP26B1 and RARβ. This could lead to statins indirectly augmenting retinoic acid action in vascular cells which mimic statins roles. In conclusion, CYP26B1 is a major retinoic acid modulator in vascular cells and atherosclerotic lesions. Blocking of CYP26B1 could provide an advantageous therapeutic alternative to exogenous retinoid administration for treatment of vascular disorders.
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| 8. |
- Elmabsout, Ali, et al.
(author)
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Cloning and functional studies of a splice variant of CYP26B1 : a cellular storage protein for all-trans retinoic acid
- 2010
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In: In Vivo. - 0258-851X .- 1791-7549. ; 24:3, s. 345-346
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Journal article (peer-reviewed)abstract
- BackgroundAll-trans retinoic acid (atRA) plays an essential role in the regulation of gene expression, cell growth and differentiation and is also important for normal cardiovascular development but may in turn be involved in cardiovascular diseases, i.e. atherosclerosis and restenosis. The cellular atRA levels are under strict control involving several cytochromes P450 isoforms (CYPs). CYP26 may be the most important regulator of atRA catabolism in vascular cells. The present study describes the molecular cloning, characterization and function of atRA-induced expression of a spliced variant of the CYP26B1 gene.Methodology/Principal FindingsThe coding region of the spliced CYP26B1 lacking exon 2 was amplified from cDNA synthesized from atRA-treated human aortic smooth muscle cells and sequenced. Both the spliced variant and full length CYP26B1 was found to be expressed in cultured human endothelial and smooth muscle cells, and in normal and atherosclerotic vessel. atRA induced both variants of CYP26B1 in cultured vascular cells. Furthermore, the levels of spliced mRNA transcript were 4.5 times higher in the atherosclerotic lesion compared to normal arteries and the expression in the lesions was increased 20-fold upon atRA treatment. The spliced CYP26B1 still has the capability to degrade atRA, but at an initial rate one-third that of the corresponding full length enzyme. Transfection of COS-1 and THP-1 cells with the CYP26B1 spliced variant indicated either an increase or a decrease in the catabolism of atRA, probably depending on the expression of other atRA catabolizing enzymes in the cells.Conclusions/SignificanceVascular cells express the spliced variant of CYP26B1 lacking exon 2 and it is also increased in atherosclerotic lesions. The spliced variant displays a slower and reduced degradation of atRA as compared to the full-length enzyme. Further studies are needed, however, to clarify the substrate specificity and role of the CYP26B1 splice variant in health and disease.
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| 9. |
- Fransén, Karin, 1973-, et al.
(author)
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Polymorphism in the retinoic acid metabolizing enzyme CYP26B1 and the development of Crohn's disease
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8, s. e72739-
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Journal article (peer-reviewed)abstract
- Several studies suggest that Vitamin A may be involved in the pathogenesis of inflammatory bowel disease (IBD), but the mechanism is still unknown. Cytochrome P450 26 B1 (CYP26B1) is involved in the degradation of retinoic acid and the polymorphism rs2241057 has an elevated catabolic function of retinoic acid, why we hypothesized that the rs2241057 polymorphism may affect the risk of Crohn's disease (CD) and Ulcerative Colitis (UC). DNA from 1378 IBD patients, divided into 871 patients with CD and 507 with UC, and 1205 healthy controls collected at Örebro University Hospital and Karolinska University Hospital were analyzed for the CYP26B1 rs2241057 polymorphism with TaqMan® SNP Genotyping Assay followed by allelic discrimination analysis. A higher frequency of patients homozygous for the major (T) allele was associated with CD but not UC compared to the frequency found in healthy controls. A significant association between the major allele and non-stricturing, non-penetrating phenotype was evident for CD. However, the observed associations reached borderline significance only, after correcting for multiple testing. We suggest that homozygous carriers of the major (T) allele, relative to homozygous carriers of the minor (C) allele, of the CYP26B1 polymorphism rs2241057 may have an increased risk for the development of CD, which possibly may be due to elevated levels of retinoic acid. Our data may support the role of Vitamin A in the pathophysiology of CD, but the exact mechanisms remain to be elucidated.
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| 10. |
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