97 research outputs found
Catch and Release: NG2-Coated Vascular Smooth Muscle Cells Capture Lipoproteins for Macrophages
No full textThe role of the adventitia and perivascular tissue for the formation of intimal hyperplasia
No full textSymptomatic atherosclerosis is commonly treated with balloon angioplasty or bypass surgery. About 30% of the interventions will re-narrow within a year due to restenosis and graft-stenosis. Thickening of the luminal layer, the intima, is an important component in these side-effects. Smooth muscle cells (SMCs) from the media have been regarded as responsible for the formation of the intimal hyperplasia. During the last decade the outermost vessel wall layer, the adventitia, and the perivascular tissue have been recognized as additional sources for intimal SMCs. The aim of this thesis was to investigate the role of the adventitia and the perivascular tissue in the formation of intimal hyperplasia. The specific aims were to investigate 1) if intimal hyperplasia can be inhibited from the adventitial side of a vessel, 2) if the adventitia and perivascular tissue can contribute with neointimal cells and 3) if the adventitia and perivascular tissue have a dynamic relation to other cellular sources in the formation of intimal hyperplasia. We used three different animal models for intimal hyperplasia: balloon injury to the rabbit carotid artery, implantation of vein grafts in mice and artificial grafts in pigs. Intimal hyperplasia following balloon injury could be inhibited from the adventitial side by placing a silicone collar around the treated artery. An external inhibition was also achieved in mice with a plastic shielding that isolated acellular vein grafts from the perivascular tissue.We could not find any cell migration from the adventitia / the perivascular tissue into the neointima in the rabbit carotid artery. However, in vascular grafts the perivascular tissue contributed with neointimal cells in both mouse and pig. A contribution from the blood was seen in rabbit and suggested in mouse and pig. In mouse, there was a dynamic relationship between different cellular sources. The donor vein and the perivascular tissue could fully compensate each other in the neointimal formation. In rabbit, we could not find this phenomenon. The media was the main cellular source and could not be fully compensated for by other sources.The results in this thesis show that different cellular sources, with a varying degree of compensatory abilities, contribute with neointimal cells. The cellular sources and their dynamic potential must be known and considered when inhibiting intimal hyperplasia following balloon injury and implantation of vascular grafts
Treatment of hyaluronan accumulation ameliorates high-fat diet-induced insulin resistance in mice
No full textAmine Landscaping to Maximize Protein-Dye Fluorescence and Ultrastable Protein-Ligand Interaction
No full textChemical modification of proteins provides great opportunities to control and visualize
living systems. The most common way to modify proteins is reaction of their abundant
amines with N-hydroxysuccinimide (NHS) esters. Here we explore the impact of amine
number and positioning on protein-conjugate behavior using streptavidin-biotin, a central
tool for biological research. Dye-NHS modification of streptavidin severely damaged
ligand binding. We generated a streptavidin variant retaining ultrastable binding after
dye-NHS. Exploring the ideal level of dye modification, we engineered a panel bearing
1-6 amines per subunit—“amine landscaping”. Surprisingly, brightness increased as
amine number decreased, revealing extensive quenching following conventional labeling.
We ultimately selected Flavidin (Fluorophore-friendly streptavidin), combining
ultrastable ligand binding with increased brightness after conjugation. We confirmed
Flavidin’s imaging benefit, allowing more sensitive and specific cell labeling in tissues.
Flavidin should have wide application in molecular detection, providing general insight
into simultaneously optimizing behavior of both biomolecule and chemical probe
Increased Vascular Injury Reduces the Degree of Intimal Hyperplasia following Angioplasty in Rabbits
No full text<i>Background/Aims:</i> Formation of intimal hyperplasia following angioplastic procedures can lead to complications, including restenosis and accelerated atherosclerosis. The vessel wall media is a main source of neointimal cells. However, evidence suggests that there are additional cell sources, such as the adventitia. Here we investigate whether an extensive loss of vascular smooth muscle cells (VSMCs) in the media results in less intimal hyperplasia or if there is compensatory cell recruitment from the adventitia. <i>Methods:</i>A balloon catheter was pulled through the rabbit carotid artery 4 times (major injury) or 2 times (minor injury). Adventitial cells were labeled with 5-bromo-2-deoxyuridine or PKH26. <i>Results:</i>The major injury, but not the minor injury, resulted in a complete loss of VSMCs in large parts of the media and significant leukocyte infiltration. The major injury resulted in less neointima compared with the minor injury. The thinnest neointima was seen at the most injured parts of the media in the major injury group. Cell-tracking experiments showed that the media, but not the adventitia, served as a source of neointimal cells. <i>Conclusion:</i> An augmented angioplastic injury with extensive VSMC loss in rabbits reduced the degree of intimal hyperplasia. No compensatory recruitment of neointimal cells from the adventitia occurred.</jats:p
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No full textActivation of vascular smooth muscle cells (VSMCs) to migrate and proliferate is essential for the formation of intimal hyperplasia. Hence, selectively targeting activated VSMCs is a potential strategy against vaso-occlusive disorders such as in-stent restenosis, vein-graft stenosis, and transplant vasculopathy. We show that CD98 heavy chain (CD98hc) is markedly up-regulated in neointimal and cultured VSMCs, and that activated but not quiescent VSMCs require CD98hc for survival. CD98hc mediates integrin signaling and localizes amino acid transporters to the plasma membrane. SMC-specific deletion of CD98hc did not affect normal vessel morphology, indicating that CD98hc was not required for the maintenance of resident quiescent VSMCs; however, CD98hc deletion reduced intimal hyperplasia after arterial injury. Ex vivo and in vitro, loss of CD98hc suppressed proliferation and induced apoptosis in VSMCs. Furthermore, reconstitution with CD98hc mutants showed that CD98hc interaction with integrins was necessary for the survival of VSMCs. These studies establish the importance of CD98hc in VSMC proliferation and survival. Furthermore, loss of CD98hc was selectively deleterious to activated VSMCs while sparing resident quiescent VSMCs, suggesting that activated VSMCs are physiologically dependent on CD98hc, and hence, CD98hc is a potential therapeutic target in vaso-occlusive disorders
Site-specific programming of the host epithelial transcriptome by the gut microbiota
No full textBackground: The intestinal epithelium separates us from the microbiota but also interacts with it and thus affects host immune status and physiology. Previous studies investigated microbiota-induced responses in the gut using intact tissues or unfractionated epithelial cells, thereby limiting conclusions about regional differences in the epithelium. Here, we sought to investigate microbiota-induced transcriptional responses in specific fractions of intestinal epithelial cells. To this end, we used microarray analysis of laser capture microdissection (LCM)-harvested ileal and colonic tip and crypt epithelial fractions from germ-free and conventionally raised mice and from mice during the time course of colonization. Results: We found that about 10% of the host's transcriptome was microbially regulated, mainly including genes annotated with functions in immunity, cell proliferation, and metabolism. The microbial impact on host gene expression was highly site specific, as epithelial responses to the microbiota differed between cell fractions. Specific transcriptional regulators were enriched in each fraction. In general, the gut microbiota induced a more rapid response in the colon than in the ileum. Conclusions: Our study indicates that the microbiota engage different regulatory networks to alter host gene expression in a particular niche. Understanding host-microbiota interactions on a cellular level may facilitate signaling pathways that contribute to health and disease and thus provide new therapeutic strategies. RAMS GD, 1963, LABORATORY INVESTIGATION, V12, P35
The pro-atherogenic role of Intimal hyperplasia
No full textAtherosclerosis is a leading cause of mortality worldwide, and results from accumulation of plasma lipoproteins, mainly low-density lipopro-teins (LDL), in the sub-endothelial layer of the arterial wall. In this the-sis, I investigated how structural changes of the vessel wall can make the vessel more prone to developing atherosclerotic lesions.
Project 1: Accelerated atherosclerosis occurs following vascular inter-ventions, such as percutaneous coronary intervention and implantation of saphenous vein grafts. However, the cause of the accelerated athero-genesis is not known. We found that intimal hyperplasia induced by vascular interventions makes the vessel wall highly susceptible to LDL retention and accelerated atherosclerosis by a mechanism that can be targeted by glycosaminoglycan (GAG)-binding antibodies.
Project 2: Cadmium is an important risk factor for athero-sclerosis, but the underlying mechanism for how cadmium increases the risk of ather-osclerosis is unclear. We observed: (1) increased expression of perlecan and the GAG-chain modifying enzyme CHST3 in arteries following local exposure to cadmium; and (2) increased LDL-binding in proteo-glycans isolated from cells cocultured with cadmium. Finally, we showed that local cadmium exposure increased LDL retention in the arterial wall.
Project 3: Immunofluorescence microscopy is a method used to study the spatial location of proteins in tissues and cells. Here we present an enhanced multi-fluorescence setup based on condensed filter sets that are more specific for each fluorochrome and allow for a more efficient use of the light spectrum
Postprandial effects of the phosphodiesterase-5 inhibitor tadalafil in people with well-controlled Type 2 diabetes mellitus: a randomized controlled trial
No full textType 2 diabetes mellitus is a serious global health problem that is hard to treat in the long term, prompting great efforts to find new drug targets. Little attention has been paid, however, to the metabolic significance of the microcirculation in insulin-sensitive tissues, despite the fact that microvascular insulin resistance and endothelial dysfunction are closely associated and have been shown to precede Type 2 diabetes [1]. Endothelial nitric oxide plays a major role in mediating the beneficial effects of insulin on capillary recruitment and muscle glucose uptake [2] and in suppression of inflammatory pathways, including those activated by a high-fat diet [3]. This article is protected by copyright. All rights reserved
Catechol-O-Methyltransferase Is Dispensable for Vascular Protection by Estradiol in Mouse Models of Atherosclerosis and Neointima Formation
No full textEstradiol is converted to the biologically active metabolite 2-methoxyestradiol via the activity of the enzyme catechol-O-methyltransferase (COMT). Exogenous administration of both estradiol and 2-methoxyestradiol reduces experimental atherosclerosis and neointima formation, and COMT-dependent formation of 2-methoxyestradiol likely mediates the antimitogenic effect of estradiol on smooth muscle cells in vitro. This study evaluated whether 2-methoxyestradiol mediates the vasculoprotective actions of estradiol in vivo. Wild-type (WT) and COMT knockout (COMTKO) mice on an apolipoprotein E-deficient background were gonadectomized and treated with estradiol or placebo. Exogenous estradiol reduced atherosclerotic lesion formation in both females (WT, −78%; COMTKO, −82%) and males (WT, −48%; COMTKO, −53%) and was equally effective in both genotypes. We further evaluated how exogenous estradiol affected neointima formation after ligation of the carotid artery in ovariectomized female mice; estradiol reduced intimal hyperplasia to a similar extent in both WT (−80%) and COMTKO (−77%) mice. In ovarian-intact female COMTKO mice, atherosclerosis was decreased (−25%) compared with WT controls. In conclusion, the COMT enzyme is dispensable for vascular protection by exogenous estradiol in experimental atherosclerosis and neointima formation in vivo. Instead, COMT deficiency in virgin female mice with intact endogenous production of estradiol results in relative protection against atherosclerosis.</jats:p
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