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Biomedical subjects

Alain Tedgui

Publications and source records attributed to Alain Tedgui.

At least 37 records · Page 2Linked to original sources
PubMed2004

Evidence for altered interleukin 18 (IL)-18 pathway in human heart failure.

Interleukin (IL)-18 is the interferon-gamma-inducing factor and has potent proinflammatory activities. IL-18 has been recently implicated in atherosclerotic plaque instability and myocardial ischemia-reperfusion injury. However, it is unknown whether IL-18 expression is increased in human myocardium or if it has any role in heart failure. We analyzed the expression of IL-18, its receptor IL-18Ralpha, and its endogenous inhibitor, IL-18 binding protein (IL-18BP) in myocardial tissue from patients with end-stage heart failure (ischemic or dilated cardiomyopathy) and controls by use of quantitative real-time reverse transcriptase polymerase chain reaction, Western blot or immunohistochemical techniques. Plasma levels of IL-18 were also determined in 48 patients with heart failure. IL-18 mRNA and protein levels were up-regulated in the myocardium of patients with ischemic cardiomyopathy. Both ischemic and dilated myocardium showed increased IL-18Ralpha levels, suggesting potential biological effects. In addition, mRNA levels of IL-18 BP were down-regulated in the failing myocardium. Finally, plasma IL-18 levels were significantly elevated in patients with heart failure and were higher in those who died at follow-up than in survivors. The results suggest a potential role for the immunoinflammatory IL-18 signaling pathway in the pathophysiology of heart failure and identify novel therapeutic targets for future testing.

Cardiac Output, Low↗
PubMed2004

Leukocyte-derived interleukin 10 is required for protection against atherosclerosis in low-density lipoprotein receptor knockout mice.

BACKGROUND: Atherosclerosis is an immunoinflammatory disease. Here we examined the role of leukocyte-derived interleukin 10 (IL-10) on advanced atherosclerosis development in low-density lipoprotein receptor knockout (LDLr-/-) mice. METHODS AND RESULTS: Bone marrow cells harvested from C57BL/6 IL-10-/- and IL-10+/+ mice were transplanted into irradiated male LDLr-/- mice. Four weeks after transplantation, mice were fed a high-fat cholate-free diet for 14 weeks. Despite no differences in weights, serum total, and HDL-cholesterol levels between the 2 groups, IL-10 deficiency in leukocytes induced a >2-fold increase in lesion development in the thoracic aorta compared with controls. We also found a significant 35% increase in aortic root lesion area of IL-10-/- mice compared with IL-10+/+ mice. Furthermore, IL-10 deficiency led to a marked increase in lymphocyte and macrophage accumulation associated with a significant reduction in collagen accumulation. Finally, transfer of IL-10-/- splenocytes to LDLr-/- mice resulted in a 3-fold increase in lesion size in the aortic sinus compared with mice transplanted with IL-10+/+ splenocytes. CONCLUSIONS: IL-10 expressed by leukocytes prevents exaggerated advanced atherosclerosis development and plays a critical role in modulation of cellular and collagen plaque composition, at least in part, through a modulation of the systemic immune response.

Animals↗
PubMed2004

Pressure-induced matrix metalloproteinase-9 contributes to early hypertensive remodeling.

BACKGROUND: High blood pressure causes a change in vascular wall structure involving altered extracellular matrix composition, but how this process occurs is not fully understood. METHODS AND RESULTS: Using mouse carotid arteries maintained in organ culture for 3 days, we detected increased gelatin zymographic activity of matrix metalloproteinase (MMP)-2 (168+/-13%, P<0.05) in vessels kept at low intraluminal pressure (10 mm Hg) compared with vessels at 80 mm Hg (100%), whereas in vessels maintained at high pressure (150 mm Hg), both MMP-2 and MMP-9 activity was induced (182+/-32%, P<0.05, and 194+/-21%, P<0.01, respectively). MMPs were detected in endothelial and smooth muscle cells by immunohistochemistry and in situ gelatin zymography. In vessels at 150 mm Hg, MMP activation was associated with a shift in the pressure-diameter curve toward greater distensibility (P<0.01) compared with vessels at 80 mm Hg. However, distensibility was not altered in vessels at 10 mm Hg, in which only activated MMP-2 was detected. The role of MMPs in high pressure-induced vessel distensibility was confirmed by use of the MMP inhibitor FN-439, which prevented the shift in the pressure-diameter relationship. Furthermore, in carotid arteries from MMP-9-deficient mice, the pressure-dependent increase in MMP-2 and in situ gelatinolytic activity were maintained, but the upward shift in the pressure-diameter curve was abolished. CONCLUSIONS: MMP-9 seems to play a key role in the early stages of hypertensive vascular remodeling.

Animals↗
PubMed2004

The "CholesteROR" protective pathway in the vascular system.

Retinoic acid receptor-related Orphan Receptor alpha (RORalpha) is a member of the nuclear hormone receptor superfamily. RORalpha has long been considered as a constitutive activator of transcription in the absence of exogenous ligand; however, cholesterol has recently been identified as a natural ligand of RORalpha. The spontaneous staggerer (sg/sg) mutation is a deletion in the Rora gene that prevents the translation of the ligand-binding domain (LBD), leading to the loss of RORalpha activity. The homozygous Rora(sg/sg) mutant mouse, of which the most obvious phenotype is ataxia associated with cerebellar degeneration, also displays a variety of other phenotypes, including several vascular ones; in particular, dysfunction of smooth muscle cells and enhanced susceptibility to atherosclerosis. Moreover, RORalpha appears to participate in the regulation of plasma cholesterol levels, and has been shown to positively regulate apolipoprotein (apo)A-I and apoC-III gene expression. Yet its activity is regulated by cholesterol itself, making RORalpha an intracellular cholesterol target.

Animals↗
PubMed2004

Plasticity of human adipose lineage cells toward endothelial cells: physiological and therapeutic perspectives.

BACKGROUND: Adipose tissue development and remodeling are closely associated with the growth of vascular network. We hypothesized that adipose tissue may contain progenitor cells with angiogenic potential and that therapy based on adipose tissue-derived progenitor cells administration may constitute a promising cell therapy in patients with ischemic disease. METHODS AND RESULTS: In mice, cultured stromal-vascular fraction (SVF) cells from adipose tissue have a great proangiogenic potential, comparable to that of bone marrow mononuclear cells in the mouse ischemic hindlimb model. Similarly, cultured human SVF cells differentiate into endothelial cells, incorporate into vessels, and promote both postischemic neovascularization in nude mice and vessel-like structure formation in Matrigel plug. In vitro, these cells represent a homogeneous population of CD34- and CD13-positive cells, which can spontaneously express the endothelial cell markers CD31 and von Willebrand factor when cultured in semisolid medium. Interestingly, dedifferentiated mature human adipocytes have the potential to rapidly acquire the endothelial phenotype in vitro and to promote neovascularization in ischemic tissue and vessel-like structure formation in Matrigel plug, suggesting that cells of endothelial and adipocyte phenotypes may have a common precursor. CONCLUSIONS: This study demonstrates, for the first time, that adipocytes and endothelial cells have a common progenitor. Such adipose lineage cells participate in vascular-like structure formation in Matrigel plug and enhance the neovascularization reaction in ischemic tissue. These results also highlight the concept that adipose lineage cells represent a suitable new cell source for therapeutic angiogenesis in ischemic disease.

Adipocytes↗
PubMed2004

[Apoptosis and acute coronary syndromes].

Atherosclerosis is an inflammatory disease of the arterial wall. Ischemic manifestations of atherosclerosis are mainly due to thrombus formation upon a superficially eroded (denudation of luminal endothelium, 40% of cases) or deeply ruptured (fibrous cap rupture, 60% of cases) plaques. Recent studies have unraveled potentially critical roles for both inflammatory and apoptotic processes in plaque destabilization leading to thrombus formation. Pro-inflammatory mediators have been particularly implicated in the loss of smooth muscle cell and the promotion of collagen degradation that are responsible for fibrous cap rupture, whereas apoptosis has been identified as one of the major determinants of plaque thrombogenicity.

Acute Disease↗
PubMed2004

[Shear and signal transduction in the endothelial cell].

Blood vessels are permanently subjected to mechanical forces in the form of stretch and shear stress. Any alterations in the hemodynamic environment invariably produce transformations in the vessel wall that will aim to accommodate the new conditions and to ultimately restore basal levels of mechanical forces. Many receptors, present on the surface of endothelial cells, allow vessels to detect subtle changes in shear stress. Inside the cells, cytoskeletal proteins transmit and modulate the tension between integrins, focal adhesion sites, and the extracellular matrix. Besides inducing structural modifications, mechanical forces lead to changes in the ionic composition of cells, mediated by ion channels, stimulate various membrane receptors, and induce complex biochemical cascades. Many intracellular pathways such as the MAP kinase cascade are activated by shear stress and initiate via sequential phosphorylations the activation of transcription factors and subsequent gene expression. Thus, by purely local mechanisms, blood vessels are capable of true autonomic regulation which enables them to adapt to their mechanical environment.

Animals↗
PubMed2004

Immunomodulation to combat atherosclerosis: the potential role of immune regulatory cells.

Atherosclerosis is an inflammatory disease of the arterial wall that carries an important socio-economic burden. The available data strongly suggest that both innate and adaptive immuno-inflammatory mechanisms are the major determinants of plaque complications (called instability). Therefore, most of the important advances in the comprehension of the mechanisms of atherosclerosis came from studies that aimed at the elucidation of the critical components involved in the modulation of the immuno-inflammatory response in experimental models of atherosclerosis. As the T helper (Th)1-driven immune response has been consistently shown to promote atherosclerosis, the general belief is that immunomodulation through Th2 may be suitable to halt the disease process. Here, a novel view of the immuno-inflammatory response in atherosclerosis is presented, in which the natural and/or adaptive regulatory responses modulate both Th1 and Th2 responses, and play a central role in counteracting disease initiation and progression.

Animals↗
PubMed2003

Transplantation of bone marrow-derived mononuclear cells in ischemic apolipoprotein E-knockout mice accelerates atherosclerosis without altering plaque composition.

BACKGROUND: Bone marrow-derived mononuclear cells (BM-MNCs) enhance postischemic neovascularization, and their therapeutic use is currently under clinical investigation. We evaluated the safety of BM-MNC-based therapy in the setting of atherosclerosis. METHODS AND RESULTS: Apolipoprotein E (apoE)-knockout (KO) mice were divided into 4 groups: 20 nonischemic mice receiving intravenous injection of either saline (n=10) or 10(6) BM-MNCs from wild-type animals (n=10) and 20 mice with arterial femoral ligature receiving intravenous injection of either saline (n=10) or 10(6) BM-MNCs from wild-type animals (n=10) at the time of ischemia induction. Animals were monitored for 4 additional weeks. Atherosclerosis was evaluated in the aortic sinus. BM-MNC transplantation improved tissue neovascularization in ischemic hind limbs, as revealed by the 210% increase in angiography score (P<0.0001), the 33% increase in capillary density (P=0.01), and the 65% increase in tissue Doppler perfusion score (P=0.0002). Hindlimb ischemia without BM-MNC transplantation or BM-MNC transplantation without ischemia did not affect atherosclerotic plaque size. However, transplantation of 10(6) BM-MNCs into apoE-KO mice with hindlimb ischemia induced a significant 48% to 72% increase in lesion size compared with the other 3 groups (P=0.0025), despite similar total cholesterol levels. Transplantation of 10(5) BM-MNCs produced similar results, whereas transplantation of 10(6) apoE-KO-derived BM-MNCs had neither proangiogenic nor proatherogenic effects. There was no difference in plaque composition between groups. CONCLUSIONS: BM-MNC therapy is unlikely to affect atherosclerotic plaque stability in the short term. However, it may promote further atherosclerotic plaque progression in an ischemic setting.

Animals↗
PubMed2003

Rho-associated protein kinase contributes to early atherosclerotic lesion formation in mice.

Members of the Rho family of small GTPases have been recently implicated in inflammatory signaling. We examined the effect of in vivo inhibition of Rho kinase on atherogenesis in mice. Low-density lipoprotein receptor (LDLR) knockout (KO) mice fed a cholate-free high-fat diet received daily intraperitoneal injection of saline (n=8, control group) or Y-27632 (30 mg/kg, n=9), a specific Rho kinase inhibitor. After 9 weeks, Y-27632 treatment resulted in significant in vivo inhibition of Rho kinase activity (P=0.004). Body weights, arterial blood pressures, and plasma cholesterol levels were comparable in both groups. Atherosclerotic lesion size in the aortic sinus and thoracic aorta of mice treated with Y-27632 was reduced by respectively 35% and 29% in comparison with the saline-treated animals (P=0.006 and P=0.03, respectively). This was associated with a significant reduction in T lymphocyte accumulation (P=0.035) and expression of p65 subunit of NF-kappaB within plaques (P<0.05). In vitro, treatment with Y-27632 inhibited p65 phosphorylation and degradation of IkappaBalpha in mouse peritoneal macrophages and significantly inhibited concanavalin A-induced proliferation of spleen-derived T cells (P<0.001). In conclusion, inhibition of Rho kinase significantly limits early atherosclerotic plaque development in the LDLR KO mice. This study identifies Rho kinase inhibitors as potential candidates for the treatment of atherosclerosis.

Amides↗
PubMed2003

Specific abrogation of transforming growth factor-beta signaling in T cells alters atherosclerotic lesion size and composition in mice.

A large body of evidence supports a role for proinflammatory mediators in atherosclerotic disease progression and instability. However, only few endogenous mechanisms have been suggested that could alter disease progression. One such mechanism is thought to be mediated by transforming growth factor beta (TGF-beta). Transgenic mice that express a dominant-negative TGF-beta receptor type II under a T-cell-specific promoter were generated. Bone marrow transplantation from transgenic mice into irradiated low density lipoprotein receptor knock-out (LDLr KO) mice, subsequently fed an atherogenic diet, resulted in T-cell-specific blockade of TGF-beta signaling in the recipient mice and increased differentiation of T cells toward both T helper 1 (Th1) and Th2 phenotypes. These mice showed a significant decrease in atherosclerotic lesion size in the aortic sinus compared with mice receiving transplants with the wild-type bone marrow. Atherosclerotic plaques of mice receiving transplants with the transgenic bone marrow showed increased T-cell infiltration and expression of major histocompatability complex (MHC) class II, along with a decrease in smooth muscle cell and collagen content, a plaque phenotype that is potentially vulnerable to rupture. These results identify for the first time an important role for specific and selective T-cell-TGF-beta signaling in atherosclerosis.

Animals↗
PubMed2003

Induction of a regulatory T cell type 1 response reduces the development of atherosclerosis in apolipoprotein E-knockout mice.

BACKGROUND: T helper type 1 (Th1) response plays a permissive role in atherosclerosis. We hypothesized that adoptive transfer of a novel subtype of T lymphocytes called regulatory T cells type 1 (Tr1) would inhibit Th1 responses by inducing a bystander immune suppression and therefore limit the development of atherosclerosis. METHODS AND RESULTS: Clones of ovalbumin (OVA)-specific Tr1 cells expanded in vitro were administered intraperitoneally (106 cells per mouse) with their cognate antigen (50 microg of OVA subcutaneously in complete Freund's adjuvant [CFA]) to female apolipoprotein E-knockout mice. A group of mice received only (OVA/CFA) immunization without Tr1 cells. Two other control groups received no immunization and were injected with either Tr1 cells or saline. After 9 weeks of treatment, mice injected with (OVA/CFA)+OVA-specific Tr1 cells showed a significant decrease in Th1 responses, as revealed by a decrease in OVA-specific IgG2a serum levels (P<0.0001), a decrease in the production of interferon-gamma (P<0.001), and an increase in interleukin-10 production (P<0.001) by cultured spleen and lymph T cells compared with controls. In addition, cytokine production by concanavalin A-stimulated spleen cells showed a clear switch to a regulatory immune response in mice treated with (OVA/CFA)+Tr1. This was associated with a significant reduction in atherosclerotic lesion size in both the thoracic aorta and aortic sinus of mice treated with (OVA/CFA)+Tr1 compared with controls (P=0.002 to P<0.0001). Plaques of mice injected with (OVA/CFA)+Tr1 showed significantly lower accumulation of macrophages and T cells than plaques of control mice. CONCLUSIONS: Tr1-type regulatory immune response reduces the development of experimental atherosclerosis.

Adoptive Transfer↗
PubMed2003

Bone marrow transplantation reveals the in vivo expression of the mitochondrial uncoupling protein 2 in immune and nonimmune cells during inflammation.

The mitochondrial uncoupling protein 2 (UCP2) is expressed in spleen, lung, intestine, white adipose tissue, and immune cells. Bone marrow transplantation in mice was used to assess the contribution of immune cells to the expression of UCP2 in basal condition and during inflammation. Immune cells accounted for the total amount of UCP2 expression in the spleen, one-third of its expression in the lung, and did not participate in its expression in the intestine. LPS injection stimulated UCP2 expression in lung, spleen, and intestine in both immune and non-immune cells. Successive injections of LPS and dexamethasone or N-acetyl-cysteine prevented the induction of UCP2 in all three tissues, suggesting that oxygen free radical generation plays a role in UCP2 regulation. Finally, both previous studies and our data show that there is down-regulation of UCP2 in immune cells during their activation in the early stages of the LPS response followed by an up-regulation in UCP2 during the later stages to protect all cells against oxidative stress.

Acetylcysteine↗
PubMed2003

Pressure-induced vascular activation of nuclear factor-kappaB: role in cell survival.

The effects of mechanical factors on nuclear factor (NF)-kappaB activation and its potential functional roles have been very little explored in the intact vessel. Thus, we chose to study the regulation of NF-kappaB by intraluminal pressure using an organ culture model of mouse carotid arteries maintained at 80 or 150 mm Hg during 24 hours. Gel shift analysis revealed an increase in the DNA-binding capacity of NF-kappaB in vessels at high pressure compared with vessels at normal pressure (304+/-49%; P<0.001). This coincided with reduced levels of the endogenous NF-kappaB inhibitor IkappaBalpha in arteries at 150 mm Hg (52+/-7%; P<0.001), as detected by Western blot. To study the functional role of the pressure-induced activation of NF-kappaB, we evaluated the rate of apoptosis (TUNEL method) in carotid arteries cultured with or without an inhibitor peptide blocking nuclear translocation of NF-kappaB. No apoptosis was detected in control arteries either at 80 or 150 mm Hg. However, in the presence of the NF-kappaB inhibitor peptide, we observed apoptosis in vessels at 80 mm Hg (5+/-1%; P<0.001 versus untreated controls), which was markedly increased in vessels at 150 mm Hg (14+/-2%; P<0.001). These results were corroborated by immunohistochemical analysis showing positive staining for cleaved caspase 3 in vessels at 80 mm Hg treated with the NF-kappaB inhibitor peptide, which was additionally enhanced in treated vessels at 150 mm Hg. Our findings demonstrate that high intraluminal pressure activates NF-kappaB in arteries. Moreover, the activation of NF-kappaB seems to play a key role in preventing apoptosis in vascular cells, especially when vessels are exposed to high intraluminal pressure.

Animals↗
PubMed2003

[Acute coronary thrombosis].

Atherosclerosis is an inflammatory disease of the arterial wall. Ischaemic manifestations of atherosclerosis are mainly due to thrombus formation upon a superficially eroded (denudation of luminal endothelium, 40% of cases) or deeply ruptured (fibrous cap rupture, 60% of cases) plaques. Recent studies have unraveled potentially critical roles for both inflammatory and apoptotic processes in plaque unstability leading to thrombus formation. Pro-inflammatory mediators have been particularly implicated in the loss of smooth muscle cells and the promotion of collagen degradation that are responsible for fibrous cap rupture, whereas apoptosis has been identified as one of the major determinants of plaque thrombogenicity.

Acute Disease↗
PubMed2003

Decreased atherosclerotic lesion formation in CX3CR1/apolipoprotein E double knockout mice.

BACKGROUND: Fractalkine (CX3CL1), a CX3C chemokine, is expressed in the vessel wall and mediates the firm adhesion and chemotaxis of leukocytes expressing its receptor, CX3CR1. A polymorphism in the CX3CR1 gene is associated with low CX3CR1 expression and reduced risk of acute coronary disease in humans. METHODS AND RESULTS: We generated CX3CR1-deficient mice (CX3CR1(-/-)) by targeted gene disruption and crossed them with the proatherogenic apolipoprotein E-deficient mice (apoE(-/-)). Here we show that the extent of lipid-stained lesions in the thoracic aorta was reduced by 59% in CX3CR1/apoE double knockout mice compared with their CX3CR1(+/+)/apoE(-/-) littermates. The development of atherosclerosis in the aortic sinus was also markedly altered in the double knockout mice, with 50% reduction in macrophage accumulation. Although lesions of CX3CR1(-/-) mice were smaller in size, they retained a substantial accumulation of smooth muscle cells and collagen, features consistent with a stable plaque phenotype. Finally, CX3CR1(+/-)/apoE(-/-) mice showed the same reduction in atherosclerosis as the CX3CR1(-/-)/apoE(-/-) mice. CONCLUSIONS: The CX3CR1-CX3CL1 pathway seems to play a direct and critical role in monocyte recruitment and atherosclerotic lesion development in a mouse model of human atherosclerosis.

Alleles↗