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François Mach

Publications and source records attributed to François Mach.

35 records · Page 2Linked to original sources
PubMed2004

Statins as immunomodulatory agents.

Statins have long been thought to exert their benefits by reducing cholesterol synthesis. However, the fact that mevalonate is the precursor of isoprenoids that regulate diverse cellular functions has led investigators to examine pleiotropic effects for these agents. Major histocompatibility complex class II (MHC-II) molecules, which affect the immune response and organ rejection after transplantation, may be induced by the proinflammatory cytokine interferon gamma (IFN-gamma). An experiment was conducted to determine whether statins affect the regulation of MHC-II expression by IFN-gamma in cultured human endothelial cells and monocyte/macrophages. Statins were found to repress the induction of MHC-II by IFN-gamma. This may explain the immunosuppressive effects of statins seen in two clinical trials of organ transplantation and suggest a potential role for statins as immunosuppressive agents.

Atorvastatin↗
PubMed2004

Inflammation and atherosclerosis.

It is now generally recognized that atherosclerosis is a chronic inflammatory disease, characterized by overrecruitment of leukocytes (monocytes and T-cells) to the site of inflammation. Vascular injury in response to cardiovascular risk factors promotes endothelial dysfunction, resulting in enhanced adhesion molecule expression and secretion of pro-inflammatory cytokines and chemokines. This, in turn, leads to adherence, migration and accumulation of leukocytes within atherosclerotic lesions. The recent findings on inflammatory processes involved in atherosclerosis development provide important links between risk factors and the mechanisms of atherogenesis. Thus, research interest has increasingly focused on inflammatory biomarkers as means of predicting the risk of future clinical events. Indeed, elevated plasma levels of molecules such as soluble intercellular adhesion molecule-1, interleukin-6 or C-reactive protein (CRP) have been shown to represent inflammatory markers of future cardiovascular risk. Among these, CRP has emerged as the most powerful and accessible for clinical use. A major challenge for future research is to implement these new insights in order to improve strategies for prediction, prevention and treatment of cardiovascular events.

Animals↗
PubMed2004

Role of Toll-like receptor 4 on pancreatic and pulmonary injury in a mice model of acute pancreatitis associated with endotoxemia.

OBJECTIVE: Infection of pancreatic necrosis is a severe complication of acute pancreatitis. Because Toll-like receptor 4 (TLR4) has been identified as a receptor necessary to transduct the signal of bacteria-derived lipopolysaccharide into cells, we investigated the role of TLR4 on pancreatic and pulmonary injury in acute pancreatitis and acute pancreatitis associated with endotoxemia in wild-type and TLR4-deficient mice. DESIGN: Laboratory investigation. SETTING: University laboratory. SUBJECTS: Heterozygous TLR4 mice. INTERVENTIONS: Mice were injected intraperitoneally with a supramaximal dose of cerulein each hour for 10 hrs. To mimic infection, additional groups of mice were injected with lipopolysaccharide in the presence or absence of cerulein injections. MEASUREMENTS AND MAIN RESULTS: The severity of acute pancreatitis was assessed by serum amylase activity, pancreatic edema, acinar cell necrosis, and pancreas myeloperoxidase activity. Lung injury was quantitated by lung microvascular permeability and lung myeloperoxidase activity. Injections of cerulein induced an edematous pancreatitis that was of similar severity in wild-type and TLR4-deficient mice. Lipopolysaccharide alone had no toxic effect on pancreas and lungs and did not worsen the pancreatic injury induced by cerulein in wild-type and TRL4-deficient mice. In contrast, lipopolysaccharide worsened pancreatitis-associated lung injury, and the deficiency in TLR4 fully prevented this aggravation. CONCLUSIONS: TLR4 may not play a role in the pancreatitis-associated lung injury but participates in the pulmonary injury mediated by endotoxemia.

Acute Disease↗
PubMed2003

Antagonism of RANTES receptors reduces atherosclerotic plaque formation in mice.

Increasing evidence supports the involvement of inflammation in the early phases of atherogenesis. Recruitment of leukocytes within the vascular wall, controlled by chemokines, is an essential process in the development of this common disease. In this study, we report that blocking a chemokine pathway in vivo with the CC chemokine antagonist Met-RANTES reduces the progression of atherosclerosis in a hypercholesterolemic mouse model. The reduction of lesions was correlated with a diminution of expression of several major chemokines and chemokine receptors, a decrease in leukocyte infiltration, and an increase of collagen-rich atheroma, features associated with stable atheroma. Treatment was well tolerated and serum lipid profiles were not affected. Whereas genetically engineered mice with deletion of either a CC chemokine or its receptor have demonstrated resistance to disease, to our knowledge, this is the first demonstration that treatment with a chemokine receptor antagonist limits the progression of atherosclerosis in vivo. Thus, our findings indicate that blockade of chemokine receptor/ligand interactions might become a novel therapeutic strategy to reduce the evolution of this common disease.

Animals↗
PubMed2003

Statins (HMG-CoA reductase inhibitors) reduce CD40 expression in human vascular cells.

OBJECTIVE: HMG-CoA reductase inhibitors (statins) possess anti-inflammatory and immunomodulatory properties that are independent of their lipid-lowering action. As the CD40-CD40L signaling pathway is implicated in the modulation of inflammatory responses between vascular cells, involving adhesion molecules, pro-inflammatory cytokines, chemokines, we sought to investigate the potential role of statins in regulating the expression of CD40. METHODS AND RESULTS: Using Western blot, flow cytometry and immunohistochemistry analyses, we observed that four different statins reduced IFN-gamma-induced CD40 expression in human vascular cells (endothelial cells, smooth muscle cells, macrophages and fibroblasts). This effect was dose-dependent (from 5 microM to 80 nM) and reversed by addition of L-mevalonate. Activation of vascular cells by human recombinant CD40L, as measured by ELISA for IL-6, IL-8 and MCP-1, was strongly reduced when cells were treated with statins. Immunostaining of human carotid atherosclerotic lesions of patients subjected to statin treatment revealed less CD40 expression on a 'per vascular cell' basis compared to control patients. Although many pleiotropic effects of statins are mediated by nitric oxide synthase (NOS)- or peroxisome proliferator-activated receptor (PPAR)-dependent signaling pathways, we observed similar statin-induced reduction of CD40 expression using NOS inhibitors or different PPAR ligands. CONCLUSION: Statins decrease CD40 expression and CD40-related activation of vascular cells. These effects are partially reversed by the HMG-CoA reductase product L-mevalonate and are mediated by NOS- or PPAR-dependent pathways. Altogether, these findings provide mechanistic insight into the beneficial effects of statins on atherogenesis. They also provide a scientific rationale for the use of statins as immunomodulators after organ transplantation.

Animals↗
PubMed2003

Reduced connexin43 expression inhibits atherosclerotic lesion formation in low-density lipoprotein receptor-deficient mice.

BACKGROUND: Gap junctions allow the direct exchange of ions and small molecules between cells in contact, thus coordinating physiological processes such as cell growth and differentiation. We have recently demonstrated increased expression of the gap junction protein connexin43 (Cx43) in specific subsets of cells in atherosclerotic lesions. Because the development of atherosclerosis depends critically on paracrine cell-to-cell interactions, we hypothesized that direct intercellular communication via gap junctions may be another factor controlling atherogenesis. METHODS AND RESULTS: The role of Cx43 in atherogenesis was examined by use of both a genetic and a pharmacological approach. First, atherosclerosis-susceptible LDL receptor-deficient (LDLR-/-) mice with normal (Cx43+/+) or reduced (Cx43+/-) levels of Cx43 were fed a cholesterol-rich diet for 14 weeks. The progression of atherosclerosis was reduced by 50% (P<0.01) in the thoracoabdominal aorta and in the aortic roots of Cx43+/-LDLR-/- mice compared with Cx43+/+LDLR-/- controls. Atheroma in Cx43+/-LDLR-/- mice contained fewer inflammatory cells and exhibited thicker fibrous caps with more collagen and smooth muscle cells. Next, we observed that HMG-CoA reductase inhibitors, or "statins," lipid-lowering drugs well known for their pleiotropic antiatherogenic effects, reduced Cx43 expression in primary human vascular cells in vitro. Atheroma of LDLR-/- mice treated orally with pravastatin contained fewer inflammatory cells and exhibited thicker fibrous caps than controls. This was associated with reduced Cx43 expression in lesions of statin-treated mice. CONCLUSIONS: These data indicate a critical role for Cx43-mediated gap junctional communication in atherosclerotic plaque formation.

Animals↗
PubMed2003

Atherosclerosis: anti-inflammatory and immunomodulatory activities of statins.

Large clinical trials have demonstrated that HMG-CoA reductase inhibitors or 'statins' greatly reduce cardiovascular-related morbidity and mortality. The beneficial effects of statins were first assumed to result from their ability to reduce cholesterol synthesis and improve serum lipid profiles. In recent years, however, numerous pleiotropic effects of statins on atherosclerotic lesions have been described. In this review, we summarize the actions of statins on different aspects of atherosclerotic plaque development. These include endothelial dysfunction, leukocyte recruitment and inflammation, smooth muscle cell activation/proliferation, and finally plaque rupture and thrombosis.

Animals↗
PubMed2003

Statins as novel immunomodulators: from cell to potential clinical benefit.

In the last decades, substantial progress has been made in understanding the relationship between lipid disorders and prevention of cardiac ischemic disease. Statins competitively inhibit 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase, an enzyme crucial to cholesterol biosynthesis. Statins have long been thought to exert their benefits by reducing cholesterol synthesis, but the fact that mevalonate is the precursor of isoprenoids that regulate diverse cellular functions has led investigators to examine pleiotropic effects for these agents. Statins have never been shown to be involved in the immune response, although two clinical trials have suggested that in heart transplant patients, statin therapy has beneficial effects on the incidence of cardiac rejection, coronary vasculopathy, and survival. Major Histocompatibility Complex class II (MHC-II) molecules, which affect the immune response and organ rejection after transplantation, may be induced by the pro-inflammatory cytokine interferon gamma (IFN-gamma). Recently, it has been demonstrated that statins repress the induction of MHC-II by IFN-gamma in vitro, and thus may suggest a potential role for statins as immunosuppressive agents in vivo. Indeed, two recent in vivo studies performed on different animal models provide further evidence that statin-treatment positively influence immunological disorders.

Adjuvants, Immunologic↗
PubMed2002

PPARgamma but not PPARalpha ligands are potent repressors of major histocompatibility complex class II induction in atheroma-associated cells.

Peroxisome proliferator-activated receptors (PPARs) are essential in glucose and lipid metabolism and are implicated in metabolic disorders predisposing to atherosclerosis, such as diabetes and dyslipidemia. Conversely, antidiabetic glitazones and hypolipidemic fibrate drugs, known as PPARgamma and PPARalpha ligands, respectively, reduce the process of atherosclerotic lesion formation, which involves chronic immunoinflammatory processes. Major histocompatibility complex class II (MHC-II) molecules, expressed on the surface of specialized cells, are directly involved in the activation of T lymphocytes and in the control of the immune response. Interestingly, expression of MHC-II has recently been observed in atherosclerotic plaques, and it can be induced by the proinflammatory cytokine interferon-gamma (IFN-gamma) in vascular cells. To explore a possible role for PPAR ligands in the regulation of the immune response, we investigated whether PPAR activation affects MHC-II expression in atheroma-associated cells. In the present study, we demonstrate that PPARgamma but not PPARalpha ligands act as inhibitors of IFN-gamma-induced MHC-II expression and thus as repressors of MHC-II-mediated T-cell activation. All different types of PPARgamma ligands tested inhibit MHC-II. This effect of PPARgamma ligands is due to a specific inhibition of promoter IV of CIITA and does not concern constitutive expression of MHC-II. Thus, the beneficial effects of antidiabetic PPARgamma activators on atherosclerotic plaque development may be partly explained by their repression of MHC-II expression and subsequent inhibition of T-lymphocyte activation.

Arteriosclerosis↗
PubMed2002

Altered pattern of vascular connexin expression in atherosclerotic plaques.

Paracrine cell-to-cell interactions are crucial events during atherogenesis. However, little is known about the role of direct intercellular communication via gap junctions during this process. We have investigated the expression pattern of 3 vascular gap junction proteins (connexins) in mouse and human atherosclerotic plaques. Low density lipoprotein receptor-deficient mice were fed a high-fat diet for 0, 6, 10, or 14 weeks to induce different stages of atherosclerosis. Connexin37 (Cx37) and Cx40 were detected in the endothelium, and Cx43 was detected in the media of nondiseased aortas. In early atheromas, endothelial and medial connexin expression remained unchanged, and "islets" of Cx43 in smooth muscle cells and Cx37 in macrophages were observed in the neointima. In advanced atheromas, Cx37 was detected in medial smooth muscle cells and in macrophages in the lipid core but not in the endothelium covering the plaques. Cx40 could also no longer be detected in the endothelium covering the plaques. Cx43, on the other hand, was detected in the endothelium covering the shoulder of the plaques and also sparsely in neointimal smooth muscle cells. Similar results were obtained for human carotid arteries. In conclusion, vascular connexins are differentially expressed by atheroma-associated cells within lesions. These observations suggest a role for gap junctional intercellular communication during atherogenesis.

Animals↗
PubMed2002

Influence of Helicobacter pylori infection during atherogenesis in vivo in mice.

Inflammatory diseases may have a role in the pathogenesis of atherosclerosis. Several epidemiological and clinical studies have explored the possible association between Helicobacter pylori seropositivity, cardiovascular risk factors, and ischemic heart disease. The contradictory results of these studies have fueled a debate regarding the link between H pylori infection and atherogenesis. This study tested the hypothesis that H pylori infection might influence atherosclerosis in vivo in mice. Male wild-type C57/Bl6 mice and LDL-receptor deficient congenic mice were randomly assigned for infection with H pylori. All animals were fed a high-cholesterol diet (1.25%) for 6 or 12 weeks. At autopsy, we compared aortic atherosclerotic lesion formation and lipid deposition. H pylori infection influenced neither the progression of atherosclerotic lesions nor lipid deposition. Moreover, the cellularity of atherosclerotic lesions (macrophages and T cells) did not differ between mice infected or not infected with H pylori. This in vivo study performed in a mouse model of atherosclerosis revealed no indication that H pylori infection might contribute to the development of atherosclerotic lesion formation. The full text of this article is available at http://www.circresaha.org.

Animals↗
PubMed2002

Statins as immunomodulators.

HMG-CoA reductase inhibitors, or statins, are effective lipid lowering agents, extensively used in medical practice. Statins have never been shown to be involved in the immune response, although few clinical reports have suggested a better outcome of cardiac transplantation in patients under pravastatin therapy. Major histocompatibility complex class II (MHC-II) molecules are directly involved in the activation of T lymphocytes and in the control of the immune response. Whereas only a limited number of specialized cell types express MHC-II constitutively, numerous other cells become MHC-II positive upon induction by interferon gamma (IFN-gamma). We and others recently demonstrated that statins act as direct inhibitors of induction of MHC-II expression by IFN-gamma and thus as repressors of MHC-II-mediated T cell activation. This effect was observed in several cell types, including primary human endothelial cells and macrophages. Interestingly, this inhibition is specific for inducible MHC-II expression and does not concern either constitutive expression of MHC-II or expression of MHC-I. In repressing induction of MHC-II, and subsequent T lymphocyte activation, statins therefore behave as a novel type of immunomodulator. This unexpected effect provides a scientific rationale for suggesting the use of statins as novel immunosuppressors, not only in organ transplantation but in numerous other pathologies as well.

Animals↗
PubMed2002

Immunosuppressive effects of statins.

3-Hydroxy-3-methhylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, are effective lipid lowering agents, extensively used in medical practice [Circulation 2000;101:207; J Am Med Assoc 2000;283:2935]. Statins have never been shown to be involved in the immune response, although reports have suggested a better outcome of cardiac transplantation in patients under pravastatin therapy [New Engl J Med 1995;333:621; Circulation 1997;96:1398]. Major histocompatibility complex class II (MHC class II) molecules are directly involved in the activation of T lymphocytes and in the control of the immune response. Whereas only a limited number of specialized cell types express MHC-II constitutively, numerous other cells become MHC-II positive upon induction by interferon-gamma (IFN-gamma) [Annu Rev Immunol 1996;14:301]. This complex regulation is under the control of the transactivator CIITA [Science 1994;265:106]. Recently, we demonstrated that statins act as direct inhibitors of induction of MHC-II expression by IFN-gamma and thus as repressors of MHC-II-mediated T cell activation [Nat Med 2000;6:1399; Swiss Med Wkly 2001;131:41]. This effect of statins is due to inhibition of the inducible promoter IV of the transactivator CIITA. Interestingly, this inhibition is specific for inducible MHC-II expression and does not concern constitutive expression of CIITA and MHC-II. In repressing induction of MHC-II, and subsequent T lymphocyte activation, statins therefore behave as a novel type of immunomodulator. This unexpected effect provides a scientific rationale for suggesting the use of statins as novel immunosuppressors, not only in organ transplantation but in numerous other pathologies as well.

Adjuvants, Immunologic↗
PubMed2002

Toward a role for statins in immunomodulation.

The family of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) inhibitors, collectively known as statins, is used clinically to reduce cholesterol levels in patients. Recent reports suggest that not only would statin therapy be beneficial for at-risk (genetically predisposed) people without symptoms of hypercholesterolemia, but that statins may have beneficial, pleiotropic effects in the treatment of autoimmune diseases. Youssef et al. have described how an HMG-CoA inhibitor, atorvastatin, might ameliorate experimental autoimmune encephalomyelitis (EAE), the mouse model for human multiple sclerosis. The possible clinical use of statins as anti-inflammatory drugs has also been demonstrated in other published reports. These provocative results suggest a role for statins in relieving autoimmune diseases such as multiple sclerosis.

Adjuvants, Immunologic↗
PubMedDate not supplied

Dual benefit of reduced Cx43 on atherosclerosis in LDL receptor-deficient mice.

Paracrine cell-to-cell interactions are crucial events during atherogenesis, however, little is known on the role of gap junctional communication during this process. We recently demonstrated increased expression of Cx43 in intimal smooth muscle cells and in a subset of endothelial cells covering the shoulder of atherosclerotic plaques. The purpose of this study was to examine the role of Cx43 in the development of atherosclerosis in vivo. Atherosclerosis-susceptible LDL receptor-deficient (LDLR(-/-)) mice were intercrossed with mice heterozygous for Cx43 (Cx43(+/-) mice). Male mice with normal (Cx43(+/+)LDLR(-/-)) or reduced (Cx43(+/-)LDLR(-/-)) Cx43 level of 10 weeks old were fed a cholesterol-rich diet (1.25%) for 14 weeks. Both groups of mice showed similar increases in serum lipids and body weight. Interestingly, the progression of atherosclerosis was reduced by 50% (P < 0.01) in the thoraco-abdominal aorta and in the aortic roots of Cx43(+/-)LDLR(-/-) mice compared with Cx43(+/+)LDLR(-/-) littermate controls. In addition, atheroma in Cx43(+/-)LDLR(-/-) mice contained fewer inflammatory cells and exhibited thicker fibrous caps with more collagen and smooth muscle cells, important features associated, in human, with stable atherosclerotic lesions. Thus, reducing Cx43 expression in mice provides beneficial effects on both the progression and composition of the atherosclerotic lesions.

Animals↗