dans les maldies vasculaires à remodelage
Cette partie de projet a fait l'objet d'une publication dans la revue American Journal of Physiology Heart and Circulatory Physiology (paru en ligne le 13 août 2010). Les travaux ont été reproduits dans la version finale publiée avec l'autorisation du journal (American Physiological Society). Ces travaux ont été effectués en étroite collaboration avec Mélanie Roy. Nos contributions à l'élaboration de cette publication ont été équivalentes. Jolyane Meloche, 3e auteure, a participé aux travaux et une des figures est le fruit de son travail.
L'assistante de recherche du Dr Richard Geneviève Robitaille, 4e auteure, a également
participé aux travaux. Dr Agharazii a participé à l'élaboration du projet et nous a permis d'avoir des données cliniques. Les Dr Bonnet et Richard ont participé activement à l'écriture et à la correction de l'article. J'ai participé à la première version du manuscript, à son amélioration et à sa correction finale.
3.1 Résumé
Les maladies vasculaires à remodelage (MVR) sont caractérisées par des cellules musculaires lisses vasculaires (CMLV) présentant une augmentation de l'inflammation, une prolifération et une résistance à l'apoptose. Ce phénotype est attribué en partie par l'activation du facteur de transcription HIF-1 «hypoxia-inducible factor-1». Il a été démontré d'une part que les cytokines peuvent agir comme activateurs de HIF-1 chez les CMLV et d'autre part qu'une augmentation des niveaux de TNF «tumor necrosis facton> est associée aux maladies vasculaires. Notre hypothèse est que l'activation de HIF-1 médiée par le TNF induit une MVR. In vitro, nous avons démontré une augmentation de la prolifération et une résistance à l'apoptose médiées par l'activation de HIF-1 via le TNF. In vivo, l'inhibition de TNF diminue le remodelage de l'artère carotide chez le rat, associé à une faible activation de HIF-1. L'utilisation d'inhibiteurs de TNF pourrait représenter un outil intéressant dans le traitement des MVR.
Am J Pkiaol Htan C u r P n r u d 2 » HOOO-HOOO. 2010 Fust pubbsbed AofoM 13. 2010: dor 10 I I51*,pfc«i 0OS62.2OI0
TRANSLATIONAL PHYSIOLOGY I
Tumor necrosis factor inhibitors as novel therapeutic tools for vascular remodeling diseases
Caroline M. Lambert,* Mflank Roy,* Jolyan* Meiodw, Genevieve A. Robitailk, Mohsm Aghanizii. Darren E. Richard, and Sébastien Bonnet
Centre de recherche du Ctmm Hospitalier Universitaire de Québec, L Hôtel-Dieu de Québec. Faculté de Médecine. L'nneniié Laval. Québec, Canada
Subnaucd 11 Jonc 2010. accepted in fiaal form 6 AnfuM 2010
Laiabert CM. Roi M. Melorhc J. RoUtaiRe CA. Agharazï M. Richard DE. Boaari S. Tumor necrosis factor inhibitors is novel therapeutic took for vascular remodeling diseases Aai J Ptnsiol Heart Cin Phyiiot 299: HOOO-HOOO. 2010. First published August 13. 2010; doi:IO.II52*ajpheart.005«.:010 — VascuL» remodeling diseases (VRDs) are characterized by enhanced inflammation and proliferative and apoptosis -resistant vascular smooth muscle cells (VSMCsi. The sustainabUity of this phénotype has been attributed in part to the activation of the transcription factor hypoxia-inducible factor-1 (HIF-1 ). There is evidence that circulating cytokines cao act as HIF-1 activators in a variety of tissues, including VSMC». In- creased circulating tumor necrosis factor (TNF) levels have been associated with vascular «diseases, but die mechanisms involved re- main unknown. We hypothesized that increased circulating levels of TNF promotes VRDs by the activation of HIF-1. resulting ia VSMC proliferation and resistance to apoptosis. Circulating TNF levels were significantly increased in patients with vascular diseases (a = 19) compared with healthy donors (a = 20). Using human carotid artery smooth muscle cells (CASMCs), wa demonstrated that TNF (100 ng/mli activates HIF-1 (HIF-la expression I. leading to increased CASMC proliferation (Ki-67 and PCNA staining) and resistance to mitochoodnal-dependent apoptosis [letramethylrhodamine methyl es- ter perchlorale (TMRM). terminal deoxyrodeotide transferase medi- aled dUTP nick end labeling (TUNEL). annexin-V staining]. In vivo. TNF inhibition using polyethylene glycol coupled with TNF mem- brane teceptor I (FEGsTNFRI). a soluble TNF receptor inhibiting circulating TNF. prevented caroud artery postinjury media remodel- ing and néointima development in rats. This effets was associated with lowered HIF-1 activation and decreased CASMC proliferation. In con- clusion, we demonstrate for the fust time that the inhibition of the TNF/Aki/HIF-1 axis prevents vascular remodeling TNF inhibitors may therefore represent new and interesting therapeutic tools against VRDs inflammation: hypoxia-inducible factor-1 : apoptosis
VASCULAR REMOCBJNO DISEASES (VRDs). such «is restenosis and atherosclerosis, aie characterized by enhanced inflammation, vascular smooth muscle cell (VSMC) proliferation, and apop- tosis resistance within the vascular wall. We previously de- scribed that the sustainability of this pbenotype required the Akt-dependent activation of the transcriptional regulator hy- poxia-inducible factor-1 (HIF-1) (23). However, the mecha- nisms leading to HIF-1 activation in VRDs remain unclear.
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Increasing evidence points to a role for cytokines in the etiology of VRDs ( 1.8.9.27.32). For example, several studies bave shown that patients with higher levels of circulating inflammatory markers, including the proinflammatory cytokine TNF. hive greater cardiovascular risks (29. 34). Moreover. TNF has been shown to induce HIF-1 activation in various cell lines (4. 11, 16. 33). Taking together, these findings suggest a potent link between circulating TNF and HIF-1 activation in VRDs.
HIF-1 is a beterodimeric transcription factor consisting of a- and p-suhunits and usually activated by low oxygen concen- trations. In normoxie conditions, the HIF-la subunit is rapidly degraded. Under hypoxia. HIF-la accumulates and allows the nuclear translocation of the heterodimer and its binding to targeted promoters ( 13). HIF-1 regulates the expression of a variety of genes involved in angiogenesis. metabolism, prolif- eration, and SUAI val (3. 17. 23. 37). Recently, we described that Akt-dependent activation of HIF-1 accounts for the met- abolic shift from glucose oxidation to complete glycolysis seen in proliferative VSMCs. Indeed, by increasing hexokinase 2 (HXK2). HIF-1 activation leads to mitochondria membrane potential hyperpolarization and resistance to apoptosis (23.28).
Several lines of evidence indicate that HIF-1 can be acti- vated by cytokines and growth factors under normoxie condi- tions (3. 3. 12. 18. 23). TNF is a cytokine for which the circulating level has been correlated to higher cardiovascular risks in patients, showing chronic low-grade inflammation because of various pathologies (31). As HIF-1. TNF is in- volved in a variety of processes including cell proliferation, survival, and apoptosis. We hypothesized that in the vascula- ture, increased levels of TNF activates HIF-1. resulting in VSMC proliferation, resistance to apoptosis. and thus vascular remodeling.
In the present work, we demonstrate that circulating TNF levels aie increased in patient» with vascular diseases. In vitro investigations, using human carotid artery smooth muscle cells thCASMC».). show that TNF activates HIF-1. resulting in CASMC proliferation and resistance to apoptosis. In vivo investigations, using the TNF inhibitor polyethylene glycol coupled with TNF membrane re«reptor 1 I PEGsTNFRl ). show the prevention of carotid artery remodeling postangioplasty by blocking the activation of HIF-1. The present study demon- strates for the first time that TNF inhibitors may represent novel and interesting therapeutic tools against VRDs.