Dysfonction endothéliale et polyarthrite rhumatoïde : cinétique, mécanismes et traitements. Etude chez le rat

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease which is associated with excessive cardiovascular (CV) mortality and morbidity. Endothelial dysfunction (ED) has been identified as a key element in the development of atherosclerosis and CV complications in RA. However, both pathophysiology and therapeutic options of ED are still ill-defined. In this work we aimed to determine the time-course of ED in RA, the differences of ED between macro- and microvasculature, the link between ED and circulating markers of inflammation or endothelial activation, and the effect of an anti-TNFα agent, Etanercept, for reversing ED. Experiments have been conducted on the model of adjuvant-induced arthritis (AIA) in Lewis rats. Endothelial function was assessed in isolated aortic rings (macrovasculature) and in isolated mesenteric arteries (microvasculature). In a first study, we showed that ED occurred earlier in microvascular bed (first symptoms of arthritis) than in macrovascular bed (at maximal inflammation), and is more sustainable. Circulating levels of CRP, ICAM-1 and VCAM-1 cannot be used as markers of ED in arthritis.In a second study, we characterized the mechanisms involved in ED in AIA rats. Our results showed that despite the absence of aortic ED in the early stage of arthritis (first symptoms of arthritis), endothelial abnormalities are already present but initially compensated by an increase in NOS activity. We identified plasma levels of IL-1β, TNF-α and MIP-1α as potential circulating markers of macrovascular ED in RA.Our third study demonstrated the ability of a curative treatment with Etanercept, an anti-TNFα, to improve endothelial function in the AIA model, regardless its impact on traditional CV risk factors and on the severity of the diseaseIn conclusion, our results led to improve the understanding of ED in case of arthritis. They provide diagnostic and therapeutic perspectives to enhance the management of CV risk in RA patientsLa polyarthrite rhumatoïde (PR) représente le plus fréquent des rhumatismes inflammatoires chroniques. En plus d’une atteinte ostéo-articulaire responsable de l’invalidité fonctionnelle, la PR est associée à une surmortalité d’origine cardiovasculaire (CV). Les données récentes de la littérature identifient la dysfonction endothéliale (DE) comme la pierre angulaire du processus athéromateux et des complications CV au cours de la PR. Cependant, la physiopathologie et les possibilités thérapeutiques de cette DE sont mal connues. L’objectif de mon travail a été d’étudier la cinétique de la DE au cours de la PR, la différence de sa survenue entre les lits macrovasculaire et microvasculaire, le lien entre la DE et des marqueurs circulants d’inflammation ou d’activation endothéliale, et l’impact de l’Etanercept, un anti-TNFα utilisé comme traitement de fond de la PR, sur la DE. Les expériences ont été réalisées sur le modèle d’Arthrite Induite à l’Adjuvant (AIA) chez le rat Lewis, la fonction endothéliale étant étudiée sur des anneaux aortiques isolés (macrocirculation) ou des artères mésentériques isolées (microcirculation).Dans la première étude, nous avons montré que la DE microvasculaire est d’apparition plus précoce que la DE macrovasculaire (premiers symptômes d’arthrite versus inflammation maximale), et plus durable. Les taux circulants de CRP, ICAM-1 et VCAM-1 ne peuvent pas être utilisés comme marqueurs de DE dans l’arthrite.Dans la deuxième étude, nos résultats ont montré que, malgré l’absence de DE aortique au stade précoce de l’arthrite (premiers symptômes d’arthrite), les anomalies endothéliales sont déjà présentes mais initialement compensées par une augmentation de l’activité de la NOS. Nous avons identifié l’IL-1β, le TNF-α et le MIP-1α plasmatiques comme des marqueurs circulants potentiels de la DE macrovasculaire dans la PR.Notre troisième étude a démontré la capacité d’un traitement curatif par Etanercept : un anti TNF-α, à améliorer la fonction endothéliale dans le modèle AIA, indépendamment de son impact sur les facteurs traditionnels de risque CV et sur la sévérité de la maladie.En conclusion, nos travaux ont permis de mieux comprendre la DE en cas d’arthrite, et ont apporté des éléments qui ouvrent des perspectives diagnostiques et thérapeutiques pour une meilleure prise en charge du risque CV du patient P

Endothelial dysfunction and rheumatoïd arthritis : time-course, mechanisms and treatment. Study in adjuvant-induced arthritis rat model

La polyarthrite rhumatoïde (PR) représente le plus fréquent des rhumatismes inflammatoires chroniques. En plus d’une atteinte ostéo-articulaire responsable de l’invalidité fonctionnelle, la PR est associée à une surmortalité d’origine cardiovasculaire (CV). Les données récentes de la littérature identifient la dysfonction endothéliale (DE) comme la pierre angulaire du processus athéromateux et des complications CV au cours de la PR. Cependant, la physiopathologie et les possibilités thérapeutiques de cette DE sont mal connues. L’objectif de mon travail a été d’étudier la cinétique de la DE au cours de la PR, la différence de sa survenue entre les lits macrovasculaire et microvasculaire, le lien entre la DE et des marqueurs circulants d’inflammation ou d’activation endothéliale, et l’impact de l’Etanercept, un anti-TNFα utilisé comme traitement de fond de la PR, sur la DE. Les expériences ont été réalisées sur le modèle d’Arthrite Induite à l’Adjuvant (AIA) chez le rat Lewis, la fonction endothéliale étant étudiée sur des anneaux aortiques isolés (macrocirculation) ou des artères mésentériques isolées (microcirculation).Dans la première étude, nous avons montré que la DE microvasculaire est d’apparition plus précoce que la DE macrovasculaire (premiers symptômes d’arthrite versus inflammation maximale), et plus durable. Les taux circulants de CRP, ICAM-1 et VCAM-1 ne peuvent pas être utilisés comme marqueurs de DE dans l’arthrite.Dans la deuxième étude, nos résultats ont montré que, malgré l’absence de DE aortique au stade précoce de l’arthrite (premiers symptômes d’arthrite), les anomalies endothéliales sont déjà présentes mais initialement compensées par une augmentation de l’activité de la NOS. Nous avons identifié l’IL-1β, le TNF-α et le MIP-1α plasmatiques comme des marqueurs circulants potentiels de la DE macrovasculaire dans la PR.Notre troisième étude a démontré la capacité d’un traitement curatif par Etanercept : un anti TNF-α, à améliorer la fonction endothéliale dans le modèle AIA, indépendamment de son impact sur les facteurs traditionnels de risque CV et sur la sévérité de la maladie.En conclusion, nos travaux ont permis de mieux comprendre la DE en cas d’arthrite, et ont apporté des éléments qui ouvrent des perspectives diagnostiques et thérapeutiques pour une meilleure prise en charge du risque CV du patient PRRheumatoid arthritis (RA) is the most common systemic autoimmune disease which is associated with excessive cardiovascular (CV) mortality and morbidity. Endothelial dysfunction (ED) has been identified as a key element in the development of atherosclerosis and CV complications in RA. However, both pathophysiology and therapeutic options of ED are still ill-defined. In this work we aimed to determine the time-course of ED in RA, the differences of ED between macro- and microvasculature, the link between ED and circulating markers of inflammation or endothelial activation, and the effect of an anti-TNFα agent, Etanercept, for reversing ED. Experiments have been conducted on the model of adjuvant-induced arthritis (AIA) in Lewis rats. Endothelial function was assessed in isolated aortic rings (macrovasculature) and in isolated mesenteric arteries (microvasculature). In a first study, we showed that ED occurred earlier in microvascular bed (first symptoms of arthritis) than in macrovascular bed (at maximal inflammation), and is more sustainable. Circulating levels of CRP, ICAM-1 and VCAM-1 cannot be used as markers of ED in arthritis.In a second study, we characterized the mechanisms involved in ED in AIA rats. Our results showed that despite the absence of aortic ED in the early stage of arthritis (first symptoms of arthritis), endothelial abnormalities are already present but initially compensated by an increase in NOS activity. We identified plasma levels of IL-1β, TNF-α and MIP-1α as potential circulating markers of macrovascular ED in RA.Our third study demonstrated the ability of a curative treatment with Etanercept, an anti-TNFα, to improve endothelial function in the AIA model, regardless its impact on traditional CV risk factors and on the severity of the diseaseIn conclusion, our results led to improve the understanding of ED in case of arthritis. They provide diagnostic and therapeutic perspectives to enhance the management of CV risk in RA patient

Vasorelaxing effect of a TrkB receptor agonist on mesenteric arteries

International audienceIntroduction: Brain-derived neurotrophic factor (BDNF) is a neurotrophin unanimously recognized for its promoting effect on neuroplasticity and cognition, through activation of tropomyosin receptor kinase B (TrkB). In opposition with the traditional thinking that neurons are the main source of BDNF, endothelial cells were found to express large amounts of BDNF. Exogenous BDNF was reported to exert vasodilating properties on isolated pulmonary artery and aorta. However, whether peripheral vascular resistances are controlled by endothelial BDNF is not known. To address this question, we investigated the vasorelaxant properties and the underlying signaling pathways of a TrkB agonist (LM22A4) on mesenteric arteries in rat.Material and methods: Experiments were conducted on third-order mesenteric arteries harvested from 24 male Wistar rats (6–8 week-old) and mounted in isometric conditions. Intact or endothelium-denuded arteries were pre-constricted with phenylephrine (3 × 10−5 m) and relaxed with cumulative concentrations LM22A4 (10−11–10−4 m). Cyclotraxin B (10−6 m) was used as a TrkB antagonist. Vessels were also incubated with various specific inhibitors to assess the signaling pathways activated by LM22A4 including nitric oxide- (L-NAME, 10−4 m), endothelium-derived hyperpolarizing factor- (EDHF, apamin 10−7 m and charybdotoxin 10−7 m), PGI2- (U51605, 10−6 m), PI3K/Akt- (wortmannin 3 × 10−8 m), CaM/CaMKII (Calmidazolium 10−5 m, KN-62 10−5 m) and PLCγ- (U73122 10−5 m) dependent pathways.Results: Our results showed that LM22A4 induced vasorelaxation in mesenteric arteries, with maximal effect Emax 51 ± 7% and concentration for 50% of maximal effect (EC50) of approximately 0.025 μm. Endothelium removal as well as cyclotraxin B significantly blunted the effect of LM22A4. In addition, endothelium-dependent relaxant effect of LM22A4 was reduced by inhibitors of NO, EDHF, PGI2 production and PI3K/Akt signaling pathways. By contrast, vasodilating effect of LM22A4 was not modified by inhibition of CaM/CaMKII and PLCγ pathways.Discussion/Conclusion: In conclusion, our data demonstrated for the first time the capacity of a TrkB agonist to vasodilate peripheral resistance arteries. This effect involved activation of endothelial TrkB receptors and relied on production of NO, EDHF, PGI2 and activation of PI3K/Akt pathway. These data, combined with evidence that endothelial BDNF expression is decreased by hypertension and increased by physical training, suggest a possible role of BDNF in endothelial dysfunction

Vasorelaxing effect of a TrkB receptor agonist on mesenteric arteries

International audienceIntroduction: Brain-derived neurotrophic factor (BDNF) is a neurotrophin unanimously recognized for its promoting effect on neuroplasticity and cognition, through activation of tropomyosin receptor kinase B (TrkB). In opposition with the traditional thinking that neurons are the main source of BDNF, endothelial cells were found to express large amounts of BDNF. Exogenous BDNF was reported to exert vasodilating properties on isolated pulmonary artery and aorta. However, whether peripheral vascular resistances are controlled by endothelial BDNF is not known. To address this question, we investigated the vasorelaxant properties and the underlying signaling pathways of a TrkB agonist (LM22A4) on mesenteric arteries in rat.Material and methods: Experiments were conducted on third-order mesenteric arteries harvested from 24 male Wistar rats (6–8 week-old) and mounted in isometric conditions. Intact or endothelium-denuded arteries were pre-constricted with phenylephrine (3 × 10−5 m) and relaxed with cumulative concentrations LM22A4 (10−11–10−4 m). Cyclotraxin B (10−6 m) was used as a TrkB antagonist. Vessels were also incubated with various specific inhibitors to assess the signaling pathways activated by LM22A4 including nitric oxide- (L-NAME, 10−4 m), endothelium-derived hyperpolarizing factor- (EDHF, apamin 10−7 m and charybdotoxin 10−7 m), PGI2- (U51605, 10−6 m), PI3K/Akt- (wortmannin 3 × 10−8 m), CaM/CaMKII (Calmidazolium 10−5 m, KN-62 10−5 m) and PLCγ- (U73122 10−5 m) dependent pathways.Results: Our results showed that LM22A4 induced vasorelaxation in mesenteric arteries, with maximal effect Emax 51 ± 7% and concentration for 50% of maximal effect (EC50) of approximately 0.025 μm. Endothelium removal as well as cyclotraxin B significantly blunted the effect of LM22A4. In addition, endothelium-dependent relaxant effect of LM22A4 was reduced by inhibitors of NO, EDHF, PGI2 production and PI3K/Akt signaling pathways. By contrast, vasodilating effect of LM22A4 was not modified by inhibition of CaM/CaMKII and PLCγ pathways.Discussion/Conclusion: In conclusion, our data demonstrated for the first time the capacity of a TrkB agonist to vasodilate peripheral resistance arteries. This effect involved activation of endothelial TrkB receptors and relied on production of NO, EDHF, PGI2 and activation of PI3K/Akt pathway. These data, combined with evidence that endothelial BDNF expression is decreased by hypertension and increased by physical training, suggest a possible role of BDNF in endothelial dysfunction

Association between endothelial dysfunction and brain BDNF levels in a rat model of arthritis

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Activation of endothelial TrkB receptors induces relaxation of resistance arteries

International audienceWhile brain-derived neurotrophic factor (BDNF) was previously reported to induce relaxation of conduit artery, whether the BDNF/TrkB (tropomyosin-related kinase) pathway is involved in the tone control of resistance arteries is not known. This study investigated TrkB receptors levels/localization and the vasomotor effect of the TrkB receptor agonist LM22A-4 in isolated third-order mesenteric arteries from rats.Immunostaining revealed the presence of both full-length and truncated TrkB receptors, especially at the endothelial level. By using wire myography, LM22A-4 induced vascular relaxation that was significantly decreased by cyclotraxin B as a non-competitive TrkB antagonist and fully prevented by endothelium removal. Inhibitors of NO, EDHF, PGI2 production and the PI3K/Akt pathways separately reduced LM22A-4 inducedrelaxation. By contrast, inhibition of Raf/MEK, PLC gamma and CaM/CaMKII pathways did not change the relaxant effect of LM22A-4. Interestingly, BDNF also induced an endothelium and TrkB-dependent relaxation.These results indicate that endothelial TrkB activation results in the relaxation of resistance vessels via PI3K/ Akt-induced eNOS phosphorylation and production of EDHF and PGI(2). These data are consistent with the contribution of the endothelial BDNF/TrkB pathway to the regulation of peripheral vascular tone. They also validate the use of LM22A-4 as a reliable pharmacological agent for studying the vascular effect of BDNF

Vascular Arginase Is a Relevant Target to Improve Cerebrovascular Endothelial Dysfunction in Rheumatoid Arthritis: Evidence from the Model of Adjuvant-Induced Arthritis

International audiencemerging data revealed that rheumatoid arthritis (RA) is associated with higher risk of cerebrovascular diseases. Whereas cerebral endothelial dysfunction is acknowledged as a critical aspect of cerebrovascular diseases, its presence in RA and the mechanisms involved are currently unknown. By using the model of rat adjuvant-induced arthritis (AIA), the present study investigated cerebrovascular reactivity in pressurized middle cerebral arteries (MCA) on day 33 post-immunization. The results revealed that arthritis induced a dramatic decrease in the vasodilatory response to acetylcholine (ACh), ADP, and bradykinin (n = 7-9 arteries, p < 0.0001). By using nor-NOHA, L-NAME, BH4, and Tempol, the results showed that the reduced response to ACh relied on arginase overactivation (n = 8), low NOS activity (n = 8), BH4 deficiency (n = 9), and excessive superoxide production (n = 9). Immunohistological analysis revealed an endothelial upregulation of arginase 2 (p < 0.05, n = 5-6) and NADPH oxidase (p < 0.05, n = 5-7) while eNOS expression was unchanged in AIA (n = 6). To assess whether arginase inhibition may be a relevant therapeutic, AIA rats were treated with an arginase inhibitor (nor-NOHA, 40 mg/kg/day, i.p., n = 20 rats) daily from day 10 to day 33 post-immunization. The treatment alleviated the impaired response of MCA to endothelium-dependent agonists, through an increase in NOS signaling and a suppression of BH4 deficiency and superoxide overproduction. By contrast, it did not change the course of arthritis. In conclusion, arthritis induced a cerebrovascular endothelial dysfunction involving an imbalance in the arginase/NOS pathway. Arginase inhibition appears as a promising therapy beyond anti-rheumatic drugs for reducing the risk of cerebrovascular diseases in RA

Endothelial Dysfunction in Rheumatoid Arthritis: Mechanistic Insights and Correlation with Circulating Markers of Systemic Inflammation

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Microvascular endothelial dysfunction in rheumatoid arthritis

International audienceThe systemic autoimmune disease rheumatoid arthritis (RA) is characterized by increased cardiovascular mortality and morbidity and is an independent cardiovascular risk factor. Cardiovascular diseases (CVDs) result from accelerated atherogenesis, which is a consequence of endothelial dysfunction in the early stages of the disease. Endothelial dysfunction is a functional and reversible alteration of endothelial cells and leads to a shift in the properties of the endothelium towards reduced vasodilation, a pro-inflammatory state, and proliferative and prothrombotic properties. In RA, endothelial dysfunction can occur in the large vessels (such as the conduit arteries) and in the small vessels of the microvasculature, which supply oxygen and nutrients to the tissue and control inflammation, repair and fluid exchange with the surrounding tissues. Growing evidence suggests that microvascular endothelial dysfunction contributes to CVD development, as it precedes and predicts the development of conduit artery atherosclerosis and associated risk factors. As such, numerous studies have investigated microvascular endothelial dysfunction in RA, including its link with disease activity, disease duration and inflammation, the effect of treatments on endothelial function, and possible circulating biomarkers of microvascular endothelial dysfunction. Such findings could have important implications in the cardiovascular risk management of patients with RA