A musculatura esquelética tem um papel fundamental para a manutenção da homeostase do organismo. A perda de massa muscular está relacionada a prejuízos na qualidade de vida de indivíduos saudáveis, além de piorar o prognóstico de pacientes com doenças sistêmicas, como o câncer, o diabetes e a insuficiência cardíaca. Em quadros mais graves de insuficiência cardíaca, a perda excessiva de massa muscular associada a um reduzido consumo de oxigênio de pico, são considerados como preditores independentes de mortalidade. O aumento do estresse oxidativo tem sido apontado como um dos principais desencadeadores do aumento da degradação de proteínas na atrofia muscular. Na presente tese, investigamos a contribuição do estresse oxidativo para a ativação das vias de sinalização NF-kB, FOXO e MAPK na atrofia muscular desencadeada pela insuficiência cardíaca. Para compreender melhor os mecanismos envolvidos na ativação dessas vias pelo estresse oxidativo, utilizamos a linhagem de células musculares C2C12. Observamos que o tratamento com peróxido de hidrogênio (1,2mM, 12h) induziu um aumento do estresse oxidativo, o qual foi capaz de aumentar a atividade do proteassoma, desencadeando a atrofia dos miotúbulos. Verificamos também um aumento da expressão proteica de alguns componentes dessas vias de sinalização, como p-p38 e NF-kB; apontando para uma ativação diferenciada dessas vias pelo estresse oxidativo. Para verificar se essas vias de sinalização relacionadas ao estresse oxidativo estavam também relacionadas à atrofia desencadeada pela insuficiência cardíaca, avaliamos um modelo experimental de ratos com insuficiência cardíaca induzida pelo infartado do miocárdio. Observamos uma redução da área de secção transversa do músculo plantar, acompanhada de um aumento da inflamação sistêmica, de p38 e das atividades de NF-kB e do proteassoma. Como o treinamento físico aeróbico tem se apresentado como uma estratégia terapêutica não farmacológica eficaz na redução do estresse oxidativo e no restabelecimento da atividade do sistema ubiquitina proteassoma, submetemos os ratos infartados ao treinamento físico aeróbico em esteira rolante. O treinamento físico aeróbico preveniu a perda de massa muscular, reduzindo a inflamação sistêmica e as atividades de NF-kB e do proteassoma. Em conjunto, os resultados apontam para o estresse oxidativo como um fator preponderante para o aumento da degradação de proteínas relacionada à atrofia muscular, seja por indução de inflamação (TNF-α) ou por sua ação direta. Além disso, observamos que as vias de sinalização são ativadas de forma diferenciada nos dois modelos, sugerindo que a degradação de proteínas nos miotúbulos está relacionada ao controle de qualidade de proteínas e, nos ratos infartados, às alterações do metabolismo, servindo como fonte de energia. Já o treinamento físico aeróbico comprovou sua eficácia no restabelecimento da atividade do proteassoma, reduzindo a inflamação e a atividade de NF-kB, prevenindo assim, a perda de massa muscular / About 40% of human body mass consists of skeletal muscles, which are involved in all aspects of movement including breathing, eating, posture, walking and reflexes. Skeletal muscle is also important as a source of heat generation and as a regulator of intermediary metabolism. Loss of skeletal muscle mass and function (skeletal muscle atrophy) leads to several functional impairments, affecting health and quality of life. It occurs in several chronic diseases such as cancer, diabetes and heart failure. In heart failure, atrophy is considered an independent predictor of poor prognosis. Oxidative stress has a crucial role in atrophy, activating different signaling pathways capable of stimulating the ubiquitin proteasome system to degrade proteins. In this study, we investigated the oxidative stress contribution to NF-kB, FOXO and MAPK signaling pathway activation in heart failure-induced atrophy. To better understand the mechanisms involved with oxidative stress and signaling pathways activation in atrophy, we have used C2C12 skeletal muscle cells. We observed that, even in high hydrogen peroxide concentrations, oxidative stress increased proteasome activity, phosphorylated p38 and NF-kB protein expression, causing myotubes atrophy. In an experimental heart failure model of infarcted rats, we evaluated plantaris muscle and verified a reduced cross sectional area, accompanied by increased systemic inflammation, p-38 protein expression and increased both NF-kB and proteasome activities. As aerobic exercise training causes a lot of beneficial effects on skeletal muscle structure and function in chronic diseases, we submitted infarcted rats to 8 weeks of aerobic exercise training on a treadmill. Aerobic exercise training prevented atrophy by reducing inflammation and both NF-kB and proteasome activities. Collectively, our data suggest a differentiated activation by oxidative stress in muscle cells and animal models. In the first case, protein degradation was involved with protein quality control; and, in the other, oxidative stress is a second messenger, stimulating protein degradation to provide substrates to metabolism. Aerobic exercise training re-established proteasome activity by reducing inflammation and NF-kB activity, preventing muscle atrophy

O treinamento físico aeróbio (TF) tem sido utilizado como um importante tratamento não farmacológico da hipertensão arterial (HA), uma vez que ele corrige a rarefação microvascular e reduz a pressão arterial; entretanto, os mecanismos envolvidos são pouco conhecidos. Investigamos se o número e a capacidade funcional das células progenitoras endoteliais (CPE) derivadas da medula óssea, sabidamente diminuídas na HA, melhoram pós TF, potencialmente contribuindo para a neovascularização e regressão da doença. O efeito do TF sobre a pressão arterial, freqüência cardíaca, tolerância ao esforço, consumo de oxigênio (VO2), morfologia e bioquímica da musculatura esquelética foram estudados em ratos espontaneamente hipertensos (SHR, n=28) e Wistar Kyoto (WKY, n=28) com 12 semanas de vida e divididos em 4 grupos: SHR, SHR treinado (SHR-T), WKY e WKY Treinado (WKY-T). O TF promoveu redução da pressão arterial em SHR e bradicardia de repouso acompanhado por um aumento da atividade da citrato sintase muscular, tolerância ao esforço e VO2 nos grupos de animais treinados. Concomitantemente, o TF corrigiu a alteração na distribuição dos tipos de fibra muscular e a rarefação capilar em SHR, mediado em grande parte por um aumento nos níveis protéicos periféricos de VEGF, VEGFR2, eNOS e a desativação das vias de apoptose. O número de CPE (CD34+/Flk1+) no sangue periférico (SP) analisadas por FACS foram aumentadas 115% no grupo WKY-T em comparação ao grupo controle. Em contraste, o grupo SHR reduziu 39% o número de CPE, entretanto o TF normalizou os níveis no grupo SHR-T. Resultado similar foi encontrado na quantificação das CPE na medula óssea (MO) avaliadas por células duplamente positivas para Di-acLDL e Lectina-FITC. A senescência das CPE na MO foi aumentada 126% no grupo SHR vs. WKY, e o TF foi eficiente em reduzir 72% este processo no grupo SHR-T. Além disso, os ensaios funcionais avaliados pelo número de unidades formadoras de colônia mostraram um aumento de 40% na MO e 70% no SP de WKY-T vs. WKY. Em contraste, a HA reduziu 35% na MO e 45% no SP este número de colônias vs. WKY, porém o TF corrigiu esta disfunção das CPE na HA. De fato, o TF recuperou a falha na formação de tubos como capilares sobre matrigel na HA. Os resultados demonstram que o remodelamento vascular acompanhado pela redução da pressão arterial induzido pelo TF na HA ocorreram em sinergia com a recuperação do número e das propriedades funcionais das CPE da MO e SP, bem como de seus fatores mobilizadores e angiogênicos. Estes resultados sugerem que o TF pode participar do reparo vascular por meio da ação das CPE, promovendo a revascularização periférica. Assim, há perspectiva do potencial terapêutico das CPE no tratamento da HA pós TF. / Aerobic exercise training (ET) has been established as an important non-pharmacological treatment for hypertension, since it counteracts microvascular rarefaction and decreased blood pressure; however, underlying mechanisms remain to be further determined. We investigated for the first time if the endothelial progenitor cells (EPC) number and the functional capacity, impaired in hypertension; are improved after ET potentially contributing to neovascularization and disease regression. The effect of ET on blood pressure, heart rate, exercise tolerance, peak VO2 and skeletal muscle morphology and biochemistry was studied in twelve-week old male Spontaneously Hypertensive Rats (SHR, n=28) and Wistar Kyoto (WKY, n=28) assigned into 4 groups: SHR, trained SHR (SHR-T), WKY and trained WKY (WKY-T). The ET promoted a decrease in blood pressure in SHR and resting bradycardia, an increase in exercise tolerance, peak VO2 and citrate synthase activity in trained groups. In parallel, the ET repaired the skeletal muscle fiber type shift and capillary rarefaction in SHR, at least partly, by enhancing protein levels of VEGF, VEGFR-2, eNOS and deactivated apoptosis pathway. Numbers of EPC (CD34+/Flk1+) in the peripheral blood (PB) quantified by FACS analysis were enhanced 115% in WKY-T of control levels. In contrast, the SHR group decreased 39%, but ET normalized in the SHR-T. Similar results were found in the EPC quantification of the bone marrow (BM) by double positive cells to Di-acLDL and Lectin-FITC. BM-EPC senescence was increased 126% in SHR and this process was reduced 72% by ET. Moreover, EPC functional assay by colony-forming units showed an increase of 40% to BM and 70% to PB in WKY-T of control levels. In contrast, the SHR group reduced 35% to BM and 45% to PB; however the ET repaired EPC dysfunction in hypertension. In fact, the ET corrected failure in the capillary-like tube formation on matrigel. The present findings reveal that the vascular remodeling accompanied by reduction of blood pressure induced by ET occurs in synergy with the restoration of the BM and PB- EPC number and functional properties, as well as of their mobilizing and angiogenic factors. These results suggest that the ET can participate in the vascular repair by means of the EPC, promoting the peripheral revascularization in hypertension. In this way, there is perspective of therapeutic potential of the EPC in treatment of hypertension after ET.

Selon les lignes directrices chez les patients coronariens, un programme d’entrainement aérobie doit combiner de l’entrainement continu à intensité modérée (ECIM) et par intervalles à haute intensité (EIHI), en étant progressif et structuré (périodisation linéaire [PL]), et manipulé selon les principes FITT qui incluent la fréquence, l’intensité, la durée, et la modalité (ou le type). Contrairement à la PL où la charge d’entrainement est constamment augmentée, la périodisation non-linéaire (PNL) de l’entrainement consiste à incorporer des périodes de récupération au cours d’un cycle d’entrainement afin d’optimiser les adaptations et d’éviter la monotonie et le surmenage. Chez les individus sains et atteints de maladie pulmonaire obstructive chronique, la PNL de l’entrainement aérobie a parfois montré des bénéfices supérieurs à la PL sur l’amélioration de l’endurance aérobie. Notre objectif principal était donc de comparer la PNL à la PL de l’entrainement aérobie sur la fonction cardiorespiratoire chez des patients coronariens. Nous avons ensuite comparé les adaptations cardiaques pour les deux types de périodisation au niveau du ventricule gauche (VG) dans une deuxième étude. Nous avions comme hypothèse que la PNL de l’entrainement aérobie apporterait davantage de gains sur les paramètres de réponses cardiopulmonaires à l’effort comparativement à la PL. Un total de 39 patients coronariens stables, recrutés à l’Institut de Cardiologie de Montréal entre 2016 et 2018, ont effectué une épreuve cardiopulmonaire à l’effort avec mesure des échanges gazeux, et une échocardiographie de repos avant et après une intervention d’entrainement. Les mesures de fonction cardiorespiratoire comprenaient la consommation d’oxygène au pic de l’exercice (V̇O2pic), la puissance aérobie maximale, la ventilation minute (V̇E), les variables d’effort sous-maximales (pente d’efficacité de la consommation d’oxygène PECO], pente de ventilation sur la production de dioxyde de carbone [V̇E/V̇CO2]), les consommations d’oxygène aux 1er [SV1] et 2e [SV2] seuils ventilatoires), et le pouls en oxygène (pouls en O2). Nous avons également mesuré la proportion de hauts et faibles répondeurs dans chacun des groupes selon la médiane du delta V̇O2pic. Les mesures d’échocardiographie comprenaient des mesures de la fonction systolique et diastolique, et des mesures de déformation de la paroi du VG. Les participants ont été répartis aléatoirement soit dans le groupe PL (n = 20, 65±10 ans), soit dans le groupe PNL (n = 19, 66±5 ans) pour 3 mois d’entrainement. L’entrainement consistait à 3 séances par semaine, pour les deux groupes, d’une durée de 30 à 60 minutes/séance, combinant de l’ECIM et de l’EIHI progressifs périodisés, ainsi que des exercices en résistance similaires non progressifs. Bien que les deux groupes étaient isoénergétiques (dépense énergétique totale équivalente sur 12 semaines), la dépense énergétique hebdomadaire était constamment augmentée dans le groupe PL, alors qu’elle était augmentée plus rapidement et entrecoupée d’une semaine d’entrainement à charge plus légère toutes les 4 semaines dans le groupe PNL. Nous avons observé une augmentation similaire du V̇O2pic, V̇E, PECO, VT1 et SV2, pouls en O2, de la fraction d’éjection du VG , la déformation radiale, et la vitesse de déformation radiale du VG (interaction tempsgroupe : p > 0,05 ; effet du temps : p < 0,05) entre les 2 groupes. La proportion de non, faibles et hauts répondeurs était similaire entre les 2 groupes (p = 0,29). Cependant, la fonction diastolique n’a pas évolué après les 12 semaines d’entrainement dans aucun des deux groupes. Nos résultats suggèrent que dans cette population, une variation accrue de la charge par la périodisation non-linéaire d’entrainement ne procure pas de gain additionnel dans la réponse cardiopulmonaire à l’effort et dans la fonction cardiaque de patients coronariens. Bien qu’il ne s’agisse pas d’une comparaison directe, une autre étude a rapporté une proportion de 37 % de hauts répondeurs auprès de 1171 patients coronariens après un programme d’entrainement non périodisé de 3 mois, comparativement à 60 et 47 % dans nos groupes PL et PNL, respectivement. Sachant que la non-réponse à l’entrainement est associée à une plus grande mortalité à long-terme, davantage d’études sont nécessaires afin de déterminer si la périodisation de l’entrainement (PL ou PNL) peut mener à une réponse à l’entrainement plus grande et être incorporée dans les programmes de réadaptation cardiaque. / Guidelines on exercise training in patients with coronary heart disease (CHD)suggest that an exercise training program with should combine moderate-intensity continuous (MICT) with a high-intensity interval (HIIT) training, with a constant progressive and structured increase of the training load (linear periodization [LP]) in the course of the program. As opposed to the LP, non-linear periodization (NLP) is characterized by greater increase of the training load intercepted by one training week with a lighter training load. NLP is used in athletes to bring variation in the training load, optimize training adaptation, avoid a plateau, monotony, and over-reaching. In healthy and individuals with chronic obstructive pulmonary disease, NLP showed greater improvement in aerobic endurance. Our main objective was to compare the NLP with the LP protocol on the cardiopulmonary exercise response in patients with CHD. Then, we compared the cardiac adaptation of the left ventricle (LV) between both aerobic training periodization. We hypothesized that NLP will be superior for improving cardiorespiratory parameters compared to LP. We recruited 39 patients with stable CHD from the Montreal Heart Institute, between 2016 and 2018. All completed a maximal cardiopulmonary exercise testing (CPET) with gas exchange measurements and a resting cardiac echography before and after the training intervention. The CPET measurements included peak oxygen uptake (peak V̇O2), oxygen uptake efficiency slope (OUES), minute ventilation (V̇E), ventilatory efficiency slope (V̇E/V̇CO2 slope), oxygen uptake at the first (VT1) and second (VT2) ventilatory thresholds, and oxygen pulse (O2pulse). We also assessed the proportion of non, low, and high responders between both aerobic training periodization using the median of the delta peak V̇O2. The cardiac function measurements included the systolic and the diastolic functions, and the myocardial strain and strain rates in the LV. Exercise training protocols included 3 sessions/week, for 30 to 60 minutes/session, combining a periodized HIIT and MICT, and a non-periodized resistance training. Weekly energy expenditure was constantly increased in the LP group for the aerobic training, while it was increased and intercepted with a lighter training load week each fourth week in the NLP group. VI We observed a similar improvement in both groups for peak V̇O2, OUES, VT1, VT2, O2pulse, 3-dimensional LV ejection fraction, radial strain and radial strain rates, (interaction time*group : p>0.05 ; time effect : p<0.05 with a superior effect size in the LP group). Proportion of high responders was similar between groups (p=0.29). Our results suggest that incorporating more training load variation does not bring more training adaptation in an exercise training program in patients with stable CHD. Despite it is not a direct comparison, another study showed a proportion of 37% of non-responders after a non-periodized training program in 1,171 patients with CHD, compared to 60 and 47% in the LP and NLP from our study, respectively. More studies are needed to examine if training periodization could lead to an increased training response and could be integrated in cardiac rehabilitation programs.