O 4-hidroxi-2-nonenal (4-HNE) é um dos principais produtos da peroxidação lipídica, processo exacerbado no quadro de estresse oxidativo. Em função de sua alta reatividade com biomoléculas, seu acúmulo tem sido relacionado ao estabalecimento e progressão de inúmeras doenças, incluindo as cardiovasculares. Recentemente, nosso grupo identificou a interação entre 4-HNE e a proteína Dicer em coração de ratos com insuficiência cardíaca (dados não publicados). Dicer é uma RNAse importante na biogênese de microRNAs (miRNA), com papel na regulação gênica póstranscricional, de modo que alterações em sua função poderiam afetar diversos processos celulares. Tanto a interação entre o aldeído e Dicer, quanto o efeito sobre a mesma não foram descritos na literatura. Nesse contexto, o presente estudo tem como objetivo avaliar o efeito do 4-HNE na atividade e a expressão da Dicer. Nossa hipótese é que o 4-HNE afete negativamente o perfil de atividade e expressão da Dicer. Para testar essa hipótese, utilizamos o modelo animal de disfunção cardíaca induzida cirurgicamente e avaliamos: a formação de adutos de 4-HNE-proteínas, atividade e expressão de Dicer, e os níveis de miRNAs cardíacos. Em cultura celular (H9C2, MEF e HEK293), por sua vez, avaliamos o efeito agudo de 4-HNE sobre as mesmas variáveis após sua adição no meio de cultura. E, por último, utilizando a proteína recombinante, analisamos o efeito direto do aldeído sobre a estabilidade e atividade da enzima in vitro. Como esperado, em ensaios com a proteína isolada, observamos que o 4-HNE interage diretamente com a RNAse Dicer, e a formação de conjugados Dicer-4-HNE é responsável pela inibição e perda de estabilidade da proteína de forma tempo- e concentração-dependentes. No modelo animal, demonstramos um prejuízo na atividade de Dicer no coração de animais com disfunção cardíaca induzida por infarto do miocárdio, sem alteração em sua expressão, acompanhado de diminuição dos níveis da maioria dos miomiRs analisados. Notavelmente, ambos os parâmetros, assim como os níveis de adutos de 4-HNE-proteínas, foram melhorados no grupo tratado com Alda-1, agonista alostérico da enzima ALDH2 (responsável pela remoção do 4-HNE). Dessa forma, sugerimos a existência de associação entre os níveis de 4-HNE, atividade de Dicer e alteração na expressão de miRNAs no quadro de disfunção cardíaca. Consistente com os dados observados in vivo, em modelos celulares, a exposição aguda ao 4-HNE demonstrou reduzir a atividade de Dicer e afetar a via de biossíntese de miRNAs. Porém, não observamos proteção por Alda nesse modelo. Conjuntamente, nossos dados sugerem que a atividade de Dicer é modulada por 4-HNE em quadros de estresse agudo e crônico de aldeídos. Contudo, mais estudos são necessários a fim de elucidar o mecanismo pelo qual essa modulação ocorre. Visto que o acúmulo de 4-HNE e a desregulação na biogênese de miRNAs tem sido associados ao desenvolvimento de patologias, o estudo da interação entre Dicer e o aldeído é importante na compreensão dessas doenças e planejamento de novas estratégias terapêuticas. / 4-hydroxy-2-nonenal (4-HNE) is a major by-product of lipid peroxidation, a process that is exacerbated under oxidative stress conditions. This aldehyde is a very reactive molecule associated with the establishment and progression of many diseases, including cardiovascular diseases. We recently found using proteomics that 4-HNE directly targets Dicer in failing hearts, a critical enzyme for miRNA biology (unpublished data). Neither the aldehyde-Dicer adduction, nor its effect on protein stability and activity has been previously reported. Therefore, this study aimed to fill this gap by further investigating 4-HNE-Dicer interaction and characterizing its effect on Dicer profile. We hypothesize that 4-HNE will make adducts with Dicer and compromise its function and levels. Using an animal model of cardiac dysfunction, we evaluated the following parameters: levels of 4-HNE adducted proteins, Dicer levels and activity, and the levels of heart specific miRNAs (myomiRs). The same variables were analyzed in distinct cellular models (H9C2, MEF, HEK293) after acute exposure to 4-HNE. Additionally, we synthetized recombinant Dicer, and protein function and stability were assessed in vitro. As expected, the experiments with recombinant protein revealed that 4-HNE directly interacts with Dicer, and the formation of 4-HNE-DICER adduct causes loss of Dicer cleavage activity and stability in a time- and concentration-dependent manner. Regarding the animal model, Dicer activity, but not protein levels, dropped in failing hearts, which was paralleled by a reduction of mature miRNA levels. Of interest, animals with cardiac dysfunction chronically treated with a small molecule activator of aldehyde dehydrogenase 2 (ALDH2), termed Alda-1, displayed an elevated cardiac Dicer activity and mature miRNA levels compared with vehicle-treated animals. ALDH2 is the mains enzyme responsible for 4-HNE clearance. In this context, this study points out a potential connection among 4-HNE levels, Dicer activity and myomiR levels in cardiac dysfunction. Consistent with our in vivo data, cells acutely exposed to 4-HNE showed an increase in 4-HNE-protein adducts followed by a reduction in Dicer activity and changes in miRNA biosynthesis. However, Alda showed no protective effect in the latter model. Taken together, our findings using animal and cellular models suggest that Dicer activity is impaired in chronic (cardiac dysfunction) and acute aldehyde stress conditions. However, the molecular mechanisms involved in this response are still unclear. As both 4-HNE accumulation and microRNAs have been linked to innumerous pathologies, clarifying the modulation of Dicer activity under such conditions will certainly contribute to a better understanding the diseases and future therapeutic strategies.

Since 1933, studies have explored the concept of trauma induced secondary cardiac injury (TISCI), yet till 2012, it had not been defined as the incidence of cardiac events and rise in cardiac biomarkers following traumatic injury. Despite, improvements in early outcomes, trauma patients have reduced long-term mortality with cardiac disease being the major contributor. Although many putative mechanisms have been suggested for TISCI, the underpinning pathophysiology still remains unclear. In this thesis, a prospective study of 290 critically injured patients identifies a 13% incidence of adverse cardiac events (ACE) with consistently raised serum h-FABP levels in these patients. H-FABP was found to be a good predictor of ACE through ROC analysis and a h-FABP of 16.8 ng/ml used to define trauma induced secondary cardiac injury (TISCI). TISCI was associated with longer hospital stay and higher mortality. Patients who developed ACE had higher plasma levels of adrenaline and noradrenaline with a correlating increase in plasma h-FABP. On multivariate analysis, hypertension was the only independent risk factors for ACE. The increase in serum cardiac biomarkers was reflected by an increase in serum h- FABP in our group's trauma hemorrhage murine models. The hearts of these models were used in the experiments that form the last experimental chapter of this thesis. Protein expression studies confirm this increase in serum h-FABP by evidence of concurrent leaching in the cardiac tissue, along with Troponin I. Myocardial injury was evident on electron microscopy with evidence of interstitial and organelle oedema, myofibrillar degeneration, nuclear condensation and changes in mitochondrial morphology. Immunohistochemistry and western blotting protein studies demonstrate the translocation of the mitochondrial death-related protein AIF to the cytosol and nucleus, where it becomes its active pro-apoptotic form. This thesis propositions the utility of the cardiac biomarker h-FABP in predicting ACE and outcomes in critically injured patients. Although increasing serum noradrenaline and adrenaline levels are associated with higher incidence of ACE and biochemical evidence of cardiac injury with rising h-FABP levels, multivariate analysis negates their value as independent predictors of ACE. Leaching out of the proteins h-FABP and Troponin I in the murine cardiac tissue confirmed the value of serum measurements of these proteins as markers of cardiac injury. This was associated with widespread ultrastructural myocardial damage in the TH mice with changes in mitochondrial morphology. The mitochondrial damage seen is associated with the translocation of the mitochondrial death-related protein AIF to the cytosol and the nucleus where I propose its canonical signaling leading to nuclear degradation and cell death is the driver of cardiac dysfunction.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Indivíduos obesos apresentam maior risco de morbidade e mortalidade atribuída às doenças cardiovasculares. A composição da dieta é um fator que prediz o fenótipo cardíaco em resposta a obesidade e, o tipo de ácido graxo pode afetar de forma diferencial a estrutura e a função do miocárdio. Estudos têm mostrado que a disfunção mitocondrial exerce um papel chave na patogênese da insuficiência e hipertrofia cardíaca, e as alterações mitocondriais observadas em falhas cardíacas apontam para defeitos em sítios específicos da cadeia transportadora de elétrons. Desta forma, o objetivo deste estudo foi avaliar a função contrátil ventricular em camundongos, alimentados com dieta hiperlipídica, rica em ácidos graxos poliinsaturados, buscando elucidações através da bioenergética mitocondrial. Após desmame, camundongos machos C57Bl/6 passaram a receber dieta manipulada contendo 7% (C) ou 19% (HF) de óleo de soja, até os 135 dias de idade. A ingestão alimentar e a massa corporal foram monitoradas e foi realizado teste de tolerância à glicose. No final do período experimental, os animais foram anestesiados e submetidos à avaliação da composição corporal por Absortimetria de Raios X de Dupla Energia (DXA), e em seguida, sacrificados por exsanguinação. No plasma foram determinados o perfil lipídico e a insulina. O coração, o tecido adiposo intra-abdominal e o subcutâneo foram coletados, pesados, processados para análise histomorfológica. Fibras cardíacas do ventrículo esquerdo foram utilizadas para análise da respiração mitocondrial através de oxígrafo. O coração também foi utilizado para a técnica de perfusão de coração isolado de Langendorff, e para análise da expressão de proteínas relacionadas à bioenergética de cardiomiócitos, através de Western Blotting. O índice de HOMA e de adiposidade foram calculados. O grupo HF apresentou maior adiposidade, sem alteração na ingestão alimentar. Foi observada intolerância a glicose, hiperinsulinemia e resistência à insulina, além de alterações desfavoráveis no perfil lipídico. Foi observado alteração na morfologia cardíaca e quadro de cardiomiopatia hipertrófica, refletindo em alteração hemodinâmica, determinando maior contratilidade, maior pressão ventricular e função diastólica prejudicada. Em relação à atividade mitocondrial dos cardiomiócitos foi observada menor oxidação de carboidratos (-47%) e de ácidos graxos (-60%). Porém, sem alteração na expressão de proteínas relacionadas à bioenergética de cardiomiócitos, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK. A partir desses resultados, concluímos que o tipo e a quantidade de ácidos graxos predizem o fenótipo cardíaco na obesidade, promovendo alteração na capacidade oxidativa mitocondrial, na morfologia e na hemodinâmica cardíaca / Obese individuals have a higher risk of morbidity and mortality attributed to cardiovascular disease. The diet composition is one factor that predicts the cardiac phenotype in response to obesity and the type of fatty acid differentially influences the myocardial structure and function. Studies have showed that mitochondrial dysfunction is considered to play a key role in the pathogenesis of cardiac hypertrophy and failure, also the mitochondrial alterations present in heart failure indicate to defects at specific sites in electron transport chain. Thus, the aim of the study was evaluated the ventricular contractile function in mice fed high fat diet, rich in polyunsaturated fatty acids, looking through mitochondrial bioenergetics. After weaning, mouse C57Bl/6 received manipulated diet containing 7% (C) or 19% (HF) of soybean oil, until 135 days of age. The food intake and the body mass were monitored, and the glucose tolerance test was realized. At the end of the experimental period, the animals had their body composition evaluated by Dual-energy X-ray Absorptiometry (DXA), after, were sacrificed by exsanguination. In plasma was determined the lipid profile and insulin. The heart, intraabdominal and subcutaneous adipose tissue were collected, weighted and processed to morphological analysis. The left ventricular myocardial fibers were used to analyze mitochondrial respiration by technique of high resolution respirometry. The heart was used to the Langendorff technique of isolated heart perfusion, and to analyze the expression of proteins related to the cardiomyocytes bioenergetics, through of Western Blotting. The HOMA-IR and the adiposity index were calculated. The group HF showed higher adiposity, but did not differ about food intake. Was observed glucose intolerance, hiperinsulinemia, insulin resistance and also unfavorable alterations in lipid profile. Was observed alterations in cardiac morphology and hypertrophic cardiomyopathy, reflecting in hemodinamic alterations with increase of contractility, higher ventricular pressure and impaired diastolic function. About the mitochondrial activity of cardiomyocytes was observed lower oxidation of carbohydrates (-47%) and fatty acids (-60%). However, the expression of proteins related to the cardiomyocytes bioenergetics, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK, did not differ between the groups. From these results, we conclude that the type and amount of fatty acids predict the cardiac phenotype in obesity, promoting the impairment of mitochondrial oxidative capacity, alterations in cardiac morphology and hemodynamics

Diabetic cardiomyopathy characterized by left ventricular hypertrophy predisposes diabetic and obese individuals to development of cardiac dysfunction and subsequently to heart failure. Whether hyperinsulinemia has an underlying role in development and or progression of diabetic heart disease is not well understood. We therefore studied the effects of acute hyperinsulinemia on cardiac function in euglycemic states. Acute hyperinsulinemia neither affected baseline nor inotropic response to β-adrenergic stimulation. Previous studies from our laboratory have indicated a potential role for GRK2, a serine threonine kinase in development of cardiac dysfunction in diabetic states in humans as well as in mice. To assess whether GRK2 mediates the detrimental effects of chronic hyperinsulinemia on cardiac dysfunction in mouse model of diet induced obesity, we utilized cardiomyocyte knockout of GRK2. Our results suggested lack of cardiac functional impairments in high fat fed wildtype mice, which hindered our attempts to ascertain the role of GRK2 in diabetic cardiomyopathy. Mouse models of diet induced obesity have been routinely used to study the effects of obesity and diabetes on cardiac dysfunction but recent evidence from multiple research groups has emphasized the need for evaluation of the utility and relevance of the murine diet induced obesity model for studying cardiovascular abnormalities associated with hyperinsulinemic states, including T2DM and obesity. We therefore studied the effect of chronic fat feeding (>20 weeks) alone or in combination with concomitant hypertension on cardiac function in C57BL/6J mice. Different diets were formulated with either lard (32% saturated fat, 68% unsaturated fat) or hydrogenated coconut oil (95% saturated fat) as the source of fat and fatty acids, which contributed 60% of total calories. Insulin resistance and glucose intolerance were readily observed in mice fed a high fat diet in each of the studies. HFD resulted in the development of cardiac hypertrophy; however cardiac function as measured by B-mode echocardiography and LV catheterization was unaffected in high fat diet groups compared to their respective control diet groups. Further, dietary fat feeding regardless of the source of fat modestly altered the gene expression of a few pathological hypertrophic markers or of fibrosis related genes. However, there was an increase in expression of PPARa target genes such as Pdk4 and fatty acid metabolism genes including CD36, AcadL and Cpt1b. Cardiac mitochondrial function as assessed by oxygen consumption rates, ATP synthesis rates and reactive oxygen species production rates were unaltered in high fat diet fed mice. These results suggest that while chronic fat feeding in mice causes cardiac hypertrophy and potentially cardiometabolic remodeling, it might not be sufficient to activate pathological hypertrophic mechanisms that impair cardiac function and cause cardiac fibrosis.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Indivíduos obesos apresentam maior risco de morbidade e mortalidade atribuída às doenças cardiovasculares. A composição da dieta é um fator que prediz o fenótipo cardíaco em resposta a obesidade e, o tipo de ácido graxo pode afetar de forma diferencial a estrutura e a função do miocárdio. Estudos têm mostrado que a disfunção mitocondrial exerce um papel chave na patogênese da insuficiência e hipertrofia cardíaca, e as alterações mitocondriais observadas em falhas cardíacas apontam para defeitos em sítios específicos da cadeia transportadora de elétrons. Desta forma, o objetivo deste estudo foi avaliar a função contrátil ventricular em camundongos, alimentados com dieta hiperlipídica, rica em ácidos graxos poliinsaturados, buscando elucidações através da bioenergética mitocondrial. Após desmame, camundongos machos C57Bl/6 passaram a receber dieta manipulada contendo 7% (C) ou 19% (HF) de óleo de soja, até os 135 dias de idade. A ingestão alimentar e a massa corporal foram monitoradas e foi realizado teste de tolerância à glicose. No final do período experimental, os animais foram anestesiados e submetidos à avaliação da composição corporal por Absortimetria de Raios X de Dupla Energia (DXA), e em seguida, sacrificados por exsanguinação. No plasma foram determinados o perfil lipídico e a insulina. O coração, o tecido adiposo intra-abdominal e o subcutâneo foram coletados, pesados, processados para análise histomorfológica. Fibras cardíacas do ventrículo esquerdo foram utilizadas para análise da respiração mitocondrial através de oxígrafo. O coração também foi utilizado para a técnica de perfusão de coração isolado de Langendorff, e para análise da expressão de proteínas relacionadas à bioenergética de cardiomiócitos, através de Western Blotting. O índice de HOMA e de adiposidade foram calculados. O grupo HF apresentou maior adiposidade, sem alteração na ingestão alimentar. Foi observada intolerância a glicose, hiperinsulinemia e resistência à insulina, além de alterações desfavoráveis no perfil lipídico. Foi observado alteração na morfologia cardíaca e quadro de cardiomiopatia hipertrófica, refletindo em alteração hemodinâmica, determinando maior contratilidade, maior pressão ventricular e função diastólica prejudicada. Em relação à atividade mitocondrial dos cardiomiócitos foi observada menor oxidação de carboidratos (-47%) e de ácidos graxos (-60%). Porém, sem alteração na expressão de proteínas relacionadas à bioenergética de cardiomiócitos, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK. A partir desses resultados, concluímos que o tipo e a quantidade de ácidos graxos predizem o fenótipo cardíaco na obesidade, promovendo alteração na capacidade oxidativa mitocondrial, na morfologia e na hemodinâmica cardíaca / Obese individuals have a higher risk of morbidity and mortality attributed to cardiovascular disease. The diet composition is one factor that predicts the cardiac phenotype in response to obesity and the type of fatty acid differentially influences the myocardial structure and function. Studies have showed that mitochondrial dysfunction is considered to play a key role in the pathogenesis of cardiac hypertrophy and failure, also the mitochondrial alterations present in heart failure indicate to defects at specific sites in electron transport chain. Thus, the aim of the study was evaluated the ventricular contractile function in mice fed high fat diet, rich in polyunsaturated fatty acids, looking through mitochondrial bioenergetics. After weaning, mouse C57Bl/6 received manipulated diet containing 7% (C) or 19% (HF) of soybean oil, until 135 days of age. The food intake and the body mass were monitored, and the glucose tolerance test was realized. At the end of the experimental period, the animals had their body composition evaluated by Dual-energy X-ray Absorptiometry (DXA), after, were sacrificed by exsanguination. In plasma was determined the lipid profile and insulin. The heart, intraabdominal and subcutaneous adipose tissue were collected, weighted and processed to morphological analysis. The left ventricular myocardial fibers were used to analyze mitochondrial respiration by technique of high resolution respirometry. The heart was used to the Langendorff technique of isolated heart perfusion, and to analyze the expression of proteins related to the cardiomyocytes bioenergetics, through of Western Blotting. The HOMA-IR and the adiposity index were calculated. The group HF showed higher adiposity, but did not differ about food intake. Was observed glucose intolerance, hiperinsulinemia, insulin resistance and also unfavorable alterations in lipid profile. Was observed alterations in cardiac morphology and hypertrophic cardiomyopathy, reflecting in hemodinamic alterations with increase of contractility, higher ventricular pressure and impaired diastolic function. About the mitochondrial activity of cardiomyocytes was observed lower oxidation of carbohydrates (-47%) and fatty acids (-60%). However, the expression of proteins related to the cardiomyocytes bioenergetics, CPT1, UCP2, GLUT1, GLUT4, AMPK e pAMPK, did not differ between the groups. From these results, we conclude that the type and amount of fatty acids predict the cardiac phenotype in obesity, promoting the impairment of mitochondrial oxidative capacity, alterations in cardiac morphology and hemodynamics

Introduction: Cardiometabolic syndrome is considered a chronic low-grade inflammatory condition that affects various organs and tissues. Individuals with type 2 diabetes mellitus (T2DM) and obesity are at an increased risk for developing the cardiometabolic syndrome and have greater rates of cardiovascular disease (CVD). These conditions are also associated with increased systemic and local inflammation and greater expression of pro-inflammatory markers such as monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) in many tissues. The heart is adversely affected by the inflammation and metabolic changes induced by diabetes and obesity. Nuclear transcription factor kappa B (NF-κB) activity is known to be related to inflammation and cytokine production. However, there is limited information on whether NF-κB signaling and inflammation play a role in early cardiac pathogenesis related to obesity and diabetes and whether lifestyle changes known to prevent or treat these diseases are effective in the heart. Purpose: Therefore, the purpose of this study was to compare the effect of exercise (EX) and caloric restriction (CR) to alter NF-κB signaling, inflammation, and markers of cardiac dysfunction in the heart of 20-week old Otsuka Long Evans Tokushima (OLETF) rats. Methods: Hearts of male 20 week old OLETF rats from a previous study (Crissey et al., 2014) were collected for gene expression (RT-PCR), NF-κB activity, and markers of inflammation and immune cell infiltration. Results: There were no significant differences detected in markers of cardiac dysfunction including, α-MHC, β-MHC, ANP, BNP, COL1, COL3 (all p>0.05). Second, 1-way ANOVA showed that there was trend for an overall effect of group (p=0.07) on NF-κB activation where CR tended to be greater compared to SED and WR (p=0.06). Finally, there were no significant differences between groups in inflammatory and immune cell markers; CD4, F4/80, CD68, IL-1β, MCP-1, TGFB1, and TNF-α (all p>0.05). Conclusion: This study shows that at 20 weeks, a time when OLETF animals exhibit characteristics of the metabolic syndrome such as hypertension, mild obesity, and increased insulin resistance, EX and CR do not reduce markers of cardiac dysfunction and inflammation, potentially because inflammation does not influence the heart at this early time period in the development of the disease. Further, the trend of greater NF-κB activity in CR compared to EX and SED, needs further exploration.

Cardiac dysfunction is correlated with detrimental prognosis of sepsis and contributes to a high risk of mortality. After an initial hyperinflammatory reaction, most patients enter a protracted state of immunosuppression (late sepsis) that alters both innate and adaptive immunity. The changes of cardiac function in late sepsis are not yet known. MicroRNA-155 (miR-155) is previously found to play important roles in both regulations of immune activation and cardiac function. In this study, C57BL/6 mice were operated to develop into early and late sepsis phases, and miR-155 mimic was injected through the tail vein 48 h after cecal ligation and puncture (CLP). The effect of miR-155 on CLP-induced cardiac dysfunction was explored in late sepsis. We found that increased expression of miR-155 in the myocardium protected against cardiac dysfunction in late sepsis evidenced by attenuating sepsis-reduced cardiac output and enhancing left ventricular systolic function. We also observed that miR-155 markedly reduced the infiltration of macrophages and neutrophils into the myocardium and attenuated the inflammatory response via suppression of JNK signaling pathway. Moreover, overexpression of β-arrestin 2 (Arrb2) exacerbated the mice mortality and immunosuppression in late sepsis. Furthermore, transfection of miR-155 mimic reduced Arrb2 expression, and then restored immunocompetence and improved survival in late septic mice. We conclude that increased miR-155 expression through systemic administration of miR-155 mimic attenuates cardiac dysfunction and improves late sepsis survival by targeting JNK associated inflammatory signaling and Arrb2 mediated immunosuppression.

AimsHSPA12B is a newly discovered and endothelial-cell-specifically expressed heat shock protein. We have reported recently that overexpression of HSPA12B increased endothelial nitric oxide synthase (eNOS) expression in mouse cardiac tissues during endotoxemia. Endothelial NOS has been shown to protect heart from ischaemic injury. We hypothesized that overexpression of HSPA12B will attenuate cardiac dysfunction and remodelling after myocardial infarction (MI) through an eNOS-dependant mechanism.Methods and resultsMI was induced by permanent ligation of the left anterior descending coronary artery in the transgenic mice (Tg) overexpressing hspa12b gene and its wild-type (WT) littermates. Echocardiographic analysis revealed that Tg mice exhibited improvements in cardiac dysfunction and remodelling at 1 and 4 weeks after MI. These improvements were accompanied by a significant decrease in cardiomyocyte apoptosis and increase in capillary and arteriolar densities. Significant up-regulation of eNOS, VEGF, Ang-1, and Bcl-2 was also observed in Tg hearts compared with WT hearts after MI. However, pharmacological inhibition of eNOS abolished the HSPA12B-induced decrease in cardiomyocyte apoptosis and increase in capillary formation after MI. Most importantly, inhibition of eNOS abrogated the protection of HSPA12B against cardiac dysfunction and remodelling after MI.ConclusionsThese data demonstrate for the first time that the overexpression of HSPA12B attenuates cardiac dysfunction and remodelling after MI. This action of HSPA12B was mediated, at least in part, by prevention of cardiomyocyte apoptosis and promotion of myocardial angiogenesis via an eNOS-dependent mechanism. HSPA12B could be a novel target for the management of patients with post-MI cardiac dysfunction and remodelling.

Myocardial dysfunction is an important manifestation of sepsis/septic shock. Activation of Phosphatidylinositol 3-kinase(PI3K)/protein kinase B (Akt) signaling pathway has been shown to improve cardiac performance during sepsis/septic shock. We have reported previously that α-lipoic acid (LA) activates PI3K/Akt pathway in neuronal cells. It is possible, therefore, that treatment with LA will attenuate cardiac dysfunction during sepsis/septic shock through a PI3K/Akt-dependent mechanism. To test this possibility, we treated mice with LA prior to lipopolysaccharide (LPS) challenge. Cardiac function was analyzed by echocardiography 6 h after LPS challenge. LPS significantly suppressed cardiac function as evidenced by decreases in EF% and FS% in mice. However, LA pretreatment significantly attenuated cardiac dysfunction following LPS challenge. LA pretreatment also improved survival in LPS-challenged mice. Furthermore, LA markedly attenuated the LPS-induced inflammatory response in myocardium, as evidenced by decreases in the upregulation of VCAM-1, ICAM-1 and iNOS, as well as myocardial leucocytes infiltration. Moreover, LPS challenge significantly decreased the phosphorylation levels of Akt and Gsk-3β, which was prevented by LA pretreatment. More importantly, inhibition of PI3K/Akt signaling by Wortmannin (WM) completely abrogated the LA-induced protection in cardiac dysfunction following LPS challenge. Collectively, our results demonstrated that LA improved cardiac function during endotoxemia. The mechanism was through, at least in part, preserved activation of the PI3K/Akt signaling.

AimsHSPA12B is a newly discovered and endothelial-cell-specifically expressed heat shock protein. We have reported recently that overexpression of HSPA12B increased endothelial nitric oxide synthase (eNOS) expression in mouse cardiac tissues during endotoxemia. Endothelial NOS has been shown to protect heart from ischaemic injury. We hypothesized that overexpression of HSPA12B will attenuate cardiac dysfunction and remodelling after myocardial infarction (MI) through an eNOS-dependant mechanism.Methods and resultsMI was induced by permanent ligation of the left anterior descending coronary artery in the transgenic mice (Tg) overexpressing hspa12b gene and its wild-type (WT) littermates. Echocardiographic analysis revealed that Tg mice exhibited improvements in cardiac dysfunction and remodelling at 1 and 4 weeks after MI. These improvements were accompanied by a significant decrease in cardiomyocyte apoptosis and increase in capillary and arteriolar densities. Significant up-regulation of eNOS, VEGF, Ang-1, and Bcl-2 was also observed in Tg hearts compared with WT hearts after MI. However, pharmacological inhibition of eNOS abolished the HSPA12B-induced decrease in cardiomyocyte apoptosis and increase in capillary formation after MI. Most importantly, inhibition of eNOS abrogated the protection of HSPA12B against cardiac dysfunction and remodelling after MI.ConclusionsThese data demonstrate for the first time that the overexpression of HSPA12B attenuates cardiac dysfunction and remodelling after MI. This action of HSPA12B was mediated, at least in part, by prevention of cardiomyocyte apoptosis and promotion of myocardial angiogenesis via an eNOS-dependent mechanism. HSPA12B could be a novel target for the management of patients with post-MI cardiac dysfunction and remodelling.