RESUMO
Aims: Myocardial ischaemia followed by reperfusion (IR) causes an oxidative burst resulting in cellular dysfunction. Little is known about the impact of oxidative stress on cardiomyocyte lipids and their role in cardiac cell death. Our goal was to identify oxidized phosphatidylcholine-containing phospholipids (OxPL) generated during IR, and to determine their impact on cell viability and myocardial infarct size. Methods and results: OxPL were quantitated in isolated rat cardiomyocytes using mass spectrophotometry following 24 h of IR. Cardiomyocyte cell death was quantitated following exogenously added OxPL and in the absence or presence of E06, a 'natural' murine monoclonal antibody that binds to the PC headgroup of OxPL. The impact of OxPL on mitochondria in cardiomyocytes was also determined using cell fractionation and Bnip expression. Transgenic Ldlr-/- mice, overexpressing a single-chain variable fragment of E06 (Ldlr-/--E06-scFv-Tg) were used to assess the effect of inactivating endogenously generated OxPL in vivo on myocardial infarct size. Following IR in vitro, isolated rat cardiomyocytes showed a significant increase in the specific OxPLs PONPC, POVPC, PAzPC, and PGPC (P < 0.05 to P < 0.001 for all). Exogenously added OxPLs resulted in significant death of rat cardiomyocytes, an effect inhibited by E06 (percent cell death with added POVPC was 22.6 ± 4.14% and with PONPC was 25.3 ± 3.4% compared to 8.0 ± 1.6% and 6.4 ± 1.0%, respectively, with the addition of E06, P < 0.05 for both). IR increased mitochondrial content of OxPL in rat cardiomyocytes and also increased expression of Bcl-2 death protein 3 (Bnip3), which was inhibited in presence of E06. Notably cardiomyocytes with Bnip3 knock-down were protected against cytotoxic effects of OxPL. In mice exposed to myocardial IR in vivo, compared to Ldlr-/- mice, Ldlr-/--E06-scFv-Tg mice had significantly smaller myocardial infarct size normalized to area at risk (72.4 ± 21.9% vs. 47.7 ± 17.6%, P = 0.023). Conclusions: OxPL are generated within cardiomyocytes during IR and have detrimental effects on cardiomyocyte viability. Inactivation of OxPL in vivo results in a reduction of infarct size.
Assuntos
Infarto do Miocárdio/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miócitos Cardíacos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Fosfolipídeos/metabolismo , Anticorpos de Cadeia Única/metabolismo , Animais , Morte Celular , Células Cultivadas , Modelos Animais de Doenças , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/patologia , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Infarto do Miocárdio/genética , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/patologia , Oxirredução , Ratos Sprague-Dawley , Receptores de LDL/genética , Receptores de LDL/metabolismo , Transdução de Sinais , Anticorpos de Cadeia Única/genéticaRESUMO
BACKGROUND: Cardio-Oncology is an evolving discipline that focuses on the management of cancer patients who develop cardiovascular complications as a result of their treatment. Although the current combination of surgical resection, radiation, and chemotherapy may lead to a cure in cancer patients, the administration of anti-cancer drugs, in particular Doxorubicin (DOX) and Trastuzumab (TRZ), is associated with an increased risk of cardiotoxicity. Little is known on the potential cardioprotective role of renin angiotensin system (RAS) antagonists in the prevention of DOX+TRZ mediated cardiotoxicity. OBJECTIVE: The aim of the study was to determine whether RAS antagonists would be useful in attenuating DOX+TRZ induced cardiotoxicity. METHODS: A total of 240 C57Bl/6 mice were randomized to prophylactic treatment with placebo, Aliskiren, Perindopril, or Valsartan for a total of 13 weeks. Within each arm, mice received treatment with either DOX, TRZ, or the combination of both drugs. Serial murine echocardiography was performed weekly to characterize the degree of cardiovascular remodeling within each group. RESULTS: In wild-type (WT) mice treated with DOX+TRZ, LV end diastolic internal diameter (LVID) increased from 3.1 ± 0.2 mm at baseline to 4.6 ± 0.3 mm at week 13 (p < 0.05) and the LV fractional shortening (FS) decreased from 52 ± 2% at baseline to 26 ± 2% at week 13 (p < 0.05). Prophylactic treatment with Aliskiren, Perindopril, or Valsartan attenuated the degree of LV cavity dilatation with LVID dimensions of 3.9 ± 0.2 mm, 4.1 ± 0.2 mm, and 4.2 ± 0.1 mm at week 13, respectively (p < 0.05). Similarly, prophylactic treatment with Aliskiren, Perindopril, or Valsartan was partially cardioprotective with FS of 40 ± 1%, 32 ± 1%, and 33 ± 2% at week 13, respectively (p < 0.05). As compared to WT mice receiving DOX+TRZ, prophylactic treatment with RAS inhibition was also associated with improved survival, corroborating the echocardiographic findings. CONCLUSION: The cardiotoxic effects of DOX+TRZ were partially attenuated by the prophylactic administration of RAS antagonists in a chronic murine model of chemotherapy induced cardiac dysfunction.
