RESUMO
Despite the use of rabbits in biomedical research, including regulatory toxicology and cardiovascular studies, little data exist on heart findings in this species. This study was designed to document myocardial findings in female rabbits and the impact of study-related procedures typical for vaccine toxicology studies. One hundred and forty 6- to 8-month-old female New Zealand White rabbits were divided equally into 2 groups, high and low study procedure groups (group 1 and group 2, respectively). All animals received intramuscular (IM) injections of sterile saline every 2 weeks for 5 times and were necropsied 2 days after the final IM injection. Clinical chemistry, hematology, and urinalysis were evaluated. Blood for stress biomarkers (norepinephrine, epinephrine, cortisol, and corticosterone), C-reactive protein, cardiac troponin I, and creatine kinase were collected at time 0 (just before dose administration) and then at 4, 24, and 48 hr after dose administration in group 1 only. Hearts were assessed histologically. Focal to multifocal minimal inflammatory cell infiltrates were common (â¼80%), particularly in the left ventricle and interventricular septum, and were similar to the types of infiltrates identified in other laboratory animal species. Additionally, study-related procedures elevated serum stress biomarkers and exacerbated the frequency and severity of myocardial inflammatory cell infiltrates.
Assuntos
Avaliação Pré-Clínica de Medicamentos , Macrófagos/imunologia , Miocárdio , Estresse Psicológico/imunologia , Testes de Toxicidade , Animais , Biomarcadores/sangue , Biomarcadores/urina , Catecolaminas/sangue , Catecolaminas/urina , Avaliação Pré-Clínica de Medicamentos/métodos , Feminino , Hidroxicorticosteroides/sangue , Hidroxicorticosteroides/urina , Injeções Intramusculares , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/patologia , Macrófagos/patologia , Miocárdio/citologia , Miocárdio/imunologia , Miocárdio/patologia , Miócitos Cardíacos/imunologia , Miócitos Cardíacos/patologia , Coelhos , Cloreto de Sódio/administração & dosagem , Especificidade da Espécie , Estresse Psicológico/patologia , Testes de Toxicidade/métodosRESUMO
Childhood obesity often leads to cardiovascular diseases, such as obesity-related cardiac hypertrophy (ORCH), in adulthood, due to chronic cardiac inflammation. Zinc is structurally and functionally essential for many transcription factors; however, its role in ORCH and underlying mechanism(s) remain unclear and were explored here in mice with obesity induced with high-fat diet (HFD). Four week old mice were fed on either HFD (60%kcal fat) or normal diet (ND, 10% kcal fat) for 3 or 6 months, respectively. Either diet contained one of three different zinc quantities: deficiency (ZD, 10mg zinc per 4057kcal), normal (ZN, 30mg zinc per 4057kcal) or supplement (ZS, 90mg zinc per 4057kcal). HFD induced a time-dependent obesity and ORCH, which was accompanied by increased cardiac inflammation and p38 MAPK activation. These effects were worsened by ZD in HFD/ZD mice and attenuated by ZS in HFD/ZS group, respectively. Also, administration of a p38 MAPK specific inhibitor in HFD mice for 3 months did not affect HFD-induced obesity, but completely abolished HFD-induced, and zinc deficiency-worsened, ORCH and cardiac inflammation. In vitro exposure of adult cardiomyocytes to palmitate induced cell hypertrophy accompanied by increased p38 MAPK activation, which was heightened by zinc depletion with its chelator TPEN. Inhibition of p38 MAPK with its specific siRNA also prevented the effects of palmitate on cardiomyocytes. These findings demonstrate that ZS alleviates but ZD heightens cardiac hypertrophy in HFD-induced obese mice through suppressing p38 MAPK-dependent cardiac inflammatory and hypertrophic pathways.
Assuntos
Cardiomegalia/prevenção & controle , Deficiências Nutricionais/dietoterapia , Suplementos Nutricionais , Sistema de Sinalização das MAP Quinases , Obesidade/fisiopatologia , Zinco/deficiência , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Cardiomegalia/etiologia , Cardiomegalia/metabolismo , Cardiomegalia/fisiopatologia , Células Cultivadas , Quelantes/efeitos adversos , Deficiências Nutricionais/complicações , Deficiências Nutricionais/imunologia , Dieta Hiperlipídica/efeitos adversos , Ativação Enzimática/efeitos dos fármacos , Ácidos Graxos não Esterificados/efeitos adversos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/imunologia , Miócitos Cardíacos/metabolismo , Obesidade/complicações , Obesidade/etiologia , Obesidade/imunologia , Ácido Palmítico/efeitos adversos , Inibidores de Proteínas Quinases/uso terapêutico , Interferência de RNA , Índice de Gravidade de Doença , Zinco/química , Zinco/uso terapêutico , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/genéticaRESUMO
Myocardial ischemia-reperfusion (MIR) injury is characterized by a rapid increase in cytokines and chemokines and an infiltration of inflammatory cells. Toll-like receptors (TLRs) 2 and 4 mediate these inflammatory responses. Herein we investigated the ability of Sparstolonin B (SsnB), a new selective TLR2/4 antagonist, to inhibit the TLR2/4-mediated inflammatory responses during cardiomyocyte hypoxia-reoxygenation injury as well as the responsible mechanisms. Lactate dehydrogenase (LDH) assay was performed to measure the cytotoxicity of SsnB on H9c2 cardiomyocytes. Quantitative real-time PCR (qRT-PCR) confirmed that TLR2 and TLR4 expression was elevated during hypoxia-reoxygenation, and that their up-regulation in cardiomyocytes was significantly inhibited by SsnB (P < 0.05). Both the mRNA and protein levels of monocyte chemotactic protein-1 and high mobility group box 1 were up-regulated during hypoxia-reoxygenation and were significantly attenuated by SsnB (P < 0.05). Next we found that extracellular signal-regulated kinase 1 or 2 (ERK1/2) and c-Jun NH2-terminal kinase (JNK) signaling pathways were activated during hypoxia-reoxygenation and SsnB significantly inhibited their activation (P < 0.05). Moreover, transwell migration assays revealed that the migration of mouse macrophages to hypoxia-reoxygenation injured cardiomyocytes was significantly reduced by SsnB (P < 0.05). In conclusion, our data indicate that the new selective TLR2 and TLR4 antagonist, SsnB, can substantially attenuate hypoxia-reoxygenation-induced inflammation of cardiomyocytes via inhibiting ERK1/2 and JNK signaling pathways. Accordingly, SsnB has the potential to serve as a therapeutic agent for the prevention of MIR injury.
Assuntos
Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Receptor 2 Toll-Like/antagonistas & inibidores , Receptor 4 Toll-Like/antagonistas & inibidores , Animais , Hipóxia Celular/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Ativação Enzimática , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Inflamação/tratamento farmacológico , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Sistema de Sinalização das MAP Quinases , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/imunologia , Miócitos Cardíacos/metabolismo , RNA Mensageiro/biossíntese , RatosRESUMO
Madecassoside (MA) is a major triterpenoid component of Centella asiatica that has a wide range of biological activities, including wound-healing and antioxidative activities. In the present study, we evaluated the therapeutic effect of MA on rat cardiac dysfunction during sepsis induced by lipopolysaccharide (LPS), as well as the possible mechanism. Pretreatment of the neonatal rat cardiomyocytes with MA inhibited LPS-induced TNF-alpha production in a concentration-dependent manner. In addition, pretreatment of the rats with MA (20 mg/kg, i.g.) significantly inhibited the elevation of plasma TNF-alpha, delayed the fall of mean arterial blood pressure, and attenuated the tachycardia induced by LPS. We further observed that MA prevented the LPS-induced nuclear factor-kappa B (NF-kappaB) translocation from the cytoplasm into the nucleus, and inhibited the LPS-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38. These results suggest that MA inhibits LPS-stimulated TNF-alpha production through the blocking of ERK1/2, p38 and NF-kappaB pathways in cardiomyocytes. MA may have cardioprotective effects in LPS-mediated sepsis.
Assuntos
Miócitos Cardíacos/efeitos dos fármacos , NF-kappa B/metabolismo , Sepse/tratamento farmacológico , Triterpenos/farmacologia , Fator de Necrose Tumoral alfa/biossíntese , Animais , Animais Recém-Nascidos , Células Cultivadas , Centella , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Terapia de Imunossupressão , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/metabolismo , Miócitos Cardíacos/imunologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , NF-kappa B/genética , Ratos , Ratos Sprague-Dawley , Sepse/imunologia , Sepse/patologia , Ativação Transcricional/efeitos dos fármacos , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Experimental autoimmune myocarditis (EAM) in rats is a T-cell-mediated disorder and has been shown to involve immune imbalance. The aim of this study was to examine the immunomodulatory effects of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor, atorvastatin, on the expression of MHC class II molecules in the myocardium of rats with EAM, and to examine its therapeutic potential for EAM. EAM was induced in Lewis rats by injection of porcine cardiac myosin. High-dosage (10 mg/kg per day) or low-dosage (1 mg/kg per day) atorvastatin or vehicle was given orally for 3 weeks. On day 21 after immunization, echocardiography was carried out and the severity of myocarditis was evaluated by histopathological investigations. Immunohistochemistry techniques were used to examine the expression of MHC class II molecules in the myocardium. Type I, III and IV class II transactivator (CIITA) promoter transcription was evaluated by reverse transcription-PCR. Cardiomyocytes were isolated and the expression of MHC class II molecules by them was detected using cytometry. Serum Th1/Th2 cytokines were examined on day 21 by ELISA. Cardiac function was improved in the two atorvastatin-treated groups compared with the untreated one. In atorvastatin groups, the histopathological severity of myocarditis was attenuated and the expression of MHC class II molecules on the 'nonprofessional' APC, the cardiomyocytes, was reduced. mRNA level of type IV CIITA promoter was downregulated in the statin-treated groups in a dosage-dependent manner, but levels of type I and III CIITA mRNA did not differ between the groups statistically. Levels of IFN-gamma and IL-2 increased, whereas levels of IL-4 and IL-10 decreased, in immunized rats from day three through day 21. Atorvastatin reversed these trends in the treated groups. Atorvastatin improves cardiac function and histopathology of the myocardium in EAM by inducing Th2-biased immune responses, and thus 3-hydroxy-3-methyl-glutaryl coenzyme A reductase blockade may be a promising new strategy for the treatment of cardiac autoimmune impairments. The underlying mechanisms may be related to downregulation of MHC class II Ag expression due to silencing of the CIITA mRNA transcription.
Assuntos
Doenças Autoimunes/tratamento farmacológico , Ácidos Heptanoicos/uso terapêutico , Antígenos de Histocompatibilidade Classe II/imunologia , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Miocardite/tratamento farmacológico , Miocárdio/imunologia , Pirróis/uso terapêutico , Linfócitos T/imunologia , Transferência Adotiva , Animais , Atorvastatina , Doenças Autoimunes/imunologia , Modelos Animais de Doenças , Ecocardiografia , Ensaio de Imunoadsorção Enzimática , Genes MHC da Classe II/efeitos dos fármacos , Genes MHC da Classe II/fisiologia , Masculino , Miocardite/imunologia , Miócitos Cardíacos/imunologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos Lew , Células Th2/citologia , Células Th2/efeitos dos fármacos , Células Th2/imunologia , Transativadores/genética , Transativadores/metabolismoRESUMO
We recently reported that mice deficient in the programmed cell death-1 (PD-1) immunoinhibitory coreceptor develop autoimmune dilated cardiomyopathy (DCM), with production of high-titer autoantibodies against a heart-specific, 30-kDa protein. In this study, we purified the 30-kDa protein from heart extract and identified it as cardiac troponin I (cTnI), encoded by a gene in which mutations can cause familial hypertrophic cardiomyopathy (HCM). Administration of monoclonal antibodies to cTnI induced dilatation and dysfunction of hearts in wild-type mice. Monoclonal antibodies to cTnI stained the surface of cardiomyocytes and augmented the voltage-dependent L-type Ca2+ current of normal cardiomyocytes. These findings suggest that antibodies to cTnI induce heart dysfunction and dilatation by chronic stimulation of Ca2+ influx in cardiomyocytes.