RESUMEN
l-Carnitine (LC) exerts beneficial effects in arterial hypertension due, in part, to its antioxidant capacity. We investigated the signalling pathways involved in the effect of LC on angiotensin II (Ang II)-induced NADPH oxidase activation in NRK-52E cells. Ang II increased the generation of superoxide anion from NADPH oxidase, as well as the amount of hydrogen peroxide and nitrotyrosine. Co-incubation with LC managed to prevent these alterations and also reverted the changes in NADPH oxidase expression triggered by Ang II. Cell signalling studies evidenced that LC did not modify Ang II-induced phosphorylation of Akt, p38 MAPK or ERK1/2. On the other hand, a significant decrease in PKC activity, and inhibition of nuclear factor kappa B (NF-kB) translocation, were attributable to LC incubation. In conclusion, LC counteracts the pro-oxidative response to Ang II by modulating NADPH oxidase enzyme via reducing the activity of PKC and the translocation of NF-kB to the nucleus.
Asunto(s)
Angiotensina II/metabolismo , Carnitina/química , Hipertensión/tratamiento farmacológico , NADPH Oxidasas/metabolismo , FN-kappa B/metabolismo , Proteína Quinasa C/metabolismo , Animales , Estrés OxidativoRESUMEN
Leptin is a protein involved in the regulation of food intake and in the immune and inflammatory responses, among other functions. Evidences demonstrate that obesity is directly associated with high levels of leptin, suggesting that leptin may directly link obesity with the elevated cardiovascular and renal risk associated with increased body weight. Adverse effects of leptin include oxidative stress mediated by activation of NADPH oxidase. The aim of this study was to evaluate the effect of L-carnitine (LC) in rat renal epithelial cells (NRK-52E) exposed to leptin in order to generate a state of oxidative stress characteristic of obesity. Leptin increased superoxide anion (O2 (â¢) -) generation from NADPH oxidase (via PI3 K/Akt pathway), NOX2 expression and nitrotyrosine levels. On the other hand, NOX4 expression and hydrogen peroxide (H2 O2 ) levels diminished after leptin treatment. Furthermore, the expression of antioxidant enzymes, catalase, and superoxide dismutase, was altered by leptin, and an increase in the mRNA expression of pro-inflammatory factors was also found in leptin-treated cells. LC restored all changes induced by leptin to those levels found in untreated cells. In conclusion, stimulation of NRK-52E cells with leptin induced a state of oxidative stress and inflammation that could be reversed by preincubation with LC. Interestingly, LC induced an upregulation of NOX4 and restored the release of its product, hydrogen peroxide, which suggests a protective role of NOX4 against leptin-induced renal damage. J. Cell. Biochem. 117: 2281-2288, 2016. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Antioxidantes/farmacología , Carnitina/farmacología , Túbulos Renales Proximales/patología , Leptina/toxicidad , NADPH Oxidasas/metabolismo , Estrés Oxidativo/efectos de los fármacos , Animales , Western Blotting , Células Cultivadas , Activación Enzimática , Humanos , Riñón , Túbulos Renales Proximales/efectos de los fármacos , Túbulos Renales Proximales/metabolismo , NADPH Oxidasas/genética , Sustancias Protectoras/farmacología , ARN Mensajero/genética , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Superóxidos/metabolismoRESUMEN
Sunitinib (Su) is currently approved for treatment of several malignances. However, along with the benefits of disease stabilization, cardiovascular toxicities have also been increasingly recognized. The aim of this study was to analyze which mechanisms are involved in the cardiotoxicity caused by Su, as well as to explore the potential cardioprotective effects of l-carnitine (LC). To this end, four groups of Wistar rats were used: (1) control; (2) rats treated with 400mg LC/kg/day; (3) rats treated with 25mg Su/kg/day; and (4) rats treated with LC+Su simultaneously. In addition, cultured rat cardiomyocytes were treated with an inhibitor of nuclear factor kappa B (NF-κB), in order to examine the role of this transcription factor in this process. An elevation in the myocardial expression of pro-inflammatory cytokines, together with an increase in the mRNA expression of NF-κB, was observed in Su-treated rats. These results were accompanied by an increase in the expression of pro-fibrotic factors, nitrotyrosine and NOX 2 subunit of NADPH oxidase; and by a decrease in that of collagen degradation factor. Higher blood pressure and heart rate levels were also found in Su-treated rats. All these alterations were inhibited by co-administration of LC. Furthermore, cardiotoxic effects of Su were blocked by NF-κB inhibition. Our results suggest that: (i) inflammatory and fibrotic processes are involved in the cardiac toxicity observed following treatment with Su; (ii) these processes might be mediated by the transcription factor NF-κB; (iii) LC exerts a protective effect against arterial hypertension, cardiac inflammation and fibrosis, which are all observed after Su treatment.
Asunto(s)
Antineoplásicos/toxicidad , Cardiotónicos/farmacología , Carnitina/farmacología , Cardiopatías/inducido químicamente , Cardiopatías/prevención & control , Indoles/antagonistas & inhibidores , Indoles/toxicidad , Miocarditis/inducido químicamente , Miocarditis/prevención & control , Pirroles/antagonistas & inhibidores , Pirroles/toxicidad , Animales , Presión Sanguínea/efectos de los fármacos , Cardiotoxicidad , Citocinas/biosíntesis , Fibrosis Endomiocárdica/inducido químicamente , Fibrosis Endomiocárdica/patología , Fibrosis Endomiocárdica/prevención & control , Expresión Génica/efectos de los fármacos , Cardiopatías/patología , Masculino , Miocarditis/patología , Miocitos Cardíacos/efectos de los fármacos , FN-kappa B/metabolismo , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Ratas , Ratas Wistar , SunitinibRESUMEN
BACKGROUND: The development of renal fibrosis is a consequence of arterial hypertension. L-carnitine plays an essential role in the ß-oxidation of fatty acids, and we have previously demonstrated hypotensive, antioxidant, and anti-inflammatory effects of L-carnitine in arterial hypertension. This work aims to analyze the effect of L-carnitine on renal fibrosis and to explore the participation of peroxisome-proliferator activated receptor (PPAR)-γ in this effect. METHODS: Four groups or rats were used: control, treated with L-carnitine, treated with L-NAME, and treated with L-carnitine + L-NAME. Cultured rat kidney cells were also used to examine the role of PPAR-γ in L-carnitine effect. RESULTS: An increase in the expression of collagen, transforming growth factor beta 1 (TGF-ß1), connective tissue growth factor (CTGF), Nox2, and Nox4 was found in the kidney of L-NAME-treated rats. Hypertensive rats presented with an expansion of renal fibrotic areas, which was also accompanied by overexpression of proinflammatory cytokines, interleukin (IL)-1ß, and IL-6. A reduction in the expression of PPAR-γ and in that of anti-inflammatory IL-10 was found in the kidney of these rats. Simultaneous treatment with L-carnitine attenuated the renal fibrosis (which correlated with a reduction of plasma TGF-ß1 levels) and the pro-oxidative and proinflammatory status reported in L-NAME groups, with a concomitant increase in the expression of PPAR-γ. Furthermore, the antifibrotic effect of L-carnitine could be blocked by PPAR-γ inhibition. CONCLUSIONS: This study confirms the efficacy of L-carnitine against hypertension-associated renal fibrosis from in vivo and in vitro studies and suggests that the L-carnitine effect occurs in a PPAR-γ-dependent manner.
Asunto(s)
Carnitina/farmacología , Hipertensión/tratamiento farmacológico , Enfermedades Renales/prevención & control , Túbulos Renales Proximales/efectos de los fármacos , PPAR gamma/efectos de los fármacos , Animales , Células Cultivadas , Colágeno/metabolismo , Factor de Crecimiento del Tejido Conjuntivo/metabolismo , Citoprotección , Modelos Animales de Enfermedad , Inhibidores Enzimáticos , Fibrosis , Hipertensión/inducido químicamente , Hipertensión/metabolismo , Hipertensión/patología , Mediadores de Inflamación/metabolismo , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Enfermedades Renales/etiología , Enfermedades Renales/metabolismo , Enfermedades Renales/patología , Túbulos Renales Proximales/metabolismo , Túbulos Renales Proximales/patología , Masculino , Glicoproteínas de Membrana/metabolismo , NADPH Oxidasa 2 , NADPH Oxidasa 4 , NADPH Oxidasas/metabolismo , NG-Nitroarginina Metil Éster , PPAR gamma/metabolismo , Ratas , Ratas Wistar , Factor de Crecimiento Transformador beta1/metabolismo , Regulación hacia ArribaRESUMEN
Cardiac fibrosis is a pathogenic factor in a variety of cardiovascular diseases and is characterized by an abnormal accumulation of extracellular matrix protein that leads to cardiac dysfunction. l-Carnitine (LC) plays an essential role in the ß-oxidation of long-chain fatty acids in lipid metabolism. We have previously demonstrated the beneficial effects of LC in hypertensive rats. The aim of this study was to analyze the effect of LC on arterial hypertension-associated cardiac fibrosis and to explore the mechanisms of LC action. To this end, four groups of rats were used: Wistar (control), rats treated with 400mg/kg/day of LC, rats treated with 25mg/kg/day of l-NAME (to induce hypertension), and rats treated with LC+l-NAME simultaneously. We found an elevation in the myocardial expression of profibrotic factors (TGF-ß1 and CTGF), types I and III of collagen, and NADPH oxidase subunits (NOX2 and NOX4), in hypertensive rats when compared with normotensive ones. In addition, an increase in myocardial fibrosis was also found in the l-NAME group. These results were accompanied by a down-regulation of PPAR-γ in the heart of hypertensive animals. When hypertensive rats were treated with LC, all these alterations were reversed. Moreover, a significant negative correlation was observed between myocardial interstitial fibrosis and mRNA expression of PPAR-γ. In conclusion, the reduction of cardiac fibrosis and the down-regulation of NOX2, NOX4, TGF-ß1 and CTGF induced by LC might be, at least in part, mediated by an upregulation of PPAR-γ, which leads to a reduction on hypertension-related cardiac fibrosis.