RESUMEN

Advanced oxidation protein products (AOPPs) induce intracellular oxidative stress (OS) and are involved in numerous diseases. AOPPs accumulate with age, and our previous study revealed that AOPPs accelerated bone deterioration in aged rats. However, the underlying mechanism remains unknown. The present study demonstrated that AOPPs aggravated bone loss in aging male mice by increasing the resorptive activity and decreasing the formative activity of bone tissues. In addition, SOST mRNA (encoding sclerostin) and sclerostin protein levels were increased in the bone tissues of AOPP­treated mice, which was associated with enhanced OS status as well as decreased Sirtuin 1 (SIRT1) mRNA and protein expression levels. Incubation of MLO­Y4 cells with AOPPs induced the accumulation of reactive oxygen species (ROS) via the activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. The accumulated ROS then upregulated sclerostin expression in MLO­Y4 cells by decreasing Sirt1 expression. In vivo, AOPP­challenged mice co­treated with apocynin (an inhibitor of NADPH oxidases), N­acetyl­L­cysteine (a ROS scavenger) or SRT3025 (a Sirt1 activator) displayed improved bone mass and microstructure. Moreover, sclerostin expression in the bone tissues of the co­treated groups was significantly lower compared with that in groups treated with AOPPs alone. Collectively, these data suggested that AOPPs aggravated age­related bone loss by increasing the expression of sclerostin in osteocytes via ROS­dependent downregulation of Sirt1. The present findings provide novel insights into the pathogenesis of senile osteoporosis.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/metabolismo , Productos Avanzados de Oxidación de Proteínas/toxicidad , Regulación hacia Abajo , Osteocitos/metabolismo , Osteoporosis/genética , Osteoporosis/patología , Sirtuina 1/genética , Acetofenonas/farmacología , Acetilcisteína/farmacología , Animales , Resorción Ósea/complicaciones , Línea Celular , Regulación hacia Abajo/efectos de los fármacos , Masculino , Ratones Endogámicos C57BL , Osteocitos/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Sirtuina 1/metabolismo

RESUMEN

Intestinal epithelial cell (IEC) cycle arrest has recently been found to be involved in the pathogenesis of Crohn's disease (CD). However, the mechanism underlying the regulation of this form of cell cycle arrest, remains unclear. Here, we investigated the roles that advanced oxidation protein products (AOPPs) may play in regulating IEC cycle arrest. Plasma AOPPs levels and IEC cycle distributions were evaluated in 12 patients with CD. Molecular changes in various cyclins, cyclin-dependent kinases (CDKs), and other regulatory molecules were examined in cultured immortalized rat intestinal epithelial (IEC-6) cells after treatment with AOPPs. The in vivo effects exerted by AOPPs were evaluated using a normal C57BL/6 mouse model with an acute AOPPs challenge. Interestingly, plasma AOPPs levels were elevated in active CD patients and correlated with IEC G1 phase arrest. In addition, IEC treatment with AOPPs markedly reduced the expression of cyclin E and CDK2, thus sensitizing epithelial cells to cell cycle arrest both in vitro and in vivo. Importantly, we found that AOPPs induced IEC G1 phase arrest by modulating two membrane receptors, RAGE and CD36. Furthermore, phosphorylation of c-jun N-terminal kinase (JNK) and the expression of p27kip1 in AOPPs-treated cells were subsequently increased and thus affected cell cycle progression. Our findings reveal that AOPPs influence IEC cycle progression by reducing cyclin E and CDK2 expression through RAGE/CD36-depedent JNK/p27kip1 signaling. Consequently, AOPPs may represent a potential therapeutic molecule. Targeting AOPPs may offer a novel approach to managing CD.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Antígenos CD36/metabolismo , Puntos de Control del Ciclo Celular , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Enterocitos/metabolismo , Fase G1 , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Adulto , Productos Avanzados de Oxidación de Proteínas/sangre , Animales , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular , Enfermedad de Crohn/sangre , Enfermedad de Crohn/patología , Enterocitos/efectos de los fármacos , Enterocitos/patología , Activación Enzimática/efectos de los fármacos , Femenino , Fase G1/efectos de los fármacos , Humanos , Masculino , Ratones Endogámicos C57BL , Transducción de Señal/efectos de los fármacos

RESUMEN

There remains a lack of robust mouse models with key features of advanced human diabetic nephropathy (DN). Few options of murine models of DN require mutations to be superimposed to obtain desired phenotypic characteristics. Most genetically modified mice are on the C57BL/6 background; however, they are notorious for resistance to develop DN. To overcome these conundrums, this study reports a novel DN model by challenging with advanced oxidation protein products (AOPPs) in streptozotocin-induced diabetic C57BL/6 mice. AOPPs-challenged diabetic C57BL/6 mice were more sensitive to develop progressive proteinuria, causing a 5.59-fold increase in urine albumin to creatinine ratio as compared to diabetic controls by 24 weeks. Typical lesions were present as demonstrated by significant diffuse mesangial expansion, diffuse podocyte foot process effacement, increased glomerular basement membrane thickness, focal arteriolar hyalinosis, mesangiolysis, and mild interstitial fibrosis. These changes were alleviated by losartan treatment. Collectively, these results suggest that AOPPs can accelerate the progression of DN in the resistant C57BL/6 mouse strain. Our studies offer a novel model for studying the pathogenesis of DN that resembles human diabetic kidney disease. It also makes it possible to interrogate the role of specific genetic modifications and to evaluate novel therapeutics to treat DN in preclinical setting.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Diabetes Mellitus Experimental , Nefropatías Diabéticas , Animales , Diabetes Mellitus Tipo 2 , Nefropatías Diabéticas/patología , Femenino , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL

RESUMEN

Advanced oxidation protein products (AOPPs) are recognized as novel markers of oxidative stress and contribute to various medical conditions, which are associated with secondary osteoporosis. However, little is currently known regarding the role of AOPPs in the development of secondary osteoporosis. As the commander cells of bone remodeling, osteocytes are involved in the pathogenesis of osteoporosis. The present study aimed to determine the cytotoxic mechanisms of AOPPs on osteocytic MLO­Y4 cells. The results demonstrated that treatment with AOPPs significantly triggered apoptosis of MLO­Y4 cells, in a dose­ and time­dependent manner. Furthermore, exposure to AOPPs induced phosphorylation of c­Jun N­terminal kinases (JNK) and p38 mitogen­activated protein kinases (MAPK). Conversely, N­acetylcysteine inhibited the activation of JNK and p38 MAPK, thus suggesting that the AOPPs­induced activation of JNK/p38 MAPK is reactive oxygen species (ROS)­dependent. In addition, SB203580 and SP600125 suppressed apoptosis, but did not affect ROS production, following AOPPs treatment. Notably, AOPPs also induced a significant upregulation in the expression levels of sclerostin and receptor activator of nuclear factor kappa­B ligand (RANKL) in a JNK/p38 MAPK-dependent manner. These findings provide novel insights into the molecular mechanisms underlying AOPPs­mediated cell death, and suggest that modulation of apoptotic pathways via the MAPK signaling cascade may be considered a therapeutic strategy for the prevention and treatment of secondary osteoporosis.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Apoptosis/efectos de los fármacos , Glicoproteínas/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Ligando RANK/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Acetilcisteína/farmacología , Proteínas Adaptadoras Transductoras de Señales , Animales , Antracenos/farmacología , Línea Celular , Glicoproteínas/genética , Imidazoles/farmacología , Péptidos y Proteínas de Señalización Intercelular , Proteínas Quinasas JNK Activadas por Mitógenos/antagonistas & inhibidores , Ratones , NADPH Oxidasas/antagonistas & inhibidores , NADPH Oxidasas/metabolismo , Piridinas/farmacología , Ligando RANK/genética , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores

RESUMEN

Advanced oxidation protein products (AOPPs) are knownt to play a role in the pathogenesis of diseases and related complications. However, whether AOPPs affect the survival of islet microvascular endothelial cells (IMECs) has not been reported to date, at least to the best of our knowledge. In this study, we aimed to investigate the mechanisms underlying AOPP-mediated damage in IMECs and the protective role of glucagon-like peptide-1 (GLP-1), which has been suggested to exert beneficial effects on the cardiovascular system. IMECs were treated with AOPPs (0-200 µg/ml) for 0-72 h in the presence or absence of GLP-1 (100 nmol/l). Apoptosis, cell viability and reactive oxygen species (ROS) production were examined, the expression levels of p53, Bax, receptor for advanced glycation end-products (RAGE) and NAD(P)H oxidase subunit were determined, and the activity of NAD(P)H oxidase, caspase-9 and caspase-3 was also determined. The results revealed that AOPPs increased the expression of RAGE, p47phox and p22phox; induced NAD(P)H oxidase-dependent ROS generation, increased p53 and Bax expression, enhanced the activity of caspase-9 and caspase-3, and induced cell apoptosis. Treatment with GLP-1 decreased the expression of RAGE, inhibited NAD(P)H oxidase activity, decreased cell apoptosis and increased cell viability. On the whole, our findings indicate that AOPPs induce the apoptosis of IMECs via the RAGE-NAD(P)H oxidase-dependent pathway and that treatment with GLP-1 effectively reverses these detrimental effects by decreasing AOPP-induced RAGE expression and restoring the redox balance. Our data may indicate that GLP-1 may prove to be beneficial in attenuating the progression of diabetes mellitus.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Células Endoteliales/patología , Péptido 1 Similar al Glucagón/farmacología , Islotes Pancreáticos/irrigación sanguínea , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Transducción de Señal/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Caspasa 3/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , NADPH Oxidasas/metabolismo , Sustancias Protectoras/farmacología , Subunidades de Proteína/metabolismo , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Proteína X Asociada a bcl-2/metabolismo

RESUMEN

Inflammation is a relevant factor in the pathogenesis of diabetes nephropathy (DN). Sesquiterpene lactones (SLs), originally isolated from Tanacetum parthenium, have been reported to exhibit anti-inflammatory effects but few studies have examined their effects on DN. To determine whether advanced oxidation protein products (AOPPs) can induce the expression of chemokine monocyte chemoattractant protein- (MCP-) 1 in cultured mouse podocytes and to explore the mechanisms of the potential renoprotection of SLs, we treated podocytes with AOPPs and SLs (parthenolide and its derivatives micheliolide, compound 1, and compound 2). MCP-1 mRNA and protein expression were tested using quantitative real-time PCR and ELISA, respectively, and the protein levels of IKKß, phospho-IKKß, IκBα, NF-κB p65, phospho-NF-κB p65, and tubulin were analyzed by Western blotting. AOPPs activated the expression of MCP-1 mRNA and protein in a dose- and time-dependent manner, activated IKKß and NF-κB p65, and promoted IκBα degradation. The IKK/NF-κB inhibitor parthenolide decreased AOPP-induced MCP-1 expression. Pretreatment with SLs inhibited MCP-1 mRNA and protein expression and suppressed IKKß and NF-κB p65 phosphorylation and IκBα degradation. Taken together, these findings provide a novel explanation for the anti-inflammatory effects of SLs that will ultimately benefit DN and potentially other inflammatory and immune renal diseases.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Quimiocina CCL2/metabolismo , Lactonas/farmacología , Transducción de Señal/efectos de los fármacos , Animales , Línea Celular , Quimiocina CCL2/genética , Regulación de la Expresión Génica/efectos de los fármacos , Proteínas I-kappa B/metabolismo , Ratones , Inhibidor NF-kappaB alfa , FN-kappa B/metabolismo , Fosforilación/efectos de los fármacos , Podocitos/citología , Podocitos/efectos de los fármacos , Podocitos/metabolismo , ARN Mensajero/metabolismo , Sesquiterpenos/química

RESUMEN

Advanced oxidation protein products (AOPPs) are novel markers of oxidation-mediated protein damage, and accumulation of AOPPs is involved in many pathophysiological conditions. Our previous studies demonstrated that the serum level of AOPPs negatively correlated with the age-related change in bone mineral density (BMD) in rats and that AOPPs inhibited rat osteoblast-like cell proliferation and differentiation in vitro. However, whether AOPPs are involved in senile osteoporosis is still largely unknown. The present study aimed to test the hypothesis that accumulation of AOPPs might accelerate bone deterioration in aged rats. Seventy 18-month-old male Sprague Dawley (SD) rats were randomized to intravenous injection of vehicle, native rat serum albumin (RSA), AOPPs-modified RSA (AOPPs-RSA) with or without oral administration of apocynin (a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor), or apocynin alone. After treatment for 8 weeks or 16 weeks, seven rats in each group were sacrificed. Bone and blood samples were harvested for BMD measurement, micro-computed tomographic (micro-CT) imaging, and biochemical analysis of circulating bone biomarkers. Compared to RSA- or vehicle-treated rats, AOPPs-RSA-treated animals displayed significantly decreased total vertebral BMD and deteriorated microstructure in both the tibias and the lumbar vertebral bodies, which were associated with down-regulated plasma bone-specific alkaline phosphatase concentration and up-regulated tartrate-resistant acid phosphatase 5b concentration. These AOPPs-induced perturbations in aged rats could be prevented by the oral administration of apocynin. However, no significant differences in BMD were detected in the femurs or the biomechanical parameters tested between the different treatment groups. These data suggest that accumulation of AOPPs accelerates bone deterioration in aged rats, likely via the activation of NADPH oxidase. This study provides new information toward understanding the pathogenic basis of senile osteoporosis and may provide targets for intervention.

Asunto(s)

Productos Avanzados de Oxidación de Proteínas/toxicidad , Osteoporosis/inducido químicamente , Acetofenonas/farmacología , Productos Avanzados de Oxidación de Proteínas/antagonistas & inhibidores , Productos Avanzados de Oxidación de Proteínas/sangre , Envejecimiento/fisiología , Animales , Antioxidantes/farmacología , Biomarcadores/sangre , Fenómenos Biomecánicos/efectos de los fármacos , Densidad Ósea/efectos de los fármacos , Densidad Ósea/fisiología , Remodelación Ósea/efectos de los fármacos , Remodelación Ósea/fisiología , Inhibidores Enzimáticos/farmacología , Fémur/efectos de los fármacos , Fémur/fisiopatología , Vértebras Lumbares/efectos de los fármacos , Vértebras Lumbares/patología , Vértebras Lumbares/fisiopatología , Masculino , NADPH Oxidasas/antagonistas & inhibidores , Osteoporosis/sangre , Osteoporosis/fisiopatología , Estrés Oxidativo/fisiología , Ratas , Ratas Sprague-Dawley , Tibia/efectos de los fármacos , Tibia/patología , Tibia/fisiopatología

RESUMEN

Advanced oxidation protein products (AOPPs) are formed during chronic oxidative stress as a result of reactions between plasma proteins and chlorinated oxidants. Their levels are elevated during various cardiovascular diseases. Because elevated AOPPs serve as independent risk factors for ischemic heart disease, and cardiomyocyte death is a hallmark of ischemic heart disease, we hypothesized that AOPPs will induce cardiomyocyte death. AOPP-modified mouse serum albumin (AOPP-MSA) induced significant death of neonatal mouse cardiomyocytes that was attenuated by knockdown of the receptor for advanced glycation end products, but not CD36. Notably, TRAF3-interacting protein 2 (TRAF3IP2; also known as CIKS or Act1) knockdown blunted AOPP-induced apoptosis. AOPP-MSA stimulated Nox2/Rac1-dependent superoxide generation, TRAF3IP2 expression, and TRAF3IP2-dependent JNK activation. The superoxide anion generating xanthine/xanthine oxidase system and hydrogen peroxide both induced TRAF3IP2 expression. Further, AOPP-MSA induced mitochondrial Bax translocation and release of cytochrome c into cytoplasm. Moreover, AOPP-MSA suppressed antiapoptotic Bcl-2 and Bcl-xL expression. These effects were reversed by TRAF3IP2 knockdown or forced expression of mutant JNK. Similar to its effects in neonatal cardiomyocytes, AOPP-MSA induced adult cardiomyocyte death in part via TRAF3IP2. These results demonstrate for the first time that AOPPs induce cardiomyocyte death via Nox2/Rac1/superoxide-dependent TRAF3IP2/JNK activation in vitro and suggest that AOPPs may contribute to myocardial injury in vivo. Thus TRAF3IP2 may represent a potential therapeutic target in ischemic heart disease.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/metabolismo , Productos Avanzados de Oxidación de Proteínas/toxicidad , Glicoproteínas de Membrana/metabolismo , Miocitos Cardíacos/metabolismo , NADPH Oxidasas/metabolismo , Neuropéptidos/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Productos Avanzados de Oxidación de Proteínas/química , Productos Avanzados de Oxidación de Proteínas/metabolismo , Animales , Proteínas Sanguíneas/química , Proteínas Sanguíneas/metabolismo , Muerte Celular/efectos de los fármacos , Halogenación , MAP Quinasa Quinasa 4/metabolismo , Ratones , Miocitos Cardíacos/química , NADPH Oxidasa 2 , Oxidantes/química , Oxidantes/metabolismo , Oxidación-Reducción , Estrés Oxidativo , Transducción de Señal , Superóxidos/metabolismo , Superóxidos/toxicidad