Je-Won Ko

Copper oxide nanoparticles aggravate airway inflammation and mucus production in asthmatic mice via MAPK signaling.

Abstract Copper oxide nanoparticles (CuONPs), metal oxide nanoparticles were used in multiple applications including wood preservation, antimicrobial textiles, catalysts for carbon monoxide oxidation and heat transfer fluid in machines. We investigated the effects of CuONPs on the respiratory system in Balb/c mice. In addition, to investigate the effects of CuONPs on asthma development, we used a murine model of ovalbumin (OVA)-induced asthma. CuONPs markedly increased airway hyper-responsiveness (AHR), inflammatory cell counts, proinflammatory cytokines and reactive oxygen species (ROS). CuONPs induced airway inflammation and mucus secretion with increases in phosphorylation of the MAPKs (Erk, JNK and p38). In the OVA-induced asthma model, CuONPs aggravated the increased AHR, inflammatory cell count, proinflammatory cytokines, ROS and immunoglobulin E induced by OVA exposure. In addition, CuONPs markedly increased inflammatory cell infiltration into the lung and mucus secretions, and MAPK phosphorylation was elevated compared to OVA-induced asthmatic mice. Taken together, CuONPs exhibited toxicity on the respiratory system, which was associated with the MAPK phosphorylation. In addition, CuONPs exposure aggravated the development of asthma. We conclude that CuONPs exposure has a potential toxicity in humans with respiratory disease.

Comparative toxicity and biodistribution of copper nanoparticles and cupric ions in rats.

Despite widespread use and prospective biomedical applications of copper nanoparticles (Cu NPs), their biosafety issues and kinetics remain unclear. Thus, the aim of this study was to compare the detailed in vivo toxicity of Cu NPs and cupric ions (CuCl2; Cu ions) after a single oral dose. We determined the physicochemical characteristics of Cu NPs, including morphology, hydrodynamic size, zeta potential, and dissolution in gastric (pH 1.5), vehicle (pH 6.5), and intestinal (pH 7.8) conditions. We also evaluated the kinetics of Cu following a single equivalent dose (500 mg/kg) of Cu NPs and Cu ions. Cu NPs had highest dissolution (84.5%) only in gastric conditions when compared with complete dissolution of Cu ions under various physiological milieus. Kinetic analysis revealed that highest Cu levels in blood and tested organs of Cu NP-treated rats were 15%–25% lower than that of Cu ions. Similar to the case of Cu ions, Cu levels in the tested organs (especially liver, kidney, and spleen) of Cu NP-treated rats increased significantly when compared with the vehicle control. However, delay in reaching the highest level and biopersistence of Cu were observed in the blood and tested organs of Cu NP-treated rats compared with Cu ions. Extremely high levels of Cu in feces indicated that unabsorbed Cu NPs or absorbed Cu ions were predominantly eliminated through liver/feces. Cu NPs exerted apparent toxicological effects at higher dose levels compared with Cu ions and showed sex-dependent differences in mortality, biochemistry, and histopathology. Liver, kidney, and spleen were the major organs affected by Cu NPs. Collectively, the toxicity and kinetics of Cu NPs are most likely influenced by the release of Cu dissociated from Cu NPs under physiological conditions.

Silver nanoparticles induce apoptotic cell death in cultured cerebral cortical neurons

Silver nanoparticles (SNPs) have been widely produced and exploited in diverse products, primarily because of their antimicrobial properties. The present study investigated the induction of apoptotic cell death and oxidative stress in cultured cortical neurons in response to SNP exposure. In order to assess the toxicity of SNPs, the cultured cortical neurons were exposed to 0.4, 2, and 10 μg/mL of SNPs for 6, 12, and 24 h. Lactate dehydrogenase released from damaged cells was quantified and the levels of intracellular reactive oxygen species (ROS) were measured using 2′-7′-dichlorofluorescin diacetate. Apoptosis induced by SNPs was analyzed using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), a DNA ladder assay and Western blot analysis. SNPs inhibited the viability of cerebral cortical neurons in a dose- and time-dependent manner. Levels of ROS increased significantly at 12 and 24 h after treatment. TUNEL showed that compared with controls, numerous apoptotic cells appeared in the treated cultures at 12 and 24 h after treatment. DNA fragmentation in SNP-exposed cells suggested apoptosis. Western blot analysis demonstrated that cleaved caspase-3 protein expression increased significantly in a time-dependent manner. These results suggest that SNPs cause cytotoxicity and neuronal apoptosis through increasing intracellular ROS production in cultured cortical neurons.

Protective effects of diallyl disulfide against acetaminophen-induced nephrotoxicity: A possible role of CYP2E1 and NF-κB.

Diallyl disulfide (DADS) is a degradation product of allicin which is contained in garlic. This study investigated the protective effects of DADS against acetaminophen (AAP)-induced nephrotoxicity and the molecular mechanisms of nephroprotective effects in rats. AAP caused severe nephrotoxicity as evidenced by significant increases in renal tubular cell apoptosis, mitochondria-mediated apoptosis, and up-regulation of nuclear transcription factor kappa-B (NF-κB), cyclooxygenase-2 (Cox-2), and tumor necrosis factor-α (TNF-α) in the kidney with histopathological alterations. After AAP administration, glutathione content and activities of catalase, superoxide dismutase, and glutathione reductase were significantly decreased whereas malondialdehyde content was significantly increased, indicating that AAP-induced kidney injury was mediated through oxidative stress. In contrast, DADS pretreatment significantly attenuated AAP-induced nephrotoxic effects, including oxidative damage, histopathological lesions, and apoptotic changes in the kidney. DADS also attenuated AAP-induced up-regulation of NF-κB, Cox-2, and TNF-α in the kidney, and microsomal CYP2E1 expression in liver and kidney. These results indicated that DADS could prevent AAP-induced nephrotoxicity. The protective effects of DADS might be due to its ability to decrease metabolic activation of AAP by inhibiting CYP2E1 and its potent antioxidant, antiapoptotic, and antiinflammatory effects via inhibition of NF-κB.

Protective effects of pine bark extract against cisplatin-induced hepatotoxicity and oxidative stress in rats.

We investigated the protective effects of pine bark extract (pycnogenol®, PYC) against cisplatin-induced hepatotoxicity and oxidative stress in rats. Twenty-four male rats were divided into the following four groups: (1) vehicle control, (2) cisplatin (7.5 mg/kg), (3) cisplatin & PYC 10 (10 mg/kg/day), and (4) cisplatin & PYC 20 (20 mg/kg/day). A single intraperitoneal injection of cisplatin induced hepatotoxicity, as evidenced by an increase in serum aminotransferase and histopathological alterations, including degeneration/necrosis of hepatocytes, vacuolation, and sinusoidal dilation. In addition, an increase in the malondialdehyde (MDA) concentration and a decrease in the reduced glutathione (GSH) content and catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) activities were observed in the cisplatin-treated rat hepatic tissues. In contrast, PYC treatment effectively prevented cisplatin-induced hepatotoxicity, including the elevation of aminotransferase and histopathological lesions, in a dosedependent manner. Moreover, PYC treatment also induced antioxidant activity by decreasing MDA level and increasing GSH content and SOD and GST activities in liver tissues. These results indicate that PYC has a protective effect against acute hepatotoxicity induced by cisplatin in rats, and that the protective effects of PYC may be due to inhibiting lipid peroxidation and increasing antioxidant activity.

Role of mitogen-activated protein kinases and nuclear factor-kappa B in 1,3-dichloro-2-propanol-induced hepatic injury.

In this study, the potential hepatotoxicity of 1,3-dichloro-2-propanol and its hepatotoxic mechanisms in rats was investigated. The test chemical was administered orally to male rats at 0, 27.5, 55, and 110 mg/kg body weight. 1,3-Dichloro-2-propanol administration caused acute hepatotoxicity, as evidenced by an increase in serum aminotransferases, total cholesterol, and total bilirubin levels and a decrease in serum glucose concentration in a dose-dependent manner with corresponding histopathological changes in the hepatic tissues. The significant increase in malondialdehyde content and the significant decrease in glutathione content and antioxidant enzyme activities indicated that 1,3-dichloro-2-propanol-induced hepatic damage was mediated through oxidative stress, which caused a dose-dependent increase of hepatocellular apoptotic changes in the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and immunohistochemical analysis for caspase-3. The phosphorylation of mitogen-activated protein kinases caused by 1,3-dichloro-2-propanol possibly involved in hepatocellular apoptotic changes in rat liver. Furthermore, 1,3-dichloro-2-propanol induced an inflammatory response through activation of nuclear factor-kappa B signaling that coincided with the induction of pro-inflammatory mediators or cytokines in a dose-dependent manner. Taken together, these results demonstrate that hepatotoxicity may be related to oxidative stress-mediated activation of mitogen-activated protein kinases and nuclear factor-kappa B-mediated inflammatory response.

Time-course and molecular mechanism of hepatotoxicity induced by 1,3-dichloro-2-propanol in rats

This study investigated the time-course of 1,3-dichloro-2-propanol (1,3-DCP)-induced hepatotoxicity and the molecular mechanism of its oxidative stress and apoptotic changes in rats. Thirty-six male rats were randomly assigned to six groups of six rats each and were administered a single oral dose of 1,3-DCP (90 mg/kg) or its vehicle. 1,3-DCP caused acute hepatic damage, as evidenced by marked increases in serum aminotransferase, alkaline phosphatase, and histopathological alterations. These functional and histopathological changes in the liver peaked at 12h after administration and then decreased progressively. Oxidative stress indices were increased significantly at 6h, peaked at 12h, and then decreased progressively. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)- and caspase-3-positive cells increased after 6h, peaked at 12 and 24h, and then decreased. The protein levels of phosphorylated mitogen-activated protein kinases (MAPKs) including p-Erk1/2 and p-JNK showed a similar trend to the numbers of TUNEL- and caspase-3-positive cells. These results indicate that 1,3-DCP increases oxidative stress, nuclear translocation of Nrf2, and expression of Nrf2-targeted genes, followed by increased functional and histopathological alterations in the liver. The increase in hepatocellular apoptosis induced by 1,3-DCP may be related to oxidative stress-mediated MAPK activation.

Protective effects of garlic oil against 1,3-dichloro-2-propanol-induced hepatotoxicity: role of CYP2E1 and MAPKs

Abstract1,3-Dichloro-2-propanol (1,3-DCP) is a well-known food contaminant that can be detected during the production of a wide range of foods. We investigated whether garlic oil (GO) has protective effects against 1,3-DCP-induced hepatotixicy and oxidative damage in rats. GO significantly attenuated the 1,3-DCP-induced increase in serum aminotransferase activities. This effect was accompanied by attenuation of the histopahological alterations in liver caused by 1,3-DCP. In 1,3-DCP-treated rats, GO prevented formation of hepatic malondialdehyde and depletion of reduced glutathione content, and promoted hepatic antioxidant enzymes activities. 1,3-DCP caused apoptosis in the liver with increases phosphorylation of mitogen-activated protein kinases (MAPKs); GO significantly attenuated these alterations and suppressed the expression of hepatic cytochrome P450 2E1 (CYP2E1). These results suggest that the protective effects of GO against 1,3-DCP-induced hepatotoxicity involve the ability to induce antioxidant enzymes, block metabolic activation of 1,3-DCP by suppressing CYP2E1 expression, and induce antiapoptotic activity by inhibiting phosphorylation of MAPKs.

Protective effect and mechanism of action of diallyl disulfide against acetaminophen-induced acute hepatotoxicity

The aim of this study was to investigate the potential protective effects of diallyl disulfide (DADS) against acetaminophen (AAP)-induced acute hepatotoxicity and elucidate the molecular mechanisms underlying these protective effects in rats. Treatment with AAP caused acute hepatotoxicity manifested by elevated levels of aspartate aminotransferase and alanine aminotransferase with corresponding histopathological changes and high levels of oxidative stress in the livers. AAP treatment also caused hepatocellular apoptosis with phosphorylation of c-Jun-N-terminal protein kinase (JNK). In addition, AAP caused activation of nuclear factor kappaB (NF-κB) concurrent with induction of inflammatory mediators. In contrast, pretreatment with DADS effectively attenuated acute liver injury and oxidative stress caused by AAP. DADS pretreatment suppressed cytochrome P450 2E1 (CYP2E1) levels in a dose-dependent manner and inhibited elevation of CYP2E1 activity induced by AAP. DADS pretreatment suppressed the phosphorylation of JNK and attenuated hepatocellular apoptotic changes. In addition, DADS inhibited the nuclear translocation of NF-κB and subsequent induction of inflammatory mediators. Overall, these results indicate that DADS confers a protective effect against oxidative stress-mediated JNK activation and apoptotic changes caused by AAP in the rat livers. This may be due to its ability to inhibit CYP2E1, enhance antioxidant enzymes activities, and suppress NF-κB activation.

Protective effect of HwangRyunHaeDok-Tang water extract against chronic obstructive pulmonary disease induced by cigarette smoke and lipopolysaccharide in a mouse model

ETHNOPHARMACOLOGICAL RELEVANCE Hwangryunhaedok-tang is an oriental herbal formula treated to cure inflammation and gastric disorders in China, Japan, and Korea. We explored the protective effects of Hwangryunhaedok-tang water extract (HRWE) against airway pathophysiological changes caused by cigarette smoke (CS) and lipopolysaccharide (LPS) in a mouse. MATERIALS AND METHODS We performed quantitative analyses of five marker components, namely geniposide, baicalin, coptisine, plamatine, and berberine, using high-performance liquid chromatography. Animals were received CS exposure (1h per day) for 7 days. LPS was administered intranasally on day 4. Mice were received HRWE at dose of 100 or 200mg/kg for 1h before CS exposure. RESULTS Treatment with HRWE significantly suppressed the increased inflammatory cell count induced by CS and LPS exposure. In addition, reduction in IL-6, TNF-α and IL-1β in broncho-alveolar lavage fluid (BALF) was observed after HRWE treatment. HRWE not only decreased inflammatory cell infiltration in lung, but also decreased the expression of iNOS, NF-κB and matrix metallopeptidase (MMP)-9 in lung tissues. CONCLUSION This study showed that HRWE can attenuate respiratory inflammation caused by CS and LPS exposure. Therefore, HRWE has potential for treating airway inflammatory disease.