Kwang Woo Hwang

Protective effect of caffeic acid against beta-amyloid-induced neurotoxicity by the inhibition of calcium influx and tau phosphorylation

AIMS The progressive accumulation of beta-amyloid peptide (Abeta), in the form of senile plaques, has been recognized as one of the major causes of Alzheimers disease (AD) pathology. Increased production of Abeta and the aggregation of Abeta to oligomers have been reported to trigger neurotoxicity, oxidative damage and inflammation. Furthermore, Abeta-induced tau hyperphosphorylation and neurotoxicity are downstream of Abeta. Therefore, we studied the possible neuroprotective effects of caffeic acid against Abeta-induced toxicity. MAIN METHODS Treatment of PC12 cells with 10 microM Abeta (25-35) for 24 h significantly decreased the cell viability; this was accompanied by an increase in intracellular calcium levels and tau phosphorylation with GSK-3beta (glycogen synthase kinase-3beta) activation (phosphorylation). KEY FINDINGS However, pretreatment of the PC12 cells with 10 and 20 microg/ml of caffeic acid, for 1 h prior to Abeta, significantly reversed the Abeta-induced neurotoxicity by attenuating the elevation of intracellular calcium levels and tau phosphorylation. SIGNIFICANCE Taken together, these results suggest that caffeic acid protected the PC12 cells against Abeta-induced toxicity. In addition, the neuroprotective mechanisms of caffeic acid against Abeta attenuated intracellular calcium influx and decreased tau phosphorylation by the reduction of GSK-3beta activation.

Oral administration of Lactobacillus strains from Kimchi inhibits atopic dermatitis in NC / Nga mice

Aims:  Atopic dermatitis (AD) is marked by elevated levels of immunoglobulin E and skin lesions such as oedema and haemorrhage. Kimchi is a Korean fermented food that contains beneficial bacteria for human health. In this study, Lactobacillus plantarum CJLP55, CJLP56, CJLP133 and CJLP136 isolated from Kimchi were investigated for their capacity to inhibit AD.

2,3,7,8-TCDD neurotoxicity in neuroblastoma cells is caused by increased oxidative stress, intracellular calcium levels, and tau phosphorylation

One of the most notorious environmental toxicants, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), easily accumulates in the environment and most organisms, including humans, because of its high lipophilicity and resistance to degradation. TCDD exposure causes a variety of adverse health effects in humans including immunotoxicity, hepatotoxicity, neurotoxicity, and carcinogenesis. For the most part, studies regarding the adverse effects of TCDD on the central nervous system (CNS) have been limited to neurodevelopmental processes. In this study, we investigated the neurotoxicity of TCDD in neuronal cells using a neuroblastoma cell line (clone N2a) and explored the possible mechanisms of action. MTT and Comet assays were conducted to determine if TCDD is cytotoxic and if it causes DNA damage, respectively. The results of these assays revealed that treatment with 100, 300, 500 and 1000 nM TCDD decreased the viability of N2a cells and increased DNA damage in a dose-dependent manner compared to controls. Additionally, a malondialdehyde (MDA) assay was performed to determine if TCDD induces lipid peroxidation. The results of this assay revealed that 100, 300 and 500 nM TCDD induced lipid peroxidation in a dose-dependent manner. Finally, TCDD neurotoxicity (300 nM or higher) in N2a cells was accompanied by elevated intracellular calcium levels. These increased calcium levels increased the phosphorylation of tau via up-regulation of phospho-glycogen synthase kinase-3beta (GSK-3beta). Taken together, these results indicate that TCDD exposure induces neurotoxicity in N2a cells by increasing DNA damage, oxidative stress and intracellular calcium levels. The TCDD-mediated increase of tau phosphorylation in particular indicates an important role for tau hyperphosphorylation in TCDD-induced neurotoxicity.

Formaldehyde exposure induces airway inflammation by increasing eosinophil infiltrations through the regulation of reactive oxygen species production

Formaldehyde (FA) is a well-known cytotoxic irritant to the airways, but the mechanism of airway inflammation due to FA has not been clarified. In the present study, C57BL/6 mice were exposed to two concentrations (5 and 10ppm) of FA for 6h/day, 5days/week, for 2 weeks. The FA-exposed mice had much higher number of CCR3(+) eosinophils than control mice, and showed upregulated gene expression of CC-chemokine receptor-3 (CCR3), eotaxin and intercellular adhesion molecules-1 (ICAM-1) as well as an increased expression of proinflammatory and Th2 cytokines, such as interleukin (IL)-1β, IL-4 and IL-5. In addition, FA exposure revealed a considerable increase in the serum levels of IgG1, IgG3, IgA and IgE compared to controls. Histopathological analysis of the lung tissues demonstrated eosinophils and mononuclear cell infiltration of the alveolar cell walls and alveolar spaces. Gene expression of thioredoxin (TRX), redox-regulating antioxidant proteins, was markedly suppressed in FA-exposed mice, and thereby intracellular ROS levels were increased along with increased FA concentration. These results were consistent with an increase in the number of CCR3-expressing eosinophils, and indicate that FA-induced ROS was generated from eosinophils recruited to the inflammatory sites of the airways.

Modulation of Th1/Th2 balance by Lactobacillus strains isolated from Kimchi via stimulation of macrophage cell line J774A.1 in vitro.

UNLABELLED Lactobacilli isolated from Kimchi, a Korean traditional food, were tested for their capacity to modulate the T helper (Th) 1/Th2 balance. Ovalbumin (OVA)-sensitized mouse splenocytes were cultured with 26 strains of lactobacilli; the highest IL-12 induction and lowest IL-4 production were then observed in 4 strains, including Lactobacillus plantarum CJLP55, CJLP56, CJLP133, and CJLP136. These strains produced a larger amount of IL-12, which enhances differentiation and activation of Th1 cells, in macrophage cell-lines more than positive control strains L. casei KCTC 3109(T) and L. rhamnosus GG, although they also induced production of IL-10, which is a suppressor of IL-12. Indeed, CJLP133-stimulated macrophages induced production of more Th1 cytokine IFN-γ and less Th2 cytokine IL-4 than KCTC 3109(T) and GG in co-cultivation with T cells. These findings suggest that lactobacilli from Kimchi may modulate the Th1/Th2 balance via macrophage activation in the hypersensitive reaction caused by Th2 cells. PRACTICAL APPLICATION Allergic reactions including asthma and atopy are caused by predominance of Th2 response over Th1 response. Lactobacilli isolated from fermented foods such as yogurt, cheese, and Kimchi showed health-promoting activities. The present study indicated that several lactobacilli strains from Kimchi may reduce allergic reactions through macrophage-mediated induction of Th1 response.

Age-Associated Changes in MicroRNA Expression in Bone Marrow Derived Dendritic Cells

MiRNAs have shown to regulate aging process at the level of cellular senescence, tissue aging, and lifespan of whole organism. Given that many miRNAs also function as important regulators of hematopoietic system as well as aging process, it is highly likely that miRNAs would be involved in the changes of myeloid function and differentiation during aging. Therefore, here we examine differential expression of miRNAs in aged myeloid lineage cells and assess if altered miRNA expression pattern would reflect the change of miRNA targets and related function. We demonstrated that the expressions of myelogenic miRNAs such as miR-155, miR-223, miR-146a, miR-146b, miR-132, miR-142-5p, and miR-142-3p were increased in aged bone marrow derived dendritic cells (BMDC) under normal and activated conditions. We also observed that the expressions of IRAK1 and TRAF6, the targets of miR-146a, and DC-SIGN, a target of miR-155 were diminished while miR-146a and miR-155 were augmented during aging. In addition, we found that the production of pro-inflammatory cytokines, which is mediated by the activation of NF-kB pathway via IRAK1 and TRAF6, was greatly reduced in aged BMDC. Taken together, our data reveal that age-associated changes occur in miRNA expression in BMDC, and this altered miRNA expression affects miRNA target expression and compromises BMDC function such as cytokine production during aging.

The new diterpene isodojaponin D inhibited LPS-induced microglial activation through NF-kappaB and MAPK signaling pathways.

Neuroinflammation with prolonged microglial activation leads to increased levels of pro-inflammatory mediators and subsequently contributes to neuronal dysfunction and neuronal loss. Therefore, pharmacological suppression of neuroinflammation would theoretically slow the progression of neurodegenerative disease. In this study, we investigated the anti-inflammatory effects and possible mechanisms of isodojaponin D (19-hydroxy-1alpha,6-diacetoxy-6,7-seco-ent-kaur-16-en-15-one-7,20-olide), a new diterpene isolated from Isodon japonicus against lipopolysaccharide(LPS)-induced microglial activation in BV2 cells. Results from RT-PCR and Western blot showed that pretreatment with isodojaponin D (5 and 10 microg/ml) prior to treatment with LPS (1 microg/ml) significantly decreased LPS-induced production of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in a dose-dependent manner. In addition, LPS-induced pro-inflammatory cytokines, including IL-1beta, IL-6, and TNF-alpha, were also decreased by pretreatment with isodojaponin D. This effect was accompanied by a decrease in translocations of Nuclear Factor-KappaB (NF-kappaB) p50 and p65 from the cytoplasm to the nucleus and by a decrease in I kappaB (IkappaB) degradation. In addition, pretreatment with isodojaponin D significantly attenuated LPS-induced mitogen-activated protein kinase (MAPK) activation. Taken together, these results suggest that isodojaponin D suppressed LPS-induced microglial activation and production of pro-inflammatory mediators by inhibition of the NF-kappaB signaling pathway and phosphorylation of MAPKs. These results suggest that isodojaponin D could play a beneficial role in treatment of neurodegenerative disease.

T Cell Stimulatory Effects of Korean Red Ginseng through Modulation of Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSCs) actively suppress immune cells and have been considered as an impediment to successful cancer immunotherapy. Many approaches have been made to overcome such immunosuppressive factors and to exert effective anti-tumor effects, but the possibility of using medicinal plants for this purpose has been overlooked. Korean red ginseng (KRG) is widely known to possess a variety of pharmacological properties, including immunoboosting and anti-tumor activities. However, little has been done to assess the anti-tumor activity of KRG on MDSCs. Therefore, we examined the effects of KRG on MDSCs in tumor-bearing mice and evaluated immunostimulatory and anti-tumor activities of KRG through MDSC modulation. The data show that intraperitoneal administration of KRG compromises MDSC function and induces T cell proliferation and the secretion of IL-2 and IFN-γ, while it does not exhibit direct cytotoxicity on tumor cells and reduced MDSC accumulation. MDSCs isolated from KRG-treated mice also express significantly lower levels of inducible nitric oxide synthase and IL-10 accompanied by a decrease in nitric oxide production compared with control. Taken together, the present study demonstrates that KRG enhances T cell function by inhibiting the immunosuppressive activity of MDSCs and suggests that although KRG alone does not exhibit direct anti-tumor effects, the use of KRG together with conventional chemo- or immunotherapy may provide better outcomes to cancer patients through MDSC modulation.

The mouse small ubiquitin-like modifier-2 (SUMO-2) inhibits interleukin-12 (IL-12) production in mature dendritic cells by blocking the translocation of the p65 subunit of NFκB into the nucleus.

Post-translational modification by small ubiquitin-like modifier (SUMO) is involved in several significant cellular events. In particular, SUMO-1 and SUMO-4 modifications of IκBα have been shown to be actively involved in NFκB regulation. However, among the SUMO family, the specific function of SUMO-2/3 remains relatively unknown. In addition, it is not clear whether SUMO-2/3 follows the same functional role as SUMO-1 and SUMO-4 during the activation of NFκB. In this study, we examined the influence of mouse SUMO-2 during the maturation of dendritic cells (DCs). Our results showed that the ectopic expression of SUMO-2 does not affect the cell surface expression of MHC class II molecule (A(b)) and co-stimulatory molecules (CD80 and CD86), and the efficiency of antigen uptake. However, the ectopic expression of mouse SUMO-2 inhibited IL-12 secretion by blocking the translocation of the p65 subunit of NFκB into the nucleus, which led to the polarization of naïve CD4(+) T cells to T helper 2 (Th2) shift in vitro. Further analyses showed that SUMO-2 directly modified IκBα. These results indicate that the functional role of SUMO-2/3 in the regulation of NFκB activity was conserved during evolution.

In Vitro antioxidative and anti-inflammatory activities of the ethanol extract of eggplant (Solanum melongena) stalks in macrophage RAW 264.7 cells

ABSTRACT Solanum melongena or eggplant is a species of the nightshade family. According to Korean folk medicine, S. melongena stalk possesses excellent therapeutic effects on warts, burns, and many inflammatory diseases, such as stomatitis, arthritis, and gastritis. In order to investigate the anti-inflammatory effects of S. melongena stalk, an ethanol extract of the stalk was prepared, and fractionated into hexane, dichloromethane, ethyl acetate, n-butanol, and water fractions. The results showed that the ethyl acetate and n-butanol fractions contained high levels of phenol and reduced artificial free radicals. In contrast, the hexane and dichloromethane fractions decreased the production of nitric oxide, pro-inflammatory cytokines, and prostaglandin E2, despite the presence of low levels of phenols implying that other compounds than phenols are involved in anti-inflammatory reactions. The data suggest that S. melongena stalk possesses pharmacological activity and might be useful for development of antioxidant, anti-inflammatory agents, or dietary supplements.