• IMMUNE NETWORK
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• v.3 no.1
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• pp.29-37
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• 2003

Background: CC chemokine receptor (CCR) 7 and cognate CCR7 ligands, CCL21 (formerly secondary lymphoid tissue chemokine [SLC]) and CCL19 (formerly Epstein-Barr virus-induced molecule 1 ligand chemokine [ELC]), were known to establish microenvironment for the initiation of immune responses in secondary lymphoid tissue. As described previously, coadministration of DNA vaccine with CCR7 ligand-encoding plasmid DNA elicited enhanced humoral and cellular immunity via increasing the number of dendritic cells (DC) in secondary lymphoid tissue. The author hypothesized here that CCR7 ligand DNA could effectively expand memory CD4+ T cells to protect from viral infection likely via increasing DC number. Methods: To evaluate the effect of CCR7 ligand DNA on the expansion of memory CD4+ T cells, DO11.10.BALB/c transgenic (Tg)-mice, which have highly frequent ovalbumin $(OVA)_{323-339}$ peptide-specific CD4+ T cells, were used. Tg-mice were previously injected with CCR7 ligand DNA, then immunized with $OVA_{323-339}$ peptide plus complete Freund's adjuvant. Subsequently, memory CD4+ T cells in peripheral blood lymphocytes (PBL) were analyzed by FACS analysis for memory phenotype ($CD44^{high}$ and CD62 $L^{low}$) at memory stage. Memory CD4+ T cells recruited into inflammatory site induced with OVA-expressing virus were also analyzed. Finally, the protective efficacy against viral infection was evaluated. Results: CCR7 ligand DNA-treated Tg-mice showed more expanded $CD44^{high}$ memory CD4+ T cells in PBL than control vector-treated animals. The increased number of memory CD4+ T cells recruited into inflammatory site was also observed in CCR7 ligand DNA-treated Tg-mice. Such effectively expanded memory CD4+ T cell population increased the protective immunity against virulent viral infection. Conclusion: These results document that CCR7 and its cognate ligands play an important role in intracellular infection through establishing optimal memory T cell. Moreover, CCR7 ligand could be useful as modulator in DNA vaccination against viral infection as well as cancer.

• Toxicological Research
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• v.3 no.2
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• pp.129-141
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• 1987

Hepatocytes isolated from rats which have been pretreated with phenobarbital (80 mg/kg for 3 days), were able to take up N-acetylcysteine from surrounding medium and were able to synthesize the reduced glutathione ($GSH^{\ast}-3$) intracellularly. The N-acetylcysteine is quickly deacetylated after the uptake and increases the pool size of cysteine, which was very low initially (5 nmol/$10^6$ cells). From this increased intracellular cysteine pool, GSH was synthesized. Freshly isolated rat hepatocytes contained a high level of GSH (30 nmol/$10^6$ cells), but upon incubation with the diethylmaleate, it was markedly decreased (10 nmol/$10^6$ cells). The hepatocytes with depleted GSH have lost viability upon incubations with acetaminophen (5mM) and paraquat (2 mM). However, when the N-acetylcysteine (1 mM) was added to this incubation condition, these chemical induced hepatocellular necrosis were prevented for longer durations. This N-acetylcysteine dependent protective effect against the hepatotoxic chemicals was lost by adding methionine sulfoximine (10 mM), an inhibitor of GSH biosynthesis. Both the carbontetrachloride (5 mM) and chioroform (5 mM) added to the incubation medium caused rapid losses of GSH and cell viability, even without the prior depletion of cellular GSH. However, again, if the 1mM N-acetylcysteine was supplemented, the rates of losses of GSH and cell viability were retarded in both cases. Even though large amounts of the added N-acetylcysteine was present in the cell, N-acetylcysteine conjugate of acetaminophen was not formed. Instead, only large amounts of GSH conjugate of the drug was produced. Thus, it is concluded that the added N-acetylcysteine is taken up and utilized for resynthesis of GSH. In turn, this resynthesized GSH contributes to the protection against cytotoxicity inducible with hepatotoxic drugs.

• Journal of Life Science
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• v.20 no.1
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• pp.27-32
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• 2010

Ultraviolet-B (UVB) radiation induces the formation of reactive oxygen species (ROS) and depletes stores of cellular antioxidants. Fucoidan, polysaccharides containing L-fucose and sulfate ester groups, are constituents of brown algae. In this study, the protective effects of fucoidan on UVB-induced oxidative stress in cultured human skin fibroblast HS68 cells were assessed. Pretreatment with fucoidan significantly reduced malondialdehyde (MDA) content in a dose-dependent manner. With fucoidan pretreatment at a dose of $100\;{\mu}g/ml$, the level of intracellular glutathione was increased by 21.5%, compared to UVB irradiation alone. Fucoidan significantly reduced UVB-induced ROS generation by 40.1% and 68.4% at 10 and $100\;{\mu}g/ml$, respectively, compared to UVB irradiation alone. The positive staining rates of senescence-associated $\beta$-galactosidase were reduced by 23.1% and 16.4% with 10 and $100\;{\mu}g/ml$ of fucoidan, compared to UVB irradiation alone. Fucoidan may exert a photoprotective effect against UVB radiation-induced oxidative stress.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.2
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• pp.61-67
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• 2007

In this study, the antioxidative effects of Equisetum arvense extracts were investigated. The free radical (1,1 diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$) of extract/fractions of Equisetum arvense was in the order: 50 % ethanol extract ($182.04{\mu}g/mL$) < ethylacetate fraction ($54.50{\mu}g/mL$) < deglycosylated flavonoid aglycone fraction ($14.13{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of some Equisetum arvense extracts on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol- dependent chemiluminescence assay. The order of ROS scavenging activity was deglycosylated flavonoid aglycone fraction ($OSC_{50}$, $3.54{\mu}g/mL$) < 50 % ethanol extract ($0.80{\mu}g/mL$) < ethylacetate fraction ($0.006{\mu}g/mL$). Ethylacetate fraction showed the most prominent scavenging activity. The protective effects of extract/fractions of Equisetum arvense on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The ethanol extract (50%) suppressed photohemolysis in a concentration dependent manner, particularly deglycosylated aglycone extract exhibited the most prominent celluar protective effect ($\tau_{50}$, 161.10 min at $10{\mu}g/mL$). These results indicate that extract/fractions of Equisetum arvense can function as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.13.1-13.15
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• 2018

Wound healing is delayed in diabetic patients. Increased apoptosis and endothelial progenitor cell (EPC) dysfunction are implicated in delayed diabetic wound healing. Melatonin, a major secretory product of the pineal gland, promotes diabetic wound healing; however, its mechanism of action remains unclear. Here, EPCs were isolated from the bone marrow of mice. Treatment of EPCs with melatonin alleviated advanced glycation end product (AGE)-induced apoptosis and cellular dysfunction. We further examined autophagy flux after melatonin treatment and found increased light chain 3 (LC3) and p62 protein levels in AGE-treated EPCs. However, lysosome-associated membrane protein 2 expression was decreased, indicating that autophagy flux was impaired in EPCs treated with AGEs. We then evaluated autophagy flux after melatonin treatment and found that melatonin increased the LC3 levels, but attenuated the accumulation of p62, suggesting a stimulatory effect of melatonin on autophagy flux. Blockage of autophagy flux by chloroquine partially abolished the protective effects of melatonin, indicating that autophagy flux is involved in the protective effects of melatonin. Furthermore, we found that the AMPK/mTOR signaling pathway is involved in autophagy flux stimulation by melatonin. An in vivo study also illustrated that melatonin treatment ameliorated impaired wound healing in a streptozotocin-induced diabetic wound healing model. Thus, our study shows that melatonin protects EPCs against apoptosis and dysfunction via autophagy flux stimulation and ameliorates impaired wound healing in vivo, providing insight into its mechanism of action in diabetic wound healing.

• Preventive Nutrition and Food Science
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• v.21 no.1
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• pp.14-23
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• 2016

Non-alcoholic fatty liver disease (NAFLD) is caused by fat accumulation and is associated with oxidative stress. In this study, we investigated the potential protective effect of pomegranate (Punica granatum L.) peel extract (PPE) against oxidative stress in the liver of rats with NAFLD. Sprague-Dawley rats were fed a high fat diet (HFD), 20% corn oil, or palm oil for 8 weeks in the presence or absence of PPE. The control group was fed a basal diet. The progression of NAFLD was evaluated histologically and by measuring liver enzymes (alanine transaminase and aspartate transaminase), serum lipids (triglycerides and total cholesterol), and oxidative stress markers. The HFD feeding increased the body weight and caused NAFLD, liver steatosis, hyperlipidemia, oxidative stress, and elevated liver enzymes. Administration of PPE ameliorated the hepatic morphology, reduced body weight, improved liver enzymes, and inhibited lipogenesis. Furthermore, PPE enhanced the cellular redox status in the liver tissue of rats with NAFLD. Our findings suggest that PPE could improve HFD-induced NAFLD via abolishment of hepatic oxidative damage and hyperlipidemia. PPE might be considered as a potential lead material in the treatment of NAFLD and obesity through the modulation of lipid metabolism.

• Molecules and Cells
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• v.43 no.11
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• pp.964-973
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• 2020

Recent studies have highlighted that early enhancement of the glycolytic pathway is a mode of maintaining the proinflammatory status of immune cells. Thiamine, a wellknown co-activator of pyruvate dehydrogenase complex, a gatekeeping enzyme, shifts energy utilization of glucose from glycolysis to oxidative phosphorylation. Thus, we hypothesized that thiamine may modulate inflammation by alleviating metabolic shifts during immune cell activation. First, using allithiamine, which showed the most potent anti-inflammatory capacity among thiamine derivatives, we confirmed the inhibitory effects of allithiamine on the lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production and maturation process in dendritic cells. We applied the LPS-induced sepsis model to examine whether allithiamine has a protective role in hyper-inflammatory status. We observed that allithiamine attenuated tissue damage and organ dysfunction during endotoxemia, even when the treatment was given after the early cytokine release. We assessed the changes in glucose metabolites during LPS-induced dendritic cell activation and found that allithiamine significantly inhibited glucose-driven citrate accumulation. We then examined the clinical implication of regulating metabolites during sepsis by performing a tail bleeding assay upon allithiamine treatment, which expands its capacity to hamper the coagulation process. Finally, we confirmed that the role of allithiamine in metabolic regulation is critical in exerting anti-inflammatory action by demonstrating its inhibitory effect upon mitochondrial citrate transporter activity. In conclusion, thiamine could be used as an alternative approach for controlling the immune response in patients with sepsis.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.675-687
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• 2000

Multiple periodontal pathogens sequentially colonize the subgingival niche during the conversion from gingivitis to destructive periodontal disease. An animal model of sequential immunization with key periodontal pathogens has been developed to determine whether T and B lymppocyte effector functions are skewed and fail to protect the host from pathogenic challenge. The present study was performed to evaluate immunomodulatory effect of exposure to Fusobacterium nucleatum(F. nucleatum) prior to Porphyromonas gingivalis(P. gingi - valis). Group 1(control) mice were immunized with phosphate-buffered saline, Group 2 were immunized with F. nucleatum prior to P. gingivalis, while Group 3 were immunized P. gingivalis alone. All the T cell clones derived from Group 2 demonstrated type 2 helper T cell clone(Th2 subsets), while those from Group 3 mice demonstrated Th1 subsets. Exposure of mice to F . nucleatum prior to P. gingivalis interfered with opsonophagocytosis function of sera against P. gingivalis. In adoptive T cell transfer experiments, in vivo protective capacity type 2 helper T cell clones(Th2) from Group 2 was significantly lower than type 1 helper T cell clones(Th1) from Group 3 against the lethal dose infection of P. gingivalis. Western blot analysis indicated the different pattern of recognition of P .gingivalis fimbrial proteins between sera from Group 2 and Group 3. In conclusion, these study suggest that colonization of the subgingival niche by F .nucleatum prior to the periodontal pathogen, P. gingivalis, modulates the host immune responses to P. gingivalis at humoral, cellular and molecular levels.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.69-89
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• 2006

Biological mechanisms for ionizing radiation effects are different at low doses than at high doses. Radiation hormesis involves low-dose-induced protection and high-dose-induced harm. The protective component is associated with a reduction in the incidence of cancer below the spontaneous frequency, brought about by activation of defensive and repair processes. The Linear No-Threshold (LNT) hypothesis advocated by the International Commission on Radiological Protection (ICRP) and the Biological Effects of ionizing Radiation (BEIR) Report VII for cancer risk estimations Ignores hormesis and the presence of a threshold. Cancer incidences significantly less than expected have been found in a large number of epidemiological studies including, airline flight personnel, inhabitants of high radiation backgrounds, shipyard workers, nuclear site workers in scores of locations throughout the world, nuclear power utility workers, plutonium workers, military nuclear test site Participants, Japanese A-bomb survivors, residents contaminated by major nuclear accidents, residents of Taiwan living in $^{60}Co$ contaminated buildings, fluoroscopy and mammography patients, radium dial painters, and those exposed to indoor radon. Significantly increased cancer was not found at doses <200 $mSv^*$. Evidence for radiation hormesis was seen in both sexes for acute or chronic exposures, low or high LET radiations, external whole- or partial body exposures, and for internal radionuclides. The ubiquitous nature of the Healthy Worker Effect (HWE)-like responses in cellular, animal and epidemiological studies negates the HWE as an explanation for radiation hormesis. The LNT hypothesis is wrong and does not represent the true nature of the dose-response relationship, since low doses or dose-rates commonly result in thresholds and reduce cancer incidences below the spontaneous rate. Radiation protection organizations should seriously consider the cost and health implications of radiation hormesis.

• BMB Reports
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• v.51 no.11
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• pp.590-595
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• 2018

Parkinson's disease (PD) is a common chronic neurodegenerative disease mainly caused by the death of dopaminergic neurons. However, no complete pharmacotherapeutic approaches are currently available for PD therapies. 1-methyl-4-phenylpyridinium $(MPP^+)$-induced SH-SY5Y neurotoxicity has been broadly utilized to create cellular models and study the mechanisms and critical aspects of PD. In the present study, we examined the role of a novel azetidine derivative, 3-(naphthalen-2-yl(propoxy)methyl)azetidine hydrochloride (KHG26792), against $MPP^+$-induced neurotoxicity in SH-SY5Y cells. Treatment of KHG26792 significantly attenuated $MPP^+$-induced changes in the protein levels of Bcl-2 and Bax together with efficient suppression of $MPP^+$-induced activation of caspase-3 activity. KHG26792 also attenuated mitochondrial potential and levels of ROS, $Ca^{2+}$, and ATP in $MPP^+$-treated SH-SY5Y cells. Additionally, KHG26792 inhibited the induced production of nitric oxide and malondialdehyde. Moreover, the protective effect of KHG26792 is mediated through regulation of glutathione peroxidase and GDNF levels. Our results suggest a possibility that KHG26792 treatment significantly protects against $MPP^+$-induced neurotoxicity in SH-SY5Y cells and KHG26792 may be a valuable therapeutic agent for the treatment of PD induced by an environmental toxin.