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344 results on '"Choi, Bong-Kyu"'

66. In Vivo Inhibition of Porphyromonas gingivalis Growth and Prevention of Periodontitis With Quorum-Sensing Inhibitors.

Author

Cho, Young‐Jae, Song, Hyun Young, Ben Amara, Heithem, Choi, Bong‐Kyu, Eunju, Ryu, Cho, Young‐Ah, Seol, Yangjo, Lee, Yongmoo, Ku, Young, Rhyu, In‐Chul, Koo, Ki‐Tae, Cho, Young-Jae, Choi, Bong-Kyu, Cho, Young-Ah, Rhyu, In-Chul, and Koo, Ki-Tae

Abstract

Background: Autoinducer (AI)-2 has an important role in biofilm formation in the oral environment. Mature biofilms formed as a result of the cell-to-cell communication make it difficult to overcome periodontitis with the use of antibiotics. Previous in vitro studies suggest that quorum-sensing inhibitors (QSIs) interfere with AI-2. This study compares the QSI effects resulting from an oral inoculation of Porphyromonas gingivalis in an experimental animal model.Methods: Forty-five male mice were divided into three groups (n = 15 each): 1) infection; 2) QSI; and 3) control. Infection and QSI groups received oral inoculation of P. gingivalis, whereas treatment with QSIs (furane compound and d-ribose) was only performed in the QSIs group. The control group was a negative control not receiving manipulation. After 42 days, mice were sacrificed, and the distance from the alveolar bone crest (ABC) to the cemento-enamel junction (CEJ) was measured by microcomputed tomography. P. gingivalis DNA was quantified in the soft and hard tissues around the molar teeth by real-time polymerase chain reaction.Results: Distance from ABC to CEJ was significantly increased in the P. gingivalis infection group compared with the control group (P = 0.02) and significantly decreased in the QSI group compared with the infection group (P = 0.02). The QSI group contained 31.64% of the bacterial DNA count of the infection group.Conclusion: Use of QSIs in the mice infection model showed a reduction of bone breakdown and a decrease in the number of bacteria in vivo, suggesting that QSIs can be a new approach to prevention and treatment of periodontitis. [ABSTRACT FROM AUTHOR]

Published
2016
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74. Caspase-4 activation by a bacterial surface protein is mediated by cathepsin G in human gingival fibroblasts

Author

Jun, Hye-Kyoung, Jung, Young-Jung, Ji, Suk, An, Sun-Jin, and Choi, Bong-Kyu

Abstract

Caspase-4 is an inflammatory caspase; however, its mechanism of activation is poorly understood. In this study, we demonstrate that Td92, a surface protein of the periodontal pathogen Treponema denticola and a homolog of the Treponema pallidum surface protein Tp92, activates caspase-4 and induces pyroptosis in primary cultured human gingival fibroblasts (HGFs) via cathepsin G activation. Cathepsin G inhibition or siRNA knockdown of cathepsin G inhibited Td92-induced caspase-4 activation and cell death. Td92-induced cell death was significantly inhibited by siRNA knockdown of gasdermin D. Td92 treatment resulted in the binding of cathepsin G to caspase-4 and the coaggregation of these two molecules. In addition, Td92 induced IL-1a expression and secretion, and this was inhibited by caspase-4 knockdown. Cytochalasin D did not block Td92-induced caspase-4 activation, suggesting that Td92 internalization is not required for caspase-4 activation. Our results demonstrate that cathepsin G is directly engaged in caspase-4 activation by a bacterial ligand, which is responsible for cell death and IL-1a secretion in HGFs.

Published
2018
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82. In SilicoDevelopment of Quorum‐Sensing Inhibitors

Author

Byeon, Jae‐Young, Sim, Jun, Ryu, Eun‐Ju, Sim, Jaehyun, Lee, Hwan, Cho, Kwang‐Hwi, Choi, Bong‐Kyu, and Lee, Julian

Abstract

Quorum sensing (QS) is a chemical communication between bacteria, with which bacteria sense the population of their own species. Autoinducer‐2 (AI‐2) is a class of universal quorum‐sensing molecules, which is used by both Gram‐negative and Gram‐positive bacteria. The inhibition of AI‐2‐mediated QS has various practical applications, including the prevention of the formation of biofilm in dental gums. In this work, we develop a computational protocol for developing AI‐2 inhibitors. A challenging aspect of such an endeavor is that the receptor undergoes a large conformational change upon ligand binding. We combine several methods such as molecular docking with multiple conformations, molecular dynamics simulations, and molecular mechanics Poisson–Boltzmann computation, in order to estimate binding affinity of candidate molecules to a quorum‐sensing receptor. We apply our method to rank the substances in a chemical library. We indeed find a molecule that has a higher affinity than previously known ligands, thus showing the feasibility of the protocol for the development of quorum‐sensing inhibitors.

Published
2017
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93. Contradictory roles of P orphyromonas gingivalis gingipains in caspase-1 activation.

Author

Jung, Young‐Jung, Jun, Hye‐Kyoung, and Choi, Bong‐Kyu

Subjects
PORPHYROMONAS gingivalis, CASPASES, IMMUNE system, MACROPHAGES, LACTATE dehydrogenase, INTERLEUKIN-1
Abstract

P orphyromonas gingivalis utilizes its major proteases, Arg gingipains ( RgpA and RgpB) and Lys gingipain ( Kgp), for dysregulation of host immune systems. The aim of this study was to investigate the roles of gingipains in caspase-1 activation and its sequelae in P . gingivalis-infected macrophages. Infection with P . gingivalis at low multiplicity of infections ( MOIs), but not at high MOIs, resulted in low levels of interleukin-1β and lactate dehydrogenase without detectable active caspase-1 in the culture supernatants. The proteins released from caspase-1-activated cells were rapidly degraded by gingipains. However, P . gingivalis with gingipains induced higher intracellular caspase-1 activity in the infected cells than the gingipain-null mutant, which was associated with ATP release from the infected cells. In addition, growing the gingipain-null mutant with gingipains enhanced caspase-1 activation by the mutant. In contrast, inhibition of the protease activity of Kgp or Rgps increased the caspase-1-activating potential of wild-type P . gingivalis, indicating an inhibitory effect of the collaborative action of Kgp and Rgps. These results illuminate the contradictory roles of gingipains in the manipulation of host defence systems by P . gingivalis, as they act by both stimulating and inhibiting innate immune responses. [ABSTRACT FROM AUTHOR]

Published
2015
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95. Amino acid transport system L is differently expressed in human normal oral keratinocytes and human oral cancer cells

Author

Yoon, Jung Hoon, primary, Kim, In Jin, additional, Kim, Hyun, additional, Kim, Heung-Joong, additional, Jeong, Moon Jin, additional, Ahn, Sang Gun, additional, Kim, Soo A, additional, Lee, Chong Heon, additional, Choi, Bong Kyu, additional, Kim, Jong-Keun, additional, Jung, Kyu Yong, additional, Lee, Seoul, additional, Kanai, Yoshikatsu, additional, Endou, Hitoshi, additional, and Kim, Do Kyung, additional

Published
2005
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