title: Lysosomal dysfunction on hydrogen peroxide-induced apoptosis of osteoarthritic chondrocytes.
abstract: The purpose of this study was to examine the mechanism of hydrogen peroxide-induced apoptosis in osteoarthritic chondrocytes. We evaluated the reactive oxygen species (ROS) formation, lysosomal staining and dysfunction of the mitochondrial membrane potential in these cells after exposure to hydrogen peroxide. Osteoarthritic chondrocytes were isolated, and divided into 4 dishes in which different concentrations (0.1 mM, 1 mM and 10 mM) of hydrogen peroxide, or no additive (control) was added. The cells were incubated for 1 or 4 h, then assayed for ROS formation, mitochondrial membrane potential and lysosomal staining. ROS formation was detected in chondrocytes after 1 h of exposure to hydrogen peroxide concentrations over 0.1 mM. Lysosomal swelling was detected after 1 h of exposure to hydrogen peroxide concentrations of 0.1 mM and over, possibly revealing lysosomal membrane instability. Moreover, indications of lysosomal rupture, including release of lysosomal enzymes, were apparent 1 h after addition of 10 mM of hydrogen peroxide. The addition of hydrogen peroxide to chondrocytes induces ROS formation and lysosomal dysfunction, revealed by swelling and rupture, prior to dysfunction of the mitochondrial membrane potential. Anti-oxidants may have a therapeutic application in the prevention of lysosomal dysfunction to inhibit chondrocyte apoptosis and degradation of the cartilage matrix.
authors.affiliation: Department of Orthopaedics, Medical School, Kochi University, Oko-cho, Nankoku, Kochi 783-8505, Japan. takahast@kochi-ms.ac.jp
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Kitaoka
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Harumichi
authors.initials: H
authors.lastname: Seguchi
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tani
authors.forename: Shoji
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D002356:Cartilage / Q000473:pathology; D002470:Cell Survival; D019902:Chondrocytes / Q000378:metabolism / Q000473:pathology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D008247:Lysosomes / Q000378:metabolism*; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology*; D016877:Oxidants / Q000378:metabolism; D017382:Reactive Oxygen Species; D013997:Time Factors
chemical_list: D000975:Antioxidants; D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide