title: Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage.
abstract: Hyaluronic acid (HA) is used clinically to treat osteoarthritis (OA), but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and dimethylmethylene blue (DMMB) assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α). These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. katsura@koto.kpu-m.ac.jp.
authors.forename: Shohei
authors.initials: S
authors.lastname: Ichimaru
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. shushi@koto.kpu-m.ac.jp.
authors.forename: Shuji
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Department of Sports and Para-Sports Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. yarai89046@nike.eonet.ne.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.affiliation: Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. tsunao@koto.kpu-m.ac.jp.
authors.forename: Tsunao
authors.initials: T
authors.lastname: Kishida
authors.affiliation: Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. masaharu@koto.kpu-m.ac.jp.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Shin-Ya
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. kuniakih@koto.kpu-m.ac.jp.
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Honjo
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. tuchi-kf@koto.kpu-m.ac.jp.
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsuchida
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. hinoue@koto.kpu-m.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Inoue
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. fjwr@koto.kpu-m.ac.jp.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. s-shimo@koto.kpu-m.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Shimomura
authors.affiliation: Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. mazda@koto.kpu-m.ac.jp.
authors.forename: Osam
authors.initials: O
authors.lastname: Mazda
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. tkubo@koto.kpu-m.ac.jp.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism; D006820:Hyaluronic Acid / Q000494:pharmacology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016326:Extracellular Matrix Proteins; C497444:Hif1a protein, rat; D018960:Hyaluronan Receptors; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D006820:Hyaluronic Acid; D010100:Oxygen
keywords: CD44; articular cartilage; extracellular matrix; hyaluronic acid; hypoxia-inducible factor 1 α