title: Hyperbaric oxygen treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells.
abstract: Nucleus pulposus cells (NPCs) from degenerating discs produce catabolic and inflammatory factors, including interleukin (IL)-1 and nitric oxide (NO). Enhanced production of NO has been implicated in the apoptosis of degenerating disc cells. This study evaluates the effects of hyperbaric oxygen (HBO) on degenerated human NPCs. All hyperoxic cells were exposed to 100% O(2) at 2.5 atmospheres absolute (ATA). Phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) in NPCs was detected using the phosphor-kinase array kit. RNA was isolated for real-time polymerase chain reaction (PCR) analysis of aggrecan and type II collagen gene expression. The levels of IL- 1β and NO were quantified by enzyme-linked immunosorbent assay (ELISA). To identify the HBO-induced anti-apoptotic pathways, expression of Bcl-2 and Bax proteins as well as activation of cysteine-containing aspartate-specific proteases (caspases) 3, 8, and 9 was evaluated using Western blotting after HBO treatment. Our data showed that HBO treatment decreased the expression of IL-1β, suppressed phosphorylation of ERK1/2, JNK, and p38 MAPK, decreased synthesis of NO, and increased the gene expression of aggrecan and type II collagen in NPCs as compared with the atmospheric treatment. HBO up-regulated the ratio of Bcl-2 to Bax expression and reduced the activity of caspases 9 and 3 but not of caspase 8, indicating a selective effect over the mitochondrial apoptosis pathway in degenerated NPCs. These results support our hypothesis that HBO treatment suppresses MAPK signaling and mitochondrial apoptotic pathway in degenerated human intervertebral disc cells.
authors.affiliation: Department of Orthopaedic Surgery, Hyperbaric Oxygen Therapy Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Chi-Chien
authors.initials: CC
authors.lastname: Niu
authors.forename: Song-Shu
authors.initials: SS
authors.lastname: Lin
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Yuan
authors.forename: Lih-Huei
authors.initials: LH
authors.lastname: Chen
authors.forename: I-Chun
authors.initials: IC
authors.lastname: Wang
authors.forename: Tsung-Ting
authors.initials: TT
authors.lastname: Tsai
authors.forename: Po-Liang
authors.initials: PL
authors.lastname: Lai
authors.forename: Wen-Jer
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D053674:Aggrecans / Q000096:biosynthesis; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000096:biosynthesis; D024043:Collagen Type II / Q000096:biosynthesis; D006801:Humans; D006931:Hyperbaric Oxygenation; D053583:Interleukin-1beta / Q000096:biosynthesis; D007403:Intervertebral Disc / Q000503:physiopathology; D055959:Intervertebral Disc Degeneration / Q000503:physiopathology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008928:Mitochondria / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D053674:Aggrecans; D024043:Collagen Type II; D053583:Interleukin-1beta; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D009569:Nitric Oxide; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases