title: Mechanical force-mediated pathological cartilage thinning is regulated by necroptosis and apoptosis.
abstract: This study aimed to identify the mechanisms underlying mandibular chondrocyte cell death and cartilage thinning in response to mechanical force.
  
  
  
  An in vivo model (compressive mechanical force) and an in vitro model (TNF-α+cycloheximide) were used to induce mandibular chondrocyte necroptosis. Hematoxylin and eosin staining and transmission electron microscopy were used to assess histological and subcellular changes in mandibular chondrocyte. Immunohistochemistry, western blotting, and real-time PCR were performed to evaluate changes in necroptotic protein markers. Cell activity, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were examined in vitro.
  
  
  
  The expression of RIP1, RIP3 and Caspase-8 in mandibular chondrocytes significantly increased after 4 days of compressive mechanical force. Furthermore, the inhibition of necroptosis by Necrostatin-1 (Nec-1) or the inhibition of apoptosis by N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD) partially restored mechanical force-mediated mandibular cartilage thinning and chondrocyte death. Moreover, a synergistic effect on cell death inhibition and mandibular cartilage thickness restoration were found when treated with Nec-1+Z-VAD. The results of the in vitro model were in line with the in vivo ones, indicating that the changes in MMP and ROS generation contributed to mandibular chondrocyte apoptosis and necroptosis.
  
  
  
  In addition to apoptosis, necroptosis also plays critical roles in pathological changes in mandibular cartilage after compressive mechanical force stimulation, implying RIP1, a master protein that mediates both necroptosis and apoptosis, as a potential therapeutic target in temporal mandibular osteoarthritis.
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: S
authors.initials: S
authors.lastname: Lin
authors.affiliation: Department of Biostatistics, Robert Stempel College of Public Health and Social Work, Florida International University, USA.
authors.forename: T
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: J
authors.initials: J
authors.lastname: Wen
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China.
authors.forename: W
authors.initials: W
authors.lastname: Cheng
authors.affiliation: Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, China. Electronic address: lihuang76@nju.edu.cn.
authors.forename: H
authors.initials: H
authors.lastname: Li
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology; D002358:Cartilage, Articular / Q000473:pathology* / Q000502:physiology; D053181:Caspase 8 / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000473:pathology; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008334:Mandible / Q000737:chemistry / Q000502:physiology; D053078:Membrane Potential, Mitochondrial; D009336:Necrosis; D009842:Oligopeptides / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism; D013314:Stress, Mechanical; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D007093:Imidazoles; D007211:Indoles; D009842:Oligopeptides; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C517629:benzyloxycarbonyl-valyl-alanyl-aspartic acid; C507699:necrostatin-1; D017346:Protein Serine-Threonine Kinases; C586536:RIPK1 protein, rat; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C582791:Ripk3 protein, rat; D053181:Caspase 8
keywords: Apoptosis; Compressive mechanical force; Mandibular cartilage; Mandibular chondrocyte; Necroptosis