title: TNF-α induced down-regulation of lysyl oxidase family in anterior cruciate ligament and medial collateral ligament fibroblasts.
abstract: BACKGROUND
  The lysyl oxidase (LOX) family has the capacity to catalyze the cross-linking of collagen and elastin, implicating its important fundamental role in injury healing. Tumor necrosis factor alpha (TNF-α) is considered to be an important chemical mediator in the acute inflammatory phase of the ligament injury. The role of the lysyl oxidase family induced by TNF-α in the knee ligaments' wound healing process is poorly understood. Our purpose was to determine the different expressions of the LOXs in poorly self-healing anterior cruciate ligament (ACL) and well functionally self-healing medial collateral ligament (MCL) induced by TNF-α.
  
  
  METHODS
  Semi-quantitative PCR, quantitative real-time PCR and western blot were performed for original research.
  
  
  RESULTS
  The results showed that all LOX family members were expressed at higher levels in MCL than those in ACL fibroblasts; the significant differences existed in the down-regulations of the LOXs induced by TNF-α; and the TNF-α-mediated down-regulations of the LOXs were more prominent in ACL than those in MCL fibroblasts. 1-20 ng/ml TNF-α down-regulated mRNA levels in ACL and MCL fibroblasts by up to 76% and 58% in LOX; 90% and 45% in LOXL-1; 97.5% and 90% in LOXL-2; 89% and 68% in LOXL-3; 52% and 25% in LOXL-4, respectively. Protein assay also showed LOXs had lower expressions in ACL than those in MCL.
  
  
  CONCLUSIONS
  Based on these results, the differential expressions of the LOXs might help to explain the intrinsic differences between the poorly self-healing ACL and well functionally self-healing MCL.
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China. Electronic address: wxxjj_2001@163.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Xie
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
authors.forename: Jiahuan
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Orthopaedics, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
authors.forename: Chunming
authors.initials: C
authors.lastname: Xu
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
authors.forename: Chunli
authors.initials: C
authors.lastname: Wang
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Yin
authors.affiliation: Department of Bioengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0412, United States; Department of Orthopaedics, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0412, United States.
authors.forename: Peter C Y
authors.initials: PC
authors.lastname: Chen
authors.affiliation: "111" Project Laboratory of Biomechanics and Tissue Repair, Bioengineering College, Chongqing University, Chongqing 400044, China; Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, China; Department of Orthopaedics, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Bioengineering, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0412, United States; Department of Orthopaedics, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0412, United States. Electronic address: klpsung@eng.ucsd.edu.
authors.forename: K L Paul
authors.initials: KL
authors.lastname: Sung
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000166:cytology*; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004587:Electrophoresis, Agar Gel; D005260:Female; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D008297:Male; D017888:Medial Collateral Ligament, Knee / Q000166:cytology*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D008249:Protein-Lysine 6-Oxidase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage*
chemical_list: D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D008249:Protein-Lysine 6-Oxidase
keywords: ACL; Collagen; Lysyl oxidase; MCL; TNF-α