title: Differential gene expression in anterior and posterior annulus fibrosus.
abstract: METHODS
  Laboratory study.
  
  
  OBJECTIVE
  To evaluate the differential gene expression of cytokines and growth factors in anterior versus posterior annulus fibrosus (AF) intervertebral disc (IVD) specimens.
  
  
  BACKGROUND
  Histological analysis has demonstrated regional differences in vascular and neural ingrowth in the IVD, and similar differences may exist for cytokine and growth factor expression in patients with degenerative disc disease (DDD). Regional expression of these cytokines may also be related to the pain experienced in DDD.
  
  
  METHODS
  IVD tissue was obtained from patients undergoing anterior lumbar interbody fusion surgery for back pain with radiological evidence of disc degeneration. For a control group, the discs of patients undergoing anterior lumbar discectomy for degenerative scoliosis were obtained as well. The tissue was carefully removed and separated into anterior and posterior AF. After tissue processing, an antibody array was completed to determine expression levels of 42 cytokines and growth factors.
  
  
  RESULTS
  Nine discs from 7 patients with DDD and 5 discs from 2 patients with scoliosis were analyzed. In the DDD group, there were 10 cytokines and growth factors with significantly increased expression in the posterior AF versus the anterior AF ([interleukin] IL-4, IL-5, IL-6, M-CSF, MDC, tumor necrosis factor β, EGF, IGF-1, angiogenin, leptin). In the scoliosis group, only angiogenin and PDGF-BB demonstrated increased expression in the posterior AF. No cytokines or growth factors had increased expression in the anterior AF compared with posterior AF.
  
  
  CONCLUSIONS
  The posterior AF expresses increased levels of cytokines and growth factors compared with the anterior AF in patients with DDD. This differential expression may be important for targeting treatment of painful IVDs.
  
  
  METHODS
  N/A.
authors.affiliation: *Department of Orthopaedics, Thomas Jefferson University, Philadelphia, PA †Rothman Institute, Philadelphia, PA; and ‡Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA.
authors.forename: John D
authors.initials: JD
authors.lastname: Koerner
authors.forename: Dessislava Z
authors.initials: DZ
authors.lastname: Markova
authors.forename: Sanjay
authors.initials: S
authors.lastname: Yadla
authors.forename: Joseph
authors.initials: J
authors.lastname: Mendelis
authors.forename: Alan
authors.initials: A
authors.lastname: Hilibrand
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Vaccaro
authors.forename: Makarand V
authors.initials: MV
authors.lastname: Risbud
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Albert
authors.forename: D Greg
authors.initials: DG
authors.lastname: Anderson
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Kepler
mesh_terms: D000328:Adult; D000368:Aged; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged
chemical_list: D016207:Cytokines; D036341:Intercellular Signaling Peptides and Proteins