title: Overexpression of osteopontin in rheumatoid synovial mononuclear cells is associated with joint inflammation, not with genetic polymorphism.
abstract: OBJECTIVE
  Osteopontin (OPN) is thought to play an important role in rheumatoid synovitis. We investigated the expression of OPN in rheumatoid synovial fluid mononuclear cells (SFMC) and its potential association with genetic polymorphism of the OPN gene and joint inflammation in rheumatoid arthritis (RA).
  
  
  METHODS
  1. The expression of OPN mRNA in peripheral blood mononuclear cells (PBMC) and SFMC of patients with RA was analyzed quantitatively by real-time polymerase chain reaction (PCR). Results were analyzed in paired PBMC and SFMC and control PBMC. 2. Six single nuclear acid polymorphisms of the OPN gene were genotyped in a cohort of 192 Chinese patients with RA and controls (n = 288) by restriction fragment length polymorphism PCR or direct DNA sequencing. 3. SF derived from RA patients was examined for the stimulating effect on mRNA expression of the OPN gene in PBMC.
  
  
  RESULTS
  The expression of OPN gene was significantly increased in SFMC and, to a lesser degree, in PBMC of patients with RA compared to control PBMC (p < 0.01). However, the prevalence of OPN genotype and allele frequencies at the selected positions did not differ significantly between RA patients and the control group (p > 0.05). Further characterization indicated that SF known to contain a variety of proinflammatory factors significantly stimulated mRNA expression of OPN in PBMC obtained from RA patients or healthy controls.
  
  
  CONCLUSIONS
  Overexpression of OPN mRNA in SFMC is associated with proinflammatory factors produced in inflamed joints, but not with OPN genetic polymorphisms. OPN gene polymorphisms do not correlate with susceptibility to RA.
authors.affiliation: Health Science Center, Shanghai Institutes for Biological Sciences, Shanghai, China.
authors.forename: Guangwu
authors.initials: G
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: Dongyi
authors.initials: D
authors.lastname: He
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Wenxin
authors.initials: W
authors.lastname: Zheng
authors.forename: Hong
authors.initials: H
authors.lastname: Nie
authors.forename: Liqing
authors.initials: L
authors.lastname: Ni
authors.forename: Dongqing
authors.initials: D
authors.lastname: Zhang
authors.forename: Ningli
authors.initials: N
authors.lastname: Li
authors.forename: Jingwu
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D007249:Inflammation / Q000276:immunology*; D007596:Joints / Q000276:immunology / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D053495:Osteopontin; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012795:Sialoglycoproteins / Q000235:genetics* / Q000378:metabolism; D013223:Statistics as Topic; D013583:Synovial Membrane / Q000166:cytology*
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin