title: Toll-like receptor 9 is correlated to disease activity in Chinese systemic lupus erythematosus population.
abstract: BACKGROUND
  Toll like receptor (TLR) 9 has been shown to play a crucial role in the pathogenesis of systemic lupus erythematosus (SLE) in animal models. Its pathogenic role in human SLE, however, was poorly elucidated. This study was performed to investigate the role of TLR9 involved in the aberrant signaling pathway and its correlation with disease activity in SLE.
  
  
  METHODS
  mRNA level of TLR9 and interferon (IFN) regulatory factor 5 (IRF5) in peripheral blood mononuclear cells (PBMCs) were determined by real-time polymerase chain reaction (PCR). IFN-a expression was measured in the serum of the SLE patients by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  TLR9 expression was significantly higher in SLE patients than that in health controls (P = 0.011). SLE patients with positive anti-dsDNA antibody had significantly higher expression of TLR9 than that with negative anti-dsDNA antibody (P = 0.001). TLR9 expression was positively correlated with fever (P = 0.017), alopecia (P = 0.046), safety of estrogens in lupus erythematosus national assessment SLE disease activity index (SELENA-SLEDAI) score (r(s) = 0.385, P = 0.003), and the level of IRF5 (r(s) = 0.35, P = 0.027) and IFN-a (r(s) = 0.627, P = 0.001) in SLE patients.
  
  
  CONCLUSIONS
  TLR9 is associated with SLE disease activity and might be involved in the IFN-a pathway of SLE.
authors.affiliation: Department of Rheumatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Mu
authors.forename: Xiao-Yun
authors.initials: XY
authors.lastname: Sun
authors.forename: Lik Thai
authors.initials: LT
authors.lastname: Lim
authors.forename: Chuan-Hui
authors.initials: CH
authors.lastname: Xu
authors.forename: Chen-Xian
authors.initials: CX
authors.lastname: Dai
authors.forename: Yin
authors.initials: Y
authors.lastname: Su
authors.forename: Ru-Lin
authors.initials: RL
authors.lastname: Jia
authors.forename: Zhan-Guo
authors.initials: ZG
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D050835:Interferon Regulatory Factors / Q000378:metabolism; D016898:Interferon-alpha / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D060888:Real-Time Polymerase Chain Reaction; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism*; D055815:Young Adult
chemical_list: D000974:Antibodies, Antinuclear; C431713:IRF5 protein, human; D050835:Interferon Regulatory Factors; D016898:Interferon-alpha; D051217:Toll-Like Receptor 9