title: Serum levels of IL-33 and soluble ST2 and their association with disease activity in systemic lupus erythematosus.
abstract: OBJECTIVE
  IL-33 has recently been found to be the specific ligand of ST2, an IL-1 receptor family member that is selectively expressed in Th2 cells and mediates Th2 response. This study aims to measure the serum levels of soluble ST2 (sST2) and IL-33 in patients with SLE and to examine their association with disease activity.
  
  
  METHODS
  Seventy SLE patients were evaluated for disease activity, determined by SLEDAI, levels of anti-dsDNA antibody, C3 and C4. Fifty-seven patients were evaluated longitudinally on a second occasion. IL-33 and sST2 were measured by sandwich ELISA in the 127 SLE serum samples and compared with 28 age- and sex-matched healthy controls.
  
  
  RESULTS
  Serum sST2 level was significantly higher in active SLE patients [0.51 (0.18) ng/ml] compared with inactive patients [0.42 (0.08) ng/ml] (P = 0.006) and normal controls [0.36 (0.13) ng/ml] (P < 0.001). sST2 level correlated significantly with SLEDAI, anti-dsDNA antibody and prednisolone dosage, and negatively with C3. Linear regression analysis showed that serum sST2 level was an independent predictive factor for modified SLEDAI, excluding anti-dsDNA and complement score after controlling for age, sex, glomerular filtration rate and prednisolone dosage (regression coefficient: 8.5; 95% CI 2.6, 14.3) (P = 0.005). Serum sST2 level was sensitive to change in disease activity longitudinally, with an effect size of 0.29. Elevated serum IL-33 was comparable in frequency (4.3 vs 7.1%; P = 0.62) and levels (P = 0.53) between SLE patients and controls.
  
  
  CONCLUSIONS
  Elevated serum sST2 level in SLE patients was found to correlate with disease activity and was sensitive to change, suggesting a potential role as a surrogate marker of disease activity.
authors.affiliation: Department of Medicine, Queen Mary Hospital, Hong Kong. temy@hkucc.hku.hk
authors.forename: Mo Yin
authors.initials: MY
authors.lastname: Mok
authors.forename: Fang Ping
authors.initials: FP
authors.lastname: Huang
authors.forename: Wai Ki
authors.initials: WK
authors.lastname: Ip
authors.forename: Yi
authors.initials: Y
authors.lastname: Lo
authors.forename: Fung Yi
authors.initials: FY
authors.lastname: Wong
authors.forename: Eric Yuk Tat
authors.initials: EY
authors.lastname: Chan
authors.forename: Kwok Fai
authors.initials: KF
authors.lastname: Lam
authors.forename: Damo
authors.initials: D
authors.lastname: Xu
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D015415:Biomarkers / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004812:Epidemiologic Methods; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011239:Prednisolone / Q000008:administration & dosage; D011956:Receptors, Cell Surface / Q000097:blood*
chemical_list: D000974:Antibodies, Antinuclear; D015415:Biomarkers; D005938:Glucocorticoids; C079241:IL1RL1 protein, human; C506536:IL33 protein, human; D007166:Immunosuppressive Agents; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins; D011956:Receptors, Cell Surface; D011239:Prednisolone