title: Increased serum interleukin 22 in patients with rheumatoid arthritis and correlation with disease activity.
abstract: OBJECTIVE
  To analyze the role of interleukin 22 (IL-22) in rheumatoid arthritis (RA).
  
  
  METHODS
  IL-22 serum levels were measured in 83 patients with established RA under treatment with disease-modifying antirheumatic drugs and in 30 healthy controls matched for age and sex. Patients were assessed for clinical and laboratory variables. Correlations of IL-22 serum levels with disease activity measures [Clinical Disease Activity Index (CDAI) and Disease Activity Score for 28 joints (DAS28)], serological markers, bone erosions, and demographic factors were assessed. Peripheral blood mononuclear cells (PBMC) from 30 patients with RA and 14 controls were purified and stimulated in vitro with phorbol myristate acetate (PMA)/ionomycin. IL-22 production by PBMC and in serum was investigated by ELISA.
  
  
  RESULTS
  IL-22 levels were increased in patients with RA compared with controls (mean 432.37 pg/ml and 67.45 pg/ml, respectively; p < 0.001). Levels of IL-22 correlated with DAS28 and CDAI measures. Rheumatoid factor (RF) positivity was correlated with higher levels of IL-22 in patients with RA (mean 575.08 pg/ml; p = 0.001). The presence of bone erosions was associated with high IL-22 levels (p = 0.0001). PBMC stimulated with PMA/ionomycin expressed higher levels of IL-22 in patients with RA than controls but this was not significant (mean 584.75 pg/ml and 295.57 pg/ml; p = 0.553).
  
  
  CONCLUSIONS
  IL-22 is elevated in the serum of patients with established RA. Elevated serum IL-22 allows discrimination between patients with different clinical and laboratory measures and indicates the potential of IL-22 as an additional tool for assessment of activity in RA, particularly in patients with RF antibodies and longterm disease. IL-22 is associated with bone-destructive disease.
authors.affiliation: Universidade Federal de Pernambuco (UFPE), Recife, Brazil.
authors.forename: Laurindo Ferreira
authors.initials: LF
authors.lastname: da Rocha
authors.forename: Ângela Luzia Branco Pinto
authors.initials: ÂL
authors.lastname: Duarte
authors.forename: Andréa Tavares
authors.initials: AT
authors.lastname: Dantas
authors.forename: Henrique Ataíde
authors.initials: HA
authors.lastname: Mariz
authors.forename: Ivan da Rocha
authors.initials: Ida R
authors.lastname: Pitta
authors.forename: Suely Lins
authors.initials: SL
authors.lastname: Galdino
authors.forename: Maira Galdino da Rocha
authors.initials: MG
authors.lastname: Pitta
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy; D061207:Calcium Ionophores / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D018450:Disease Progression; D005260:Female; D006801:Humans; D007378:Interleukins / Q000097:blood*; D015759:Ionomycin / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000097:blood / Q000188:drug therapy; D012217:Rheumatoid Factor / Q000097:blood; D012720:Severity of Illness Index; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000097043:Interleukin-22
chemical_list: D018501:Antirheumatic Agents; D061207:Calcium Ionophores; D002273:Carcinogens; D007378:Interleukins; D015759:Ionomycin; D012217:Rheumatoid Factor; D013755:Tetradecanoylphorbol Acetate; D000097043:Interleukin-22