title: High in vivo expression of interleukin-17 receptor in synovial endothelial cells and chondrocytes from arthritis patients.
abstract: OBJECTIVE
  To evaluate the presence of interleukin-17 (IL-17) and the expression of IL-17 receptor (IL-17R) in joint tissues from subjects with different arthritides.
  
  
  METHODS
  Immunohistochemistry was used on frozen synovial and cartilage biopsies to identify cells expressing IL-17 and IL-17R.
  
  
  RESULTS
  IL-17 staining was present only in synovial biopsies of rheumatoid arthritis (RA) (seven out of nine cases). IL-17R was expressed by all synovial biopsies evaluated except for three cases of post-traumatic arthritis (PTA). Vascular endothelial cells mainly expressed IL-17R. The percentage of IL-17R(+) vessels was the highest in RA synovium and the lowest in PTA. Chondrocytes from all types of arthritides were negative for IL-17 staining, but expressed IL-17R; the highest percentage of positive chondrocytes was found in seronegative spondylarthritis and the lowest in RA.
  
  
  CONCLUSIONS
  IL-17-positive cells are found exclusively in RA. On the other hand, synovial endothelial cells and chondrocytes expressing IL-17R are found in the majority of patients with different types of arthritis. This finding suggests a role for a second ligand for IL-17R, which could be either a different cytokine or a different isoform of IL-17.
authors.affiliation: Laboratorio Immunologia e Genetica, Istituto Codivilla Putti-IOR, Via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Honorati
authors.forename: R
authors.initials: R
authors.lastname: Meliconi
authors.forename: L
authors.initials: L
authors.lastname: Pulsatelli
authors.forename: S
authors.initials: S
authors.lastname: Canè
authors.forename: L
authors.initials: L
authors.lastname: Frizziero
authors.forename: A
authors.initials: A
authors.lastname: Facchini
mesh_terms: D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism; D001168:Arthritis / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D019902:Chondrocytes / Q000378:metabolism* / Q000473:pathology; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008297:Male; D008875:Middle Aged; D020395:Receptors, Interleukin-7 / Q000378:metabolism*; D013583:Synovial Membrane / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology
chemical_list: D015703:Antigens, CD; D020395:Receptors, Interleukin-7