Mc. Honorati et al., High in vivo expression of interleukin-17 receptor in synovial endothelialcells and chondrocytes from arthritis patients, RHEUMATOLOG, 40(5), 2001, pp. 522-527
Objective. To evaluate the presence of interleukin-17 (IL-17) and the expre
ssion of IL-17 receptor (IL-17R) in joint tissues from subjects with differ
ent arthritides.
Methods. Immunohistochemistry was used on frozen synovial and cartilage bio
psies 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 syno
vial biopsies evaluated except for three cases of post-traumatic arthritis
(PTA). Vascular endothelial cells mainly expressed IL-17R. The percentage o
f IL-17R(+) vessels was the highest in RA synovium and the lowest in PTA. C
hondrocytes 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 fo
und in the majority of patients with different types of arthritis. This fin
ding suggests a role for a second ligand for IL-17R, which could be either
a different cytokine or a different isoform of IL-17.