Correlation Between Osteopontin Synovial Expression & Angiogenesis in JRA

[Guest guest]

Correlation Between Osteopontin Synovial Expression and Angiogenesis in

Juvenile Idiopathic Arthritis

PURPOSE: Osteopontin (OPN) is an extracellular matrix protein which

interact with integrins, promoting cell attachment, cell migration and

angiogenesis. Aim of the present study was to evaluate the synovial

expression of OPN and its possible correlation with angiogenesis in

chronic synovitis.

METHODS: Forty-five patients (21 polyarticular course, 23 persistent

oligoarticular course) with active JIA were studied. All the patients

underwent to SF needle aspiration before local therapeutic injection

with steroids.

A paired plasma sample was collected in 22 JIA patients (11 poly, 11

oligo). Fifteen age-matched healthy subjects were used as controls.

Plasma and SF were tested by a commercial ELISA for OPN (DRG, D),

Stromelysin-1 (Amersham, UK), and VEGF. Synovial tissue (ST) were

obtained at synoviectomy or arthroplasty from 6 JIA patients.

Immunohistochemical study was performed according to standard technique

with anti-CD68 (Dako, Denmark), anti-CD31 (Dako), anti-OPN (Abcam, UK)

and anti-VEGF (Santa Cruz Biot., USA) antibodies. For each SM, three

representative serial fields were evaluated for each parameter. Results

were calculated as number of positive cells or vessels/high power field

(hpf/40x).

RESULTS: OPN levels were significantly higher in SF in respect to paired

plasma. The same pattern was observed also for MMP-3 and VEGF

concentrations. In fact, SF MMP-3 and VEGF concentrations were higher

than those detected in paired plasma.

CONCLUSIONS: OPN synovial expression correlate with angiogenesis in JIA.

These data seem to confirm, in human disease, the possible pivotal role

of OPN for pannus growth and vascularization, as previously shown in

OPN-deficient animal models of arthritis.

Marco Gattorno1, Gregorio1, Francesca Ferlito1, Valeria Gerloni2,

Antonina Parafioriti2, Enrico Felici1, Lucia Trail1, Paolo Picco1,

Claudio Gambini1, Alberto i1. 1G. Gaslini, Genoa, Italy; 2G. Pini,

Milan, Italy