Expression of ICAM-1 by osteoblasts in healthy individuals and in patients suffering from osteoarthritis and osteoporosis.
OBJECTIVE
To describe the pattern of expression of intercellular adhesion molecule-1 (ICAM-1) at the surface of human osteoblasts (Ob) recovered from normal (control), osteoporotic (OP), and osteoarthritic (OA) bone. To relate ICAM-1 expression in OA Ob with interleukin-6 (IL-6) and prostaglandin E2 (PGE2) production.


METHODS
Trabecular bone specimens were taken from patients suffering from OA of the hip (n = 19) or knee (n = 19) or from hip fracture caused by osteoporosis (n = 10). Control bone specimens came from the posterosuperior iliac crest (n = 5) and from the femoral condyle of organ donors (n = 6). Bone explants were digested with collagenase and cultured. Ob were obtained after 6 weeks. ICAM-1 expression was studied by immunocytology. IL-6 and PGE2 were evaluated by standard ELISA.


RESULTS
Average ICAM-1 expression was different between control and OP bone (P < 0.02). Separation of specimens into high and low ICAM-1 expression showed a significant difference between high and low ICAM-1 expressors. The distribution of specimens after subclassification into high or low ICAM-1 expression groups revealed only 18.2% of patients in the high expression group for the controls, compared to 70% for OP bone (P < 0.03), 52.6% for hip OA and 47.4% for knee OA. IL-6 and PGE2 levels in OA Ob from both groups were found to be significantly elevated with high ICAM-1 expression compared to low ICAM-1 expression.


CONCLUSIONS
The results show that ICAM-1 expression in human bone seems to be pathology-dependent and correlates with IL-6 and PGE2 production, at least in OA individuals. This implies that ICAM-1 could discriminate functionally different populations of Ob and possibly alter the clinical evolution of the disease.
Orthopaedics Research Laboratory, Department of Orthopaedics, Centre hospitalier Sacré-Coeur, Montreal, Quebec, Canada.
Patrick
P
Lavigne
Mohamed
M
Benderdour
Daniel
D
Lajeunesse
Qin
Q
Shi
Julio C
JC
Fernandes
D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D010003:Osteoarthritis / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D010024:Osteoporosis / Q000378:metabolism*; D012016:Reference Values
D015850:Interleukin-6; D018799:Intercellular Adhesion Molecule-1; D015232:Dinoprostone