Ph.D Thesis


Ph.D StudentCarmel Julia
SubjectInvolvement of Cytokins and Growth Factors in Degradation
and Synthesis in Articular Cartilage
DepartmentDepartment of Medicine
Supervisor MRS Erella Livne (Deceased)


Abstract

Interleukin 1b (IL-1b) was suggested to be involved in the destruction of joint tissues. Matrix metalloproteinases (MMPs) are the major proteinases involved in the pathologic degradation of cartilage matrix. In contrast to IL-1, TGF-b1 induces cell proliferation and PG synthesis in cartilage and stimulates cartilage repair.

The purpose of the present study was to test the in vitro effects of IL-1 on metabolic markers and on MMPs activity in articular cartilage and to test the ability of TGF-b to diminish these effects.

Temporomandibular (TMJ) condyle and knee joint cartilages (femoral condyle and tibial plateau) of 3-month-old ICR mice were dissected and cultured in BGJb medium in the presence 50-3000 U/ml (0.25-25 ng/ml) of IL-1b for 3&6 days. In some groups TGF-b1 was added after 3 days of exposure to IL-1b so that the last 3 days the these groups were treated by combination of IL-1 and TGF-b1.

Results indicated that IL-1b caused significant reduction of 35S-sulfate and 3H-thymidine incorporation in TMJ and tibial cartilages, and that TGF-b1 partly reversed this effect. IL-1b induced elevation of MMP-2, MMP-9 and MMP-13 activity in homogenate and medium of all cartilages tested. It has been also shown that TGF-b reduced MMPs activation caused by IL-1b treatment only in tissue homogenate but not in culture medium.

Morphology revealed cartilage destruction, cell reduction, atypical hypertrophy and loss of PG content under IL-1b effect that was partially restored after treatment by TGF-b. Additionally, effect of IL-1 was found to vary according to the different cartilages tested.

It is concluded that IL-1b stimulated catabolic activity in joint cartilages as shown by activation of MMPs, by reduction of cell proliferation and PG synthesis and by tissue destruction. TGF-b partially restored these effects.