Influence of human recombinant interleukin-1 beta on human articular cartilage. Mitotic activity and proteoglycan metabolism.
The effects of human recombinant interleukin-1 beta (IL-1 beta) were investigated on recently isolated (1 to 3 weeks) and on well-established (older than 3 weeks) monolayer cultured human articular chondrocytes. IL-1 beta was found to depress 35S-proteoglycan synthesis rates and to enhance prostaglandin E2 (PGE2) production in these monolayer cultured chondrocytes. Induction of 35S-proteoglycan-degradative activity by these cells also occurred in IL-1 beta treated cultures. These "catabolin" -IL-1 activities were observed in recently isolated as well as in well-established "old" cultures. IL-1 beta increased 3H-thymidine incorporation rates in the "old" cultures. However, in recently isolated chondrocytes a dose-dependent reduction of the 3H-thymidine incorporation occurred. The depression of mitotic activity in these cells was partially abolished by indomethacin, indicating that this depression was a PGE2 effect. However, supplementing IL-1 beta with indomethacin did not raise the 3H-thymidine incorporation rates above the control levels. It can be concluded that IL-1 beta in itself is unable to induce proliferation in recently isolated cartilage cells. Our results suggest the possible existence of two different receptors for the different IL-1 beta activities. Hence, human articular chondrocytes respond differently to in vitro IL-1 beta exposure at different stages of differentiation.
Verbruggen
G
G
Department of Rheumatology, University Hospital, Ghent, Belgium.
Veys
E M
EM
Malfait
A M
AM
De Clercq
L
L
Van den Bosch
F
F
de Vlam
K
K
D002358:Cartilage, Articular / Q000187:drug effects*; D015232:Dinoprostone / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D008938:Mitosis / Q000502:physiology; D011509:Proteoglycans / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D013462:Sulfur Radioisotopes; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D007375:Interleukin-1; D011509:Proteoglycans; D011994:Recombinant Proteins; D013462:Sulfur Radioisotopes; D014316:Tritium; D015232:Dinoprostone; D013936:Thymidine