Differential response of articular cartilage from young growing and mature old mice to IL-1 and TGF-β

Osteoarthritic lesions are observed in temporomandibular joint cartilage of ICR mice aged 7 months and older, accompanied by reduced proliferation and matrix synthesis. Transforming growth factor-β (TGF-β), is a multifactorial growth factor affecting matrix synthesis and cell proliferation in bone and cartilage, whereas interleukin-1 (IL-1) is involved in cartilage degradation. In order to establish the repair capacity of cartilage in aging, the response of cartilage from young and old animals to TGF-β and IL-1 was studied. Mandibular condyles from young (1-month-old) and old (18-month-old) mice were cultured for up to 72 h in medium supplemented with TGF-β1 or IL-1α. TGF-β increased protein (+9.26%) and DNA (+36.0%) contents in young animals and DNA content (+19.49%) in old animals. Incorporations of [3H]thymidine and [35S]sulfate were enhanced in young (+254% and +116%, respectively) and in old (+22.6% and +6.88%, respectively) and animals and activity of alkaline phosphatase was induced in old animals. Treatment with IL-1 resulted in reduced DNA content in young (−35.76%) and old (−33.33%) animals, but acid phosphatase activity was induced in old animals. It is concluded that TGF-β can induce anabolic activity even in cartilage from old animals indicating repair response in articular cartilage in aging.