TYPE-II COLLAGEN AND TGF-BETA-S IN DEVELOPING AND AGING PORCINE MANDIBULAR CONDYLAR CARTILAGE - IMMUNOHISTOCHEMICAL STUDIES

Transforming growth factor-betas (TGF-Ps) have been associated with th e development and maintenance of articular cartilage. However, no stud ies have addressed their role in the postnatal development of mandibul ar condylar cartilage. This investigation represents the first immunoh istochemical characterization of TGF-P isoforms and type II collagen i n porcine mandibular condylar cartilage from various age groups. Furth ermore, it is the first description of possible age-related changes in the expression of these proteins during postnatal development of this tissue. Condylar cartilage was dissected from freshly harvested tempo romandibular joints of newborn, 6-, 12-, 24-, and 36-month-old farm sw ine. TGF-beta 1, TGF-beta 2, TGF-beta 3, and type II collagen were loc alized via standard immunohistochemical procedures. An immunoblot tech nique was employed to compare the relative amount of each protein pres ent in the various age groups. Immunoreactivity was detected in mandib ular condylar cartilage for all three isoforms of TGF-beta and for Typ e II collagen. All age groups demonstrated some evidence of immunostai ning, primarily in the cytoplasm of cells from most zones of the carti lage. Immunoblot results indicated that TGF-beta isoforms had individu alized patterns of expression. When newborn protein levels were taken as the baseline, TGF-beta 1 demonstrated a significant increase at age s 24 and 36 months. TGF-beta 2 significantly increased at 6, 12, 24, a nd 36 months (peak levels at 24 months; similar levels at 6, 12, and 3 6 months), whereas TGF-beta 3 remained stable at all ages. Type II col lagen demonstrated increases that paralleled the increased levels of T GF-beta 1 and TGF-beta 2 at 24 and 36 months.