THE EFFECT OF THYROID HORMONE ON GLYCOSAMINOGLYCAN ACCUMULATION IN HUMAN SKIN FIBROBLASTS

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Abstract
Because the dermis of myxedematous humans is known to accumulate increased amounts of qlycosaminoglycan (GAG), we were prompted to study the effects of thyroid hormone depletion in vitro. Human skin fibroblasts were grown to confluence in medium containing 10% fetal calf serum (FCS). Some cultures were shifted to a medium containing FCS depleted of thyroid hormone (D-FCS) or to a D-FCS medium to which 10-7 M triiodothyronine (T3) was added (D-FCS + T3). Cultures were then labeled for 16 h with [3H]-acetate, harvested and combined with the media. After pronase digestion, the non-trichloroacetic acid precipitable, non-dialysable material was digested with streptomyces hyaluronidase followed by chondroitinase ABC. Digestable material was separated by G-50 Sephadex column chromatography. The cultures incubated in media containing D-FCS accumulated 2.8-fold more hyaluronic acid and 2.1-fold more chondroitin sulfate than did sister cultures incubated in the presence of D-FCS + T3. The addition of T3 to the D-FCS reduced the amounts of GAG accumulated nearly to the levels observed in cultures grown in FCS. The data indicate that thyroid hormone exerts an inhibitory effect on GAG accumulation in human skin fibroblasts. This model offers the opportunity to study thyroid hormone action in vitro using an easily accessible human tissue.