Agren U M, Tammi M, Tammi R
Department of Anatomy, University of Kuopio, Finland.
J Cell Physiol. 1995 Aug;164(2):240-8. doi: 10.1002/jcp.1041640204.
We studied the influence of hydrocortisone (HC) on hyaluronan (HA) metabolism in explants of human skin, a model retaining normal three-dimensional architecture of dermal connective tissue and dynamic growth and stratification of epidermal keratinocytes. The synthesis of hyaluronan and proteoglycans (PGs), and DNA, were determined with 3H-glucosamine and 3H-thymidine labelings, respectively. The total content and histological distribution of hyaluronan was studied utilizing a biotinylated aggrecan-link protein complex. A low concentration of HC (10(-9) M) stimulated the incorporation of 3H-glucosamine into hyaluronan in epidermis by 23% and reduced the disappearance rate of hyaluronan by 25% in chase experiments, resulting in a 74% increase in total hyaluronan (per epidermal dry weight) after a 5-day culture in 10(-9) M HC. On the other hand, a high concentration of HC (10(-5) M) reduced both synthesis (-42%) and degradation (-46%) of epidermal hyaluronan during 24 h labeling and chase periods. The cumulative effect of a 5-day treatment was a 24% decrease of total epidermal hyaluronan. The high dose (10(-5) M) also reduced keratinocyte DNA synthesis and epidermal thickness. In dermis, only the high (10(-5) M) concentration of HC was effective, inhibiting the incorporation of 3H-glucosamine into hyaluronan by 28%. No significant influences on total hyaluronan content or the disappearance rate of hyaluronan in dermal tissue was found. All HC concentrations lacked significant effects on newly synthesized PGs in epidermal and dermal tissues, but reduced the labeled PGs diffusing into culture medium. A low physiological concentration of HC thus maintains active synthesis and high concentration of hyaluronan in epidermal tissue, while high pharmacological doses of HC slows hyaluronan turnover and reduces its content in epidermis, an effect correlated with enhanced terminal differentiation, reduced proliferation rate and reduced number of vital keratinocyte layers.
我们研究了氢化可的松（HC）对人皮肤外植体中透明质酸（HA）代谢的影响，该模型保留了真皮结缔组织正常的三维结构以及表皮角质形成细胞的动态生长和分层。分别用³H-葡糖胺和³H-胸腺嘧啶核苷标记法测定透明质酸和蛋白聚糖（PGs）以及DNA的合成。利用生物素化的聚集蛋白聚糖-连接蛋白复合物研究透明质酸的总含量和组织学分布。低浓度的HC（10⁻⁹ M）在追踪实验中使表皮中³H-葡糖胺掺入透明质酸的量增加了23%，并使透明质酸的消失率降低了25%，在10⁻⁹ M HC中培养5天后，透明质酸总量（每表皮干重）增加了74%。另一方面，高浓度的HC（10⁻⁵ M）在24小时标记和追踪期间降低了表皮透明质酸的合成（-42%）和降解（-46%）。5天治疗的累积效应是表皮透明质酸总量减少了24%。高剂量（10⁻⁵ M）还降低了角质形成细胞DNA合成和表皮厚度。在真皮中，只有高浓度（10⁻⁵ M）的HC有效，抑制³H-葡糖胺掺入透明质酸达28%。未发现对真皮组织中透明质酸的总含量或消失率有显著影响。所有HC浓度对表皮和真皮组织中新合成的PGs均无显著影响，但减少了扩散到培养基中的标记PGs。因此，低生理浓度的HC可维持表皮组织中透明质酸的活跃合成和高浓度，而高药理剂量的HC减缓了透明质酸的周转并降低了其在表皮中的含量，这种效应与终末分化增强、增殖率降低和存活角质形成细胞层数减少相关。
