Stimulation by hydrocortisone of the rate of collagen synthesis in cultured fibroblasts

Age differences in the effect of hydrocortisone on the synthesis of insoluble elastin in aortic tissue of growing chicks

Glucocorticoids have been shown by others to increase the synthesis of elastin both in aortic tissue of embryo chicks and in cells derived from fetal ligamentum nuchae. This report describes the effects of hydrocortisone on the production of elastin in aortic tissue of developing chick embryos and chicks. While the effect of hydrocortisone on elastin synthesis is stimulatory in the 14 day chick embryo and the day-old chick, the same dose of this glucocorticoid has no effect on elastin production in the 7 day old chick and significantly inhibits synthesis of elastin in the 14 day old chick. These age-related alterations in elastin production in response to hydrocortisone cannot be attributed to an effect of the steroid on the pool size of the radioactively labelled amino acid used to measure elastin synthesis.

Collagen synthesis and degradation in acutely damaged mouse lung tissue following treatment with prednisolone

Corticosteroids are widely used to treat patients with acute lung damage. Recent work has shown that the administration of 30 mg/kg prednisolone to mice, twice daily on days 1-5 after the induction of lung damage with butylated hydroxytoluene (BHT), results in the development of a more severe fibrotic lesion [J.P. Kehrer, A.J.P. Klein-Szanto, E. M. B. Sorensen, R. Pearlman and M. H. Rosner, Am. Rev. resp. Dis. 130, 256 (1984)]. In the present study, the rate of collagen synthesis in lung tissue from BHT-saline-treated mice was greater than that in lung tissue from oil-treated controls at all days examined. During prednisolone treatment, the rate of pulmonary collagen synthesis was significantly less in tissue from BHT-prednisolone-treated mice compared to BHT-saline controls. Two days after steroid treatment was stopped (day 7 after BHT), there was a significant increase in the rate of collagen synthesis in lung tissue from BHT-prednisolone-treated mice compared to tissue from both BHT- and oil-treated controls. This increase reached a maximum on day 11 and persisted to day 14 after BHT. The rate of pulmonary non-collagen protein synthesis was inconsistently increased in response to treatments with BHT and/or prednisolone. There was, therefore, a relatively greater increase in the synthesis of collagen. The percentage of total protein synthesis committed to collagen increased from 2% in oil-treated controls to 5% on day 7 after BHT alone and reached a maximum of 7.1% on day 11 in lung tissue from BHT-prednisolone-treated mice. The percentage of newly synthesized collagen that was degraded in lung tissue from BHT-prednisolone-treated mice was significantly lower than BHT-saline on days 7 and 11, and lower than oil-prednisolone on day 14. These results show that collagen synthesis was decreased in BHT-damaged mouse lung tissue during short-term, high-dose steroid therapy. There was, however, an increase in collagen synthesis and a decrease in the degradation of newly synthesized collagen after steroid therapy was stopped. These changes in collagen metabolism may contribute to the steroid-induced enhancement of fibrosis seen in BHT-treated mice.

Glucocorticoid regulation of glycosaminoglycan accumulation in murine fibroblasts

The effects of Dexamethasone (Dex) on Glycosaminoglycan (GAG) accumulation were examined in the murine fibroblast line C3H/10T1/2. Confluent cultures were treated with the hormone and then labelled with either [3H]acetate or [3H]glucosamine and analyzed for [3H]GAG content. Dex could inhibit the accumulation of [3H]GAG in a dose dependent manner with a half maximal response achieved at approximately 5nM and a maximal response at approximately 100nM. Higher concentrations failed to influence precursor incorporation further. The response was seen after 6 hours of hormone exposure and was nearly maximal by 10 hours. The incorporation of [3H]leucine into protein was unaffected by Dex treatment. 11 alpha hydrocortisone, an inactive steroid, failed to elicit a cellular response. Thus it appears that glucocorticoids regulate GAG accumulation in a rodent fibroblast line as they do in primary human skin fibroblast cultures.

Glucocorticoids stimulate collagen and noncollagen protein synthesis in cultured vascular smooth muscle cells

The effect of glucocorticoids on collagen synthesis was examined in cultured bovine aortic smooth muscle (BASM) cells. BASM cells treated with 0.1 microM dexamethasone during their proliferative phase (11 d) were labeled with [3H]proline for 24 h, and the acid-precipitable material was incubated with bacterial collagenase. Dexamethasone produced an approximate twofold increase in the incorporation of proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP) in the cell layer and medium. The stimulation was present in both primary mass cultures and cloned BASM. An increase in CDP and NCP was detected at 0.1 nM, while maximal stimulation occurred at 0.1 microM. Only cells exposed to dexamethasone during their log phase of growth (1-6 d after plating) showed the increase in CDP and NCP when labeled 11 d after plating. The stimulatory effect was observed in BASM cells treated with the natural bovine glucocorticoid, cortisol, dexamethasone, and testosterone, but was absent in cells treated with aldosterone, corticosterone, cholesterol, 17 beta-estradiol, and progesterone. The increase in CDP and NCP was absent in cells treated with the inactive glucocorticoid, epicortisol, and totally abolished by the antagonist, 17 alpha-hydroxyprogesterone, suggesting that the response was mediated by specific cytoplasmic glucocorticoid receptors. Dexamethasone-treated BASM cells showed a 4.5-fold increase in the specific activity of intracellular proline, which was the result of a twofold increase in the uptake of proline and depletion of the total proline pool. After normalizing for specific activity, dexamethasone produced a 2.4- and 2.8-fold increase in the rate of collagen and NCP synthesis, respectively. Cells treated with dexamethasone secreted 1.7-fold more collagen protein in 24 h compared to control cultures. The BASM cells secreted 70% Type I and 30% Type III collagen into the media as assessed by two-dimensional gel electrophoresis. The ratio of these two types was not altered by dexamethasone. The results of the present study demonstrate that glucocorticoids can act directly on vascular smooth muscle cells to increase the synthesis and secretion of collagen and NCP.

Cortisol decreases the cellular concentration of translatable procollagen mRNA species in cultured human skin fibroblasts

The effect of cortisol on the cellular concentration of translatable procollagen mRNAs was studied in cultured human skin fibroblasts. Cortisol selectively decreased the amount of procollagen mRNAs, in comparison to the total mRNA activity, when the cells were grown in enriched medium conditions, i.e., with 10% newborn calf serum. The selective decrease was first observed after 6 h exposure to 1 microM cortisol. In depleted medium conditions, i.e., with 2% newborn calf serum, the initial response was a stimulatory one, followed after about 12 h by a decrease in the procollagen mRNA activity. The results suggest that the selective inhibitory effect of cortisol on the cellular concentration of translatable procollagen mRNA species needs an optimal serum concentration. Furthermore, the results give support to the hypothesis that the decrease in the procollagen mRNA concentration after cortisol administration is a secondary response, preceded by the induction of some intracellular regulation system.

Steroid-induced dermal atrophy: effects of glucocorticosteroids on collagen metabolism in human skin fibroblast cultures

Collagen production by human skin fibroblast cultures was studied by incubation with [3H] proline and several glucocorticosteroids known to produce dermal atrophy in vivo. Collagen production was measured as formation of [3H]hydroxyproline or collagenase-digestible 3H-polypeptides, and the values were corrected for changes in cell number in the same cultures. The steroids, in a wide concentration range, failed to elicit any consistent alterations in collagen production. Review of the literature dealing with corticosteroid-induced changes in collagen production by human skin fibroblasts indicate conflicting results even under apparently similar incubation conditions. Consequently, no unifying hypothesis for steroid-induced dermal atrophy can be developed presently based on the in vitro data.

Differential effects of hydrocortisone on both growth and collagen metabolism of human fibroblasts from normal and keloid tissue

Cultured fibroblasts isolated from normal and keloid tissue do not differ in their growth characteristics or in the rate of collagen synthesis under routine culture conditions. The addition of hydrocortisone to the culture media results in significant differences in both growth and collagen synthesis between these cell types. Collagen synthesis is inhibited 60% in normal cultures by hydrocortisone (0,5 micrograms/ml) and the population size at which density-dependent growth inhibition is achieved is increased. Keloid-derived fibroblasts grow to a lower maximum density in the presence of hydrocortisone, while their rate of collagen synthesis is not significantly reduced. The rate of non-collagen protein synthesis is increased significantly by hydrocortisone in both cell types. Comparison of normal and keloid-derived cultures obtained from a single individual suggests that the keloid phenotype with respect to both growth and collagen synthesis is restricted to the fibroblasts isolated from the keloid nodule.