Glucocorticoids alter the ratio of type III type I collagen synthesis by mouse dermal fibroblasts

The Effect of Topical Corticosteroid Time of Application on Fibroblast and Type III Collagen Expression in Oryctolagus cuniculus with Deep Dermal Burn Wound (As an Indicator for the Best Time to Start Topical Corticosteroid Application in Preventing Hypertrophic Scar)

Background: Hypertrophic scar is an abnormal scar that causes physical deteriorations, psychological problems, and aesthetic issues. An excessive number of fibroblasts and collagen III expressions are histopathology indicators for the hypertrophic scar. The role of topical corticosteroids in suppressing inflammation and hypergranulation had widely demonstrated in previous studies. However, there is no study related to the application of topical corticosteroids as prevention of hypertrophic scars from burn wound found. Hence, this study aimed to examine the evidence of the effects of corticosteroid topical in decreasing the number of fibroblasts and type III collagen expression and the best time to start its application in preventing hypertrophic scars. Methods: This randomized experimental post-test only study involved 54 deep dermal burn wounds on the ventral ear of female Oryctolagus cuniculus that distributed into three groups based on the healing phases. Each group consisted of treatments and controls. Corticosteroid topical application on the first treatment group (inflammatory phase group), the second group (proliferation phase group), and the third group (remodelling phase group) was started on day 3, on day 10, and day 21, respectively. Specimens taken on day 35. Haematoxylin-Eosin and Immunohistochemically staining performed to measure the number of fibroblasts and type III collagen and to observe the epithelization and inflammation process. Results: The number of fibroblasts significantly decreased in the second treatment group (p =0.001) and followed by the first group (p = 0.016), but no significant decrease found in the third group (p = 0.430). The type III collagen decreased significantly in the second treatment group (p = 0.000) and followed by the third group (p = 0.019), but no significant decrease found in the first group. There was no statistically different number of fibroblast and type III collagen discovered between the controls. Complete epithelization found in all groups. Also, no ongoing inflammation found in all groups.  Conclusion : Topical corticosteroids on deep dermal burn wound revealed to be effective in reducing the number of fibroblasts and type III collagen with no healing disruption. The proliferation phase found to be the best time to start the application of topical corticosteroids.

Influence of aldosterone on collagen synthesis and proliferation of rat cardiac fibroblasts

1. Previous in vivo studies in men and experimental animal models have shown that hyperaldosteronemia is correlated with cardiac fibrosis due to increased total collagen synthesis. As yet, it is unclear whether aldosterone has direct pro-fibrogenic effect on cardiac fibroblasts, the fibrogenic effector cell in the myocardium, and if so which procollagens specifically are synthesized at higher rates. 2. The present study aims at establishing whether de novo collagen synthesis by cardiac fibroblasts is enhanced following exposure for 2x24 h to pharmacological (10(-7) - 10(-8) M), near-physiological (10(-9) M) or physiological (10(-10) - 10(-11) M) aldosterone concentrations. During the last 24 h, cells were metabolically labelled with [35S]-methionine/[35S]-cysteine. Labelled procollagens were immunoprecipitated quantitatively using antibodies against specific procollagens. Contrary to expectations, 10(-7) M aldosterone inhibited significantly de novo synthesis of procollagens type I and IV (-35% and -42%, respectively). For procollagen type III, only a tendency towards inhibition was observed. At lower concentrations of aldosterone (10(-8) - 10(-10) M), synthesis of procollagens type I, III or IV was unaffected. 3. Cellular DNA synthesis under influence of aldosterone was evaluated by measuring BrdU incorporation. Cells were treated with aldosterone, while BrdU was added during the last 16 h of treatment. Aldosterone had no demonstrable effect on cellular proliferation. 4. Reverse transcription-polymerase chain reaction (RT - PCR) clearly demonstrated the presence of mineralocorticoid receptor mRNA in cardiac fibroblasts. 5. In spite of the expression of the mineralocorticoid receptor by cultured cardiac fibroblasts, the pro-fibrogenic effect of aldosterone as observed in vivo, is not likely to be due to a direct effect of this hormone in cardiac fibroblasts.

Basement membrane changes in psoriatic patients on long-term topical corticosteroid therapy

It has been observed that the beneficial anti-inflammatory effects of topical steroids in psoriasis are counteracted by increasing instability of the disease, with rebound phenomena associated with the cessation of these drugs. We report the occurrence of multi-layered fragmentation and disorganization of the basal laminae in active, untreated psoriatic lesions, resolving and uninvolved, inadvertently steroid-treated psoriatic skin, as well as in a variety of non-psoriatic dermatoses treated with fluorinated topical steroids for prolonged periods. These changes, which were associated with a moderate to severe loss of dermal collagen, were not found in untreated and treated psoriatic controls, with or without concomitant alpha 1-antitrypsin deficiency, who had not received steroids, suggesting that they were probably the consequence of prolonged fluorinated steroid use. This conclusion is supported by the observation that the largest number of layers (10-15) of fragmented basal laminae was noted in the patients who had received fluorinated steroids for 6 years or more, while those on 4 years or less of fluorinated steroid therapy exhibited only three to seven layers of fragmented basal laminae. In psoriatic lesions, the fragmentation of the basal lamina was associated with the presence of basal keratinocyte herniations (BKH), the frequency of which has been shown to parallel clinical psoriatic activity. The persistence of these electron-microscopic markers of psoriatic activity (i.e. BKH) in psoriatic plaques treated with prolonged fluorinated steroids suggests that loss of integrity of the basement membrane, as indicated by the presence of multi-layered fragmentation of the basal lamina, may account for the instability of the psoriatic lesions treated with prolonged topical fluorinated steroids.

Glucocorticoids change the ratio of type III to type I procollagen extracellularly

Rat skin fibroblasts were treated with dexamethasone and labeled with radioactive proline for 2 hours. Intracellular and extracellular procollagens were immunoprecipitated with monospecific polyclonal antibodies. Both intracellular and extracellular types I and III procollagen were decreased coordinately by glucocorticoid treatment. The ratio of type III to type I procollagen was the same for control and dexamethasone-treated cell cultures. However, when rat skin fibroblasts were prelabeled with radioactive proline and chased in the presence of unlabeled proline the ratio of type III to type I extracellular procollagens remained constant in the glucocorticoid-treated cells and increased in control fibroblasts.

Monoamine oxidases A and B are differentially regulated by glucocorticoids and "aging" in human skin fibroblasts

Two forms of monoamine oxidase (MAO A and MAO B) exist which, although similar in a number of properties, can be distinguished on the basis of their substrate specificity, inhibitor sensitivity, kinetic parameters, and protein structure. These properties were used to study the molecular mechanism(s) by which glucocorticoid hormones and "aging," known to alter MAO activity in vivo, regulated the expression of MAO A and MAO B in cultured human skin fibroblasts. The addition of dexamethasone or hydrocortisone to cultures resulted in a dose- and time-dependent increase in total MAO activity, whereas the removal of hormone from cultures resulted in a time-dependent decrease in activity toward control levels. The response to dexamethasone was affected by culture conditions such as serum concentration, feeding frequency, and cellular "age." Cellular aging, in the absence of hormone, also resulted in increased levels of total MAO activity. The effects of hormones and aging on total MAO activity appeared to be selective for MAO A. The 6- to 14-fold increases in total activity were paralleled by similar increases in the activity and amount of active MAO A but less than 2- to 3-fold increases in the activity and amount of MAO B. Altered synthesis or degradation of the active enzyme appeared to account for the effects of hormones, aging, and various culture conditions on MAO activity. Inhibitor sensitivity, substrate affinity, electrophoretic mobility, and molecular turnover number of either form of the enzyme were not altered during dexamethasone treatment or during cellular aging. However, rates of active MAO synthesis were affected by hormone treatment and feeding frequency, rates of active MAO degradation by serum concentration, and rates of active MAO synthesis or degradation by aging. In summary, we have shown that glucocorticoids and cellular aging selectively affect the amount of MAO A at the level of active enzyme synthesis or degradation. Further, our finding that the expression of the two forms of MAO in human fibroblasts can be independently regulated supports the growing evidence that MAO A and MAO B are separate molecular entities.

Modulation of glucocorticoid receptor activity by cyclic nucleotides and its implications on the regulation of human skin fibroblast growth and protein synthesis

The modulation of glucocorticoid receptor activity by cyclic nucleotides was studied in cultured human skin fibroblasts. The receptors appeared to be activated in the presence of dibutyryl-cAMP and inactivated by dibutyryl-cGMP. Significantly, the cGMP content of the fibroblasts increased during cell growth, with a concomitant decrease in the glucocorticoid receptor activity, while when the cells reached early confluency the decrease in cGMP content was accompanied by an increase in cAMP and increased activity of the glucocorticoid receptors. In addition, cortisol induced (2'-5')oligoadenylate synthetase in these cells and raised the cellular (2'-5')oligoadenylate concentrations. This resulted in a decrease in both DNA and protein synthesis activity in the cells, a response which correlated with the (2'-5')oligoadenylate concentration. The combination of cortisol and dibutyryl-cAMP had a synergetic stimulatory effect on the (2'-5')oligoadenylate concentration and a synergetic inhibitory effect on protein synthesis. In conclusion, it is demonstrated here that cyclic nucleotides can modulate glucocorticoid receptor activity in cultured human skin fibroblasts, and thus these compounds may indirectly affect cellular metabolism by regulating the cellular responses to glucocorticoids.

The contractility of fibroblasts in a collagen lattice is reduced by corticosteroids

Normal human and rat skin fibroblasts, incorporated into a three-dimensional collagen lattice, were assayed for their ability to contract collagen fibrils. This capacity is inhibited in a dose-dependent fashion by both dexamethasone and hydrocortisone. The inhibition is reversed when the corticosteroids are removed from the culture medium, but while the effect of hydrocortisone is almost entirely reversible, that of dexamethasone is not.

Relationship of cell growth to collagen synthesis in glucocorticoid treated A/J and C57BL6/J neonatal mouse dermal fibroblasts

Primary cultures of neonatal dermal fibroblasts from two strains of mice (A/J and C57BL6/J) were utilized as an in vitro system to investigate the effects of glucocorticoids on cell growth and collagen synthesis. Protein and DNA synthesis were lower in untreated (control) A/J fibroblasts than in C57BL6/J fibroblasts. Treatment with glucocorticoids for 4 days resulted in dose-dependent inhibition of [3H]thymidine incorporation into DNA and a reduction in collagen synthesis. Collagen synthesis was differentially more susceptible to glucocorticoids than was total protein synthesis. Neonatal dermal fibroblasts obtained from A/J mice were more sensitive to glucocorticoids than were cells from C57BL6/J mice. Reduction in collagen production by anti-inflammatory steroids in this system may be related to adverse effects observed in vivo following treatment with these steroids.