Effects of glucocorticosteroids on primary human skin fibroblasts. II. Effects on total protein and collagen biosynthesis by confluent cell cultures

The Effects of Steroids on Survival of Mouse and Human Tympanic Membrane Fibroblasts

OBJECTIVE

Tympanic membrane (TM) fibroblast cytotoxicity of quinolone ear drops is enhanced by dexamethasone and fluocinolone. Hydrocortisone has not been evaluated. We aimed to assess the effects of these 3 steroids on mouse and human TM fibroblast survival.

STUDY DESIGN

In vitro.

SETTING

Academic laboratory.

SUBJECTS AND METHODS

Mouse and human TM fibroblasts were exposed to hydrocortisone, dexamethasone, or fluocinolone at concentrations in commercial ear drops (1%, 0.1%, or 0.025%, respectively) and at steroid potency equivalents (1%, 0.033%, or 0.0033%, respectively), or dilute ethanol (control), twice within 24 hours or 4 times within 48 hours for 2 hours each time. Cells were observed with phase-contrast microscopy until the cytotoxicity assay was performed.

RESULTS

Mouse and human TM fibroblasts treated with any of the steroids had lower survival after 24 and 48 hours compared to control (all P < .0001). After 24 hours, viability of mouse fibroblasts treated with the steroids was not different (P > .05), while treatment with hydrocortisone decreased human TM fibroblast viability (P < .0001). After 48 hours, at concentrations found in ear drops and at equivalent steroid potency, dexamethasone and fluocinolone had similar survival in mouse and human fibroblasts (all P > .05), but hydrocortisone had lower survival in both mouse (P = .02 and P < .0001) and human (P < .0001) fibroblasts. Phase-contrast images mirrored the cytotoxicity findings.

CONCLUSION

Steroids found in commercial ear drops reduce survival of mouse and human TM fibroblasts. Hydrocortisone appears to be more cytotoxic than the more potent steroids, dexamethasone and fluocinolone. These findings should be considered when assessing clinical outcomes of ototopical preparations.

Normal and keloid fibroblasts are differentially influenced by IFN-γ and triamcinolone as well as by their combination

Impaired wound healing as well as imbalanced cell proliferation and extracellular matrix synthesis and degeneration can cause aberrant scarring. The most severe impacts of such scarring on patients' lives are stigmatization and physical restriction. Although, a broad variety of combinatorial approaches with, e.g., glucocorticoids, chemotherapeutics, and immunomodulators are used, there is still a high recurrence rate of keloids. The aim of this study was to investigate which influence interferon γ (IFN-γ, 1.000-10.000 IU/mL) and/or triamcinolone acetonide (TA, 1 μg/mL) have on proliferation, cell viability, collagen type I synthesis, and cytokine secretion in healthy and keloid fibroblasts. It was shown that mono-treatment with IFN-γ or TA for 2 days induced a severe reduction of the proliferative potential in both cell species. The combinatory treatment (IFN-γ plus TA) of keloid fibroblasts enhanced the anti-proliferative effect of the mono-treatments, whereas no additional anti-proliferative effect was observed in normal fibroblasts. Furthermore, we observed that the combinatory treatment regimen reduced the expression of α-smooth muscle actin (α-SMA), an actin isotype contributing to cell-generated mechanical tension, in keloid fibroblasts. In normal fibroblasts, α-SMA was reduced by the mono-treatment with IFN-γ as well as by the combinatory treatment. The analysis of collagen-type I synthesis revealed that TA did not reduce collagen type I synthesis in normal fibroblasts but in keloid fibroblasts. IFN-γ reduced in both cell species the collagen type I synthesis. The combination of TA and IFN-γ intensified the previously observed collagen type I synthesis reduction in keloid fibroblasts. The herein presented data suggest the combinatory application of IFN-γ and TA as a promising therapy concept for keloids.

Evaluation of anti-inflammatory and atrophogenic effects of glucocorticoids on reconstructed human skin

Topical glucocorticoids (GCs) are extensively used in the treatment of inflammatory skin diseases. However, their long-term use is often accompanied by severe and eventually irreversible adverse effects, with atrophy being the most important limitation. Currently, most non-clinical studies involve animal testing, so the results are not always representative of the situation in humans. The aim of this project was to establish an in vitro test protocol for the evaluation of the anti-inflammatory and atrophic potential of topically applied GCs in reconstructed human skin. Initial studies with fibroblasts and keratinocytes confirmed the anti-inflammatory and atrophogenic effects of GCs, as evidenced by decreased cytokine production and collagen mRNA expression. In non-pretreated reconstructed human skin (EpiDermFT™), the topical application of GCs for seven days strongly reduced the secretion of interleukin (IL)-6. GC-induced skin atrophy, known to appear only after prolonged treatment, was not detected by the analysis of epidermal thickness and collagen mRNA expression. However, reproducible epidermal inflammation was established for the first time in reconstructed human skin. Topical treatment with tumour necrosis factor (TNF) increased IL-6 release and strongly reduced epidermal thickness accompanied by severe parakeratosis. GC treatment of reconstructed human skin reduced IL-6 levels and completely resolved parakeratosis, leading to the normalisation of epidermal thickness. These induced inflammatory conditions mimic more closely the clinical situations in which GCs are used, and therefore appear to be more suitable for future investigations for the establishment of a human-based in vitro test protocol for evaluating wanted and unwanted GC effects.

A cytotoxic analysis of antiseptic medication on skin substitutes and autograft

BACKGROUND

There is an increasing demand for the clinical application of human skin substitutes (HSSs) for treating ulcers, burns and surgical wounds. Due to this increasing demand and due to the simultaneous requirement for the administration of topical antiseptic medications, there is a need to determine potential cytotoxic effects of these medications on HSSs compared with autograft skin.

OBJECTIVES

To perform such an evaluation.

METHODS

Two different HSSs were used (autologous reconstructed epidermis on fibroblast-populated human dermis and allogeneic reconstructed epidermis on a fibroblast-populated rat collagen gel) and were compared with conventional full-thickness autograft. Twelve different antiseptics were applied topically to the stratum corneum in vitro for 24 h. The degree of cytotoxicity was analysed as detrimental changes in histology, metabolic activity (MTT assay) and RNA staining of tissue sections.

RESULTS

The antiseptic medications tested showed different degrees of cytotoxicity. Acticoat, Aquacel Ag, Dermacyn, Fucidin, 0.5% silver nitrate solution and chlorhexidine digluconate were not cytotoxic for either HSS or autograft, and can therefore be used as required. Flamazine and zinc oxide cream resulted in moderate cytotoxicity. However, application of Betadine((R)), cerium-silver sulfadiazine cream, silver sulfadiazine cream with 1% acetic acid and Furacine resulted in a substantial decrease in cell viability and a detrimental effect on tissue histology when applied to autograft and especially to HSS.

CONCLUSIONS

Due to the potential cytotoxic effect of some antiseptics on HSS, it is advised that clinicians balance the cytotoxicity of the medication, its antiseptic properties and the severity of colonization in choosing which one to apply.

Autologous full-thickness skin substitute for healing chronic wounds

BACKGROUND

Chronic wounds represent a major problem to our society. Therefore, advanced wound-healing strategies for the treatment of these wounds are expanding into the field of tissue engineering.

OBJECTIVES

To develop a novel tissue-engineered, autologous, full-thickness skin substitute of entirely human origin and to determine its ability to heal chronic wounds.

METHODS

Skin substitutes (fully differentiated epidermis on fibroblast-populated human dermis) were constructed from 3-mm punch biopsies isolated from patients to be treated. Acellular allodermis was used as a dermal matrix. After a prior 5-day vacuum-assisted closure therapy to prepare the wound bed, skin substitutes were applied in a simple one-step surgical procedure to 19 long-standing recalcitrant leg ulcers (14 patients; ulcer duration 0.5-50 years).

RESULTS

The success rate in culturing biopsies was 97%. The skin substitute visibly resembled an autograft. Eleven of the 19 ulcers (size 1-10 cm2) healed within 8 weeks after a single application of the skin substitute. The other eight larger (60-150 cm2) and/or complicated ulcers healed completely (n = 5) or continued to decrease substantially in size (n = 3) after the 8-week follow-up period. Wound healing occurred by direct take of the skin substitute (n = 12) and/or stimulation of granulation tissue/epithelialization (n = 7). Skin substitutes were very well tolerated and pain relief was immediate after application.

CONCLUSIONS

Application of this novel skin substitute provides a promising new therapy for healing chronic wounds resistant to conventional therapies.

Glucocorticoid therapy-induced skin atrophy

Glucocorticoids (GCs) are highly effective for the topical treatment of inflammatory skin diseases. Their long-term use, however, is often accompanied by severe and partially irreversible adverse effects, with atrophy being the most prominent limitation. Progress in the understanding of GC-mediated molecular action as well as some advances in technologies to determine the atrophogenic potential of compounds has been made recently. It is likely that the detailed mechanisms of GC-induced skin atrophy will be discovered and in vitro models for the reliable prediction of atrophy will be established in the foreseeable future. This knowledge will not only facilitate safety profiling of established drugs but will also foster further drug discovery by improving compound characterization processes. New insights into GC modes of action will guide optimization strategies aiming at novel GC receptor ligands with improved effect/side effect profile.

Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure

The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin.

Dexamethasone activates expression of the PDGF-alpha receptor and induces lung fibroblast proliferation

Corticosteroids (CSs) are commonly used for anti-inflammatory therapy in asthma and in interstitial lung diseases. In attempting to understand the mechanisms through which CSs control cell proliferation, we have carried out experiments to test the effects of dexamethasone (Dex) on the growth of lung fibroblasts. Using mouse 3T3 fibroblasts as well as early-passage rat lung fibroblasts (RLFs), we show that the quiescent cells in 1% serum or in serum-free media proliferate significantly in response to the addition of 10(-7) to 10(-9) M Dex. Increases as high as fourfold in cell numbers were recorded for the RLFs after 48 h in culture. A polyclonal antibody to the AB isoform of human platelet-derived growth factor (PDGF) blocked the proliferative response. As expected, the fibroblasts produced primarily PDGF-A chain, and the RLFs exhibited few PDGF-alpha receptors (PDGF-R alpha), the receptor type necessary for binding the AA isoform. Accordingly, we determined that Dex upregulated PDGF-R alpha mRNA and protein. Therefore, we can postulate that Dex-induced fibroblast proliferation is mediated, at least in part, by PDGF-AA, which binds to the PDGF-R alpha.

Immunocytochemical localization of glucocorticoid receptor in rat skin

The aim of the present study was to map immunohistochemically the distribution of the glucocorticoid receptor (GR) in rat skin. Nuclear GR-like immunoreactivity (LI) was found in both epidermis and dermis. In the epidermis, the basal cell layer showed an intense immunoreaction; the lower part of the spinous layer was also labelled. In the dermis, the fibroblasts as well as the sweat glands, sebocytes and adipocytes were GR-immunoreactive (IR). In the root sheath of the hair follicle the staining was most intensive in the outer layer. The endothelial cells comprising the smooth muscle cells of the blood vessels, as well as the arrector pili muscle, showed GR-LI. In the peripheral nerves, the immunoreaction was localized to the nuclei of the Schwann cells and in the perineurial fibroblasts. Mast cells did not show nuclear GR-LI. Based on our immunocytochemical findings that several cell types of the skin are GR-IR, the variable physiological and pharmacological effects of glucocorticoids are easier to understand.

Localization of the glucocorticoid receptor in testis and accessory sexual organs of male rat

Localization of glucocorticoid receptor-like immunoreactivity (GR-LI) was studied in adult rat testis, epididymis, ejaculatory duct, seminal vesicle and prostate by light and electron microscopic immunocytochemistry. In the interstitium of the testis GR-LI was seen in the nuclei of Leydig cells, macrophages, fibroblasts, smooth muscle cells and endothelial cells of blood vessels. Furthermore, GR-LI was observed in zygotene and early pachytene primary spermatocytes of some seminiferous tubules during stages XIII-XIV and I-III of the spermatogenic cycle. Other spermatogenic cells and Sertoli cells were devoid of staining. GR-LI was also found in peritubular myoid cells, fibroblasts and basal cells of the epididymis, vas deferens and prostate. Localization of GR-LI in primary spermatocytes and Leydig cells suggests that glucocorticoids directly affect spermato- and steroidogenesis in the testis. The absence of GR-LI from functional, stromal cells of the male accessory sexual organs suggests that they are not targets for glucocorticoid hormones.

Regulation by glucocorticoids of interferon gamma-induced HLA-DR antigen expression in cultured human orbital fibroblasts

OBJECTIVE

The purpose of this study was to determine whether glucocorticoids can block the induction of HLA-DR antigen expression by interferon gamma in human fibroblasts in culture.

DESIGN AND PATIENTS

Confluent cultures of fibroblasts derived from the orbit or the skin of patients with Graves' ophthalmopathy or from normal subjects were treated with interferon gamma (100 U/ml) without or with graded concentrations of steroids.

MEASUREMENTS

Cultures were analysed for HLA-DR expression using quantitative immunoblotting and indirect immunofluorescence.

RESULTS

Glucocorticoids could block HLA-DR induction in a dose-dependent manner. At 10(-6) mol/l, the steroids dexamethasone and RU 28362 inhibited expression by 70% (P < 0.004) and 56% (P < 0.002) respectively. RU 38486, a glucocorticoid antagonist, could reverse the effect of both glucocorticoids, an action that was also dose dependent. At 10(-5) mol/l, RU 38486 blocked virtually the entire glucocorticoid effect.

CONCLUSIONS

These results suggest that glucocorticoids can regulate HLA-DR induction by interferon gamma at physiological concentrations, an action which is stereospecific and mediated through the glucocorticoid receptor.

Influence of corticosteroids on chemotactic response and collagen metabolism of human skin fibroblasts

Following chronic administration of corticosteroids in vivo, a number of complications occur, which mainly involve the metabolism of connective tissue cells. Therefore, several attempts have been made to develop corticosteroids, which show less pronounced side effects. Fibroblasts were kept in monolayer cultures and were exposed to corticosteroids demonstrating similar anti-inflammatory activity (prednicarbate, desoximetasone). Chemotaxis of fibroblasts was studied over 4 hr, protein and collagen synthesis were estimated using proteinchemical methods and also by dot blot hybridization. Corticosteroids used in a high dosage (10 microM) affected all biosynthetic capacities of the investigated fibroblasts. Protein synthesis and production of collagen types I and III were reduced and a similar decrease of mRNA levels for collagen type I could be found indicating an influence on the pretranslational control. In the same concentrations desoximetasone was much more active than prednicarbate. Fibroblast migration was dosage dependently inhibited from 10(-9) M to 10(-5) M for desoximetasone, while incubation with prednicarbate did not cause a reduction of the chemotactic response at concentrations lower than 10(-7) M. These data suggest that modifications of corticosteroids might result in a dissociation of some of their biological activities and can specifically influence their effects on biosynthetic capacities of fibroblasts.

Glucocorticoid regulation of glycosaminoglycan synthesis in cultured human skin fibroblasts: evidence for a receptor-mediated mechanism involving effects on specific de novo protein synthesis

Human skin fibroblast cultures synthesize and accumulate glycosaminoglycan (GAG). This laboratory has reported recently that the synthetic rate of hyaluronate (HA), the most abundant GAG produced by these cells, is inhibited by glucocorticoids. The purpose of these studies was to characterize further that hormonal response. Effects of potent glucocorticoid agonists dexamethasone (Dex) and RU28362 on GAG synthesis were studied. Both steroids inhibited [3H]GAG synthesis when added 24 hours before labeling with [3H]acetate. RU28362 inhibited HA synthesis by 58% and Dex by 60%. The half-maximal effect for each was achieved at a concentration of 0.5 nmol/L and maximal effects at 10 nmol/L. The recently described glucocorticoid antagonist RU38486 failed to alter [3H]GAG synthesis at concentrations up to 1,000 nmol/L. However, this compound did block the inhibition of the agonists. At concentrations of RU28362 and Dex that maximally inhibited [3H]GAG synthesis (10 nmol/L), RU38486 attenuated the glucocorticoid effect in a dose-dependent manner, with half-maximal inhibition at 5 nmol/L and maximal inhibition at 100 nmol/L. The antagonist blocked as much as approximately 80% of the Dex inhibition and approximately 70% of the RU28362 inhibition. Cycloheximide (25 micrograms/mL) inhibited [3H]HA synthesis by 55% within four hours of its addition to the culture. When cultures were pretreated with cycloheximide without or with Dex (100 nmol/L) for three hours and then treated with actinomycin D (2 micrograms/mL) followed by [3H]acetate labeling, Dex pretreated cultures synthesized 33% less [3H]GAG, implying that Dex had decreased the abundance of a translatable mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid and glucocorticoid hormone regulation of specific protein abundance in cultured human skin fibroblasts

Effects of 3,3',5-triiodo-L-thyronine (T3) and dexamethasone (Dex) on the abundance of proteins resolvable by two-dimensional gel electrophoresis were examined in cultured human skin fibroblasts. Confluent cultures were incubated in medium supplemented with thyroidectomized calf serum and were treated with either T3 (100 nM), Dex (100 nM) or both hormones for 2 days and then labelled with [3H]leucine for 1 day. Most of the greater than 100 resolvable radiolabelled proteins were unaffected by hormone treatment. However, both hormones could increase or decrease the abundance of a limited number (approximately 10) of specific proteins. Some of these affected proteins appear to be coregulated. This result is consistent with effects demonstrated previously in pituitary adenoma cultures and suggests that both hormones regulate protein metabolism in human fibroblasts. This may be an ideal model for studying the nature of resistance to thyroid and glucocorticoid hormones.

Cutaneous tissue repair: practical implications of current knowledge. II

This article reviews the scientific basis for the certain factors that delay wound repair in the clinical setting. A brief history of wound healing is given, followed by a discussion of endogenous local factors (bacterial infection, hypoxia, foreign body, and desiccation) and endogenous systemic factors (nutritional deficiencies, aging, coagulation disorders, and the Ehlers-Danlos syndromes) associated with poor wound repair. Also reviewed are the mechanisms by which exogenously administered agents (glucocorticoids, antineoplastic agents, and anticoagulants) may delay healing. Commonly used topical antimicrobials, their spectrum of activity, and evidence of effects on wound healing are examined. Finally, properties of commercially available wound coverings and wound care in the future are discussed.

Dexamethasone regulation of glycosaminoglycan synthesis in cultured human skin fibroblasts. Similar effects of glucocorticoid and thyroid hormones

The effects of dexamethasone on glycosaminoglycan accumulation were examined in confluent human skin fibroblasts in vitro. The glucocorticoid consistently inhibited the incorporation of either [3H]acetate or [3H]glucosamine into hyaluronate when added to culture medium 72 h before harvest. This effect was half-maximal at approximately 1 nM and maximal at 5-10 nM. Inhibition occurred within 5 h of hormone addition and was near maximal by 25 h. 11 alpha-hydrocortisone (10 nM), deoxycorticosterone (10 nM), and progesterone (100 nM) failed to inhibit this accumulation; however, progesterone (2 microM), a known glucocorticoid antagonist at high concentration, could attenuate the response to dexamethasone by 57%. Cultures were pulse-labeled and then chase incubated for up to 68 h. No difference in the rate of [3H]hyaluronate degradation could be demonstrated in steroid-treated cultures. Triiodothyronine (T3) can also inhibit synthesis of hyaluronate in fibroblasts (Smith, T. J., Y. Murata, A. L. Horwitz, L. Philipson, and S. Refetoff, 1982, J. Clin. Invest., 70:1066-1073). Both T3 and dexamethasone could inhibit glycosaminoglycan accumulation in a dose-dependent manner. Maximal T3 effects were achieved at 1 nM and those of dexamethasone at 10 nM. Saturating concentrations of T3 and dexamethasone added alone inhibited [3H]hyaluronate by 54 and 49%, respectively. When both hormones were added, accumulation was inhibited by 84%. Dexamethasone inhibits [3H]hyaluronate accumulation in a time, dose-dependent, and stereo-specific manner. The rate of glycosaminoglycan degradation was unaffected, and thus, the steroid inhibited the rate of macromolecular synthesis. This effect was likely mediated through glucocorticoid receptors. Hyaluronate synthesis in skin fibroblasts appears to be regulated by both glucocorticoids and T3 through different pathways.

Effect of dexamethasone on nuclear envelope nucleoside triphosphatase in fibroblasts 3T3 and melanoma cells MMLI

Glucocorticoids are known to influence DNA and RNA synthesis in skin fibroblasts. In a novel approach to study this effect, we investigated the influence of the hormone analogue dexamethasone on the activity of nuclear envelope-associated nucleoside triphosphatase (NTPase) in intact cell systems (3T3 fibroblasts and MMLI melanoma cells). The NTPase is thought to be responsible for regulation of nucleocytoplasmic transport of mRNA. [3H]Dexamethasone was found to bind to nuclear ghosts at a density comparable with that of nuclear pores in this cellular fraction. Incubation of the cells for 48 h in the presence of different concentrations of dexamethasone resulted in a marked decrease of NTPase activity. Already concentrations as low as 0.1 ng/ml (3T3) or 1 ng/ml (MMLI) reduced the NTPase activity by approximately 50%. These results suggest that nuclear envelope NTPase is a site at which glucocorticoids regulate gene expression.

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.

Effect of glucocorticoids on glycosaminoglycan metabolism in cultured human skin fibroblasts

Human skin fibroblasts were exposed to 3 anti-inflammatory steroids in order to study their effects on the glycosaminoglycan metabolism. The potent glucocorticoids, fluocinolone acetonide and budesonide, even at low concentrations strongly reduced the accumulation of hyaluronic acid and sulfated glycosaminoglycans in the medium, at the cell surface, and in the cells. Hydrocortisone had considerably less effect. The 3 compartments were not influenced to the same extent and the least inhibition was noted in the cell surface pool. Dermatan sulfate was decreased to the same relative extent in all 3 compartments, while hyaluronic acid and heparan sulfate were specifically retained at the cell surface, explaining why this compartment was less affected than the others. Dermatan sulfate was studied in more detail regarding effects on its copolymeric structure. Glucocorticoid treatment changed the uronosyl composition of the polysaccharides so that a relative decrease of glucuronic acid residues and a relative increase of iduronic acid residues were noted. This change was most evident in dermatan sulfate of the medium and of the cell surface. Thus, glucocorticoid treatment not only reduces the quantity of various glycosaminoglycans but also changes the distribution, the relative proportion, and the structure of connective tissue proteoglycans. These effects probably contribute to the development of skin atrophy, which often is observed after long-term treatment with potent glucocorticoids.

Glucocorticoids and cultured human skin cells: specific intracellular binding and structure-activity relationships

Cytosol fractions of both cultured human skin fibroblasts and epidermal keratinocytes contain macromolecules that bind glucocorticoids with high affinity. Using the cytosol of cultured keratinocytes good correlation has been found between the displacement of radiolabelled glucocorticoids (3H-hydrocortisone, 3H-dexamethasone and 3H-triamcinolone acetonide) by a variety of glucocorticoids and the clinical efficacy. The structure-binding relationship studies revealed the relative contribution of various substituents on the steroid molecule for the binding affinity of the steroids. The introduction of a double bond at C1-C2, the presence of 9 alpha-fluoro atom or 11 beta-hydroxy group and the esterification of the 17 alpha-hydroxy group caused an increase, whereas esterification of the hydroxy group on C21 leads to marked decrease of the affinity of the steroid.

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.

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

The type of collagen synthesized by primary cultures of dermal fibroblasts from two different strains of mice (A/J and C57BL6/J) was investigated. Confluent cultures were grown for four days with or without 10(-6) and 10(-7) M corticosterone or 10(-6) M dexamethasone. Glucocorticoid treatment results in a lower type III/type I procollagen ratio in both strains. While the amount of type I procollagen remains unchanged, type III is reduced to about 25 per cent of control values in the cells from both mouse strains. Thus, glucocorticoids can modulate the types of collagen synthesized by cultured cells.

Effect of different doses of D-penicillamine and combined administration of D-penicillamine and methylprednisolone on collagen, glycosaminoglycans, DNA and RNA of granulation tissue, skin, bone and aorta in rats

D-penicillamine (D-pen) in doses of 20, 100 and 500 mg/kg/day or D-pen 100 mg/kg/day plus methylprednisolone (MP) 2.0 mg/kg/day was administered daily for 42 days to rats implanted with viscose-cellulose sponges. Operated, pairfed rats served as controls. D-pen increased the DNA content of granulation tissue, but had no effect on the amount of tissue produced. In contrast, high dose D-pen reduced the content of DNA and collagen in skin. A dose related inhibition of collagen crosslink formation occurred in all tissues, particularly in skin, as indicated by increased proportions of extractable collagen with increased alpha/beta chain ratio and aldehyde content. Moreover, low doses of D-pen increased the hydroxyproline/proline ratio of acid soluble skin collagen, presumably due to solubilization of type III collagen as demonstrated by SDS-polyacrylamide gel electrophoresis in the presence of 3.6 M urea. These changes were associated with increased skin fragility and edema plus excess elastin deposition in the aorta after high dose D-pen treatment. Low dose D-pen stimulated the 35S-sulphate uptake into the sulphated glycosaminoglycans (GAGs) of granulation tissue without altering their relative amounts, whereas high dose D-pen reduced the concentration of chondroitin-4/6-sulphate in skin. MP antagonized the solubilizing effect of D-pen on collagen, probably by inhibition of the collagen synthesis. In addition, MP inhibited the cell proliferation and GAG metabolism. Food restriction reduced the DNA content of granulation tissue. The inhibitory effect of D-pen on the formation of granuloma collagen crosslinks in the presence of unaltered rate of collagen biosynthesis may diminish the amount of fibrotic tissue due to increased degradability of crosslink deficient collagen. Simultaneous administration of MP may facilitate this effect by inhibiting the biosynthesis of collagen. However, long-term D-pen treatment seems to increase the susceptibility of normal tissues to mechanical injury.

Glucocorticoid receptors and inhibition of neonatal mouse dermal fibroblast growth in primary culture

Primary cultures of dermal fibroblasts from neonatal mice were used to investigate some of the anti-inflammatory effects of glucocorticoids in vitro as influenced by the genetic background of two different strains of mice (A/J and C47 Bl/6J). Fibroblasts were cultured in the absence or presence of various glucocorticoids for 2-7 days. After 4-7 days in the presence of steroid, DNA synthesis was reduced by 50-85% while protein synthesis was inhibited by 50-60%. Corticosterone produced a dose-dependent inhibition of DNA synthesis in these cells with a 50% reduction occurring at 10 nM. Specific, high affinity, low capacity binding proteins for [3H]dexamethasone or [3H]triamcinolone acetonide were identified in the cytoplasm of neonatal dermal fibroblasts which had an apparent Kd of 9 nM and approximately 5,200-6,400 binding sites/cell. Sedimentation analysis of the [3H]triamcinolone acetonide-receptor complexes on low salt glycerol gradients exhibited binding in the 7 to 8 S region of the gradients. These studies demonstrate that inhibition of growth of primary cultures of mouse neonatal dermal fibroblasts by glucocorticoids is probably mediated by a receptor-mediated pathway, and that this primary culture system might be useful in delineating other anti-inflammatory effects of glucocorticoids in vitro.

Corticoids and human skin fibroblasts: intracellular specific binding in relation to growth inhibition

The binding of 3H-triamcinolone acetonide to soluble macromolecules of cultured human skin fibroblasts was studied in an attempt to explain the mechanism underlying the inhibitory effects of glucocorticoids on cell growth. The results were as follows: Cultured human skin fibroblasts contain in cytosol a high affinity binding system for glucocorticoids. Various glucocorticoid derivatives competed for specific binding of 3H-triamcinolone acetonide. In some but not all instances this competition was related to the clinical efficacy of the derivatives under study and to their potency for the inhibition of cell growth. A specific glucocorticoid binding system was detectable in steroid-sensitive, low-density cell cultures (apparent Bmax = 200 fmoles/mg protein). The number of steroid binding sites was lower in high-density cell cultures (apparent Bmax = 125 fmoles/mg protein). The sensitivity to growth inhibition by glucocorticoids was markedly decreased in the high-density cell cultures. There were no differences in the affinity constants between these cell cultures (Kdiss. = 3.3 X 10-9 M). When cells were grown in medium containing glucocorticoid, renewal of the incubation medium led to disappearance of the growth-inhibitory effects, whereas specific binding was not affected. Nandrolone, an inhibitor of cell growth, abolished the growth-inhibitory effects of glucocorticoids but did not displace 3H-triamcinolone acetonide from its binding sites. The results suggest that in addition to a mechanism mediated by a glucocorticoid binding system with receptor like properties also other factors as well appear of relevance for the control of cell growth. These factors may be beyond the actual binding process of steroid and involve the action at the level of genomic expression of the cell.

Effects of corticosteroids on the proliferation of normal and abnormal human connective tissue cells

Four corticosteroids were tested in vitro for effect on the proliferation of four strains of fibroblasts from scleroderma skin, four strains from normal adult skin and four strains of rheumatoid synovial cells. Significant effects on fibroblasts occurred only at the highest steroid concentration tested (10 microgram/ml) where the inhibitory ranking of the steriods was clobetasol propionate greater than clobetasone butyrate greater than betamethasone valerate greater than hydrocortisone. Hydrocortisone and betamethasone valerate stimulated proliferation of two normal strains, had no certain effect on the scleroderma group, and inhibited growth of synovial cells. Clobetasone butyrate and clobetasol propionate inhibited growth of all cells. All four steroids substantially reduced acid mucopolysaccharide secretion by scleroderma fibroblasts. These results suggest that fibroblasts from normal and abnormal skin show only small differences in their responses to corticosteroids in vitro, but contrast sharply with the mouse L-929 fibroblasts previously used in some assays of topical corticosteroid potency.

Effects of glucocorticosteroids on cultured human skin fibroblasts. V. Influence of anabolic steroids on the inhibitory effects of clobetasol-17-propionate on cell proliferation and collagen synthesis

As previously found, the glucocorticosteroid clobetasol-17-propionate inhibits cell proliferation during the early growth stage of normal baby foreskin fibroblasts and collagen synthesis in confluent cultures of these cells. The degree of inhibition of cell proliferation decreases with increasing cell density and, moreover, is transient. The anabolic steroids nandrolone and nandrolone-phenyl-propionate have similar effects on these cells. Likewise the magnitude of the inhibition is dose-dependent. When present together the two types of drug do not act in an additive manner. Even at low concentrations the anabolic steroids abolish the inhibitory effect of the glucocorticosteroid on cell proliferation. Furthermore, in this case only the inhibitory effect of the glucocorticosteroid on collagen synthesis is found and there is no further increase in this effect due to the presence of the anabolic steroids. Our results imply that the use of low concentrations of anabolic steroids combined with glucocorticosteroids in topical application to the skin may abolish some of the undesirable side effects of the glucocorticosteroids.

Effects of glucocorticosteroids on cultured human skin fibroblasts. III. Transient inhibition of cell proliferation in the early growth stages and reduced susceptibility in later growth stages

An immediate depression of the rate of cell proliferation occurred upon addition of glucocorticosteroids to cultures of human skin fibroblasts in the early growth stages. A reduced sensitivity or even insensitivity of the fibroblasts to growth inhibition inhibition was found upon the addition of the steroids at later stages of cell growth, when the cell density has increased. The inhibition in the early growth stages is transient and is most pronounced if the cultured medium is not renewed. This transient inhibition is not due to the development of steroid-resistant cell lines, and resembles the effect called tachyphylaxis, as is also observed in vasoconstriction tests.

Comparative evaluation of skin atrophy in man induced by topical corticoids

In this in-patient study, mild skin atrophy was observed clinically in 6 out of a total of 22 patients after fluocinolone acetonide and in one patient after flumethasone pivalate ointment applications (P less than 0,05). Investigations were discontinued prematurely on days 14 and 17 in 2 patients because they developed early atrophy due to fluocinolone acetonide applications. Histological findings indicating either moderate or marked skin atrophy were evident in 15 patients after flucinolone acetonide as against one patient after flumethasone pivalate ointment applications (P less than 0.001). In comparison with the controls the mean decrease in epidermal thickness was more marked after fluocinolone acetonide applications, namely 30.5% vs 21.3% after flumethasone pivalate applications. The ultrastructural tissue changes were less marked at the sites to which flumethasone pivalate was applied. In comparison with controls, the percentages of mean decrease in diameters of collagen fibrils measured in six volunteer patients ranged from 5.1% to 27.6% after fluocinolone acetonide and from 0% to 12.3% following flumethasone pivalate ointment applications, This difference was statistically significant (range P less than 0,01 to less than 0.001). This experimental study has demonstrated that flumethasone pivalate displays only a mild atrophogenic effect and it is clinically and histologically significantly less atrophogenic than fluocinolone acetonide. Flumethasone pivalate can therefore be reckoned as a suitable topical corticosteroid especially for the long-term treatment of corticoid-responsive dermatoses.

Effects of glucocorticosteroids on primary human skin fibroblasts. I. Inhibition of the proliferation of cultured primary human skin and mouse L929 fibroblasts

Various glucocorticosteroids were added to logarithmically growing cultures of primary human skin fibroblasts and of mouse L929 fibroblasts. These steroids inhibited proliferation of the human fibroblasts at concentrations which fall in a range expected to occur during the topical treatment of skin disorders. In terms of the concentrations required for the inhibition hydrocortisone was least and clobetasol-17-propionate most effective. All other steroids studied (hydrocortisone-17-butyrate, triamcinolone acetonide, betamethasone-17-valerate and hydrocortisone-21-acetate) showed medium effectiveness. Fluorination as such may not enhance the inhibitory effect. The inhibition was independent of the source (baby foreskin or adult arm skin) and passage number (7th to 13th or 15th and 16th passage, respectively) of the cells. The possible relationship between the inhibition of cell proliferation by such steroids and their therapeutic effect in psoriasis and their atrophic side effects is discussed. Mouse L929 fibroblasts were affected at 10(3)--10(4)-fold lower steroid concentrations and the range of the effective concentrations was 10(4)--10(5) times as wide as that for the primary human skin fibroblasts. It was concluded that these mouse fibroblasts are a poor model system for the study of in vivo effects of glucocorticosteroids in man.