Bleomycin increases steady-state levels of type I collagen, fibronectin and decorin mRNAs in human skin fibroblasts

Abstract Bleomycin is a drug capable of inducing tissue fibrosis. In this study, the effects of bleomycin on gene expression of extracellular matrix encoding ·1(I) collagen, fibronectin and decorin were determined in vitro in human dermal fibroblasts. Northern blot analysis showed that bleomycin upregulated ·1(I) collagen, fibronectin and decorin gene expression dose-dependently between 1 nM and 1 μM. Bleomycin at 100 nM upregulated α1(I) collagen, fibronectin and decorin mRNA expression with a peak at 6 h following stimulation in normal skin fibroblast monolayers. Bleomycin enhanced mRNA expression encoding these extracellular matrix proteins in both normal dermal and scleroderma fibroblasts. Concomitant stimulation with bleomycin and interferon-γ (1000 U/ml), a representative antifibrotic cytokine, decreased ·1(I) collagen mRNA expression. Bleomycin also mildly upregulated mRNA expression of transforming growth factor-‚ (TGF-‚) and connective tissue growth factor (CTGF) coordinately in normal skin fibroblasts. Our results indicate that bleomycin modulates gene expression of extracellular matrix proteins in dermal fibroblasts, and this effect may be mediated by TGF-‚ and CTGF. Received: 20 April 2000 / Revised: 19 June 2000 / Accepted: 4 September 2000     

The role of ceramides in skin homeostasis and inflammatory skin diseases

Ceramides, members of sphingolipid family, are not only the building blocks of epidermal barrier structure, but also bioactive metabolites involved in epidermal self-renewal and immune regulation. Hence, abnormal ceramide expression profile is recognized to defect extracellular lipid organization, disturb epidermal self-renewal, exacerbate skin immune response and actively participate in progression of several inflammatory dermatoses, exemplifying by psoriasis and atopic dermatitis. Here, we discuss recent advances in understanding skin ceramides and their regulatory roles in skin homeostasis and pathogenic roles of altered ceramide metabolism in inflammatory skin diseases. These insights provide new opportunities for therapeutic intervention in inflammatory dermatoses.     

Intracellular collagen fibrils in cultured human skin.

During cultivation, the collagen fibrils of skin explants are broken down. The cells of the explants participate in this resorption. The ultrastructure of the intracellular degradation of collagen fibrils of cultured human skin has been examined. Intracellular collagen fibrils occur in fibroblasts, macrophages, smooth muscle cells and unidentifiable cells. Normal collagen fibrils are engulfed and appear within membrane-bounded tubes of the cytoplasm. Primary lysosomes fuse with the tubes. Degraded intracellular collagen fibrils are frequently present in secondary lysosomes and show decreasing diameters, filamentous splitting, loss of axial periodicity, variable stainability and cross-banded filamentous aggregates. The changes in the intracellular collagen fibrils are identical with those seen in the extracellular space. The present study demonstrates that various cell types in dermis are involved in collagen fibril degradation and that the lysosomes play an important part in the intracellular resorption.     

Modulation of skin collagen metabolism by irradiation: collagen synthesis is increased in irradiated human skin

Radiation-induced fibrosis is a common side-effect of cancer treatment. The pathophysiological events leading to fibrosis are not known in detail. We analysed the effect of therapeutic irradiation on human skin collagen synthesis, skin thickness, gelatinases and their inhibitors. Twenty randomly chosen women who had been treated for breast cancer with surgery and radiation therapy participated in the study. In each patient, the irradiated skin area was compared with a corresponding non-treated skin area. Suction blister fluid (SBF) and serum samples were analysed for the aminoterminal propeptides of type I and type III procollagens (PINP and PIIINP), tissue inhibitors of matrix metalloproteinases (MMPs) 1 and 2 (TIMP-1 and TIMP-2) and MMP-9 and MMP-2/TIMP-2 complex. Skin biopsies were analysed for PINP and immunohistochemical staining was used for PIIINP. In irradiated skin, PINP, PIIINP, TIMP-1 and MMP-2/TIMP-2 complex levels in SBF and the number of PINP-positive fibroblasts in tissue sections were significantly higher in comparison with non-treated skin. The levels of TIMP-2 in irradiated and non-irradiated skin were similar. MMP-9 could not be detected in SBF with the assay used. The serum levels of MMP-9 were higher in the treated subjects than the reference values. The serum values of PINP, PIIINP, TIMP-1, TIMP-2 and MMP-2/TIMP-2 complex were not significantly affected. These results indicate increased local collagen synthesis and accumulation of connective tissue in irradiated skin. The marked upregulation of collagen synthesis as a result of irradiation offers a possibility to treat this complication with compounds such as topical steroids which downregulate collagen synthesis.     

Bifidobacterium-fermented soy milk extract stimulates hyaluronic acid production in human skin cells and hairless mouse skin

We examined the effects of Bifidobasterium-fermented (BE) and nonfermented (SME) soy milk extracts on the production of hyaluronic acid (HA) in vitro and in vivo. BE, but not SME, significantly enhanced the production of HA in monolayer and organotypic cultures of human keratinocytes, in cultures of human skin fibroblasts, and in hairless mouse skin following topical application for 2 weeks. In the organotypic cultures formed by a similar structure to human epidermis, BE also extended the distribution of HA. Genistein and daidzein, known to stimulate HA production, were detected in BE at a concentration of 0.18 and 0.07 mM, respectively, but not in SME. Therefore, BE has the potential to enhance HA production in the epidermis and dermis, mainly due to genistein released from its glycoside during fermentation. BE is expected to prevent the age-dependent loss of cutaneous HA.     

Modulation of skin collagen metabolism in aged and photoaged human skin in vivo.

To the best of our knowledge, no study has been conducted to date to directly compare the collagen metabolism of photoaged and naturally aged human skin. In this study, we compared collagen synthesis, matrix metalloproteinase-1 levels, and gelatinase activity of sun-exposed and sun-protected skin of both young and old subjects. Using northern blot analysis, immunohistochemical stain, and Western blot analysis, we demonstrated that the levels of procollagen type I mRNA and protein in photoaged and naturally aged human skin in vivo are significantly lower than those of young skin. Furthermore, we demonstrated, by northern blot analysis, that the procollagen alpha1(I) mRNA expression of photoaged skin is much greater than that of sun-protected skin in the same individual. In situ hybridization and immunohistochemical stain were used to show that the expression of type I procollagen mRNA and protein in the fibroblasts of photoaged skin is greater than for naturally aged skin. In addition, it was found, by Western blot analysis using protein extracted from the dermal tissues, that the level of procollagen type I protein in photoaged skin is lower than that of naturally aged skin. The level of matrix metalloproteinase-1 protein and the activity of matrix metalloproteinase-2 were higher in the dermis of photoaged skin than in naturally aged skin. Our results suggest that the natural aging process decreases collagen synthesis and increases the expression of matrix metalloproteinases, whereas photoaging results in an increase of collagen synthesis and greater matrix metalloproteinase expression in human skin in vivo. Thus, the balance between collagen synthesis and degradation leading to collagen deficiency is different in photoaged and naturally aged skin.     

Effect of histamine on collagen and collagen m-RNA production in human skin fibroblasts.

Direct effects of histamine on collagenous and non-collagenous protein synthesis by human skin fibroblasts were studied. Fibroblasts derived from human skin were incubated with various concentrations of histamine. Collagen and non-collagenous protein synthesis were measured by incorporation of 3H-proline. Both collagen synthesis measured as protein-bound hydroxyproline and non-collagenous protein synthesis measured as protein-bound proline increased in the presence of histamine at concentrations of 10(1)-10(2) micrograms/ml. Total RNA was extracted and m-RNA levels of various proteins were estimated by dot blot analysis, and densitometrically quantified. The levels of alpha 1(I) collagen and beta-actin m-RNA were clearly increased at the same concentrations. m-RNA levels of alpha 1(III) collagen were also increased but the rate was lower than that of alpha 1(I) collagen. No alteration of beta-tubulin m-RNA level was observed at the same concentrations. These results demonstrate that stimulation of collagen synthesis by histamine is pretranslationally controlled.     

Decreased collagen and hyaluronic acid content in lesional skin of acrogeria

Biochemical analysis of involved and uninvolved skin of a 16-year-old female with acrogeria showed that hyaluronic acid and collagen contents were decreased only in involved skin. Explant cultures from both involved and uninvolved skin synthesized mainly hyaluronic acid in similar amounts. Since the glycosaminoglycans and hydroxyproline excreted in the urine were not increased, we speculate that a localized rather than a systemic abnormality may be present in acrogeria. Decreased collagen and hyaluronic acid contents in the patient are discussed in relation to Werner's syndrome and type IV Ehlers-Danlos syndrome.     

Betulinic acid induces apoptosis in skin cancer cells and differentiation in normal human keratinocytes

Betulinic acid (BA), a pentacyclic triterpene of plant origin, induces cell death in melanoma cells and other malignant cells of neuroectodermal origin. Little is known about additional biological effects in normal target cells. We show, in this study, that BA induces differentiation as well as cell death in normal human keratinocytes (NHK). Cytotoxicity profiles of BA are compared among normal human keratinocytes, HaCaT cells, IGR1 melanoma cells and normal melanocytes. As expected, BA is toxic to all cell types, normal and malignant, but varies in its cytotoxic potency and in the extent of induction of apoptotic vs. necrotic cell death in the four different skin cell types. Apoptosis is proved by annexin V and Apo2.7 binding and by DNA fragmentation. Induction of differentiation-associated antigens in keratinocytes--filaggrin and involucrin--is demonstrated, together with specific morphological changes in treated cell cultures. BA, apart from its cytotoxic activities in cellular systems, is capable of inducing differentiation of NHK into corneocytes without immediately provoking apoptotic cell death.     

Smoking affects collagen synthesis and extracellular matrix turnover in human skin

BACKGROUND: Smoking is associated with premature facial wrinkling and aberrant wound healing, but the underlying mechanisms of skin injury are poorly understood. OBJECTIVES: To compare the in vivo collagen synthesis and degradation in the skin of smokers and non-smokers. METHODS: The study population consisted of 47 current smokers and 51 individuals who had never smoked from northern Finland. Suction blisters were induced in the sun-protected upper inner arm of the study subjects, after which suction blister fluid (SBF) was collected for analyses of the levels of aminoterminal procollagen propeptides of type I and III collagens (PINP and PIIINP, respectively), matrix metalloproteinase (MMP)-8 and tissue inhibitor of MMP (TIMP)-1. PINP, PIIINP and TIMP-1 were also determined from serum samples. The levels of active and pro MMP-1 were assessed from deep-frozen skin biopsies by Western blotting. RESULTS: The synthesis rates of type I and III collagens were lower by 18% and 22%, respectively, in the SBF of the smokers compared with the non-smokers. The levels of MMP-8 were higher by 100% in the SBF of the smokers. The levels of MMP-1 in the skin biopsies did not differ significantly between the groups. The levels of TIMP-1 in SBF were 14% lower in the smokers than in the non-smokers, whereas the serum concentrations of TIMP-1 did not differ between the groups. CONCLUSIONS: Smoking decreases the synthesis rates of type I and III collagens in skin in vivo and alters the balance of extracellular matrix turnover in skin.     

Immunohistochemical localization of type V collagen in normal human skin

Summary Tissue distribution of type V collagen in normal human skin was studied using an indirect immunofluorescent technique to determine whether type V collagen is present in the interstitium or in the basement membrane. Type V collagen was isolated from the human placenta by pepsin digestion and was purified with fractioning salt precipitations. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that type V collagen contained 1(V) and 2(V) chains, but not the 3(V) chain. Specificity of the rabbit antibodies to type V collagen was assessed using enzyme-linked immunosorbent assay (ELISA) and an immunoblotting method. Antibodies showed no cross-reactivity to other collagens, laminin, and fibronectin. With an indirect immunofluorescent technique, type V collagen was found to be widely distributed throughout the dermis. Intense fluorescent staining was noted in the papillary dermis and adnexal dermis surrounding hair follicles and eccrine glands. The basement membrane of the dermoepidermal junction, skin appendages, and capillaries was not stained. By indirect immunoperoxidase double staining, type V collagen was not found to be deposited on type IV collagen present in the basement membrane. Immunoelectron microscopic studies showed that type V collagen was not located in the basal lamina. These results suggest that type V collagen is distributed in the interstitium, but not in the basement membrane of normal human skin.     

Regulated proenkephalin expression in human skin and cultured skin cells

Skin responds to environmental stressors via coordinated actions of the local neuroimmunoendocrine system. Although some of these responses involve opioid receptors, little is known about cutaneous proenkephalin expression, its environmental regulation, and alterations in pathology. The objective of this study was to assess regulated expression of proenkephalin in normal and pathological skin and in isolated melanocytes, keratinocytes, fibroblasts, and melanoma cells. The proenkephalin gene and protein were expressed in skin and cultured cells, with significant expression in fibroblasts and keratinocytes. Mass spectroscopy confirmed Leu- and Met-enkephalin in skin. UVR, Toll-like receptor (TLR)4, and TLR2 agonists stimulated proenkephalin gene expression in melanocytes and keratinocytes in a time- and dose-dependent manner. In situ Met/Leu-enkephalin peptides were expressed in differentiating keratinocytes of the epidermis in the outer root sheath of the hair follicle, in myoepithelial cells of the eccrine gland, and in the basement membrane/basal lamina separating epithelial and mesenchymal components. Met/Leu-enkephalin expression was altered in pathological skin, increasing in psoriasis and decreasing in melanocytic tumors. Not only does human skin express proenkephalin, but this expression is upregulated by stressful stimuli and can be altered by pathological conditions.     

Immunohistochemical studies comparing the localization of type XV collagen in normal human skin and skin tumors with that of type IV collagen

We investigated the localization of type XV collagen in normal human skin and skin tumors by immunohistochemical methods using a monoclonal antibody against the recombinant polypeptide of the non-collagenous region of the alpha1 chain of murine type XV collagen. Type XV collagen was localized in the dermo-epidermal, perivascular, and perineural basement membrane zones in normal skin. While this localization appeared to be similar to that of type IV collagen, detailed observation revealed that its localization was distinct in fact from that of type IV collagen which was thin and linear in appearance and was distributed inside organs. Type XV collagen was distributed broadly and zonally outside organs such as vascular and neural tissues. It was expressed at low levels in seborrheic keratosis and not expressed at all in actinic keratosis and squamous cell carcinoma. Melanocytic nevi and malignant melanomas in situ were positive for type XV collagen; melanomas with dermal invasion were negative. These findings suggest that type XV collagen plays a role in the adherence of the basement membrane to surrounding connective tissue and that it may be associated with the tumorigenesis of keratinocytes and melanocytes.     

Parallel studies on collagen hydroxyproline and hydroxylysine in human skin biopsies.

Studies on hydroxyproline and hydroxylysine, the two amino acids characteristic of collagen and related glycoproteins, were undertaken on biopsies of pathologic and clinically normal human skin. No statistically significant differences between clinically normal skin of mamma, thorax, axilla, femur, hip and sacral area were found. A decreased collagen content was seen in chronic pemphigus (bullous pemphigoid), amyloidosis, scleromyxedema and the edge of a leg ulcer. Determination of both amino acids is considered necessary to characterize alterations of collagen.