Keratinocyte-derived cytokines after photodynamic therapy and their paracrine induction of matrix metalloproteinases in fibroblasts

BACKGROUND: Recent studies have shown that collagen-degrading matrix metalloproteinase (MMP)-1 and MMP-3 are produced by fibroblasts in response to photodynamic therapy (PDT) with 5-aminolaevulinic acid (ALA) and are considered to be involved in the antisclerotic effects of ALA-PDT observed in the treatment of localized scleroderma. OBJECTIVES: As the primary target of topical PDT is epidermal keratinocytes, we studied the indirect participation of keratinocytes in the production of MMPs and collagen by dermal fibroblasts. METHODS: Keratinocytes were treated with sublethal doses of ALA (100 micromol L(-1)) and red light. The conditioned media were collected 24 h after PDT and primary human fibroblasts were exposed to these media for 6-48 h. Further, a coculture model, keratinocytes seeded on to collagen type IV-coated transwells in the upper chamber and fibroblasts in the lower chamber, was used to study paracrine effects of keratinocytes after PDT. RESULTS: Keratinocyte supernatants after PDT showed a significant, up to 10-fold increase of interleukin (IL)-1alpha and a 2.5-fold increase of tumour necrosis factor-alpha as determined by enzyme-linked immunosorbent assay, while IL-6, MMP-1 and MMP-3 were not altered significantly. Fibroblasts treated with keratinocyte-conditioned media after PDT showed an induction of MMP-1 and MMP-3 protein levels up to threefold in both models used, suggesting that ALA-PDT modulates MMP-1 and MMP-3 production via indirect mechanisms. Collagen type I mRNA expression by fibroblasts was not altered significantly in either model. The addition of an IL-1 receptor antagonist to the keratinocyte-conditioned media completely inhibited the induction of MMP-1 and MMP-3 in stimulated fibroblasts, suggesting that IL-1 is mainly responsible for the observed paracrine effects. CONCLUSIONS: We present evidence that PDT can trigger MMP production in dermal fibroblasts not only directly as has been already shown, but also by an indirect paracrine loop mediated by soluble factors released by epidermal keratinocytes.     

Activation of two caspase cascades,caspase 8/3/6 and caspase 9/3/6, during photodynamic therapy using a novel photosensitizer,ATX-S10(Na), in normal human keratinocytes

Background/purpose Photodynamic therapy (PDT) is a potent treatment for skin tumors. Although the therapeutic effect of PDT is supposed to be due to cellular cytotoxicity, the precise mechanism is still unknown. ATX-S10(Na) [13,17-bis(1-carboxypropionyl)carbamoylethyl-8-ethenyl-2-hydroxy-3-hydroxyiminoethylidene-2,7,12,18-tetramethylporphyrin sodium salt], a novel hydrophilic chlorin photosensitizer, shows good accumulation in tumors and is suitable for use in PDT. In this study, we investigated the mechanism of PDT-induced cell death using ATX-S10(Na).Methods Following ATX-S10(Na) treatment for 12 h, normal human keratinocytes (NHK) were irradiated using a diode laser. PDT-induced cell death and the activity of various caspases were measured. Activation of Fas antigen was also determined by immunoprecipitation analysis. The expression of Bax, cytochrome c, and apoptosis-inducing factor (AIF) was determined by Western blotting.Results ATX-S10(Na)-PDT had induced apoptosis of NHK by 2 h and the maximal effect was observed at 6 h following irradiation. The effect was suppressed by pretreatment of NHK with inhibitors of caspases 3, 6, 8 and 9. A caspase activity assay revealed the sequential activation of caspases 8, 3 and 6, and caspases 9, 3 and 6, respectively. Immunoprecipitation analysis indicated multimerization of Fas antigen without Fas ligand binding in ATX-S10(Na)-PDT-treated NHK. Western blotting revealed cytosolic release of cytochrome c and AIF accompanied by decreased Bax expression in the cytosol.Conclusions ATX-S10(Na)-PDT induces apoptosis of NHK, and this was mediated by sequential activation of two caspase cascades, caspases 8, 3 and 6, and caspases 9, 3 and 6. This was accompanied by multimerization of Fas antigen and cytosolic release of cytochrome c and AIF.     

基质金属蛋白酶表达在皮肤光老化皱纹形成中的作用

目的 探讨皮肤光老化皱纹形成与真皮成纤维细胞基质金属蛋白酶(MMP)-1,MMP-3mRNA及其组织抑制剂(TIMP)-1表达的关系。方法 采用原位杂交和免疫组化的方法检测紫外线光化学疗法(PUVA)治疗期间及治疗后不同时间银屑病患者背部非皮损区真皮成纤维细胞MMP-1,MMP-3mRNA及TIMP-1蛋白的表达并定量分析。结果 在PUVA治疗期间、治疗后1~6个月及治疗后6个月以上的银屑病患者背部非皮损区真皮成纤维细胞均持续表达MMP-1、MMP-3mRNA,而TIMP-1蛋白仅在治疗期间一过性轻度表达。结论 PUVA治疗引起的皮肤光老化皱纹形成可能与真皮成纤维细胞基质金属蛋白酶及其组织抑制剂表达失衡密切相关。     

Cutis laxa: analysis of metalloproteinases and extracellular matrix expression by immunohistochemistry and histochemistry

Upregulation of matrix metalloproteinases (MMPs) and downregulation of tissue inhibitors of metalloproteinases (TIMP) have been reported in cultured fibroblasts from patients with congenital cutis laxa (CL) or anetoderma. We determined the protein expressions of MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, TIMP-1 and collagen I, collagen III in vivo, to confirm their roles in the pathogenesis of cutis laxa. The protein expression of the MMPs and collagens from skin lesions of CL were detected by immunohistochemistry and analyzed by image analysis software. Markedly increased MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, TIMP-1 associated with alteration of elastic and collagen fibers were found in two cases of CL, whereas increased MMP-3, MMP-9, MMP-12 accompanying a degradation of elastic fibers were detected in the third case. These results suggest an elevated expression of MMPs may play a role in the evolution or genesis of CL.     

A novel ATX-S10(Na) photodynamic therapy for human skin tumors and benign hyperproliferative skin

BACKGROUND/PURPOSE: Photodynamic therapy (PDT) is a promising treatment for various skin tumors and other skin diseases. We investigated the potential therapeutic effects of PDT using ATX-S10(Na) ointment and a diode laser in mouse skin models of experimental skin tumors as well as transplanted human samples of superficial skin tumors and lesional psoriatic skin. METHODS: ATX-S10(Na) ointment (1% w/v) was introduced into tape-stripped mouse skin, transplanted squamous cell carcinoma (SCC) samples and human skin diseases after topical application, then PDT was performed. RESULTS: ATX-S10(Na) ointment (1% w/v) was introduced effectively into tape-stripped mouse skin and transplanted SCC samples after topical application, but was not detected after 48 h, as assessed by fluorescence microscopy. PDT, using 1% ATX-S10(Na) ointment and diode laser (50 J/cm(2)), was found to decrease epidermal thickness in 12-0-tetradecanoylphorbol-13-acetate (TPA)-treated mouse skin by 6 days. PDT with 1% ATX-S10(Na) ointment and diode laser (150 J/cm(2)) was also effective for transplanted SCC, and tumors were eliminated by 6 weeks. PDT against Bowen disease, basal-cell carcinoma, and psoriasis xenografts onto SCID mice also showed marked suppression of tumor growth and cell proliferation, respectively. CONCLUSION: Our results indicate that ATX-S10(Na)-PDT is an effective treatment for various skin tumors and psoriasis in experimental mouse models.     

Interleukin-1beta and macrophage migration inhibitory factor (MIF) in dermal fibroblasts mediate UVA-induced matrix metalloproteinase-1 expression

BACKGROUND: Exposure to solar UV radiation is the main environmental factor that causes premature aging of the skin. Matrix metalloproteinases (MMP)-1 is a member of the MMP family and degrades types I and III collagens, which are the major structural components of the dermis. OBJECTIVE: We evaluated the involvement IL-1beta and macrophage migration inhibitory factor (MIF) in MMP-1 expression under ultraviolet A (UVA) irradiation. METHODS: IL-1beta and MIF in MMP-1 expression in cultured human dermal fibroblasts and the UVA effects on MMPs production using IL-1alpha/beta-deficient mice were analyzed. Furthermore, fibroblasts derived from MIF-deficient mice were used to analyze the effect of IL-1beta-induced MMPs production. RESULTS: IL-1beta-enhanced MIF expression and induced MMP-1 in cultured human dermal fibroblasts. IL-1beta-induced MMP-1 expression is inhibited by neutralizing anti-MIF antibody. Dermal fibroblasts of IL-1alpha/beta-deficient mice produced significantly decreased levels of MMPs compared to wild-type mice after UVA irradiation. Furthermore, fibroblasts of MIF-deficient mice were much less sensitive to IL-1beta-induced MMPs production. On the contrary, IL-1beta produced significantly decreased levels of MMPs in MIF-deficient mice fibroblasts. The up-regulation of MMP-1 mRNA by IL-1beta stimulation was found to be inhibited by a p38 inhibitor and a JNK inhibitor. In contrast, the MEK inhibitor and inhibitor were found to have little effect on expression of MMP-1 mRNA. CONCLUSIONS: IL-1beta is involved in the up-regulation of UVA-induced MMP-1 in dermal fibroblasts, and IL-1beta and MIF cytokine network induce MMP-1 and contribute to the loss of interstitial collagen in skin photoaging.     

Alteration of extracellular matrix modulators after nonablative laser therapy in skin rejuvenation

BACKGROUND: Nonablative laser therapy is widely practised for skin rejuvenation, which stimulates collagen production and dermal matrix remodelling. Matrix remodelling is primarily modulated by a coordinated action of matrix metalloproteinases (MMPs) and their inhibitors, but the effects of nonablative lasers on these matrix modulators are not fully investigated. OBJECTIVES: To evaluate the changes in matrix modulators, such as MMP-1, MMP-2, MMP-3, MMP-9 and MT1-MMP, and their inhibitors (TIMP-1, TIMP-2 and RECK in particular), after nonablative laser treatments of human facial skin. METHODS: Twenty-four adult volunteers received a series of four nonablative laser treatments separated by 3-week intervals on facial skin. Two-millimetre skin punch biopsies were obtained at baseline and 3 weeks after the last treatment. RESULTS: Nonablative laser treatments led to a robust increase in two major dermal matrix components, type I collagen and tropoelastin. Among MMPs tested, levels of MMP-2 mRNA were statistically significantly increased, but the amount of active MMP-2 was rather reduced. More importantly, the expression level of RECK was significantly enhanced by laser treatments. CONCLUSIONS: Clinical outcomes following nonablative laser treatments may result not only from increased biosynthesis but also from decreased degradation, via an induction of RECK expression, of matrix proteins.     

Photodynamic therapy using a novel photosensitizer,ATX-S10(Na): comparative effect with 5-aminolevulinic acid on squamous cell carcinoma cell line,SCC15, ultraviolet B-induced skin tumor,and phorbol ester-induced hyperproliferative skin

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) is available for the treatment of actinic keratosis (AK). Recently, we developed a new PDT photosensitizer, ATX-S10(Na), and have shown that ATX-S10(Na) PDT is effective for the treatment of various human skin diseases, such as squamous cell carcinoma, Bowens disease, basal cell carcinoma, and psoriasis. In the present study, we compared the effects of ATX-S10(Na) PDT and ALA PDT on hyperproliferative skin induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), on the squamous cell carcinoma cell line, SCC15, in vitro, and on UVB-induced skin tumors in vivo. TPA treatment induced epidermal acanthosis, which was more markedly suppressed by ATX-S10(Na) PDT than by ALA PDT. ATX-S10(Na) PDT more effectively eliminated UVB-induced AK and squamous cell carcinoma (SCC) than ALA PDT. Furthermore, both ATX-S10(Na) PDT and ALA PDT induced the death of SCC15 cells, and the effect of ATX-S10(Na) PDT was greater than that of ALA PDT. Our results indicate that ATX-S10(Na) PDT might be more effective than ALA PDT for the treatment of various skin diseases.     

Influence of cultured dermal fibroblasts on human melanoma cell proliferation,matrix metalloproteinase-2 (MMP-2) expression and invasion in vitro

The dermis is the main site of melanoma invasion. Matrix metalloproteinases (MMPs), especially MMP-2, produced by melanoma or surrounding stromal cells, are essential for the destruction of dermal extracellular matrix. Here, we examined how dermal fibroblasts influenced proliferation, MMP-2 secretion and invasion of human melanoma cell lines in vitro. Human melanoma cell lines M3 Da and M1Dor were cocultured with dermal fibroblasts under non-contact and contact conditions in order to assess both soluble and insoluble factors, respectively. Zymographic analysis showed that the levels of MMP-2 and TIMP-2 in melanoma cells were not altered in non-contact cocultures when compared with those in individual cultures. However, in contact cocultures, the expression of MMP-2 in membrane extracts was enhanced. Under our coculture conditions, dermal fibroblasts failed to upregulate melanoma cell invasion through a three-dimensional type I collagen matrix. Since stromal and cancer cell contacts have been shown to occur after disruption of the extracellular matrix, we hypothesized that fibroblasts may influence melanoma cell invasion after the beginning of tumor progression through the dermis.     

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.     

Human Scalp Dermal Papilla and Fibrous Sheath Cells have a different expression profile of Matrix Metalloproteinases <Emphasis Type="Italic">in vitro</Emphasis> when compared to Scalp Dermal Fibroblasts

The dermal papilla is a cluster of specialised mesenchymal cells at the bottom of the mammalian hair follicle, embedded in a loose extracellular matrix. These cells have the capability to induce and support hair growth via close epithelial–mesenchymal interactions with the keratinocytes surrounding the hair matrix. The extracellular matrix of the dermal papilla differs markedly from the interfollicular matrix and plays a key role in the maintenance of hair growth. In this study we investigated the expression pattern and activity of matrix metalloproteinases (MMP) and their tissue inhibitor in in vitro cultures of cells derived from scalp dermal papilla and fibrous sheath. Expression and activity of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2 and MT1-MMP were analysed in those cells cultured in contact with one of the relevant protein component of the dermal matrix, collagen type I as well as in monolayer. Zymographic analysis showed activation of MMP-2 in all cells grown in three-dimensional collagen lattices whereas MMP-9 was activated only in three-dimensional collagen cultures of dermal fibroblasts and weakly in follicular cells. Expression of MMP-1, TIMP-1, TIMP-2 and MT1-MMP was similar in all cells, in both culture conditions, whereas expression of MMP-3 was absent in dermal papilla cells. In addition to a series of reported morphological and functional differences between dermal fibroblasts and the dermal mesenchyme-derived cells of the hair follicle, we reported differences in MMP expression in dermal papilla and fibrous sheath cells within the mesenchymal population of the hair follicle.     

Gene expression of types I and III collagen, decorin, matrix metalloproteinases and tissue inhibitors of metalloproteinases in skin fibroblasts from patients with systemic sclerosis

Cultured fibroblasts from patients with systemic sclerosis (SSc) and normal individuals were examined for gene expression of types I and III collagen, decorin, matrix metalloproteinases (MMP) MMP-1, MMP-2, and MMP-3, tissue inhibitors of metalloproteinases (TIMP) TIMP-1 and TIMP-2, urokinase- and tissue-type plasminogen activators (u-PA and t-PA). Fibroblasts from patients with early stage SSC (less than 1 year duration of disease) exhibited higher levels of types I and III procollagen, decorin, MMP-1, MMP-3, TIMP-1, and PAs than those from normal individuals. The gene expression of procollagen α1(I) and TIMP-1 mRNAs were increased, but those of decorin, MMP-1, MMP-2, and MMP-3 were decreased, in fibroblasts from SSc patients with mid-stage SSc (2 to 4 years duration) as compared with those from normal individuals. In contrast, no significant difference in gene expression was found between fibroblasts from normal individuals and from patients with late-stage SSc (more than 6 years duration). These results suggest that gene expression of collagen, decorin, and degrading factors is dynamically modulated during fibrillogenesis. The responses of procollagen α1(I) mRNA to IL-1 and TGF-β were lower in fibroblasts from SSc patients with early and mid-stage disease, but not in those from patients with-late stage disease, than in control fibroblasts, which indicates that these cytokines may be involved in the earlier phases of fibrosis in SSc. Received: 30 August 1996     

Keloid-derived fibroblasts show increased secretion of factors involved in collagen turnover and depend on matrix metalloproteinase for migration

BACKGROUND: A keloid is a specific skin lesion that expands beyond the boundaries of the original injury as it heals. Histologically, it is characterized by the excessive accumulation of collagen. However, the reasons for the expansion and the invasive nature of keloids remain unknown. OBJECTIVES: We evaluated collagen degradation and migration by cultured keloid fibroblasts based on the assumption that these variables were of functional relevance to the expanding and invasive nature of keloid lesions. METHODS: Collagen production was investigated by the detection of type 1 collagen (procollagen type 1C peptide: P1P). Matrix metalloproteinase (MMP)-1 (interstitial collagenase) and MMP-2 (gelatinase-A), were investigated as elements of the collagen degradation system. Enzyme immunoassays were performed to measure the production of P1P, MMP-1, MMP-2, and tissue inhibitor of metalloproteinase (TIMP)-1. To assess the production of MMP-2 its gelatinolytic activity was measured by zymography using gelatin-containing gels. The participation of transforming growth factor-beta1 (TGF-beta1) in the production and degradation of collagen was also investigated. Finally, the migratory activity of keloid fibroblasts was evaluated using a colony dispersion assay. RESULTS: The production of type 1 collagen, MMP-1, MMP-2, and TIMP-1 by keloid fibroblasts was 3-fold, 6-fold, 2.4-fold, and 2-fold greater than that of normal dermal fibroblasts, respectively. Production of P1P was increased when TGF-beta1 was added to cultures of keloid fibroblasts, while it was decreased when anti-TGF-beta1 antibody was added to the cultures. In contrast, the production of MMP-1 was decreased by the addition of TGF-beta1 to cultured keloid fibroblasts, while it was increased when anti-TGF-beta1 antibody was added to the cultures. The production of MMP-2 increased after treatment with TGF-beta1, but did not change significantly when anti-TGF-beta1 antibody was added to the cultures. Production of TIMP-1 did not change significantly when either TGF-beta1 or anti-TGF-beta1 antibody was added to the cultures. Keloid fibroblasts showed a 2.5-fold increase of migratory activity compared with normal dermal fibroblasts, while the migratory activity of these fibroblasts was reduced to the control level by treatment with a broad-spectrum MMP inhibitor (GM 6001). CONCLUSIONS: Cultured keloid fibroblasts showed increased production of collagen and MMPs, and TGF-beta1 played a role in this regulation of production. In addition, increased production of MMPs had a role in the high migratory activity of cultured keloid fibroblasts.     

Catalase restores the altered mRNA expression of collagen and matrix metalloproteinases by dermal fibroblasts exposed to reactive oxygen species

We investigated the effects of reactive oxygen species (ROS) on mRNA expression of proalpha1(I) collagen, proalpha1(III) collagen, matrix metalloproteinases-1 (MMP-1), 72 kDa type IV collagenase (MMP-2), and tissue inhibitor of metalloproteinase (TIMP-1) by normal human dermal fibroblasts in a novel three-dimensional culture. Fibroblasts exposed to ROS generated by the hypoxanthine-xanthine oxidase system revealed an increased mRNA expression of MMP-1 and MMP-2 with a maximum at 48 h and 72 h after exposure. A slight increase in the mRNA level of tissue inhibitor of metalloproteinase (TIMP-1) was observed. Increased protein level of MMP-1 and its collagenolytic activity and gelatinolytic activity of MMP-2 was comfirmed as well. In contrast, a time-dependent suppression of both proalpha1(I) and proalpha1(III) collagen mRNA expression was observed 12 h after ROS treatment with a maximum at 48 h and 72 h. Addition of catalase totally abrogated the ROS-induced alteration of these genes. Superoxide dismutase (SOD) abrogated only the increased mRNA expression of MMP-2. These results indicated that ROS mediates the induction of collagenases as well as the suppression of collagen synthesis by dermal fibroblasts in vitro. The biological alterations in collagen metabolism triggered by ROS may be responsible for the development of certain diseases or pathological changes such as photoaged human skin.     

The effects of epigallocatechin-3-gallate on extracellular matrix metabolism

BACKGROUND: Anti-oxidants have attracted a lot of interest on account of their function to protect the skin from oxidative stress by ultraviolet (UV) radiation. OBJECTIVE: This study examined the effects of epigallocatechin-3-gallate (EGCG), which is a green tea extract, on the extracellular matrix (ECM) changes induced by UV radiation and showed the comparative results with retinoic acid (RA). METHODS: The ECM metabolism is tightly controlled by the collagen degrading matrix metalloprotienases (MMPs) and their tissue inhibitors (TIMPs). Therefore, the expression of MMPs and TIMP-1 was investigated to evaluate the effects of EGCG and RA. Artificial skin was made using three-dimensionally cultured keratinocytes on a collagen matrix populated with fibroblasts. EGCG and RA were added into the medium of the fibroblasts and keratinocytes culture and also applied topically on artificial skins prior to UVA irradiation. The MMPs and TIMP-1 expression levels were measured using Western blot and a zymogram. RESULTS: EGCG, like RA, decreased the level of MMPs production and increased TIMP-1 expression level. However, EGCG suppressed the activities of the gelatinases and augmented the expressions of the TIMP-1 more than RA did. RA decreased the MMP-1 and MMP-3 expression levels to a greater extent than EGCG. ECM alterations as a result of UVA appeared to be prevented more effectively using the EGCG treatment. CONCLUSION: EGCG can reverse the ECM degradation induced by UV even with a topical application of a practical-use concentration. In particular, EGCG proved to be much more effective in ROS-related conditions, such as UVA exposure.     

Comparative caustic and biological activity of trichloroacetic and glycolic acids on keratinocytes and fibroblasts in vitro

OBJECTIVES: Beside their causticity, the biological mechanism by which trichloroacetic acid (TCA) and glycolic acid (GA), two agents extensively used for chemical peeling, might act remains unknown. The purpose of this study was to examine in vitro the effect of TCA and GA on human keratinocytes and the influence of the released epithelial mediators on collagen and matrix metalloproteinases (MMPs) production by human dermal fibroblasts. METHOD: Cultured keratinocytes were treated by TCA and GA at 10 mg/ml brought to pH 3, 5 and 7, and the conditioned media neutralized to pH 7 were added to human normal skin fibroblasts. RESULTS: TCA was cytotoxic for keratinocytes at each tested pH. The conditioned medium depressed protein and collagen synthesis and the expression of MMPs when added to fibroblasts as did also TCA when added directly to fibroblasts. GA was not cytotoxic for keratinocytes at neutral pH and the conditioned medium obtained at each pH applied to fibroblasts did not alter protein, collagen nor MMPs production while causing an elevated secretion of IL-6. CONCLUSION: TCA exerts a toxic effect on keratinocytes and fibroblasts while GA does not alter the metabolism of fibroblasts but induces the secretion of IL-6.     

Modulation of collagen metabolism by the topical application of dehydroepiandrosterone to human skin

Dehydroepiandrosterone (DHEA) and its sulfate conjugate (DHEA-S) are the most abundantly produced human adrenal steroids to be reduced with age. DHEA may be related to the process of skin aging through the regulation and degradation of extracelluar matrix protein. In this study, we demonstrate that DHEA can increase procollagen synthesis and inhibit collagen degradation by decreasing matrix metalloproteinases (MMP)-1 synthesis and increasing tisuue inhibitor of matrix metalloprotease (TIMP-1) production in cultured dermal fibroblasts. DHEA was found to inhibit ultraviolet (UV)-induced MMP-1 production and the UV-induced decrease of procollagen synthesis, probably due to the inhibition of UV-induced AP-1 activity. DHEA (5%) in ethanol:olive oil (1:2) was topically applied to buttock skin of volunteers 12 times over 4 weeks, and was found to significantly increase the expression of procollagen alpha1(I) mRNA and protein in both aged and young skin. On the other hand, topical DHEA significantly decreased the basal expression of MMP-1 mRNA and protein, but increased the expression of TIMP-1 protein in aged skin. We also found that DHEA induced the expressions of transforming growth factor-beta1 and connective tissue growth factor mRNA in cultured fibroblasts and aged skin, which may play a role in the DHEA-induced changes of procollagen and MMP-1 expression. Our results suggest the possibility of using DHEA as an anti-skin aging agent.