Skin pharmacology : the official journal of the Skin Pharmacology Society最新文献

Activity and inhibition of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase, a key example of biosynthesis of androgenic steroids, in human skin were studied. Whole-width dermal tissue specimens excised from various regions of the male and female body were investigated with an in vitro radioenzyme assay method using dehydroepiandrosterone as substrate. The Michaelis-Menten constant of the enzyme was found to be Km = 10nM and the maximal velocity was Vmax = 0.625 pmol produced 4-androstene-3,17-dione/mg protein/20 min. Activity of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase in male inguinal skin (n = 8) was 0.132-0.412, in female abdominal skin (n = 4) 0.140-0.255, in perineal skin (n = 4) 0.138-0.962 pmol/mg protein/20 min. The synthetic steroids cyproterone acetate, 4-MA and epostane proved to be potent inhibitors, IC50 values were 150, 6.2 and 1.45 nM, respectively.

As yet, topically applied isotretinoin fails to show convincing clinical efficacy in the treatment of severe recalcitrant acne. Although the reason for this is not known, it is possible that topical application results in low, pharmacologically inactive isotretinoin concentrations in the sebaceous glands, the most likely site of isotretinoin action. It has been suggested that topically applied liposomes enhance the delivery of drugs into the sebaceous glands. Accordingly, we compared the isotretinoin concentration in sebaceous glands and other skin compartments following topical application of small unilamellar vesicles, multilamellar vesicles, preformed vesicles (Natipide II) or mixed micelles of lecithin and bile salt. We found that the concentration of isotretinoin measured in the sebaceous glands varied between 0.17 and 1.57 ng/mg tissue. The comparison between ethanolic gel and liposomal or micellar gel did not reveal any significant difference. However, application of the Natipide formulation resulted in significantly lower isotretinoin concentrations in the sebaceous glands when compared to the ethanolic gel. Autoradiography and fluorescence microscopy indicated that isotretinoin penetrated the sebaceous glands along the follicular route. In conclusion, our in vitro study showed that, following topical administration, substantial amounts of isotretinoin were delivered to the sebaceous glands via the follicular route, whereby the ethanolic gel was as efficient as a liposomal or a mixed micellar gel.

To evaluate the epidermal barrier function of in vitro reconstructed epidermis, we measured the penetration of estradiol and water across human keratinocytes cultured in defined medium (DM), in the presence of proliferative fibroblasts (pF) or conditioned medium derived from pF, at the air-liquid interface on synthetic porous membrane, noncoated or coated with laminin, fibronectin, type I collagen or type IV collagen. Ultrastructural analysis showed a well-developed stratum corneum whatever the culture conditions. The permeability of reconstructed epidermis in DM on a noncoated porous membrane was 5- to 10-fold higher than human native epidermis, with both tracers. No significant change in barrier function was observed whatever the culture conditions.

Objective: In order to assess the proliferative changes induced by all-trans retinoic acid (RA) and retinol (ROL), we have carried out a study of the DNA content of basal and suprabasal keratinocytes after epicutaneous application on the rhino mouse.

Study design: Skin sections were analyzed stereologically and cytophotometrically using the Feulgen technique. The diploid DNA value (2C) was obtained from hepatocyte nuclei of control animals. Whereas cells in phase G0-G1 will show a 2C content, cells during phase S and in phase G2-M will show DNA values ranging from 2C to 4C and 4C, respectively.

Results: Although epidermal thickness (ET) increased significantly in all treated animals, surface density only increased in animals treated with all-trans RA. Quantification of DNA content of basal keratinocytes showed reduction of 2C and 2C-4C populations with a commensurate increase in proportions of cells with 4C and > 4C in the animals treated with 0.025% all-trans RA and ROL. Suprabasal keratinocytes of mice treated with 0.025% all-trans showed a decrease of the 2C population and an increased proportion of cells with 4C. Whereas 0.025% all-trans RA induced an increase of both basal and suprabasal DNA indices, ROL enhanced only the basal DNA index significantly.

Conclusion: Animals treated with 0.025% ROL showed a significant increase in the basal proliferative index (PI) while the suprabasal PI remained constant; treatment with 0.025% all-trans RA produced a significant increase of both basal and suprabasal PIs and parakeratotic hyperkeratosis probably due to incomplete differentiation.

Immuno-gene therapy approaches for the treatment of malignant melanoma are categorized into two major subgroups according to an active or passive immunological principle. Active immuno-gene therapy is subdivided into melanoma cell vaccines, DNA-based vaccinations and the treatment of pre-existing tumor tissue by cell-mediated or direct transfer of cytokine and/or cell surface signal genes. Passive immuno-gene therapy, employing an adoptive treatment with in vitro activated and expanded anti-tumor effector cells, involves two major application fields for gene transfer techniques, first the genetic modification of the effector cells, and second the in vivo amplification of pre-effector cells by procedures also used in active immuno-gene therapy. Corresponding preclinical studies are reviewed. The clinical studies inaugurated during the last few years are mostly still ongoing and focus on treatment safety and tolerability rather than efficacy. A recent trend is emerging to explore recombinant adenovirus and vaccinia virus vectors particularly with regard to in vivo gene transfer applications. Overall, immuno-gene therapy of melanoma is still in a highly experimental stage of development but may become a safe, efficacious and practical adjuvant treatment modality in the future.

We measured the superoxide dismutase (SOD) activity in human skin from tissue homogenates after topical application of hydrocortisone-21-acetate and clobetasol proprionate, dissolved in propylene glycol. SOD was measured spectrophotometrically. SOD activity was higher in the treated skin than in the control untreated skin. We separated epidermis from the dermis by curettage and measured the level of SOD in each homogenized layer; SOD activity was higher in the epidermis compared to the dermis in untreated skin. After corticoid application, SOD activity was higher in the dermis compared to the epidermis to a degree dependent on corticoid potency. These experiments demonstrate that the epidermis may have a role in the barrier function of the skin by its antioxidant capacity and that the dermis is the major location of the metabolic activity in the skin. On the other hand, our results suggest that these corticosteroids may stimulate SOD production and may release antioxidants. This could be another anti-inflammatory property of corticosteroids.

Gene therapy approaches pursuing immunological strategies for the treatment of malignant melanoma play major roles in the current efforts to explore the potential benefits of gene transfer technologies for medicine. This may be explained by the nearly complete resistance of advanced metastatic melanoma towards conventional non-surgical treatment modalities, and the particular immunogenicity of melanoma in connection with a presumed immuno-gene therapeutic 'field effect'. The latter relates to the potency of the immune system to amplify gene transfer effects that are limited due to the imperfection of the currently available gene delivery systems. The ongoing clinical trials focus predominantly on treatment safety and tolerability rather than efficacy. The corresponding tumor-immunological background is reviewed, focusing on a treatment concept centred on tumor-reactive, cytotoxic CD8+ T effector cells.