Detection of monohydroxyeicosatetraenoic acids and F2-isoprostanes in microdialysis samples of human UV-irradiated skin by gas chromatography-mass spectrometry.

UV irradiation of the human skin leads to induction of oxidative stress and inflammation mediated by reactive oxygen radicals, lipid peroxidation, liberation of arachidonic acid from membrane phospholipids and formation of prostaglandins and leucotrienes. We investigated "lipid mediators", such as F(2)-isoprostanes (8-iso-PGF(2alpha), 9alpha,11alpha-PGF(2alpha)) and monohydroxyeicosatetraenoic acids (HETEs) in the dermal interstitial fluid obtained by a cutaneous microdialysis technique. Defined areas on the volar forearm of 10 healthy volunteers were exposed to UVB irradiation (20-60 mJ/cm(2)). Microdialysis membranes were cutaneously inserted beneath the irradiated area. The probes were perfused with isotonic saline solution, and microdialysate samples were collected at 20-min intervals up to 4-5 h. Oxidized arachidonic acid derivatives (2-, 3-, 5-, 8-12- and 15-HETEs, 8-iso-PGF(2alpha) and 9alpha,11alpha-PGF(2alpha)) could be detected and quantified in microdialysates of normal skin in the picomole (HETEs) and femtomole (isoprostanes) range and after UVB irradiation using sensitive gas chromatography-mass spectrometry/negative ion chemical ionization. UVB irradiation enhanced the levels of 8-iso-PGF(2alpha) after 24 h significantly, whereas the HETE levels were slightly increased within shorter time intervals (3 h after UVB irradiation). Further investigations have to show whether these new findings are relevant to validate therapeutic strategies for topical and systemic UV prevention agents or for monitoring of specific therapeutic strategies in inflammatory skin disorders.

Detection of enhanced monohydroxyeicosatetraenoic acid and F2-isoprostane levels in human plasma samples after extracorporeal photoimmunotherapy.

To investigate the involvement of reactive oxygen species in extracorporeal photoimmunotherapy (photopheresis), we have introduced two highly sensitive and specific techniques for the detection and quantitative measurement of oxygenated nonenzymatically formed arachidonic acid isomers [mono-hydroxyeicosatetraenoic acids (HETEs) and F2-isoprostanes] by gas chromatography-mass spectrometry/negative ion chemical ionization (GC-MS/NICI) in plasma samples of patients suffering from cutaneous T-cell lymphoma and progressive systemic scleroderma II. The analysis of HETEs involved hydrogenation, solid phase extraction on a C18 cartridge, formation of pentafluorobenzyl bromide and trimethylsilyl ether derivatives. In the case of F2-isoprostanes, the analytical procedure was similar to that of HETEs except that the hydrogenation step was omitted. In the plasma of healthy volunteers picomole amounts of 2-, 5-, 8-12-, 15-HETEs, 8-iso-PGF(2alpha) and 9alpha,11alpha-PGF(2alpha) were quantified by using 12-hydroxy-heptadecatrienoic acid and PGF(2alpha)-d4 as internal standards of HETEs and isoprostanes, respectively. Analysis of plasma samples obtained from patients before and after extracorporeal photoimmunotherapy revealed characteristic increases in both, HETE and isoprostane levels. The enhancement of indicators of lipid peroxidation is in correspondence with a moderate loss of alpha-tocopherol, the most important lipid-soluble antioxidant in human plasma. Thus, our data confirm the involvement of lipid peroxidation in extracorporeal photoimmunotherapy.

UV erythema reducing capacity of mizolastine compared to acetylsalicylic acid or both combined in comparison to indomethacin.

UV light exerts hazardous effects such as induction of skin cancer and premature skin aging. In this study we evaluated an assumptive anti-inflammatory effect of the nonsedative histamine H1-receptor antagonist, mizolastine, on UV-induced acute sunburn reaction. Therefore, a clinical, randomized, double-blind, four-arm, crossover study was conducted in healthy young female volunteers (skin type II) comparing the UV sensitivity under mizolastine, acetyl-salicylic acid (ASA), indomethacin or a mizolastine/ASA combination. Moreover, HaCaT keratinocytes were incubated with mizolastine under various UV treatment modalities in vitro to study its effect on the release of inflammatory cytokines, i.e. interleukin (IL)-1 alpha, IL-6 and tumor necrosis factor alpha (TNF-alpha). All three drugs were effective in suppressing the UVB-, UVA- and combined UVA/UVB-erythema. However, the strongest effects were observed using the combined treatment with both 250 mg ASA and 10 mg mizolastine. An inhibitory effect in vitro of 10 nM mizolastine upon UV-induced cytokine release from HaCaT keratinocytes was observed for IL-1 alpha at 24 h after 10 J/cm2 UVA1, for IL-6 at 48 h after 10 J/cm2 UVA1 and 30 mJ/cm2 UVB, and also for TNF-alpha at 4 h after 10 J/cm2 UVA, 10 J/cm2 UVA1 and 30 mJ/cm2 UVB, respectively. The combination of mizolastine and ASA can be strongly recommended as a protective measure against UV erythema development with a lower unwanted side effect profile than that of the hitherto treatment modality, i.e. indomethacin.

Extensive haemorrhagic-bullous skin manifestation of systemic AA-amyloidosis associated with IgGlambda-myeloma.

In an 86-year-old woman with a multiple myeloma of the IgG lambda subtype a coinciding systemic amyloidosis manifested as a macroglossia, diffuse alopecia and generalized cutaneous involvement. The skin was affected by milium-like papules, petechial haemorrhages and an increased tissue fragility with subsequent blister formation. The typical histology and immunohistology pattern revealed large intradermal amyloid masses, reacting positively with anti-amyloid A antibodies, which surrounded cuff-like dilatated blood capillaries. The abundance of these amyloid deposits led to significant deflexibilization and fragility of the capillaries and the dermal matrix eventually resulting in the haemorrhagic-bullous eruptions. The peculiar feature of the present case is the intensity of bullous-haemorrhagic skin damage due to amyloid A deposition without any detection of cutaneous IgGl as the myeloma-derived paraprotein assumed to be causative for the development of systemic AA amyloidosis.

[Prevention of ultraviolet ray damage: external and internal sunscreens]. / Präventivmassnahmen gegen UV-Lichtschäden: äusserer und innerer Lichtschutz.

Acute and chronic exposures to non-physiological doses of UV-light lead to a variety of changes of the skin. The most significant of these changes are a premature aging of the skin, UV-induced hyperkeratosis or atrophy, provocation of skin diseases and neoplasms of the skin. Furthermore, the local and systemic immune response can be negatively modulated. As long as society views tanned skin as a sign of beauty and success, and provided no behavioral changes occur, it will be required to emphasize prevention through education and the use of external and internal sun protection products. It is presently customary to use only sunscreens which can block UVB and UVA light to varying degrees. It could also be shown that presupplementation with beta carotene combined with topical sunscreens are more effective than sunscreen cream alone. Therefore the use of such a combination for the general health of population at risk e.g. before UV-exposure would seem advisable. There are no acceptable alternatives of protection against UV-radiation except suitable clothing and avoiding skin exposure to direct sun light.

Consequences of beta-glucocerebrosidase deficiency in epidermis. Ultrastructure and permeability barrier alterations in Gaucher disease.

Hydrolysis of glucosylceramide by beta-glucocerebrosidase results in ceramide, a critical component of the intercellular lamellae that mediate the epidermal permeability barrier. A subset of type 2 Gaucher patients displays ichthyosiform skin abnormalities, as do transgenic Gaucher mice homozygous for a null allele. To investigate the relationship between glucocerebrosidase deficiency and epidermal permeability barrier function, we compared the stratum corneum (SC) ultrastructure, lipid content, and barrier function of Gaucher mice to carrier and normal mice, and to hairless mice treated topically with bromoconduritol B epoxide (BrCBE), an irreversible inhibitor of glucocerebrosidase. Both Gaucher mice and BrCBE-treated mice revealed abnormal, incompletely processed, lamellar body-derived sheets throughout the SC interstices, while transgenic carrier mice displayed normal bilayers. The SC of a severely affected type 2 Gaucher's disease infant revealed similarly abnormal ultrastructure. Furthermore, the Gaucher mice demonstrated markedly elevated transepidermal water loss (4.2 +/- 0.6 vs < 0.10 g/m2 per h). The electron-dense tracer, colloidal lanthanum, percolated between the incompletely processed lamellar body-derived sheets in the SC interstices of Gaucher mice only, demonstrating altered permeability barrier function. Gaucher and BrCBE-treated mice showed < 1% and < 5% of normal epidermal glucocerebrosidase activity, respectively, and the epidermis/SC of Gaucher mice demonstrated elevated glucosylceramide (5- to 10-fold), with diminished ceramide content. Thus, the skin changes observed in Gaucher mice and infants may result from the formation of incompetent intercellular lamellar bilayers due to a decreased hydrolysis of glucosylceramide to ceramide. Glucocerebrosidase therefore appears necessary for the generation of membranes of sufficient functional competence for epidermal barrier function.

Evidence for a novel keratinocyte fatty acid uptake mechanism with preference for linoleic acid: comparison of oleic and linoleic acid uptake by cultured human keratinocytes, fibroblasts and a human hepatoma cell line.

Keratinocytes require the essential fatty acid (FA), linoleic acid (LA), for the synthesis of stratum corneum membrane lipids. A plasma membrane-FA binding protein (PM-FABP), is postulated to mediate cellular FA-uptake in hepatocytes and several other tissues, but the mechanism whereby exogenous FA are taken up by keratinocytes has not been investigated. This study examines the uptake of LA and oleic acid (non-essential) in cultured human keratinocytes, in comparison to dermal fibroblasts and the human hepatoma cell line, HepG2. As previously reported for hepatocytes, FA-uptake in keratinocytes was curvilinear, with an initial (30 s) rapid cellular influx. The initial uptake component was temperature dependent, exhibited saturable kinetics and was significantly inhibited by pretreatment with trypsin. In contrast, fibroblast FA-uptake lacked an initial rapid uptake component, was relatively temperature insensitive, and was not inhibited by trypsin. Keratinocytes differed from both hepatocytes and fibroblasts by more rapid uptake of LA in comparison to oleic acid during the initial influx phase. Moreover, FA-uptake in keratinocytes was not inhibited by preincubation with a anti-rat liver PM-FABP antibody. These data provide evidence for a PM-FA transporter in keratinocytes that is distinct from the hepatic PM-FABP. The apparent preference of the putative keratinocyte FA transporter for LA may function to ensure epidermal capture of sufficient LA for barrier lipid synthesis.