High iron and low ascorbic acid concentrations in the dermis of atopic dermatitis patients

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease in which reactive oxygen species (ROS) may be involved. Iron catalyses ROS formation and ascorbic acid (AA) scavenges these species. OBJECTIVE: The aim of this work was to determine iron and AA levels in AD patients' dermis and to compare their concentrations with those of healthy volunteers' dermis. METHODS: Five AD patients and 5 healthy subjects (controls) were enrolled in this study. Iron and AA were collected from human dermis by microdialysis and assessed by atomic absorption spectrometry and gas chromatography-mass spectrometry, respectively. RESULTS: The AD dermis demonstrated higher iron concentrations (44.3 +/- 4.6 microg/l) compared to controls (21.8 +/- 1.2 microg/l) as well as a significantly lower concentration of AA (46.7 +/- 0.6 vs. 176.8 +/- 14.5 microg/ml, respectively). CONCLUSION: These results suggest that iron and AA dermis levels could be indicators of inflammatory tissues and might be implicated in dermatological diseases such as AD.     

Evaluation of a sunscreen photoprotective effect by ascorbic acid assessment in human dermis using microdialysis and gas chromatography mass spectrometry

Ultraviolet irradiation causes adverse effects like sunburn, photosensitivity reactions or immunologic suppression. The aim of this study was to evaluate the photo-protective outcome of a sunscreen cream (SPF8) by the determination of erythema indexes and the assessment of ascorbic acid and its metabolites in human dermis. These substances were used as markers of oxidative effect. Eight healthy female subjects were enrolled in this study. Two abdominal areas were exposed to solar simulated irradiation with three minimal erythema dose, one with SPF8 application and the other site without SPF8 application. Two other areas were used as control, one without SPF8 application and the other site after SPF8 application. Ascorbic acid and its metabolites (dehydroascorbic acid, threonic acid, oxalic acid and xylose) were collected from human dermis by microdialysis and assessed by gas chromatography mass spectrometry. Irradiated site without sunscreen application had significantly demonstrated lower dermis ascorbic acid concentrations and a higher erythema index than the three other sites (P < 0.05). Threonic acid, oxalic acid and xylose dermis concentrations were significantly higher in site III than in the control site I (P < 0.05). The protected-irradiated site did not show erythema formation and there was stability of ascorbic acid dermis concentrations with non-variation in its metabolites. The assessment of ascorbic acid and its metabolites in human dermis could be an efficient tool to demonstrate the oxidative process and consequently to control the efficiency of sunscreen creams against undesirable UV effects.     

Selective decrease of 15-hydroxyeicosatetraenoic acid (15-HETE) formation in uninvolved psoriatic dermis

Epidermis of psoriatic skin lesions is characterized by elevated 5-lipoxygenase and 12-lipoxygenase products. 15-hydroxyeicosatetraenoic acid (15-HETE), the predominant lipoxygenase product in normal dermis, has the potential to inhibit 5-lipoxygenase and 12-lipoxygenase. The purpose of the present study was to determine the capacity of homogenized dermis from uninvolved psoriatic skin to form 15-HETE in vitro. Extracted lipids were separated by reversed-phase high-performance liquid chromatography. Each chromatographic peak was identified by its coelution with authentic standards, by ultraviolet spectrometry, and by radioimmunoassay. Dermis from uninvolved psoriatic skin generated on average 48% less 15-HETE than normal dermis (P less than .01). In contrast, the formation of 12-hydroxyeicosatetraenoic acid was increased by 56% in psoriatic dermis (P less than .01). Prostaglandin E2 formation was similar in normal and psoriatic dermis. Since 15-HETE can inhibit the synthesis of 5-lipoxygenase and 12-lipoxygenase products that possess inflammatory and proliferative capacities, a defective 15-HETE generation in dermis may be of importance for the development of psoriasis.     

In vivo percutaneous absorption of hydrocortisone in psoriatic patients and normal volunteers

Our objective was to determine the percutaneous absorption of hydrocortisone in psoriatic skin. [14C]-Hydrocortisone formulated as a 0.5% cream was applied to sharply defined erythematous plaques with silvery scales on the dorsal forearm of four hospitalized psoriatic patients. An average 2.32 +/- 1.4 (SD) percent of the applied dose was absorbed. The absorption of the same dose from the dorsal forearm of six normal subjects was 2.45 +/- 1.2%. We conclude that for presumably stable psoriatic plaques, the percutaneous absorption of hydrocortisone is the same as for normal skin.     

In vivo quantification of microvessels in clinically uninvolved psoriatic skin and in normal skin

BACKGROUND: Microvascular abnormalities (capillary elongation, widening and tortuosity) are a characteristic feature of psoriasis and form one of the pathological diagnostic criteria. However, it is still not entirely clear when these microcirculatory changes appear in the skin of psoriatic subjects. Some studies suggest that capillary dilatation and elongation are present in the clinically uninvolved skin of psoriatic patients even at sites at which psoriatic plaques rarely occur. OBJECTIVES: To determine, using noninvasive techniques in vivo, the nature of any microvascular changes in the clinically uninvolved skin of psoriatic subjects and to quantify the dermal microvasculature in the clinically uninvolved skin of psoriatic subjects, in vivo. METHODS: Dermal microvessels in both the clinically uninvolved skin of psoriatic subjects and in the skin of normal volunteers (i.e. individuals without any clinical evidence of psoriasis or other inflammatory dermatoses) were directly visualized by native video-capillaroscopy, in vivo. Images were analysed using a combination of nonstereological and stereological measurements. The findings in each group were then compared to determine if there were any differences in microvascular parameters. RESULTS: Quantitative analysis of capillaroscopic images showed that there were no significant differences in microvessel density (P = 0.9), image area fraction (P = 0.6), microvessel length density (P = 0.7) and vessel image width (P = 1.0) in the clinically uninvolved skin of psoriatic subjects and the normal skin of healthy volunteers, when extensor forearm skin was examined. CONCLUSIONS: These findings indicate that prior to the development of clinical lesions there are no significant morphological differences between the dermal microvessels in the clinically uninvolved skin of psoriatic subjects and the dermal microvessels in the normal skin of healthy volunteers. However, during plaque formation, the superficial papillary microvessels in plaque skin undergo a striking, characteristic change, i.e. elongation, widening and tortuosity. These blood vessels must therefore, at least in part, play an important, necessary, but probably secondary role in the pathogenesis of clinical lesions in psoriasis.     

In vivo measurement of the water content in the dermis by confocal Raman spectroscopy

Background/purpose: Dermal water plays an important role in the physical properties of the skin. Recently, researchers have attempted to directly measure the dermal water content in vivo using magnetic resonance imaging, near infrared spectroscopy, and Raman spectroscopy. However, these methods have limitations. Although confocal Raman spectroscopy has been developed to measure the water content in the skin, no reports have suggested that this instrument can measure the dermal water content. This report describes a method for measuring the dermal water content in vivo using confocal Raman spectroscopy. Methods: We used a confocal Raman spectrometer and adjusted the laser exposure time and depth increments according to the skin depth. Age‐related changes in the dermal water content of the forearm were examined in 30 young and 30 elderly male subjects. Diurnal changes in the dermal water content of the forearm were examined in 12 elderly male subjects. Results: Adjusting the exposure time and depth increment dramatically improved the signal‐to‐noise ratios of the Raman spectra. Elderly dermis had significantly higher water content than young dermis. Moreover, the dermal water content displayed a diurnal change. Conclusion: This study demonstrates that the dermal water content can be measured in vivo using confocal Raman spectroscopy.     

In vivo measurement of human dermis by 1064 nm-excited fiber Raman spectroscopy.

BACKGROUND/AIMS: Although chemical information on the dermis in vivo is highly important in skin research, an efficient method for gathering this information is yet to be developed. Here, we demonstrate that newly developed near-infrared (1064 nm) excited Raman spectroscopy is a powerful method for chemical analysis of human skin in vivo. METHODS: We used a laboratory-constructed Raman spectrometer equipped with a highly sensitive near-infrared detector (Hamamatsu Photonics), an optical fiber probe and a 1064 nm Nd:YAG laser. Raman spectra of porcine skin (in vitro) and human skin (in vivo) were measured with this spectrometer. RESULTS: The Raman spectrum of porcine skin measured from the outer side resembles that of the dermis more than that of the epidermis. The Raman spectra of human skin (cheek, forehead, inner forearm, outer forearm, palm) depend on the portion measured with the probe. The spectra of the forehead and inner forearm show larger lipid signals than that of the palm. CONCLUSIONS: The Raman spectrum of skin measured with the 1064 nm Raman system primarily reflects the chemical composition of the dermis. The 1064 nm excited Raman spectroscopy is useful for research of the dermis and skin appendages.     

银屑病患者与正常人表皮和真皮的cAMP与cGMTP含量及其意义

本文报告了用放射免疫分析法测定31例银屑病患者和27例正常人的表皮和真皮的环化核普酸含量.还测定其中6例银屑病患者治愈后表皮环化核苷酸含量.     

In vivo hydration and water-retention capacity of stratum corneum in clinically uninvolved skin in atopic and psoriatic patients

Hydration and the water-retention capacity of stratum corneum have been investigated in uninvolved psoriatic and atopic skin and compared with that of healthy controls. Thirty-three subjects of either sex and matched for age entered the study. The subjects were free from all signs of skin disease and skin dryness. Hydration was evaluated by means of transepidermal water loss and skin capacitance measurements. Water-retention capacity was investigated using the plastic occlusion stress test. Atopic skin differed significantly from uninvolved psoriatic and control skin which had a reduced water content and an increased transepidermal water loss. Furthermore, the skin surface water loss profile representing the stratum corneum water-retention capacity was significantly lower in normal atopic skin. The data suggest that clinically normal skin may be functionally abnormal, resulting in a defective barrier that could lead to higher risk of irritant or contact dermatitis.     

In vivo quantification of the structural abnormalities in psoriatic microvessels before and after pulsed dye laser treatment

BACKGROUND: Microvascular abnormalities (capillary elongation, widening and tortuosity) are a characteristic feature of psoriasis and form one of the pathological diagnostic criteria. These changes occur early in the progression of a psoriatic plaque, before there is clinical or histological evidence of epidermal hyperplasia. Treatment of psoriatic microvessels with a pulsed dye laser (PDL) has been associated with both clinical improvement and clearance of lesions. OBJECTIVES: To quantify the structural vascular abnormalities in plaque skin using noninvasive techniques in vivo. Investigations were carried out before and after PDL treatment to determine the nature of laser-induced microvascular changes and the relationship between these changes and clinical improvement. METHODS: Plaque microvessels were visualized using native capillaroscopy. Plaques were then treated three times with the PDL at 14-day intervals. Native capillaroscopy was repeated at 2 and 6 weeks after the final laser treatment. Images were analysed using a combination of nonstereological and stereological measurements. RESULTS: Whole body disease was stable. Treated plaques showed a 48% reduction in plaque severity score (P < 0.01). Native studies showed that the PDL significantly reduced plaque microvessel density (P < 0.05), image area fraction (P < 0.01), microvessel length density (P < 0.01) and vessel image width (P < 0.01). The reduction in plaque severity score (which denoted clinical improvement) was related quantitatively to the reduction in microvessel area per unit area of plaque skin, i.e. the image area fraction (correlation coefficient = 0.772, P < 0.01). The greatest response of plaque microvessels was within 2 weeks after the final laser treatment, while the greatest reduction in plaque severity score occurred between 2 and 6 weeks after the final laser treatment, i.e. clinical improvement was preceded by microvascular improvement. CONCLUSIONS: These findings indicate that there is a close correlation between the state of the superficial vasculature and the clinical status of psoriasis. The expanded superficial microvascular bed in plaque skin is a necessary component for maintaining clinical lesions and these blood vessels are thus a legitimate target for treatment.     

Psoriasiform architecture of murine epidermis overlying human psoriatic dermis transplanted onto SCID mice

Preliminary observations in a xenogeneic SCID mouse transplantation model indicated that murine epidermis overgrows human dermis from psoriatic skin but not that form normal skin. To investigate the effect of peripheral blood mononuclear cells on the differentiation of murine keratinocytes, we transplanted involved and uninvolved full-thickness skin from patients with psoriasis onto SCID mice and followed this with repeated subcutaneous injections of cells suspended in patient serum. After 6 weeks grafts were analysed morphologically and immunohistochemically. The epidermis in grafts from clinically uninvolved skin appeared normal. The persistence of a psoriasiform epidermis was noted in all grafts from affected sites despite a lack of lymphocytic infiltration. Staining for human and mouse MHC class I antigens revealed the murine origin of keratinocytes forming the psoriasiform epidermis, while the human dermis was retained. Our observations indicate that the defect underlying the pathogenesis of psoriasis is most likely located in the dermal rather than the epidermal compartment. This xenogeneic transplantation model may be useful for future studies of the pathogenesis and treatment of psoriasis.     

In situ localization of interferons in psoriatic lesions

Summary An indirect immunofluorescence technique, using murine monoclonal antibodies (MoAbs) against human IFN- and human IFN- was used to study IFNs in cryostat sections from psoriatic skin lesions. The IFNs were more pronounced in sections from highly active psoriasis than in sections from stationary psoriasis. In highly active psoriatic lesions IFNs- was localized to keratinocytes in stratum basale, to some epidermal dendritic cells, probably Langerhans cells, and to some mononuclear cells in dermis. IFN- was usually not detected in sections from stationary psoriasis. IFN- was localized to stratum corneum, to keratinocytes around microabcesses and to mononuclear cells in the dermal cell infiltrates, predominantly in highly active psoriatic lesions. Both IFN- and IFN- were localized to some endothelial cells in the papillary dermis. The MoAbs did not stain sections from unaffected skin from patients with psoriasis or sections from healthy individuals. The findings indicate that the IFN system in the skin may be of significance in the pathophysiology of psoriasis.     

In vivo quantification of epidermis pigmentation and dermis papilla density with reflectance confocal microscopy: variations with age and skin phototype

Reflectance confocal microscopy (RCM) may help to quantify variations of skin pigmentation induced by different stimuli such as UV radiation or therapeutic intervention. The objective of our work was to identify RCM parameters able to quantify in vivo dermis papilla density and epidermis pigmentation potentially applicable in clinical studies. The study included 111 healthy female volunteers with phototypes I-VI. Photo-exposed and photo-protected anatomical sites were imaged. The effect of age was also assessed. Four epidermis components were specifically investigated: stratum corneum, stratum spinosum, basal epidermal layer and dermo-epidermal junction. Laser power, diameter of corneocytes and upper spinous keratinocytes, brightness of upper spinous and interpapillary spinous keratinocytes, number of dermal papillae and papillary contrast were systematically assessed. Papillary contrast measured at the dermo-epidermal junction appeared to be a reliable marker of epidermis pigmentation and showed a strong correlation with skin pigmentation assessed clinically using the Fitzpatrick's classification. Brightness of upper spinous and interpapillary spinous keratinocytes was not influenced by the skin phototype. The number of dermal papillae was significantly lower in subjects with phototypes I-II as compared with darker skin subjects. A dramatic reduction in the number of dermal papillae was noticed with age, particularly in subjects with fair skin. The method presented here provides a new in vivo investigation tool for quantification of dermis papilla density and epidermal pigmentation. Papillary contrast measured at the dermo-epidermal junction may be selected as a marker of skin pigmentation for evaluation in clinical studies.