Reverse iontophoresis: monitoring prostaglandin E2 associated with cutaneous inflammation in vivo

Abstract In response to topical application of irritants, increased concentrations of prostaglandin E₂ (PGE₂) are found in human skin exudate and in cultured dermal fibroblasts. In this study, PGE₂ generated in response to transdermal delivery of irritant drug compounds was monitored in hairless guinea pig (HOP) by a non-invasive method, reverse iontophoresis. Reverse iontophoresis is the movement of molecules from the skin under the influence of an applied electric field. Irritant drug compounds were applied with iontophoresis (electrotransport), and reverse iontophoresis of PGE₂ from skin was monitored by radioimmunoassay (RIA) after extraction from the delivery system. Chlorpromazine was used as a model drug irritant. When chlorpromazine and saline were applied over a range of current densities from 0 to 200 μA/cm², visual scores of erythema and edema yielded a correlation with measured skin efflux of PGE₂ (r=0.86). Delivery of chlorpromazine resulted in greater efflux of PGE₂ than delivery of non-irritant saline controls under the same delivery conditions. Five drug compounds, chloroquine, promazine, chlorpromazine, tetracaine, metoclopramide, and saline were applied to hairless guinea pig skin. The 6 agents were similarly rank ordered by visual erythema/edema scores and by PGE₂ efflux, indicating that the quantity of PGE₂ effluxed reflects the intensity of skin irritation. In contrast, vasoconstriction or vasodilation produced by the local delivery of vasoactive agents did not correlate with PGE₂ skin efflux, indicating that this measurement is specific for an inflammatory response. In summary, PGE₂ generated in response to transdermally applied drug irritants can be monitored non-invasively in vivo by reverse iontophoresis.     

Role of the vitamin D3 pathway in healthy and diseased skin – facts, contradictions and hypotheses

Abstract: Irradiation of human keratinocytes with UVB (280–320 nm) in vitro and in vivo activates the metabolism of 7‐dehydrocholesterol to hormonally active calcitriol. The production of calcitriol in the skin strongly depends on the photosynthesis of vitamin D₃ which is biologically inactive in the first instance. Vitamin D₃ serves as the starting substrate for two subsequent enzymatic hydroxylation steps in epidermal keratinocytes. Both the amount of vitamin D₃ and the activity of anabolic and catabolic vitamin D hydroxylases determine the cutaneous level of calcitriol. The hormonally active metabolite of vitamin D₃ regulates a huge number of genes in keratinocytes, and thus acts in an autocrine and/or paracrine manner. This local pathway of vitamin D₃ is unique, but its relevance for healthy and diseased skin is widely unknown, yet. Experimental findings implicate several questions: ( 1 ) Is UVB‐induced formation of calcitriol involved in regulation of growth and differentaition of epidermal cells as well as immunological and skin protective processes? ( 2 ) What endogenous and exogenous factors including drugs affect the cutaneous vitamin D₃ pathway? From a therapeutical point of view, it has been known for a long time that topical application of calcitriol and its analogs can improve hyperproliferative skin diseases like psoriasis. In spite of many encouraging studies in recent years, the fields of the routinely therapeutical application of calcitriol or vitamin D analogs in dermatology (e.g. treatment of immunological, inflammatory, malignancies and infectious skin diseases) have not been intensified. Why is that?     

Histamine H2-receptor antagonists inhibit enzymic histamine degradation in human skin

The histamine H₂-receptor antagonists burimamide and cimetidine cause inhibition of human skin histamine-N-methyl transferase (HMT) in the dose range 10^-3–10^-4 M. Amodiaquin, a recognized inhibitor of animal HMT, also produced dose-related inhibition of human HMT. These findings may explain the observation that H₂-receptor antagonists enhance certain types of inflammatory response in skin.     

Scleromyxoedema (lichen myxoedematosus) associated with a paraprotein, IgG1 of type kappa

A case of scleromyxoedema (lichen myxoedematosus) associated with an IgG₁, type kappa paraproteinaemia is reported. Culture of bone marrow material demonstrated that this tissue synthesized monoclonal IgG (subclass γ I) with a light chain of type kappa. The culture of a biopsy specimen of the diseased skin demonstrated low-speed IgG synthesis. It is concluded that the bone marrow and pathological skin synthesize a paraprotein with the same characteristics as that in the serum. Microchemical analysis of pathological skin demonstrated an increase in the content of neutral glycoproteins, hyaluronic acid and chondroitin sulphates as well as the presence of heparin and keratan sulphates. It could not be demonstrated that the serum of this patient contained antibody against connective tissue ground substance or other skin constituents.     

CO2 laser debridement of sulphur mustard (bis-2-chloroethyl sulphide) induced cutaneous lesions accelerates production of a normal epidermis with elimination of cytological atypia

Sulphur mustard (bis-2-chloroethyl sulphide: HD) exposure acutely produces lesions that vary from mild erythema, to blister formation, to necrosis. When blisters occur, with or without necrosis, healing of the lesions is delayed. Weanling pigs exposed to a mild erythema-producing dose of HD and to a moderate erythema-producing dose that consistently gave microblister formation were treated with CO₂ (Tru-Pulse) debridement at 6, 24 or 48 h after exposure. The histopathological features observed at 14 days after exposure in control skin and skin exposed to both HD doses were compared with the features observed in CO₂ laser-debrided skin in non-exposed and HD-exposed skin sites. The overlying epidermis in the non-laser treated lesions was thin, with cytological atypia and squamoid changes within the basal cell layer, as well as scattered apoptotic/necrotic keratinocytes. An increased inflammatory infiltrate and necrobiotic changes in the dermis were seen at the higher HD dose. All laser-treated lesions appeared identical, with a thick, differentiated epidermis and a well-formed basal cell layer. There was minimal inflammatory infiltrate. In the papillary dermis there were increased stromal cells. Laser debridement of mild clinical lesions induced by HD produced a more functional epidermis by 14 days as well as clearing the epidermis of damaged keratinocytes. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army, the Department of the Navy, or the Department of Defense.     

Abnormal expression of interleukin-23 in mycosis fungoides/Sézary syndrome lesions

Progression of mycosis fungoides (MF) to Sézary syndrome (SS) is accompanied by a shift from a T_H1 to a T_H2 cytokine profile. Interleukin (IL)-23 is a novel cytokine that shares a common p40 subunit with the T_H1 inducer, IL-12. IL-23 induces a third profile, T_HIL-17, that is dominant in inflammation and autoimmunity. Although IL-23 induces an eczematous-like skin reaction in mice, and is expressed in T_H1-mediated skin disorders such as psoriasis, it has not been evaluated in MF/SS. To study the role of IL-23 in MF/SS development, 40 MF/SS lesions of all stages were immunohistochemically analyzed with a novel anti-human IL-23 antibody raised against full-length human IL-23. IL-23 was detected with the catalyzed signal amplification system. The intensity and frequency of IL-23 staining were semi-quantitatively graded in both the dermal infiltrate and the epidermis. Increased expression of IL-23 was observed throughout the epidermal keratinocytes and in dermal lymphocytes compared to normal skin. IL-23 intensity did not differ significantly among the stages of MF/SS; however, in stage IVB patients, we observed lower frequency of IL-23 expression in dermal lymphocytes than in other stage patients [P = 0.13, analysis of variance (ANOVA)]. Interestingly, clusters of atypical lymphocytes, especially the epidermotropic tumor cells, demonstrated weak or absent IL-23 staining in 18 of 40 (45%) lesions. This finding was present in 4 of 5 (80%) of the stage IVB lesions and 7 of 11 (64%) of the lesions from Sézary patients. These findings indicate that abnormal IL-23 expression may play a role in the pathogenesis and progression of MF/SS.     

Lichenoid skin lesions as a sign of β2-microglobulin-induced amyloidosis in a long-term haemodialysis patient

We report a case of β₂-microglobulin-induced amyloidosis. The patient was a 40-year-old man suffering from non-amyloid nephropathy, who had been treated by haemodialysis for 20 years. Lichenoid skin lesions, consisting of groups of pin-head-sized shiny papules, were present on the arms and trunk. On histological examination, amyloid deposits were present, principally in the dermal papillae, hut also around the sweat ducts and hair follicles. The amyloid displayed potassium-permanganate-resistant Congo red affinity, and green birefringence under polarized light, Immuno-histochemically, β₂-microglobulin was demonstrated in the lesions, confirming that they were a manifestation of β₂-microglobulin-associated amyloidosis. Skin lesions of this type have not been reported previously in β₂-microglobulin-associated amyloidosis.     

COMPARATIVE STUDY OF WOUND HEALING IN PORCINE SKIN WITH CO2 LASER AND OTHER SURGICAL MODALITIES: PRELIMINARY FINDINGS

Background. The CO₂ laser is a common surgical modality in dermatology. To clarify conflicting reports on the histological healing properties of CO₂ laser on incisional or ablative wounds, we have applied it in a miniature hairless porcine skin model at power settings similar to those used in clinical practice. Methods. Histological parameters of wound healing in skin incisions using the CO₂ laser were compared with those using scalpel, hot scalpel, and electrosection, and in dermal ablation using CO₂ laser, fraize, wire brush, and electrofulguration alone or with curettage. Results. In incisional wounds, tissue damage was most extensive in CO₂ laser wounds, with delayed dermal healing and reepithelialization. In ablative wounds, CO₂ laser caused a similar degree of tissue damage as did the electrosurgical modalities, and more damage than did fraize or wire brush. Reepithelialization was complete in CO₂ laser, fraize, and wire brush wounds before electrosurgical wounds. Final histology of both incisional and ablative wounds at 6 weeks was similar with all surgical modalities. Conclusion. The CO₂ laser and electrosurgery both produce greater focal tissue damage in incisional and ablative applications than the other modalities. Delayed epithelialization of the wound occurs with both modalities in incisional wounds but only with electrosurgery in ablative wounds. At 6 weeks, the appearance of the scar in all incisional and ablative modalities is similar grossly and histologically. Confirmation of these findings requires standardization of power density of the CO₂ laser in incision and ablation.     

Bleomycin‐induced fibrosis in MC1 signalling‐deficient C57BL/6J‐Mc1re/e mice further supports a modulating role for melanocortins in collagen synthesis of the skin

The melanocortin‐1 receptor (MC₁) binds α‐melanocyte‐stimulating hormone (α‐MSH) with high affinity and has a physiological role in cutaneous melanin pigmentation. Previously, we reported that human dermal fibroblasts also express functional MC₁. α‐MSH suppressed transforming growth factor‐β₁‐ and bleomycin (BLM)‐induced collagen synthesis in vitro and in vivo. Using MC₁ signalling‐deficient C57BL/6J‐Mc1r^e/e mice, we tested as to whether MC₁ has a regulatory role on dermal collagen synthesis in the BLM model of scleroderma. Notably, mice with a C57BL/6J genetic background were previously shown to be BLM‐non‐susceptible. Interestingly, treatment of C57BL/6J‐Mc1r^e/e but not of C57BL/6J‐wild‐type mice with BLM increased cutaneous collagen type I content at RNA and protein level along with development of skin fibrosis. Cutaneous levels of connective tissue growth factor and monocyte chemotactic protein‐1 were also increased in BLM‐treated C57BL/6J‐Mc1r^e/e mice. Primary dermal fibroblasts from C57BL/6J‐wt mice further expressed MC₁, suggesting that these cells are directly targeted by melanocortins to affect collagen production of the skin. Our findings support the concept that MC₁ has an endogenous regulatory function in collagen synthesis and controls the extent of fibrotic stress responses of the skin.     

Efficacy of the continuous use of a lotion with carbon dioxide on male subjects with mild acne

Objective

Acne vulgaris is caused by dyslipidemia, dyskeratosis and/or abnormal bacterial growth. The obstruction of skin pores due to hyperkeratosis of the infundibulum contributes to the formation of comedones. Thus, normalizing keratinization of epidermal cells in skin pores might be useful to improve acne. Recently, it has been found that the transcutaneous application of carbon dioxide (CO₂) regulates imbalances of the desquamatory process. In this study, we evaluated the efficacy of a skin lotion containing CO₂ on mild acne.

Methods

Twenty-four healthy Japanese males (20–29 years old) with mild acne attended this evaluation. The subjects were divided into 2 groups, one group used a skin lotion containing CO₂ and the other group used a skin lotion without CO₂. Following facial washing, each subject topically applied the skin lotion with or without CO₂ twice a day for 4 weeks. Prior to the start of the evaluation (week 0) and following 2 and 4 weeks of treatment, acne symptoms were assessed by a dermatologist and by instrumental measurements.

Results

Topical application of the skin lotion with CO₂ for 4 weeks significantly improved acne symptoms, which was recognized by the subjects. However, treatment with the skin lotion without CO₂ did not improve acne symptoms. This improvement of acne symptoms by CO₂ was not accompanied by changes in sebum levels, skin surface pH, skin capacitance, or porphyrin levels.

Conclusion

The transcutaneous application of a lotion with CO₂ improves acne symptoms by normalizing keratinization without affecting skin surface conditions.     

Subchronic exposure of titanium dioxide nanoparticles to hairless rat skin

The evaluation of the biological effects of industrial nanoparticles on the skin is necessary for their risk assessment. To clarify the influence of TiO₂ nanoparticles on the skin, we carried out a subchronic exposure study of TiO₂ nanoparticles to hairless rat skin. W/O emulsion containing 10 wt% TiO₂ nanoparticles and control emulsion was applied to the dorsal skin of Hairless Wistar Yagi rats once a day for a maximum period of 56 consecutive days. After 2, 4 and 8 weeks, skin samples were taken from the exposed skin area. Histopathologically, the particles were only located in the stratum corneum layer of epidermis and follicular epithelium. Focal parakeratosis and spongiosis were observed in the epidermis. Transmission electron microscopy with energy‐dispersive X‐ray spectrometry (EDX) analysis failed to show TiO₂ nanoparticles in the viable skin areas. There was no evidence of TiO₂ penetration in the viable skin areas. In addition, titanium contents in several organs were determined using inductively coupled plasma mass spectroscopy. Increased titanium concentration was detected in lung samples of the TiO₂ emulsion‐treated groups after 8 weeks. It was most likely that the presence of TiO₂ in the lungs was not caused by direct absorption of nanoparticles from the skin but was due to rats inhaling the nanoparticle. We did not find any obvious evidences of nano‐TiO₂ particle skin penetration using several morphological methods after the subchronic exposure. We believe that the influence of subchronic exposure of TiO₂ is not significant based on our study.     

RANTES expression in psoriatic skin, and regulation of RANTES and IL-8 production in cultured epidermal keratinocytes by active vitamin D3 (tacalcitol)

The chemokine RANTES is a chemoattractant for eosinophils, T lymphocytes of memory phenotype and monocytes, suggesting that it plays an important part in chronic inflammatory and allergic diseases. In various types of cells, RANTES production is markedly induced by tumour necrosis factor (TNF)-α and interferon (IFN)-γ in combination. Psoriasis vulgaris is a chronic cutaneous inflammatory disease. Cytokines and chemokines produced by T cells and epidermal keratinocytes, such as interleukin (IL) 8, are involved in the pathogenesis of psoriasis. T-cell clones obtained from psoriatic skin have been shown to produce the Th1 cytokine IFN-γ. In addition, abnormal expression of proinflammatory cytokines including TNF-α has been observed in psoriatic lesions. These reports led us to hypothesis that psoriatic skin could provide epidermal keratinocytes with TNF-α and IFN-γ, so that keratinocytes could produce RANTES. In this study, we addressed the question as to whether RANTES was involved in psoriasis vulgaris. Immunohistochemistry of skin biopsies showed RANTES was present in the intercellular spaces between epidermal keratinocytes, in the fully developed lesions from the middle to the edge of psoriatic plaques, but not in the perilesional uninvolved and healthy control skin. Further, we confirmed the production of RANTES, together with IL-8, by cultured normal human epidermal keratinocytes, using an enzyme-linked immunosorbent assay. Stimulation with TNF-α and IFN-γ in combination synergistically increased the RANTES production in this system. These results clearly demonstrate the expression of RANTES in psoriatic lesions and suggest the involvement of this chemokine in the outcome of cutaneous inflammatory diseases. Tacalcitol (1α,24(R)-dihydroxyvitamin D₃), an active vitamin D₃ analogue, inhibited RANTES and IL-8 production in cultured normal epidermal keratinocytes. This result indicates that active vitamin D₃ is effective in the regulation of chemokine production by epidermal keratinocytes, which may partly account for its action as an antipsoriatic drug.     

Blockade by polyphloretin phosphate of the prostaglandin E1-induced human cutaneous reaction

The effect of polyphloretin phosphate (PPP) on the human cutaneous reaction induced by prostaglandin E₁ (PGE₁) has been studied in thirty subjects. Pre-treatment of the skin with three intradermal injections of 1oo μg PPP reduced by 37% the magnitude of the erythema induced by intradermal injection of 1 μg PGE₁. The PGE₁induced weal, which is probably mainly due to PGE₁-induced endogenous histamine release, was not reduced. The specific nature of the PG-blocking activity of PPP was supported, since PPP did not block the erythema and weal induced by intradermal injection of histamine and bradykinin. Intravenous injection of 100 mg PPP did not reduce the erythema due to intradermal injection of PGE₁ probably because of too low tissue concentration of PPP.     

Imiquimod‐induced skin inflammation is relieved by knockdown of sodium channel Nax

Na_x is an atypical sodium channel that mediates inflammatory pathways in pathological conditions of the skin. In this study, we developed a skin inflammation model in the rabbit ear through application of imiquimod (IMQ). Knockdown of Na_x using RNAi attenuated IMQ‐induced skin inflammation, including skin erythema, scaling and papule formation. Histologic analysis showed that thickening and insufficient differentiation of the epidermis found in psoriasis‐like skin were normalized by administration of Na_x‐RNAi. Excessive infiltration of inflammatory cells found in inflammatory lesions, such as mast cells, eosinophils, neutrophils, T cells and macrophages, was reduced by Na_x‐RNAi. Expression of S100A9, which is a downstream gene of Na_x and a mediator of inflammation, was decreased by Na_x‐RNAi. Our results demonstrated that knockdown of Na_x ameliorated IMQ‐induced psoriasis‐like skin inflammation in vivo. Thus, targeting of Na_x may represent a potential therapeutic option for the treatment of psoriasis.     

Vitamin D3 levels and bone mineral density in patients with psoriasis and/or psoriatic arthritis

Limited data are available on the vitamin D₃ status and bone mineral density (BMD) of patients with psoriasis or with psoriatic arthritis. Our study intended to explore possible correlations between vitamin D status and BMD, as well as among these parameters and the features of the underlying disorder. Seventy‐two patients with psoriasis/or psoriatic arthritis (female : male ratio, 40:32; mean age, 58.5 ± 11.6 years; mean duration of follow up, 142.7 ± 147.7 months) participated in the study. We evaluated the characteristic clinical features of the underlying disease, performed bone densitometry of the lumbar spine and the hip region, measured the serum vitamin 25(OH)D₃ levels of the patients, and undertook the statistical analysis of the relationships between the clinical and the laboratory parameters. The proportion of patients with a low BMD value did not exceed that seen in the general population. We found an inverse correlation between the serum level of vitamin 25(OH)D₃ and body mass index, as well as between the former and the severity of skin involvement. Furthermore, the activity of psoriatic arthritis was significantly higher in patients with inadequate vitamin D₃ status. In patients with psoriatic arthritis, BMD significantly exceeded the values measured in patients suffering from psoriatic skin lesions only. Our findings suggest the importance of evaluating the vitamin D₃ status and screening for comorbid conditions in patients with psoriasis or psoriatic arthritis. This appears justified, in particular, due to the possible role of hypovitaminosis D₃ in provoking the development of skin lesions and joint symptoms.     

Age-related changes in the elastic properties and thickness of human facial skin

Using recently designed, commercially available, non-invasive instruments, we measured the thickness and elasticity of the skin of the face and ventral forearm in 170 women, and evaluated the effects of age and exposure to sunlight. Skin thickness decreased with age in ventral forearm skin, which has limited exposure to sunlight, but increased significantly in the skin of the forehead, corners of the eyes, and cheeks, which are markedly exposed to sunlight. Skin elasticity (U_r/U_f) decreased with age on both the face and forearm. The ratio of viscosity element to elasticity element (U_v/U_e) increased with age at all sites. However, delayed distension (U_v), immediate retraction (U_r), final distension (U_f), and immediate distention (U_e), as individual elements, decreased on the face and increased on the forearm with age. This tendency was more marked after correction for skin thickness. These results suggested the specificity of skin thickness and elasticity in the facial skin. Analysis using a four-element model showed no changes in the elasticity coefficient of Maxwell element on the forearm, but an increase on the face. This indicates quantitative or qualitative changes in elastic fibres in facial skin. Thus, sunlight appears to have a considerable effect on the thickness and physical properties of facial skin.     

Efficacy and safety evaluation of an innovative CO2 laser/radiofrequency device in dermatology

Background CO₂ laser has not only become the most widely used laser in dermatological surgical practice, but it has also proved to be highly effective in treating aesthetic imperfections. Objective To examine the efficacy and safety of a novel fractional CO₂ laser combined with a radiofrequency device in different dermatological, surgical and aesthetic fields. Methods A total of 79 patients were treated in our Outpatient Service with a novel fractional CO₂ laser combined with a bipolar radiofrequency device for a maximum of 5 months. Group A consisted of 39 patients with lesions requiring complete excision, whereas Group B consisted of 40 subjects seeking to enhance aesthetic facial imperfections. The results were assessed by three ‘blind’ investigators using photographs and clinical observations; in addition, the patients had to give their own subjective assessment of the results. Results At the 6‐month follow‐up, the lesions of the Group A patients had been completely removed, except for one case of a large sebaceous nevus on the scalp. All the Group B patients showed global improvement in skin tightening, removal of fine lines and rhytides and correction of dilated pores and hyperpigmentation, with no significant side‐effects and short downtimes. Conclusion This kind of laser meets the needs of the majority of dermatologists requiring a unique, versatile tool to remove cutaneous lesions and at the same time, safely and effectively treat skin imperfections.     

Effect of parent genetic background on latency and antigenicity of UV-induced tumors originating in F1 hybrids

Abstract Wide variations in susceptibility to skin tumor development by chronic ultraviolet light (UV) exposure and antigenicity of induced tumors which is estimated by tumor rejection in syngeneic recipients have been recognized among various murine strains. To examine the effect of parent genetic background on latency and antigenicity of UV-induced tumors originating in F₁ hybrids, we induced skin tumors in three mouse strains: BALB/c, C57BL/6, (B6), and C3H/HeMs (C3H/He), and their F₁, hybrids: (BALB/c×C3H/He)F₁, (CC3F₁), (BALB/c×B6)F₁, (CB6F₁) and (C3H/He×B6)F₁, (C3B6F₁) by exposing mice to UV radiation (0.44 mW/ cm² for 1 h) three times a week, and analyzed whether the UV-induccd tumors originating in F₁ hybrids possess the similar property in latency or antigenicity as seen in the UV-induced tumors derived from the parent strains. The latency of tumor induction by chronic UV exposure in C3H/He, BALB/c and their F₁, hybrid CC3F₁, was relatively short whereas that of B6 was relatively long, and that of F₁, hybrids with B6 (CB6F, and C3B6F₁) was intermediate. On the other hand, the low antigenicity as progressive growth behavior of UV-induced tumors in syngeneic recipients was observed not only in tumors derived from C3H/He but also in those from F, hybrids with C3H/He (C3B6F₁, and CC3F₁) whereas most tumors derived from B6, BALB/c and their F₁ hybrid CC3F₁ were highly antigenic as to be rejected in syngeneic recipients. These findings suggest that the parent genetic quality regulating the susceptibility to tumor induction by chronic UV exposure is co-dominantly inherited into F₁ hybrids. On the other hand, that providing the progressive growth behavior of induced tumors appears to be a dominant effect.