Eradication of skin microbiota restores cytokine production and release in polymorphic light eruption

Polymorphic light eruption (PLE) has been mechanistically linked to cytokine abnormalities. Emerging preclinical evidence posits the skin microbiome as a critical modulator of ultraviolet (UV)-induced cytokine expression, thereby influencing subsequent immune responses. This intricate relationship remains underexplored in the context of PLE. Hence, we investigated the differential responses between disinfected and non-disinfected skin following both single and repetitive exposures to solar-simulated UV radiation in patients with PLE. An experimental, half-body pilot study was conducted involving six PLE patients and 15 healthy controls. Participants' skin was exposed to single and multiple doses of solar-simulated UV radiation, both in disinfected and in non-disinfected skin areas. The co-primary outcomes were PLE score and cytokine expression in blister fluid analysed through OLINK proteomic profiling. Secondary outcomes were erythema, pigmentation, induction of apoptotic cells in vacuum-generated suction blisters, and density of infiltrate in skin biopsies of PLE patients. Among the 71 cytokines analysed, baseline expression levels of 20 specific cytokines-integral to processes such as apoptosis, inflammation, immune cell recruitment, cellular growth, and differentiation-were significantly impaired in PLE patients compared with healthy controls. Notably, skin disinfection reversed the observed cytokine imbalances following a single UV exposure at the minimal erythema dose (MED) level and exhibited even more pronounced effects after multiple UV exposures. However, no significant differences were evident in PLE score, erythema, pigmentation, or rates of apoptotic cell induction upon UV radiation. These findings provide evidence for UV-driven cytokine regulation by the skin microbiota and imply microbiome involvement in the PLE immune response.

Drug triggered pruritus, rash, papules, and blisters - is AGEP a clash of an altered sphingolipid-metabolism and lysosomotropism of drugs accumulating in the skin?

Rash, photosensitivity, erythema multiforme, and the acute generalized exanthematous pustulosis (AGEP) are relatively uncommon adverse reactions of drugs. To date, the etiology is not well understood and individual susceptibility still remains unknown. Amiodarone, chlorpromazine, amitriptyline, and trimipramine are classified lysosomotropic as well as photosensitizing, however, they fail to trigger rash and pruritic papules in all individuals. Lysosomotropism is a common charcteristic of various drugs, but independent of individuals. There is evidence that the individual ability to respond to external oxidative stress is crosslinked with the elongation of long-chain fatty acids to very long-chain fatty acids by ELOVLs. ELOVL6 and ELOVL7 are sensitive to ROS induced depletion of cellular NADPH and insufficient regeneration via the pentose phosphate pathway and mitochondrial fatty acid oxidation. Deficiency of NADPH in presence of lysosomotropic drugs promotes the synthesis of C16-ceramide in lysosomes and may contribute to emerging pruritic papules of AGEP. However, independently from a lysosomomotropic drug, severe depletion of ATP and NAD(P)H, e.g., by UV radiation or a potent photosensitizer can trigger likewise the collapse of the lysosomal transmembrane proton gradient resulting in lysosomal C16-ceramide synthesis and pruritic papules. This kind of papules are equally present in polymorphous light eruption (PMLE/PLE) and acne aestivalis (Mallorca acne). The suggested model of a compartmentalized ceramide metabolism provides a more sophisticated explanation of cutaneous drug adverse effects and the individual sensitivity to UV radiation. Parameters such as pKa and ClogP of the triggering drug, cutaneous fatty acid profile, and ceramide profile enables new concepts in risk assessment and scoring of AGEP as well as prophylaxis outcome.

Brown-gray hyperpigmentation in a photosensitive distribution after levofloxacin exposure

Photosensitive drug reactions resulting in hyperpigmentation occur when there is an accumulation in the skin of melanin, heavy metals, or the drug itself. Herein we describe an immunocompromised orthotopic liver transplant patient with levofloxacin-induced hyperpigmentation with iron deposition. To identify the causal agent, consideration was given to medications the patient had taken long-term, as well as medications introduced more recently before the event. Levofloxacin and posaconzole emerged as the most likely culprit drugs, neither of which have a strong history in the literature of being associated with photosensitive hyperpigmentation. Levofloxacin was determined to be the culprit drug when the hyperpigmentation gradually resolved several weeks after discontinuation of levofloxacin, with continuation of posaconazole and all other long-term medications. This case highlights the challenges in identifying the causal agent in photosensitive drug reactions when patients are taking multiple medications. Key clinical data can be very helpful in making an assessment.

Expression of E-cadherin, syndecan 1, Ki-67, and maintenance minichromosome 3 in tissue lesions of actinic prurigo obtained by incisional biopsy

Actinic prurigo (AP) is an idiopathic photodermatosis; the initial manifestations usually occur during the first decades of life but can appear at any age. Cases are usually diagnosed late once the lesions have exacerbated; due to the extensive involvement of the vermilion border and the etiology, it has been confused with and related to a potentially malignant process. Syndecan-1 and E-cadherin were positive in the epidermis, with moderate-to-intense staining in 100% of samples. Ki67 and MCM3 were expressed in the lower third of the epidermis and showed greater immunolabeling in samples that contained lymphoid follicles (Ki 67: epidermis [17.7% ± 6.79%] and dermis [7.73% ± 6.69%]; MCM3: epidermis [22.92% ± 10.12%] and dermis [6.13% ± 6.27%]). In conclusión AP is a disease in which there is no evidence that the lesions are potentially cancerous. AP cheilitis should not be confused with actinic cheilitis because they are separate entities.

Disturbed iron metabolism in erythropoietic protoporphyria and association of GDF15 and gender with disease severity

Patients with erythropoietic protoporphyria (EPP) have reduced activity of the enzyme ferrochelatase that catalyzes the insertion of iron into protoporphyrin IX (PPIX) to form heme. As the result of ferrochelatase deficiency, PPIX accumulates and causes severe photosensitivity. Among different patients, the concentration of PPIX varies considerably. In addition to photosensitivity, patients frequently exhibit low serum iron and a microcytic hypochromic anemia. The aims of this study were to (1) search for factors related to PPIX concentration in EPP, and (2) characterize anemia in EPP, i.e., whether it is the result of an absolute iron deficiency or the anemia of chronic disease (ACD). Blood samples from 67 EPP patients (51 Italian and 16 Swiss) and 21 healthy volunteers were analyzed. EPP patients had lower ferritin (p = 0.021) and hepcidin (p = 0.031) concentrations and higher zinc-protoporphyrin (p < 0.0001) and soluble-transferrin-receptor (p = 0.0007) concentrations compared with controls. This indicated that anemia in EPP resulted from an absolute iron deficiency. Among EPP patients, PPIX concentrations correlated with both growth differentiation factor (GDF) 15 (p = 0.012) and male gender (p = 0.015). Among a subgroup of patients who were iron replete, hemoglobin levels were normal, which suggested that iron but not ferrochelatase is the limiting factor in heme synthesis of individuals with EPP.

MICRORNAS AS ULTRAVIOLET IRRADIATION EFFECTS REGULATORS IN SKIN CELLS

MicroRNAs belong to small non-coding RNA which regulate gene expression via mRNA degradation or translation inhibition. MicroRNAs are active modulators of gene expression in the skin caused by exogenous factors including ultraviolet irradiation. These effects are realized by targeting transcription factors and signaling systems components. Changes in microRNAs levels started to register in a few hours after exposure to ultraviolet irradiation, wich confirms the presence of an effective fast processes in the scin cells that modulate the functional status of microRNAs. The reported recently ability of microRNAs to be transported by exosomes may be related to systemic effects of ultraviolet irradiation that include the altered immune response and systemic inflammatory reaction. Understanding these processes is important because of the possibility of purposeful influence on the expression and activity of a microRNA that may have implications for diagnosis and therapy of photodermatosis and malignant skin tumors.

Photosensitive human syndromes

Photosensitivity in humans can result from defects in repair of light-induced DNA lesions, from photoactivation of chemicals (including certain medications) with sunlight to produce toxic mediators, and by immune reactions to sunlight exposures. Deficiencies in DNA repair and the processing of damaged DNA during replication and transcription may result in mutations and genomic instability. We will review current understanding of photosensitivity to short wavelength ultraviolet light (UV) due to genetic defects in particular DNA repair pathways; deficiencies in some are characterized by an extremely high incidence of cancer in sun-exposed tissues, while in others no cancers have been reported.

Protein oxidation and DNA repair inhibition by 6-thioguanine and UVA radiation

Damage to skin DNA by solar UV is largely unavoidable, and an optimal cellular response to it requires the coordinated operation of proteins in numerous pathways. A fully functional DNA repair proteome for removing harmful DNA lesions is a prerequisite for an appropriate DNA damage response. Genetically determined failure to repair UV-induced DNA damage is associated with skin photosensitivity and increased skin cancer risk. Patients treated with immunosuppressant/anti-inflammatory thiopurines are also photosensitive and have high rates of sun-related skin cancer. Their DNA contains the base analog 6-thioguanine (6-TG), which acts as a UVA photosensitizer to generate reactive oxygen species (ROS), predominantly singlet oxygen ((1)O2). ROS damage both DNA and proteins. Here we show that UVA irradiation of cultured human cells containing DNA 6-TG causes significant protein oxidation and damages components of the DNA repair proteome, including the Ku, OGG-1, MYH, and RPA proteins. Assays of DNA repair in intact cells or in cell extracts indicate that this protein damage compromises DNA break rejoining and base and nucleotide excision repair. As these experimental conditions simulate those in the skin of patients taking thiopurines, our findings suggest a mechanism whereby UVA in sunlight may contribute to skin carcinogenesis in immunosuppressed patients.

Impaired secondary oxidant deactivation capacity and enhanced oxidative stress in serum from alveld affected lambs

Alveld is a hepatogenous photosensitivity disorder in lambs. The aim of the study was to investigate if alveld affected lambs had a reduced capacity to handle oxidative stress induced from either endogenous and/or exogenous photosensitizers. Serum samples from alveld lambs (n=33) were compared to serum samples from control lambs (n=31) and exposed to a controlled amount of singlet oxygen ((1)O2). The sera from alveld lambs were found to have an impaired ability to deactivate reactive oxygen species (ROS) compared to control sera. A higher degree of initial hemolysis and a higher concentration of the exogenous photosensitizer phytoporphyrin (PP) were detected in alveld sera compared to the controls. The action spectrum for the formation of (1)O2 indicated that PP as well as the endogenous compound protoporphyrin IX (PP IX) may act as in vivo photosensitizers. A relatively high level of iron was detected in pooled serum from alveld lambs that showed a high degree of hemolysis. It was concluded that alveld photosensitivity is likely to be initiated by a photodynamic reaction involving PP and possibly also PP IX followed by a light-independent reaction involving hemoglobin-related products and catalysis by the Fenton reaction.

Kindlin-1 regulates integrin dynamics and adhesion turnover

Loss-of-function mutations in the gene encoding the integrin co-activator kindlin-1 cause Kindler syndrome. We report a novel kindlin-1-deficient keratinocyte cell line derived from a Kindler syndrome patient. Despite the expression of kindlin-2, the patient’s cells display several hallmarks related to reduced function of β1 integrins, including abnormal cell morphology, cell adhesion, cell spreading, focal adhesion assembly, and cell migration. Defective cell adhesion was aggravated by kindlin-2 depletion, indicating that kindlin-2 can compensate to a certain extent for the loss of kindlin-1. Intriguingly, β1 at the cell-surface was aberrantly glycosylated in the patient’s cells, and its expression was considerably reduced, both in cells in vitro and in the patient’s epidermis. Reconstitution with wild-type kindlin-1 but not with a β1-binding defective mutant restored the aberrant β1 expression and glycosylation, and normalized cell morphology, adhesion, spreading, and migration. Furthermore, the expression of wild-type kindlin-1, but not of the integrin-binding-defective mutant, increased the stability of integrin-mediated cell-matrix adhesions and enhanced the redistribution of internalized integrins to the cell surface. Thus, these data uncover a role for kindlin-1 in the regulation of integrin trafficking and adhesion turnover.

[Photodynamic effect on cells of human adipose tissue in vitro]

Changes in optical properties of human adipose tissue cells after photodynamic exposure in vitro were found and investigated. Analysis of the kinetics of the process was realized by means of photomicrography of the object investigated. The statistical computer processing of digital photos obtained gave us an opportunity to estimate quantitatively the kinetics of photodynamic effect upon the tissue. Optical interpretation of the photos obtained indicates that the observed phenomenon corresponds to the partial lysis of adipose tissue cells without their complete destruction.

Hereditary photodermatoses

Photodermatoses are defined as the abnormal reactions of the skin to photons, usually those of wavelengths found in sunlight. These reactions can be caused by a wide variety of reasons, including defects in repair oflight-induced DNA lesions, the interaction of certain chemicals or medications with sunlight to produce toxic mediators and photo-induced immune reactions. In this chapter we will describe photodermatoses that are associated with hereditary conditions. These can be subdivided into several groups: dermatoses caused by abnormal metabolic conditions, idiopathic photodermatoses, defects in cancer suppressor genes not directly involved in DNA repair but that predispose to photodistributed tumors and photosensitivity due to abnormalities in DNA repair pathways. Special emphasis will be placed on the relatively recently described UV-sensitive syndrome.

The versatile DNA nucleotide excision repair (NER) and its medical significance

Two of DNA's worst enemies, ultraviolet light and chemical carcinogens, can cause damage to the molecule by mutating individual nucleotides or changing its physical structure. In most cases, genomic integrity is restored by specialized suites of proteins dedicated to repairing specific types of injuries. One restoration mechanism, called nucleotide excision repair (NER), recruits and coordinates the services of 20-30 proteins to recognize and remove structure-impairing lesions, including those induced by ultraviolet (UV) light. Mutations in a gene that encodes a protein from the NER machinery might cause a wide variety of rare inherited human disorders. Sun sensitivity, cancer, developmental retardation, neurodegeneration and premature aging characterize these syndromes. Identification of the causative genes and proteins in affected families in Israel allowed us to establish accurate molecular diagnosis of couples at risk, and provide them with better genetic counseling.

[Expressions of fibrillin-1, elastin and matrix metalloproteinase-1 and -9 in chronic actinic dermatitis in elderly patients]

To investigate the expressions of fibrillin-1, elastin and matrix metalloproteinase-1 and -9 (MMP-1, 9) in chronic actinic dermatitis in elderly patients and explore the pathogenesis of the disease.

METHODS

Twenty-three patients with chronic actinic dermatitis were examined for the expressions of fibrillin-1, elastin, MMP-1, and MMP-9 with immunohistochemistry in the skin lesions. Image analysis was carried out to measure MMP-1 and MMP-9 expressions semi-quantitatively.

RESULTS

In the skin lesions of patients with chronic actinic dermatitis, elastin expression was obviously reduced or absent in the papillary dermis. The elastic fibers were disorderly arranged in the reticular dermis with local aggregation in some regions. Obvious fibrillin-1 deposition was found in the reticular dermis. Increased expressions of MMP-1, but not that of MMP-9, was found in the skin lesions of the patients.

CONCLUSION

Elastin and fibrillin-1 deposition can be found in the skin lesions in patients with chronic actinic dermatitis, suggesting the association of increased MMP-1 expression with the elastic tissue degeneration in the lesions. MMP-9 does not exhibit an obvious association with the pathogenesis of chronic actinic dermatitis in elderly patients.

Signal transducer and activator of transcription-3 expression and activation is dysregulated in actinic cheilitis

BACKGROUND

The present study evaluates the signal transducer and activator of transcription-3 (STAT-3) expression and activation in actinic cheilitis (AC) and the relationship of this protein with the degree of epithelial dysplasia.

METHODS

Twenty-five cases of AC were analyzed. Normal lip mucosa was used as a control group. AC lesions were graded as mild, moderate and severe dysplasias. Immunohistochemistry for STAT-3 and phospho-STAT-3 (STAT-3P) was performed using the biotin-streptavidin-peroxidase method, and the sections were evaluated by three blinded examiners.

RESULTS

In normal lip mucosa, only cytoplasmic expression of STAT-3 was observed in the basal and parabasal layers. In AC, STAT-3 was expressed in the cell cytoplasm of the epithelial layers, except in the superficial layer. Nuclear expression of STAT-3 in occasional basal and parabasal cells was seen in moderate and severe dysplasias. In normal lip mucosa, nuclear expression of STAT-3P was found throughout the epithelium, except in the superficial layers, and it was more intense in the deeper layers. In AC, STAT-3P was also expressed in all layers, except for the superficial layer. However, in moderate and severe dysplasias, some epithelial cells exhibited loss of STAT-3P expression.

CONCLUSION

In AC, STAT-3 expression depends on the degree of dysplasia, and STAT-3 activation is dysregulated compared with normal tissue.

Expression of apoptotic, cell proliferation regulatory, and structural proteins in actinic keratosis and their association with dermal elastosis

BACKGROUND

Actinic keratosis (AK) is a premalignant lesion caused by ultraviolet (UV) radiation and characterized by epithelial and connective tissue alterations. However, little is known about the link between connective and UV-damaged epithelial tissues in AK.

OBJECTIVE AND METHODS

To examine the potential relationship between connective tissue degeneration and molecular alterations in epithelial cells without evident morphologic changes, 30 cases of AK (8, grade I; 10, grade II; 12, grade III), divided into three grades according to the proportion of dermal elastosis (in grade I, up to 30% of collagen degeneration; in grade II, 30-60%; in grade III, more than 60%), were immunohistochemically analyzed for the expression of Ki67, p53, p63, bcl-2, E-cadherin, 34-betaE12, and CD99.

RESULTS

The increase in the solar elastosis grade was associated with an increase in positive cell numbers for all analyzed markers. Basal expression predominated in the lesions with low and moderate levels of connective tissue degeneration, while a basal and suprabasal expression pattern was prevalent in the lesions with high degeneration. In grade I and II lesions, proliferation marker, Ki67, expression was found to be significantly associated with the proapoptotic marker p53, while in grade III lesions, its expression was correlated with the anti-apoptotic marker, bcl-2.

CONCLUSIONS

These results demonstrate that the epithelial expression of apoptotic, cell proliferation, and structural proteins is augmented with the increase of the solar elastosis grade. Thus, the grade of solar elastosis could be a helpful morphologic marker in the assessment of neoplastic changes in sun-damaged skin.

[Trichothiodystrophy: PIBIDS syndrome]

Trichothiodystrophy comprises a heterogeneous group of autosomal recessive entities. This fact gives rise to different interrelated neuroectodermal disorders. From a structural point of view these features are the result of the low tissue sulfur content. We report a case of trichothiodystrophy initially classified as Tay syndrome that based on clinical features, complementary exams as well as on the disease evolution was labelled as PIBIDS syndrome.

Plasmacytoid dendritic cells are absent in skin lesions of polymorphic light eruption

BACKGROUND/PURPOSE

Polymorphic light eruption (PLE) is a common photodermatosis of potential autoimmune origin, and an overlap with lupus erythematosus (LE) has been described. Plasmacytoid dendritic cell (PDC)-induced expression of interferon (IFN)-alpha has been found to be present in LE skin lesions and plays a pivotal role in the pathogenesis of LE by promoting autoimmunity. We therefore asked whether PDCs may also be involved in the pathogenesis of PLE and searched for those cells [which can be identified by their high levels of interleukin (IL)-3 receptor alpha chain (CD123), combined with other cell markers such as CD68] in skin lesions.

METHODS

Paraffin-embedded biopsy specimens from a total of 27 patients with clinically and histologically confirmed PLE (nine women, mean age 32.7 years, age range 18-43), LE (seven women, four men, CCLE: n=4, SCLE: n=2, lupus tumidus: n=5, mean age 48.5 years, age range 41-65) or psoriasis (four women, three men, mean age 43.3 years, age range 19-54) (as control group) were analyzed by immunohistochemical CD68/CD123 double staining. Quantification of the immunohistochemical staining was performed by visual cell counting of CD68-/CD123+, CD68+/123-, and CD68+/CD123+ cells separately in the epidermis and dermis of the samples in at least 10 random fields per sample at x 400 microscopic magnification by two of the investigators in a blinded fashion.

RESULTS

Microscopic examination of the immunohistochemically stained sections revealed that CD68+/CD123+ cells were present in most specimens obtained from LE [10/11 (91%)] and psoriasis [6/7 (86%)] patients but not at all in those obtained from PLE patients. Quantification and statistical analysis of the dermal infiltrate revealed that CD68+/CD123+ cells were present at a mean+/-SEM field density of 5.6+/-1.3 in LE, 1.6+/-0.6 in psoriasis but totally absent in PLE (P=0.0010 vs. LE, P=0.0135 vs. psoriasis by an unpaired Student's t-test).

CONCLUSION

The results confirm the potential significance of PDCs in LE and psoriasis, however the absence of PDCs in PLE contradicts the hypothesis that these cells might play a role in the latter disease.

Biochemical abnormality in erythropoietic protoporphyria: cause and consequences

OBJECTIVES

Erythropoietic protoporphyria (EPP) is a genetic disorder in which deficient ferrochelatase (FECH) activity causes the excessive production and excretion of protoporphyrin. This in turn causes the major clinical manifestation of EPP, photosensitivity and, in some patients, hepatobiliary disease that may be severe. The objective of this study was to define genotypic determinants of phenotype in EPP.

METHODS

FECH activity was measured in 30 tissue samples from 26 patients with symptomatic EPP to determine the degree of deficient activity. FECH DNA analysis was also done in 26 families with EPP to identify mutations and examine for the presence of a polymorphism (IVS3-48c) that causes low gene expression.

RESULTS

The level of residual FECH activity that was measured in tissue samples of patients with symptomatic EPP was <or=30% of the mean normal level in all patients except one. Lowest levels (4-20% normal) were in patients with advanced EPP liver disease. Heterozygous FECH mutations were found in 45 individuals from 26 families with EPP. In 94% of the 32 symptomatic individuals, 15 of whom had liver disease, the polymorphism was present in the nonmutant allele. In 13 asymptomatic patients, the polymorphism was absent.

CONCLUSIONS

Patients with symptomatic EPP (photosensitivity with/without hepatobiliary disease) usually have a mutation in 1 FECH allele that alters enzyme structure/function, together with a polymorphism in the nonmutant allele that causes low gene expression. This leads to a significant reduction in FECH activity that causes symptomatic disease to develop because of the excess protoporphyrin produced.

Impaired removal of 8-hydroxydeoxyguanosine induced by UVB radiation in naevoid basal cell carcinoma syndrome cells

BACKGROUND

The naevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by tumorigenesis such as multiple basal cell carcinomas, odontogenic keratocysts and developmental abnormalities such as calcified dural folds and rib-anomalies. Recently, it has been shown that ultraviolet (UV) B exposure produced more BCCs in ptch knockout mice than wild mice.

OBJECTIVES

To Investigate the role of UV in development of BCCs in NBCCS, cellular sensitivity to killing by UVB and removal of UVB-induced oxidative DNA damage were examined using fibroblasts derived from patients with NBCCS under physiologically relevant doses of UVB exposure.

PATIENTS AND METHODS

Three patients with NBCCS, a 59-year-old male patient, an 18-year-old boy and a 13-year-old boy were examined by photobiological analysis. Cellular sensitivity to killing by UVB and UVC and removal of oxidative DNA damage caused by UVB were tested using fibroblasts derived from these patients. We measured cellular 8-hydroxydeoxyguanosine (8-OHdG) after UVB exposure up to 24 h after UVB exposure using high-performance liquid chromatography.

RESULTS

All three cell strains derived from the patients with NBCCS were hypersensitive to killing by UVB (D10: 50-70% of normal) but not by UVC. After UVB exposure, the production of 8-OHdG increased dose dependently up to 3200 J m-2 in both NBCCS cells and normal cells. In normal cells, 8-OHdG after UVB exposure returned to its basal level during 24 h, whereas in NBCCS cells the amount of 8-OHdG after 800 J m-2 of UVB exposure did not return to its basal level even after 24 h. The result indicates the removal of 8-OHdG could be impaired in NBCCS cells. Ability in removal of thymine dimers of NBCCS cells was similar to that of normal cells.

CONCLUSIONS

Hypersensitivity to UVB can be one of the diagnostic tools of NBCCS for those whose clinical features have not yet completed. Hypersensitivity to cell killing and the impairment of removal of 8-OHdG after UVB exposure may play some role in developing BCCs and other tumours in NBCCS.

Role of p38 MAPK in UVB-Induced Inflammatory Responses in the Skin of SKH-1 Hairless Mice

The p38 mitogen-activated protein kinase (MAPK) signaling pathway is activated by numerous inflammatory mediators and environmental stresses. We assessed the effects of ultraviolet B (UVB) on the p38 MAPK pathway and determined whether cyclooxygenase (COX)-2 expression is downstream of this kinase in the skin of UVB-irradiated SKH-1 mice. SKH-1 mice were irradiated with a single dose of UVB (360 mJ per cm2), and activation of the epidermal p38 MAPK pathway was assessed. UVB-induced phosphorylation of p38 MAPK occurred in a time-dependent manner. Phosphorylation of MAPK-activated protein kinase-2 (MAPKAPK-2) also was detected and correlated with an increase in its kinase activity. Phosphorylation of heat shock protein 27 (HSP27), a substrate for MAPKAPK-2, also was detected post-irradiation. Oral administration of the p38 inhibitor, SB242235, prior to UVB irradiation, blocked activation of the p38 MAPK cascade, and abolished MAPKAPK-2 kinase activity and phosphorylation of HSP27. Moreover, SB242235 inhibited expression of the pro-inflammatory cytokines interleukin (IL)-6 and KC (murine IL-8) and COX-2. Our data demonstrate that UVB irradiation of murine skin activates epidermal p38 MAPK signaling and induces a local pro-inflammatory response. Blockade of the p38 MAPK pathway may offer an effective approach to reducing or preventing skin damage resulting from acute solar radiation.

Prevention of murine erythropoietic protoporphyria-associated skin photosensitivity and liver disease by dermal and hepatic ferrochelatase

Erythropoietic protoporphyria (EPP) is caused by a defect in ferrochelatase, leading to the accumulation of protoporphyrin predominantly in erythrocytes and hepatocytes, and resulting in skin photosensitivity upon leaching of blood protoporphyrin into the skin. Some patients also develop severe liver damage. Because the respective contributions of hepatic and erythrocytic protoporphyrin to the pathophysiology of EPP remain unclear, we investigated this question using the murine model of EPP. Transplantation of bone marrow from EPP mice to normal recipients resulted in elevated erythrocyte and plasma protoporphyrin levels. However, quantification of serum liver enzymes and bilirubin together with histopathologic examination of liver sections of mice up to 16 months post-transplantation showed no evidence of liver damage. Moreover, despite massive elevation of serum protoporphyrin, transplanted mice showed minimal evidence of skin photosensitivity. Photosensitivity could also be prevented locally by implanting skin grafts from normal mice onto the backs of EPP recipients. These data validate the hypothesis that the main source of toxic protoporphyrin originates from the erythrocytes. However, we unexpectedly observed that normal ferrochelatase activity in hepatic and dermal cells of wild-type mice is sufficient to prevent liver disease and significant skin photosensitivity. These findings may provide new strategies for the treatment of EPP.

Expression of the peripheral benzodiazepine receptor is decreased in skin cancers in comparison with normal skin

BACKGROUND

The peripheral benzodiazepine receptor (PBR) is an 18-kDa protein receptor mainly found on the outer mitochondrial membrane of cells. The PBR plays a role in several cellular functions including haem synthesis, steroidogenesis, DNA synthesis, cell growth and differentiation, and apoptosis. PBR expression in normal skin correlates with proliferating, secretory and differentiated cellular structures. Increased or aberrant expression of PBR has been associated with aggressive behaviour in several tumour types including ovarian, colon and breast adenocarcinomas and glioblastoma.

OBJECTIVES

To determine whether changes in normal PBR distribution would be useful as markers for skin cancers or possible target sites for therapies such as photodynamic therapy (PDT), we used immunohistochemistry to evaluate PBR expression and distribution in normal and photodamaged skin (actinic keratoses), skin cancers (in situ and invasive squamous cell carcinomas and superficial, nodular, morphoeiform and mixed pattern basal cell carcinomas) and several benign epithelial proliferations.

METHODS

A rabbit polyclonal antibody to a synthetic peptide fragment of the PBR was developed and characterized by enzyme-linked immunosorbent assay and Western blot analysis. The antibody was used to stain formalin-fixed and paraffin-embedded tissue samples (n = 157) by a routine avidin-biotin immunohistochemical technique. Sections were evaluated for antibody localization, distribution (0-4+) and reaction intensity (negative to strong).

RESULTS

Normal skin stained with a strong homogeneous positive reaction (3-4+) in the spinous and granular layers (with a gradient corresponding to increasing differentiation), the pilosebaceous units, eccrine gland ducts, endothelial cells and pilar muscle. In cutaneous neoplasms and other skin diseases, a heterogeneous pattern (0-4+) of PBR expression at lower intensity was seen depending on tumour type and degree of differentiation. PBR expression was greatest in well-differentiated tumours, synonymous with the PBR expression gradient seen in normal skin; and least in poorly differentiated and infiltrative tumour types.

CONCLUSIONS

The haem biosynthetic pathway has been harnessed for PDT of skin carcinomas by application of exogenous aminolaevulinic acid to generate the endogenous photosensitizer protoporphyrin IX (PpIX). Owing to the role of PBR as a transporter of haem precursors in haem synthesis, PBR density and distribution in skin cancers could be a predictor of the capacity for PpIX production and subsequent response to PDT in skin cancers.

Characterization of tiger tail banding and hair shaft abnormalities in trichothiodystrophy

BACKGROUND

Tiger tail banding under polarizing light microscopy and hair shaft abnormalities are associated with trichothiodystrophy (TTD), a rare disorder with a wide spectrum of clinical presentations.

OBJECTIVE

To characterize the frequency, specificity, and extent of tiger tail banding and hair shaft abnormalities in the spectrum of TTD patients.

METHODS

We developed a standardized procedure for microscopic hair examination and studied hairs from 14 TTD and 4 xeroderma pigmentosum (XP)-TTD patients for tiger tail banding and hair shaft abnormalities. For comparison we examined hairs from 173 control donors consisting of 15 normals, 13 XP patients, 11 family members of XP or TTD patients, 101 patients with various cornification disorders, and 33 leukodystrophy patients. Amino acid analysis performed on hair from the TTD and XP-TTD patients showed low sulfur content.

RESULTS

Using a rotating microscope stage, all hairs in each TTD sample showed tiger tail banding under polarized light in association with a variety of hair shaft abnormalities (trichoschisis, trichorrhexis nodosa-like defects, surface irregularities, and ribboning). None of the control hairs showed tiger tail banding, and 5 of 173 controls had weathering hair shaft abnormalities.

CONCLUSIONS

In patients with clinical features suggestive of TTD, tiger tail banding seen in all hairs with polarizing microscopy, in conjunction with certain hair shaft abnormalities, provides a reliable diagnostic test.

[Non-melanocytic dischromias]

Non-melanocytic hyperpigmentations (dyschromias), besides common melanotic ones, develop mostly due to the skin reaction to various chemicals and/or drugs of exogenous origin. They can be however also caused by some endogenously formed (evolving) intermediates of several metabolic diseases. The above mentioned factors are of toxic or allergic character and their clinical dermal manifestation often occurs as an allergic reaction after the exposition of the skin to solar radiation, or as a toxic contact reaction both on the skin and the mucosa. As a therapy of individual skin changes is difficult or impossible, the only treatment consists in reliable photoprotective measures.

Vascular endothelial growth factor promotes sensitivity to ultraviolet B-induced cutaneous photodamage

Acute ultraviolet B (UVB) irradiation of the skin results in erythema, vasodilation, edema, and angiogenesis, which is associated with the expression of vascular endothelial growth factor (VEGF) by epidermal keratinocytes. It is unclear, however, whether VEGF is required for the damage or repair process that occurs in the skin on UVB exposure. We subjected transgenic mice that overexpress VEGF, and their wild-type littermates, to graded doses of acute UVB irradiation. The skin of VEGF-overexpressing mice was highly photosensitive and became erythematic when exposed to half the UVB dose required to induce erythema in wild-type mice. Erythema was associated with proliferating dermal endothelial cells, cutaneous edema, and inflammatory cell infiltration. When subjected to 10 weeks of low-level UVB irradiation, no major changes were observed in wild-type mice, whereas VEGF transgenic mice developed skin damage associated with degradation of the dermal matrix and enhanced vascularization. Systemic treatment with an anti-VEGF blocking antibody reduced the sensitivity of wild-type mice to acute UVB irradiation without inhibiting post-UVB repair. Our results reveal that VEGF promotes the cutaneous damage that occurs after UVB exposure and that the VEGF signaling pathway might serve as a novel target for the prevention of UVB-induced photodamage.

Immunohistochemical study of chronological and photo-induced aging skins using the antibody raised against D-aspartyl residue-containing peptide

BACKGROUND

Biologically uncommon D-aspartyl residues have been reported in the elderly tissues such as tooth, eye lens, aorta, and brain. We have previously prepared the antibody against D-aspartyl residue-containing peptide and found that it reacted with elastotic material of actinic elastosis.

METHODS

Immunoreactivity of the normal skins obtained from sun-exposed and sun-protected skins of varied ages with this antibody was studied.

RESULTS

In the sun-exposed skins, the antibody showed negative reaction with the skin specimens of young donors, whereas it reacted with elastotic materials of actinic elastosis of the elderly. In the sun-protected skins, the antibody recognized elastic fiber-like structures and inner layer of vessels found from the mid to lower dermis of old donors but showed no positive reaction to skin specimens of young donors.

CONCLUSIONS

The results suggest that the antibody is a potent marker for chronological and ultraviolet (UV)-induced skin aging. Unusual eosinophilic bodies seen in the superficial dermis in the sun-exposed area of the elderly skins were also immunoreactive with the antibody, suggesting that the eosinophilic bodies resulted from UV-induced skin damage.

P27 and mib1 expression in actinic keratosis, Bowen disease, and squamous cell carcinoma

The histologic boundary between actinic keratosis, Bowen disease, and invasive squamous cell carcinoma is not clear in many cases. We determined nuclear expression of p27 (a protein associated with cellular quiescence) and Ki-67 (a marker of proliferation) immunohistochemically in actinic keratosis, Bowen disease, and squamous cell carcinoma to see if differential patterns of expression for p27 exist and how these might correlate with Ki-67 expression. We determined a labeling index for p27-stained nuclei and assessed the pattern of Ki-67 expression. The student's t test was used to evaluate the p27 labeling index. The p27 labeling index was decreased in invasive aggregates of squamous cell carcinoma (76.9+/- 1.1%) when compared with those of normal epidermis (97.2+/- 2.4%), actinic keratosis (95.3 +/- 1.4%), and Bowen disease (98.0+/- 0.5%). Ki-67 was expressed in a scattered to confluent linear pattern in the basal/parabasal cell layer of normal epidermis and actinic keratosis. Keratinocytes in squamous cell carcinoma exhibited Ki-67 in the peripheral layers of the neoplasm and frequently within the tumor aggregates. Ki-67 was observed in nuclei throughout the full thickness of the epidermis in Bowen disease. The staining pattern of Ki-67 in Bowen disease separated this entity from others under study. The combination pattern of p27 and Ki-67 staining can be used to support differentiation of actinic keratosis, Bowen disease, and squamous cell carcinoma.

Human papillomavirus infection in actinic keratosis and bowen’s disease: comparative study with expression of cell-cycle regulatory proteins p21waf1/cip1, p53, pcna, ki-67, and bcl-2 in positive and negative lesions

We examined the presence of human papillomavirus (HPV) DNA in tissues of premalignant skin lesions, i.e., actinic keratosis (n = 13) and Bowen's disease (n = 62), taken from 69 Japanese immunocompetent and renal transplant recipient patients. Detection and typing of HPV DNA were performed using polymerase chain reaction (PCR) and sequence analysis or restriction fragment length polymorphism (RFLP) analysis, respectively. The positivity rates of HPV DNA in tissues of actinic keratosis and Bowen's disease were 77% and 65%, respectively. Twenty-seven HPV types were detected in 50 (67%) premalignant skin lesions, in which Z95963 (accession no. in the EMBL Databank), Z95968, AJ010823, and AJ000151 have been described as partial sequences of unknown HPV types. Furthermore, 2 unknown types, HPVX1 and HPVX2, were found in specimens of actinic keratosis. Sequence analysis showed that HPVX1 is related to HPV-37 (86.1% sequence homology) and that HPVX2 is related to HPV-38 (79.7%). These results indicate that various mucosal and epidermodysplasia verruciformis-related HPV types are associated with the pathogenesis of actinic keratosis and Bowen's disease. In addition, 24 specimens of HPV-positive or HPV-negative premalignant skin lesions were examined immunohistochemically for proliferating cells to determine biological differences between HPV-positive and HPV-negative lesions. Immunohistochemistry for p21(Waf1/Cip1), p53, proliferating cell nuclear antigen (PCNA), Ki-67, and Bcl-2 revealed that there was no significant difference in the cell proliferation activity between HPV-positive and HPV-negative lesions, suggesting that HPV infection alone does not induce cell proliferation in those lesions.

Altered cytokeratin expression in actinic cheilitis

BACKGROUND

Actinic cheilitis (AC) is a widely recognized precancerous lesion of the lip. Varying degrees of epithelial dysplasia may be present. However, no studies have correlated epithelial changes with cytokeratin expression that might reflect the disordered maturation that is probably occurring.

METHODS

Thirty-four cases diagnosed as AC were classified according to dysplasia degree, and submitted to immunohistochemical staining for the detection of cytokeratins (CKs) 7, 8, 13, 14, 16 and 19. Normal mucosa adjacent to the lesions was also evaluated.

RESULTS

The results obtained showed that CK10 immunostained only superficial keratinized epithelial layers in 11 cases, and also intermediate spinous layers in 18 cases. Cytokeratin 14 was expressed in all epithelial layers of 31 cases, in two cases its expression was in the basal and intermediate layers, and one case was negative. Cytokeratin 13 immunostained 26 cases and was negative in eight cases. In these eight cases, CK13 was apparently replaced by CK16. Cytokeratin 16, besides these eight cases, was also expressed in the spinous intermediate layers of a further eight cases. The remaining CKs tested were all negative. No relation between the degree of dysplasia and the CK expression was noted.

CONCLUSIONS

Cytokeratin expression in AC is different from that of normal oral mucosa, and is not related to the degree of dysplasia.

HPLC Profiling of Trp-related Metabolites In Humans

Screening for metabolic abnormalities of Trp has been introduced using SPE pre-treatment, TLC and/or two HPLC procedures. The excretory pattern in urine (occasionally also plasma and CSF levels) has been followed in a group of 390 children showing various symptoms of a metabolic defect and in 195 patients with skin diseases, namely those associated with photosensitivity, such as porphyria, vitiligo, alopecia, psoriasis, erythematodes, and others. Excretory abnormalities of either indican, kynurenine, 3-hydroxyanthranilic acid or indolylacryloylglycine have been occasionally combined with myopathy, seizures, liver and intestinal symptoms. Several indoles and kynurenine derivatives present changes in the alopecia group and the vitiliginous patients.

Pagetoid variant of actinic keratosis with or without squamous cell carcinoma of sun-exposed skin: a lesion simulating extramammary Paget's disease

BACKGROUND

Extramammary Paget's disease usually occurs in anogenital skin. We present five cases of squamous cell carcinoma in situ of sun-exposed skin and non-squamous cell carcinoma in situ actinic keratosis that displayed atypical keratinocytes disposed in intraepithelial cell nests and immunohistochemical staining simulating extramammary Paget's disease.

METHODS AND RESULTS

Two pilot cases--one squamous cell carcinoma in situ and one non-squamous cell carcinoma in situ actinic keratosis with formation of intra-epidermal nests of atypical keratinocytes with a pagetoid spread pattern--were encountered at our institution. Fifty-four consecutive cases of squamous cell carcinoma in situ including bowenoid actinic keratosis and 34 cases of non-squamous cell carcinoma in situ actinic keratosis were reviewed to identify pagetoid spread of atypical cells. Representative sections of all cases with pagetoid spread of atypical keratinocytes were submitted for special stains for mucin, and immunostaining for cytokeratin 7 (CK7), cytokeratin 20 (CK20), cytokeratin CAM 5.2 (CAM 5.2), carcinoembryonic antigen (CEA), vimentin and S100 protein. In the group of squamous cell carcinoma in situ, 10 cases displayed pagetoid spread of atypical keratinocytes with cytoplasm ranging from clear to pale and atypical hyperchromatic nuclei. One review squamous cell carcinoma in situ was multicentric with three separate lesions. The atypical keratinocytes tended to form well to poorly defined cell groups extending from the basal cell layer to the corneal layer. No similar cases were identified in the group of non-squamous cell carcinoma in situ actinic keratosis. Two pilot cases and three of 10 review cases with a total of seven separate lesions displayed a moderate to marked immunohistochemical reactivity for CK7 similar to extramammary Paget's disease. CEA immunoreactivity was also detected in two of these cases. In addition, two of 44 squamous cell carcinomas in situ without pagetoid spread of atypical keratinocytes showed a moderate reactivity for CK7 in very occasional atypical keratinocytes. The remaining seven squamous cell carcinomas in situ with pagetoid spread of atypical keratinocytes were not immunoreactive for CEA and CK7. Immunostaining for CK20, vimentin, S100 protein was negative in all atypical cells in all study cases.

CONCLUSIONS

Actinic keratosis, particularly squamous cell carcinoma in situ of sun-exposed skin, may have histopathological and immunohistochemical features similar to extramammary Paget's disease and probably represents a variant of actinic keratosis. Awareness of the pagetoid variant of actinic keratosis arising in sun-exposed skin is helpful to avoid the over-diagnosis of extramammary Paget's disease.

Accumulation of sapogenin conjugates and histological changes in the liver and kidneys of lambs suffering from alveld, a hepatogenous photosensitization disease of sheep grazing Narthecium ossifragum

Sixteen lambs exhibiting hepatogenous photosensitization (alveld) after grazing pasture containing Narthecium ossifragum and seven nonphotosensitized lambs grazing the same pastures were studied. All the alveld-affected lambs revealed liver damage dominated by single cell necrosis, portal fibroplasia and bile duct proliferation. Crystalloid clefts were demonstrated in the bile ducts of two and in the hepatocytes and Kupffer cells of nine photosensitized lambs. Plasma bilirubin concentration was severely increased in ten of the cases of alveld whereas the activity of aspartate aminotransferase was moderately to severely increased in seven cases. The activity of glutamate dehydrogenase was moderately elevated in one of the photosensitized lambs. The main histopathological findings in the kidneys from the alveld-affected lambs were dilated tubules, often with eosinophilic material in the tubular lumina. Regenerative changes were seen in a large proportion of the renal sections. Elevated plasma concentrations of urea and creatinine, and the renal histopathological changes, suggested that the photosensitized lambs had been through a phase of renal injury. Analysis of the free and conjugated sapogenin content in liver tissue and bile was performed by gas chromatography-mass spectrometry. There were significantly higher concentrations of conjugated episapogenins in both the liver and bile in the alveld-affected lambs than in the nonphotosensitized lambs.

Upregulation of epidermal surface molecule expression in primary and ultraviolet-induced lesions of lupus erythematosus tumidus

BACKGROUND

Lupus erythematosus tumidus (LET), a photosensitive skin disorder with characteristic clinical and histological features, has not been generally accepted as a subset of cutaneous lupus erythematosus (CLE).

OBJECTIVES

To analyse the expression of epidermal surface molecules in skin biopsy specimens from patients with LET and to relate the results to other variants of CLE, such as discoid lupus erythematosus (DLE) and subacute CLE (SCLE).

METHODS

In total, 45 patients with different subtypes of CLE were included in the study, and cryostat sections from primary and ultraviolet (UV) A- and UVB-induced skin lesions were investigated using immunohistochemical methods.

RESULTS

In contrast to healthy controls, skin lesions of LET showed upregulation of intercellular adhesion molecule-1 (ICAM-1) and histocompatibility class II molecules (HLA-DR), with an expression pattern resembling that seen in DLE and SCLE. Furthermore, staining with a monoclonal antibody against 27E10, a distinct marker for cell activation and differentiation, revealed intense focal or band-like labelling of all epidermal layers independent of the type of lesion.

CONCLUSIONS

Expression of epidermal surface molecules such as ICAM-1, HLA-DR and 27E10 is equally upregulated in primary and UV-induced lesions of patients with LET, DLE and SCLE. These results support our recent clinical findings that LET represents a distinct subset of CLE with a similar immunopathomechanism rather than a different disease.

Modulation of biologic endpoints by topical difluoromethylornithine (DFMO), in subjects at high-risk for nonmelanoma skin cancer

More than one million new skin cancers are diagnosed yearly in the United States creating the need for effective primary and chemopreventive strategies to reduce the incidence, morbidity, and mortality associated with skin cancer. Skin chemoprevention trials often focus on subjects at high risk of nonmelanoma skin cancers and include biological endpoints like number of actinic keratoses (AK) and measures of cell proliferation, apoptosis, and p53 expression and/or mutation. Difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, suppresses increased polyamine synthesis and inhibits tumors in models of skin carcinogenesis. Thus, DFMO is a good candidate chemopreventive agent in humans at increased risk of NMSC. We reported previously results of a randomized, placebo-controlled trial of topical DFMO in 48 participants with AK. In this study there was a significant reduction in the number of AK (23.5%; P = 0.001) and the polyamine, spermidine (26%, P = 0.04; Alberts, D. S. et al. Cancer Epidemiol. Biomark. Prev., 9: 1281-2186, 2000). In skin biopsies from the same study, we demonstrate that topical DFMO significantly reduces the percentage of p53-positive cells (22%; P = 0.04); however, there were no significant changes in proliferating cell nuclear antigen or apoptotic indices, or in the frequency of p53 mutations (25% at baseline, 21% after placebo, and 26% after DFMO). We conclude that inhibition of the premalignant AK lesions as well as a reduction in the expression of p53 and in spermidine concentrations may serve as surrogate endpoint biomarkers of DFMO and possibly other topically administered skin cancer chemopreventive agents.

Diseases associated with photosensitivity

Photosensitive disorders may be classified as those entirely caused by solar exposure and the photoaggravated disorders. Those in the former category include polymorphic light eruption, juvenile spring eruption, actinic prurigo, hydroa vacciniforme, solar urticaria, also chronic actinic dermatitis. Genodermatoses whose expression mainly depends on UV or light exposure include the DNA repair deficient disorders, some disorders of cornification, the Smith-Lemli-Opitz syndrome and porphyria. Examples of photoaggravated diseases include lupus erythematosus, erythema multiforme, atopic eczema, psoriasis, viral exanthemata, pemphigus, dermatitis herpetiformis and rosacea. Drugs and chemicals may interact with UV to induce photosensitivity. In many of these diseases the action spectrum is known or may be determined by phototesting. Recognition of the reaction patterns associated with the photodermatoses greatly assists clinical classification of the photodermatoses.

Nuclear transport of photosensitizers during photosensitization and oxidative stress

The nuclear transport pathways of the photosensitizers meso-tetra(4-sulfonatophenyl)porphyrin (TPPS4) and meso-tetra(4-N-methylpyridyl)porphyrin (TMPyP) during photosensitization and oxidative stress were characterized in CT-26 murine colon carcinoma cells using fluorescence microscopy and multi-pixel spectral imaging. Prior to irradiation, TPPS4 and TMPyP localized mainly in the lysosomes, while irradiation or H2O2 treatment induced a relocalization into the nucleus and nucleoli. Flow cytometry analysis of isolated nuclei from the treated cells showed an increase in nuclear fluorescence accompanying the relocalization. Isolation and separation of the nuclear proteins according to molecular weight was performed using a sephadex G-100 column. The protein fractions exhibiting high fluorescence were separated by high performance liquid chromatography. Five major classes of proteins with a retention time of 1, 7, 11, 12 and 15 min were obtained. Each photosensitizer was associated with a distinct class of proteins. While TPPS4 fluorescence was detected in the protein fraction with a retention time of 11 min, TMPyP fluorescence was associated with a protein fraction having a retention time of 7 min. We conclude that although oxidative stress triggers entry into the nucleus of both TPPS4 and TMPyP, each sensitizer uses a distinct transport mechanism based on its chemical properties.

Photomedicine: lessons from the Smith-Lemli-Opitz syndrome

The Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder caused by a discrete block in the cholesterol biosynthetic pathway. Recognition of the metabolic basis of this condition has bought into focus knowledge from fields as diverse as clinical genetics, sterol biochemistry, foetal nutrition, and experimental teratology, resulting in a rush of new insights in these fields. Unfortunately, late recognition of photosensitivity as part of this syndrome has largely excluded photodermatologists and photobiologists from the recent frenzy of research in this disorder. However, clinical features of this new inherited photosensitivity syndrome have now been established, and monochromator light testing has confirmed it to be a UVA-mediated condition. Current knowledge concerning photosensitivity in SLOS is reviewed and future research into the pathogenesis of this disorder is discussed.

Ultraviolet light downregulates CD95 ligand and TRAIL receptor expression facilitating actinic keratosis and squamous cell carcinoma formation

Long-term ultraviolet light exposure of human skin epidermis in Caucasians is associated with an increased risk for the development of melanoma and nonmelanoma skin cancers. Ultraviolet radiation not only induces DNA damage in epidermal cells, it also interferes with skin homeostasis, which is maintained by a unique distribution pattern of apoptosis-inducing and apoptosis-preventing molecules. We demonstrate that, beside CD95 ligand, TRAIL and TRAIL receptors also function as important sensors in the human epidermis preserving skin integrity and preventing cell transformation. Ultraviolet irradiation extensively changes the expression pattern of some of these molecules, diminishing their sensor function. In particular, CD95 ligand and to a somewhat lesser extent TRAIL receptors are downregulated upon ultraviolet light exposure. CD95 ligand downregulation is not due to protein degradation as in situ hybridization experiments strongly support a transcriptional regulation. The downregulation of these molecules with sensor function increases the risk that aberrant cells are less efficiently eliminated. This concept is supported by the fact that the expression of these molecules is also low or absent in actinic keratosis, a precancerous state that has developed as the consequence of long-term ultraviolet exposure. Progression to invasive neoplasms is then accompanied by an upregulation of CD95 ligand and a downregulation of CD95 and of the TRAIL receptors. The high expression of CD95 ligand, TRAIL, and FLIP in squamous cell carcinoma may then contribute to the immune escape of the tumor, whereas the lack of expression of CD95 and TRAIL receptors prevents autolysis of the tumor.

Immunohistochemical detection of lipid peroxidation products, protein-bound acrolein and 4-hydroxynonenal protein adducts, in actinic elastosis of photodamaged skin

Acrolein and 4-hydroxy-2-nonenal (HNE) are both byproducts of a lipid peroxidation reaction. Actinic elastosis in photodamaged skin of aged individuals is characterized by the accumulation of fragmented elastic fibers in the sun-exposed areas. To study whether a lipid peroxidation reaction is involved in the accumulation of altered elastic fibers in actinic elastosis, skin specimens obtained from sun-damaged areas were immunohistochemically examined using the antibodies against acrolein and HNE. Both antibodies were found to react with the accumulations of elastic material. Double immunofluorescence labeling demonstrated that acrolein/elastin and HNE/elastin were colocalized in the actinic elastosis. Western blot analysis showed that the polypeptide with a molecular weight of 62 kDa reacted with anti-acrolein, anti-HNE and anti-elastin antibodies. The results suggest that acrolein and HNE may be associated with actinic elastosis.

Alteration of the endocytotic pathway by photosensitization with fluoroquinolones

The endocytotic pathway is profoundly altered by the UVA-induced photosensitization of HS 68 fibroblasts by the fluoroquinolone (FQ) antibiotics lomefloxacin, BAYy 3118, norfloxacin and ciprofloxacin, which preferentially localize in lysosomes. The endocytosis of low-density lipoproteins (LDL) loaded with two carbocyanine dyes compatible for effective Forster-type resonance energy transfer (FRET), namely 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) as the donor and 1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as the acceptor, has been used as a model system. Binding of LDL to their cell surface receptors is impaired by irradiation with 10 J cm(-2) of UVA and/or treatment with 250 microM BAYy 3118 during 2 h. Perturbation of the plasma membrane by the FQ is revealed by the change in the rate of exchange of DiO from the LDL to the cell membrane as compared to untreated cells. The lysosomal degradation of LDL, demonstrated by the disappearance of FRET between DiO and DiI, is partly inhibited by the FQ. The actin filament network, involved in the fusion of mature endosomes with lysosomes, is readily destroyed upon photosensitization with the four FQ. However, actin depolymerization can be avoided by incubation of the cells with trans-epoxysuccinyl-1-leucylamido-(4-guanidino)butane, an inhibitor of lysosomal cathepsins prior to FQ photosensitization. All these data suggest that several components of the endocytotic pathway are impaired by photosensitization with these FQ.

Functional and morphological studies of photodamaged skin on the hands of middle-aged Japanese golfers

The skin of golfers' hands provides a suitable model to study the effect of chronic sun exposure, because one of their hands is exposed to the outer environment, especially sunlight, while the other one is always protected by a glove during play. Our purpose was to find out the influence of photodamage on the properties of the skin surface of middle-aged Japanese by using non-invasive methods. We measured hydration state, and water barrier function of the stratum corneum (SC) and the color of the skin of the dorsum of the hands. In a separate study, we evaluated the skin surface contour by using replicas taken from the skin in a slightly stretched or relaxed position. We found a significant decrease in hydration of the skin surface of the exposed skin as compared to that of the protected skin, whereas no such difference was found with transepidermal water loss, a parameter for water barrier function of the SC. Luminance of skin color was also reduced in the sun-exposed skin. Replica analysis revealed that large wrinkles developing in a relaxed position were more prominent on the exposed than on the protected skin, while fine furrows noted in a slightly stretched position were shallower on the former than the latter. The data obtained indicate that the chronically exposed skin of golfers' hands shows morphological and functional changes resulting from long time exposure to the outer environment especially sunlight. Furthermore, bioengineering non-invasive methods are found to be useful to detect early photodamage of the skin in a more quantitative fashion which is rather difficult to demonstrate clinically.

Polymorphous light eruption. A case report and consideration of the hardening mechanism

BACKGROUND

Polymorphous light eruption (PLE) is a common form of photodermatosis. The pathogenesis of the disease and the mechanism of the hardening phenomenon, however, have not been clarified.

OBSERVATION

We report a 62-year-old Japanese woman with PLE. Provocation and hardening induction testing revealed that hardening was induced at the sites irradiated by a sufficient dose of UV for reproduction of the lesion. Topical steroid could prevent a positive reaction but not the hardening induction. The expression of adhesion molecules and CD1a was decreased at the hardening site.

CONCLUSION

From these results, the hardening phenomenon in our case might be due to immunosuppression by UV exposure supported by the down-regulation of cell adhesion molecule expression and partially due to the depletion of endogenous antigens which cause a delayed-type hypersensitivity reaction.

Possible involvement of enhanced prostaglandin E2 production in the photosensitivity in xeroderma pigmentosum group A model mice

Xeroderma pigmentosum group A (XPA) gene-deficient mice cannot repair UV-induced DNA damage and easily develop skin cancers by UV irradiation. Therefore, XPA-deficient mice are a useful model of human XP and represent a promising tool for photobiologic studies of the disorder. Exposure to ultraviolet (UV) B (280-320 nm) radiation greatly enhanced inflammation and immunosuppression in these mice. To investigate the molecular mechanisms of enhanced UV inflammation and immunosuppression, we determined the amount of prostaglandin (PG) E2, an inflammatory mediator and immunomodulator, and analysed the expression of cyclooxygenase (COX) mRNA in the ear skin of XPA-deficient mice after UV irradiation. In XPA-deficient mice, the amount of PGE2 significantly increased at 48 and 72 h after UVB irradiation to the level that was 8- and 16-fold higher than those in wild-type mice, respectively. The expression level of COX-2 mRNA increased in a time-dependent manner, although COX-1 mRNA was constantly expressed. Treatment with indomethacin, a potent inhibitor of PG biosynthesis, inhibited UV-induced ear swelling, abrogated local immunosuppression, and decreased the amount of PGE2 in the ear skin of XPA-deficient mice. These results indicate that the excess DNA photoproducts remaining in XPA-deficient cells after UV radiation may induce COX-2 expression. The induced production of PGE2 may be involved in the enhanced inflammation and immunosuppression caused by UV radiation in XPA-deficient mice and XP patients.