Three randomised phase I/IIa trials of 5% cis-urocanic acid emulsion cream in healthy adult subjects and in patients with atopic dermatitis.

New treatment modalities are needed in atopic dermatitis. We evaluated the pharmacokinetics, safety, tolerability, and efficacy of topical cis-urocanic acid (cis-UCA) cream in randomised vehicle-controlled double-blinded clinical trials. The subjects received 5% cis-UCA emulsion cream and control vehicle on volar forearms after right-left randomisation. Study 1: 16 healthy subjects received one dose on the skin and, a week later, on DMSO-irritated skin. Study 2: 16 healthy subjects received 2 daily doses for 10 days. Study 3: 13 patients with mild to moderate disease were treated on selected skin lesions twice daily for 28 days. Study treatments were well tolerated. cis-UCA remained close to endogenous levels in plasma and urine. cis-UCA reduced transepidermal water loss (TEWL) both in healthy subjects and in the patients. Eczema area severity index and physician's global assessment improved from baseline with both treatments. cis-UCA cream improved skin barrier function and suppressed inflammation in the human skin.

UV-induced tolerance to a contact allergen is impaired in polymorphic light eruption.

Polymorphic light eruption (PLE) is a common skin disorder provoked by exposure to UVR. Its clinical symptoms resemble those of a contact allergic reaction. PLE is generally considered a T-cell-mediated autoimmune reaction toward a yet unidentified antigen formed in UVR-exposed skin. Predisposition to such an immune reaction may result from aberrant epitope formation, increased immune reactivity to a universal epitope, or diminished propensity to UVR-induced immunosuppression or to the induction of tolerance. In a study comprising a total of 24 PLE patients and 24 healthy sex- and age-matched controls, we found that both groups demonstrated similar immunosuppression of contact sensitization to diphenylcyclopropenone by earlier exposure to solar-simulating UVR. However, only 1 out of 13 PLE patients (8%) versus 6 out of 11 controls (55%) that had been immunosuppressed by UVR exhibited a state of immunotolerance toward the same allergen after 10-24 months (P=0.023). We conclude that the impaired propensity to UVR-induced allergen-specific immunotolerance may promote recurrent PLE.

Clinical associations of the risk alleles of HLA-Cw6 and CCHCR1*WWCC in psoriasis.

The PSORS1 locus is the consistently replicated genetic risk factor for psoriasis. Clinical associations with the main marker allele of PSORS1, HLA-Cw6, have been addressed in a number of studies, but clinical associations have not been used as a way to distinguish the effects of the neighbouring candidate genes in PSORS1. Our results show that HLA-Cw6 and CCHCR1 risk allele associations with clinical features of psoriasis are predictably highly similar in a Finnish nationwide cohort of 379 psoriasis patients. The clinical profiling of a small group of patients (n=34) who were HLA-Cw6- but CCHCR1*WWCC positive suggested that no great differences existed between them and HCR-Cw6- patients. HCR+ genotype (as well as Cw6+ genotype) correlated for the first time positively with female sex and, in contrast with previous studies, negatively with disease severity. Presence of psoriatic arthritis was more pronounced in HCR- psoriasis (as well as in Cw6- psoriasis). Clinical profiling may be a useful approach to distinguishing genetic effects of candidate genes even within a locus in sufficiently large cohorts.

Population exposure to ultraviolet radiation in Finland 1920-1995: Exposure trends and a time-series analysis of exposure and cutaneous melanoma incidence.

Ultraviolet radiation (UVR) is the principal cause of cutaneous malignant melanoma (CMM). However, the relation between CMM and UVR exposure is not clear. We present the trends of population exposure to UVR and conduct a time-series analysis of the relation between UVR exposure and incidence of CMM. Data on CMM incidence were obtained from the Finnish Cancer Registry. Clothing coverage of the body was scored from archival photographs and the proportion of uncovered skin was used as a measure of solar exposure. Information on the number of sunny resort holidays, duration of annual holidays, and sunscreen sales were obtained from various sources. Exposed skin area doubled from 1920 to 1985. The average duration of annual holidays increased 30-fold. The number of sunny resort holidays and the sales of sunscreens increased rapidly from 1980. CMM was most strongly associated with solar exposure of 5-19 years earlier. There is a considerable decrease in clothing coverage during the 20th century. UVR exposure preceding CMM occurrence 4 years or less does not appear relevant, whereas the period 5-19 years prior to CMM occurrence might be the most relevant period. However, findings of ecological studies may not be applicable at the individual level.

Adaptation of the human skin by chronic solar-simulating UV irradiation prevents ultraviolet-B irradiation-induced rise in serum C-reactive protein levels.

Exposure of the skin to UV radiation induces local inflammation. We hypothesized that inflammation induced by erythemal UV-B irradiation could elevate levels of serum C-reactive protein (CRP) and that suberythemal repeating doses of solar-simulating UV radiation (SSR) would produce photoadaptation to such inflammation. Separation-free high-sensitivity assays of CRP show an increase by 42% (P = 0.046) in CRP concentrations in healthy human subjects 24 h after a 3 minimal erythemal dose (MED) dose of UV-B delivered onto a 100 cm2 skin area. Preceding daily suberythemal doses of whole-body SSR for 10 or 30 consecutive days completely prevented the CRP increase. UV-B-induced skin erythema was partially attenuated by 30 preceding days of SSR only (P = 0.00066). After 10 daily SSR doses, the mean baseline CRP concentrations (0.24 +/- 0.21 mg/L) declined by 35% (P = 0.018). Using high-sensitivity analysis of serum CRP as the endpoint marker for cutaneous inflammation, we show that acute exposure of even a relatively small skin area to erythemal UV-B induces skin inflammation detectable also at the systemic level and that photoadaptation by preceding repeating suberythemal doses of SSR reduces signs of inflammation. Our data complement the view given by previous studies in that local photoadaptation also has systemic manifestations.

Demonstration of UV-dimers in human skin DNA in situ 3 weeks after exposure.

Data on DNA repair rates of specific types of DNA lesions are very limited in humans in situ. Rate of repair of UV-induced DNA damage was followed in the skin of 17 volunteers up to 3 weeks of UV exposure, using a (32)P-postlabelling technique for the determination of specific photoproducts. The subjects of skin phototypes I and IV were exposed to 40 mJ/cm(2) of solar simulating radiation on buttock skin, and biopsies were taken at 0 h, 48 h and 3 weeks of exposure for the analysis of two cyclobutane pyrimidine dimers, TT=C and TT=T, and two 6-4 photoproducts, TT-C and TT-T, as trinucleotides. Repair rates were heterogeneous for different photoproducts. T=T dimers were repaired slower than C=T dimers, and 2.3-9.0% of the initial T=T damage remained unrepaired after 3 weeks, and was detectable in 16/17 subjects. The identity of the identified photoproducts was confirmed by a photochemical reversion assay. Damage level correlated with skin types, type I being more sensitive than type IV in an age-matched comparison. This is the first time the persistence of defined human DNA damage is demonstrated up to 3 weeks. Long-lasting DNA damage increases the likelihood of mutations.

In situ repair of cyclobutane pyrimidine dimers in skin and melanocytic nevi of cutaneous melanoma patients.

The development of cutaneous malignant melanoma (CMM) and its precursor lesions, melanocytic nevi, has been linked to sun exposure. Cyclobutane pyrimidine dimers (CPDs) are the majority of DNA lesions induced by sun exposure. In our study, we investigated if CMM patients have impaired ability to repair CPDs in skin as well as in melanocytic nevi. The repair kinetics were followed up to 3 weeks after exposure to 40 mJ/cm(2) of solar simulating radiation. Altogether 12 CMM patients and 10 healthy controls were included in our study. Buttock skin biopsies were taken at 0 hr, 48 hr and 3 weeks after UV exposure, whereas melanocytic nevi and surrounding skin biopsies were taken only at 0 hr and 3 weeks. The CPD levels were measured by a (32)P-postlabeling method. The results showed that the repair rate of CPDs in neither the skin nor the nevi was significantly different between the CMM patients and the control group. For both groups, the repair rate of TT = C was faster than that for TT = T. The important finding is that about 10% of the initial TT = T damage remained unrepaired after 3 weeks, and was detectable in normal epidermis as well as in nevi of all subjects. We also found that the amount of TT = C and TT = T at 0 hr in nevi was significantly lower than that in surrounding skin (Wilcoxon rank sum test, p < 0.05).

Ultraviolet photoproduct levels in melanocytic nevi and surrounding epidermis in human skin in situ.

Melanocytic nevi are localized benign proliferations of melanocytes. The number of nevi has been shown to be the major risk marker for the development of cutaneous melanoma. This study compares the induction of photoproducts in nevi and in surrounding skin after exposure to solar-simulating radiation. Cyclobutane pyrimidine dimers (TT=T and TT=C) and 6-4 photoproducts (TT-T and TT-C) were measured in 20 nevi and 20 surrounding skin samples obtained from 14 subjects, using a 32P-postlabeling method. The amount of all four types of photoproducts in nevi was found to be 3-5-fold lower than that in surrounding skin, and the difference was statistically significant (paired t test, p < 0.01). In nevi, the photoproduct level was significantly associated with the color of nevi (the lowest level in the darkest color of nevi; r = -0.86, p < 0.01 for TT=T; r = -0.68, p < 0.01 for TT=C). Our findings suggest that the magnitude of the DNA damage is not a sole risk marker for the development of cutaneous melanoma.