The minimal erythema dose of broadband ultraviolet B in Taiwanese

Circadian Oscillations of Minimal Erythema Dose (MED) are Also Influenced by Diet in Patients with Psoriasis: A Chronomedical Study

INTRODUCTION

Minimal erythema dose (MED) remains a parameter of paramount importance to orient narrow-band (NB)-UVB phototherapy in psoriatic (PsO) patients. Recently, circadian rhythm and diet were recognized as potential MED modulators, but their mutual interaction remains understudied. Thus, we aimed to evaluate the potential diet modulation of MED circadian oscillations.

METHODS

In the first phase, a cohort study was performed comparing potential MED oscillations (morning, afternoon, and evening) among omnivorous psoriatic patients before and after a phototherapy cycle and omnivorous healthy controls. The two groups were age-, gender-, skin-type-, MED-, and diet-matched. Then, in the second phase, another cohort study was carried out comparing MED oscillations 24 h after the last phototherapeutic session only in psoriatic patients cleared with NB-UVB and undergoing different diets (vegan, vegetarian, paleo , ketogenic, intermittent circadian fasting, and omnivore). Patients with different diets were age-, gender-, and skin-type matched.

RESULTS

In the first phase, we enrolled only omnivores, specifically 54 PsO patients and 54 healthy individuals. Their MED before and after NB-UVB therapy changed significantly among the three different time-points (morning, afternoon, and evening) (p < 0.001). The time effect was statistically significant in both groups before and after phototherapy. In the second phase, we enrolled 144 PsO patients (vegan, vegetarian, paleo, ketogenic, intermittent circadian fasting, and omnivore). MED circadian oscillations preserved a significant difference also after clearance and were influenced by diet type and time of day (p < 0.001). In particular, vegans displayed the lowest MED values, whilst Ramadan fasting showed the highest values in morning, afternoon, and evening.

CONCLUSIONS

Diet, like other ongoing therapies, should be reported in the medical records of patients with psoriasis undergoing NB-UVB and patients with lower MEDs should be preferentially treated in the morning when the MED is higher.

Ultraviolet B phototherapy does not increase the risk of skin cancer among patients with atopic dermatitis: A population-based retrospective cohort study

BACKGROUND

UV-B phototherapy is a common treatment modality for patients with atopic dermatitis (AD), but its long-term safety in terms of cutaneous carcinogenic risk has not been studied.

OBJECTIVE

To investigate the risk of skin cancer among patients with AD receiving UV-B phototherapy.

METHODS

We conducted a nationwide population-based cohort study from 2001 to 2018 to estimate the risk of UV-B phototherapy for skin cancer, nonmelanoma skin cancer, and cutaneous melanoma in patients with AD.

RESULTS

Among 6205 patients with AD, the risks of skin cancer (adjusted hazard ratio [HR], 0.91; 95% CI, 0.35-2.35), nonmelanoma skin cancer (adjusted HR, 0.80; 95% CI, 0.29-2.26), and cutaneous melanoma (adjusted HR, 0.80; 95% CI, 0.08-7.64) did not increase among patients with AD treated with UV-B phototherapy, compared with those who did not receive UV-B phototherapy. Additionally, the number of UV-B phototherapy sessions was not associated with an increased risk of skin cancer (adjusted HR, 0.99; 95% CI, 0.96-1.02), nonmelanoma skin cancer (adjusted HR, 0.99; 95% CI, 0.96-1.03), or cutaneous melanoma (adjusted HR, 0.94; 95% CI, 0.77-1.15).

LIMITATIONS

Retrospective study.

CONCLUSION

Neither UV-B phototherapy nor the number of UV-B phototherapy sessions was associated with an increased risk of skin cancers among patients with AD.

Activation of the JNKs/ATM-p53 axis is indispensable for the cytoprotection of dermal fibroblasts exposed to UVB radiation

Although UVB radiation is mainly absorbed by the epidermis, ~5-10% of its photons reach and affect the upper part of the dermis. Physiologically relevant UVB doses, able to provoke erythema, induce apoptosis in human dermal fibroblasts in vitro, as well as in the dermis of SKH-1 mice. Given the sparse and even contradictory existing information on the effect of UVB radiation on dermal fibroblasts' viability, aim of this work was to unravel the crucial signaling pathways regulating the survival of UVB-treated human dermal fibroblasts. We found that UVB radiation immediately stimulates the phosphorylation of MAPK family members, as well as Akt, and is genotoxic leading to the delayed ATM-p53 axis activation. Akt phosphorylation after UVB radiation is EGFR-mediated and EGFR inhibition leads to a further decrease of viability, while the Akt activator SC79 rescues fibroblasts to an extent by a mechanism involving Nrf2 activation. The known Nrf2 activator sulforaphane also exerts a partial protective effect, although by acting in a distinct mechanism from SC79. On the other hand, inhibition of JNKs or of the ATM-p53 axis leads to a complete loss of viability after UVB irradiation. Interestingly, JNKs activation is necessary for p53 phosphorylation, while the ATM-p53 pathway is required for the long-term activation of JNKs and Akt, reassuring the protection from UVB. Although UVB radiation results in intense and prolonged increase of intracellular ROS levels, classical anti-oxidants, such as Trolox, are unable to affect Akt, JNKs, or p53 phosphorylation and to reverse the loss of fibroblasts' viability. Collectively, here we provide evidence that the main viability-regulating UVB-triggered biochemical pathways act synergistically towards the protection of human dermal fibroblasts, with EGFR/Akt and Nrf2 serving as auxiliary anti-apoptotic machineries, while JNKs/ATM-p53 activation and interplay being overriding and indispensable for the perpetuation of cellular defense and the maintenance of cell viability.

Minimal Erythema Dose: Correlation with Fitzpatrick Skin Type and Concordance Between Methods of Erythema Assessment in a Patient Sample in Colombia

BACKGROUND AND OBJECTIVE

The minimal erythema dose (MED), an essential measurement in studies of skin photosensitivity, requires establishing MED values for specific populations, given genetic variation. Different ways to assess erythema are also relevant. We aimed to determine MED values in a sample of Colombian patients and correlations between MED and Fitzpatrick skin type. We also studied concordance correlation between MEDs and two alternative ways to assess erythema.

PATIENTS AND METHODS

Cross-sectional study of 113 individuals in Bogotá, Colombia. We used a solar simulator to measure UV-A radiation and combined UV-A and UV-B (UVA+UVB) radiation, o se podría suprimir este término porque UVA y UVB son términos conocidos for MED calculation. Narrowband UV-B (NBUVB) radiation was measured in a phototherapy cabin. Erythema was assessed visually and with a Mexameter MX 18 device.

RESULTS

The median MEDs of UVA+UVB radiation were 22mJ/cm² for Fitzpatrick skin typesI andII, and 33 and 43mJ/cm², respectively, for typesIII andIV. The MEDs of UV-A radiation were 22, 42, 86, and 100J/cm² for typesI, II, III, andIV, respectively. The MEDs of NBUVB light were 390, 550, 770, and 885mJ/cm² for the 4 skin types. The correlation between MEDs and skin types ranged from 0.5 to 0.69. Lin's concordance correlation coefficients between visual and Mexameter assessments of erythema were greater than 0.8 in all cases.

CONCLUSION

This study allowed us to understand MED values for UV-A, UVA+UVB, and NBUVB according to different skin types in the Colombian population. Concordance correlation coefficients between the different methods of erythema assessment were very good. Correlations between MEDs and skin types were moderate to good.

Identification of factors associated with minimal erythema dose variations in a large-scale population study of 22 146 subjects

Background

Minimal erythema dose (MED) has substantial inter‐ and intraindividual variations, reflecting the influence of very diverse factors. However, related studies showed little consistency probably because of their limited sample size.

Objective

To identify the factors associated with MED variations in a large‐scale population study.

Methods

The MED test was performed by following the international standard procedure on 22 146 subjects. The results were analysed in adjusted multivariable linear and logistic regression models.

Results

This large‐scale study revealed that lower MED was consistently associated with lighter skin [β‐coefficient = −0.33, 95% confidence interval (CI) −0.36 to 0.30, P = 6.41 × 10⁻⁸⁴]. Females had significantly higher MED than male (β = 0.91, 0.32–1.50, P = 2.93 × 10⁻³). Stratified analyses showed that MED was not associated with age [female: odds ratio (OR) = 0.99, 0.98–1.01; male: OR = 0.99, 0.97–1.00]. MED was lower in summer than in other seasons (spring: OR = 1.08, 1.06–1.11; autumn: OR = 1.11, 1.08–1.13; winter: OR = 1.20, 1.18–1.22). Furthermore, MED was associated with air temperature (β = −0.36, −0.49 to 0.23, P = 4.81 × 10⁻⁸) and air pressure (β = −0.64, −0.82 to 0.46, P = 8.01 × 10⁻¹²) in summer only while not in other seasons.

Conclusions

This study provides unprecedented evidence that MED is associated with skin colour, sex, season and meteorological factors, but not with age.

Human mesenchymal stem cells are resistant to UV-B irradiation

Albeit being an effective therapy for various cutaneous conditions, UV-B irradiation can cause severe skin damage. While multipotent mesenchymal stem cells (MSCs) may aid the regeneration of UV-B-induced skin injuries, the influence of UV-B irradiation on MSCs remains widely unknown. Here, we show that human MSCs are relatively resistant to UV-B irradiation compared to dermal fibroblasts. MSCs exhibited higher clonogenic survival, proliferative activity and viability than dermal fibroblasts after exposure to UV-B irradiation. Cellular adhesion, morphology and expression of characteristic surface marker patterns remained largely unaffected in UV-irradiated MSCs. The differentiation ability along the adipogenic, osteogenic and chondrogenic lineages was preserved after UV-B treatment. However, UV-B radiation resulted in a reduced ability of MSCs and dermal fibroblasts to migrate. MSCs exhibited low apoptosis rates after UV-B irradiation and repaired UV-B-induced cyclobutane pyrimidine dimers more efficiently than dermal fibroblasts. UV-B irradiation led to prolonged p53 protein stability and increased p21 protein expression resulting in a prolonged G2 arrest and senescence induction in MSCs. The observed resistance may contribute to the ability of these multipotent cells to aid the regeneration of UV-B-induced skin injuries.

The effect of pre-phototest sun exposure on minimal erythema dose and minimal melanogenic dose among skin phototypes III, IV and V

BACKGROUND

Ethnicity, skin phototype and colour influenced minimal erythema dose (MED). Sun exposure has been postulated to increase MED. We determined immediate pigment darkening dose to UVA (IPDDA), MED and minimal melanogenic dose (MMD) for UVB and UVA, and investigated factors affecting these doses.

METHODS

Skin phototype was determined using Fitzpatrick phototype quiz, DSMII ColorMeter measured skin colours, sun exposure quantified using an index (SEI) and phototest performed with MEDlight-Multitester.

RESULTS

A total of 167 healthy volunteers participated. There were 110 (66%) females and 56 (34%) males; 124 (74.7%) were Malay, 27 (16.3%) Chinese and 14 (8.4%) Indians. One hundred and nine (65.7%) skin phototype IV, 30 (18.1%) phototype III and 27 (16.3%) phototype V. IPDDA ranges from 6 ± 1.5-5.7 ± 1.4 J/cm² . MED-UVB were 96.9 ± 17.6, 124 ± 29.3 and 118.6 ± 27.4 mJ/cm² for phototype III, IV and V, respectively. All MED-UVA were outside the tested dose range of 3.6-11 J/cm² . MMD-UVB were 106 ± 18.2, 134 ± 25.6 and 136 ± 31.1 mJ/cm² while MMD-UVA were 4.1 ± 4.1, 4.9 ± 3.8 and 5.7 ± 3.7 J/cm² respectively for phototypes III, IV and V. MED-UVB, MMD-UVB and MMD-UVA did not depend on skin phototype. Facultative skin whiteness (L*), erythema (E) and melanin content (M) correlated significantly with MED-UVB while constitutive skin colours were significant for L*, yellowness (b*), E and M. Sun exposure did not significantly correlate with MED-UVB and MMDs, however, an inverse relationship with MED-UVB was demonstrated.

CONCLUSION

Minimal erythema doses in our cohort were slightly different from other regional countries. Constitutive and facultative skin whiteness, erythema and melanin content correlated with MED. There was no association between skin phototype and sun exposure with MED or MMD.

Increased risk of chronic kidney disease in patients with rosacea: A nationwide population-based matched cohort study

Background

Rosacea is a chronic inflammatory skin disorder. Inflammation and oxidative stress are involved in the etiopathogenesis of rosacea and chronic kidney disease (CKD). This study aimed to investigate the association between rosacea and CKD.

Methods

This population-based cohort study identified 277 patients with rosacea in the Taiwan National Health Insurance Research Database during 2001–2005. These patients were matched for age, sex, and comorbidities with 2216 patients without rosacea. All subjects were individually followed-up for 8–12 years to identify those who subsequently developed CKD

Results

The incidence rates of CKD per 1000 person-years were 16.02 in patients with rosacea and 10.63 in the non-rosacea reference population. After adjusting for other covariates and considering the competing risk of mortality, patients with rosacea remained at increased risk of CKD (adjusted sub-distribution hazard ratio (aSD-HR) 2.00; 95% confidence interval (CI) 1.05–3.82). The aSD-HRs (95% CI) for CKD were 1.82 (0.83–4.00) and 2.53 (1.11–5.75) for patients with mild and moderate-to-severe rosacea, respectively.

Conclusions

Rosacea is an independent risk factor for CKD. High rosacea severity and old age further increased CKD risk in patients with rosacea. Careful monitoring for CKD development should be included as part of integrated care for patients with rosacea.

UV "Indices"-What Do They Indicate?

Ultra-Violet (UV) radiation covers the spectrum of wavelengths from 100 to 400 nm. The potency and biological activity for a variety of endpoints differ by wavelength. For monitoring and communication purposes, different UV action spectra have been developed. These spectra use different weighting functions. The action spectrum for erythemal dose is the most widely used one. This erythemal dose per time or dose-rate has been further simplified into a “UV index”. Following this example, in our review we use the term “index” or (plural) “indices” in a more general description for all simplified single-value measures for any biologically effective UV dose, e.g., for human non-melanoma skin cancer and for previtamin D production rate. Ongoing discussion about the existence of an increased melanoma risk due to UV-A exposure underscores the uncertainties inherent in current weighting functions. Thus, we performed an online literature search to review the data basis for these indices, to understand their relevance for an individual, and to assess the applicability of the indices for a range of exposure scenarios. Even for natural (solar) UV, the spectral composition varies spatially and temporally. Artificial UV sources and personal protection introduce further variation to the spectral composition. Many biological effects are proposed for UV radiation. Only few endpoints have been studied sufficiently to estimate a reliable index. Weighting functions for chronic effects and most importantly for cancer endpoints have been developed in animal models, and often for proxy endpoints only. Epidemiological studies on biological effects of UV radiation should not only depend on single-value weighted UV dose estimates (indexes) but should strive for a more detailed description of the individual exposure. A better understanding of the adverse and beneficial effects of UV radiation by wavelength would also improve medical counseling and health communication regarding individual health-supportive behavior.

UV responses in Native Hawaiians and Pacific Islanders, and Asians residing in Hawai'i and in Maryland

BACKGROUND

UV exposure causes a wide range of skin damage including cutaneous melanoma. The mechanisms of cellular and molecular damage, as well as those of erythemal and pigmentation responses to UV exposure, have largely been studied in the White population.

METHODS

This study systematically investigates responses to UV exposure in the Native Hawaiian and Pacific Islander (NHPI) and Asian populations living in Hawai'i (A/HI) as well as in Asians living in Maryland (A/MD).

RESULTS

Our analyses indicate that the NHPI population is less sensitive to UV exposure than the A/HI population. Comparisons between the two Asian groups suggest that, despite slightly but not statistically different baseline constitutive pigmentation (pre-UV exposure), the A/HI and A/MD had similar UV sensitivity, measured as minimal erythemal dose (MED). However, the A/MD population had higher levels of oxyhemoglobin at doses of 2.0, 2.8 and 4.0 MED. Unexpectedly, the A/MD subjects retained higher levels of pigmentation 2 weeks post-UV exposure.

CONCLUSION

This study provides insight into UV responses of the inhabitants of Hawai'i and shows that such responses are statistically significant for relatively small samples of NHPI and for A/HI and A/MD.

Clinicopathologic study of solar dermatitis, a pinpoint papular variant of polymorphous light eruption in Taiwan, and review of the literature

BACKGROUND/PURPOSE

A mild, micropapular eruption previously coined as "solar dermatitis" on the extensor of the forearm is a common form of photodermatitis in Taiwan. This study aimed to investigate the clinicopathologic findings of "solar dermatitis", the micropapular type of photodermatitis.

METHODS

We characterized the features of this photodermatitis by retrospectively reviewing and analyzing all such cases in a medical center in Southern Taiwan diagnosed during October 1988 to November 2010.

RESULTS

A total of 34 Taiwanese patients, all with Fitzpatrick skin type III-IV, were included (M:F = 1:1; mean age = 33.5 years; range = 9-62 years). Patients typically presented numerous, monomorphous, pinhead-sized micropapules on the extensor of the forearm after a recent, more intense sun exposure. The rash was often mildly pruritic and recurred in the summer, but usually resolved in a few days after sun protection and topical corticosteroid treatment. Reduced minimal erythema dose to UVB was noted in 2 of the 5 patients tested. Histopathologic examination (n = 10) revealed a mild spongiotic dermatitis.

CONCLUSION

The clinicopathologic findings of the "solar dermatitis" closely resembled those of the pinpoint papular variant of polymorphous light eruption (PP-PMLE) affecting African Americans and Asians in Singapore. PP-PMLE, micropapular light eruption in Japanese, summertime actinic lichenoid eruption in Indians and the present photodermatitis might represent a common, micropapular variant of PMLE affecting darker skin populations.

Prostaglandin-E2 is produced by adult human epidermal melanocytes in response to UVB in a melanogenesis-independent manner

Excessive ultraviolet radiation (UVR) exposure induces erythema, mediated in part by prostaglandin-E₂ (PGE₂). While keratinocytes are a major PGE₂ source, epidermal melanocytes (EM) also express PGE₂-production machinery. It is unclear whether EM-produced PGE₂ contributes to UVR-induced skin inflammation, and whether this is correlated with melanogenesis. Epidermal melanocytes were cultured from skin phototype-1 and -4 donors, followed by assessment of PGE₂ production and melanogenesis. Epidermal melanocytes expressed cytoplasmic phospholipase-A₂, cyclooxygenase-1, cytoplasmic prostaglandin-E synthase and microsomal prostaglandin-E synthase-1, -2. Epidermal melanocytes produced PGE₂ under basal conditions, which increased further after arachidonic acid stimulation. Epidermal melanocytes expressed cyclooxygenase-2 (COX-2) mRNA and a selective COX-2 inhibitor (NS-398) reduced PGE₂ production. Ultraviolet B-induced PGE₂ production was positively correlated with skin phototype-1, despite variability between individual EM donors. By contrast, there was no correlation between PGE₂ production by EM and their melanogenic status. Thus, EM may contribute to UVR-induced erythema, with role of donor skin phototype more important than their melanogenic status.