A variety of skin responses to ultraviolet irradiation in patients with atopic dermatitis

Clinicophotobiological Characterization of Photoaggravated Atopic Dermatitis

Importance

Photoaggravated atopic dermatitis (PAD) is estimated to affect 1.4% to 16% of patients with AD but remains poorly characterized with limited published data.

Objective

To provide detailed clinical and photobiological characterization of PAD.

Design, Setting, and Participants

This case series study used cross-sectional data collected from 120 consecutive patients diagnosed with PAD from January 2015 to October 2019 at a tertiary center referral unit for photobiology.

Main Outcomes and Measures

Routinely collected standardized clinical and photobiological data were analyzed using descriptive statistics, and regression analysis explored associations between demographic and clinical data.

Results

Of 869 patients who underwent photoinvestigation, 120 (14%) were diagnosed with PAD (69 female [58%]; median age, 45 [IQR, 31-61] years; range, 5-83 years; skin phototypes [SPTs] I-VI). Of these patients, 104 (87%) were adults. All patients had a history of AD, and most (62 of 104 [60%]) presented with sunlight-provoked or photodistributed eczema; median age at photosensitivity onset was 37 years (range, 1-72 years). Past-year Dermatology Life Quality Index score was greater than 10 for 80 of 103 adults (78%), and 82 of 119 (69%) had vitamin D (25-hydroxyvitamin D) level insufficiency or deficiency (<20 ng/mL; to convert ng/mL to nmol/L, multiply by 2.496). Broadband UV radiation provocation test results were positive for 112 patients (93%). In 28 patients (23%) with abnormal monochromator phototest findings, sensitivity occurred to UV-A, UV-B, and/or visible light, and UV-A of 350 ± 10 nm was the most prevalent wavelength. Photopatch test reactions were positive for 18 patients (15%). Patients with SPTs V to VI (31 [26%]) vs SPTs I to IV (89 [74%]) were younger at photosensitivity onset (median age, 24 years [IQR, 15-37 years] vs 40 years [IQR, 25-55 years]; P = .003), were more likely to be female (23 [74%] vs 46 [52%]; P = .03), and had a lower vitamin D status and a higher frequency of abnormal monochromator phototest findings.

Conclusions and Relevance

In this case series study, PAD affected patients with different ages and SPTs and was associated with substantially impaired quality of life. The findings suggest that confirming PAD through phototesting may provide better personalized care for patients through identification of provoking wavelengths, relevant photocontact allergies, and appropriate photoprotection advice.

Narrow-band phototherapy in the treatment of atopic dermatitis: mechanisms of action, methodology of implementation

Phototherapy is widely used to treat various chronic skin diseases. One of the most effective methods of treatment is narrow-band medium-wave ultraviolet radiation with a wavelength of 311 nm (UVB-311). UVB-311 is used for such immune-mediated diseases as atopic dermatitis, psoriasis, vitiligo, mycosis fungoides and others. Despite the fact that the method was developed more than 30 years ago, the exact mechanism of its therapeutic action remains insufficiently studied. To date, most of the effects of UVB-311 are explained by its effect on the immune cells of the skin. This review examines data on the effects on the main molecular targets, including T-lymphocytes, keratinocytes, Langerhans cells, cytokine profile, epidermal barrier proteins. Data on the features of the pathogenetic effect of UVB-311 on the immune mechanisms of pathogenesis in atopic dermatitis were obtained. The issues of dosing by determining the minimum erythemic dose (MED) or skin phototype, methodology of procedures are discussed. Prospects for further study of photobiological aspects of UVB-311 action are determined.

Long-wavelength ultraviolet A (UVA-1) phototherapy for the treatment of patients with atopic dermatitis

One of the methods of therapy for atopic dermatitis is long-wavelength ultraviolet therapy A (UVA-1- therapy). This review aims to provide the mechanisms of action of UVA-1-therapy an overview about the effectiveness of UVA-1-therapy in patients with atopic dermatitis taking into account factors that can affect the effectiveness of treatment radiation dose, skin phototype of patients, concomitant drug therapy. The available data on a decrease in the severity of atopic dermatitis as a result of the course of UVA-1-therapy and on a decrease in the severity of itching in patients are presented. The data on the rate of onset of the therapeutic effect of UVA-1-therapy and the duration of its maintenance are considered. The safety of UVA-1-therapy is discussed, and the most frequent undesirable effects a feeling of warmth, fever, itching, hyperpigmentation, are given. The possibility of developing side effects requiring discontinuation of treatment is assessed. The data obtained indicate the effectiveness and safety of the UFA-1-radiation in the treatment of patients with moderate-to-severe atopic dermatitis.

Filaggrin expression via immunohistochemistry in basal cell carcinoma and squamous cell carcinoma

BACKGROUND

Filaggrin is a protein integral to the structure and function of the epidermis. Filaggrin (FLG) loss-of-function (LOF) mutations are common and increase the risk of developing atopic dermatitis (AD) and ichthyosis vulgaris (IV). Epidemiologic data suggest a link between skin cancer and AD. We examined if FLG staining pattern can be used to characterize cutaneous squamous cell carcinomas (SCC), basal cell carcinomas (BCC), and reactive squamous epithelium.

METHODS

Tissue microarrays (TMAs) were created from 196 cases of formalin-fixed paraffin-embedded (FFPE) SCC and 144 BCC cases. TMAs and sections of reactive squamous epithelium were stained with optimized anti-FLG antibody and evaluated for FLG expression (normal, abnormal, or negative).

RESULTS

FLG was absent in poorly differentiated (PD) compared to well-differentiated (WD) SCC (P < .0001) and moderately-differentiated (MD) (P = .0231) SCC, and in MD compared to WD SCC (P = .0099). Abnormal staining was significantly increased in PD compared to WD cases (P = .0039) and in MD compared to WD cases (P = .0006). Most BCC did not exhibit FLG expression (P < .05). Reactive squamous epithelium demonstrated normal, but exaggerated FLG expression.

CONCLUSIONS

Our findings demonstrate the differences in FLG expression patterns in types of keratinocyte carcinomas and their mimickers.

ΔNp63 controls a TLR3-mediated mechanism that abundantly provides thymic stromal lymphopoietin in atopic dermatitis

In the skin lesions of atopic dermatitis (AD), keratinocytes release large quantities of thymic stromal lymphopoietin (TSLP), causing unfavorable inflammation along with skin damage. Nevertheless, how TSLP influences keratinocytes themselves is still unknown. In this study, we showed that ΔNp63, a p53-homologue, predominantly expressed in keratinocytes regulated the receptor complex of TSLP, which determines susceptibility to self-derived TSLP. Expression of TSLP receptors in skin tissues and keratinocytes was assessed by immunohistochemistry and quantitative RT-PCR, and in vitro studies were also performed to examine the functional relevance of ΔNp63 in the expression of TSLP receptors and the constituting autocrine and/or paracrine pathway of TSLP under the condition of stimuli to innate receptors sensing cell damage. The results showed that normal keratinocytes in the upper epidermis preferentially expressed TSLP receptors and conversely lacked ΔNp63, which has an inhibitory effect on the expression of TSLP receptors. Interestingly, the epidermis of AD lesions was found to abundantly contain keratinocytes with low or undetectable levels of ΔNp63 (ΔNp63(lo/-)). Moreover, in the absence of ΔNp63, keratinocytes readily presented TSLP and other cytokines by stimuli through Toll-like receptor 3 (TLR3). Together with the evidence that extrinsic TSLP itself augments TSLP production by keratinocytes without ΔNp63, the results indicate that ΔNp63(lo/-) keratinocytes generate TSLP through a putative autocrine and/or paracrine pathway upon TLR3 stimulation within AD lesions, since moieties of damaged cells and pathogens stimulate TLR3.

Vitamin D-deficient osteomalacia due to excessive self-restrictions for atopic dermatitis

A 34-year-old Japanese woman presented with a 2-year history of generalised bone pain, muscle weakness and gait disturbance. The patient had been following a restricted diet (without fish or dairy products) and avoiding ultraviolet exposure for 8 years to manage her worsening atopic dermatitis. Physical examination revealed generalised bone tenderness and bilateral symmetric proximal muscle weakness. Vitamin D-deficient osteomalacia was diagnosed based on the laboratory examination findings, which indicated high serum alkaline phosphatase, high intact parathyroid hormone, and low 25-hydroxyvitamin D levels. Her symptoms improved after oral active vitamin D and calcium administration. To the best our knowledge, this case is the first report of vitamin D-deficient osteomalacia in an adult patient due to excessive dietary restriction for managing atopic dermatitis. We emphasise the importance of increasing awareness of vitamin D deficiency as a risk factor for the development of osteomalacia, and caution against excessive avoidance of sun exposure and dietary restriction.

Knockdown of filaggrin impairs diffusion barrier function and increases UV sensitivity in a human skin model

Loss-of-function mutations in the filaggrin gene are associated with ichthyosis vulgaris and atopic dermatitis. To investigate the impact of filaggrin deficiency on the skin barrier, filaggrin expression was knocked down by small interfering RNA (siRNA) technology in an organotypic skin model in vitro. Three different siRNAs each efficiently suppressed the expression of profilaggrin and the formation of mature filaggrin. Electron microscopy revealed that keratohyalin granules were reduced in number and size and lamellar body formation was disturbed. Expression of keratinocyte differentiation markers and the composition of lipids appeared normal in filaggrin-deficient models. The absence of filaggrin did not render keratins 1, 2, and 10 more susceptible to extraction by urea, arguing against a defect in aggregation. Despite grossly normal stratum corneum morphology, filaggrin-deficient skin models showed a disturbed diffusion barrier function in a dye penetration assay. Moreover, lack of filaggrin led to a reduction in the concentration of urocanic acid, and sensitized the organotypic skin to UVB-induced apoptosis. This study thus demonstrates that knockdown of filaggrin expression in an organotypic skin model reproduces epidermal alterations caused by filaggrin mutations in vivo. In addition, our results challenge the role of filaggrin in intermediate filament aggregation and establish a link between filaggrin and endogenous UVB protection.

Throwing a light on photosensitivity in atopic dermatitis: a retrospective study

BACKGROUND

Photosensitivity in atopic dermatitis (AD) is a well known but ill-defined phenomenon.

OBJECTIVES

To determine the prevalence of photosensitivity in patients with AD, define its clinical characteristics, and analyze the photo provocation test (phototest) results.

METHODS

A retrospective study of patients with AD who were phototested because of suspected photosensitivity at our department during the period 1994-2004.

RESULTS

The total number of patients with AD seen in our department between 1994 and 2004 was 3804, of whom 145 patients (45 men and 100 women) were phototested. Photosensitivity was confirmed in 108 (74%) of these 145 patients (33 men and 75 women). The minimal erythema dose (MED) for UVB was decreased in eight of these 108 patients (7%) and the MED for UVA in five patients (5%). Two major clinical reaction patterns were observed: a polymorphic light eruption-type reaction in 51 patients (47%) and an eczematous reaction in 44 patients (41%). Seventy-two of the 108 patients (67%) had a pathologic reaction to UVA and UVB, 18 patients (17%) were only UVB sensitive, and 18 patients (17%) were only UVA sensitive. Photopatch tests were performed in 125 patients (86%). Twenty-nine patients (23%) had a positive photocontact reaction to one or more substances.

CONCLUSION

Photosensitivity is found in approximately 3% of patients with AD and the majority are female. Photosensitivity in patients with AD consists of two clinical reaction patterns distinguishable by phototesting. Patients were diagnosed with either AD and co-existing polymorphic light eruption or photosensitive AD.