Polymorphous Light Eruption

Skin microbiome dynamics in patients with polymorphic light eruption in response to ultraviolet radiation

BACKGROUND

Polymorphic light eruption (PLE) is the most frequent photodermatosis in Europe, with an estimated prevalence of 10-20%, particularly in temperate climates. Itching or burning lesions appear only in sun-exposed areas, predominantly on the chest, arms and forearms, within a few hours following exposure. The cause of the disease remains unknown, yet studies have suggested that microbial elements in the skin may play a role in its pathogenesis.

OBJECTIVES

To investigate the skin microbiome of a cohort of patients with PLE upon exposure to ultraviolet radiation (UVR), to assess its role in the onset of PLE lesions.

METHODS

Forty-one skin swabs were collected from 11 patients with PLE at baseline and after 3 days of exposure to UVR, and from healthy control participants. The collected swabs were analysed for their microbial composition using a 16S amplicon sequencing approach.

RESULTS

PLE skin showed a dysbalanced microbiome at baseline, with significantly reduced microbial diversity and noticeable colonization by bacterial pathogens, including Staphylococcus aureus. Upon UVR exposure, the PLE microbiome exhibited further loss of diversity and a reduction in beneficial skin commensals. In line with this, we found that UVR exerted strong antimicrobial effects in vitro against representative skin residents.

CONCLUSIONS

UVR can lead to profound changes in the skin microbiome, allowing the proliferation of dysbiotic members that can release a variety of elements able to trigger PLE lesions. This is the first study to investigate the cutaneous microbiome changes in patients with PLE upon UVR exposure, offering new insights into disease pathogenesis that has so far been unexplored.

Summer and spring elbow rashes is a variant of polymorphous light eruption: confirmation by photoprovocation and histopathology in a series of five cases

Background

Summer and spring eruptions on the elbows are a variant of polymorphous light eruption described on clinical and histopathological grounds; however, to our knowledge, they have not been confirmed by photobiological studies.

Objective

Based on photobiological studies, this study aimed to demonstrate the involvement of ultraviolet-A (UVA) radiation in this variant of polymorphous light eruption occurring exclusively on the elbows.

Methods

A series of five patients with polymorphous light eruption lesions on the elbows were included in our study. All patients underwent phototesting and photoprovocation of the skin lesions after exposure to a UVA light source [Philips UVA HPA lamp (400 W)]. All patients underwent punch biopsy and histopathological and immunohistochemical studies with anti-CD123.

Results

In all the cases, UVA irradiation caused the appearance of skin lesions on the elbows with characteristic polymorphous light eruption. Histological data showed edema in the superficial dermis and a perivascular lymphocytic infiltrate compatible with polymorphous light eruption. Immunohistochemical staining for CD1-23 showed negative results.

Conclusions

For the first time, photobiological photoprovocation studies demonstrated that repeated exposure to UVA radiation leads to the generation of skin lesions on the elbows, which are clinically and histologically consistent with summer and spring eruptions, confirming that elbow rash is a variant of polymorphous light eruption.

Demographics and clinical presentations of 844 patients with light and dark skin types with polymorphous light eruption and chronic actinic dermatitis evaluated over 23 years

INTRODUCTION

Polymorphous light eruption (PMLE) and chronic actinic dermatitis (CAD) have been classically described in White individuals, although recent studies have reported higher prevalence in patients with dark skin types, particularly African Americans.

OBJECTIVE

To evaluate for differences in demographic, and clinical features between persons with light and dark skin types who have PMLE and CAD.

METHODS

Retrospective review of patients with PMLE and CAD who were diagnosed from January 1, 1998, through November 31, 2021, at a single academic dermatology center.

RESULTS/DISCUSSION

A total of 844 patients (725 [85.9%] female; mean [SD] age of onset: 41.7 [16.9] years) were diagnosed with PMLE, and 60 patients (22 [36.6%] female; mean age, [SD]: 60.6 [10.6] years) of age at presentation, disease duration of 8.2 [7.3] years were diagnosed with CAD. Although just over 50% of the general clinic population was White, the prevalence of PMLE and CAD was significantly higher in dark-skinned individuals compared to light-skinned individuals (PMLE: 625 [74.0%] vs. 219 [25.9%], p value < .001; CAD: 43 [71.6%] vs. 17 [28.3%], p value = .003) respectively. The pinpoint papular variant of PMLE (PP-PMLE) was predominantly seen in dark-skinned individuals.

CONCLUSION

A substantial proportion of PMLE and CAD cases are present in dark-skinned individuals. PP-PMLE can be mistaken for lichen nitidus. As such, recognition of this entity is important for adequate evaluation and management of patients with PMLE.

Prevention of Polymorphic Light Eruption Afforded by a Very High Broad-Spectrum Protection Sunscreen Containing Ectoin

Introduction

Polymorphic light eruption (PLE) is the most common idiopathic, acquired photodermatosis. The pathophysiology of PLE is not yet fully understood but seems to involve immunological mechanisms, UVA-induced oxidative stress, and the subsequent elicitation of a cellular stress response affecting keratinocyte gene expression and skin immune function. In the present study, a high broad-spectrum sunscreen medical device (MD), containing a very high protection complex of UVB and UVA filters and ectoin, was investigated for its ability to protect against UVA-induced PLE.

Methods

The study was carried out as a monocentric, double-blinded, randomized, untreated controlled design. The test MD was applied (2 mg/cm²) on one side of the chest according to a randomization list of 15 patients with a typical history of PLE, and the contralateral area remained untreated. After product application, the test areas were exposed daily to increasing doses of UVA radiation (from 40 to 60 J/cm²) until a PLE reaction was detected or for a maximum of five consecutive days. Evaluations of induced PLE included clinical scoring and chromametry for erythema and pigmentation.

Results

Overall, no positive PLE reaction was observed on the side of the chest treated by the test MD, whereas positive PLE reactions were triggered on the untreated side of 13 subjects. Subjective sensations were very rare on the MD-treated side but were numerous and more severe on the untreated side. Chromametry and clinical visual inspection indicated that the skin color was unchanged on the MD-protected side, whereas high increased values of erythema and pigmentation were observed on the untreated chest side.

Conclusion

This MD sunscreen based on a complex of UVA–UVB filters and 1% of ectoin may be effective in preventing UVA-induced PLE. New studies comparing this MD sunscreen versus the same product without ectoin should be conducted.

ClinicalTrials.gov identifier: NCT05320315 (retrospectively registered 09/17/2021).

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-022-00755-5.

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.

Immunopathogenesis and management of polymorphic light eruption

Polymorphic light eruption (PLE) is the most common immunologically mediated photodermatosis, demonstrating many abnormalities caused by critical failure of ultraviolet (UV)-induced immunosuppression. The unique expression of antimicrobial peptides in PLE, which is most likely determined by alteration of microbiome components upon UV exposure, implicates their possible triggering role and pathogenic significance in the eruption. The review aims to clarify current knowledge regarding the immunological disturbances correlated with PLE that serve a base for better understanding of molecular pathogenesis of the disease and the development of new therapeutic strategies. Preventive treatment with broad-spectrum suncreens and sunscreens containing DNA repair enzymes, as well as natural photohardening with graduate exposure to sunlight in early spring could be sufficient in milder cases. Antioxidants and topical calcipotriol are promising approach for adjuvant prevention. Phototherapy, mainly with narrow band UVB rays, is more appropriate method in severe cases of the disease. The established treatment options for PLE include local and systemic glucocorticoids, systemic nonsedative antihistamines for itch relief, and rarely, immunosuppressive drugs in the refractory cases. Like medical photohardening, afamelanotide has the potential of photoprotection by inducing a melanization of the skin. Afamelanotide is believed to be a possible new treatment option for very severe and refractory cases of PLE. Targeting the main pruritogenic cytokine, IL-31, opens a new road for the development of novel therapeutic approaches to combat moderate and severe itching in cases of PLE with intense pruritus.