Polymorphous light eruption

Long-Term Course of Polymorphic Light Eruption: A Registry Analysis

Background: Little is known about the long-term course of polymorphic light eruption (PLE).

Objective: To predict disease course, a questionnaire was sent to patients whose PLE had been diagnosed between March 1990 and December 2018 and documented in the Austrian Cooperative Registry for Photodermatoses.

Methods: In January 2019, 205 PLE patients were contacted by mail and asked to complete a questionnaire on their disease course, including whether the skin's sun sensitivity had normalized (i.e., PLE symptoms had disappeared), improved, stayed the same, or worsened over time. Patients who reported normalization of sun sensitivity were asked to report when it had occurred.

Results: Ninety-seven patients (79 females, 18 males) returned a completed questionnaire. The mean (range) duration of follow-up from PLE onset was 29.6 (17–54) years for females and 29.4 (16–47) years for males. The disease disappeared in 32 (41%) females after 17.4 (2–41) years and in 4 (24%) males after 11.8 (5–26) years. Twenty-nine (37%) females and 6 (35%) males reported improvement of symptoms over time; 15 females (19%) and 7 males (41%) reported no change; and 3 females (4%) and no males reported worsening of symptoms. Kaplan-Meier analysis revealed that after 20 years 74% (95%CI, 64–82%) of patients still suffered from PLE. PLE lesion persistence (>1 week) tended to predict a prolonged course of PLE.

Conclusions: PLE usually takes a long-term course over many years though in most patients its symptoms improve or disappear over time. How improvement relates to the pathophysiology of the disease remains to be determined.

Polymorphous Light Eruption- An Indian Scenario

Polymorphous light eruption (PMLE) is the most common, idiopathic, acquired photodermatosis, characterized by abnormal, recurrent, and delayed reaction to sunlight. Polymorphous light eruption is common worldwide but the morphology, distribution, and pigmentary changes are unique in Indian skin which is discussed in this review. The prevalence of PMLE is around 10–20% in the general population. It commonly occurs in females between 20and 30 years of age. It is the most common photodermatosis in school-going children. Visible light sensitivity is an important phenomenon in PMLE. It typically presents as recurrent and chronic lesions over photoexposed sites. Initially, patchy erythema occurs with pruritus. Most of the Indians belong to type IV to type VI skin and pigmentary changes are commonly seen. The unique feature of PMLE in Indian skin is the pigmentary change which varies from hypopigmented to hyperpigmented lesions. These pigmentary changes may occur alone or in combination with erythematous or skin-colored lesions. The pigmentary lesions are seen in more than 50% of lesions. The histopathology of PMLE is characterized by the presence of hyperkeratosis, spongiosis with or without the presence of liquefactive degeneration in the epidermis. Dermal changes in the upper and mid dermis include the presence of dense perivascular lymphocytic infiltrate. The management of PMLE includes both preventive measures and medical management. Topical sunscreens, topical steroids, hydroxychloroquine and antioxidants play a very important role.

Cutaneous infiltration of plasmacytoid dendritic cells and T regulatory cells in skin lesions of polymorphic light eruption

BACKGROUND

Polymorphic light eruption (PLE) is the most common autoimmune photodermatosis. Plasmacytoid dendritic cells (PDCs) are important mediators of innate antimicrobial immunity involved in the pathogenesis of many inflammatory skin diseases. In addition to PDCs, regulatory T cells (Tregs) are involved in controlling inflammation and adaptive immunity in skin by their immunosuppressive capacity.

OBJECTIVE

The aim of this study was to investigate the presence of PDCs and Tregs in photoexposed skin from PLE compared to healthy skin.

METHODS

Patients with PLE diagnosis and healthy controls were recruited and underwent a photoprovocative test. A 4-mm punch biopsy was taken from the site of positive photoprovocation test reaction, and immunohistochemistry for BDCA2 as marker for PDCs, CD4 and FOXP3 as markers for Tregs was performed. Double immunostain for FOXP3 and CD4 was performed as well. Absolute counts for CD4, BDCA2 and FOXP3 were performed in at least 5 High Power Fields (HPF). Percentage of CD4-, BDCA2- and CD4FOXP3-positive cells over the total inflammatory infiltrate was assessed for each case.

RESULTS

We enrolled 23 patients and controls. BDCA2+ cells were present in 91.3% of PLE skin samples and 100% of healthy volunteer. Both in PLE patients and healthy controls, PDCs distribution was mainly dermic (P < 0.05). Compared to healthy controls, both epidermic and dermic BDCA2+ cells count were significantly higher in PLE patients (P < 0.05). Both in PLE patients and healthy controls, Tregs distribution was mainly dermic (P < 0.05). The presence of both CD4+ cells and FOXP3+ cells was significantly higher in the dermis of PLE patients compared to controls (P < 0.05). Relative percentages of cellular infiltrations confirmed these results.

CONCLUSIONS

D-PDCS and Tregs may play a significant role in the development of PLE, and dermal distribution of PDCs in PLE skin biopsies seems to confirm a possible overlap with cutaneous lupus erythematosus (CLE).

Polymorphous Light Eruption

Polymorphous light eruption (PLE) is the commonest immuno-mediated photodermatosis. It occurs after solar or artificial UV-light exposure and affects only the sun-exposed areas with preference of the V-area of the chest, of arms and forearms, legs, upper part of the back, and rarely the face. The lesions are itching or burning, and vary morphologically from erythema to papules, vesico-papules and occasionally blisters, plaques, sometimes erythema multiforme-like, insect bite-like wheals and purpura. The clinical manifestations befall within a few hours to days from light exposure, last a few days, and subside in about a week without sequelae. Its diagnosis is based on history, morphology and phototests. PLE is considered as a delayed hypersensitivity response to newly UV induced, but still unidentified, antigen(s). Usually, MED is normal, but the provocative phototests with UVA or UVB reproduce the spontaneous lesions in about 50% of the patients. Broad spectrum sunscreens and antioxidants, photohardening with PUVA or narrow band UVB may be beneficial to prevent the disease. Therapy is based mainly on topical or systemic corticosteroids.

Influence of the season on vitamin D levels and regulatory T cells in patients with polymorphic light eruption

The exact mechanisms of photohardening in polymorphic light eruption (PLE) are still unknown, but medical photohardening was shown to increase regulatory T cell (Treg) numbers in the blood of PLE patients, similar to natural hardening. Furthermore, oral vitamin D supplementation increased peripheral Tregs in healthy individuals. We herein report on a post hoc analysis of 26 screened PLE patients of a clinical trial (ClinicalTrials.gov No. NCT01595893), in which the influence of the progressing season was investigated on baseline CD4+CD25+FoxP3+CD127- Treg numbers by flow cytometry and Treg suppressive function by co-culture assays with T effector cells as a secondary endpoint, together with 25-hydroxy vitamin D (25(OH)D) serum levels at the study's screening visit, taking place in the period from January to June. The mean 25(OH)D serum level of all patients was 33.2 ng ml(-1). Ten of those patients (38.5%) were identified with low 25(OH)D levels (<30 ng ml(-1)). Significantly higher baseline 25(OH)D serum levels (plus 34.4%; P = 0.0182) as well as higher relative Treg percentages in CD4+ population (plus 62.8%; P = 0.0157) and in total lymphocyte population (plus 59.6%; P = 0.0372) and higher absolute Treg numbers (plus 100.2%; P = 0.0042) were observed in the late spring/early summer period (April to June) compared to the winter period (January to February). No significant relationship was observed when Treg numbers and function were correlated with 25(OH)D levels. These data indicate that in PLE patients Treg numbers and their suppressive function are independent of vitamin D serum levels and suggest that UV light and/or other seasonal factors may affect these cells via the non-vitamin D related pathway(s).

Levels and function of regulatory T cells in patients with polymorphic light eruption: relation to photohardening

Background

We hypothesized that regulatory T cells (Tregs) are involved in the immunological abnormalities seen in patients with polymorphic light eruption (PLE).

Objectives

To investigate the number and suppressive function of peripheral Tregs in patients with PLE compared with healthy controls.

Methods

Blood sampling was done in 30 patients with PLE [seeking or not seeking 311‐nm ultraviolet (UV)B photohardening] as well as 19 healthy controls at two time points: TP1, March to June (before phototherapy); and TP2, May to August (after phototherapy). We compared the number of CD4⁺CD25^highCD127⁻FoxP3⁺ Tregs by flow cytometry and their function by assessing FoxP3 mRNA levels and effector T cell/Treg suppression assays.

Results

Tregs isolated from healthy controls significantly suppressed the proliferation of effector T cells at TP1 by 68% (P = 0·0156). In contrast, Tregs from patients with PLE entirely lacked the capacity to suppress effector T‐cell proliferation at that time point. The medical photohardening seen in 23 patients with PLE resulted in a significant increase in the median percentage of circulating Tregs [both as a proportion of all lymphocytes; 65 6% increase (P = 0·0049), and as a proportion of CD4⁺ T cells; 32.5% increase (P = 0·0049)]. This was accompanied by an increase in the expression of FoxP3 mRNA (P = 0·0083) and relative immunosuppressive function of Tregs (P = 0·083) comparing the two time points in representative subsets of patients with healthy controls tested. Seven patients with PLE not receiving 311‐nm UVB also exhibited an increase in the number of Tregs but this was not statistically significant. No significant differences in Treg numbers were observed in healthy subjects between the two time points.

Conclusions

An impaired Treg function is likely to play a role in PLE pathogenesis. A UV‐induced increase in the number of Tregs (either naturally or therapeutically) may be a compensatory mechanism by which the immune system counteracts the susceptibility to PLE.

What's already known about this topic?

Patients with polymorphic light eruption (PLE) display immunological abnormalities.

Previous studies have shown that they are resistant to the immune suppressive effects of sunlight.

What does this study add?

We found that the number and suppressive function of regulatory T cells (Tregs) are crucial in the pathogenesis of PLE.

An increase in Treg levels (after photohardening) might be a compensatory mechanism by which the immune system intends to counteract the susceptibility to PLE formation.

Polymorphous light eruption: clinic aspects and pathogenesis

Polymorphous light eruption is an immunologically mediated photodermatosis with high prevalence, particularly among young women in temperate climates, characterized by pruritic skin lesions of variable morphology, occurring in spring or early summer on sun-exposed body sites. A resistance to ultraviolet radiation (UVR)-induced immunosuppression and a subsequent delayed-type hypersensitivity response to a photoantigen have been suggested as key factors in the disease. Molecular and immunologic disturbances associated with disease pathogenesis include a failure of skin infiltration by neutrophils and other regulatory immune cells on UVR exposure linked to a disturbed cytokine microenvironment. Standard management is based on prevention.

UV emissions from low energy artificial light sources

Energy efficient light sources have been introduced across Europe and many other countries world wide. The most common of these is the Compact Fluorescent Lamp (CFL), which has been shown to emit ultraviolet (UV) radiation. Light Emitting Diodes (LEDs) are an alternative technology that has minimal UV emissions. This brief review summarises the different energy efficient light sources available on the market and compares the UV levels and the subsequent effects on the skin of normal individuals and those who suffer from photodermatoses.

Patients with polymorphic light eruption have decreased serum levels of 25-hydroxyvitamin-D3 that increase upon 311 nm UVB photohardening

BACKGROUND

Polymorphic light eruption (PLE) is a very common condition whose pathogenesis may involve immunological abnormalities. Vitamin D sufficiency is thought to be important for normal immune function.

OBJECTIVE

To determine whether PLE patients are vitamin D deficient and to study how photohardening with 311 nm UVB affects the vitamin D status of PLE patients.

METHODS

The vitamin D status of 23 PLE patients (21 females and 2 males; age range, 18-55 years) was analysed at four different time points (early spring, late spring, summer, and winter) by measuring 25-hydroxyvitamin-D(3) (25(OH)D) serum levels through a standardised immunoassay. Fifteen of those patients received 311 nm UVB in early spring for prevention of PLE symptoms. 25(OH)D levels of the PLE patients were compared to that of 23 sex-, age-, and body-mass-index post hoc-matched control subjects.

RESULTS

PLE patients had low levels of 25(OH)D throughout the year compared to that of the control subjects. At baseline in early spring, the mean ± SD 25(OH)D level was 14.9 ± 3.0 ng ml(-1) in the PLE patients that would later receive 311 nm UVB and 14.4 ± 2.4 ng ml(-1) in the patients not receiving 311 nm UVB. Successful prophylactic treatment with 311 nm UVB significantly increased 25(OH)D levels to a mean of 21.0 ± 3.4 ng ml(-1) (p < 0.001; ANOVA, Tukey's test). Heading into summer, the 25(OH)D levels in treated patients decreased again, reaching their lowest levels in winter. In contrast, the 25(OH)D levels of untreated PLE patients stayed in the low range in early and late spring but increased by trend towards summer, reaching similar levels to that of the PLE patients who had received 311 nm UVB (17.1 ± 2.3 vs. 17.3 ± 6.0 ng ml(-1)). Like the treated PLE patients, 25(OH)D levels of untreated patients significantly decreased in winter to comparable levels (12.2 ± 1.9 vs. 13.8 ± 1.8 ng ml(-1)). Taken together, the 25(OH)D levels of PLE patients were significantly lower at all time points than that observed in the matched control population (34.4 ± 12.5 ng ml(-1)) (p < 0.000003).

CONCLUSIONS

PLE patients have low 25(OH)D serum levels. 311 nm UVB phototherapy that prevented PLE symptoms increased those levels. Thus, we speculate that boosting levels of vitamin D may be important in ameliorating PLE.

GSTM1, GSTT1 and GSTP1 gene polymorphism in polymorphous light eruption

BACKGROUND

Polymorphous light eruption (PLE) is the most common chronic and idiopathic photodermatosis. PLE is assumed to represent an immunological hypersensitivity reaction to a radiation-induced cutaneous antigen involving reactive oxygen species (ROS) on the basis of a genetic predisposition. Among others, cellular protection against ROS is provided by glutathione S-transferases (GSTs). Different variants of the GST enzymes may influence the activity and efficiency of detoxification and biotransformation of unknown UV-induced skin-antigens and other factors that may play an important role in the pathogenesis of PLE.

METHODS

In this study the relationship between isoenzymes of the GST genes GSTM1, GSTT1 and GSTP1 and possible protective or predisposing effects on PLE was examined in 29 patients and 144 controls. Diagnosis of PLE was based on the presence of characteristic clinical features.

RESULTS

No association between the functional polymorphisms of the GST gene family and PLE was found. Prevalence of certain GST isoenzymes or polymorphisms in patients with PLE did not differ from healthy controls.

CONCLUSION

Our data do not support prevalence of GST isoenzymes or polymorphisms as a protective effect against PLE. Especially a higher carrier frequency of GSTP1 Val(105) as a protective factor against PLE which has been published before could not be proved. The GST genotypes GSTM1, GSTT1 and GSTP1 (including SNPs) seem to have no relevant association with PLE.

New insights into the mechanisms of polymorphic light eruption: resistance to ultraviolet radiation-induced immune suppression as an aetiological factor

An abnormal immune response has long been thought responsible for the patho-aetiology of polymorphic light eruption, the most common photodermatosis. Recent evidence indicates that polymorphic light eruption patients are resistant to the immune suppressive effects of sunlight, a phenomenon that leads to the formation of skin lesions upon seasonal sun exposure. This immunological abnormality in polymorphic light eruption supports the concept of the biological significance and evolutionary logic of sunlight-induced immune suppression, i.e. the prevention of immune responses to photo-induced neo-antigens in the skin, thereby preventing autoimmunity and skin rashes. This article focuses on the immunological alterations in polymorphic light eruption and the pathogenic significance to the disease state and skin carcinogenesis.

Prevalence of photodermatosis in four regions at different altitudes in Yunnan province, China

Idiopathic photodermatoses are common diseases in dermatology clinics that are associated with ultraviolet (UV) irradiation. The group includes a few dermatoses such as polymorphous light eruption (PLE) and chronic actinic dermatitis (CAD). The prevalence of PLE and CAD in China has not been previously reported. To investigate the population-based prevalence of polymorphous light eruption (PLE) and chronic actinic dermatitis (CAD) in six minority groups living in four regions with significantly different altitudes in the Yunnan province, a questionnaire survey was administered to 4899 residents of random villages in Yuanjiang county (Dai and Hani minorities), Kunming city (Han people and Yi minority), Lijiang county (Naxi minority), and Shangri-La county (Zang minority). The altitudes of these counties are 380 m, 1870 m, 2410 m and 3280 m a.s.l., respectively. The results showed that, first, there were 2400 males (49.0%) and 2499 females (51.0%). The prevalence of PLE was 0.65% (32/4899), and the prevalence of CAD was 0.18% (9/4899). PLE was higher among females than males (3.8 vs 1, P < 0.01). The CAD prevalence was not significantly different between males and females (1.6 vs 1, P > 0.05). Second, the prevalence of PLE was increased in higher elevations regions compared to lower elevations (P < 0.01). However, the prevalence of CAD was not significantly different among the four regions (P > 0.05). Third, the mean times of sun exposure for PLE and CAD were 6.0 and 6.5 h/day, respectively. The mean durations of PLE and CAD were 5.8 years, and 6.6 years, respectively. The study demonstrated that the prevalence of PLE is higher than that of CAD in Yunnan, and that the prevalence of PLE is correlated with altitude.

Normalized ultraviolet (UV) induction of Langerhans cell depletion and neutrophil infiltrates after artificial UVB hardening of patients with polymorphic light eruption

BACKGROUND

Ultraviolet (UV) B hardening has been widely used as a prophylactic treatment in patients with polymorphic light eruption (PLE). Recent investigations have shown that in patients with PLE Langerhans cells (LCs) and neutrophils display less migration from and to the epidermis after an intense UVB irradiation compared with controls.

OBJECTIVES

To investigate the effect of UVB hardening of patients with PLE on their cell migratory responses after intense UVB exposure.

METHODS

Thirteen patients with PLE were recruited and UVB provocation testing was performed before entering the study. Among these patients, seven developed PLE rash upon UVB provocation ('UVB-P') and the other six did not respond ('UVB-NP'). Eleven age/sex-matched controls were included. Buttock skin of all included individuals was exposed to 6 minimal erythema doses (MED) of UVB (TL-12 lamps). Biopsies were taken after 24 h and 48 h, together with one control biopsy of unirradiated skin. Patients received total-body UVB hardening therapy consisting of 12 irradiations, on average rising from 10% to 140% of the initial MED in 6 weeks. Subsequently, MEDs were reassessed and biopsies were taken from newly irradiated (6 MED UVB) and unirradiated buttock skin. Skin sections were stained for the presence of LCs, macrophages and neutrophils. The cross-sectional area (in percentage) of positively stained cells within the epidermis was assessed from patients before and after hardening and compared with controls.

RESULTS

Before therapy, epidermal LC depletion and neutrophil influx at 48 h after 6 MED were most significantly reduced in 'UVB-P' patients (P = 0.025 and P =0.006, respectively) when compared with controls. 'UVB-NP' patients did not differ significantly from controls. After therapy, there were no longer any significant differences in the cell numbers among these three groups.

CONCLUSIONS

UVB hardening significantly improves UV-induced cell migratory responses in patients with PLE. UVB provokability of PLE appears to be most strongly linked to reduced UVB-induced trafficking of LCs and neutrophils, and 'UVB-P' patients show normalization of these responses after UVB hardening.