Safe, mild ultraviolet-B exposure: An essential human requirement for vitamin D and other vital bodily parameter adequacy: A review.

The enigma of skin sunburning, skin ageing and skin cancer and essential vitamin D production both resulting from solar ultraviolet-B (280-315 nm) (UVB) exposure has long puzzled photobiologists. Advice to patients by non-photobiological clinicians is now often to sunbathe to acquire vitamin D adequacy. However, modern work shows only mild UVB exposure is needed to maintain satisfactory levels, which have been demonstrated as very similar in summer and winter from about 25° to 70° north. Even very careful high protection factor 15 sunscreen use does not prevent adequate production, although it is slightly reduced, such that obsessive use of very protective screens of 50 + might. Dark skin pigmentation too usually at most minimally impairs production. However, confinement indoors and widespread clothing cover can, but oral supplementation overcomes any such deficiency. Thus, vitamin D adequacy needs just mild regular UVB skin exposure well under sunburning levels, unlikely to cause significant skin damage. This suggests mild UVB exposure may also be needed for other bodily requirements, which is indeed so. Thus, it also prevents the development of contact dermatitis and polymorphic light eruption through suppressing adaptive immunity. It also prevents the occurrence of multiple skin infections resulting from this suppression through stimulating innate immunity and cutaneous bacterial defensin production. Finally, blood pressure is reduced through low-dose UVB-induced production of the vasodilator nitric oxide (though UVA, 315-400 nm, is more efficient). Thus, mild UVB exposure is important for several aspects of internal health, whereas high-dose exposure is extremely detrimental to cutaneous health.

The quality of life of 790 patients with photodermatoses.

BACKGROUND: Polymorphic light eruption and erythropoietic protoporphyria (EPP) have been demonstrated to have a moderate and large impact on the quality of life (QoL) of patients, respectively. However, there is little information available about the impact of other photodermatoses on QoL. OBJECTIVES: To assess and compare the impact of all forms of photodermatoses on patients' QoL using the standard 1-week Dermatology Life Quality Index (DLQI) questionnaire and a modified questionnaire to assess the impact over the previous year. METHODS: All patients with photodermatoses seen between 2001 and 2005 at five U.K. photobiology centres were contacted by post on the same day during a forecasted sunny week across the U.K. and asked to complete DLQI questionnaires. RESULTS: A total of 1877 patients were contacted. Seven hundred and ninety-seven (42%) patients replied, with a range from 30% to 48% for the five individual centres. Nearly two-thirds of patients with actinic prurigo (AP) and more than one-third of patients with photoaggravated dermatoses (PAD), chronic actinic dermatitis, EPP and solar urticaria had a DLQI of > 10, confirming a very large effect of the disorders on QoL. Of the cutaneous porphyrias, both variegate porphyria (median DLQI 3) and porphyria cutanea tarda (median DLQI 1.5) had a much lower impact on QoL than EPP. CONCLUSION: This is the first large-scale study to attempt to measure the impact of a range of photodermatoses on QoL. Photodermatoses have a major impact on QoL. This impact is highest in AP and PAD.

Audit of the use of psoralen photochemotherapy (PUVA) and narrowband UVB phototherapy in the treatment of psoriasis.

BACKGROUND: Psoralen photochemotherapy (PUVA), the combined use of psoralen and long wave ultraviolet (UVA) irradiation, was introduced around 1974 and its beneficial effects were rapidly confirmed worldwide. In an attempt to minimize its recognized long-term photocarcinogenic risk after some 150-200 exposures while also maintaining efficacy, however, the narrowband (311-312 nm) ultraviolet B (UVB) lamp (TL-01) was introduced in 1984, and has moved towards replacing PUVA except for severe or resistant disease. AIMS: To discover whether our use of these therapies complied with established British Photodermatology Group guidelines for PUVA and guidelines formulated within our unit for narrowband UVB. METHODS: The study was retrospective over 6 months from November 2001 to April 2002, all relevant information being obtained from the patients' hospital notes. RESULTS: Thirty-one patients received PUVA (18 oral, 11 bath and two uncertain because of missing notes) and 20 narrowband UVB during this period. CONCLUSIONS: Our PUVA and narrowband UVB phototherapy guidelines were shown to have been followed relatively closely with the following exceptions: one PUVA patient received a high cumulative exposure by mutual agreement because there was no other suitable therapy; a failure to measure minimal phototoxic doses (MPDs) in some PUVA patients; and slightly prolonged referral delays, but generally by patient choice.

Skin surface glycerol levels in acne vulgaris.

Free glycerol would be expected from biochemical considerations to be an end product of lipolysis of sebum triglycerides. Glycerol was measured in skin surface washings of acne vulgaris patients, in acne vulgaris patients treated for at least 3 mo with oral tetracycline and in control subjects. Surface glycerol in untreated acne subjects was significantly less than that expected theoretically, whereas the amounts of such glycerol in treated acne patients and in control subjects closely approached the theoretically expected values. It is suggested that glycerol may be an in vivo substrate for Propionibacterium acnes.

Genetic modeling of abnormal photosensitivity in families with polymorphic light eruption and actinic prurigo.

Actinic prurigo and polymorphic light eruption are two of the so-called idiopathic photodermatoses, resulting from abnormal cutaneous responses to ultraviolet radiation (photosensitivity). Whereas they are clinically distinct in most cases, there are sufficient similarities between them to suggest they may be related conditions. To take this further, we examined the prevalence of polymorphic light eruption in families ascertained through actinic prurigo probands, as evidence of a shared pathogenesis. We then determined the heritability of photosensitivity in 420 individuals from families ascertained through polymorphic light eruption and actinic prurigo probands using segregation analysis. Across 58 pedigrees the prevalence of photosensitivity in first-degree relatives was 20.9% compared with a population prevalence of 13.6%, giving a relative risk of 1.5 (confidence interval 1.15-2.0) and providing evidence of clustering within families. The prevalence of photosensitivity (predominantly polymorphic light eruption) in relatives of actinic prurigo probands was 23.7%, with a relative risk of 1.74 (confidence interval 1.24-2.36). Modeling for polymorphic light eruption across all pedigrees revealed a strong genetic component with polymorphic light eruption showing a dominant mixed mode of inheritance. The model parameters estimate that 72% of the U.K. population carry a low penetrance polymorphic light eruption susceptibility allele, but that among this highly prevalent genotype only 24% of susceptible females and 13% of susceptible males will have polymorphic light eruption. Expression of polymorphic light eruption in genetically susceptible individuals (intergenotype variance) is determined in large part by a polygenic component, with an important additional environmental component. In summary, this study provides clear evidence that polymorphic light eruption is an inherited condition. It also suggests that polymorphic light eruption and actinic prurigo share a common genetic background, supporting the view that actinic prurigo may represent a human leukocyte antigen-restricted subset of polymorphic light eruption.

Immunologic differentiation of the Sézary syndrome due to cutaneous T-cell lymphoma and chronic actinic dermatitis.

Peripheral blood mononuclear cells from two well-defined groups of patients with the Sézary syndrome have been studied employing indirect immunofluorescent and indirect immunogold techniques in light and electron microscopy, using monoclonal antibodies against T-cell subpopulations. Four patients had chronic actinic dermatitis (CAD) of the actinic reticuloid variant, with erythroderma. Eight patients had cutaneous T-cell lymphoma. All patients showed the clinical features of the Sézary syndrome, including erythroderma, palmoplantar hyperkeratosis, and peripheral lymphadenopathy, and in all patients significant numbers (0.5-30.5 X 10(9) cells/liter) of circulating mononuclear cells were observed with Sézary cell morphology on light-microscopic examination of blood films. Major differences were observed in the circulating T-cell subpopulations in the two groups. In the erythrodermic CAD patients, there was a moderately elevated T-cell count (1.6 +/- 0.6 X 10(9) cells/liter; normal, 1.0 +/- 0.3 X 10(9) cells/liter) of which the majority of the cells was suppressor T cells (OKT8+) giving a very low helper:suppressor T-cell ratio of 0.1:1-0.36:1 (normal, 1.7:1-3.5:1). In cutaneous T-cell lymphoma, there was also an elevation of the T-cell count (9.5 +/- 12.9 X 10(9) cells/liter), but in these patients the predominant cell was the helper T cell (OKT4+) with a high helper:suppressor T-cell ratio of 3.7:1-98:1.

Homozygous variegate porphyria: identification of mutations on both alleles of the protoporphyrinogen oxidase gene in a severely affected proband.

Homozygous variegate porphyria is a severe skin and neurologic disease manifesting in early infancy, and characterized by markedly reduced levels of the penultimate enzyme in the heme biosynthetic pathway, protoporphyrinogen oxidase. We investigated the molecular basis of variegate porphyria, usually an autosomal dominantly inherited trait, in a severely affected female proband and her parents. The mutation detection strategy included heteroduplex analysis, automated sequencing, and allele specific oligonucleotide hybridization. We identified two underlying missense mutations in the protoporphyrinogen oxidase gene, consisting of a G-to-A transition in exon 6 (G169E), and a G-to-A transition in exon 10 (G358R). Our study establishes the molecular basis of "homozygous" variegate porphyria for the first time, in demonstrating that this patient is a compound heterozygote for two different missense mutations in the protoporphyrinogen oxidase gene.

Genetic heterogeneity in erythropoietic protoporphyria: a study of the enzymatic defect in nine affected families.

Erythropoietic protoporphyria (EPP) is associated with a deficiency of protohaem ferrolyase. We have used a novel assay for this enzyme based on its ability to utilize zinc as a substrate to investigate the inheritance of EPP in nine affected families. Zinc chelatase activity was markedly reduced in peripheral blood mononuclear cells from 14 EPP patients (mean, 3.3 nmol Zn protohaem/h/mg protein; range, 0.3-8.0) when compared with 41 controls (16.8 +/- 3.6) p less than 0.01. In three families with parent-to-child transmission of disease, the asymptomatic parent had an enzymatic activity within the normal range. In three pedigrees where the parents were asymptomatic, enzymatic activities were below the 95% confidence limits in both. Zinc chelatase activity was below the mean control value in 17 of the 18 parents in nine affected pedigrees, and six of seven asymptomatic offspring of patients with protoporphyria. The findings suggest that EPP is not transmitted as a simple dominant trait and that inheritance of more than one gene may be required for disease expression.

Photoprotection and 5-MOP photochemoprotection from UVR-induced DNA damage in humans: the role of skin type.

Sites on previously unexposed buttock skin in 18 subjects (skin types I-V) were treated daily for 2 weeks with suberythemogenic doses of solar-simulated radiation (SSR) alone, SSR plus a UVB sunscreen, and SSR plus the same sunscreen with 5-methoxypsoralen at 30 ppm. The three sites of treatment (designated SSR, SSR/S, and SSR/S/5-MOP), and a control site that received no SSR or topical treatment, were challenged with 2MED SSR 1 week after the treatment had ceased. Biopsy samples, taken within 15 min after the challenge dose, were assessed for unscheduled DNA synthesis (UDS, interpreted as a measure of DNA damage), melanin deposition, and stratum corneum thickening. Within a given skin type, when compared with controls, the significant increase in either pigmentation or stratum corneum thickening was similar for SSR and SSR/S/5-MOP. SSR/S inhibited these endpoints. Compared with controls, UDS was significantly reduced in skin types III-V by SSR and in all skin types by SSR/S/5-MOP. SSR/S elicited no effect apart from minimal reductions in skin types IV and V. Thus, the increases in pigmentation and stratum corneum thickening seen in all skin types with SSR and SSR/S/5-MOP were accompanied by reduced UDS in all skin types with SSR/S/5-MOP but only in skin types III-V with SSR. These findings suggest that, although induced pigmentation and stratum corneum thickening may account in part for the reduction of UDS, qualitative differences in induced pigmentation may exist in skin types I-II between SSR and SSR/S/5-MOP treatments. The findings can also be interpreted to indicate that SSR/S/5-MOP treatment can afford protection against DNA damage from subsequent exposure to solar ultraviolet radiation. Risk-benefit considerations on the use of sunscreens with and without 5-MOP are discussed and the conclusion is drawn that the judicious use of 5-MOP sunscreens, particularly in skin types I-II, affords an alternative option to those seeking a suntan.

Adhesion molecule expression in polymorphic light eruption.

Endothelial leukocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) are cytokine-regulated cell-surface leukocyte adhesion molecules. We have investigated the in vivo kinetics and pattern of expression of these adhesion molecules in relation to tissue accumulation of leukocytes in the photodermatosis, polymorphic light eruption (PMLE), which is characterized by dense perivascular leukocytic infiltration. Immunohistology was performed on biopsies taken at varying time points from PMLE lesions induced in 11 subjects by suberythemal solar simulated irradiation. Vascular endothelial ELAM-1 expression was first observed at 5 h, maximal at 24 to 72 h, and remained elevated at 6 d. VCAM-1, minimally expressed in control skin, was induced above background levels on endothelium and some perivascular cells after 24 h and maintained at 6 d. Endothelial cell ICAM-1 expression was increased above control levels at 72 h and 6 d. Keratinocyte ICAM-1 expression, most marked overlying areas of dermal leukocytic infiltration, began at 5 h and was strong at 72 h and 6 d. In addition to lymphocytes, significant numbers of neutrophils but not eosinophils were detected in the dermal leukocytic infiltrate that appeared at 5 h and persisted at 6 d. The pattern of adhesion molecule expression that we have observed is similar to that seen in normal skin during a delayed hypersensitivity reaction. These observations support an immunologic basis for PMLE.

The in situ repair kinetics of epidermal thymine dimers and 6-4 photoproducts in human skin types I and II.

We assessed the in situ time-dependent loss of epidermal thymine dimers and 6-4 photoproducts in skin types I and II after exposure to two minimal erythema doses of solar-simulating radiation on previously unexposed buttock skin. Using quantitative image analysis, we evaluated biopsy sections stained with monoclonal antibodies. We then made comparisons, in the same volunteers, with unscheduled DNA synthesis, which is a direct marker of overall excision repair. Removal of thymine dimers was slow (half-life = 33.3 h), with high levels of lesions still present 24 h post-irradiation; some lesions were still present at 7 d. In contrast, removal of 6-4 photoproducts was rapid (half-life = 2.3 h), the decay kinetics of which correlated better with the decline in epidermal unscheduled DNA synthesis (half-life = 7.1 h). These data show that as in mouse, monkey, and in vitro models, the 6-4 photolesion is repaired preferentially in human epidermis in situ. They also raise the possibility that poor thymine dimer repair may be a feature of skin types I and II, who are more prone to skin cancer than are types III and IV. There was an inverse relationship between the onset of erythema and 6-4 photoproduct repair, suggesting that this repair process initiates erythema.

HLA-DR4 may determine expression of actinic prurigo in British patients.

Human leukocyte antigen (HLA) associations have been reported in Amerindian patients with actinic prurigo. To determine if similar associations are present in the British Caucasoid population with actinic prurigo, 26 patients underwent serological typing for HLC Class I and II antigens. DNA analysis by both sequence-specific priming and group-specific amplification with single-stranded oligonucleotide probe hybridization was used to confirm the DR and DQ typing and to perform DR4 subtyping. All patients were DR4 positive, and 25 of 26 patients were DQ7 positive. DR4 subtyping revealed 12 of 20 patients tested to be DRB1*0407. A nonsignificant association was also found with HLA B55 that is in linkage disequilibrium with DRB1*0407. No HLA associations were found in 25 British Caucasoid patients with polymorphic light eruption. DRB1*0407 is rare in European Caucasoids without actinic prurigo, and HLA-DR4 may have an important role in determining expression of this disease.

Immune function, mutant frequency, and cancer risk in the DNA repair defective genodermatoses xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy.

There is evidence for defective DNA repair in xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy, but for increased cancer risk only in xeroderma pigmentosum. Natural and adaptive immune surveillance and mutant frequency to 6-thioguanine resistance in circulating T-lymphocytes were studied in five patients with xeroderma pigmentosum, two with Cockayne's syndrome, and one with trichothiodystrophy. Forty-eight-hour cutaneous hypersensitivity responses to recall antigens excluded anergy and circulating CD3+, CD4+, CD8+, and CD16+ cell numbers were within normal limits in all patients tested, as were proliferative lymphocyte responses to PHA, except in the trichothiodystrophy patient. Proliferative responses to recall antigens (PPD, SKSD, and Candida) showed that all patients responded to one or more antigens. Direct natural killer cytotoxicity measured against the human erythromyeloid leukaemia cell line K562 using a 4-h 51Cr release assay was significantly reduced in xeroderma pigmentosum (specific cytotoxicity less than mean +/- SD greater than 17.4 +/- 9.4 per cent, with effector:target cell ratio of 50:1) compared to normal controls (45.8 +/- 17.8), but normal in Cockayne's syndrome and trichothiodystrophy. Generation of lymphokine activated killer cell activity was normal in the two xeroderma pigmentosum lines tested. The mutant frequency in the xeroderma pigmentosum donors was significantly increased (p less than 0.01) and was elevated in the two Cockayne's syndrome donors, taking age into account. No mutants were observed from the single trichothiodystrophy donor. These findings suggest that reduced natural killer cell activity may contribute to the greatly increased susceptibility to skin cancer in xeroderma pigmentosum.

Increased concentrations of arachidonic acid, prostaglandins E2, D2, and 6-oxo-F1 alpha, and histamine in human skin following UVA irradiation.

The buttock skin of clinically normal human subjects was subjected to approximately 2.5 minimal erythema doses of ultraviolet A irradiation. Deep red erythema developed during irradiation, faded slightly within the next few hours, increased to maximum intensity between 9-15 h, and decreased gradually thereafter although still persisting strongly at 48 h. Suction blister exudates were obtained at 0, 5, 9, 15, 24, and 48 h after irradiation as well as suction blister exudates from a contralateral control site and assayed for arachidonic acid, prostaglandins D2 and E2, and the prostacyclin breakdown product 6-oxo-prostaglandin F1 alpha by gas chromatography-mass spectrometry, and for histamine by radioenzyme assay. Increased concentrations of arachidonic acid and prostaglandins D2, E2, and 6-oxo-prostaglandin F1 alpha were found maximally between 5-9 h after irradiation, preceding the phase of maximal erythema. Elevations of histamine concentration occurred 9-15 h after irradiation, preceding and coinciding with the phase of maximal erythema. At 24 h, still at the height of the erythemal response, all values had returned to near control levels. Hence increased concentrations of arachidonic acid and its products from the cyclooxygenase pathway, and of histamine, accompany the early stages up to 24 h. A causal role in production of the erythema seems likely for these substances although other mediators are almost certainly involved.

Successful treatment of severe polymorphous light eruption with azathioprine.

Two patients with severe, disabling polymorphous light eruption, who were unable to tolerate photochemotherapy and who were unresponsive to alternative recognized therapies, are described. In both cases short-term treatment with azathioprine achieved a marked clinical improvement, confirmed by testing with an irradiation monochromator. This response suggests an immunological basis for polymorphous light eruption. Patients with polymorphous light eruption vary considerably with regard to degree of photosensitivity, and while azathioprine therapy should not be considered in the majority of sufferers, we have shown that it can be very helpful in rare patients with exceptionally severe disease.

Late-onset erythropoietic protoporphyria with unusual cutaneous features.

A 68-year-old man with apparently light-exacerbated erythematous cutaneous plaques on his face and on the dorsa of his hands was found to have late-onset erythropoietic protoporphyria, diabetes mellitus, and hyperlipidemia. Extensive deposits of material that stained with periodic acid-Schiff were present in the lesional dermis. Monospecific antibody studies showed this material to be mainly type IV collagen. These findings strongly suggest that the lesions are a manifestation of erythropoietic protoporphyria. The late onset and asymptomatic unusual cutaneous lesions appear to be a new presentation of the disease.

A histological study of the evolution of solar urticaria.

The histological evolution of solar simulator-induced lesions of solar urticaria was investigated in four severely affected white patients. A series of two to 32 minimal whealing doses of radiation, each much lower than the 24-hour minimal erythema dose, was administered to separate buttock sites. Biopsy specimens were obtained from the exposed areas at five minutes and two and 24 hours later, as well as from adjacent nonexposed skin. Lesions showed a statistically significant dose-dependent increase, predominantly perivascular, in upper dermal neutrophil and eosinophil numbers at five minutes and two hours, but not at 24 hours, and at higher radiation doses in mononuclear cell numbers by 24 hours. Nonirradiated patient skin and irradiated control subject skin was not similarly affected. These changes may be associated with the pathogenesis of solar urticaria.

F-chronodispersion in patients on thalidomide.

OBJECTIVES: To describe abnormalities of F-chronodispersion in patients treated with thalidomide. METHODS: We retrospectively studies F-wave latency, persistence and F-chronodispersion in 12 patients on thalidomide treatment and compared them with a control group of another 12 patients with similar dermatological conditions who did not receive thalidomide. Furthermore, we prospectively performed longitudinal neurophysiological studies in 4 patients before and during thalidomide treatment. RESULTS: Seven of 12 patients in the retrospective study had abnormal F-chronodispersion while this was normal in all patients of the control group (P = 0.014). All other neurophysiological parameters were similar in the two groups. Two of the thalidomide patients with abnormal F-chronodispersion later developed sensory neuropathy. In all 4 patients in the prospective study though F-chronodispersion was normal before thalidomide it became markedly abnormal after exposure to this drug. CONCLUSIONS: Thalidomide may affect smaller diameter motor nerve fibres even before changes in sural sensory nerve action potentials. F-waves and F-chronodispersion should be routinely monitored in patients on thalidomide treatment.

The action spectrum for induction of chronic actinic dermatitis is similar to that for sunburn inflammation.

The action spectrum for induction of the abnormal cutaneous response at 24 h in the photosensitivity disorder chronic actinic dermatitis (CAD) was determined in 15 patients and found to be the same in shape as that for normal sunburn in fair-skinned individuals at 24 h, as determined for 47 control volunteers, although displaced in magnitude. This suggests that an endogenous chromophore(s), the same as or similar to that/those responsible for human sunburn, may be responsible for initiation of the abnormal reaction to irradiation in CAD, and that the putative antigen associated with the CAD reaction may be derived from that/those or associated molecules.