Photoimmunology of lupus erythematosus and dermatomyositis: a speculative review

Environmental triggers of dermatomyositis: a narrative review

Dermatomyositis (DM) is an autoimmune disease that affects the skin, lungs, and muscle. Although the pathogenesis of DM is not completely understood, several environmental triggers have been linked to DM onset or flare. This article specifically examines the effects of herbal supplements, drugs, infections, ultraviolet (UV) radiation, and environmental pollutants on the onset or exacerbation of DM. Herbal supplements such as Spirulina platensis, Aphanizomenon flos-aquae, Chlorella, Echinacea, and Alfalfa have been implicated and are frequently used in health foods. Medications such as hydroxyurea, TNF-α inhibitors, immune checkpoint inhibitors (ICI), and penicillamine, as well as certain viral infections, such as parvovirus B19, coxsackie virus, polyomavirus, Epstein-Barr virus (EBV), hepatitis, influenza, and human immunodeficiency viruses (HIV) have been associated with DM onset. Bacterial infections and vaccinations have also been linked to the development of DM. Additional environmental factors, including UV radiation and air pollutants, such as silica, biological/mineral dust, and particulate air matter from vehicle and industrial emissions, may also play a role in DM pathogenesis. Overall, there is general agreement that an autoimmune attack of the skin, muscle, and lungs in DM can be triggered by various environmental factors and warrants further investigation.

In silico Analyses of Skin and Peripheral Blood Transcriptional Data in Cutaneous Lupus Reveals CCR2-A Novel Potential Therapeutic Target

Cutaneous lesions feature prominently in lupus erythematosus (LE). Yet lupus and its cutaneous manifestations exhibit extraordinary clinical heterogeneity, making it imperative to stratify patients with varying organ involvement based on molecular criteria that may be of clinical value. We conducted several in silico bioinformatics-based analyses integrating chronic cutaneous lupus erythematosus (CCLE)-skin and blood expression profiles to provide novel insights into disease mechanisms and potential future therapy. In addition to substantiating well-known prominent apoptosis and interferon related response in both tissue environments, the overrepresentation of GO categories in the datasets, in the context of existing literature, led us to model a “disease road-map” demonstrating a coordinated orchestration of the autoimmune response in CCLE reflected in three phases: (1) initiation, (2) amplification, and (3) target damage in skin. Within this framework, we undertook in silico interactome analyses to identify significantly “over-connected” genes that are potential key functional players in the metabolic reprogramming associated with skin pathology in CCLE. Furthermore, overlapping and distinct transcriptional “hot spots” within CCLE skin and blood expression profiles mapping to specified chromosomal locations offer selected targets for identifying disease-risk genes. Lastly, we used a novel in silico approach to prioritize the receptor protein CCR2, whose expression level in CCLE tissues was validated by qPCR analysis, and suggest it as a drug target for use in future potential CCLE therapy.

The incidence of idiopathic inflammatory myopathies in the adult Slovenian population

Idiopathic Inflammatory myopathies (IIM) are rare disorders. The aim of our study was to determine the incidence of IIM in a well-defined Slovenian region. This retrospective study was conducted at the Department of Rheumatology, University Medical Centre Ljubljana, the only secondary/tertiary rheumatology center in a region with a population of 704,342 adults. We identified potential IIM cases by searching the electronic patient records for ICD-10 codes M33, M35.1, M35.8, M60, G72, G73, and J84. We included incipient IIM cases between January 2010 and December 2017, who were at the time of the diagnosis, residents of the inspected region. To avoid under-reporting due to miscoded cases, we obtained a list of the patients who had histological patterns consistent with IIM on muscle biopsy from the Institute of Pathology. The annual incidence rate for IIM was calculated. During the eight-year observation period, we identified 65 IIM cases (72.3% female, median (IQR) patient age 64.8 (54.8-73.2) years). The estimated annual incidence of IIM in the studied population was 11.5 (95% CI 9.0-14.6) per 10⁶ adults, in females 16.2 (95% CI 12.1-21.4), and in males 6.6 (95% CI 4.0-10.2) per 10⁶ adults. The incidence rate of IIM in Slovenia is consistent with data from the literature.

Cutaneous dermatomyositis: an updated review of treatment options and internal associations

Dermatomyositis is a specific type of inflammatory myopathy with characteristic cutaneous findings. Patients may have skin disease without clinically apparent muscle disease, but this disorder is best thought of as a systemic process. Therefore, all patients with dermatomyositis skin lesions need appropriate evaluation for muscle disease, esophageal dysfunction, cardiopulmonary disease, and potential internal malignancy. There are many therapies that have been used for patients with dermatomyositis, but most are based upon case series or expert opinion rather than meta-analyses or randomized, placebo-controlled trials. Even those therapies that have been subjected to randomized, blinded, placebo-controlled trials include a mixture of patients with idiopathic inflammatory myopathy and do not utilize a validated assessment tool for measuring cutaneous disease responses. In this review, we discuss the therapies available as well as the internal associations with dermatomyositis.

Clinical and pathological roles of Ro/SSA autoantibody system

Anti-Ro/SSA antibodies are among the most frequently detected autoantibodies against extractable nuclear antigens and have been associated with systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). Although the presence of these autoantibodies is one of the criteria for the diagnosis and classification of SS, they are also sometimes seen in other systemic autoimmune diseases. In the last few decades, the knowledge of the prevalence of anti-Ro/SSA antibodies in various autoimmune diseases and symptoms has been expanded, and the clinical importance of these antibodies is increasing. Nonetheless, the pathological role of the antibodies is still poorly understood. In this paper, we summarize the milestones of the anti-Ro/SSA autoantibody system and provide new insights into the association between the autoantibodies and the pathogenesis of autoimmune diseases.

Pathogenesis of cutaneous lupus erythematosus: common and different features in distinct subsets

The term 'cutaneous lupus erythematosus' (CLE) comprises several related autoimmune skin disorders, defined as 'specific' skin manifestations of lupus erythematosus (LE). The spectrum of clinical presentation of CLE is wide, reaching from mild erythema to disseminated scarring skin lesions. There is increasing knowledge concerning the pathogenesis of LE skin lesions and it has been shown that a complex network of cutaneous cytokines, chemokines and adhesion molecules orchestrate and promote tissue injury observed in LE skin lesions. However, a complete understanding of the diverse pathophysiological mechanisms in the different CLE subsets does not exist. Here we review the main pathological features described in CLE patients against the background of the clinical diversity of different CLE subtypes.

Spontaneous lupus-like syndrome in HLA-DQ2 transgenic mice with a mixed genetic background

To investigate the role of HLA-DQ2 in the pathogenesis of associated immune disorders, we generated transgenic mice that expressed HLA-DQ2 in the absence of endogenous murine class II molecules (AE(0)DQ2). These AE(0)DQ2 mice with a mixed genetic background spontaneously developed skin lesions on their ears, whereas control AE(0)DQ6 genotype control mice (also with a mixed genetic background) did not. The skin lesions were characterized by deep subepidermal blistering with hydropic degeneration and lymphoid infiltration in the subepidermal area as determined by histopathology. Immunofluorescence analysis revealed thick band-like granular deposition of IgG, IgM, and a thin band of IgA deposition along the basement membrane. AE(0)DQ2 mice also developed significant and progressive hematuria and proteinuria as compared with the AE(0)DQ6 mice (p < 0.05). Histopathology showed immune complex deposits in the glomeruli of AE(0)DQ2 mice. Immunofluorescence analysis showed progressive mesangial and capillary wall deposition of IgA, IgM, IgG and C1q in the kidney. With electron microscopy, the deposits showed a 'fingerprint' substructure; and tubuloreticular structures were identified within endothelial cells. Conversely, these changes were not observed in AE(0)DQ6 mice. Serum anti-double stranded (ds)DNA IgM and IgG levels were also significantly elevated among AE(0)DQ2 mice compared with AE(0)DQ6 mice (p < 0.001). In conclusion, AE(0)DQ2 mice spontaneously develop an autoimmune lupus-like syndrome and are useful model for this disease. It remains to be determined whether genetic admixture played a role in the development of this systemic lupus erythematosus-like syndrome in HLA-DQ2 transgenic mice. Lupus (2010) 19, 815-829.

Identification of type I interferon-associated inflammation in the pathogenesis of cutaneous lupus erythematosus opens up options for novel therapeutic approaches

Cutaneous lupus erythematosus (CLE) is one of the most common dermatological autoimmune disorders worldwide. Recently, several studies provided evidence for a pathogenic role of type I interferons (IFNs) in this disease. Plasmacytoid dendritic cells are major type I IFN producers in CLE skin lesions. Type I IFNs are able to induce the expression of several proinflammatory chemokines, including CXCL9 and 10, and enhance the cytotoxic capacity of infiltrating cells. Additionally, adhesion molecules and chemokine receptors, such as intercellular adhesion molecule-1, cutaneous lymphocyte antigen, E-selectin, CCR4 and CXCR3, are involved in the recruitment of potentially autoreactive lymphocytes into the skin. Here, we review the role of type I IFNs, adhesion molecules and chemokine receptors in CLE and discuss options for novel therapeutic approaches.

Management of cutaneous dermatomyositis: current therapeutic options

Dermatomyositis is an idiopathic inflammatory myopathy with characteristic cutaneous manifestations and proximal muscle weakness. Patients with this condition frequently require treatment for muscular, systemic, and cutaneous involvement; however, the cutaneous symptoms often cause significant morbidity and frustration to patients. The skin lesions of dermatomyositis often persist or recur after treatment of myositis, and there are subsets of patients who have significant cutaneous disease with little or no muscle involvement. Only anecdotal evidence is available for cutaneous treatment, and the approach to therapy is guided by disease severity and refractoriness. First-line therapy for localized disease begins with topical agents such as antipruritics and/or corticosteroids, while widespread disease often requires initial systemic therapy. Antimalarials are generally used for significant skin disease, followed by other anti-inflammatory agents, systemic corticosteroids, corticosteroid-sparing immunosuppressants and, recently, biologics and intravenous immunoglobulin. While there is a recognized absence of randomized prospective clinical trials examining the optimal monotherapy and combination treatment for the cutaneous manifestations of dermatomyositis, we have tried to provide a review of the literature and a systematic approach to dealing with these often refractory and debilitating symptoms.

Accumulation of apoptotic cells in the epidermis of patients with cutaneous lupus erythematosus after ultraviolet irradiation

OBJECTIVE

To examine whether apoptosis contributes to the pathogenesis of skin lesions in patients with cutaneous lupus erythematosus (CLE) after ultraviolet (UV) irradiation.

METHODS

In situ nick translation and TUNEL were performed to detect apoptosis in 85 skin biopsy specimens from patients with various subtypes of CLE. Specimens from normal healthy donors and patients with polymorphous light eruption were used as controls. In addition to assessment of primary lesions, provocative phototesting was carried out to investigate events occurring secondary to UV irradiation during a very early stage of lesion formation.

RESULTS

A significant increase in apoptotic nuclei was found in the upper epidermal layer of primary and UV light-induced skin lesions of CLE patients compared with controls. In tissue sections obtained from control subjects at 24 hours after a single exposure to UV light, a slight increase in the count of epidermal apoptotic nuclei was present as compared with skin tissue from CLE patients obtained under the same conditions before lesion formation. In sections obtained from controls at 72 hours after irradiation, a significant decrease in the apoptotic nuclei count was observed, consistent with a proper clearance of apoptotic cells in the period between 24 and 72 hours after irradiation. In striking contrast, the number of apoptotic nuclei increased significantly within this period in tissue sections from patients with CLE.

CONCLUSION

These data support the hypothesis that apoptotic cells accumulate in the skin of patients with CLE after UV irradiation, as a result of impaired or delayed clearance. The nonengulfed cells may undergo secondary necrosis and release proinflammatory compounds and potential autoantigens, which may contribute to the inflammatory micromilieu that leads to formation of skin lesions in this disease.

UV hardening therapy: a novel intervention in patients with photosensitive cutaneous lupus erythematosus

BACKGROUND

Patients with cutaneous lupus erythematosus (LE) and a history of disease- related photoaggravation, confirmed by phototesting, may not respond to photoprotection and/or medical intervention. Ultraviolet B-hardening therapy may improve tolerance for environmental ultraviolet radiation (UVR) in photosensitive disorders.

OBJECTIVE

We studied the effect of UVB hardening on the cutaneous manifestations of patients with LE and their tolerance for UVR.

PATIENTS AND METHODS

A retrospective study of continuous, home-based, UVB-hardening therapy in 44 patients with cutaneous LE (systemic LE: 9 patients; chronic LE: 21 patients; subacute cutaneous LE: 10 patients; cutaneous LE not specified: 4 patients) who had confirmed photosensitivity. Exposure to the UVB source was performed year-round, 3 times weekly, with increasing doses to a maximum of 10 minutes per session. Tolerance for environmental UVR was established through questionnaires, phototesting, and assessment of disease activity by physician and patient.

RESULTS

Of 44 patients, 35 were able to gradually increase their monthly UVB doses. Nine patients dropped out because of insufficient efficacy or skin irritation, or were unable to adhere to the hardening regimen. Of the 35 patients who succeeded in hardening their skin with UVB, 28 patients reported an improved tolerance for environmental UVR. This outcome was confirmed by repeat phototesting in a subgroup. In only 5 patients, an improvement of cutaneous LE symptoms was noted by either physician or patient. No serious adverse events were encountered.

LIMITATIONS

This was a retrospective study and no control group was used.

CONCLUSION

This is the first report that describes UVB hardening as a potential therapy in patients with cutaneous LE and confirmed photosensitivity. This intervention may lead to improved tolerance for environmental UVR and, in a minority of patients, even to decreased cutaneous activity of LE.

Photosensitivity in lupus erythematosus

Lupus erythematosus (LE) is an autoimmune disease which can be triggered by environmental factors such as solar irradiation. It has long been observed that especially ultraviolet (UV) exposure can induce and exacerbate skin lesions in patients with this disease. However, despite the frequency of photosensitivity in LE, the mechanisms by which UV irradiation activates autoimmune responses is only now becoming increasingly unfolded by advanced molecular and cellular biological investigations. Phototesting, according to a standardized protocol with UVA and UVB irradiation has proven to be a valid model to study photosensitivity in various subtypes of LE and to evaluate the underlying pathomechanisms of this disease. Detailed analysis of the molecular events that govern lesion formation in experimentally photoprovoced LE showed increased accumulation of apoptotic keratinocytes and impaired expression of the inducible nitric oxide synthase (iNOS). In the near future, gene expression profiling and proteomics will further increase our knowledge on the complexity of the "UV response" in LE. This review summarizes the current understanding of the clinical and molecular mechanisms that initiate photosensitivity in this disease.

Generation of novel covalent RNA-protein complexes in cells by ultraviolet B irradiation: implications for autoimmunity

OBJECTIVE

To determine whether ultraviolet B (UVB) irradiation induces novel modifications in autoantigens targeted during experimental photoinduced epidermal damage.

METHODS

To search for novel UVB-induced autoantigen modifications, lysates made from UVB-irradiated human keratinocytes or HeLa cells were immunoblotted using human autoantibodies that recognize ribonucleoprotein autoantigens. Novel autoantigen structures identified were further characterized using nucleases and RNA hybridization.

RESULTS

Human sera that recognize U1-70 kd (U1-70K) and La by immunoblotting also recognized multiple novel species when they were used to immunoblot lysates of UVB-irradiated keratinocytes or HeLa cells. These species were not present in control cells and were not observed when apoptosis was induced by Fas ligation or cytotoxic lymphocyte granule contents. Biochemical analysis using multiple assays revealed that these novel UVB-induced molecular species result from the covalent crosslinking between the U1 RNA and the hYRNA molecules with their associated proteins, including U1-70K, La, and likely components of the Sm particle.

CONCLUSION

These data demonstrate that UVB irradiation of live cells can directly induce covalent RNA-protein complexes, which are recognized by human autoantibodies. As previously described for other autoantigens, these covalent complexes of RNA and proteins may have important consequences in terms of antigen capture and processing.

Photoprotection by thalidomide in patients with chronic cutaneous and systemic lupus erythematosus: discordant effects on minimal erythema dose and sunburn cell formation

BACKGROUND

Thalidomide is an anti-inflammatory and immunomodulatory agent with proven efficacy in several refractory inflammatory skin conditions including photoexacerbated skin diseases. The effects of thalidomide on ultraviolet (UV)-induced cutaneous damage in humans have not been extensively studied. We describe the results of minimal erythema dose (MED) testing in nonlesional skin of three patients with chronic cutaneous lupus erythematosus (CCLE) before and after treatment with thalidomide.

OBJECTIVES

To determine whether thalidomide treatment provides clinical and histological evidence of photoprotection from acute UV injury.

METHODS

MED testing was performed in nonlesional skin of three patients with CCLE before and after treatment with thalidomide. Skin biopsy specimens were taken from MED sites for in situ immunochemistry.

RESULTS

In each patient, the MED to UVB irradiation was significantly higher while the patient was receiving thalidomide treatment than in the absence of thalidomide, suggesting a systemic photoprotective effect. Thalidomide treatment had no significant effect on markers of apoptosis including sunburn cell formation and terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labelling, which identifies single-strand breaks in DNA.

CONCLUSIONS

Thalidomide inhibits acute UVB erythema at 24 h after exposure, as a 100-mg daily dose of this drug for 4 weeks conveyed a sun protection factor of 1.56 to > 4.0. We conclude that inhibition of UVB-induced inflammation may, in part, explain the therapeutic benefits of this agent on photosensitive diseases.

Dermatomyositis: comparative studies of cutaneous photosensitivity in lupus erythematosus and normal subjects

PURPOSE

Cutaneous features of dermatomyositis (DM) strongly suggest that ultraviolet (UV) radiation plays an important role in the pathogenesis of the disease. However, the incidence and the nature of photosensitivity in this disorder have not been established. The aim of this study was to investigate the UVB (290-320 nm) minimal erythema dose (MED) in DM patients in comparison with those in lupus erythematosus (LE) and healthy controls.

METHODS

Non-irradiated back skin of 75 Caucasians with skin types II and III according to the Fitzpatrick classification were present in three different subject groups and tested for photomanifestation on non-irradiated suprascapular back skin with an ETG-1 Erythemtester. The first group included 19 DM patients, the second 30 patients with LE, and the third 26 healthy control volunteers. The MEDs were determined 24 h after irradiation adjusted according to skin type.

RESULTS

Nine of the 19 DM patients (47.4%) demonstrated reduced MEDs to UVB radiation. Seven DM patients (36.8%) had a history of increased cutaneous photosensitivity and four of these (21.1%) reported diseased aggravation after sun exposure. Both the DM and LE patient groups showed reduced MED to UVB radiation (P<0.05) compared with the control group (19.2%). Increased erythemal sensitivity to UVB irradiation was found more frequently in patients with systemic LE and cutaneous discoid LE, than in those with subacute cutaneous LE.

CONCLUSION

DM patients, similar to those with LE, showed a significantly reduced MED to UVB irradiation compared with healthy persons.

Photosensitivity in cutaneous lupus erythematosus: lessons from mice and men

Mouse models are similar but not identical to human diseases. However, they are important for research into the pathogenesis underlying autoimmune diseases because they allow us to evaluate similarities and differences between human diseases and mouse models. In fact, experimental models and inbred lupus-prone mice are tools that enable a better understanding of the 'photosensitivity' or 'photocytotoxicity' phenomena in relation to autoimmunity. Genetic studies of MRL/lpr mice revealed that the appearance of macroscopic lupus erythematosus (LE)-like skin lesions needs the lpr mutation plus an additional factor in an autosomal dominant fashion. The candidate is ultraviolet (UV) B light, the susceptibility to which is regulated by the genetic background. Such a genetic background is also speculated to be important in human cutaneous LE patients. The translocation of anti-SS-A/Ro on cultured keratinocytes irradiated with UVB light is quantitatively different from photocytotoxicity, and the quantitative levels are significantly higher in systemic LE and subacute cutaneous LE than in discoid LE and normal controls. This review focuses on the lessons gleaned from mouse and human models, and discusses photosensitivity in human cutaneous LE.

Immunology of cutaneous lupus erythematosus

The cause and effect between ultraviolet light and cutaneous lupus erythematosus (CLE) is clear. In LE patients indeed, photosensitivity is one of the major diagnostic criteria of the systemic form of lupus erythematosus. This strong clinical association has led to the postulate that abnormal photosensitivity participates in the pathogenesis of cutaneous lesions in LE. What is not clear is how the ultraviolet radiation (UVR) induces cutaneous lesions in susceptible individuals despite the fact that profound effects of UVR on the cellular components of the skin have been extensively studied. The whole scenario is complicated by the relationship between sunlight and the cutaneous immune system. Pronounced effects of UVR on the cutaneous immune response further complicate the understanding of photosensitivity in LE. In addition, the network of cutaneous cytokines, chemokines, and adhesion molecules has become increasingly intricate, thus contributing to the genetic substrate of each individual, and to the tremendous complexity of the pathogenesis of CLE.

Global surface ultraviolet radiation intensity may modulate the clinical and immunologic expression of autoimmune muscle disease

OBJECTIVE

To determine if geoclimatic factors may influence the nature and frequency of dermatomyositis (DM), polymyositis, and associated autoantibodies around the world.

METHODS

We assessed, in the first global evaluation of these conditions, the relationship between 13 geoclimatic variables that may modulate disease and the relative proportion of DM and its associated autoantibody anti-Mi-2, directed against an SNF2-superfamily helicase associated with the nucleosome remodeling and histone acetylation and deacetylation complex, in a global myositis population. Altogether, 919 consecutive patients from populations at 15 locations were studied.

RESULTS

Univariate and multivariate analyses demonstrated that of the variables evaluated, surface ultraviolet (UV) radiation intensity (irradiance) most strongly contributed to the relative proportion of DM and was strongly related to the proportion of anti-Mi-2 autoantibodies (weighted r = 0.939, P < 4 x 10(-7) and weighted r = 0.69, P = 0.02, respectively). Published ethnogeographic immunogenetic allele frequencies imply that the striking differences in the proportion of DM- and DM-specific autoantibodies observed around the world are not the result of inherent global variations in known genetic risk factors.

CONCLUSION

These data suggest that UV radiation exposure may modulate the clinical and immunologic expression of an autoimmune disease in different populations around the world.

Occupational exposures and autoimmune diseases

Autoimmune diseases are pathologic conditions defined by abnormal autoimmune responses and characterized by immune system reactivity in the form of autoantibodies and T cell responses to self-structures. Here we review the limited but growing epidemiologic and experimental literature pertaining to the association between autoimmune diseases and occupational exposure to silica, solvents, pesticides, and ultraviolet radiation. The strongest associations (i.e., relative risks of 3.0 and higher) have been documented in investigations of silica dust and rheumatoid arthritis, lupus, scleroderma and glomerulonephritis. Weaker associations are seen, however, for solvent exposures (in scleroderma, undifferentiated connective tissue disease, and multiple sclerosis) and for farming or pesticide exposures (in rheumatoid arthritis). Experimental studies suggest two different effects of these exposures: an enhanced proinflammatory (TH1) response (e.g., TNF-alpha and IL-1 cytokine production with T cell activation), and increased apoptosis of lymphocytes leading to exposure to or modification of endogenous proteins and subsequent autoantibody formation. The former is a general mechanism that may be relevant across a spectrum of autoimmune diseases, whereas the latter may be a mechanism more specific to particular diseases (e.g., ultraviolet radiation, Ro autoantibodies, and lupus). Occupational exposures are important risk factors for some autoimmune diseases, but improved exposure assessment methods and better coordination between experimental/animal models and epidemiologic studies are needed to define these risks more precisely.

Polymorphic light eruption and the HLA DRB1*0301 extended haplotype are independent risk factors for cutaneous lupus erythematosus

Recent evidence suggests that polymorphic light eruption (PLE) is an inherited photosensitivity disorder which may predispose to cutaneous lupus erythematosus (LE). In this study we examine the relative risk (RR) attributable to the presence of PLE, together with the effect of the major histocompatibility complex (MHC) in the development of cutaneous LE. Eighty-five Caucasian patients with annular subacute cutaneous LE (SCLE) and discoid LE (DLE) were recruited, together with 102 first degree relatives and 200 healthy local Caucasian controls. Symptoms suggestive of PLE were elicited in patients and relatives, and human leukocyte antigen (HLA) typing determined by PCR-SSP. Standard association analysis and family transmission disequilibrium testing (TDT) were then used to compare the HLA frequencies between groups. We found a significant (P < 0.05) association of the HL4 A*01, B*08, DRB1*0301 extended haplotype with both SCLE and DLE and also significant association of DLE with the HLA A*03, B*07, DRB1*15 haplotype, with a possible protective effect in SCLE for HLA B*44 and DRB1*04 (P=0.002 and 0.001 respectively). Association was observed between PLE and cutaneous LE (P < 0.001), but not between PLE and any HLA allele. From these figures we estimate, for the general population, that the RR of developing SCLE given the presence of (a) PLE, (b) DRB1*0301 and (c) both PLE and DRB1*0301 is 3.37, 5.45 and 12.03, respectively. For DLE, equivalent RRs are 3.11, 2.15 and 6.94. In conclusion, these data imply the involvement of both PLE and HLA DRB1*0301 in the development of SCLE and DLE. They form a basis for examining the genetic architecture of photosensitivity, some aspects of which may be common to both cutaneous LE and PLE.

Phototesting in lupus erythematosus: a 15-year experience

It has long been observed that sun exposure can induce or exacerbate skin lesions in patients with certain forms of lupus erythematosus. Despite the frequency of photosensitivity in these patients, the mechanism by which ultraviolet radiation alters the pathogenic course of this disease remains poorly understood. After development of standardized test methods, our group demonstrated in 1986 that skin lesions in patients with lupus erythematosus can be experimentally reproduced by UVA and UVB irradiation. In the following years, phototesting has received much attention as a valid model to study photosensitivity of different forms of lupus erythematosus and the pathogenetic mechanism of this disease. Further investigations have also made it possible to find genetic and immunologic factors associated with photosensitivity and have helped to identify the pathophysiologic steps involved in the induction of such skin lesions. We present phototesting results and clinical correlations of more than 400 patients with different forms of lupus erythematosus and discuss the recent advances in provocative phototesting.

Molecular genetics of cutaneous lupus erythematosus

The cutaneous forms of lupus erythematosus (LE) are true complex traits, susceptibility to which is determined by multiple factors. Good evidence exists for both genetic and environmental components to this complexity. Several different experimental techniques have found the strongest genetic associations with cutaneous LE to include sequence polymorphisms of genes encoding HLA, TNF-alpha and complement molecules, particularly in anti-Ro-positive patients. Abnormal expression of multiple other cytokines, adhesion molecules and cellular proteins (such as Ro and La) points towards a range of candidate genes that are currently being examined in cutaneous LE. Combinations of specific polymorphisms of genes encoding these immunoregulatory molecules may determine individual susceptibility to LE.

Photosensitivity in collagen vascular diseases

Clinically, photosensitivity is clearly part of both lupus erythematosus and dermatomyositis, but the prevalence of this reaction varies. Photosensitivity does not appear to be part of the disease spectrum of scleroderma or part of the clinical picture of vasculitis. Implications of photosensitivity in both lupus erythematosus and dermatomyositis are systemic. The pathogenesis of photosensitivity in lupus erythematosus and dermatomyositis is not fully understood. The presence of photosensitivity has therapeutic implications.

Spontaneous and induced apoptosis in systemic lupus erythematosus: multiple assays fail to reveal consistent abnormalities

The immunologic basis of systemic lupus erythematosus (SLE) is multifactorial and still elusive. Recent advances in the field of apoptosis have suggested new paradigms for the development of lupus autoimmunity. In the present studies we examined the possibility that individual populations of T and B cells are abnormally resistant to apoptosis or that they stand out in over- or underexpressing Fas. Fas was generally overexpressed in cells freshly isolated from SLE patients but the apoptotic response to FasL was normal. We did not find increased spontaneous ongoing apoptosis in SLE lymphocytes. Normal cleavage of PARP similarly implied that the final biochemical pathway of apoptosis is relatively intact in SLE. Finally we placed special emphasis on the response of SLE patient cells to UV irradiation, especially cells from photosensitive patients, and found no difference in Fas expression. In conclusion our results indicate that SLE patients do not suffer from a major apoptotic abnormality. The results also raise questions concerning the dynamic expression of Fas and the significance of ongoing apoptosis as a risk for autoimmune disease.

Subacute cutaneous lupus erythematosus associated with cinnarizine and thiethylperazine therapy

We report the case of a woman who developed subacute cutaneous lupus erythematosus (SCLE) after exposure to the sun while taking cinnarizine and thiethylperazine. The patient recalled that 10 years previously, a similar eruption had appeared after sunbathing, while she was taking only cinnarizine. SCLE development in this patient was probably drug related and there is some evidence that cinnarizine played an important pathogenic role.

Classification and treatment of the juvenile idiopathic inflammatory myopathies

This article reviews the current status of the classification and treatment of the juvenile idiopathic inflammatory myopathies. The intent of classification is to define homogeneous groups that share similar clinical features, disease courses, and responses to therapy. The classification scheme proposed includes clinicopathologic subsets, serologic subjects based on the presence of myositis-specific and myositis-associated autoantibodies, and environmental triggers of myositis. Juvenile dermatomyositis is the most common and widely recognized of these disorders. The second part reviews the history of treatment of juvenile dermatomyositis and discusses agents to consider for patients with refractory disease, unacceptable steroid toxicity, or poor prognostic factors.

Phototesting and photoprotection in LE

Photosensitivity and induction of skin lesions following UV radiation is a common problem of patients with cutaneous and systemic forms of lupus erythematosus. The detrimental effect of UV radiation to patients with lupus erythematosus was already recognized in the last century. Skin lesions can now be provoked under standardized conditions allowing the diagnosis and classification of patients with photosensitive disorders. The aim of this review is to give an overview on the history, test procedure and test results in patients with lupus erythematosus.

Animal models of cutaneous lupus erythematosus and lupus erythematosus photosensitivity

Over the past decade, the most exciting and important finding in SLE-prone mice is the discovery of Fas/Fas ligand systems in the pathogenesis of autoimmune phenomena. A human model for murine lpr/gld disease has also been reported recently. Furthermore, as shown in Table 2, studies on Ig variable region genes, TCR genes and MHC class II genes have given us much information concerning human and murine SLE. With respect to cytokines, IL-2 deficiency and the key role of IL-6 have been found in SLE-prone mouse strains, and Th2 cytokine production has been demonstrated to play a more pathogenic role than Th1 cytokine production in human and murine SLE except for MRL/pr mice. TGF is also very intriguing because TGF-beta knockout mice show SLE-like autoantibodies and Sjögren syndrome-like lymphoproliferation. Apart from these basic scientific investigations, there are also many promising and practical therapeutic approaches. In particular, treatments with anti-CD4 antibody and murine CTLA4Ig which bound B7 and blocked binding of CD28 to B7 are outstanding. However, it remains obscure whether such new approaches are effective for the skin lesions of SLE-prone mice, although some immunosuppressive agents such as FK506, cyclosporin and Chinese herbal medicines have been evaluated to determine their selective effects on the skin lesions of MRL/lpr mice. Needless to say, mouse models are not identical, but similar, to human diseases. However, they are important in the search for the underlying pathogenesis of autoimmune diseases on the basis of careful evaluation of the similarities and differences between human diseases and these models. If such studies are steadily performed, then inbred or experimental models will become more promising tools for the investigation of cutaneous lupus erythematosus.