[Ultraviolet radiation in the pathogenesis of lupus erythematosus]. / UV-induzierte Pathogenese des Lupus erythematodes.

Photosensitivity represents an increased inflammatory reaction to sunlight, which can be observed particularly in the autoimmune disease lupus erythematosus. Cutaneous lupus erythematosus (CLE) can be provoked by ultraviolet (UV) radiation and can cause both acute, nonscarring and chronic, scarring skin changes. In systemic lupus erythematosus, on the other hand, provocation by UV radiation can lead to flare or progression of systemic involvement. The etiology of lupus erythematosus is multifactorial and includes genetic, epigenetic and immunologic mechanisms. In this review, we address the effect of UV radiation on healthy skin and photosensitive skin using the example of lupus erythematosus. We describe possible mechanisms of UV-triggered immune responses that could offer therapeutic approaches. Currently, photosensitivity can only be prevented by avoiding UV exposure itself. Therefore, it is important to better understand the underlying mechanisms in order to develop strategies to counteract the deleterious effects of photosensitivity.

Gain-of-function human UNC93B1 variants cause systemic lupus erythematosus and chilblain lupus.

UNC93B1 is a transmembrane domain protein mediating the signaling of endosomal Toll-like receptors (TLRs). We report five families harboring rare missense substitutions (I317M, G325C, L330R, R466S, and R525P) in UNC93B1 causing systemic lupus erythematosus (SLE) or chilblain lupus (CBL) as either autosomal dominant or autosomal recessive traits. As for a D34A mutation causing murine lupus, we recorded a gain of TLR7 and, to a lesser extent, TLR8 activity with the I317M (in vitro) and G325C (in vitro and ex vivo) variants in the context of SLE. Contrastingly, in three families segregating CBL, the L330R, R466S, and R525P variants were isomorphic with respect to TLR7 activity in vitro and, for R525P, ex vivo. Rather, these variants demonstrated a gain of TLR8 activity. We observed enhanced interaction of the G325C, L330R, and R466S variants with TLR8, but not the R525P substitution, indicating different disease mechanisms. Overall, these observations suggest that UNC93B1 mutations cause monogenic SLE or CBL due to differentially enhanced TLR7 and TLR8 signaling.

[Paraneoplastic subacute cutaneous lupus erythematosus]. / Paraneoplastischer subakut kutaner Lupus erythematodes.

The genesis of subacute cutaneous lupus erythematosus (SCLE) is multifactorial and includes idiopathic, drug-related and paraneoplastic etiologies. This article reports the case of a 70-year-old female patient with paraneoplastic SCLE in whom a lung adenocarcinoma was detected during the extended examination. A paraneoplastic SCLE should be considered when a patient with SCLE presents with lesions in regions of the skin not exposed to sunlight and beginning B symptoms.

Diffuse Cutaneous Mastocytosis: A Current Understanding of a Rare Disease.

Mastocytosis is a heterogeneous disease characterized by the expansion and accumulation of neoplastic mast cells in various tissues. Diffuse cutaneous mastocytosis (DCM) is a rare and most severe form of cutaneous mastocytosis, which typically occurs in childhood. There have been reports of a familial DCM with specific gene mutations, indicating both sporadic and hereditary factors involved in its pathogenesis. DCM is associated with severe MC mediator-related symptoms and an increased risk of anaphylaxis. The diagnosis is based on the appearance of skin lesions, which typically show generalized thickening, erythroderma, blistering dermographism, and a positive Darier's sign. Recognition, particularly in infants, is challenging due to DCMs resemblance to other bullous skin disorders. Therefore, in unclear cases, a skin biopsy is crucial. Treatment focuses on symptom management, mainly including antihistamines and mast cell stabilizers. In extremely severe cases, systemic steroids, tyrosine kinase inhibitors, phototherapy, or omalizumab may be considered. Patients should be equipped with an adrenaline autoinjector. Herein, we conducted a comprehensive review of literature data on DCM since 1962, which could help to better understand both the management and prognosis of DCM, which depends on the severity of skin lesions, intensity of mediator-related symptoms, presence of anaphylaxis, and treatment response.

Comparison of patients with isolated cutaneous lupus erythematosus versus systemic lupus erythematosus with cutaneous lupus erythematosus as the sole clinical feature: A monocentric study of 149 patients.

BACKGROUND: Cutaneous lupus erythematosus (CLE) may present as an isolated entity or be classified as Systemic lupus erythematosus (SLE) by the presence of laboratory abnormalities, including cytopenia, low complement levels, and/or autoantibodies (CLE with laboratory SLE). OBJECTIVE: To compare isolated CLE and CLE with laboratory SLE and to validate an existing 3-item score with age < 25 years (1 point), phototypes V to VI (1 point), antinuclear antibodies ≥ 1:320 (5 points) to predict the risk of progression from CLE to severe SLE (sSLE). METHODS: Monocentric cohort study including consecutive patients with CLE. CLE with laboratory SLE was defined by 2019 American College of Rheumatology/European League Against Rheumatism classification criteria for SLE score of ≥10 points at baseline with CLE as the sole clinical feature. RESULTS: Of the 149 patients with CLE, 20 had CLE with laboratory SLE. The median follow-up duration was 11.3 years (IQR: 5.1-20.5). Ten patients (7%) had sSLE developed. In survival analysis, the risk of progression to sSLE was higher among CLE with laboratory SLE (hazard ratio = 6.69; 95% CI: 1.93-23.14, P < .001) compared to isolated CLE. In both groups, none of the patients with a risk score ≤ 2 had sSLE developed. LIMITATIONS: Monocentric study with a limited number of patients. CONCLUSIONS: CLE with laboratory patients with SLE have a higher risk of progression to sSLE than isolated CLE.

Lupus dermal fibroblasts are proinflammatory and exhibit a profibrotic phenotype in scarring skin disease.

Fibroblasts are stromal cells known to regulate local immune responses important for wound healing and scar formation; however, the cellular mechanisms driving damage and scarring in patients with cutaneous lupus erythematosus (CLE) remain poorly understood. Dermal fibroblasts in patients with systemic lupus erythematosus (SLE) experience increased cytokine signaling in vivo, but the effect of inflammatory mediators on fibroblast responses in nonscarring versus scarring CLE subtypes is unclear. Here, we examined responses to cytokines in dermal fibroblasts from nonlesional skin of 22 patients with SLE and CLE and 34 individuals acting as healthy controls. Notably, inflammatory cytokine responses were exaggerated in SLE fibroblasts compared with those from individuals acting as healthy controls. In lesional CLE biopsies, these same inflammatory profiles were reflected in single-cell RNA-Seq of SFRP2+ and inflammatory fibroblast subsets, and TGF-ß was identified as a critical upstream regulator for inflammatory fibroblasts in scarring discoid lupus lesions. In vitro cytokine stimulation of nonlesional fibroblasts from patients who scar from CLE identified an upregulation of collagens, particularly in response to TGF-ß, whereas inflammatory pathways were more prominent in nonscarring patients. Our study revealed that SLE fibroblasts are poised to hyperrespond to inflammation, with differential responses among patients with scarring versus nonscarring disease, providing a potential skin-specific target for mitigating damage.

Blaschkoid melanotic cutaneous lupus erythematosus with "melanocytic nests".

Melanotic cutaneous lupus erythematosus (LE) is a newly described clinical variant of chronic cutaneous LE, presenting with localized or diffuse brownish or grayish macular and reticulated pigmentation in the absence of erythema, scaling, atrophy, scarring, or telangiectasia. The diagnosis is based upon histopathology, which demonstrates the characteristic features of LE with an interface vacuolar dermatitis with melanophages, and a superficial and deep, perivascular and periadnexal lymphocytic infiltrate with mucin deposition. Herein, we describe a case of a 61-year-old White male presenting with melanotic cutaneous LE with a blaschkoid distribution on his face in which the histopathological phenomenon of "true melanocytic nests" in the setting of a lichenoid pattern was seen. We want to highlight how nests of cellular aggregates at the dermoepidermal junction labeling with melanocytic markers may occur in the setting of an interface tissue reaction. This benign reactional pattern may mimic atypical melanocytic proliferations, especially on sun-damaged skin. Clinicopathological correlation and careful microscopic examination using a panel of multiple melanocytic markers is crucial for making an accurate final diagnosis. All the cases of melanotic cutaneous LE reported in the literature are also reviewed.

The development of litifilimab (BIIB 059) for cutaneous and systemic lupus erythematosus.

This review describes the litifilimab (BIIB 059) development program to date for systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE). Plasmacytoid dendritic cells (pDCs), major producers of type I interferons (IFN-I), play a key role in SLE pathogenesis. Litifilimab, a humanized monoclonal antibody, binds to BDCA2, a protein uniquely expressed on pDCs. The consequence of BDCA2 ligation is the inhibition of IFN-I as well as IFN-III, cytokine and chemokine production. Phase I and II LILAC trial parts A and B achieved primary end points in SLE and CLE patients, confirming the importance of pDCs and IFN-I in SLE and CLE. Litifilimab is currently being evaluated in phase III trials in both SLE and CLE.

This review discusses a new medicine in development for systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE). Known as litifilimab, it binds to a protein that is only found on a specific type of cell called a plasmacytoid dendritic cell (pDC). Although all people have pDCs, patients with SLE or CLE have large amounts of these cells in certain organs, such as their skin, kidneys and joints. Since pDCs make substances that promote inflammation and contribute to some of the manifestations of SLE and CLE, litifilimab was designed to prevent these cells from making such substances. One of the key substances made by pDCs whose synthesis is blocked by litifilimab is called interferon. The article describes how litifilimab works, discusses the studies performed to date and outlines the path forward to determine if litifilimab will ultimately be a drug that clinicians can use to treat patients with SLE or CLE.

Cutaneous Toll-like Receptor 9 Pre-Defines Hydroxychloroquine Dosage in Patients with Both Discoid and Subacute Lupus Erythematosus.

Background and Objectives: Cutaneous lupus erythematosus (CLE) presents clinically heterogeneous manifestations, partially explained by the different expression of Toll-like receptors (TLRs) type 8 and 9, located to endosomal compartments where they are poised to recognize microbial nucleic acids. This disease is empirically treated with hydroxychloroquine (HCQ), which is hallmarked with a safe and effective profile, but induces a slow and sometimes clinically insufficient therapeutic response. Currently, no biomarkers predictive of response are validated or even proposed in the scientific literature. We aimed to evaluate endosomal TLR type 7, 8 and 9 as predictive biomarkers of HCQ efficacy. Materials and Methods: We conducted a case-control study comparing CLE patients retrospectively assigned to three subgroups based on 3-6-month Cutaneous LE Disease Area and Severity Index (CLASI) reduction upon treatment with HCQ (I = <40% vs. II = 40-80% vs. III = >80%). Before HCQ, lesional skin specimens were collected in untreated CLE and through immunohistochemistry; TLR-7, -8 and -9 expression was evaluated in the epidermis and the lymphocytic infiltrate was evaluated in the dermis. Results: Sixty-six lesional skin biopsies were compared with healthy controls. CLE patients displayed lower epidermal expression of total TLR 8 and 9 as well as infiltrating TLR-8, TLR9 + lymphocytes compared to controls. High HCQ responders differed from low responders for TLR-9 positivity (high vs. low) and for the lymphocytic dermal infiltrate (high vs. low). Conclusions: TLR9 could be envisaged as a possible biomarker to predict HCQ response level and dosage in CLE patients.

Non-scarring alopecia of lupus erythematosus: A comprehensive review.

BACKGROUND: Although non-scarring alopecia (NSA) is a frequent clinical finding in patients with systemic lupus erythematosus (SLE), it has been poorly described in the literature. It is considered a nonspecific sign in the current classification of skin lesions of LE. The aim of this study was to give an updated overview of the spectrum of NSA in LE patients, with emphasis on the clinical significance thereof. METHOD: We conducted a review of the English literature using the PubMed-Medline database using the keywords "Alopecia" + "Lupus erythematosus". Publications describing LE patients with NSA were included. RESULTS: Data for 237 patients from 27 publications were analyzed. Ninety-one patients had diffuse NSA, 43 had patchy NSA, 83 had lupus hair, 3 had alopecia of dermal cutaneous LE, and 17 had alopecia of linear and annular lupus panniculitis of the scalp. Patients with diffuse/patchy NSA and lupus hair shared the following features: strong association with systemic activity of LE, subtle clinical/trichoscopic signs of inflammation, histological aspect consistent with lesions specific to cutaneous LE, high likelihood of response to SLE therapy, and absence of progression to scarring alopecia. Association with SLE was rare in patients with dermal cutaneous LE or linear and annular lupus panniculitis of the scalp, and skin-directed therapies were most often effective. One patient of each subtype progressed to scarring alopecia. DISCUSSION: Diffuse/patchy NSA and lupus hair may represent a topographic variation of a single entity specific for LE. Prospective studies are warranted to further document the clinical significance of this manifestation.

Subacute cutaneous lupus erythematosus following ribociclib therapy for metastatic breast cancer.

INTRODUCTION: Drug-induced subacute cutaneous lupus erythematosus (DI-SCLE) has been associated with drugs with different mechanisms of action, including anti-hypertensives, tumour necrosis factor-α inhibitors and even some chemotherapy medicines. In the last years, a few reports have been described in patients treated with cyclin-dependent kinase (CDK) 4/6 inhibitors, palbociclib and abemaciclib. CASE REPORT: Here, we describe a case of DI-SCLE in association with ribociclib and exemestane in a woman diagnosed with metastatic breast cancer. MANAGEMENT AND OUTCOME: Topical mometasone was prescribed for two weeks with complete resolution of lesions, also abemaciclib was substituted for ribociclib, and the patient had stable disease with no relapse of DI-SCLE. DISCUSSION: To our knowledge, this is the first report of ribociclib-induced SCLE but based on the DI-SCLE reported cases associated others CDK4/6 inhibitors, the role of this family of drugs in dermatopathology must be further investigated.

A case of reactive granulomatous dermatitis associated with neonatal lupus erythematosus.

Neonatal lupus erythematosus (NLE) is an uncommon disorder affecting approximately one out of 20 000 live births in the United States. Common manifestations of NLE include cutaneous eruptions and cardiac involvement. The typical rash of NLE most closely resembles the rash of subacute cutaneous lupus erythematosus both clinically and histopathologically. We present a case of reactive granulomatous dermatitis (RGD) associated with NLE in a 3-month-old male in whom the initial histopathology and immunohistochemistry were concerning for hematologic malignancy. RGD is a unifying term used to describe cutaneous granulomatous eruptions that occur in response to a variety of stimuli, including autoimmune connective tissue diseases. Our case demonstrates the range of histopathological findings that may be present in the setting of NLE.

German Shorthaired Pointer dogs with exfoliative cutaneous lupus erythematosus develop immune-complex membranous glomerulonephropathy.

German Shorthaired Pointer (GSHP) dogs with a UNC93B1 gene mutation develop exfoliative cutaneous lupus erythematosus (ECLE) and kidney disease resembling lupus nephritis in humans. The objective of this study was to characterize the kidney disease by light microscopy, immunofluorescence, and electron microscopy in a population of GSHP dogs with ECLE. Medical records were reviewed, and light microscopy of kidneys from 7 GSHP dogs with a previous histologic diagnosis of ECLE was performed. Immunofluorescence of fresh-frozen kidney from 1 dog and transmission electron microscopy of kidney from that dog and 2 additional dogs were performed. Five of 7 dogs had proteinuria diagnosed by urinalysis or urine protein-to-creatinine ratio. Two of 7 dogs were intermittently hypoalbuminemic, and none were azotemic. Histologic findings included early (2 dogs) to late (5 dogs) membranous glomerulonephropathy characterized by mild-to-severe glomerular capillary loop thickening and tubular proteinosis. In all 7 cases, trichrome staining revealed red granular immune deposits on the subepithelial surface of the glomerular basement membrane. Immunofluorescence revealed strong granular labeling for immunoglobulins and complement protein C3. Electron microscopy demonstrated subepithelial electron-dense immune deposits encircled by the remodeled glomerular basement membrane. These findings are diagnostic of immune-complex membranous glomerulonephropathy and are similar to class V lupus in humans. This cohort of GSHP dogs with ECLE developed immune-complex membranous glomerulonephropathy, which we hypothesize is a manifestation of systemic lupus erythematosus. GSHP dogs with ECLE should undergo clinical evaluation of renal function for early identification and treatment.

Comedogenic lupus: a rare variant of chronic cutaneous lupus erythematosus - case series.

BACKGROUND: Comedogenic lupus is an uncommon variant of cutaneous lupus, clinically characterized by the presence of comedones, papules and erythematous-infiltrated plaques, cysts and scars in photo-exposed areas, mimicking acne vulgaris and acneiform eruptions. OBJECTIVES: To report clinicopathological characteristics of patients with comedogenic lupus in a tertiary dermatology service over a 15-year period and review cases described in the literature. METHODS: Retrospective study of patients with clinical and histopathological diagnoses of comedogenic lupus between the years 2006 and 2021. The literature search was carried out in the PubMed and VHL Regional Portal databases, using the terms: "comedogenic lupus" and "acneiform lupus" in Portuguese and English. RESULTS: Five patients were diagnosed during the described period, all female, with a mean age of 56.6 years. Smoking was observed in three cases, as well as pruritus. The most affected site was the face, especially the pre-auricular, malar and chin regions. Follicular plugs, epidermal thinning and liquefaction degeneration of the basal layer were predominant histopathological findings. Hydroxychloroquine was used as the first-line treatment; however, other medications were used, such as dapsone, methotrexate, tretinoin cream, and topical corticosteroids. The literature search identified 17 cases, with a mean age of 38.9 years, 82% of which were women. Only 23% had a diagnosis of systemic lupus erythematosus. Hydroxychloroquine was the most recommended systemic medication. STUDY LIMITATIONS: Retrospective, single-center study. The literature search was carried out in two databases. CONCLUSIONS: Dermatologists should be aware of acneiform conditions with poor response to the usual treatment. Early diagnosis and treatment reduce the risk of unaesthetic scars.