Cutaneous lupus erythematosus in dogs: a comprehensive review

Pharmacology of drugs used in autoimmune dermatopathies in cats and dogs: A narrative review

Immunosuppressive drugs are the mainstay of treatment for many feline and canine autoimmune skin diseases, either as monotherapy or in combination with other drugs. Treatment with these drugs is often lifelong and may have long-term consequences on the affected animal's overall quality-of-life. Clinicians need to understand the pharmacology of immunosuppressants in planning and executing the treatment regimen for the best possible clinical outcome, as well as reducing the risk of adverse effects. This review paper will focus on the mechanism of action, pharmacokinetics and pharmacodynamics, clinical uses and adverse effects of immunosuppressive drugs used to treat autoimmune dermatoses in cats and dogs. These include glucocorticoids, ciclosporin A, azathioprine, chlorambucil, mycophenolate mofetil, oclacitinib and Bruton's tyrosine kinase inhibitors.

Canine cutaneous lupus erythematosus with prominent interdigital lesions in two greyhounds

Canine cutaneous lupus erythematosus (CCLE) is a well-described, yet uncommon, autoimmune disease which can present clinically with different variants. This case report describes the clinical and histopathological presentation, and treatment response, of CCLE affecting a novel location, the interdigital skin, in two unrelated greyhounds.

Case report: Cannabinoid therapy for discoid lupus erythematosus in a dog

Discoid lupus erythematosus (DLE) is a common autoimmune skin disease in dogs. Conventional treatments, such as corticosteroids, can be effective but often have side effects. This case report presents a successful use of cannabinoid therapy (CT) in a dog with DLE resistant to conventional treatment. A 2-year-old mixed-breed dog with a history of DLE presented with worsening lesions despite treatment with corticosteroids and other medications. Liver enzymes levels were elevated, indicating corticosteroid-induced side effects. CT with a CBD-rich full spectrum Cannabis oil was initiated. The dosage was gradually adjusted until the minimum effective dose was found. Within a few weeks of starting CT, the dog showed significant improvement in skin lesions and in liver enzymes levels. After 1 year, the dog remains clinically stable on a low dose of full-spectrum CBD-rich oil. No evidence of DLE recurrence was observed. This case suggests that CT may be a viable alternative or complementary therapy for DLE in dogs, particularly for those experiencing adverse effects from conventional treatments. Further research is warranted to confirm the efficacy and safety of CT for DLE management in dogs.

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.

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Clinical and histopathological features of rostrolateral nasal alar arteriopathy of German shepherd dogs

BACKGROUND

Dermal arteritis of the nasal philtrum (DANP) has been described in large-breed dogs.

OBJECTIVES

To characterise clinically distinct, discrete fissures of the dorsolateral nasal alae associated with severe bleeding in German shepherd dogs (GSDs).

ANIMALS

Fourteen privately owned GSDs with linear rostrolateral nasal alar fissures and a histopathological diagnosis of nasal vasculopathy.

MATERIALS AND METHODS

Retrospective analysis of medical records and histological slides.

RESULTS

Mean age of onset was 6 years. Before biopsy, episodic arteriolar bleeding was noted in 11 of the 14 (79%) dogs. Slide analysis revealed enlarged nasal arterioles with expanded vascular tunics and luminal stenosis beneath ulcers. Histopathological lesions consistent with mucocutaneous pyoderma and/or facial discoid lupus erythematosus were present in 5 of the 14 (36%) dogs. Enlarged arterioles stained blue with Alcian blue and Masson's trichrome stains, consistent with deposition of mucin and collagen, respectively. Immunohistochemical stains (neutrophil myeloperoxidase, IBA1, CD3) were performed. CD3 was negative for all dogs, whilst neutrophil myeloperoxidase and IBA1 occasionally demonstrated intramural neutrophils (3 of the 14 dogs, 21%) or histiocytes (1 of the 14 dogs, 7%) in altered vessels, respectively. All dogs underwent medical management and/or surgical excision. Treatments included tacrolimus, prednisone, ciclosporin-modified, pentoxifylline, antimicrobials and doxycycline/niacinamide. No dogs were treated with antimicrobials alone. For seven dogs with long-term follow-up, treatment response was complete in five (71%) and partial in two (29%), with six of the seven (86%) receiving immunomodulatory treatments to maintain remission.

CONCLUSION AND CLINICAL RELEVANCE

Nasal alar arteriopathy of GSDs shares histopathological changes with DANP. It has characteristic clinical and histopathological features and appears amenable to immunomodulation.

Evidence-base for the beneficial effect of nutraceuticals in canine dermatological immune-mediated inflammatory diseases - A literature review

BACKGROUND

Immune-mediated inflammatory diseases (IMIDs) are associated with an abnormal immune response, resulting in a disturbed homeostasis and chronic inflammation. Most canine dermatological IMIDs (cDIMIDs), such as allergies, autoimmune and immune-mediated diseases, require long-term treatment with immunosuppressive drugs with potential adverse effects. In general, nutraceuticals are thought to be safe. As a result, there is a tendency for the more frequent use of nutraceuticals in veterinary medicine.

OBJECTIVES

The aim of this review was to present evidence-based proof for the use of various nutraceuticals in the treatment of cDIMIDs and, where possible, to provide conclusions to guide their use in veterinary dermatological practice.

METHODS

A comprehensive literature search on common cDIMIDs and nutraceuticals was performed. Only peer-reviewed articles published in English and related to the study topic were included. A total of 64 eligible publications were classified in five categories based on study design and substantively assessed on additional criteria such as standardisation of diets and number of included animals. For final appraisal, classification of major, minor or no evidence was used whereby efficacy was based on clinical outcome measurements.

CONCLUSIONS

Minor evidence for the beneficial use of several nutraceuticals, including essential fatty acids, niacinamide and probiotics, was found for treatment of specific cDIMIDs. These nutraceuticals may improve clinical signs or reduce the required dose of concurrent medication (e.g. drug-sparing effect) in some dogs. Some nutraceuticals also may be used for long-term maintenance therapy. Despite some promising findings, major evidence for the use of nutraceuticals in cDIMIDs is lacking, warranting further research.

Effective treatment of canine chronic cutaneous lupus erythematosus variants with oclacitinib: Seven cases

BACKGROUND

The treatment of canine chronic cutaneous lupus erythematosus (CCLE) variants generally requires immunosuppression, which often results in potentially severe adverse effects. Janus kinase inhibitors, like oclacitinib, might be a valuable treatment option due to their rapid inhibition of the action of interferons known to be relevant in the pathogenesis of CCLE.

OBJECTIVES

To report the efficacy and safety of oral oclacitinib for the treatment of canine CCLE variants.

ANIMALS

Seven dogs were diagnosed with CCLE based on clinical signs and compatible histopathological findings.

MATERIALS AND METHODS

Oclacitinib was administered at the induction dosage of 0.45 mg/kg twice daily to 1.8 mg/kg once daily. The response to treatment was graded as 'good' when there was ≥50% lesion reduction, or as 'complete remission' if all active lesions had resolved. Complete blood counts were performed at variable intervals.

RESULTS

A complete remission of all lesions was obtained in the dog with exfoliative cutaneous lupus erythematosus, both dogs with mucocutaneous lupus erythematosus and three of four dogs with facial discoid lupus erythematosus (FDLE); a good response was seen in the remaining dog with FDLE. The first visible improvement of signs was seen within 2-to-3 weeks, while the time to complete remission was around 2 months. Clinical adverse effects were not seen, and haematological parameters remained within the reference range.

CONCLUSIONS AND CLINICAL RELEVANCE

Oclacitinib may be considered an effective treatment option for different variants of canine CCLE.

Comparison of three canine nose guards for reduction of ultraviolet (UVA and UVB) solar radiation

BACKGROUND

Protection from solar ultraviolet (UV) radiation is paramount for some dermatological conditions, yet there are no studies assessing UV nose guards for dogs.

OBJECTIVES

Compare the ability of three nasal guards to block solar UV radiation (UVR) from the canine nose, using two commercial products and one created by the authors.

ANIMALS

Four fabric model dogs were used in this prospective controlled trial.

MATERIALS AND METHODS

Each model had a UV dosimeter applied to the dorsal nose and anterior nasal planum. Three models had nose protectors applied: (1) a mesh hood (OutFox Field Guard, OutFox For Dogs); (2) a fabric nose shield (Nose Protector, Dog Nose Protectors); or (3) a basket muzzle with ultraviolet protection factor (UPF) 50+ fabric developed by the authors. The control had no protective device applied. All the models were placed in direct sunlight and measurements taken over nine 2 h time periods. Total cumulative UVR was analysed for each location and type of guard or control.

RESULTS

All guards provided statistically significant UV protection compared to control at all time points (p < 0.001). The basket muzzle with UPF 50+ guard was consistent in protecting the dorsal and anterior nose, blocking 94.2% and 94.3% UVR, respectively. The fabric nose protector blocked 99.2% UVR from the dorsal and 82.9% anterior. The mesh hood blocked 72.5% of UVR dorsal and 71.4% anterior.

CONCLUSIONS AND CLINICAL RELEVANCE

Two guards were superior in blocking UVR; however, the choice of UV guard in a clinical setting depends on an individual's disease location and tolerance of the device.

A Retrospective Evaluation of the Steroid-Sparing Effect of Oral Modified Ciclosporin for Treatment of Canine Pemphigus Foliaceus

The efficacy of ciclosporin as an adjuvant immunosuppressant administered with glucocorticoids (GCs) for induction of canine PF remission is unknown. This study is a retrospective review of medical records from 2015 to 2020 to evaluate the therapeutic outcomes of 11 PF dogs treated with oral modified ciclosporin and GCs. Concurrent GCs were given with ciclosporin to all PF dogs. Nine dogs (9/11) achieved complete remission (CR); five dogs received ciclosporin at a mean dose of 6.2 mg/kg/day; and four dogs received a combination of ciclosporin and ketoconazole at a mean dose of 3 mg/kg/day, respectively. Two dogs (2/11) showed only 25% or poor response, with the development of new PF lesions during treatment. The mean duration of ciclosporin therapy for nine dogs to achieve CR was 65 days (median 57 days, range 24–119 days). Slow tapering of oral GCs while continuing ciclosporin at the same dose and frequency in nine dogs with CR led to recurrence of PF lesions in four dogs, whereas, in five dogs, oral glucocorticoids were discontinued without a PF flare. Oral modified ciclosporin combined with GCs achieved CR in 9 out of 11 PF dogs during the induction phase in this study.

Using Gene Expression Analysis to Understand Complex Autoimmune Skin Disease Patients: A Series of Four Canine Cutaneous Lupus Erythematosus Cases

Cutaneous Lupus Erythematosus (CLE) is an autoimmune skin disease that occurs in almost two-thirds of people with Systemic Lupus Erythematosus (SLE) and can exist as its own entity. Despite its negative impact on the quality of life of patients, lupus pathogenesis is not fully understood. In recent years, the role of gene expression analysis has become important in understanding cellular functions and disease causation within and across species. Interestingly, dogs also develop CLE, providing a spontaneous animal model of disease. Here, we present a targeted transcriptomic analysis of skin biopsies from a case series of four dogs with complex autoimmunity with suspected CLE. We identified 92 differentially expressed genes (DEGs), including type 1 interferon, B cell, and T cell-related genes, in the four cases compared to healthy skin margin controls. Additionally, we compared our results with existing CLE datasets from humans and mice and found that humans and canines share 49 DEGs, whereas humans and mice shared only 25 DEGs in our gene set. Immunohistochemistry of IFNG and CXCL10, two of the most highly upregulated inflammatory mediators, confirmed protein-level expression and revealed immune cells as the primary source of CXCL10 in dogs with SLE, whereas keratinocytes stained strongly for CXCL10 in dogs without SLE. We propose that gene expression analysis may aid the diagnosis of complex autoimmune skin diseases and that dogs may provide important insights into CLE and SLE pathogeneses, or more broadly, skin manifestations during systemic autoimmunity.

A scoping review of autoantibodies as biomarkers for canine autoimmune disease

Background

Autoantibody biomarkers are valuable tools used to diagnose and manage autoimmune diseases in dogs. However, prior publications have raised concerns over a lack of standardization and sufficient validation for the use of biomarkers in veterinary medicine.

Objectives

Systematically compile primary research on autoantibody biomarkers for autoimmune disease in dogs, summarize their methodological features, and evaluate their quality; synthesize data supporting their use into a resource for veterinarians and researchers.

Animals

Not used.

Methods

Five indices were searched to identify studies for evaluation: PubMed, CAB Abstracts, Web of Science, Agricola, and SCOPUS. Two independent reviewers (AET and ELC) screened titles and abstracts for exclusion criteria followed by full‐text review of remaining articles. Relevant studies were classified based on study objectives (biomarker, epitope, technique). Data on study characteristics and outcomes were synthesized in independent data tables for each classification.

Results

Ninety‐two studies qualified for final analysis (n = 49 biomarker, n = 9 epitope, and n = 34 technique studies). A high degree of heterogeneity in study characteristics and outcomes reporting was observed. Opportunities to strengthen future studies could include: (1) routine use of negative controls, (2) power analyses to inform sample sizes, (3) statistical analyses when appropriate, and (4) multiple detection techniques to confirm results.

Conclusions

These findings provide a resource that will allow veterinary clinicians to efficiently evaluate the evidence supporting the use of autoantibody biomarkers, along with the varied methodological approaches used in their development.

Variants Affecting the C-Terminal Tail of UNC93B1 Are Not a Common Risk Factor for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous multifactorial disease. Upregulated TLR7 signaling is a known risk factor for SLE. Recently, it was shown that specific genetic variants in UNC93B1 affect the physiological regulation of TLR7 signaling and cause characteristic autoimmune phenotypes with monogenic autosomal recessive inheritance in mutant mice and dogs. We therefore hypothesized that homologous variants in the human UNC93B1 gene might be responsible for a fraction of human SLE patients. We analyzed 536 patients of the Swiss SLE Cohort Study for the presence of genetic variants affecting the C-terminal tail of UNC93B1. None of the investigated patients carried bi-allelic UNC93B1 variants that were likely to explain their SLE phenotypes. We conclude that genetic variants affecting the C-terminal tail of UNC93B1 are not a common risk factor for SLE. It cannot be excluded that such variants might contribute to other heritable autoimmune diseases.

Successful Treatment of Mucocutaneous Lupus Erythematosus in a Dog with Prednisolone, Mycophenolate Mofetil and Tacrolimus

A 6-year-old, intact male miniature Pinscher dog had erosive lesions on perilabial, peripenial and perianal mucocutaneous areas, which were exacerbated by ulcerations, crusts, with pain while defecating and urinating. The lesions were symmetrical, and no systemic signs were observed. Histopathological evaluation showed parakeratotic hyperkeratosis, ulceration and cell-rich lymphoplasmacytic interface dermatitis with basal keratinocyte apoptosis. Immunohistochemistry revealed strong reaction in the dermoepidermal junction against goat-canine IgG and mild-to-moderate reaction against goat-canine IgA, IgM and C3. Based on these findings, the dog was diagnosed with mucocutaneous lupus erythematosus (MCLE). Oral prednisolone 1 mg/kg twice daily, mycophenolate mofetil (MMF) 18.3 mg/kg twice daily and 0.1% tacrolimus ointment were prescribed as initial treatment. The lesions showed remarkable improvement within 4 weeks, but the dog exhibited polyuria, polydipsia and hepatomegaly with high dosage of prednisolone. Hence, the dosage of prednisolone was gradually tapered for 9 weeks and discontinued, but MMF and tacrolimus were continued. No new lesion or associated side effect was observed while reducing the MMF dose to 10 mg/kg twice daily and with continuous use of tacrolimus ointment after steroid discontinuation. In conclusion, this case report emphasizes the usefulness of MMF and tacrolimus as steroid-sparing agents in the treatment of dogs with MCLE. To the best of our knowledge, this is the first case report of MCLE that was successfully managed long-term with MMF and tacrolimus.

Increased Expression of Toll-Like Receptor 4 in Skin of Dogs with Discoid Lupus Erythematous (DLE)

Simple Summary

Discoid lupus erythematous (DLE) is a common autoimmune skin disorder of dogs. The aim of this study was to evaluate the expression of TLR4, a bacterial lipopolysaccharide sensor, in skin of dogs with DLE and in normal skin to evaluate a possible involvement of this receptor in the disease pathogenesis. Skin samples of affected dogs had a diffuse and intense expression of TLR4, both in the epidermis and in inflammatory infiltrates. The expression was higher in DLE skin compared to normal skin. The high TLR4 expression might play an important pathogenic role in the ongoing immunopathologic process.

Abstract

Discoid lupus erythematous (DLE) is a common autoimmune skin disorder of dogs where keratinocytes play a pivotal role both in the innate and adaptive immune responses. As for the innate response, pattern recognition receptors (PRR), including Toll-like receptors (TLRs), can activate macrophages and immune tissue cells allowing for transmission and transduction of signals through cytokine and chemokine release to improve host defenses. In particular, TLR4 can also recognize endogenous molecules such as heat shock proteins produced during reactions to tissue damage. The aim of this study was to evaluate the expression of TLR4, a bacterial lipopolysaccharide sensor, in the skin of dogs with DLE and in normal skin to evaluate a possible involvement of this receptor in the disease pathogenesis. Skin samples of affected dogs had a diffuse and intense expression of TLR4 in the epidermis. Also, the inflammatory infiltrates were immunolabelled. The expression was significantly higher in DLE skin compared to normal skin (**** p < 0.0001). In conclusion, dogs with DLE showed an altered expression of TLR4, which might play an important pathogenic role in the ongoing immunopathologic process, thus being considered a valuable therapeutic potential target for DLE.

Recent Insight on the Management of Lupus Erythematosus Alopecia

Lupus erythematosus (LE) is a chronic autoimmune condition with a wide spectrum of clinical presentations. Alopecias, both non-scarring and scarring, frequently occur in the context of LE and can assume several different patterns. Furthermore, alopecia occurring with LE may be considered LE-specific if LE-specific features are present on histology; otherwise, alopecia is considered non-LE-specific. Non-scarring alopecia is highly specific to systemic LE (SLE), and therefore has been regarded as a criterion for the diagnosis of SLE. Variants of cutaneous LE (CLE), including acute, subacute, and chronic forms, are also capable of causing hair loss, and chronic CLE is an important cause of primary cicatricial alopecia. Other types of hair loss not specific to LE, including telogen effluvium, alopecia areata, and anagen effluvium, may also occur in a patient with lupus. Lupus alopecia may be difficult to treat, particularly in cases that have progressed to scarring. The article summarizes the types of lupus alopecia and recent insight regarding their management. Data regarding the management of lupus alopecia are sparse and limited to case reports, and therefore, many studies including in this review report the efficacy of treatments on CLE as a broader entity. In general, for patients with non-scarring alopecia in SLE, management is aimed at controlling SLE activity with subsequent hair regrowth. Topical medications can be used to expedite recovery. Prompt treatment is crucial in the case of chronic CLE due to potential for scarring and irreversible damage. First-line therapies for CLE include topical corticosteroids and oral antimalarials, with or without oral corticosteroids as bridging therapy. Second and third-line systemic treatments for CLE include methotrexate, retinoids, dapsone, mycophenolate mofetil, and mycophenolate acid. Additional topical and systemic medications as well as physical modalities used for the treatment of lupus alopecia and CLE are discussed herein.

Transcriptional Differences between Canine Cutaneous Epitheliotropic Lymphoma and Immune-Mediated Dermatoses

Canine cutaneous epitheliotropic T-cell lymphoma (CETL) and immune-mediated T-cell predominant dermatoses (IMD) share several clinical and histopathological features, but differ substantially in prognosis. The discrimination of ambiguous cases may be challenging, as diagnostic tests are limited and may prove equivocal. This study aimed to investigate transcriptional differences between CETL and IMD, as a basis for further research on discriminating diagnostic biomarkers. We performed 100bp single-end sequencing on RNA extracted from formalin-fixed and paraffin-embedded skin biopsies from dogs with CETL and IMD, respectively. DESeq2 was used for principal component analysis (PCA) and differential gene expression analysis. Genes with significantly different expression were analyzed for enriched pathways using two different tools. The expression of selected genes and their proteins was validated by RT-qPCR and immunohistochemistry. PCA demonstrated the distinct gene expression profiles of CETL and IMD. In total, 503 genes were upregulated, while 4986 were downregulated in CETL compared to IMD. RT-qPCR confirmed the sequencing results for 5/6 selected genes tested, while the protein expression detected by immunohistochemistry was not entirely consistent. Our study revealed transcriptional differences between canine CETL and IMD, with similarities to human cutaneous lymphoma. Differentially expressed genes are potential discriminatory markers, but require further validation on larger sample collections.

Shared inflammatory and skin-specific gene signatures reveal common drivers of discoid lupus erythematosus in canines, humans and mice

Autoimmune skin diseases are complex and are thought to arise from a combination of genetics and environmental exposures, which trigger an ongoing immune response against self-antigens. Companion animals including cats and dogs are known to develop inflammatory skin conditions similar to humans and share the same environment, providing opportunities to study spontaneous disease that encompasses genetic and environmental factors with a One Health approach. A strength of comparative immunology approaches is that immune profiles may be assessed across different species to better identify shared or conserved pathways that might drive inflammation. Here, we performed a comparative study of skin from canine discoid lupus erythematosus (DLE) using NanoString nCounter technology. We compared these gene expression patterns to those of human DLE and a mouse model of cutaneous lupus. We found strong interferon signatures, with CXCL10, ISG15, and an S100 gene family member among the highest, most significant DEGs upregulated across species. Cell type analysis revealed marked T-cell and B-cell infiltration. Interestingly, canine DLE samples also recapitulated downregulated skin homeostatic genes observed in human DLE. We conclude that spontaneous DLE in dogs captures many features that are present in human disease and may serve as a more complete model for conducting further genomic and/or transcriptomic studies.

•

Canine DLE lesions express known drivers of pathogenesis including CXCL10, IFNG, FAS.

•

Enrichment of key cell types, including T, B, NK cells, is observed in canine DLE.

•

Canine, mouse and human DLE share similar proinflammatory profiles.

•

Canine DLE exhibits downregulated skin homeostatic and immune regulatory genes.

Dietary supplements in dermatology: A review of the evidence for zinc, biotin, vitamin D, nicotinamide, and Polypodium

Dietary supplements are commonly recommended by dermatologists in the treatment of skin, hair, and nail disorders. This review of oral over-the-counter supplement use in dermatology summarizes current evidence for the use of zinc, biotin, vitamin D, nicotinamide, and Polypodium in the management of common dermatologic disorders. Evidence for the safety and efficacy of these supplements is limited. Very few large-scale randomized controlled trials exist for these over-the-counter supplements, particularly biotin and Polypodium. The lack of standardized dosing and standardized outcome measures makes comparison across existing studies challenging, and the lack of adverse events reporting in the majority of studies limits analysis of supplement safety. The most promising evidence exists for the use of nicotinamide in preventing nonmelanoma skin cancers. There is some evidence for the role of vitamin D in decreasing melanoma risk and progression in some individuals and for the photoprotective role of Polypodium, although additional high-quality studies are needed to determine appropriate dosing. Current evidence is insufficient to recommend the use of biotin or zinc supplements in dermatology. Large-scale randomized controlled trials investigating safety and efficacy are needed before widespread incorporation of these oral supplements into the general practice of dermatology.

A Missense Variant Affecting the C-Terminal Tail of UNC93B1 in Dogs with Exfoliative Cutaneous Lupus Erythematosus (ECLE)

Cutaneous lupus erythematosus (CLE) in humans encompasses multiple subtypes that exhibit a wide array of skin lesions and, in some cases, are associated with the development of systemic lupus erythematosus (SLE). We investigated dogs with exfoliative cutaneous lupus erythematosus (ECLE), a dog-specific form of chronic CLE that is inherited as a monogenic autosomal recessive trait. A genome-wide association study (GWAS) with 14 cases and 29 controls confirmed a previously published result that the causative variant maps to chromosome 18. Autozygosity mapping refined the ECLE locus to a 493 kb critical interval. Filtering of whole genome sequence data from two cases against 654 controls revealed a single private protein-changing variant in this critical interval, UNC93B1:c.1438C>A or p.Pro480Thr. The homozygous mutant genotype was exclusively observed in 23 ECLE affected German Shorthaired Pointers and an ECLE affected Vizsla, but absent from 845 controls. UNC93B1 is a transmembrane protein located in the endoplasmic reticulum and endolysosomes, which is required for correct trafficking of several Toll-like receptors (TLRs). The p.Pro480Thr variant is predicted to affect the C-terminal tail of the UNC93B1 that has recently been shown to restrict TLR7 mediated autoimmunity via an interaction with syndecan binding protein (SDCBP). The functional knowledge on UNC93B1 strongly suggests that p.Pro480Thr is causing ECLE in dogs. These dogs therefore represent an interesting spontaneous model for human lupus erythematosus. Our results warrant further investigations of whether genetic variants affecting the C-terminus of UNC93B1 might be involved in specific subsets of CLE or SLE cases in humans and other species.

Treatment of exfoliative cutaneous lupus erythematosus in a German shorthaired pointer dog with mycophenolate mofetil

BACKGROUND

Immune-modulating drugs show limited therapeutic efficacy in canine exfoliative cutaneous lupus erythematosus (ECLE); over half of ECLE dogs are eventually euthanized for their lack of response to therapy.

OBJECTIVE

To describe a case of generalized ECLE in a dog in which mycophenolate mofetil (MMF) treatment achieved complete remission.

ANIMAL

A 3-year-old, male castrated German shorthaired pointer was presented with a three months history of generalized scaling, erythematous macules and plaques, follicular casts and hypotrichosis affecting the head, trunk, ventrum and medial aspects of all limbs. The dog exhibited lameness and stiff gait.

METHODS AND MATERIALS

Complete blood count, serum chemistry profile, urinalysis, serum antinuclear antibody test, histopathological examination and RT-qPCR of skin biopsies.

RESULTS

Histologically, skin biopsy specimens revealed lymphocyte-rich interface dermatitis, infundibular interface mural folliculitis and periglandular lymphocytic infiltrate. The absence of systemic signs and unremarkable laboratory tests excluded concurrent systemic lupus erythematosus. Treatment of ECLE was initiated with oral MMF (22 mg/kg, twice daily). Within three weeks of starting MMF therapy, a marked improvement in lameness and a moderate decrease in erythema and scaling was observed. After four months, erythema, scaling and follicular casts had completely resolved, and at the time of writing the dog's ECLE remains in complete remission with twice daily MMF (10 mg/kg). The lesional skin transcriptome revealed predominant T helper 1 (Th1) lymphocytic inflammatory response with strong upregulation of interferon pathway.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge, this is the first reported case of successful treatment of ECLE with MMF as a single-agent therapy.