Primary Cutaneous Gamma-Delta T-Cell Lymphoma With Long-Term Indolent Clinical Course Initially Mimicking Lupus Erythematosus Profundus.

Primary Cutaneous Gamma-Delta (γδ) T-Cell Lymphoma (PCGDTCL) is a rare primary cutaneous lymphoma of aggressive nature. Only a few cases with an initially indolent course over years have been published. PCGDTCL can mimic diseases with benign behavior in their clinical and histopathological presentation, such as lupus erythematosus profundus, but also other lymphomas, for example subcutaneous panniculitis-like T-cell lymphoma. In our patient, the results of histopathological, immunofluorescence microscopy, and clinical examinations of early lesions first led to the diagnosis of lupus erythematosus profundus. Two years after this diagnosis and 6 years after the first clinical symptoms appeared, the disease progressed with erosive and ulcerating plaques and a PCGDTCL with hemophagocytic syndrome with an aggressive course was diagnosed. A distinct correlation of clinical, histopathological, immunohistochemical, and molecular-pathological examinations is needed to differentiate between the potentially malignant and benign diseases. Re-biopsies of different skin lesions in uncertain cases are strongly indicated. This case demonstrates that an indolent clinical phenotype can precede an aggressive clinical course in PCGDTCL.

Polymorphisms in the Mitochondrial Genome Are Associated With Bullous Pemphigoid in Germans.

Bullous pemphigoid (BP) is the most prevalent autoimmune skin blistering disease and is characterized by the generation of autoantibodies against the hemidesmosomal proteins BP180 (type XVII collagen) and BP230. Most intriguingly, BP is distinct from other autoimmune diseases because it predominantly affects elderly individuals above the age of 75 years, raising the question why autoantibodies and the clinical lesions of BP emerges mostly in this later stage of life, even in individuals harboring known putative BP-associated germline gene variants. The mitochondrial genome (mtDNA) is a potential candidate to provide additional insights into the BP etiology; however, the mtDNA has not been extensively explored to date. Therefore, we sequenced the whole mtDNA of German BP patients (n = 180) and age- and sex-matched healthy controls (n = 188) using next generation sequencing (NGS) technology, followed by the replication study using Sanger sequencing of an additional independent BP (n = 89) and control cohort (n = 104). While the BP and control groups showed comparable mitochondrial haplogroup distributions, the haplogroup T exhibited a tendency of higher frequency in BP patients suffering from neurodegenerative diseases (ND) compared to BP patients without ND (50%; 3 in 6 BP with haplogroup T). A total of four single nucleotide polymorphisms (SNPs) in the mtDNA, namely, m.16263T>C, m.16051A>G, and m.16162A>G in the D-loop region of the mtDNA, and m.11914G>A in the mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 4 gene (MT-ND4), were found to be significantly associated with BP based on the meta-analysis of our NGS data and the Sanger sequencing data (p = 0.0017, p = 0.0129, p = 0.0076, and p = 0.0132, respectively, Peto's test). More specifically, the three SNPs in the D-loop region were negatively, and the SNP in the MT-ND4 gene was positively associated with BP. Our study is the first to interrogate the whole mtDNA in BP patients and controls and to implicate multiple novel mtDNA variants in disease susceptibility. Studies using larger cohorts and more diverse populations are warranted to explore the functional consequences of the mtDNA variants identified in this study on immune and skin cells to understand their contributions to BP pathology.

Genetics and Omics Analysis of Autoimmune Skin Blistering Diseases.

Autoimmune blistering diseases (AIBDs) of the skin are characterized by autoantibodies against different intra-/extracellular structures within the epidermis and at the basement membrane zone (BMZ). Binding of the antibodies to their target antigen leads to inflammation at the respective binding site and degradation of these structures, resulting in the separation of the affected skin layers. Clinically, blistering, erythema and lesions of the skin and/or mucous membranes can be observed. Based on the localization of the autoantigen, AIBDs can be divided into pemphigus (intra-epidermal blistering diseases) and pemphigoid diseases (sub-epidermal blistering diseases), respectively. Although autoantigens have been extensively characterized, the underlying causes that trigger the diseases are still poorly understood. Besides the environment, genetic factors seem to play an important role in a predisposition to AIBDs. Here, we review currently known genetic and immunological mechanisms that contribute to the pathogenesis of AIBDs. Among the most commonly encountered genetic predispositions for AIBDs are the HLA gene region, and deleterious mutations of key genes for the immune system. Particularly, HLA class II genes such as the HLA-DR and HLA-DQ alleles have been shown to be prevalent in patients. This has prompted further epidemiological studies as well as unbiased Omics approaches on the transcriptome, microbiome, and proteome level to elucidate common and individual genetic risk factors as well as the molecular pathways that lead to the pathogenesis of AIBDs.

Proinflammatory Cytokine Gene Polymorphisms in Bullous Pemphigoid.

Bullous pemphigoid (BP) is a rare autoimmune skin blistering disease, characterized by the presence of autoantibodies against hemidesmosomal autoantigens. Cytokine expression is altered in BP patients, and several of these differently expressed cytokines, including IL-1α, IL-1ß, IL-8, and TNF-α, contribute to disease pathogenesis. Since genetic polymorphisms in the genes of these cytokines might be implicated in susceptibility to BP disease, we aimed at testing this implication in susceptibility to BP in an Iranian cohort. Blood samples were collected from the subjects and genomic DNA was extracted. To detect the single nucleotide polymorphisms (SNPs), IL-1α (rs1800587), IL-1ß (rs1143627, rs16944, rs1143634), IL-8 (rs4073), and TNF-α (rs1799964, rs1800630, rs1799724, and rs361525) genes were genotyped in BP patients and healthy controls as well as IL-8 (rs4073) in pemphigus vulgaris (PV) patients. Quantitative gene expression was evaluated by RT-PCR analysis. A significant difference was observed in the distribution of genotypes or alleles of IL-8 SNP between the BP patients and controls. The A-allele of IL-8 SNP is significantly more prevalent in the control individuals compared to the BP patient. To further validate this observation, we included PV patients as an additional control. Again, the A-allele of IL-8 SNP is significantly more prevalent in the PV compared to the BP patients. While we observed a trend toward significant differences regarding alleles of TNF-α rs1799724 as well as alleles of TNF-α rs1799964, this difference was, however, not evident after correction for multiple analysis. There was no significant difference in all other studied SNPs. In contrast to IL-1α, IL-1ß, and TNF-α, IL-8 gene expression levels were significantly higher in the patients than that of controls. The minor allele in IL-8 SNP might play a protective role in susceptibility to BP in Iranian patients. Although higher expression levels of IL-8 gene was found in the patients compared with healthy controls, these levels, however, suggest no association with the examined polymorphism. Moreover, further investigation revealed an elevation in gene expression between wild and polymorphic genotypes of IL-1α rs1800587 and TNF-α rs361525 in the patient group and these SNPs are therefore associated with altering the levels of gene expression.

Genome-wide association study of psoriasis in an Egyptian population.

Psoriasis is a chronic inflammatory disorder of the skin, with genetic factors reportedly involved in the disease pathogenesis. Numerous studies reported psoriasis candidate genes. However, these tend to involve mostly in the European and Asian populations. Here, we report the first genome-wide association study (GWAS) in an Egyptian population, identifying susceptibility variants for psoriasis using a two-stage case-control design. In the first discovery stage, we carried out a genome-wide association analysis using the Infinium® Global Screening Array-24 v1.0, on 253 cases and 449 control samples of Egyptian descent. In the second replication stage, 26 single-nucleotide polymorphisms (SNPs) were selected for replication in additional 321 cases and 253 controls. In concordance with the findings from previous studies on other populations, we found a genome-wide significant association between the MHC locus and the disease at rs12199223 (Pcomb  = 6.57 × 10-18 ) and rs1265181 (Pcomb  = 1.03 × 10-10 ). Additionally, we identified a novel significant association with the disease at locus, 4q32.1 (rs12650590, Pcomb  = 4.49 × 10-08 ) in the vicinity of gene GUCY1A3, and multiple suggestive associations, for example rs10832027 (Pcomb  = 7.28 × 10-06 ) and rs3770019 (Pcomb  = 1.02 × 10-05 ). This proposes the existence of important interethnic genetic differences in psoriasis susceptibility. Further studies are necessary to elucidate the downstream pathways of the new candidate loci.

Black tea dressings - a rapidly effective treatment for facial dermatitis.

Background: Facial dermatitis is a common dermatologic condition. It is usually treated with either topical corticosteroids or calcineurin inhibitors. However, the use of these drugs is limited by side effects, including skin atrophy, local immunosuppression and possible oncogenicity. Objective: The aim of the study was to evaluate the use of wet dressings with black tea for treating facial dermatitis. Methods: We performed a prospective, open, uncontrolled before-after study enrolling 22 patients with atopic or contact facial dermatitis who were treated with black tea dressings and an emollient cream over 6 days. Disease severity was assessed using the (1) Facial Eczema Area and Severity Index, (2) Visual analog scale for pruritus, (3) Investigator`s Global Assessment score, and (4) Patient's Self-Assessment score. The study was registered at www.ClinicalTrials.gov as NCT02941432. Results: A dramatic and highly significant reduction of all four disease activity scores occurred within the first 3 days of treatment and the patients continued to improve between days 3 and 6. No side effects were observed. Conclusion: Black tea dressings represent an effective treatment option for facial dermatitis. Its advantages include lack of side effects, low cost, and easy availability.

Diagnosis of Autoimmune Blistering Diseases.

Autoimmune skin blistering diseases (AIBD) are characterized by autoantibodies that are directed against structural proteins in the skin and adjacent mucous membranes. Some clinical signs are typical for a specific AIBD, however, correct diagnosis requires the detection of tissue-bound or circulating autoantibodies. The gold standard for diagnosis of AIBD is the detection of autoantibodies or complement component 3 by direct immunofluorescence (DIF) microscopy of a perilesional biopsy. Circulating antibodies can be detected via indirect immunofluorescence (IIF) microscopy of different tissue substrates including human skin, monkey esophagus, and more recently, recombinant forms of the different target antigens. Latter are also employed in various commercial ELISA systems and by immunoblotting in in-house assays available in specialized laboratories. ELISA systems are also particularly valuable for monitoring of the disease activity during the disease course which can be helpful for treatment decisions. Exact diagnosis is essential for both treatment and prognosis, since some AIBD are associated with malign tumors such as paraneoplastic pemphigus and anti-laminin 332 mucous membrane pemphigoid. This review presents clinical and immunopathological features of AIBD for the state-of the art diagnosis of these disorders.

Immunohistochemical diagnosis of mucous membrane pemphigoid.

BACKGROUND: Mucous membrane pemphigoid (MMP) is an autoimmune subepithelial blistering disease with predominant involvement of mucosal surfaces. It is usually diagnosed by direct immunofluorescence microscopy of frozen biopsies, demonstrating linear deposits of complement, IgG or IgA along the basement membrane. The aim of this study was to investigate the utility of immunohistochemistry on formalin-fixed, paraffin-embedded tissue biopsies for the diagnosis of MMP and to compare its sensitivity to that of direct immunofluorescence microscopy. METHODS: We examined 50 biopsies from 34 patients with immunologically confirmed MMP by immunohistochemistry for C3d, C4d, IgG and IgA. RESULTS: Linear deposits of C3d were detected in 46% of biopsies, and 53% of patients had at least one biopsy positive for C3d. Linear deposits of C4d were detected in 52% of biopsies and 59% of patients had at least one biopsy positive for C4d. Overall, 56% of biopsies and 68% of patients were positive by either C3d or C4d or both stainings. The sensitivity of either staining in mucosal biopsies was lower than in skin samples. Basement membrane deposits of IgG or IgA could not be detected in any biopsy. CONCLUSIONS: Our findings demonstrate that immunohistochemistry for C3d or C4d is a helpful screening procedure for cases of suspected MMP where frozen tissue is not readily available. Negative findings, however, do not exclude a possible diagnosis of MMP and should prompt an additional biopsy for direct immunofluorescence studies. Immunohistochemical detection of IgG or IgA cannot yet be used for the diagnosis of MMP.

Calcitriol Treatment Ameliorates Inflammation and Blistering in Mouse Models of Epidermolysis Bullosa Acquisita.

A link between hypovitaminosis D and development of autoimmune bullous disorders has been suggested recently, but this association has not been elaborated experimentally. Here, the role of vitamin D was investigated in epidermolysis bullosa acquisita (EBA), an anti-type VII collagen autoantibody-induced blistering skin disease. Oral administration of the hormonally active vitamin D metabolite calcitriol ameliorated clinical disease severity and dermal neutrophil infiltration in both an antibody transfer- and immunization-induced EBA mouse model. Mechanistically, calcitriol hindered immune effector cell activation as evidenced by increased L-selectin expression on Gr-1+ cells in calcitriol-treated mice with antibody transfer-induced EBA, as well as suppressed in vitro immune complex-induced reactive oxygen species production in calcitriol-treated murine neutrophils. Additionally, calcitriol administration was associated with an increase of regulatory T (CD4+FoxP3+) and B (CD19+IL10+) cells as well as reduction of pro-inflammatory T helper 17 (CD4+IL-17+) cells in mice with immunization-induced EBA. In line, levels of circulating anti-type VII collagen autoantibodies were lower in mice that received calcitriol compared to solvent-treated animals. Together with the observed state of hypovitaminosis D in most cases of an analyzed EBA patient cohort, the results of this study support the use of vitamin D derivatives or analogs for patients with EBA and related diseases.

Regulatory T Cells Suppress Inflammation and Blistering in Pemphigoid Diseases.

Regulatory T cells (Tregs) are well known for their modulatory functions in adaptive immunity. Through regulation of T cell functions, Tregs have also been demonstrated to indirectly curb myeloid cell-driven inflammation. However, direct effects of Tregs on myeloid cell functions are insufficiently characterized, especially in the context of myeloid cell-mediated diseases, such as pemphigoid diseases (PDs). PDs are caused by autoantibodies targeting structural proteins of the skin. Autoantibody binding triggers myeloid cell activation through specific activation of Fc gamma receptors, leading to skin inflammation and subepidermal blistering. Here, we used mouse models to address the potential contribution of Tregs to PD pathogenesis in vivo. Depletion of Tregs induced excessive inflammation and blistering both clinically and histologically in two different PD mouse models. Of note, in the skin of Treg-depleted mice with PD, we detected increased expression of different cytokines, including Th2-specific IL-4, IL-10, and IL-13 as well as pro-inflammatory Th1 cytokine IFN-γ and the T cell chemoattractant CXCL-9. We next aimed to determine whether Tregs alter the migratory behavior of myeloid cells, dampen immune complex (IC)-induced myeloid cell activation, or both. In vitro experiments demonstrated that co-incubation of IC-activated myeloid cells with Tregs had no impact on the release of reactive oxygen species (ROS) but downregulated ß2 integrin expression. Hence, Tregs mitigate PD by altering the migratory capabilities of myeloid cells rather than their release of ROS. Modulating cytokine expression by administering an excess of IL-10 or blocking IFN-γ may be used in clinical translation of these findings.

Topically Applied Hsp90 Blocker 17AAG Inhibits Autoantibody-Mediated Blister-Inducing Cutaneous Inflammation.

Cell stress-inducible Hsp90 has been recognized as key player in mediating inflammatory responses. Although its systemic blockade was successfully used to treat autoimmune diseases in preclinical models, efficacy of a topical route of Hsp90 inhibitor administration has so far not been evaluated in chronic inflammatory and autoimmune-mediated dermatoses. Here, effects of the Hsp90 blocker 17-allylamino-demethoxygeldanamycin (17AAG) applied topically to the skin were determined in experimental inflammatory epidermolysis bullosa acquisita (EBA), an anti-type VII collagen autoantibody-induced blistering skin disease. Topical 17AAG ameliorated clinical disease severity when given before or during the occurrence of skin lesions without causing cutaneous or systemic toxicity in mice with antibody transfer- and immunization-induced EBA. In both EBA models and in the setting of locally induced inflammation, topical 17AAG treatment was associated with (i) reduced neutrophilic infiltrates, (ii) decreased NF-κB activation, (iii) lowered expression of matrix metalloproteinases and Flii, and (iv) induction of anti-inflammatory Hsp70 in the skin. Our results suggest that topical delivery of Hsp90 antagonists, offering the benefit of a reduced risk of systemic adverse effects of Hsp90 inhibition, may be useful for the control of EBA and possibly other related inflammatory skin disorders.

T cells mediate autoantibody-induced cutaneous inflammation and blistering in epidermolysis bullosa acquisita.

T cells are key players in autoimmune diseases by supporting the production of autoantibodies. However, their contribution to the effector phase of antibody-mediated autoimmune dermatoses, i.e., tissue injury and inflammation of the skin, has not been investigated. In this paper, we demonstrate that T cells amplify the development of autoantibody-induced tissue injury in a prototypical, organ-specific autoimmune disease, namely epidermolysis bullosa acquisita (EBA) - characterized and caused by autoantibodies targeting type VII collagen. Specifically, we show that immune complex (IC)-induced inflammation depends on the presence of T cells - a process facilitated by T cell receptor (TCR)γδ and NKT cells. Because tissue damage in IC-induced inflammation is neutrophil-dependent, we further analyze the interplay between T cells and neutrophils in an experimental model of EBA. We demonstrate that T cells not only enhance neutrophil recruitment into the site of inflammation but also interact with neutrophils in lymphatic organs. Collectively, this study shows that T cells amplify the effector phase of antibody-induced tissue inflammation.

Discovering potential drug-targets for personalized treatment of autoimmune disorders - what we learn from epidermolysis bullosa acquisita.

INTRODUCTION: Epidermolysis bullosa acquisita (EBA) is a chronic autoimmune bullous dermatosis (AIBD). Treatment of EBA is challenging and mostly relies on systemic immunosuppression. During the last decade, intensive research led to the identification of new potential therapeutic targets that interfere in different phases of disease progression. Therapeutic interventions acting upon these candidate drug targets in animal models of EBA, such as cytokine-modulating biologics and small molecules, have validated them as potential new therapeutic strategies for EBA patients. AREAS COVERED: In this paper, we review the current treatments for EBA, describe the pathogenesis of the disease, and finally specify new drug candidates for the development of a more specific therapy with minimized side-effects for EBA and potentially other autoimmune diseases. EXPERT OPINION: We currently understand EBA as a disease that evolves from the interplay of many different signaling pathways. These signaling pathways, which are described in this review, provide new targets for EBA treatment. The ultimate goal of this research field is the development of specific, pathogenesis-based therapeutic strategies. Through identification of up- or downregulated pathways that dominate disease progression in individual patients, we expect therapy in EBA to become more and more precise and move towards a patient-based therapy.

Dissecting genetics of cutaneous miRNA in a mouse model of an autoimmune blistering disease.

BACKGROUND: MicroRNAs (miRNAs) are small endogenous non-coding RNAs that control genes at post-transcriptional level. They are essential for development and tissue differentiation, and such altered miRNA expression patterns are linked to the pathogenesis of inflammation and cancer. There is evidence that miRNA expression is genetically controlled similar to the transcription of protein-coding genes and previous studies identified quantitative trait loci (QTL) for miRNA expression in the liver. So far, little attention has been paid to miRNA expression in the skin. Moreover, epistatic control of miRNA expression remains unknown. In this study, we characterize genetic regulation of cutaneous miRNA and their correlation with skin inflammation using a previously established murine autoimmune-prone advanced intercross line. RESULTS: We identified in silico 42 eQTL controlling the expression of 38 cutaneous miRNAs and furthermore found two chromosomal hot-spots on chromosomes 2 and 8 that control the expression of multiple miRNAs. Moreover, for 8 miRNAs an interacting effect from pairs of SNPs was observed. Combining the constraints on genes from the statistical interaction of their loci and further using curated protein interaction networks, the number of candidate genes for association of miRNAs was reduced to a set of several genes. A cluster analysis identified miR-379 and miR-223 to be associated with EBA severity/onset, where miR-379 was observed to be associated to loci on chromosome 6. CONCLUSION: The murine advanced intercross line allowed us to identify the genetic loci regulating multiple miRNA in skin. The recurrence of trans-eQTL and epistasis suggest that cutaneous miRNAs are regulated by yet an unexplored complex gene networks. Further, using co-expression analysis of miRNA expression levels we showed that multiple miRNA contribute to multiple pathways that might be involved in pathogenesis of autoimmune skin blistering disease. Specifically, we provide evidence that miRNA such as miR-223 and miR-379 may play critical role in disease progression and severity.

Dimethylfumarate Impairs Neutrophil Functions.

Host defense against pathogens relies on neutrophil activation. Inadequate neutrophil activation is often associated with chronic inflammatory diseases. Neutrophils also constitute a significant portion of infiltrating cells in chronic inflammatory diseases, for example, psoriasis and multiple sclerosis. Fumarates improve the latter diseases, which so far has been attributed to the effects on lymphocytes and dendritic cells. Here, we focused on the effects of dimethylfumarate (DMF) on neutrophils. In vitro, DMF inhibited neutrophil activation, including changes in surface marker expression, reactive oxygen species production, formation of neutrophil extracellular traps, and migration. Phagocytic ability and autoantibody-induced, neutrophil-dependent tissue injury ex vivo was also impaired by DMF. Regarding the mode of action, DMF modulates-in a stimulus-dependent manner-neutrophil activation using the phosphoinositide 3-kinase/Akt-p38 mitogen-activated protein kinase and extracellular signal-regulated kinase 1/2 pathways. For in vivo validation, mouse models of epidermolysis bullosa acquisita, an organ-specific autoimmune disease caused by autoantibodies to type VII collagen, were employed. In the presence of DMF, blistering induced by injection of anti-type VII collagen antibodies into mice was significantly impaired. DMF treatment of mice with clinically already-manifested epidermolysis bullosa acquisita led to disease improvement. Collectively, we demonstrate a profound inhibitory activity of DMF on neutrophil functions. These findings encourage wider use of DMF in patients with neutrophil-mediated diseases.