Minao Furumura

Transcription factor hierarchy in Waardenburg syndrome: regulation of MITF expression by SOX10 and PAX3

Abstract. Waardenburg syndrome (WS) is associated with neural crest-derived melanocyte deficiency caused by mutations in either one of three transcription factors: MITF, PAX3, and SOX10. However, the hierarchical relationship of these transcription factors is largely unknown. We show that SOX10 is capable of transactivating the MITF promoter 100-fold, and that this transactivation is further stimulated by PAX3. Promoter deletion and mutational analyses indicate that SOX10 can activate MITF expression through binding to a region that is evolutionarily conserved between the mouse and human MITF promoters. A SOX10 mutant that models C-terminal truncations in WS can reduce wild-type SOX10 induction of MITF, suggesting these mutations may act in a dominant-negative fashion. Our data support a model in which the hypopigmentation in WS, of which these factors have been implicated, results from a disruption in function of the central melanocyte transcription factor MITF.

Anti-desmocollin autoantibodies in nonclassical pemphigus.

Despite the established pathogenic role of anti‐desmoglein (Dsg) antibodies in classical pemphigus, the significance of autoantibodies to another desmosomal cadherin, desmocollin (Dsc) is at present unknown. No consistent immunoassay for immunoglobulin (Ig) G autoantibodies to Dscs has been developed.

Coexistence of autoimmune bullous diseases (AIBDs) and psoriasis: A series of 145 cases

BACKGROUND Many case reports have described the coexistence of autoimmune bullous diseases (AIBDs) and psoriasis. Among them, anti-laminin γ1 (p200) pemphigoid is the best known. OBJECTIVES We sought to characterize patients with AIBDs and psoriasis and to investigate common AIBDs occurring in these patients. METHODS This retrospective study included 145 patients with coexisting AIBD and psoriasis given a diagnosis from January 1, 1996, to July 31, 2013, at an academic dermatology department. Of these, 134 were consultation cases regarding AIBD diagnosis. RESULTS Ratio of male to female patients was 5.7:1. Psoriasis onset preceded AIBD onset in most patients. Mean age at AIBD onset was 65.4 years, and mean duration between psoriasis and AIBD onset was 14.6 years. Most cases had single AIBD, whereas 16 cases had combined AIBDs. Bullous pemphigoid was the most prevalent (63.4%) followed by anti-laminin γ1 pemphigoid (37.2%). LIMITATIONS Consultation cases may not have included mild AIBD cases. CONCLUSION This study confirmed the association of psoriasis and anti-laminin γ1 pemphigoid. However, because bullous pemphigoid is a much more common disease, it is seen more frequently in patients with psoriasis than anti-laminin γ1 pemphigoid.

Distinct Characteristics in Japanese Dermatitis Herpetiformis: A Review of All 91 Japanese Patients over the Last 35 Years

We reviewed all 91 Japanese dermatitis herpetiformis (DH) patients reported over the last 35 years. The male-to-female ratio was 2 : 1. The mean age at onset was 43.8, and 13 years earlier for female patients. More than half of these Japanese DH patients showed granular IgA deposition in the papillary dermis, and another one-third showed fibrillar IgA deposition. The male patients with granular IgA deposition were 10 years older than those with fibrillar deposition. Whereas patients with granular IgA deposition showed typical distribution of the skin lesions, the predilection sites of DH tended to be spared in patients with fibrillar IgA deposition. Only 3 patients had definite gluten-sensitive enteropathy. There was a statistical difference in the frequency of human leukocyte antigen (HLA)-DR9 between the granular group and controls among Japanese. No patients had HLA-DQ2 or -DQ8, which is frequently found in Caucasian DH patients. The absence of HLA-DQ2/DQ8, the inability to identify celiac disease in most cases, the predominance of fibrillar IgA, and the unusual distribution of clinical lesions in Japanese patients suggest that Japanese DH may be a subset of DH patients and have a pathogenesis which is different from that currently proposed in Caucasian DH patients.

Diagnosis of oral mucous membrane pemphigoid by means of combined serologic testing

OBJECTIVE Mucous membrane pemphigoid (MMP) is a rare autoimmune bullous disease caused by various autoantibodies. This study aimed to evaluate the diagnostic value of MMP-specific autoantibodies in patient sera. STUDY DESIGN We analyzed sera from 30 MMP-suspected patients with intractable oral mucosal lesions using a combination of indirect immunofluorescence with 1M NaCl-split skin, immunoblot analysis, and ELISAs. We also analyzed clinical features among different types of MMP. RESULTS Seventeen, 4, and 3 patients were diagnosed with anti-BP180-type MMP, anti-laminin-332-type MMP, and combined anti-BP180/anti-laminin-332-type MMP, respectively. CONCLUSIONS Our results indicated that a combination of immunologic testing for circulating autoantibodies is useful for the diagnosis of MMP.

How do keratinizing disorders and blistering disorders overlap

Inherited keratinizing disorders are caused by mutations in the genes encoding cornified cell envelope proteins, enzymes and their inhibitors, adhesion molecules, cytoskeletal proteins and others in the epidermis. These molecules are known to regulate differentiation, proliferation and cell adhesions. Intriguingly, some keratinizing disorders show blistering skin lesions, while some inherited blistering disorders show abnormal keratinization. Therefore, hereditary keratinizing and blistering diseases are closely related and show overlapping genetic backgrounds. In this review, we overviewed keratinizing and blistering disorders in terms of overlapping of the two disease groups. Gene mutations in desmosomal components cause striate keratoderma, Naxos disease, epidermolytic palmoplantar keratoderma and plakophilin deficiency, which first show skin fragility and blisters and later hyperkeratosis. Gene mutations in hemidesmosomal components cause various forms of epidermolysis bullosa, some of which show hyperkeratosis on the nails, palms and soles, in addition to blister formation. Diseases with gene mutations in calcium pump proteins are Darier disease and Hailey–Hailey disease, which show clinicopathological overlaps and develop both keratinizing and blistering skin lesions. Finally, gene mutations in epidermal keratins cause epidermolysis bullosa simplex, epidermolytic ichthyosis, superficial epidermolytic ichthyosis, epidermolytic palmoplantar keratoderma and pachyonychia congenita/focal palmoplantar keratoderma, which show thickening of the palms and soles with underlying blister formation. In general, responsible proteins for diseases developing both keratinizing and blistering conditions are adhesion molecules, calcium pump proteins and keratins, but not connexins, cornified cell envelop proteins, enzymes or inhibitors. It is still unknown how particular keratinizing diseases develop blisters and vice versa.

Anti-Alpha-2-Macroglobulin-Like-1 Autoantibodies Are Detected Frequently and May Be Pathogenic in Paraneoplastic Pemphigus

Paraneoplastic pemphigus (PNP) shows autoantibodies mainly to plakin and desmosomal cadherin family proteins. We have recently identified alpha-2-macroglobulin-like-1 (A2ML1), a broad range protease inhibitor, as a unique PNP antigen. In this study, we tested a large number of PNP sera by various methods. Forty (69.0%) of 58 PNP sera recognized A2ML1 recombinant protein expressed in COS7 cells by immunofluorescence (IF) and/or immunoprecipitation (IP)/immunoblotting (IB). IP/IB showed higher sensitivity than IF. In addition, 22 (37.9%) PNP sera reacted with A2ML1 by IB of cultured normal human keratinocytes (NHKs) under non-reducing conditions. Statistical analyses using various clinical and immunological data showed that the presence of anti-A2ML1 autoantibodies was associated with early disease onset and absence of ocular lesions. Next, to investigate the pathogenic role of anti-A2ML1 antibody, we performed additional functional studies. Addition of anti-A2ML1 polyclonal antibody to culture media decreased NHK cell adhesion examined by dissociation assay, and increased plasmin activity detected by casein zymography, suggesting that anti-A2ML1 antibody may decrease NHK cell adhesion through plasmin activation by inhibition of A2ML1. This study demonstrates that autoantibodies to A2ML1 are frequently and specifically detected and may have a pathogenic role in PNP.

Pathogenesis of epidermolysis bullosa acquisita, an autoimmune subepidermal bullous disease†‡

Autoimmune bullous diseases (ABDs) are organ‐specific autoimmune diseases, in which blisters on the skin and mucous membranes develop through binding of pathogenic autoantibodies to target antigens. There are two major ABD groups: the pemphigus group, showing autoantibodies to desmosomal components; and the subepidermal ABD group, showing autoantibodies to hemidesmosomal components in the epidermal basement membrane zone. Recent immunological, biochemical and molecular biological studies revealed many new autoantigens, including desmocollins, various plakin family proteins and integrins. A revised ABD classification includes new disease entities such as paraneoplastic pemphigus, IgA pemphigus and anti‐laminin γ1 pemphigoid. In addition to systemic corticosteroids and various immunosuppressive agents, various adjuvant therapies for ABDs have developed. Among them, intravenous immunoglobulin (IVIG) is a promising therapy, although the therapeutic mechanisms are still unknown. Various disease models for ABDs have developed, particularly for pemphigus vulgaris, bullous pemphigoid and epidermolysis bullosa acquisita (EBA), and these have provided insights into the pathogenesis of various ADBs that suggest possible new treatment strategies. However, the fundamental mechanisms in disruption of immune‐tolerance are still unknown. EBA shows autoimmunity to type VII collagen, the major component of anchoring fibrils, and EBA pathogenesis has been studied in various disease models. Previous studies suggested that, following binding of autoantibodies to type VII collagen, activation of complement, cytokine release, neutrophil migration, Fcγ receptors (FcgRs) and metalloproteinases play important roles in induction of subepidermal blisters. In this issue of the Journal of Pathology, Kasperkiewicz and colleagues reveal important roles of activating FcgRIV and inhibitory FcgRIIB in EBA pathogenesis that were recognized by conducting elegant studies using both genetic analysis and functional animal model methods. The expression equilibrium of the activating and inhibitory FcgRs can be modulated towards the inhibitory FcgRIIB by IVIG therapy, resulting in beneficial clinical effects of IVIG in EBA and other autoimmune skin‐blistering diseases. Copyright

An attempt to develop mouse model for anti-laminin γ1 pemphigoid

BACKGROUND We recently reported that the autoantibodies of anti-p200 pemphigoid sera react with laminin γ1 and renamed this entity as anti-laminin γ1 pemphigoid. However, it has not been clarified whether the anti-laminin γ1 autoantibodies, particularly those to the C-terminal integrin binding site, affect the dermoepidermal junction and cause subepidermal blisters. OBJECTIVE The aim of this study was to develop animal models for anti-laminin γ1 pemphigoid. METHODS We attempted to produce two mouse models for anti-laminin γ1 pemphigoid; (1) a passive transfer model: injection of rabbit IgG to shorter bacterial recombinant protein of the murine laminin γ1 C-terminal 107 amino acids, and (2) an active disease model: direct immunization to mice with this recombinant protein. RESULTS Immunoblotting revealed that 70% of patient sera reacted with the shorter recombinant protein of human laminin γ1 C-terminus. In the passive transfer model, rabbit IgG to the murine laminin γ1 C-terminus was deposited, without C3 deposition, at the epidermal basement membrane zone. In contrast, in the active disease model, direct immunofluorescence of mouse skin sections showed no deposition of either murine IgG or C3. Blister formation was not seen in either model both phenotypically and histopathologically. CONCLUSION In the two different mouse animal models for anti-laminin γ1 pemphigoid, although rabbit IgG to the recombinant laminin γ1 C-terminus bound to the epidermal basement membrane zone in passive transfer model, no obvious blister formation was seen. To reproduce skin lesions in mouse models for anti-laminin γ1 pemphigoid, further improvement should be needed.

Two cases of pemphigus vegetans with IgG anti-desmocollin 3 antibodies.

IMPORTANCE Pemphigus vegetans shows clinically vegetating and/or pustular skin lesions mainly on the intertriginous areas and histopathologically neutrophilic and eosinophilic pustules in the epidermis. Pemphigus vegetans shows IgG reactivity mainly with desmoglein (Dsg) 3, but also with other autoantigens, including Dsg1 and desmocollins (Dscs). OBSERVATIONS We examined antigen profiles in 2 cases of pemphigus vegetans. (1) A women in her 80s presented with typical vegetating skin lesions on the right inguinal region with typical histopathological features. Immunoblotting using normal human epidermal extracts detected IgG antibodies to Dsg1 and Dscs. Enzyme-linked immunosorbent assays (ELISAs) revealed IgG antibodies to Dsg1 but not to Dsg3. Complementary DNA (cDNA) transfection method to COS-7 cells and novel ELISAs using eukaryotic recombinant proteins of human Dsc1, Dsc2, and Dsc3 confirmed specific IgG reactivity with Dsc3. (2) A women in her 70s presented with pustular skin lesions on the left fingers with typical histopathological features. Immunoblotting and ELISAs did not detect antibodies to either Dsg1 or Dsg3. Conversely, immunoblotting detected IgG antibodies to Dscs, cDNA transfection method revealed IgG reactivity only with Dsc3, and findings from ELISAs showed that IgG reacted weakly with Dsc2 and strongly with Dsc3. CONCLUSIONS AND RELEVANCE Autoantibodies to Dscs, particularly to Dsc3, may play a pathogenic role in some cases of pemphigus vegetans.