Unique herpetiform bullous dermatosis with IgG antibodies to desmocollins 1/3 and LAD-1

Significance of anti-desmocollin autoantibodies in pemphigus

The major autoantigens for pemphigus are desmogleins (Dsgs), cell-cell adhesive structure proteins, one of the desmosomal cadherins. Recent progress in molecular biology has revealed that IgG autoantibodies of classical pemphigus react with Dsg1 or Dsg3. Desmocollins (Dscs) also belong to the cadherin supergene family that provides structure to the desmosomes and play an important role in cell-to-cell adhesion. In addition to the presence of four desmosomal Dsg isoforms, i.e. Dsg1-4, Dsc1, 2 and 3, all of which are derived from different genes, Dsc1 has been previously identified as the target antigen of IgA autoantibodies in the subcorneal pustular dermatosis (SPD)-type of intercellular IgA dermatosis. In addition to the IgA anti-Dsc1 autoantiboides, the presence of IgG anti-Dsc autoantibodies is described in patients of some autoimmune bullous diseases. In particular, the current pemphigus detecting autoantibodies to Dscs has shown a tendency in atypical variants of pemphigus. Therefore, autoantibodies against Dscs alone may cause detachment of cell-cell adhesion in the epidermis in some pemphigus. However, except for the findings of a few in vitro and in vivo studies, there is currently no clear evidence for the pathogenicity of anti-Dsc autoantibodies in pemphigus, whereas significance of anti-Dsg autoantibodies is well established. This article describes the structure and function of the Dscs, and explores the evidence regarding the pathogenic role of anti-Dsc autoantibodies in pemphigus.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

Anti-Desmocollin Autoantibodies in Autoimmune Blistering Diseases

The presence of anti-desmocollin (Dsc) antibodies is rarely described in autoimmune blistering diseases patients. Moreover, several clinical phenotypes of pemphigus may be associated with these antibodies. In this review we analyze clinicopathological, immunologic and outcome features of anti-Dsc autoimmune blistering diseases patients, to improve their diagnosis and management. We conducted a systematic search of PubMed and Embase (1990-present) for studies reporting cases of autoimmune blistering diseases with anti-Dsc antibodies. We classified the selected patients as patients with exclusively anti-Dsc autoantibodies, and patients with anti-Dsc and other autoantibodies. Of 93 cases with anti-Dsc autoantibodies included, 38 (41%) had exclusively these antibodies. Only 18% of patients presented with the typical clinicopathological phenotype of pemphigus vulgaris or pemphigus foliaceous. Mucosal involvement was seen in approximately half of the patients. Up to 18% of cases were associated with neoplasms. Acantholysis was described in 54% of cases with histopathological information. Treatments and outcomes vary in the different clinical phenotypes. The presence of anti-Dsc antibodies must be suspected mainly in those patients with either atypical pemphigus, in special with clinical pustules, or in cases showing intraepithelial or dermal neutrophilic/eosinophilic infiltrate on histological examination and dual pattern by direct immunofluorescence examination.

Herpetiform pemphigus with characteristic transmission electron microscopic findings of various-sized ballooning vacuoles in keratinocytes without acantholysis

We report a unique case of a Japanese woman with herpetiform pemphigus (HP) who had IgG autoantibodies reactive with nondesmosomal sites of keratinocytes and presented characteristic transmission electron microscopic (TEM) findings of various-sized vacuoles in keratinocytes without acantholysis. The patient presented with pruritic annular oedematous erythemas with small blisters lining the margins on the trunk and extremities. Histopathological examinations showed intraepidermal blisters with prominent infiltrations of eosinophils. Direct and indirect immunofluorescence tests revealed the presence of in vivo bound and circulating IgG autoantibodies to the keratinocyte cell surfaces. However, enzyme-linked immunosorbent assays for desmoglein (Dsg) 1, Dsg3 and desmocollins 1-3 showed negative results. Immunoblotting using the full-length human Dsg1 recombinant protein showed a positive band. TEM examination showed various-sized vacuoles squashing the nuclei in many keratinocytes, resulting in rupture of the cells. Immunoelectron microscopic examination revealed IgG deposition over the entire keratinocyte cell surfaces, which spared the desmosomes. IgG antibodies were also present on the inside walls of the vacuoles around the nuclei of keratinocytes and on the cell surfaces of infiltrating eosinophils. This patient also had marked eosinophilia and high levels of thymus and activation-regulated chemokine and interleukin-5 in the serum. These results indicated a novel autoantigen on the nondesmosomal keratinocyte cell surfaces and the pathogenesis of bullous spongiotic change with inflammation in HP.

Case of shift from linear immunoglobulin A bullous dermatosis to pemphigus herpetiformis for a short period of time

Pemphigus herpetiformis (PH) is a rare variant of pemphigus characterized by erythemas and vesicles, tending to present with annular-shaped lesions. Immunologically, immunoglobulin (Ig)G deposition at the keratinocyte cell surfaces is observed. Linear IgA bullous dermatosis (LABD) is a rare subepidermal blistering disease with linear IgA deposits at the epidermal basement membrane zone (BMZ). The annular-shaped skin lesions in PH mimic clinical manifestation of other autoimmune bullous diseases, including LABD, although PH and LABD have different immunological and histopathological features. Herein, we report the first case of a shift from LABD to PH. A 70-year-old Japanese man presented annular erythemas surrounded by vesicles on the trunk and extremities. Histopathological examination revealed subepidermal bullae and eosinophilic spongiosis. Direct immunofluorescence demonstrated linear IgA deposits at the epidermal BMZ. Immunoblot analyses of normal human epidermal and dermal extracts, supernatant of HaCaT cells, recombinant proteins of BP180 NC16a and C-terminal domains, and purified laminin-332 showed no reactivity for either IgG or IgA. IgG chemiluminescent enzyme immunoassays for desmogleins 1 and 3, and BP180 were all negative. These findings led to the diagnosis of sole LABD. Although oral prednisolone temporarily improved the skin lesions, annular erythema without vesicles remained. A new skin biopsy revealed subcorneal pustules with eosinophils, but no subepidermal bullae. Direct immunofluorescence revealed IgG and C3 deposition at the keratinocyte cell surfaces. IgG enzyme-linked immunosorbent assay for mammalian desmocollins 1-3 revealed desmocollin 1 reactivity. Based on these findings, we made a diagnosis of sole PH.

A Case of Pemphigus Herpetiformis with Only Immunoglobulin G Anti-Desmocollin 3 Antibodies

Pemphigus represents a group of autoimmune blistering diseases caused by autoantibodies against desmogleins (Dsgs), a class of desmosomal cadherins. Recently, several pemphigus patients only with desmocollin (Dsc) 3-specific antibodies have been reported. Here, we report a case of pemphigus herpetiformis (PH), where only anti-Dsc3-specific antibodies but not anti-Dsg antibodies were detected. A 76-year-old woman presented with a 3-year history of blister formation. Physical examination revealed pruritic erythemas with vesicles on the trunk and legs, but no lesions of the oral mucosa. A skin biopsy specimen revealed intraepidermal blister containing neutrophils, eosinophils, and lymphocytes. Direct immunofluorescence (IF) showed immunoglobulin G (IgG) and complement 3 (C3) depositions on the keratinocyte cell surfaces. Indirect IF showed IgG anti-keratinocyte cell surface antibodies. These findings hinted at a diagnosis of pemphigus. However, repeated enzyme-linked immunosorbent assays (ELISAs) for both anti-Dsg1 and 3 antibodies proved to be negative. Immunoblotting of normal human epidermal extracts revealed Dsc antibodies, and recently established ELISAs using human Dsc1-Dsc3 recombinantly expressed in mammalian cells detected anti-Dsc3 antibodies. Based on these clinical, histopathological, and immunological findings, the patient was diagnosed as PH with only anti-Dsc3 antibodies. Treatment with corticosteroid prednisolone and steroid-sparing agent dapsone accomplished complete clinical remission of the patient.

The expanding spectrum of IgA pemphigus: a case report and review of the literature

IgA pemphigus (IGAP) is a rare, distinct variant of pemphigus, currently classified, depending upon the histological features, immunofluorescence staining pattern and autoantibody profile, into two types: subcorneal pustular dermatosis (SPD) and intraepidermal neutrophilic IgA dermatosis. In a patient with a widespread blistering disease of the skin resembling SPD-type IGAP, we demonstrate the coexistence of IgA reactivity to both epidermal (desmocollins 2 and 3) and basement membrane-associated (BP180) proteins, suggesting the coexistence of atypical IGAP and linear IgA bullous dermatosis, respectively. This case, together with 20 previous reports of atypical IGAP, underscores the limitations of current classification schemes. Therefore, we suggest reclassifying these cases under the general term 'IGAP spectrum'.