A case of anti-p200 pemphigoid: evidence for a different pathway in neutrophil recruitment compared with bullous pemphigoid

Potential contribution of anti-p200 autoantibodies to mucosal lesions in anti-p200 pemphigoid

Anti-p200 pemphigoid is a relatively rare subepidermal autoimmune bullous disease (AIBD), which was firstly reported by Detlef Zillikens, Takashi Hashimoto and others in 1996. Skin lesions are considered as the major clinical features of this disease, with occasional involvement of mucosal lesions. The mechanism of mucosal lesions involved in anti-p200 pemphigoid is still unclear. In the present study, we aimed to analyze published data on cases and case series of anti-p200 pemphigoid with mucosal lesions and explored the potential contribution of anti-p200 autoantibodies to mucosal lesions. A total of 32 papers that comprised 52 anti-p200 pemphigoid patients with various mucosal lesions were included in this review. Oral lesions were involved in 75.0% patients, followed by genital lesions (26.9%) and ocular lesions (11.54%). Only one patient had psoriasis, 26.9% patients had multiple mucosal lesions, and 30.8% cases had comorbidity of other AIBDs, particularly anti-laminin (LM) 332-type mucous membrane pemphigoid (MMP). In comparison with anti-LM332-type MMP, anti-BP180-type MMP and epidermolysis bullosa acquisita, higher frequency of genital lesions was identified as a unique character of anti-p200 pemphigoid with mucosal lesions. These results indicated that anti-p200 autoantibodies might contribute to mucosal lesions in a pattern different from other MMP-related autoantibodies, although its pathogenetic mechanisms are still unclear.

Hypoxia in A Patient with Anti-p200 Pemphigoid under Combined Dapsone and Pantoprazole Treatment

A 70-year-old male patient was admitted to our dermatology outpatient clinic with newly developed personality changes and signs of hypoxemia. His anti-p200 Pemphigoid was treated with Dapsone for a few weeks. Due to generalized tonic-clonic seizure with a subsequent Glasgow Coma Scale of 5 points and a peripheral oxygen saturation not exceeding 88% under conditions of high-flow nasal cannula, he was intubated by the emergency team and transferred to the intensive care unit. Comprehensive tests were performed, but Dapsone-induced methemoglobinemia remained the exclusive explanation for the observed scenario, although arterial MetHb analysis showed a peak value of only 6%. The patient recovered shortly after repeated infusions of Methylene blue and Ascorbate, and cessation of Dapsone. We provide an overview of the pathophysiology, diagnostic procedures, and possible explanations for this case of Dapsone-induced methaemoglobinaemia. In conclusion, our case report provides evidence that even mild chronic methemglobinemia can induce severe clinical symptoms.

Anti-P 200 pemphigoid - The most common floor binding subepidermal autoimmune bullous disease in a tertiary care center in south India

BACKGROUND

The pemphigoid group of diseases may present clinically and immunologically in a very similar fashion. Indirect immunofluorescence microscopy with readily available salt-split human skin in a BIOCHIP™ helps to classify these conditions as those with either with roof binding or floor binding of immunoreactants. Epidermolysis bullosa acquisita, anti-laminin 332 pemphigoid and anti-p200 pemphigoid show floor binding, while in the most frequent type of pemphigoid disease, bullous pemphigoid, epidermal side staining pattern is seen on salt-split skin Aims: The aim of the study was to detect the target antigens in sub-epidermal bullous diseases.

METHODS

Forty patients with bullous pemphigoid diagnosed by lesional histopathology and direct immunofluorescence microscopy were re-evaluated by a BIOCHIP™ mosaic containing both tissue substrates and recombinant target antigens. Sera with floor pattern staining on salt-split skin were further evaluated by immunoblotting with dermal extract.

RESULTS

Five patients with floor staining had anti-p200 pemphigoid.

LIMITATIONS

We could not perform serration pattern analysis of direct immunofluorescence in our patients.

CONCLUSION

Histopathology and direct immunofluorescence microscopy cannot differentiate between various entities of pemphigoid diseases. A multivariant approach using a BIOCHIP™ mosaic including salt-split skin followed by immunoblotting with dermal extract helps to identify the target antigen.

[Anti-p200 pemphigoid]

Anti-p200 pemphigoid is a rare autoimmune blistering disease. It belongs to the group of pemphigoid diseases and was first described in 1996. The diagnostic gold standard is the combination of (1) linear deposits of immunoreactants at the dermal epidermal junction by direct immunofluorescence microscopy of a perilesional skin biopsy, (2) detection of circulating autoantibodies binding to the dermal side (blister floor) of human salt split skin by indirect immunofluorescence microscopy, and reactivity with a 200 kDa protein (p200) in extract of human dermis by immunoblotting. In 2009, laminin γ1 was described as an additional target antigen in 90% of anti-p200 pemphigoid patients. Since ex vivo and in vivo studies have shown no direct pathogenic relevance for laminin γ1 antibodies and the preadsorption of patient sera against laminin γ1 does not reduce their reactivity with p200, the molecular identity of p200 still remains to be elucidated. The clinical phenotype of the disease is heterogeneous; in most cases, however, it resembles bullous pemphigoid. Anti-p200 patients are younger and skin lesions more often appear on palms of the hands and soles of the feet than in bullous pemphigoid. Therapy consists of topical and systemic corticosteroids. In addition, the use of daspone and immunosuppressants has been reported.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

Anti-p200 pemphigoid

Anti-p200 pemphigoid is a rare subepidermal blistering skin disease. Patients' autoantibodies label the dermal side of 1 mol/L NaCl-split human skin by indirect immunofluorescence microscopy and recognize a 200-kd protein by immunoblotting of human dermal extract. Clinically, anti-p200 pemphigoid is characterized by tense blisters and vesicles, erosions, and urticarial plaques, closely resembling bullous pemphigoid and the inflammatory variant of epidermolysis bullosa acquisita. Recently, 90% of anti-p200 pemphigoid sera were shown to recognize laminin γ1. The C-terminus of laminin γ1 was identified as an immunodominant region and in its recombinant form was used by immunoblotting and enzyme-linked immunosorbent assay for the serologic diagnosis of this disease. Subsequent ex vivo and in vivo studies were, however, unable to show pathogenic activity of antilaminin γ1 antibodies. Both patients' sera and sera depleted from antilaminin γ1 antibodies induced subepidermal splitting in an ex vivo model of autoantibody-mediated leukocyte-dependent neutrophil activation. Antilaminin γ1 antibodies appear to be useful biomarkers that will further facilitate the diagnosis of anti-p200 pemphigoid. The true identity of the pathogenetically relevant autoantigen of this disease, which may either be a yet unknown isoform of laminin γ1 or even another 200-kd protein of the dermoepidermal junction, still needs to be elucidated.

[Anti-p200 pemphigoid: a spectacular response to dapsone]

BACKGROUND

Types of subepidermal autoimmune bullous dermatosis (AIBD) are classified by anatomoclinical picture and target antigen. A new entity has recently been identified: anti-p200 pemphigoid.

PATIENTS AND METHODS

An 82-year-old man consulted for a profuse pruritic bullous eruption refractory to the standard treatments for bullous pemphigoid (BP). Direct immunofluorescence examination of a skin biopsy revealed linear deposits of IgG and of C3 at the dermal-epidermal junction, but Elisa screening for circulating anti-BP180 and anti-BP230 antibodies was negative. Indirect immunofluorescence (IIF) testing of cleaved skin revealed a deposit of IgG4 antibodies on the dermal side. Immunoblotting was negative for a dermal extract but showed an antibody directed against a 200-kD epidermal antigen. A diagnosis of anti-p200 pemphigoid was eventually made and the patient was successfully treated with dapsone.

DISCUSSION

The diagnosis of anti-p200 pemphigoid was made in this case in spite of discrepancy between the IIF and immunoblotting results, and despite the fact that the target antigen in this disease is considered as being restricted to dermal sites. Anti-p200 pemphigoid usually begins in the second part of life and differs from standard bullous pemphigoid in terms of more frequent mucous membrane and cephalic involvement, as well as a greater degree of miliary scarring. This disease appears more prominent in males and is associated with psoriasis in around one third of cases. Autoantibodies recognize laminin gamma-1, an extra-desmosomal protein that contributes to dermal-epidermal adhesion.

CONCLUSION

This recently described disease as probably under-diagnosed in France. It should be considered in atypical presentations of bullous disease. Diagnosis is confirmed by immunoblotting detection of autoantibodies directed against a 200-kD antigen normally present in the extract. Dapsone appears to be the most effective treatment.