Electron microscopy and histochemistry of pemphigus and pemphigoid

Bullous Pemphigoid IgG Induces Cell Dysfunction and Enhances the Motility of Epidermal Keratinocytes via Rac1/Proteasome Activation

Bullous pemphigoid (BP) is an autoimmune disease characterized by the formation of blisters, in which autoantibodies mainly target type XVII collagen (ColXVII) expressed in basal keratinocytes. BP IgG is known to induce the internalization of ColXVII from the plasma membrane of keratinocytes through macropinocytosis. However, the cellular dynamics following ColXVII internalization have not been completely elucidated. BP IgG exerts a precise effect on cultured keratinocytes, and the morphological/functional changes in BP IgG-stimulated cells lead to the subepidermal blistering associated with BP pathogenesis. Based on the electron microscopy examination, BP IgG-stimulated cells exhibit alterations in the cell membrane structure and the accumulation of intracellular vesicles. These morphological changes in the BP IgG-stimulated cells are accompanied by dysfunctional mitochondria, increased production of reactive oxygen species, increased motility, and detachment. BP IgG triggers the cascade leading to metabolic impairments and stimulates cell migration in the treated keratinocytes. These cellular alterations are reversed by pharmacological inhibitors of Rac1 or the proteasome pathway, suggesting that Rac1 and proteasome activation are involved in the effects of BP IgG on cultured keratinocytes. Our study highlights the role of keratinocyte kinetics in the direct functions of IgG in patients with BP.

Ultrastructural studies of acantholysis induced in vivo by passive transfer of IgG from endemic pemphigus foliaceus (Fogo Selvagem)

Intraperitoneal (IP) injections of IgG from patients with Endemic Pemphigus Foliaceus [Fogo Selvagem (FS)] cause acantholysis in BALB/c mice (JID. 85:538, 1985). The dynamic ultrastructural changes of FS IgG-induced acantholysis in mice are the subject of this study. FS IgG was injected IP into neonatal BALB/c mice. Skin and serum was studied at 0, 1, 3, 6, 12, 18, and 24 h post injection by immunofluorescence (IF), electron microscopy (EM), and immuno-EM. Binding of FS IgG in the intercellular spaces (ICS) of the basal cell layer was seen by IF within 1 h and was strongest at 12 h. IgG binding affected the spinous and granular cell layer by 12 h, then faded and remain localized only in the basal cell layer at 24 h. By immuno-EM, IgG binding was diffuse along the keratinocyte surface. Edema of the ICS in the basal cell layer was present at 1 h by EM. At 12 h, there was microvillous formation with intact desmosomes at the tip of the projections. Splitting of desmosomes (forming half desmosomes) and acantholysis primarily affecting the granular cell layer were most prominent between 12 and 24 h. The plaques of the half desmosomes gradually disappeared and tonofilaments retracted into the cytoplasm. Detaching keratinocytes showed vacuolization, swollen mitochondria, and internalization of intact desmosomes and half desmosomes (remnants of split desmosomes). This investigation shows that the ultrastructural changes observed in the epidermis of patients with FS can be duplicated in experimental animals by IP injection of FS IgG. Further, FS IgG may have direct effects on the assembly/disassembly of desmosomes.

Pathogenetic studies in bullous pemphigoid--review of the literature and our own results

Bullous pemphigoid (bP) is a blister‐forming disease, probably of autoimmune nature. Its genetic background has not been established yet. Associations with other autoimmune diseases and, to some extend, with malignant tumors are noteworthy. The blisters are located subepidermally in the lamina lucida between the cytoplasmic membrane of the basal cells and the lamina densa of the basement membrane. The bP antigen, which is produced by basal cells, serves as an attachment factor and can be liberated into the blister fluid, probably by serine proteases from leucocytes. The formation of antigen‐antibody complexes is favoured afterwards. Freely circulating bP antibodies, mostly of the IgG class, are fixed in the skin tissue in vivo and in vitro and bind complement. Components of the classical complement pathway as well as of the amplification loop are activated locally in the skin tissue and fixed. The content of immune complexes is increased in the serum and in the blister fluid. They partially consist of specific bP antigen‐antibody complexes. The determination of the entire bP antibody titer (after immune complex splitting) correlates well with the clinical course of the disease.

Chemotactic factors for neutrophils and eosinophils are released into the blister fluid after complement activation, so that leucocyte attraction is mediated. Deviations of humoral and cellular immune reactivity have not been studied sufficiently. There might be an immune modulating effect of immune complexes and other serum factors on T‐lymphocytes due to steric hindrance of surface receptors. In vivo and in vitro models in rabbit cornea, skin explants, and frozen sectioned skin tissue suggest that the interaction of circulating bP antibodies with the bP antigen followed by complement activation and attraction of neutrophils might be the primary immunopathological mechanism, producing an immune complex mediated inflammation.

Surgical approach to the treatment of refractory lesions of pemphigus vulgaris

A patient with pemphigus vulgaris had lesions on the lip that proved to be refractory to intralesional corticosteroid therapy and to treatment with azathioprine and later to daily administration of 250 mg of prednisone. The patient developed marked cushingoid features and deep vein thrombosis, rendering the continuation of the prednisone therapy unadvisable . Total vermilionectomy of the affected lip was performed and the prednisone was gradually tapered, taking care that oral lesions remained under control. Eighteen months after the operation, the patient is receiving a single alternate-daily dose of 20 mg prednisone, and both the lip and oral lesions are in remission.

Chronic pemphigus vulgaris of the gingiva. A case report with a 6-year follow-up

Since the initial lesions of pemphigus vulgaris often appear in the oral cavity, dentists have a major role in the recognition and diagnosis of this condition. The patient reported here was seen with a mild gingival form of the disease and has been managed successfully for the past 6 years without systemic steroids and with minimal topical steroid therapy. For most of that period he was managed without medication. Various aspects of the disease, including diagnosis, the significance of pemphigus antibodies and therapy are reviewed to provide a better perspective on this case.

Acantholytic cells in pemphigus. A scanning and transmission electron microscopic study

Scanning electron microscopy (SEM) was performed on oral scrapings from seven patients with pemphigus vulgaris and one with pemphigus vegetans as well as on skin samples from one of those with pemphigus vulgaris. The unstained, fixed, critical-point dried cells were identified with the aid of a light microscope. On the basis of the surface appearance, three main types of acantholytic cells were identified: smooth-surfaced, wrinkled, and microvillous. The acantholytic cells were rounded to ovoid and some showed either a central bulging or a concavity. Small, rounded to ovoid holes or indentations (diameter 0.1-0.3 mumol) were observed on most cell surfaces. The surfaces of acantholytic cells were occasionally occupied by a few micro-organisms. Neutrophilic polymorphonuclear leucocyte/acantholytic cell rosettes were studied by SEM. No gap between acantholytic cell and surrounding leucocytes could be demonstrated. It is postulated that neutrophils may mediate the cytolysis of antibody-coated acantholytic cells. Oral scrapings from one patient with pemphigus vulgaris were collected for transmission electron microscopy (TEM). The acantholytic cells were rounded or ovoid and usually had centrally placed nuclei. Tonofilaments were either randomly distributed or concentrically arranged around the nucleus. In other acantholytic cells there was a halo containing vesicles of varying size around the nucleus. TEM findings suggest that acantholytic cells represent dead or dying cells. Both TEM and SEM findings suggest that when acantholytic cells first separate they may show variable numbers of microvilli, which are probably lost in older acantholytic cells.