Duco Kramer

Laboratory diagnosis of paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) is a multiorgan disease characterized by antibodies against plakins, desmogleins and the α2‐macroglobulin‐like‐1 (A2ML1) protein, in association with an underlying neoplasm. Accurate diagnosis relies on the demonstration of these autoantibodies in serum.

Large-Scale Electron Microscopy Maps of Patient Skin and Mucosa Provide Insight into Pathogenesis of Blistering Diseases.

Large-scale electron microscopy (nanotomy) allows straight forward ultrastructural examination of tissue, cells, organelles, and macromolecules in a single data set. Such data set equals thousands of conventional electron microscopy images and is freely accessible (www.nanotomy.org). The software allows zooming in and out of the image from total overview to nanometer scale resolution in a Google Earth approach. We studied the life-threatening human autoimmune blistering disease pemphigus, using nanotomy. The pathomechanism of cell-cell separation (acantholysis) that underlies the blistering is poorly understood. Ultrastructural examination of pemphigus tissue revealed previously unreported findings: (i) the presence of double-membrane structures between cells in all pemphigus types; (ii) the absence of desmosomes around spontaneous blisters in pemphigus foliaceus (PF); (iii) lower level blistering in PF when force induced; and (iv) intercellular widening at non-acantholytic cell layers. Thus, nanotomy delivers open-source electron microscopic maps of patient tissue, which can be analyzed for additional anomalies from any computer by experts from different fields.

Smaller Desmosomes Are Seen in the Skin of Pemphigus Patients with Anti-Desmoglein 1 Antibodies but Not in Patients with Anti-Desmoglein 3 Antibodies

TO THE EDITOR Pemphigus is a chronic mucocutaneous autoimmune blistering disease caused by autoantibodies directed against the desmosomal cadherins, desmoglein 1 (Dsg1) and/or desmoglein 3 (Dsg3). In patients with pemphigus foliaceus (PF), there is superficial blistering of the skin but not of mucous membranes, with autoantibodies directed against Dsg1. In mucosal-dominant pemphigus vulgaris (mdPV), mucous membranes are involved but not the skin, with autoantibodies directed against Dsg3. Mucocutaneous PV (mcPV) is characterized by suprabasal blistering of both the skin and mucous membranes, with autoantibodies directed against both Dsg1 and Dsg3. Desmosomes are intercellular adhering discoid junctions serving to attach neighboring cells to each other. Their diameter varies between 0.2 and 0.7mm in the epidermis. During epidermal differentiation, smaller, less well-organized desmosomes in the basal cells are replaced by larger, more electron-dense structures in the upper layers (Odland, 1958; Green and Simpson, 2007; Holthofer et al., 2007; Scothern and Garrod, 2008). Desmosomes are composed of members of at least three protein families. Desmosomal cadherins (desmogleins and desmocollins) constitute the transmembrane adhesive interface, whereas armadillo and plakin family proteins build up the cytoplasmic plaques. The cytoplasmic tail of the transmembrane desmogleins and desmocollins interacts with plakoglobin, which in turn binds to desmoplakin. Desmoplakin anchors to the intermediate filaments. The interactions are stabilized laterally by plakophilin (Green and Simpson, 2007; Waschke, 2008). In pemphigus, both anti-Dsg1 and antiDsg3 antibodies can cause acantholysis, although the actual pathomechanism is unknown. Current theories include steric hindrance, desmosomal non-assembly and disassembly, or cell signaling. We recently described the ultrastructure of the epidermis in PF patients (Van der Wier et al., 2012). We found no abnormalities in the desmosomes or in the intercellular distance in Nikolskynegative (N ) PF skin, whereas in Nikolsky-positive (Nþ ) PF skin we observed intercellular widening between the desmosomes and a slight reduction in the size and number of desmosomes in the lower epidermal layers but not in the higher ones. Full acantholysis was only observed in lesional PF skin due to a severe reduction in the size and number of desmosomes in the higher epidermal layers (Van der Wier et al., 2012). In the present study, we performed morphometric studies on the skin of PF, mdPV, and mcPV patients to determine the influence of Dsg1 and Dsg3 autoantibodies on the number and length of desmosomes. We correlated the morphometric data to the immunofluorescence staining pattern of the most important immunological effectors in pemphigus: IgG, Dsg1, and Dsg3. Skin biopsies of two human controls, and eight pemphigus patients were studied. The skin biopsies were taken from N or Nþ non-lesional skin from four Accepted article preview online 12 March 2014; published online 17 April 2014 Abbreviations: Dsg1, desmoglein 1; Dsg3, desmoglein 3; ECS, epithelial cell surface; mcPV, mucocutaneous pemphigus vulgaris; mdPV, mucosal-dominant pemphigus vulgaris; N , Nikolsky negative; Nþ , Nikolsky positive; PF, pemphigus foliaceus; PV, pemphigus vulgaris G van der Wier et al. Desmosomes in Pemphigus

Keratolysis exfoliativa (dyshidrosis lamellosa sicca): a distinct peeling entity

Backgroundu2002 Keratolysis exfoliativa (KE), also known as dyshidrosis lamellosa sicca, is a palmoplantar dermatosis characterized by air‐filled blisters and collarette desquamation. It has been regarded as a subtype of dyshidrotic eczema, a fungal infection or a dermatophytid reaction. KE may also resemble acral peeling skin syndrome and localized epidermolysis bullosa simplex. Although KE is a common disorder, it is a rarely reported and is an under‐recognized dermatosis.

Murine type VII collagen distorts outcome in human skin graft mouse model for dystrophic epidermolysis bullosa

Human skin graft mouse models are widely used to investigate and develop therapeutic strategies for the severe generalized form of recessive dystrophic epidermolysis bullosa (RDEB), which is caused by biallelic null mutations in COL7A1 and the complete absence of type VII collagen (C7). Most therapeutic approaches are focused on reintroducing C7. Therefore, C7 and anchoring fibrils are widely used as readouts in therapeutic research with skin graft models. In this study, we investigated the expression pattern of human and murine C7 in a grafting model, in which human skin is reconstituted out of in vitro cultured keratinocytes and fibroblasts. The model revealed that murine C7 was deposited in both human healthy control and RDEB skin grafts. Moreover, we found that murine C7 is able to form anchoring fibrils in human grafts. Therefore, we advocate the use of human‐specific antibodies when assessing the reintroduction of C7 using RDEB skin graft mouse models.