抗天疱疮抗体阻断棘层松解的实验研究

目的 研究抗天疱疮抗体对天疱疮抗体棘层松解的阻断作用,探讨天疱疮治疗的新途径。方法 制备出小鼠抗天疱疮抗体,在体外天疱疮器官培养基础上,采用病理学及直接免疫荧光技术,观察不同浓度及时相抗天疱疮抗体对天疱疮抗体致棘层松解的阻断效果。结果 抗天疱疮抗本在体外与天疱疮抗体结合后,能有效地减少天疱疮抗体与角质形成细胞的结合,小剂量时能减轻天疱疮抗体致棘层松解的程度,大剂量时则能基本阻断棘层松解的发生。结论 抗天疱疮抗体与天疱疮抗体结合后能有效地减轻或阻断棘层松解的发生。     

Synergistic actions of pemphigus vulgaris IgG,Fas-ligand and tumor necrosis factor-α during induction of basal cell shrinkage and acantholysis

This study tested a recently proposed “Basal Cell Shrinkage” hypothesis of pemphigus acantholysis through a quantitative analysis of individual and cooperative effects of pemphigus vulgaris (PV) IgG, Fas-ligand (Fas-L) and tumor necrosis factor-α (TNFα) on keratinocyte (KC) volume (i.e. cell size) and adhesive properties. Exposure of KC monolayers and MatTek EpiDermFT? tissues cultures to the physiologic concentrations of Fas-L, TNFα or IgGs from two PV patients resulted in various degrees of reversible changes, which were not observed in control cultures either exposed to normal IgG or left intact. Within 12–24 h of exposure, basal cells in experimental cultures lost their ability to form stress fibers, retracted cytoplasmic aprons and formed keratin aggregates, indicating that their cytoskeleton collapsed. The cell volume decreased significantly (p < 0.05) as the polygonal cell shape changed to a round one. The shrunk cells detached from their neighbors and the substrate, resulting in a reciprocal increase of both the areas of acantholysis and the number of detached KCs, respectively. Since in the skin of PV patients, KCs are targeted by autoantibodies concomitantly with being exposed to autocrine and paracrine pro-apoptotic and pro-inflammatory cytokines, we combined PV IgG with Fas-L and/or TNFα in the cell culture experiments. This amplified several fold an ability of PV IgG to cause basal cell shrinkage and detachment. The obtained results demonstrated for the first time that PV IgG works together with Fas-L and TNFα to induce acantholysis via basal cell shrinkage, which provides a novel mechanism explaining successful treatment of PV patients with TNFα inhibitors.     

Calcium pumps and keratinocytes: lessons from Darier's disease and Hailey-Hailey disease

Darier's disease and Hailey-Hailey disease are autosomal dominantly inherited skin disorders in which desmosomal adhesion between keratinocytes is abnormal. ATP2A2 and ATP2C1 have been identified as the causative genes for Darier's disease and Hailey-Hailey disease, respectively. ATP2A2 encodes the sarco(endo)plasmic reticulum Ca(2+)-ATPase isoform 2 (SERCA2) pump, while ATP2C1 encodes a secretory pathway Ca(2+)/Mn(2+)-ATPase (SPCA1) found in the Golgi apparatus. We review recent work into the function of these pumps in human keratinocytes and discuss how mutations in these genes might cause these diseases by altering the formation or stability of desmosomes.     

Apoptolysis: a novel mechanism of skin blistering in pemphigus vulgaris linking the apoptotic pathways to basal cell shrinkage and suprabasal acantholysis

Abstract:  Understanding the acantholytic pathways leading to blistering in pemphigus vulgaris (PV) is a key to development of novel treatments. A novel paradigm of keratinocyte damage in PV, termed apoptolysis, links the suprabasal acantholytic and cell death pathways to basal cell shrinkage rendering a 'tombstone' appearance to PV lesions. In contrast to apoptolysis, the classic keratinocyte apoptosis mediating toxic epidermal necrolysis causes death and subsequent sloughing of the entire epidermis. Apoptolysis includes five consecutive steps. (1) Binding of autoantibodies to PV antigens. (2) Activation of EGF receptor, Src, mTOR, p38 MAPK and other signalling elements downstream of ligated antigens, elevation of intracellular calcium and launching of the cell death cascades. (3) Basal cell shrinkage due to: (i) collapse and retraction of the tonofilaments cleaved by executioner caspases; and (ii) dissociation of interdesmosomal adhesion complexes caused by phosphorylation of adhesion molecules. (4) Massive cleavage of cellular proteins by activated cell death enzymes leading to cell collapse, and tearing off desmosomes from the cell membrane stimulating secondary autoantibody production. (5) Rounding up and death of acantholytic cells. Thus, the structural damage (acantholysis) and death (apoptosis) of keratinocytes are mediated by the same cell death enzymes. Appreciation of the unifying concept of apoptolysis have several important implications: (i) linking together a number of seemingly unrelated events surrounding acantholysis; (ii) opening new avenues of investigation into the pathomechanism of pemphigus; and (iii) creating new approaches to the treatment of pemphigus based on blocking the signalling pathways and enzymatic processes that lead to blistering.     

Neural nitric oxide synthase participates in pemphigus vulgaris acantholysis through upregulation of Rous sarcoma,mammalian target of rapamycin and focal adhesion kinase

Pemphigus vulgaris (PV) is an autoimmune blistering skin disease characterized by suprabasal acantholysis produced as a consequence of desmoglein (Dsg) and non‐Dsg autoantibodies binding to several targeting molecules localized on the membrane of keratinocytes. Nitric oxide (NO) may exert a pathogenic function in several immunological processes. We have previously demonstrated that neural nitric oxide synthase (nNOS) plays part in PV acantholysis. Also, our group has described a relevant role for HER [human epidermal growth factor receptor (EGFR) related] isoforms and several kinases such as Src (Rous sarcoma), mammalian target of rapamycin (mTOR) and focal adhesion kinase (FAK), as well as caspases in PV development. Using a passive transfer mouse model of PV, we aimed to investigate the relationship between the increase in nNOS and EGFR, Src, mTOR and FAK kinase upregulation observed in PV lesions. Our results revealed a new function for nNOS, which contributes to EGFR‐mediated PV acantholysis through the upregulation of Src, mTOR and FAK. In addition, we found that nNOS participates actively in PV at least in part by increasing caspase‐9 and caspase‐3 activities. These findings underline the important issue that in PV acantholysis, caspase activation is a nNOS‐linked process downstream of Src, mTOR and FAK kinase upregulation.     

Paraneoplastic Pemphigus: Report of a Case

A 56-year-old male with chronic lymphocytic leukemia developed extensive erosive mucocutaneous lesions with histologic acantholysis. Immunopathologic studies showed IgG deposition at the intercellular space, C3 deposition at both the intercellular space and the dermo-epidermal junction, and reactivity of the serum to rat urinary bladder epithelium. Autoantibodies in the serum to human epidermal proteins of 210 kD and 190 kD were shown by Western blotting and to proteins of 250 kD, 210 kD, and 190 kD by immunoprecipitation. All these data suggest the diagnosis of paraneoplastic pemphigus. Repeated plasmapheresis resulted in re-epithelialization of the mucocutaneous lesions and reduction in antibody titer from 1:1280 to 1:20. Although this mucocutaneous disease was established as a new autoimmune bullous disease by Anhalt et al. (1990), cases have rarely been reported from Japan. The present patient demonstrates the major characteristics of paraneoplastic pemphigus.     

A Case of Pseudovascular Adenoid Squamous Cell Carcinoma of the Skin with Spindle Cell Pattern

We report a case of pseudovascular adenoid squamous cell carcinoma which was in the form of a dome-shaped, cherry red tumor on the right cheek of an 86-year-old Japanese woman. Histologically, two types of atypical cells were identified; round cells in the upper part and spindle cells in the lower part. In the upper part, inter-anastomosing sinusoid-like pseudolumina were observed between the cords of the tumor cells. Immunohistochemically, the tumor cells did not express Factor VIII-related and CD34 antigens or bind Ulex europaes I agglutinin, except for only one anti-cytokeratin antibody. Ultrastructurally, the tumor cells contained tonofilaments and desmosomes and represented acantholysis. From the electron microscopy, possible role of capillary hyperpermeability on the acantholytic process of the neoplastic cells was suggested.