Takekuni Nakama

Epidermolysis bullosa acquisita: What's new?

Type VII collagen is an adhesion molecule of the extracellular matrix in epithelial basement membranes, and the main constituent of anchoring fibrils at the dermal–epidermal junction (DEJ). Autoimmunity against this protein is causing the rare organ‐specific epidermolysis bullosa acquisita (EBA). EBA is a rare acquired, heterogeneous, chronic blistering disease of skin disease of skin and mucous membranes characterized by subepidermal blisters and tissue‐bound as well as circulating autoantibodies to the DEJ. EBA has several distinct clinical presentations with other subepidermal bullous diseases, such as mainly dystrophic epidermolysis bullosa or bullous pemphigoid. The circulating immunoglobulin G autoantibodies for EBA react with a 290‐kDa dermal protein, type VII collagen, as detected by immunoblot analysis using dermal extracts. The pathogenicity of these autoantibodies has been demonstrated by experimental animal models, in which anti‐type VII collagen antibodies injected into a mouse produced an EBA‐like blistering disease in the animal. EBA cases often require high doses of systemic corticosteroids and a variety of immunosuppressants. Although treatment for EBA is frequently difficult and unsatisfactory, some therapeutic success has been reported with colchicine, dapsone, infliximab and i.v. immunoglobulin. In this review, we will focus on recent progress in our understanding of the clinical manifestations, the etiopathogenesis as well as the management of EBA.

From anti-p200 pemphigoid to anti-laminin γ1 pemphigoid

Anti‐laminin γ1 pemphigoid is an autoimmune subepidermal bullous disease first described in 1996, and has been distinct from previously known subepidermal blistering diseases, such as bullous pemphigoid and epidermolysis bullosa acquisita. Circulating autoantibodies of the patients do not react to any known autoantigen of the skin, but react to a 200‐kDa molecule (p200) from dermal extracts. The identity of p200 was unmasked as laminin γ1, an extracellular matrix glycoprotein composing several forms of laminin heterotrimers. We renamed this disease from the previously used anti‐p200 pemphigoid to anti‐laminin γ1 pemphigoid, a new entity of an autoimmune bullous disease. In this decade, we have experienced over 70 cases of this disease. Although the number of the cases of anti‐laminin γ1 pemphigoid is half as many as the number of definitely diagnosed cases of epidermolysis bullosa acquisita in the same duration, a considerable number of the cases could be clinically misdiagnosed as epidermolysis bullosa acquisita. Unveiling the pathogenicity and development of a useful diagnostic method is necessary for appropriate management of this new disease.

Lesional Th17 cells and regulatory T cells in bullous pemphigoid

Abstract:  Th17 cells play crucial roles in the pathogenesis of autoimmune diseases. We previously reported that Th17 cells are recruited to the lesional skin in pemphigus vulgaris (PV) and pemphigus foliaceus (PF). The aim of this study was to evaluate lesional Th17 cells and Treg cells in bullous pemphigoid (BP). Correlations between these cells and disease severity of BP were also evaluated. Immunohistochemical studies showed that both IL‐17+ and Foxp3+ cells were present in higher numbers in BP lesions, compared with control skin. IL‐17/CD4 ratio in BP was significantly higher than that in PF. Foxp3/CD4 ratio in BP was significantly less than that in either PV or PF. There were no obvious correlations between these cells and disease severity of BP. This study suggests that, compared with pemphigus, BP shows more Th17 cell‐related inflammation and less Treg‐related regulation.

Serum Levels of Eosinophil Cationic Protein Reflect the State of In vitro Degranulation of Blood Hypodense Eosinophils in Atopic Dermatitis

In patients with atopic dermatitis (AD), serum levels of eosinophil cationic protein (ECP) have been shown to be a good reflector of disease severity. To elucidate what serum levels of ECP actually reflect, ECP levels in serum and plasma and cytological aspects of blood eosinophils were examined in AD patients (n=27) and compared to healthy subjects (n=12). Significantly elevated levels of serum ECP were noted in AD patients, while plasma ECP were uniformly recorded at nadir levels in both AD patients and normal subjects. In addition to blood eosinophilia, AD patients had significantly increased numbers of hypodense eosinophils (HEo) with morphological characteristics consistent with an activated state. Serum ECP levels strongly correlated with HEo numbers rather than with total eosinophil counts. These results indicate that elevated levels of serum ECP may be a consequence of in vitro degranulation of “activated” HEo, not of ECP supplementation from lesional skin. In addition, the dynamic correlations of eosinophil‐associated parameters (total eosinophil counts, HEo numbers, and serum ECP levels) with AD severity suggest that inflammatory events in lesional skin may be involved in causing not only eosinophilopoiesis in bone marrow, but also development of HEo in the periphery, whose degree in turn may be mirrored in the levels of serum ECP in vitro.

Clinicopathological features and prognostic significance of CXCL12 in blastic plasmacytoid dendritic cell neoplasm

BACKGROUND Blastic plasmacytoid dendritic cell neoplasm (BPDC) is a rare hematologic neoplasm, which almost always involves the skin and shows poor prognosis. OBJECTIVE The aim of our study was to enhance BPDC diagnosis and indications for prognosis. METHODS This study involved 26 patients with BPDC. To investigate the histogenesis of BPDC, we reviewed the clinical features and stained markers of various hematopoietic lineages, chemokines, and their receptors. RESULTS Bone-marrow infiltration was detected in 13 of the 19 cases examined and leukemic changes in 18. Complete remission was achieved in 14 cases, but more than half of the patients showed recurrence within a short time, and 14 patients died of the disease after 1 to 25 months (mean 8.5 months). Positivity for CD123 was detected in 18 of 24 cases and for T-cell leukemia 1 in 18 of 22 cases. Of the chemokines and their receptors, 8 of 15 skin biopsy specimens proved to be positive for CXCL12. Leukemic change subsequent to skin lesions occurred in 7 of 8 CXCL12-positive cases (87.5%) and in 3 of 6 CXCL12-negative cases (50%). Seven of the 8 CXCL12-positive patients (87.5%) and two of the 6 CXCL12-negative patients (33.3%) have died, whereas one of 8 CXCL12-positive patients (12.5%) and 4 of 6 CXCL12-negative patients (66.7%) remain alive. LIMITATIONS The number of patients was limited. CONCLUSIONS We speculate that the presence of CXCL12-positive cells in the skin may be associated with leukemic change and a poor prognosis.

A clinical study of patients with pemphigus vulgaris and pemphigus foliaceous: an 11‐year retrospective study (1996–2006)

Only a few reports have been published of detailed clinical studies of pemphigus in Japan. The aim of this study was to determine the clinical characteristics of patients with pemphigus vulgaris (PV) and pemphigus foliaceous (PF), who were newly diagnosed in the dermatology department of Kurume University Hospital, Japan, over the past 11 years. The primary site of involvement was the oral mucosa in 21 patients (75%) with PV. At the initial visit, most of the patients with PV had moderate to severe disease. With regard to management, systemic corticosteroids were the mainstay of treatment for patients with PV, and plasmapheresis was the most frequently used adjuvant therapy. Dapsone was the mainstay of treatment for the patients with PF. The patients were investigated for any association with an underlying malignancy; in patients with PV, lung, stomach and uterine cancers (one patient each) were seen.

Anti-Alpha-2-Macroglobulin-Like-1 Autoantibodies Are Detected Frequently and May Be Pathogenic in Paraneoplastic Pemphigus

Paraneoplastic pemphigus (PNP) shows autoantibodies mainly to plakin and desmosomal cadherin family proteins. We have recently identified alpha-2-macroglobulin-like-1 (A2ML1), a broad range protease inhibitor, as a unique PNP antigen. In this study, we tested a large number of PNP sera by various methods. Forty (69.0%) of 58 PNP sera recognized A2ML1 recombinant protein expressed in COS7 cells by immunofluorescence (IF) and/or immunoprecipitation (IP)/immunoblotting (IB). IP/IB showed higher sensitivity than IF. In addition, 22 (37.9%) PNP sera reacted with A2ML1 by IB of cultured normal human keratinocytes (NHKs) under non-reducing conditions. Statistical analyses using various clinical and immunological data showed that the presence of anti-A2ML1 autoantibodies was associated with early disease onset and absence of ocular lesions. Next, to investigate the pathogenic role of anti-A2ML1 antibody, we performed additional functional studies. Addition of anti-A2ML1 polyclonal antibody to culture media decreased NHK cell adhesion examined by dissociation assay, and increased plasmin activity detected by casein zymography, suggesting that anti-A2ML1 antibody may decrease NHK cell adhesion through plasmin activation by inhibition of A2ML1. This study demonstrates that autoantibodies to A2ML1 are frequently and specifically detected and may have a pathogenic role in PNP.

Interaction of plectin and intermediate filaments.

BACKGROUND Plectin, a member of the plakin family proteins, is a high molecular weight protein that is ubiquitously expressed. It acts as a cytolinker for the three major components of the cyotoskeleton, namely actin microfilaments, microtubules and intermediate filaments. OBJECTIVE The aim of our experiments was to identify new binding sites for intermediate filaments on plectin and to specify these sites. METHODS We introduced truncated forms of plectin into several cell lines and observe interaction between plectin and intermediate filaments. RESULTS We found that a linker region in the COOH-terminal end of plectin was required for the association of the protein with intermediate filaments. In addition, we also demonstrated that a serine residue at position 4645 of plectin may have a role on binding of plectin to intermediate filaments. CONCLUSION A linker region in the COOH-terminal end and serine residue at position 4645 may be important for the binding of plectin to intermediate filaments.

Eosinophil Phenotypes in Bullous Pemphigoid

Eosinophil phenotypes were investigated in peripheral blood and skin lesions from eight patients with bullous pemphigoid (BP). By Nycodenz density gradients fractionation, blood eosinophils were divided into two phenotypes; normodense (>1.080 g/ml) and hypodense (>1.080 g/ml). Increased numbers of hypodense eosinophils were observed in the blood from all patients with BP. Immunocytochemical observations, using an EG2 monoclonal antibody to react with the secretion form of eosinophil cationic protein (ECP), revealed that EG2 was expressed in 86 ± 3% of hypodense phenotypes and 3 ± 2% of normodense phenotypes. Ultrastructurally, hypodense eosinophils were characterized by numerous spheroidal granules, each with a lytic crystalloid core. These indicate that the hypodense phenotype represents a cell in an activated state. Only eosinophils with immunocytochemical and morphological characteristics similar to hypodense phenotypes infiltrated around the basement membrane zone in involved skin of BP. Furthermore, direct adherence of eosinophils associated with degranulation into basal keratinocytes was seen at the sites of blistering lesions. Bullous fluids contained higher concentrations of ECP than sera as determined by a radioimmunosorbent assay; thus hypodense (activated) eosinophils may directly damage the basal keratinocytes by releasing their granule proteins, subsequently leading to dermo‐epidermal separation.

Mizoribine treatment for antihistamine‐resistant chronic autoimmune urticaria

Chronic autoimmune urticaria is routinely diagnosed using an autologous serum skin test. Mizoribine is a newly developed immunosuppressive agent that has low toxicity. The pharmacological effects of mizoribine are similar to those of another purine biosynthesis inhibitor, mycophenolate mofetil. A 57‐year‐old woman presented with recurrent wheals and was insufficiently managed with administration of antihistamines, antileukotrienes, oral corticosteroids, and cyclosporine. She was positive in the autologous serum skin test. Oral mizoribine therapy was started as a combination therapy with prednisolone. The patient achieved a dramatic improvement in symptoms and complete resolution of the urticaria a few days after adding mizoribine to her treatment. The prednisolone was tapered after the start of mizoribine treatment. Her symptoms did not flare up, and no side effects were observed. In vitro basophil histamine release assays suggested that she might have anti‐IgE autoantibody‐type histamine release activity. We believe that mizoribine has a therapeutic role in some patients with chronic autoimmune urticaria and may be useful for treatment of cases not responsive to classical therapy. We suggest that mizoribine might help to reduce anti‐IgE autoantibody acting on the surface of basophils in chronic autoimmune urticaria.