Usefulness of BP230 and BP180-NC16a enzyme-linked immunosorbent assays in the initial diagnosis of bullous pemphigoid: a retrospective study of 138 patients

OBJECTIVE

To investigate the diagnostic value of commercially available BP230 and BP180-NC16a enzyme-linked immunosorbent assays (ELISAs) in routine practice in patients with bullous pemphigoid (BP).

DESIGN

Single-center retrospective study.

SETTING

French academic dermatology department.

PATIENTS

The study population comprised 138 patients, who were admitted from January 1998 through December 2008.

INTERVENTIONS

Sera samples were analyzed by ELISA; clinical and immunopathological data were recorded from the patients' medical charts.

MAIN OUTCOME MEASURES

BP230 and BP180-NC16a ELISA scores were evaluated with respect to clinical characteristics (number of blisters, mucosal involvement, localized or generalized disease, and outcome) and routine indirect immunofluorescence (IF).

RESULTS

Of the 138 study patients, 81 (59%) had a positive BP230 ELISA result and 119 (86%) had a positive BP180 ELISA result. There was no relationship between a positive ELISA BP230 result and the disease extent at diagnosis or the presence of mucosal involvement. Serum anti-basement membrane zone autoantibodies (indirect IF) were more frequently detected when the BP230 ELISA result was positive (P < .001). The median anti-basement membrane autoantibody titer as detected by indirect IF was higher in patients with a positive BP230 result (P < .001). The BP180 ELISA result was associated with disease extent at diagnosis as estimated by both the percentage of patients with extensive BP (P = .01) and the mean number of blisters (P = .03) but was not associated with mucosal involvement.

CONCLUSIONS

The currently available BP230 ELISA is a reliable although less-sensitive test than BP180 ELISA in BP, and its diagnostic added value compared with BP180 ELISA alone is approximately 5%. Our results support the predominant contribution of the BP230-specific autoantibodies to anti-basement membrane zone antibody titer as detected by indirect IF.

Enzyme-linked immunosorbent assay for the combination of bullous pemphigoid antigens 1 and 2 in the diagnosis of bullous pemphigoid

OBJECTIVE

To assess the usefulness of enzyme-linked immunosorbent assay (ELISA) assessment of the combination of bullous pemphigoid antigen 1 (BPAG1) and BPAG2 in the diagnosis of bullous pemphigoid (BP).

DESIGN

Retrospective study of serum samples from patients with BP.

SETTING

Tertiary care center.

PATIENTS

A total of 190 patients with newly diagnosed BP and 78 controls with other autoimmune bullous diseases.

INTERVENTION

Serum samples were tested using commercialized BPAG1 and BPAG2 ELISA and indirect immunofluorescence (IIF).

MAIN OUTCOME MEASURES

The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 in the diagnosis of BP were contrasted with ELISA for each of the antigens alone and with IIF.

RESULTS

The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 were 87% and 88%, respectively, compared with 79% and 90% for BPAG2 ELISA, 61% and 96% for BPAG1 ELISA, and 81% and 63% for IIF. The combination of BPAG1 ELISA and BPAG2 ELISA permitted 8% and 16% gains in sensitivity compared with each of BPAG2 ELISA and BPAG1 ELISA alone, respectively. Anti-BPAG1 antibodies were detected in 15 of 40 BP serum samples with no anti-BPAG2 antibodies (38%) and in 8 of 13 serum samples from patients with BP and mucosal involvement (62%) compared with 2 of 22 samples of cicatricial pemphigoid (P = .002) and 0 of 16 epidermolysis bullosa acquisita serum samples (P < .001). The BPAG2 ELISA values were more closely correlated with initial extent of BP lesions (r = 0.44, P < .001) than BPAG1 ELISA values (r = 0.16, P = .03).

CONCLUSION

Since the combination of BPAG1 and BPAG2 ELISA only slightly increases the sensitivity of BP diagnosis over BPAG2 ELISA alone, BPAG1 ELISA could be adequately proposed in a minority of BP cases with mucosal involvement and in those with no circulating anti-BPAG2 antibodies.

Relationship between target antigens and major histocompatibility complex (MHC) class II genes in producing two pathogenic antibodies simultaneously

In this report,we present 15 patients with histological and immunopathologically proven pemphigus vulgaris (PV). After a mean of 80 months since the onset of disease, when evaluated serologically, they had antibodies typical of PV and pemphigoid (Pg). Similarly, 18 patients with bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP) were diagnosed on the basis of histology and immunopathology.After a mean of 60 months since the onset of disease, when their sera were evaluated they were found to have Pg and PV autoantibodies. In both groups of patients the diseases were characterized by a chronic course, which included several relapses and recurrences and were non-responsive to conventional therapy. The major histocompatibility complex class II (MHC II) genes were studied in both groups of patients and phenotypes associated typically with them were observed. Hence, in 33 patients, two different pathogenic autoantibodies were detected simultaneously. The authors provide a computer model to show that each MHC II gene has relevant epitopes that recognize the antigens associated with both diseases. Using the databases in these computer models, the authors present the hypothesis that these two autoantibodies are produced simultaneously due to the phenomena of epitope spreading.

[Pemphigoid gestationis]

Pemphigoid gestationis (PG) is a rare autoimmune bullous dermatosis associated with pregnancy. Its previous designation, herpes gestationis, is obsolete. PG is characterized by a subepidermic separation induced by the presence of peripheral blood autoantibodies against two hemidesmosomal antigens: BPAG1 and BPAG2. Clinical diagnosis is confirmed by histology and positive cutaneous immunofluorescence tests. The most discriminant examination for other pruritic dermatoses of pregnancy is the enzyme-linked immunosorbent assay (Elisa) NC16A BP 180. First-line treatment is local corticosteroid therapy; if local treatment fails, general corticosteroid therapy should be administered. The prognosis is good for mother and child, except that there is a risk of preterm delivery and of moderate fetal growth restriction. Management in a specialized setting is therefore necessary. Recurrence is possible during subsequent pregnancies.

IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis

BACKGROUND

Patients with bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and pemphigoid gestationis (PG) have IgG antibodies against BP180 and BP230, components of the hemidesmosomes. Patients with linear IgA bullous dermatosis (LABD) have IgA autoantibodies against a 97/120-kDa protein which is highly homologous to a shedded fragment of the BP180-ectodomain.

OBJECTIVES

The aim of our study was to determine the incidence of IgA autoantibodies directed against BP180/BP230 in the pemphigoids and LABD and to determine the antigenic regions that are targeted by IgA autoantibodies.

METHODS

Utilizing baculovirus-expressed recombinant BP180 and BP230 proteins, we performed immunoblot analyses for IgA reactivity of sera from patients with BP (n = 30), MMP (n = 10), PG (n = 6), LABD (n = 6) and from control patients with non-related pruritic dermatoses (n = 8).

RESULTS

IgA reactivity against BP180 and/or BP230 was detected in 19/30 of the BP, in 7/10 of the MMP, in 6/6 of the LABD and in 3/6 of the PG sera, respectively, but not in the control group. In all subgroups, the major antigenic site recognized by IgA antibodies was located within the NH(2)-terminus of the BP180-ectodomain, but only a minority of the sera showed also IgA reactivity against the BP180-NC16a-domain. IgA reactivity against the central domain of BP180 was more frequently seen than against its COOH-terminus. IgA against the COOH- and NH(2)-terminus of BP230, respectively, was detected in 6/30 of the BP, 1/10 of the MMP, 1/6 of the LABD and 0/8 control sera.

CONCLUSION

IgA reactivity against BP180 and/or BP230 is a common finding in the pemphigoids.

Serum anti-BPAG1 auto-antibody is a novel marker for human melanoma

Malignant melanoma is one of the most aggressive types of tumor. Because malignant melanoma is difficult to treat once it has metastasized, early detection and treatment are essential. The search for reliable biomarkers of early-stage melanoma, therefore, has received much attention. By using a novel method of screening tumor antigens and their auto-antibodies, we identified bullous pemphigoid antigen 1 (BPAG1) as a melanoma antigen recognized by its auto-antibody. BPAG1 is an auto-antigen in the skin disease bullous pemphigoid (BP) and anti-BPAG1 auto-antibodies are detectable in sera from BP patients and are used for BP diagnosis. However, BPAG1 has been viewed as predominantly a keratinocyte-associated protein and a relationship between BPAG1 expression and melanoma has not been previously reported. In the present study, we show that bpag1 is expressed in the mouse F10 melanoma cell line in vitro and F10 melanoma tumors in vivo and that BPAG1 is expressed in human melanoma cell lines (A375 and G361) and normal human melanocytes. Moreover, the levels of anti-BPAG1 auto-antibodies in the sera of melanoma patients were significantly higher than in the sera of healthy volunteers (p<0.01). Furthermore, anti-BPAG1 auto-antibodies were detected in melanoma patients at both early and advanced stages of disease. Here, we report anti-BPAG1 auto-antibodies as a promising marker for the diagnosis of melanoma, and we discuss the significance of the detection of such auto-antibodies in cancer biology and patients.

Serological studies in bullous pemphigoid: a literature review of antibody titers at presentation and in clinical remission

Bullous pemphigoid is associated with antibodies to a 230 kDa and a 180 kDa protein. In a literature review we investigated the role of auto-antibodies as detected by different serological assays. Nine reports containing data on 143 patients were analyzed. Pre-treatment data showed that indirect immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and immunoblotting offer an 82.2% or greater probability of being positive. At the end of the study period, all patients had clinically improved, whether or not they were on therapy. Auto-antibodies were present in 29% of patients evaluated by monkey esophagus immunofluorescence and 75% of those evaluated by human skin immunofluorescence. Positive titers were also reported in 67.6% of patients evaluated by ELISA. In 100% of patients in whom immunoblotting was performed the titers became negative. In 3 patients (5.3%) using human skin immunofluorescence and in one patient (1.4%) using ELISA the titers were increased at the end of the study period. The correlation between anti-basement membrane zone antibodies and the clinical course of bullous pemphigoid requires further and long-term studies.

Evaluation of a new ELISA assay for detection of BP230 autoantibodies in bullous pemphigoid

The diagnosis of bullous pemphigoid is based on clinical observations and on the presence of autoantibodies directed against proteins of the dermoepidermal junction. Human recombinant BP180 and BP230 peptides have been used to develop new quantitative enzyme immunoassays (EIA) for the detection of specific antibodies. This study evaluated the sensitivity and specificity of a new immunoassay for the detection of BP230 autoantibodies and clinical correlations. Serum samples were tested from patients with bullous pemphigoid, other skin diseases, and from healthy donors. Autoantibodies anti-BP230 and anti-BP180 were assayed using the EIA method. Diagnostic specificity for both tests was over 98%; diagnostic sensitivity was 90% and 60% for anti-BP180 and anti-BP230, respectively. IgG anti-BP180 titers exhibited a significant correlation with disease activity. No patient in remission was positive for anti-BP230. In conclusion, anti-BP180 and anti-BP230 assays are useful in the diagnosis of bullous pemphigoid and provide information on disease activity.

IgG autoantibody reactivity against bullous pemphigoid (BP) 180 and BP230 in elderly patients with pruritic dermatoses

BACKGROUND

Pruritic dermatoses of the elderly often pose a diagnostic and therapeutic challenge. Specifically, a prodromal phase of bullous pemphigoid (BP) has to be considered in patients with pruritic lesions of polymorphic appearance. These conditions frequently do not fulfil all the clinical, histological and immunopathological criteria for establishing the diagnosis of BP.

OBJECTIVES

To investigate IgG reactivity against the autoantigens of BP, BP180 and BP230, by enzyme-linked immunosorbent assay, in elderly patients affected with various pruritic disorders who had never experienced clinically apparent blisters.

METHODS

The sera of 15 elderly patients with pruritic disorders (group I) were tested for IgG reactivity against BP180 and BP230. Also included were 30 patients with full-blown BP (group II) and 25 age-matched patients with immediate-type allergic reactions (group III).

RESULTS

Thirty-three per cent of the patients with pruritic disorders (group I) showed IgG against BP230 and/or BP180: four of 15 patients had IgG against BP230 while two of the 15 group I patients were BP180 reactive. All the BP sera (group II) showed IgG reactivity against BP180 and/or BP230. Notably, two of 25 control sera (group III) showed IgG reactivity against either BP180 or BP230.

CONCLUSIONS

The present findings suggest that IgG reactivity against BP230 (i.e. the COOH terminus), and to a lesser extent against BP180, is a common finding in pruritic disorders of the elderly with a wide clinical spectrum. IgG-mediated autoimmunity against the intracellular BP230 may facilitate a chronic, inflammatory response eventually leading to full-blown BP which is presumably associated with IgG against BP180.

Nikolsky's sign on the gingival mucosa: a clinical tool for oral health practitioners

BACKGROUND

Nikolsky's sign is a clinical sign which is elicited by a horizontal, tangential pressure to the mucosa and/or skin resulting in blisters extending and separating or peeling away. Few data are currently available in the literature about its usefulness, specificity, and sensitivity in the diagnosis of either oropharyngeal or cutaneous bullous diseases. The purpose of this study was to determine the sensitivity and specificity of the gingival Nikolsky's sign in the identification of an autoimmune blistering disease.

METHODS

Over a period of 13 years, we recruited 566 patients with autoimmune oral bullous and non-bullous diseases who possessed either maxillary or mandibular gingival mucosal lesions. All patients were subjected to a test causing a gingival Nikolsky's sign at their first visit during the diagnostic algorithm and in the active disease phase before commencing treatment.

RESULTS

A total of 566 patients (184 with and 382 without bullous lesions) had at least gingival involvement. A positive gingival Nikolsky's sign resulted in 100 (17.7%) of 566 patients: 86 patients with bullous lesions (53 with pemphigus vulgaris, eight with mucous membrane pemphigoid, 22 with bullous/mixed lichenoid lesions, and three with erythema multiforme) and 14 with non-bullous lesions (12 with non-bullous lichenoid lesions and two with systemic lupus erythematous/mixed connective tissue disease). Thus, the specificity of Nikolsky's sign was higher (96.3%) than the sensitivity (46.7%).

CONCLUSION

The results of this study support the use of Nikolsky's sign of the gingival mucosa as a viable test to establish the presence of oral bullous diseases.

Detection of anti-BP180NC16a and anti-BP230 autoantibodies in blister fluid of patients with bullous pemphigoid: the first survey in Greece

Bullous pemphigoid (BP) is an acquired bullous disease with an increasing prevalence among elderly people worldwide, including in Greece. Blister formation in most patients with BP is caused by autoantibodies against structural components of the basement membrane zone of the skin, predominantly BP180NC16a and BP230 antigens on the hemidesmosome adhesion complex. Routine diagnostic methods such as histological examination and direct and indirect immunofluorescence are combined to determine diagnosis. In this study, an ELISA was used to measure levels of both anti-BP180NC16A and anti-BP230 autoantibodies in the blister fluid of 13 patients with newly diagnosed BP, before starting treatment. The aim of the study was to evaluate this method as a diagnostic tool in BP. Our results indicate that blister-fluid examination by ELISA can be a useful tool to diagnose bullous pemphigoid, especially in elderly patients who refuse biopsy or have poor venous access.

Serum levels of IgE anti-BP180 and anti-BP230 autoantibodies in patients with bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is a subepidermal blistering disease characterized by autoantibodies against the hemidesmosomal proteins, BP180 and BP230. NC16A, a non-collagenous stretch of the BP180 ectodomain is the primary target of pathogenic IgG antibodies. Whereas IgG anti-BP180 autoantibodies play a primary role in the pathogenesis, there is a growing number of data regarding the potential pathogenic roles of IgE class autoantibodies in BP.

OBJECTIVES

To examine the levels of IgG and IgE autoantibodies against BP180 and BP230, and to investigate mutual association and clinical relevance.

METHODS

Sera obtained from 67BP patients and 36 healthy donors were subjected to ELISA assays to measure serum IgG and IgE levels of anti-BP180 and anti-BP230 antibodies.

RESULTS

IgG anti-BP180 antibodies were positive in 63 (94%) of 67BP patients. IgG anti-BP230, IgE anti-BP180, and IgE anti-BP230 antibodies were found in 48 (72%), 20 (30%) and 45 (67%), respectively. IgG anti-BP180 levels were correlated with the affected areas. IgG anti-BP230 antibodies tended to increase in proportion to elongation of disease duration. IgE anti-BP230 levels showed a strong association with local eosinophil accumulation, while the levels were reversely related with the affected areas in BP.

CONCLUSIONS

IgE autoantibodies to BP180 and BP230 are detected at high frequencies in BP. IgE anti-BP230 antibodies may have a role in attracting eosinophils to the skin lesions.

Dystonin/Bpag1--a link to what?

The dystonin/Bpag1 cytoskeletal interacting proteins play important roles in maintaining cytoarchitecture integrity in skin and in the neuromuscular system. The most profound phenotype observed in the dystonin mutant dystonia musculorum (dt) mice is a severe movement disorder, attributed in large part to sensory neuron degeneration. The molecular basis for this phenotype is currently not clear, despite several studies indicating possible causes for the pathology in dt mice. Complicating the picture of what essential dystonin functions are lost in dt mice is the fact that our understanding of the very nature of what dystonin is has evolved greatly over the past decade. Elucidating the roles of dystonin most relevant to neuronal function and survival should help to shed light on some of the common mechanisms underlying neurodegeneration.

Conditional targeting of plectin in prenatal and adult mouse stratified epithelia causes keratinocyte fragility and lesional epidermal barrier defects

Plectin, a widespread intermediate filament-based cytolinker protein capable of interacting with a variety of cytoskeletal structures and plasma membrane-bound junctional complexes, serves essential functions in maintenance of cell and tissue cytoarchitecture. We have generated a mouse line bearing floxed plectin alleles and conditionally deleted plectin in stratified epithelia. This strategy enabled us to study the consequences of plectin deficiency in this particular type of tissues in the context of the whole organism without plectin loss affecting other tissues. Conditional knockout mice died early after birth, showing signs of starvation and growth retardation. Blistering was observed on their extremities and on the oral epithelium after initial nursing, impairing food uptake. Knockout epidermis was very fragile and showed focal epidermal barrier defects caused by the presence of small skin lesions. Stratification, proliferation and differentiation of knockout skin seemed unaffected by epidermis-restricted plectin deficiency. In an additionally generated mouse model, tamoxifen-induced Cre-ER(T)-mediated recombination led to mice with a mosaic plectin deletion pattern in adult epidermis, combined with microblister formation and epidermal barrier defects. Our study explains the early lethality of plectin-deficient mice and provides a model to ablate plectin in adult animals which could be used for developing gene or pharmacological therapies.

Herpes gestationis in a mother and newborn: immunoclinical perspectives based on a weekly follow-up of the enzyme-linked immunosorbent assay index of a bullous pemphigoid antigen noncollagenous domain

BACKGROUND

Herpes gestationis (HG) is a rare, autoimmune, bullous disease that occurs during the second or third trimester and usually resolves over weeks or months after delivery. Neonates with HG are rare (estimated at 1 per 100,000 cases). Although anti-180-kDa bullous pemphigoid (BP180) autoantibody and transfer of this autoantibody are known as the cause, to our knowledge, no coordinated analysis of clinical symptoms and anti-BP180 antibody enzyme-linked immunosorbent assay titers has been reported in a mother and neonate with HG.

OBSERVATIONS

We describe a 33-year-old woman with HG and her neonate with vesicular erythematous lesions and the weekly follow-up results of the BP180 noncollagenous domain (NC16a) enzyme-linked immunosorbent assay.

CONCLUSIONS

Almost the same titer of pathogenic antibody as that in the mother is transferred to the neonate. The plasma elimination half-life of anti-BP180 antibody is approximately 15 days in mother and neonate. An abrupt twin peak increase in the BP180 enzyme-linked immunosorbent assay index from maternal serum was observed just before and after delivery, possibly explaining why HG usually occurs in the last trimester of pregnancy and exacerbates postpartum. Lesions in the neonate resolve without treatment far before pathogenic antibody disappears, suggesting that factors other than anti-BP180 antibodies may be involved in the generation of eruptions. Frequent testing of the BP180 enzyme-linked immunosorbent assay greatly facilitates therapeutic planning.

14-3-3 sigma isoform interacts with the cytoplasmic domain of the transmembrane BP180 in keratinocytes

The protein bullous pemphigoid antigen-2 (BPAG2/BP180/collagen type XVII) plays a key role in attachment of basal keratinocytes to epidermal basement membrane. The binding of BP180 with either integrin alpha6, integrin beta4, or bullous pemphigoid antigen-1 (BPAG1/BP230) is critical for this attachment in skin. The protein 14-3-3 sigma, also known as stratifin and a marker for epithelial cells, is a member of a highly conserved small acidic 14-3-3 protein family naturally found in all eukaryotic cells. Here, we have used a 14-3-3sigma GST pull-down screening assay and showed that sigma (sigma) isoform of the 14-3-3 protein family interacts with the cytoplasmic N-terminal domain of BP180. Analysis of a series of truncated or deleted 14-3-3sigma revealed that only intact 14-3-3sigma molecule, but not any of its fragments can interact with BP180. This finding suggests that conformation and possible dimerization of 14-3-3 sigma is essential for this interaction. Further, a BP180 co-immunoprecipitation (IP) and its reverse IP assays were conducted and the results confirmed that 14-3-3 sigma interacts with cytoplasmic domain, but not ecto-domain of the BP180. In conclusion, the finding of this study provides evidence that 14-3-3sigma isoform interacts with BP180 which is a major component of hemidesmosome involved in the attachment of epidermis to the basement membrane in skin. However, the significance of this interaction in hemidesmosome formation and/or attachment needs to be explored.

Effects of cyclosporine on transplant tolerance: the role of IL-2

Allograft(dagger) transplant outcome, rejection or tolerance, depends upon striking a balance between the pertinent cytopathic and regulatory T cells. The drug cyclosporine is a widely used immunosuppressive agent among transplant recipients. Previous studies have demonstrated that cyclosporine blocks apoptosis of activated T cells and the ability of costimulation blockade based regimens to create peripheral transplant tolerance. We now test the hypothesis that the mechanism by which cyclosporine blocks tolerance induction is IL-2 dependent, and linked to a detrimental effect upon T(reg) function. Our study demonstrates that cyclosporine blocks IL-2 gene expression and activation induced cell death (AICD) of alloreactive T effector cells. We also show that cyclosporine abolishes the beneficial effects of a donor specific transfusion (DST) plus anti-CD154 monoclonal antibody (alpha CD154) regimen on enhanced T(regs) function and allograft tolerance induction. Interestingly, provision of IL-2/Fc, a long-lived form of IL-2, completely reverses the detrimental effects of this adjunctive cyclosporine treatment on AICD of alloreactive T effectors, T(regs) function and tolerance induction. Furthermore, in a MHC mismatched islet allograft model, the combination of cyclosporine with IL-2/Fc permitted long-term allograft survival and induced alloantigen specific allograft tolerance. The combination of IL-2/Fc and cyclosporine treatment may provide a new clinical strategy to promote transplant tolerance.

Plakins in development and disease

Plakins are large multi-domain molecules that have various functions to link cytoskeletal elements together and to connect them to junctional complexes. Plakins were first identified in epithelial cells where they were found to connect the intermediate filaments to desmosomes and hemidesmosomes [Ruhrberg, C., and Watt, F.M. (1997). The plakin family: versatile organizers of cytoskeletal architecture. Curr Opin Genet Dev 7, 392-397.]. They were subsequently found to be important for the integrity of muscle cells. Most recently, they have been found in the nervous system, where their functions appear to be more complex, including cross-linking of microtubules (MTs) and actin filaments [Leung, C.L., Zheng, M., Prater, S.M., and Liem, R.K. (2001). The BPAG1 locus: Alternative splicing produces multiple isoforms with distinct cytoskeletal linker domains, including predominant isoforms in neurons and muscles. J Cell Biol 154, 691-697., Leung, C.L., Sun, D., Zheng, M., Knowles, D.R., and Liem, R.K. (1999). Microtubule actin cross-linking factor (MACF): a hybrid of dystonin and dystrophin that can interact with the actin and microtubule cytoskeletons. J Cell Biol 147, 1275-1286.]. These plakins have also indicated their relationship to the spectrin superfamily of proteins and the plakins appear to be evolutionarily related to the spectrins, but have diverged to perform different specialized functions. In invertebrates, a single plakin is present in both Drosophila melanogaster and Caenorhabditis elegans, which resemble the more complex plakins found in mammals [Roper, K., Gregory, S.L., and Brown, N.H. (2002). The 'spectraplakins': cytoskeletal giants with characteristics of both spectrin and plakin families. J Cell Sci 115, 4215-4225.]. In contrast, there are seven plakins found in mammals and most of them have alternatively spliced forms leading to a very complex group of proteins with potential tissue specific functions [Jefferson, J.J., Leung, C.L., and Liem, R.K. (2004). Plakins: goliaths that link cell junctions and the cytoskeleton. Nat Rev Mol Cell Biol 5, 542-553.]. In this review, we will first describe the plakins, desmoplakin, plectin, envoplakin and periplakin and then describe two other mammalian plakins, Bullous pemphigoid antigen 1 (BPAG1) and microtubule actin cross-linking factor 1 (MACF1), that are expressed in multiple isoforms in different tissues. We will also describe the relationship of these two proteins to the invertebrate plakins, shortstop (shot) in Drosophila and VAB-10 in C. elegans. Finally, we will describe an unusual mammalian plakin, called epiplakin.

IgE basement membrane zone antibodies induce eosinophil infiltration and histological blisters in engrafted human skin on SCID mice

Bullous pemphigoid (BP) is characterized by the deposition of IgG in the basement membrane zone, infiltration of eosinophils, and blister formation. The purpose of this study was to evaluate a potential role of IgE basement membrane antibodies in the histological findings of BP. LABD97 is a component of the shed ectodomain of bullous pemphigoid antigen 2. We have developed an IgE hybridoma to LABD97 antigen. This hybridoma was injected subcutaneously in SCID mice with engrafted human skin. A subcutaneous hybridoma secreting IgE antibodies developed. An IgE mouse hybridoma to trinitrophenyl was used as a control. Human grafts and mouse skin were examined grossly over 21 days, histologically, and immunopathologically at day 21 after injection of the hybridoma. A visible subcutaneous tumor developed in 10-14 days. Erythema and intense scratching developed 2-3 days before the tumor in test mice, but not in controls. At day 21, 16/16 test mice developed intense eosinophil infiltration and degranulation of the human mast cells within the grafts and 13/16 developed histological, but not clinically visible, basement membrane blisters. Human skin grafts of control mice and normal mouse skin on the test mice and control mice did not develop any histological abnormalities. IgE antibodies to LABD97 recapitulate the histological inflammatory process seen in BP.

Molecular characterization of the genetic lesion in Dystonia musculorum (dt-Alb) mice

Dystonia musculorum (dt) is an inherited autosomal recessive neuropathy in mice. Homozygous animals display primarily sensory neurodegeneration resulting in a severe loss of coordination. Several dt strains exist, including spontaneous mutants dt-Alb (Albany), dt-J (Jackson Labs), and dt-Frk (Frankel), and a transgene insertion mutant, Tg4. They contain mutations in the gene encoding Bullous Pemphigoid Antigen 1 (BPAG1), or dystonin. BPAG1 is a member of the plakin family of cytolinker proteins. BPAG1 is alternatively spliced to produce several isoforms, including the major brain-specific isoform, BPAG1a. The neurological phenotype observed in dt-Alb mice is thought to result from the absence of BPAG1a protein in the developing nervous system. The goal of this study was to determine the precise molecular nature of the dt-Alb mutation and examine residual BPAG1 expression in homozygous dt-Alb mice. A combination of molecular biological strategies revealed that the dt-Alb lesion is a deletion-insertion eliminating a large part of the coding region of BPAG1a. The molecular lesion in the dt-Alb BPAG1 allele is expected to render it completely non-functional. Although transcripts corresponding to BPAG1 segments still remaining in homozygous dt-Alb mice could be detected by RT-PCR, there was no positive signal for BPAG1 in the brain of dt-Alb mice by Northern blotting. Western blotting with polyclonal anti-BPAG1 antibodies confirmed the absence of functional BPAG1 protein (full-length or truncated) in the dt-Alb brain. Our identification of the 5' junction of the dt-Alb insertion makes it possible to genotype dt-Alb animals by standard PCR.

Retrolinkin, a membrane protein, plays an important role in retrograde axonal transport

Retrograde axonal transport plays an important role in the maintenance of neuronal functions, but the mechanism is poorly defined partly because the constituents of the retrograde transport system and their interactions have yet to be elucidated. Of special interest is how dynein/dynactin motor proteins interact with membrane cargoes. Here, we report that an endosomal vesicle protein, termed retrolinkin, functions as a receptor tethering vesicles to dynein/dynactin through BPAG1n4. Retrolinkin, a membrane protein highly enriched in neuronal endosomes, binds directly to BPAG1n4. Deletion of retrolinkin membrane-association domains disrupts retrograde vesicular transport, recapitulating the BPAG1 null phenotype. We propose that retrolinkin acts with BPAG1n4 to specifically regulate retrograde axonal transport. Our work lays the foundation for understanding fundamental issues of axonal transport and provides insights into the molecular mechanisms underlying human neurodegenerative disorders.

Vesicular pemphigoid with circulating autoantibodies against 230-kDa and 180-kDa proteins, and additional autoantibodies against 97-kDa and 45-kDa proteins

The vesicular variant of bullous pemphigoid is a clinical entity in which the principal type of lesions are multiple small tense vesicles in a symmetric distribution, instead of the classical large, more randomly distributed large bullae. We describe a 62-year-old female who developed a vesicular variant of bullous pemphigoid, with intensely pruritic vesiculopapular eruptions and erythematous irregularly outlined patches confluent on the face, neck, trunk, extremities and oral mucosa. Direct immunofluorescence revealed a linear deposition of IgG and C3 at the basement membrane zone of the skin, and indirect immunofluorescence detected circulating IgG autoantibodies reacting with antigens located on the epidermal side of skin split with 1 M NaCl. Indirect immunogold electron microscopy revealed IgG deposition at the underneath membrane of the basal cells and in the lamina lucida. In addition to the 230-kDa and 180-kDa bullous pemphigoid antigen, immunoblot analysis also demonstrated the presence of IgG antibodies reactive with 97-kDa and 45-kDa protein. Treatment with systemic corticosteroid, minocycline and antihistamines plus topical steroid resulted in moderate improvement. A few vesicles, however, continued to appear intermittently during the past year of treatment.