Anti-epiligrin cicatricial pemphigoid with IgG autoantibodies to the beta and gamma subunits of laminin 5

Autoimmunity against laminins

Laminins are ubiquitous constituents of the basement membranes with major architectural and functional role as supported by the fact that absence or mutations of laminins lead to either lethal or severely impairing phenotypes. Besides genetic defects, laminins are involved in a wide range of human diseases including cancer, infections, and inflammatory diseases, as well as autoimmune disorders. A growing body of evidence implicates several laminin chains as autoantigens in blistering skin diseases, collagenoses, vasculitis, or post-infectious autoimmunity. The current paper reviews the existing knowledge on autoimmunity against laminins referring to both experimental and clinical data, and on therapeutic implications of anti-laminin antibodies. Further investigation of relevant laminin epitopes in pathogenic autoimmunity would facilitate the development of appropriate diagnostic tools for thorough characterization of patients' antibody specificities and should decisively contribute to designing more specific therapeutic interventions.

Outcomes of cataract surgery in ocular cicatricial pemphigoid

PURPOSE

To report the outcomes of cataract surgery in ocular cicatricial pemphigoid (OCP).

SETTING

L. V. Prasad Eye Institute, Hyderabad, India.

DESIGN

Retrospective, interventional case series.

METHODS

Patients diagnosed with OCP who had undergone cataract surgery were included. Staging of disease, type of surgery, pre- and postoperative best-corrected visual acuity (BCVA), and number and duration of topical and systemic medications were recorded. Complications and any exacerbation or worsening of disease were noted.

RESULTS

Nine eyes of 7 patients (3 male, 4 female) were included in the study, with mean age of 60.44 ± 2.6 years (range 56-64 years). Follow-up ranged from 6 months to 10 years (mean 52.9 ± 46.25 months). Surgery performed was extracapsular cataract extraction with posterior chamber intraocular lens implantation (n = 5) or phacoemulsification with posterior chamber intraocular lens implantation (n = 4). Best-corrected visual acuity improved by more than 2 lines in 6 of 9 (66.67%) eyes, which remained stable till the last follow-up. Three eyes had no visual improvement due to corneal scar in 2 patients and preexisting posterior staphyloma in 1 eye. Disease progression was noted in 2 of 9 operated eyes by one stage at the end of 1 year.

CONCLUSION

In this series, cataract surgery could be safely performed with no major intra- or postoperative complications. While the surgical intervention itself was not associated with acute exacerbations of inflammation, progression of disease was noted in some cases over time. In spite of ongoing disease, cataract surgery in OCP was associated with stable visual outcomes.

Differences in basement membrane zone components of normal conjunctiva, conjunctiva in glaucoma and normal skin

PURPOSE

To describe the distribution of basement membrane zone (BMZ) components in normal conjunctiva, conjunctiva of patients with glaucoma and normal skin.

METHODS

Thirty-five normal conjunctival biopsies and 16 conjunctival biopsies of patients with glaucoma under topical anti-glaucomatous therapy were examined by immunohistochemistry. Antibodies were directed against laminin α chains, laminin subchains α1, α2, α3, β1, β3, γ1, γ2, γ3, kalinin, β4-integrin, and collagens IV and VII. Results were compared to the antigen distribution at the BMZ in normal skin.

RESULTS

The BMZ of skin stained positive for all antibodies tested. In contrast to skin, the BMZ of normal conjunctiva was negative for laminin subunits α2, β1, β3, γ2 and γ3 in most or all specimens. Positive findings at the conjunctival BMZ of patients with glaucoma were comparable to normal conjunctiva for laminin α, α1, β3, γ1, γ3, laminin 5, β4-integrin, collagen IV and collagen VII. However, staining of the BMZ with antibodies to laminin β1 (p=0.002) and γ2 (p=0.017) was seen in a significantly higher rate in glaucoma compared to controls.

CONCLUSION

Characteristic differences exist in the antigenicity of the BMZ in normal skin, normal conjunctiva and conjunctiva from patients with glaucoma, especially for laminin subchains. These differences may explain the variable ocular involvement in diseases of the BMZ. Moreover, they may explain the susceptibility of patients with glaucoma to develop mucous membrane pemphigoid-like disease. Alterations in conjunctival BMZ in glaucoma may be induced by long-term topical anti-glaucoma medications including various preservation agents.

Immunofluorescence serration pattern analysis as a diagnostic criterion in antilaminin-332 mucous membrane pemphigoid: immunopathological findings and clinical experience in 10 Dutch patients

BACKGROUND

Antilaminin-332 mucous membrane pemphigoid (anti-LN-332 MMP) is a chronic subepidermal blistering disease characterized by IgG anti-epidermal basement membrane zone (BMZ) autoantibodies against laminin-332 (LN-332).

PATIENTS

with anti-LN-332 MMP have an increased relative risk of malignancy. Laboratory techniques that are difficult to obtain are needed for diagnosis of anti-LN-332 MMP. Objectives  To incorporate direct immunofluorescence (DIF) serration pattern analysis of IgG depositions in the diagnostic criteria of anti-LN-332 MMP.

METHODS

Patients who met our revised inclusion criteria for anti-LN-332 MMP were selected from our biobank over the period 1997-2009. Inclusion criteria were clinical symptoms, DIF serration pattern analysis, indirect immunofluorescence (IIF) on salt-split skin, and antigen-specificity analysis of the serum including immunoblotting and/or immunoprecipitation and/or enzyme-linked immunosorbent assay (ELISA) against native LN-332.

RESULTS

Ten patients met the inclusion criteria. A malignancy was found in two patients (20%). In all patients in whom it was performed (n = 9), DIF showed linear IgG deposition along the BMZ in an n-serrated pattern. Nine sera reacted by salt-split skin analysis and bound to the dermal side of the split skin. ELISA against native LN-332 was positive in 78% of the tested sera.

CONCLUSIONS

Anti-LN-332 MMP can clinically resemble other forms of pemphigoid. Although state-of-the-art laboratory diagnostics are necessary for definite diagnosis, the combination of simple DIF serration pattern and IIF salt-split skin analysis will exclude other forms of MMP and epidermolysis bullosa acquisita from the differential diagnosis. Because of the increased risk for malignancy patients should be thoroughly oncologically screened.

Histopathology of anti-laminin 5 mucous membrane pemphigoid

BACKGROUND

Anti-laminin 5 mucous membrane pemphigoid (MMP) is an autoimmune blistering disease characterized by autoantibodies against the major basement membrane component laminin 5 (laminin 332, epiligrin).

OBJECTIVE AND METHODS

We reviewed 17 biopsy specimens from 9 patients with anti-laminin 5 MMP in an attempt to define typical histopathologic features of the disease.

RESULTS

Fifteen specimens showed subepidermal blister formation, while two biopsy specimens revealed an epithelial ulcer. In 11 biopsies a sparse to moderate inflammatory infiltrate composed of lymphocytes and neutrophils with some eosinophils was observed. Four biopsies showed a dense infiltrate dominated by neutrophils in two cases and by eosinophils in one case. The remaining biopsy revealed a dense lymphoplasmacellular infiltrate without granulocytes. Scarring of the upper dermis was present only in 5 specimens. Immunohistochemical analysis localized type IV collagen to the dermal side of the blister, suggesting that split formation occurred within the lamina lucida of the cutaneous basement membrane.

LIMITATIONS

The number of patients studied was relatively small.

CONCLUSIONS

Histopathology of anti-laminin 5 MMP is characterized by subepidermal blistering and a sparse to moderate superficial lymphohistiocytic infiltrate with neutrophils and/or eosinophils. Both infiltrate density and composition may vary, making anti-laminin 5 MMP indistinguishable from other autoimmune subepidermal blistering diseases by histopathology alone. Scarring is present only in a minority of cases and is not a sensitive clue to the diagnosis of anti-laminin 5 MMP.

Bullous pemphigoid positive for anti-BP180 and anti-laminin 5 antibodies in a patient with graft-vs-host disease

We report the case of a 55-year-old female with bullous pemphigoid (BP) who was positive for anti-BP180 and anti-laminin 5 antibodies after development of graft-vs-host disease (GVHD) caused by a bone marrow transplant. She had tense blisters on her trunk and extremities. Histologic examination showed a subepidermal blister and marked lymphocytic infiltration, especially eosinophils. Direct immunofluorescence revealed a linear deposition of IgG on the base membrane zone. Indirect immunofluorescence on 1M NaCl split skin revealed a linear IgG deposition to both sides of the epidermal and the dermal layers. Immunoblot assays using human epidermal extracts and BP180 NC16a domain recombinant protein confirmed the presence of IgG antibodies against BP180 and recombinant BP180 NC16a domain protein. Furthermore, immunoblotting using laminin 5 purified from human keratinocyte extract as the substrate demonstrated reactivity against the gamma2 and beta3 subunits but not the alpha3 subunit of laminin 5. We diagnosed BP and treated her with prednisolone (40 mg/day). Both skin and oral lesions resolved without leaving scars on the bulla. Immune disturbance as well as destruction of basal epidermal cells and base membrane by GVHD may result in the induction of autoimmune blistering diseases with unusual clinical and laboratory manifestations.

Number III Mucous membrane pemphigoid

Mucous membrane pemphigoid (MMP) is a sub-epithelial vesiculobullous disorder. It is now quite evident that a number of sub-epithelial vesiculobullous disorders may produce similar clinical pictures, and also that a range of variants of MMP exist, with antibodies directed against various hemidesmosomal components or components of the epithelial basement membrane. The term immune-mediated sub-epithelial blistering diseases (IMSEBD) has therefore been used. Immunological differences may account for the significant differences in their clinical presentation and responses to therapy, but unfortunately data on this are few. The diagnosis and management of IMSEBD on clinical grounds alone is impossible and a full history, general, and oral examination, and biopsy with immunostaining are now invariably required, sometimes supplemented with other investigations. No single treatment regimen reliably controls all these disorders, and it is not known if the specific subsets of MMP will respond to different drugs. Currently, apart from improving oral hygiene, immunomodulatory-especially immunosuppressive-therapy is typically used to control oral lesions. The present paper reviews pemphigoid, describing the present understanding of this fascinating clinical phenotype, summarising the increasing number of subsets with sometimes-different natural histories and immunological features, and outlining current clinical practice.

Ocular cicatricial pemphigoid: pathogenesis, diagnosis and treatment

Understanding of ocular cicatricial pemphigoid (OCP) has changed dramatically over the last three decades. Progress in basic science research in mucous membrane pemphigoid has been instrumental in outlining the key immune processes that participate in the autoimmune response. Immunomodulatory therapy has provided an avenue for preserving vision and preventing potentially fatal consequences of systemic pemphigoid. In this chapter we focus attention on the immunologic basis for disease and treatment strategies. We propose an algorithmic approach to diagnosis and management of OCP.

A case of antiepiligrin cicatricial pemphigoid with nephrotic syndrome

We report a 71-year-old woman with antiepiligrin cicatricial pemphigoid associated with nephrotic syndrome. She presented with a six-month history of pruritic blisters over her trunk and legs. She also had episodes of recurrent painful oral erosions. A skin biopsy showed a subepidermal bulla, and a direct immunofluorescence (DIF) study revealed linear deposition of IgG and C3 at the basement membrane zone (BMZ). Indirect immunofluorescence (IIF) staining of 1 M NaCl-split skin demonstrated circulating IgG autoantibodies reactive with the dermal side. Immunoprecipitation studies of the patient's serum disclosed IgG autoantibodies directed against a set of polypeptides that corresponded to laminin 5 (beta 3 gamma 2). Based upon the long-standing edema of her legs and her hypoproteinemia, she was diagnosed with nephrotic syndrome. To our knowledge, the association of antiepiligrin cicatricial pemphigoid with nephrotic syndrome has not been reported previously.

Anti-epiligrin cicatricial pemphigoid: clinical findings, immunopathogenesis, and significant associations

We report the clinical and immunopathologic findings in a cohort of 35 patients with anti-epiligrin cicatricial pemphigoid (AECP). These patients have a mucosal predominant subepithelial blistering disease that is clinically indistinguishable from other forms of cicatricial pemphigoid. The mucosal surfaces of the mouth and eye are most commonly involved. The skin is also involved in most patients, but usually this is less severe than mucosal involvement. AECP is characterized by the binding of circulating IgG autoantibodies to the dermal side of 1M NaCl split human skin on indirect immunofluorescence microscopy. These IgG antibasement membrane autoantibodies target laminin 5, a heterotrimeric protein consisting of alpha3, beta3, and gamma2 subunits. IgG autoantibodies predominantly target the G domain within the alpha subunit. The presence of circulating IgG autoantibodies are specific for the diagnosis of AECP and are not seen in patients with other autoimmune blistering diseases or normal volunteers. Furthermore, we expand on data previously reported on the finding of an increased relative risk for solid cancer in patients with AECP, especially in the first year after blister onset. The majority of cancers documented in a cohort of 35 patients assembled over 12 years of study were adenocarcinomas that were at an advanced stage at their time of detection. This circumstance is thought to account for a high incidence of mortality among AECP patients who develop an associated cancer. AECP patients also demonstrate a significant risk for mortality as a consequence of treatment with systemic immunosuppressives. The current longitudinal study suggests that only a minority of AECP patients go into remission.

Laminin-5 is targeted by autoantibodies in feline mucous membrane (cicatricial) pemphigoid

In human and canine patients with mucous membrane (cicatricial) pemphigoid (MMP), circulating autoantibodies have been shown to target multiple epidermal basement membrane antigenic epitopes. These autoantigens include collagen XVII in humans and dogs, as well as laminin-5, laminin-6 or integrin alpha-6/beta-4 in human beings. The purpose of this study was to determine if autoantibodies targeted laminin-5 in a cat exhibiting clinical and microscopic lesions resembling those of MMP in humans. In this patient, an indirect immunofluorescence (IF) assay revealed circulating IgG and IgA autoantibodies that bound to the basement membrane zone on the dermal side of salt-split gingiva (titer 1:1000 for IgG and 1:50 for IgA). Immunoblotting, performed with affinity-purified human laminin-5, demonstrated that the autoantibodies bound the alpha-3 chain of this heterotrimer. These observations identify laminin-5 as one of the antigens recognized by circulating autoantibodies in this feline homologue of MMP in humans and dogs.

IgG autoantibodies in patients with anti-epiligrin cicatricial pemphigoid recognize the G domain of the laminin 5 alpha-subunit

Anti-epiligrin cicatricial pemphigoid (AECP) is a mucosal-predominant, subepithelial blistering disease characterized by IgG anti-basement membrane autoantibodies to laminin 5 (alpha3beta3gamma2). This and prior studies found that autoantibodies from most patients recognize the alpha-subunit of this laminin isoform. Accordingly, sera from 10 representative patients were tested against prokaryotic recombinants of this polypeptide in epitope mapping studies. cDNAs spanning the full length of the alpha-subunit were generated by PCR, directionally cloned into the pGEX-4T-3 vector, and expressed as glutathione-S-transferase fusion proteins of appropriate size and immunoreactivity. Sera from 9 of 10 AECP patients immunoblotted fusion proteins corresponding to subdomains G2, G3, G4, and G5 at the carboxyl terminus of the laminin 5 alpha-subunit. Serum from 1 patient (and that from normal volunteers) showed no reactivity to any fusion proteins; no sera bound recombinant glutathione-S-transferase alone. Immunoadsorption of patient sera with fusion proteins corresponding to the G domain substantially reduced basement membrane autoantibody titers. IgG from patients with this form of cicatricial pemphigoid recognize the portion of laminin 5 thought to play a key role in promoting keratinocyte adhesion to epidermal basement membrane.

Laminins and human disease

The laminin protein family has diverse tissue expression patterns and is involved in the pathology of a number of organs, including skin, muscle, and nerve. In the skin, laminins 5 and 6 contribute to dermal-epidermal cohesion, and mutations in the constituent chains result in the blistering phenotype observed in patients with junctional epidermolysis bullosa (JEB). Allelic heterogeneity is observed in patients with JEB: mutations that results in premature stop codons produce a more severe phenotype than do missense mutations. Gene therapy approaches are currently being studied in the treatment of this disease. A blistering phenotype is also observed in patients with acquired cicatricial pemphigoid (CP). Autoantibodies targeted against laminins 5 and 6 destabilize epithelial adhesion and are pathogenic. In muscle cells, laminin alpha 2 is a component of the bridge that links the actin cytoskeleton to the extracellular matrix. In patients with laminin alpha 2 mutations, the bridge is disrupted and mature muscle cells apoptose. Congenital muscular dystrophy (CMD) results. The role of laminin in diseases of the nervous system is less well defined, but the extracellular protein has been shown to serve an important role in peripheral nerve regeneration. The adhesive molecule influences neurite outgrowth, neural differentiation, and synapse formation. The broad spatial distribution of laminin gene products suggests that laminin may be involved in a number of diseases for which pathogenic mechanisms are still being unraveled.

IgG, IgA and IgE autoantibodies against the ectodomain of BP180 in patients with bullous and cicatricial pemphigoid and linear IgA bullous dermatosis

BACKGROUND

Bullous pemphigoid (BP), linear IgA bullous dermatosis (LABD) and cicatricial pemphigoid (CP) are clinically distinct autoimmune bullous skin diseases characterized by autoantibodies against components of the epidermal basement membrane. Like most patients with BP, a significant subgroup of patients with CP has circulating IgG specific for BP180, a transmembraneous protein of hemidesmosomes. Moreover, sera of patients with LABD contain IgA autoantibodies reactive with a 97/120-kDa protein, LABD antigen 1, which is highly homologous to the extracellular portion of BP180.

OBJECTIVES

We aimed to determine whether, in these diseases, autoantibody reactivity to BP180 is restricted to distinct immunoglobulin subtypes.

METHODS

Utilizing a baculovirus-encoded form of the ectodomain of BP180, sera from patients with BP (n = 10), CP (n = 9), LABD (n = 10) and normal human control sera (n = 10) were analysed by immunoblot for IgG, IgA and IgE reactivity against BP180.

RESULTS

All of 10 BP sera displayed IgG, IgA and IgE reactivity with BP180. Six and seven of nine CP sera, respectively, contained IgG and IgA autoantibodies reactive with BP180, but none of nine sera contained BP180-specific IgE. Nine of 10 LABD sera contained IgA, and six of 10 IgG, which was reactive with BP180, but none of 10 sera showed IgE reactivity to BP180.

CONCLUSIONS

The presence of IgG and IgA autoantibody responses to BP180 in patients with three clinically distinct autoimmune bullous diseases indicates that an autoimmune response to the same distinct adhesion protein may lead to different clinical manifestations. It is therefore conceivable that variable epitopes of BP180 are targeted by the different autoantibody isotypes, resulting in the distinct clinical pictures.

Autoantibodies against the processed ectodomain of collagen XVII (BPAG2, BP180) define a canine homologue of linear IgA disease of humans

Linear IgA disease (LAD) is an acquired autoimmune subepidermal blistering dermatosis that affects human children and adults. In contrast to bullous pemphigoid, in which autoantibodies recognize transmembrane type XVII collagen (BP180, BPAG2), LAD is associated with skin-fixed and circulating IgA autoantibodies that target LAD-1, the processed extracellular form of type XVII collagen. An immunologic homologue of LAD in humans was identified in two dogs according to the following criteria: 1) erosive, ulcerative, and crusted lesions seen on the face, in the oral cavity, and on the extremities, 2) dermoepidermal clefting present in the basement membrane lamina lucida without inflammation or with mild neutrophilic infiltration, 3) basement membrane-fixed IgG and/or IgA antibodies, and 4) circulating IgA and IgG autoantibodies that target the 120-kd soluble protein LAD-1. The present study establishes unequivocally the existence of a naturally occurring canine model of LAD of humans.

Remission of antiepiligrin (laminin-5) cicatricial pemphigoid after excision of gastric carcinoma

PURPOSE

To describe a case of antiepiligrin cicatricial pemphigoid with unusual ocular manifestations and its remission after surgical removal of gastric carcinoma.

METHODS

We describe a 61-year-old Japanese man with antiepiligrin cicatricial pemphigoid.

RESULTS

He presented with conjunctival injection and discharge preceded by a 6-month period of erosive lesions in the oral mucosa and the truncal skin. An advanced gastric carcinoma was found and his serum immunoprecipitated laminin-5. Despite topical treatment with betamethasone, ofloxacin, and artificial tear solutions, serious symblepharon along the Meibomian line developed with little shortening of the inferior conjunctival sac. Following radical gastrectomy, the ocular and cutaneous lesions turned completely quiet.

CONCLUSION

The present case differed from past cases by lacking inferior conjunctival sac shortening and by showing erosive lesions solely at the mucocutaneous junctions. The ocular involvement in this case correlated very well with the severity of gastric carcinoma.