Detection of laminin 5-specific auto-antibodies in mucous membrane and bullous pemphigoid sera by ELISA

Intravenous Ig Ameliorates Disease in a Murine Model of Anti-Laminin 332 Mucous Membrane Pemphigoid

Intravenous Ig (IVIg) is used to treat mucous membrane pemphigoid, although its therapeutic effectivity is not sufficiently supported by randomized controlled clinical trials, and its mode of action is only insufficiently understood. We have examined the effect of IVIg in a mouse model of anti-laminin 332 mucous membrane pemphigoid and found that IVIg ameliorates both cutaneous and mucosal inflammatory lesions. Our investigation into the modes of action of IVIg in mucous membrane pemphigoid indicated effective anti-inflammatory mechanisms beyond the enhanced degradation of IgG mediated through inhibition of the FcRn. Our results suggest that IVIg curbs the activation of neutrophils at several levels. This includes a direct, immediate inhibitory effect on neutrophil activation by immune complexes but not C5a, which blunts the release of ROS and leukotriene B4 from neutrophils. IVIg also suppresses the formation of neutrophil extracellular traps in response to calcium ion ionophore. In vivo treatment with IVIg altered the transcriptome of blood leukocytes and bone marrow neutrophils toward less proinflammatory phenotypes. Collectively, our results support the effectivity of IVIg in the treatment of mucous membrane pemphigoid and indicate that effects on neutrophils at multiple levels may significantly contribute to its therapeutic effects.

Autoimmunity against laminin 332

Laminin 332 is a heterotrimeric structural protein of the basal membrane zone (BMZ) of the skin and adjacent mucosal tissues. The importance of laminin 332 for the structural integrity of the BMZ is demonstrated by mutations in any of the three genes encoding for its three chains causing variants of junctional epidermolysis bullosa. Autoimmunity against laminin 332 is observed in mucous membrane pemphigoid (MMP) and in the rare patients with orf-induced pemphigoid. MMP is an autoimmune blistering disease with predominant mucosal manifestations and autoantibodies against the BMZ of the skin and orifice-close mucous membranes. The main autoantigens of MMP are type XVII collagen (BP180) and laminin 332 targeted in about 80% and 10-20% of patients, respectively. An increasing number of studies has highlighted the association of anti-laminin 332 MMP and malignancies that can be revealed in about a quarter of these patients. This data has led to the recommendation of current guidelines to assay for anti-laminin 332 reactivity in all MMP patients. The present review focuses on anti-laminin 332 MMP describing clinical features, its pathophysiology, and detection of serum anti-laminin 332 IgG. In addition, the available data about the occurrence of malignancies in anti-laminin 332 MMP, the underlying tumor entities, and its biology are detailed.

Case report: A case of anti-laminin 332 mucous membrane pemphigoid associated with severe pharyngolaryngeal involvement

A 74-year-old woman presented with a 30-day history of blisters and erosions in the oral cavity, trunk, and left eye conjunctival mucosa, also reporting a weight loss of 15 kg in the last 3 months. Histopathological examination showed subepidermal blisters and lymphocytic infiltrates with rare eosinophils in the superficial dermis. Direct immunofluorescence showed linear deposits of IgG and C3 along the dermal-epidermal junction and salt-split skin indirect immunofluorescence confirmed the presence of linear deposits of IgG along the blister floor. Indirect immunofluorescence revealed antibodies against laminin 332 using recombinant laminin 332 expressed in human HEK293 cells, and commercial ELISA kits (Euroimmun, Padova, Italy) did not reveal antibodies against BP230 and BP180 antigens. Anti-laminin 332 mucous membrane pemphigoid (MMP), a condition often associated with a hidden neoplasm, was diagnosed. In our case, the paraneoplastic nature of MMP was excluded. Thus, topical treatment with triamcinolone acetonide 0.1% in orabase once daily for 30 days, oral prednisone 0.75 mg/kg/day and rituximab were started to relieve symptoms. Conjunctival, nasal and oral erosions improved, as well as skin lesions, but later the patient was tracheotomized due to respiratory distress linked to the appearance of pharyngolaryngeal synechiae.

Mucous membrane pemphigoid

Mucous membrane pemphigoid (MMP) is a clinically and immunopathologically heterogenous disease with an incidence of about 2/million inhabitants/year in central Europe. Pemphigoid diseases are characterized by autoantibodies against structural proteins of the epidermis and/or surface-close epithelia. MMP has been defined as pemphigoid disease with predominant mucosal lesions. Most frequently, the oral cavity and the conjunctivae are affected. Lesions outside the mouth tend to heal with scarring leading to visual impairment and finally blindness, as well as, more rarely, impairment of breathing and food intake. Autoantibodies target BP180 (collagen type XVII), laminin 332, BP230 (nearly always in conjunction with other antigens), and type VII collagen in about 75%, 10-20%, 10-30%, and <5% of MMP patients, respectively. While the main autoantibody isotype is IgG, additional, and less frequently, exclusive IgA autoantibodies can be detected in the majority of patients. Assaying for anti-laminin 332 reactivity is pivotal, since in about a quarter of patients with anti-laminin 332 MMP, a malignancy, mainly solid cancers, is associated. The pathophysiology of MMP is yet incompletely understood. A recent mouse model of anti-laminin 332 MMP replicating characteristic clinical and immunopathological findings of the human disease may be helpful to close this knowledge gap. Diagnosis is established by the clinical picture with predominant mucosal lesions and visualization of tissue-bound anti-basement membrane zone antibodies by direct immunofluorescence microscopy. In recent S3 guidelines initiated by the European Academy of Dermatology and Venereology, the clinical spectrum and diagnostic strategies are detailed. In addition, treatment regimens for different clinical situations including patients with exclusive oral or ocular involvement are outlined. Future studies are needed to better understand the clinal complexity and associations as well as to establish widely available diagnostic assays and evidence-based therapeutic strategies.

Subunit-Specific Reactivity of Autoantibodies Against Laminin-332 Reveals Direct Inflammatory Mechanisms on Keratinocytes

Laminin-332 pemphigoid is a rare and severe autoimmune blistering disease, caused by IgG autoantibodies targeting laminin-332 in the dermal-epidermal basement zone. Laminin-332 pemphigoid is characterized by variable inflammatory infiltrate and the predominance of non-complement-fixing antibodies. Given these findings, we hypothesized that IgG autoantibodies to laminin-332 directly resulted in keratinocyte expression of inflammatory factors. We performed RNA-seq on primary human keratinocytes treated with IgG from patients with laminin-332 pemphigoid. Genes for numerous cytokines and chemokines were upregulated, including CSF2, CSF3, CXCL1, CXCL5, CXCL3, CXCL8, CXCL10, CXCL1, IL6, IL7, IL15, IL23, IL32, IL37, TGFB2 as well as metalloproteases. Considering the pro-inflammatory and proteolytic effect of autoantibodies from patients with laminin-332 pemphigoid identified in our initial experiment, we next questioned whether the reactivity against specific laminin subunits dictates the inflammatory and proteolytic keratinocyte response. Then, we treated keratinocytes with IgG from a separate cohort of patients with reactivity against individual subunits of laminin-332. We identified upregulation of IL-1α, IL-6, IL-8, CXCL1, MMP9, TSLP, and GM-CSF at the protein level, most notably in keratinocytes treated with IgG from laminin β3-reactive patients. We for the first time demonstrated a pro-inflammatory response, similar to that described in keratinocytes treated with IgG autoantibodies from patients with bullous pemphigoid, providing novel insight into the pathogenesis of laminin-332 pemphigoid and laminin-332 biology.

European Guidelines (S3) on diagnosis and management of mucous membrane pemphigoid, initiated by the European Academy of Dermatology and Venereology - Part II

This guideline has been initiated by the task force Autoimmune Blistering Diseases of the European Academy of Dermatology and Venereology, including physicians from all relevant disciplines and patient organizations. It is a S3 consensus-based guideline that systematically reviewed the literature on mucous membrane pemphigoid (MMP) in the MEDLINE and EMBASE databases until June 2019, with no limitations on language. While the first part of this guideline addressed methodology, as well as epidemiology, terminology, aetiology, clinical presentation and outcome measures in MMP, the second part presents the diagnostics and management of MMP. MMP should be suspected in cases with predominant mucosal lesions. Direct immunofluorescence microscopy to detect tissue-bound IgG, IgA and/or complement C3, combined with serological testing for circulating autoantibodies are recommended. In most patients, serum autoantibodies are present only in low levels and in variable proportions, depending on the clinical sites involved. Circulating autoantibodies are determined by indirect IF assays using tissue substrates, or ELISA using different recombinant forms of the target antigens or immunoblotting using different substrates. The major target antigen in MMP is type XVII collagen (BP180), although in 10-25% of patients laminin 332 is recognized. In 25-30% of MMP patients with anti-laminin 332 reactivity, malignancies have been associated. As first-line treatment of mild/moderate MMP, dapsone, methotrexate or tetracyclines and/or topical corticosteroids are recommended. For severe MMP, dapsone and oral or intravenous cyclophosphamide and/or oral corticosteroids are recommended as first-line regimens. Additional recommendations are given, tailored to treatment of single-site MMP such as oral, ocular, laryngeal, oesophageal and genital MMP, as well as the diagnosis of ocular MMP. Treatment recommendations are limited by the complete lack of high-quality randomized controlled trials.

Eosinophils, a Jack of All Trades in Immunity: Therapeutic Approaches for Correcting Their Functional Disorders

BACKGROUND AND OBJECTIVE

Eosinophils are primitive myeloid cells derived from bonemarrow precursors and require the intervention of interleukin (IL)-5 for their survival and persistence in blood and tissues. Under steady-state conditions, they contribute to immune regulation and homeostasis. Under pathological circumstances, eosinophils are involved in host protection against parasites and participate in allergy and inflammation.

DISCUSSION

Mostly, in asthma, eosinophils provoke airway damage via the release of granule contents and IL-13 with mucus hypersecretion and differentiation of goblet cells. Then, tissue remodeling follows with the secretion of transforming growth factor-β. Eosinophils are able to kill helminth larvae acting as antigen-presenting cells with the involvement of T helper (h)-2 cells and subsequent antibody response. However, they also exert pro-worm activity with the production of suppressive cytokine (IL- 10 and IL-4) and inhibition of nitric oxide. Eosinophils may play a pathogenic role in the course of chronic and autoimmune disease, e.g., inflammatory bowel disease and eosinophilic gastroenteritis, regulating Th2 responses and promoting a profibrotic effect. In atopic dermatitis, eosinophils are commonly detected and may be associated with disease severity. In cutaneous spontaneous urticaria, eosinophils participate in the formation of wheals, tissue remodeling and modifications of vascular permeability. With regard to tumor growth, it seems that IgE can exert anti-neoplastic surveillance via mast cell and eosinophil-mediated cytotoxicity, the so-called allergo-oncology. From a therapeutic point of view, monoclonal antibodies directed against IL-5 or the IL-5 receptors have been shown to be very effective in patients with severe asthma. Finally, as an alternative treatment, polyphenols for their anti-inflammatory and anti-allergic activities seem to be effective in reducing serum IgE and eosinophil count in bronchoalveolar lavage in murine asthma.

CONCLUSION

Eosinophils are cells endowed with multiple functions and their modulation with monoclonal antibodies and nutraceuticals may be effective in the treatment of chronic disease.

Diagnosis of autoimmune bullous diseases

Autoimmune bullous disorders (AIBDs) are a heterogeneous group of rare diseases clinically characterized by erosions and/or blisters on the skin and mucous membranes. AIBDs can be categorized into two groups: pemphigus diseases, characterized by intraepidermal blistering and autoantibodies against desmosomal proteins such as desmoglein (Dsg) 1, Dsg3, members of the plakin family, and subepidermal AIBDs, comprised of pemphigoid diseases and dermatitis herpetiformis. Autoantibodies in dermatitis herpetiformis target transglutaminases 2 and 3, while in pemphigoid disease, autoantibodies are directed against structural proteins of the dermal-epidermal junction. Although analysis of a perilesional biopsy with direct immunofluorescence (IF) microscopy is still the diagnostic gold standard, several assays have become widely available that allow serological diagnosis in the majority of patients. Standard serological diagnosis includes indirect IF on monkey esophagus and salt-split human skin. Assays to further characterize autoantibody specificity include ELISA systems based on recombinant forms of the immunodominant regions of the target antigens as well as multivariant indirect IF microscopy tests with several miniature substrates. These serological assays are complemented by various in-house assays using immunoblotting and ELISA, which are only available in specialized laboratories. Here we review new developments in the diagnosis of AIBDs and describe state-of-the-art diagnostic procedures for this group of diseases.

Advances in the diagnosis of autoimmune bullous dermatoses

Autoimmune bullous dermatoses are defined by autoantibodies directed against adhesion proteins in the epidermis or basement membrane zone, resulting in blister formation on the skin and mucosa. Diagnosis depends on lesional biopsy for histopathology and perilesional biopsy for direct immunofluorescence. Additional diagnostic methods include indirect immunofluorescence, enzyme-linked immunosorbent assay, and immunoblot (Western blot), which may be selected in specific clinical scenarios due to improved sensitivity and/or specificity. This contribution reviews the available evidence supporting the use of each method to provide a practical reference for clinicians when diagnosing autoimmune bullous disorders. Techniques and cost are reviewed, and newer diagnostic techniques with potential for clinical application are.

Laminin 511 is a target antigen in autoimmune pancreatitis

Autoimmune pancreatitis (AIP), a major manifestation of immunoglobulin G4-related disease (IgG4-RD), is an immune-mediated disorder, but the target autoantigens are still unknown. We previously reported that IgG in patients with AIP induces pancreatic injuries in mice by binding the extracellular matrix (ECM). In the current study, we identified an autoantibody against laminin 511-E8, a truncated laminin 511, one of the ECM proteins, in patients with AIP. Anti-laminin 511-E8 IgG was present in 26 of 51 AIP patients (51.0%), but only in 2 of 122 controls (1.6%), by enzyme-linked immunosorbent assay. Because truncated forms of other laminin family members in other organs have been reported, we confirmed that truncated forms of laminin 511 also exist in human and mouse pancreas. Histologic studies with patient pancreatic tissues showed colocalization of patient IgG and laminin 511. Immunization of mice with human laminin 511-E8 induced antibodies and pancreatic injury, fulfilling the pathologic criteria for human AIP. Four of 25 AIP patients without laminin 511-E8 antibodies had antibodies against integrin α6β1, a laminin 511 ligand. AIP patients with laminin 511-E8 antibodies exhibited distinctive clinical features, as the frequencies of malignancies or allergic diseases were significantly lower in patients with laminin 511-E8 antibodies than in those without. The discovery of these autoantibodies should aid in the understanding of AIP pathophysiology and possibly improve the diagnosis of AIP.

Diagnostik blasenbildender Autoimmundermatosen

Blasenbildende Autoimmundermatosen (BAIDs) sind eine heterogene Gruppe seltener Erkrankungen, die klinisch durch Erosionen und/oder Blasen an Haut und Schleimhäuten charakterisiert sind. BAIDs können in zwei Gruppen eingeteilt werden: Pemphigus-Erkrankungen, die durch intraepidermale Blasenbildung und Autoantikörper gegen desmosomale Proteine wie Desmoglein (Dsg) 1, Dsg3 und Mitglieder der Plakin-Familie charakterisiert sind, sowie subepidermale BAIDs, die Pemphigoid-Erkrankungen und die Dermatitis herpetiformis umfassen. Bei der Dermatitis herpetiformis greifen die Autoantikörper die Transglutaminasen 2 und 3 an, während sie bei Pemphigoid-Erkrankungen gegen Strukturproteine der dermoepidermalen Junktionszone gerichtet sind. Die Analyse einer periläsionalen Biopsie mittels direkter Immunfluoreszenzmikroskopie (IF-Mikroskopie) stellt zwar nach wie vor den diagnostischen Goldstandard dar, mittlerweile sind jedoch verschiedene Tests allgemein verfügbar, die eine serologische Diagnosefindung für den Großteil der Patienten ermöglichen. Zur serologischen Standarddiagnostik gehört die indirekte IF auf Affenösophagus und NaCl-separierter Spalthaut. Die Spezifität der Autoantikörper kann mit ELISA-Systemen, die auf rekombinanten Formen der immundominanten Regionen der Zielantigene basieren, sowie indirekter IF-Mikroskopie anhand multivarianter Tests mit mehreren multivariate näher charakterisiert werden. Diese serologischen Tests werden durch verschiedene hauseigene Immunoblotting- und ELISA-Systeme ergänzt, die nur in spezialisierten Laboratorien verfügbar sind. In diesem Review geben wir einen Überblick über neue Entwicklungen bei der Diagnose von BAIDs und beschreiben moderne Diagnoseverfahren für diese Krankheitsgruppe.

Serological Diagnosis of Autoimmune Bullous Skin Diseases

Autoimmune bullous dermatoses (AIBD) encompass a variety of organ-specific autoimmune diseases that manifest with cutaneous and/or mucosal blisters and erosions. They are characterized by autoantibodies targeting structural proteins of the skin, which are responsible for the intercellular contact between epidermal keratinocytes and for adhesion of the basal keratinocytes to the dermis. The autoantibodies disrupt the adhesive functions, leading to splitting and blister formation. In pemphigus diseases, blisters form intraepidermally, whereas in all other disease types they occur subepidermally. Early identification of autoimmune bullous dermatoses is crucial for both treatment and prognosis, particularly as regards tumor-associated disease entities. The diagnosis is based on clinical symptoms, histopathology, direct immunofluorescence to detect antibody/complement deposits, and the determination of circulating autoantibodies. The identification of various target antigens has paved the way for the recent development of numerous specific autoantibody tests. In particular, optimized designer antigens and multiplex test formats for indirect immunofluorescence and ELISA have enhanced and refined the laboratory analysis, enabling highly efficient serodiagnosis and follow-up. This review elaborates on the current standards in the serological diagnostics for autoimmune bullous dermatoses.

Keratinocyte footprint assay discriminates antilaminin-332 pemphigoid from all other forms of pemphigoid diseases

Background

Antilaminin‐332 mucous membrane pemphigoid is a chronic severe pemphigoid disease characterized by autoantibodies to laminin‐332. At present no commercial assay is available to demonstrate antilaminin‐332 antibodies, and diagnosis relies on in‐house techniques with limited sensitivities.

Objectives

In order to move, keratinocytes cultured in vitro secrete laminin‐332 to attach to the culture dish. In that way, they leave behind a unique footprint trail of laminin‐332. We aimed to develop a sensitive and specific laboratory assay to determine antilaminin‐332 autoantibodies in patient serum based on binding of patient IgG to these unique footprints.

Methods

Normal human keratinocytes were grown on glass coverslips and incubated with patient or control serum for 1 h. The binding of IgG was then investigated by immunofluorescence. After validating the test for its ability to identify antilaminin‐332 autoantibodies it was converted into a daily available test based on binding of IgG to dried coverslips that can be stored frozen. The staining patterns of sera from patients with antilaminin‐332 pemphigoid were then compared with those of sera from patients with other autoimmune bullous diseases and normal human sera.

Results

IgG of all antilaminin‐332 pemphigoid sera (n = 16) bound to laminin‐332 footprints, while all normal human controls (n = 55) were negative. From the sera of patients with other diseases (n = 72) four sera tested positive. The footprint assay was also positive for sera that were negative by salt‐split skin analysis, demonstrating that it is a very sensitive technique.

Conclusions

The keratinocyte footprint assay is a fast and specific assay to confirm or rule out the presence of antilaminin‐332 autoantibodies.

What's already known about this topic?

Antilaminin‐332 mucous membrane pemphigoid is a severe form of pemphigoid, and patients may have an increased risk of malignancies.

The diagnosis of antilaminin‐332 mucous membrane pemphigoid is complicated by the lack of specific commercial tests for antilaminin‐332 antibodies and can be confirmed only in specialized laboratories.

Keratinocytes in culture need laminin‐332 for adhesion and migration and therefore deposit it on the bottom of the culture dish.

What does this study add?

The keratinocyte footprint assay detects antilaminin‐332 autoantibodies in patient serum using the native laminin‐332 produced by cultured keratinocytes.

What is the translational message?

The keratinocyte footprint assay is a fast and specific assay to confirm or rule out the presence of antilaminin‐332 autoantibodies.

Linked Comment: https://doi.org/10.1111/bjd.18372.

https://doi.org/10.1111/bjd.18761 available online

A sensitive and specific assay for the serological diagnosis of antilaminin 332 mucous membrane pemphigoid

BACKGROUND

Antilaminin 332 mucous membrane pemphigoid (MMP) is an autoimmune subepidermal blistering disease with predominant mucosal involvement and autoantibodies against laminin 332. Malignancies have been associated with this disease; however, no standardized detection system for antilaminin 332 serum antibodies is widely available.

OBJECTIVES

Development of a sensitive and specific assay for the detection of antilaminin 332 antibodies.

METHODS

An indirect immunofluorescence (IF) assay using recombinant laminin 332 was developed and probed with a large number of antilaminin 332 MMP patient sera (n = 93), as well as sera from patients with antilaminin 332-negative MMP (n = 153), bullous pemphigoid (n = 20), pemphigus vulgaris (n = 20) and noninflammatory dermatoses (n = 22), and healthy blood donors (n = 100).

RESULTS

In the novel IF assay, sensitivities with the laminin 332 heterotrimer and the individual α3, β3 and γ2 chains were 77%, 43%, 41% and 13%, respectively, with specificities of 100% for each substrate. The sensitivity for the heterotrimer increased when an anti-IgG4 enriched antitotal IgG conjugate was applied. Antilaminin 332 reactivity paralleled disease activity and was associated with malignancies in 25% of patients with antilaminin 332 MMP.

CONCLUSIONS

The novel IF-based assay will facilitate the serological diagnosis of antilaminin 332 MMP and may help to identify patients at risk of a malignancy.

Diagnosis of Autoimmune Blistering Diseases

Autoimmune skin blistering diseases (AIBD) are characterized by autoantibodies that are directed against structural proteins in the skin and adjacent mucous membranes. Some clinical signs are typical for a specific AIBD, however, correct diagnosis requires the detection of tissue-bound or circulating autoantibodies. The gold standard for diagnosis of AIBD is the detection of autoantibodies or complement component 3 by direct immunofluorescence (DIF) microscopy of a perilesional biopsy. Circulating antibodies can be detected via indirect immunofluorescence (IIF) microscopy of different tissue substrates including human skin, monkey esophagus, and more recently, recombinant forms of the different target antigens. Latter are also employed in various commercial ELISA systems and by immunoblotting in in-house assays available in specialized laboratories. ELISA systems are also particularly valuable for monitoring of the disease activity during the disease course which can be helpful for treatment decisions. Exact diagnosis is essential for both treatment and prognosis, since some AIBD are associated with malign tumors such as paraneoplastic pemphigus and anti-laminin 332 mucous membrane pemphigoid. This review presents clinical and immunopathological features of AIBD for the state-of the art diagnosis of these disorders.

The spectrum of histopathologic findings in pemphigoid: Avoiding diagnostic pitfalls

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune vesiculobullous dermatitis that primarily affects the elderly and presents with tense, fluid-filled blisters. The histological hallmark on routine hematoxylin & eosin (H&E)-stained specimens is a subepidermal blister with luminal eosinophils. However, there are histologic variants than can produce diagnostic confusion.

METHODS

All immunofluorescence reports from an independent certified dermatopathology laboratory (2006-2015) were inspected, and those with findings consistent with an autoimmune subepidermal blistering process were selected. Seventy-seven cases were identified, and the corresponding H&E-stained specimens were reviewed by two dermatopathologists who tabulated the histopathologic findings.

RESULTS

Just over half of biopsies showed subepidermal clefting (54%). The histologic variants included: urticarial or eczematous findings (17%), partial or complete re-epithelialization (28%), and epidermal necrosis (7%).

CONCLUSION

While re-epithelialization of subepidermal blisters is a commonly accepted phenomenon, there are no published data demonstrating its incidence. Because only half of the biopsies showed the classic subepidermal blister, it is important to be aware of the spectrum of histopathologic findings that occur in this disease. Specifically, the presence of an intraepidermal blister and/or epidermal necrosis on routine H&E-stained specimens does not preclude the diagnosis of pemphigoid.

Molecular diagnosis of anti-laminin 332 (epiligrin) mucous membrane pemphigoid

BACKGROUND

Mucous membrane pemphigoid is a group of chronic subepithelial autoimmune blistering diseases that mainly affect mucous membranes. Laminin 332-specific autoantibodies are present in approximately 1/3 of the patients, being associated with an increased risk of malignancy. Because of the severe complications, an early recognition of the disease allowing a timely therapy is essential. The gold standard methods for detection of laminin 332-specific autoantibodies, including the immunoprecipitation and immunoblotting are non-quantitative, laborious and restricted to a few specialized laboratories worldwide. In addition, the use of radioimmunoassays, although highly sensitive and specific, are laborious, expensive and tightly regulated. Therefore, there is a stringent need for a quantitative immunoassay for the routine detection of laminin 332-specific autoantibodies more broadly available to diagnostic laboratories. The aim of this study was to compare different antigenic substrates, including native, recombinant laminin 332 and laminin 332-rich keratinocyte extracellular matrix, for development of an ELISA to detect autoantibodies in mucous membrane pemphigoid.

RESULTS

Using a relatively large number of sera from MMP patients with well-characterized autoantibody reactivity we show the suitability of ELISA systems using laminin 332 preparations as adjunct diagnostic tools in MMP. While glycosylation of laminin 332 does not appear to influence its recognition by MMP autoantibodies, ELISA systems using both purified, native and recombinant laminin 332 demonstrated a high sensitivity and good correlation with the detection of autoantibodies by immunoblotting. ELISA systems using different laminin 332 preparations represent a feasible and more accessible alternative for a broad range of laboratories.

CONCLUSIONS

Our findings qualify the use of immunoassays with the laminin 332-rich preparations as an ancillary diagnostic tool in mucous membrane pemphigoid.

Bullous pemphigoid. Сlinic, Diagnosis and Treatment

The article describes modern views on the predisposing factors, features, immunological changes and link with the histocompatibility antigens HLA, the role of circulating autoantibodies, cytokines, chemokines, matrix metalloproteinases and BP180 (BPAg2) и BP230 (BPAg1), those role in the pathogenesis of the bullous pemphigoid and their correlation with the activity of pathological process in patients with bullous pemphigoid. Described experimental model of the disease in animals, modern medications and methods of treatment of this disease.

Eosinophils in Autoimmune Diseases

Eosinophils are multifunctional granulocytes that contribute to initiation and modulation of inflammation. Their role in asthma and parasitic infections has long been recognized. Growing evidence now reveals a role for eosinophils in autoimmune diseases. In this review, we summarize the function of eosinophils in inflammatory bowel diseases, neuromyelitis optica, bullous pemphigoid, autoimmune myocarditis, primary biliary cirrhosis, eosinophilic granulomatosis with polyangiitis, and other autoimmune diseases. Clinical studies, eosinophil-targeted therapies, and experimental models have contributed to our understanding of the regulation and function of eosinophils in these diseases. By examining the role of eosinophils in autoimmune diseases of different organs, we can identify common pathogenic mechanisms. These include degranulation of cytotoxic granule proteins, induction of antibody-dependent cell-mediated cytotoxicity, release of proteases degrading extracellular matrix, immune modulation through cytokines, antigen presentation, and prothrombotic functions. The association of eosinophilic diseases with autoimmune diseases is also examined, showing a possible increase in autoimmune diseases in patients with eosinophilic esophagitis, hypereosinophilic syndrome, and non-allergic asthma. Finally, we summarize key future research needs.

Paraneoplastic Pemphigus and Autoimmune Blistering Diseases Associated with Neoplasm: Characteristics, Diagnosis, Associated Neoplasms, Proposed Pathogenesis, Treatment

Autoimmune paraneoplastic and neoplasm-associated skin syndromes are characterized by autoimmune-mediated cutaneous lesions in the presence of a neoplasm. The identification of these syndromes provides information about the underlying tumor, systemic symptoms, and debilitating complications. The recognition of these syndromes is particularly helpful in cases of skin lesions presenting as the first sign of the malignancy, and the underlying malignancy can be treated in a timely manner. Autoimmune paraneoplastic and neoplasm-associated bullous skin syndromes are characterized by blister formation due to an autoimmune response to components of the epidermis or basement membrane in the context of a neoplasm. The clinical manifestations, histopathology and immunopathology findings, target antigens, associated neoplasm, current diagnostic criteria, current understanding of pathogenesis, and treatment options for a selection of four diseases are reviewed. Paraneoplastic pemphigus manifests with clinically distinct painful mucosal erosions and polymorphic cutaneous lesions, and is often associated with lymphoproliferative neoplasm. In contrast, bullous pemphigoid associated with neoplasm presents with large tense subepidermal bullae of the skin, and mild mucosal involvement, but without unique clinical features. Mucous membrane pemphigoid associated with neoplasm is a disorder of chronic subepithelial blisters that evolve into erosions and ulcerations that heal with scarring, and involves stratified squamous mucosal surfaces. Linear IgA dermatosis associated with neoplasm is characterized by annularly grouped pruritic papules, vesicles, and bullae along the extensor surfaces of elbows, knees, and buttocks. Physicians should be aware that these autoimmune paraneoplastic and neoplasm-associated syndromes can manifest distinct or similar clinical features as compared with the non-neoplastic counterparts.

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.

Salivary IgA and IgG antibodies to bullous pemphigoid 180 noncollagenous domain 16a as diagnostic biomarkers in mucous membrane pemphigoid

BACKGROUND

Mucous membrane pemphigoid (MMP) is an uncommon mucocutaneous immunobullous disorder. Use of saliva for diagnosis by enzyme-linked immunosorbent assay (ELISA) using the noncollagenous (NC) domain 16a of bullous pemphigoid antigen II (BP180) is not well described.

OBJECTIVE

To establish whether whole or parotid saliva is a suitable alternative to serum for diagnosis of MMP.

METHODS

Precoated BP180-NC16a ELISA plates were used to test serum, and whole and parotid saliva for IgG, IgA and secretory IgA antibodies. Patients with MMP (n = 64) provided matched serum and whole saliva. In addition 18 of the MMP patients also provided matched parotid saliva. Healthy controls (n = 50) provided matched serum and whole saliva and 6 of these additionally provided matched parotid saliva. An additional 16 disease controls provided matched serum, and whole and parotid saliva.

RESULTS

In whole saliva, IgG antibodies were detected in 11/64 (17%), IgA in 23/64 (36%) and a combined positivity in 29/64 (45%). In parotid saliva, IgA antibodies were found in 8/18 (44%). Serum IgG antibodies were detected in 27/64 (42%), serum IgA antibodies in 18/64 (28%) and a combined positivity in 33/64 (52%). Combined use of serum and saliva increased detection of specific antibodies by 30%. Control samples were all negative (positive predictive value of 100% for all tests). The negative predictive values were 62% for IgA saliva, 65% for IgG serum, 59% for IgA serum and 56% for IgG saliva.

CONCLUSIONS

IgG and IgA antibodies may provide a suitable diagnostic marker in MMP. Assay of salivary IgA antibodies to NC16a offers a similar diagnostic predictive value to serum.

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.

Diagnosis and clinical severity markers of bullous pemphigoid

The use of a broad spectrum of novel detection systems for autoantibodies to the basement membrane proteins BP180 and BP230 has greatly facilitated the diagnosis of bullous pemphigoid, which most likely explains its increasing incidence in central Europe. Because the pathogenic relevance of antibodies to human BP180 has been convincingly shown both in vitro and in vivo, repeated testing for these antibodies appears to be helpful in guiding treatment decisions during the course of the disease.

[Mucous membrane pemphigoid with ocular involvement. Part I: Clinical manifestations, pathogenesis and diagnosis]

Mucous membrane pemphigoid is a subepidermal blistering autoimmune disorder characterized by predominant involvement of mucous membranes and the presence of autoantibodies against proteins of the dermal-epidermal junction. Lesions most frequently develop in the oral cavity followed, in descending order of frequency, by conjunctiva, nasopharynx, the anogenital region, skin, larynx, and oesophagus. When the lesions are restricted to the conjunctiva, the term ocular pemphigoid may be applied. Cicatrization of the plica is considered a pathognomonic sign in early disease. Recurrent conjunctival inflammation results in subepithelial fibrosis, which leads to fornix shortening, symblepharon formation and subsequent trichiasis and entropion. Even in the absence of conjunctival inflammation, ankyloblepharon may occur. In end stage disease, limbal stem cell deficiency, tear deficiency, and lid malpositions may occur and result in a total keratinization of the ocular surface. The diagnosis is based on clinical findings and the detection of linear deposits of IgG and/or IgA and/or C3 at the dermal-epidermal junction by direct immunofluorescence microscopy of a perilesional biopsy. Autoantibodies (against type XVII and VII collagen, laminin 5 and 6, alpha6beta4 integrin, BP230) have been detected in patient serum. In the case of ocular involvement, preferential reactivity against beta4 integrin has been described.

IgG anti-laminin-332 autoantibodies are present in a subset of patients with mucous membrane, but not bullous, pemphigoid

BACKGROUND

Antiepiligrin cicatricial pemphigoid is a mucosal-predominant subepidermal blistering disease associated with an increased relative risk of cancer. In contrast to prior reports showing that anti-laminin (L)-332 autoantibodies are a reliable marker for patients with antiepiligrin cicatricial pemphigoid, a recent report suggested that as many as 40% of patients with bullous pemphigoid (BP) have IgG reactive with this laminin isoform.

OBJECTIVE

We sought to determine whether patients with BP possess circulating IgG anti-L-332 autoantibodies.

METHODS

Sera from 100 adults with BP were analyzed by indirect immunofluorescence testing of intact skin, immunoblot studies of human keratinocyte (HK) extracts, and a new L-332 enzyme-linked immunosorbent assay. Sera showing reactivity suggestive of anti-L-332 autoantibodies in these assays were further analyzed in immunoblot studies of HK extracellular matrix and immunoprecipitation studies of biosynthetically radiolabeled HK extracts.

RESULTS

IgG from all patients with BP bound intact epidermal basement membrane by indirect immunofluorescence microscopy and immunoblotted bullous pemphigoid antigen-1, -2, or both in HK extracts. None of these sera immunoblotted L-332 in HK extracts, although 13 did score above the cut point of a new IgG(4) L-332 enzyme-linked immunosorbent assay (sensitivity = 0.91, specificity = 0.98, Youden index = 0.89). Further analysis of sera from these 13 patients found: (1) all had IgG that bound the epidermal side of 1 mol/L NaCl split skin by indirect immunofluorescence microscopy; (2) none immunoblotted L-332 purified from HK extracellular matrix; and (3) none immunoprecipitated L-332 from biosynthetically radiolabeled HK extracts.

LIMITATIONS

The basis of false-positive enzyme-linked immunosorbent assay determinations for anti-L-332 IgG among patients with BP is unknown.

CONCLUSION

Anti-L-332 autoantibodies remain a reliable marker for patients with antiepiligrin cicatricial pemphigoid.

[Diagnostic use of autoantibodies]

In the field of dermatology, autoantibody diagnostics are relevant in bullous autoimmune and connective tissue diseases and in certain forms of systemic vasculopathy and psoriatic arthritis. Autoantibody diagnosis of bullous autoimmune skin diseases is an area of dermatology, while serodiagnosis of the other diseases is also performed in rheumatology or in large laboratory centers. Antibody diagnosis of bullous skin diseases is more targeted, as the localization, molecular structures, and function of the relevant epidermal or dermal autoantigens are now known to a large extent, and there are sound experimental indications of the pathogenetic role of these autoantibodies. In practical terms, it is important that some of these antibodies are not only used for the initial diagnosis but also to evaluate the course of the disease and the success of treatment. The autoantibody profile in patients with connective tissue disease may also be disease specific, whereas the pathogenetic significance of these autoantibodies, which are usually directed against nuclear and cytoplasmic components or membrane receptors, is still largely unknown. Autoantibody diagnosis is also important in practice in certain vascular diseases. The future will show whether the determination of antibodies against cyclic citrullinated peptides will become more important in diagnosing and following the course of psoriatic arthritis in practice.

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.

Ocular cicatricial pemphigoid

PURPOSE OF REVIEW

To review the content and importance of articles on ocular cicatricial pemphigoid (OCP), or mucous membrane pemphigoid (MMP) with relevance to ocular involvement, published from 2005 to 2006.

RECENT FINDINGS

There is wide antigenic heterogeneity in MMP and OCP and attempts are being made to link this with clinical variations with varying degrees of success. A larger study demonstrates a link between multiple autoantibody reactivity and disease severity. Details of epitope specificity are emerging. A highly sensitive ELISA for laminin 5 has been developed which may provide prognostic information.Clinically, younger OCP patients show more severe ocular disease and are less well controlled by medication. A systematic review shows good evidence only for steroids and cyclophosphamide in OCP. Continued small trials suggest some role for the expensive intravenous immunoglobulin therapy in OCP where conventional treatment fails. Ocular reconstruction surgery has made some progression, and is enhanced by adjunctive medical therapy; osteo-odonto-keratoprosthesis offers some hope of prolonged retention of limited vision in end-stage disease.

SUMMARY

OCP remains a difficult disease to manage well and the progress being made in understanding disease mechanisms is whence true disease-modifying, safe therapy is likely to emerge in the future.

Target proteins in inherited and acquired blistering skin disorders

Maintenance of an intact epidermis depends on secure adhesion between adjacent keratinocytes, and between basal keratinocytes and the underlying epidermal basement membrane. The major adhesion units that achieve this are the hemidesmosomes and desmosomes, but when these structures are disrupted, e.g., by gene mutations or autoantibodies, the resilience of the epidermis is lost and blisters develop. Recently, there have been considerable advances in our knowledge of the proteins and glycoproteins that contribute to maintaining keratinocyte adhesion via hemidesmosomes and desmosomes, as well as new insights into the molecular pathogenesis of several inherited and autoimmune blistering skin diseases. These new basic scientific data are clinically relevant, helping to improve patient management and to provide a rationale for developing better and more specific treatments for patients with inherited or acquired blistering skin diseases. In addition, there have also been improvements in our understanding of the organization and assembly of these adhesion structures, and their involvement in signalling pathways, intricately linked to skin development, wound healing and tumour invasion. This review provides an update on the structure and organization of hemidesmosomes and desmosomes, and on the molecular pathology of their various components that result in bullous skin diseases.

Mucous membrane pemphigoid: an update

PURPOSE OF REVIEW

To review articles on mucous membrane pemphigoid, published between June 2004-May 2005.

RECENT FINDINGS

Decreased glycosylation of mucin was found in patients with ocular cicatricial pemphigoid. A unique antigen in oral mucous membrane pemphigoid has not yet been identified. Increased vascular cell adhesion molecule and intercellular adhesion molecule 1 expression was found in skin of patients affected by mucous membrane pemphigoid. Autoreactive T cells to an epitope of bullous pemphigoid antigen 180 kilodaltons were identified in the blood of some patients with mucous membrane pemphigoid. Circulating IgA against an antigen in mucous membrane pemphigoid was found in about 20% of patients, without prognostic significance. Enhanced sensitivity for direct immunofluorescence was reported if skin biopsy specimens were stored for 24 hours in saline. An enzyme-linked immunosorbent assay for detection of circulating autoantibodies against laminin-5 was developed. Sensitivity was higher than indirect immunofluorescence on salt-split skin and immunoblotting. Patients with younger onset (<60 years) of ocular cicatricial pemphigoid were found to have disease evolution similar to that of an older group (>70 years) but were visually impaired earlier in life. Intravenous immunoglobulin as treatment of ocular cicatricial pemphigoid was found to be superior to conventional immunosuppressants, with fewer side effects and better long-term outcome for halting disease activity. Intraoperative adjunction of mitomycin C during fornix reconstruction with amniotic membrane resulted in achieving a deeper fornix in 83% of patients with various cicatrizing conjunctivitis. Transplantation of cultured epithelial cells of oral mucosa in corneal limbal stem cell deficiency was successful in improving visual acuity and reestablishing corneal transparency in mid- to advanced ocular cicatricial pemphigoid.

SUMMARY

Further advances have been achieved in the field of mucous membrane pemphigoid.