Dermatitis Herpetiformis: A Review of Direct Immunofluorescence Findings

Diagnostics for Dermatologic Diseases with Autoantibodies

Background

Dermatologic diseases with autoantibodies were recognized early as autoimmunity became accepted as a pathogenic immunologic concept. Laboratory testing to identify disease-defining autoantibodies and investigate their role in pathophysiology has evolved since.

Content

Blistering dermatologic diseases, profiled by autoantibody production, target epithelial components critical in cell–cell and cell–matrix adhesion, resulting in epithelial separation and other characteristic features of the disorders. This review covers the clinical indications for dermatologic disease-related autoantibody testing, the specifics of procuring specimens to test, the available diagnostic tests, and information provided by the testing. Atypical, uncharacteristic, and less well-known clinical and autoantibody profiles as well as several of the many future prospects for expansion of the testing applications are elaborated on in the online Data Supplement.

Summary

Autoantibody-associated dermatologic diseases are acquired immunologic disorders that have considerable clinical implications affecting essential barrier functions of skin and mucous membranes and causing discomfort, including pain and pruritus. Certain of the diseases can have life-threatening manifestations, and treatments can have significant side-effects. The skin diseases may presage other clinical associations that are important to recognize and treat. Laboratory testing aids in the diagnosis of these diseases through identification of the autoantibodies and is essential for prompt and precise knowledge of the disease type for prognosis, further clinical evaluations, and treatment decisions.

S2k guidelines (consensus statement) for diagnosis and therapy of dermatitis herpetiformis initiated by the European Academy of Dermatology and Venereology (EADV)

INTRODUCTION

Dermatitis herpetiformis (DH) is a chronic, pruritic, gluten-induced skin disorder characterized by subepidermal granular IgA deposition and a variable degree of enteropathy identical to that seen in coeliac disease. So far, there has been no European consensus about the management of DH.

METHODS

The guidelines were created by small subgroups of a guideline committee consisting of 26 specialists from various medical fields and one patients' representative. The members of the committee then discussed the guidelines and voted for the final version at two consensus meetings. The guidelines were developed under the support of the European Academy of Dermatology and Venereology (EADV) and in collaboration with the European Dermatology Forum (EDF).

RESULTS

The guidelines summarize evidence-based and expert-based recommendations (S2 level) for the management of DH (see Appendix).

CONCLUSION

These guidelines will improve the quality of management of DH and support dermatologists in their diagnostic and therapeutic decisions.

Practical Direct Immunofluorescence

Direct immunofluorescence (DIF) remains a valuable tool that may be underused because of perceived challenges in the interpretation, limitations, and processing of DIF specimens. The aim of this review is to provide a practical guide for appropriately incorporating DIF in a variety of clinical diseases, such as autoimmune blistering disorders. In vasculitis, the role of DIF continues to evolve, particularly in the setting of IgA vasculitis. Although typically not indicated for the workup of connective tissue disease, DIF may be helpful in cases with negative serologies, nondiagnostic histologic findings, or scarring alopecia. Practical pearls for biopsy technique, specimen handling, and storage are also discussed.

Coeliac Disease Pathogenesis: The Uncertainties of a Well-Known Immune Mediated Disorder

Coeliac disease is a common small bowel enteropathy arising in genetically predisposed individuals and caused by ingestion of gluten in the diet. Great advances have been made in understanding the role of the adaptive immune system in response to gluten peptides. Despite detailed knowledge of these adaptive immune mechanisms, the complete series of pathogenic events responsible for development of the tissue lesion remains less certain. This review contributes to the field by discussing additional mechanisms which may also contribute to pathogenesis. These include the production of cytokines such as interleukin-15 by intestinal epithelial cells and local antigen presenting cells as a pivotal event in the disease process. A subset of unconventional T cells called gamma/delta T cells are also persistently expanded in the coeliac disease (CD) small intestinal epithelium and recent analysis has shown that these cells contribute to pathogenic inflammation. Other unconventional T cell subsets may play a local immunoregulatory role and require further study. It has also been suggested that, in addition to activation of pathogenic T helper cells by gluten peptides, other peptides may directly interact with the intestinal mucosa, further contributing to the disease process. We also discuss how myofibroblasts, a major source of tissue transglutaminase and metalloproteases, may play a key role in intestinal tissue remodeling. Contribution of each of these factors to pathogenesis is discussed to enhance our view of this complex disorder and to contribute to a wider understanding of chronic immune-mediated disease.

An update on direct immunofluorescence for diagnosing dermatitis herpetiformis

This mini-review presents an update on the direct immunofluorescence (DIF) for diagnosing dermatitis herpetiformis. The DIF of uninvolved, perilesional skin is a crucial laboratory procedure in diagnosing dermatitis herpetiformis (DH). IgA deposits at the dermal-epidermal junction (DEJ) of perilesional skin with DIF can also be found in coeliac patients with inflammatory skin diseases different from DH. In certain patients presenting with the rash resembling DH, the deposition of exclusively C3 at DEJ can be found. The term "granular C3 dermatosis" was proposed to name such a rash. Recent data on DH suggest that perhaps the very concept of DH that we are universally accepting now is misleading and should be revised.

Bullous Diseases in Children: A Review of Clinical Features and Treatment Options

Bullous diseases are uncommon in children; however, as they have the potential to affect quality of life, occasionally have long-term side effects in the setting of scarring processes, and carry a rare risk of underlying malignancy [e.g., with paraneoplastic pemphigus (PNP)], knowledge of their clinical presentation and treatment options is essential. Given the rarity of these conditions, our current state of knowledge is largely derived from case reports and case series, with a paucity of evidence-based recommendations. In this review, we discuss the clinical presentation of and treatment options for linear immunoglobulin A disease, dermatitis herpetiformis, pemphigus vulgaris, pemphigus foliaceus, PNP, bullous pemphigoid, mucus membrane pemphigoid, epidermolysis bullosa acquisita, and inherited epidermolysis bullosa. In general, when these conditions, except for PNP, occur in childhood, they have a better prognosis than when they occur in adults. Clinical, histopathological, and immunologic features frequently overlap, but distinct differences have also been reported, most commonly in clinical presentation. Treatment is often similar to that in adults, although specific considerations are necessary for a pediatric population.

An update on the cutaneous manifestations of coeliac disease and non-coeliac gluten sensitivity

INTRODUCTION

Coeliac disease is a gluten-induced immune-mediated enteropathy, characterised by the expression of specific genotypes and the production of autoantibodies. The inflammatory process specifically targets the intestinal mucosa, but gastrointestinal and extraintestinal signs and symptoms can also be present. Non-coeliac gluten sensitivity (NCGS) can be diagnosed in individuals who have intestinal and/or extraintestinal symptoms related to the ingestion of gluten, but do not have autoantibodies and do not suffer from lesions in the duodenal mucosa. Among the extraintestinal manifestations, cutaneous manifestations are the most common for both diseases.

PURPOSE

We conducted this review to illustrate the common and uncommon features underlying the association of coeliac disease and NCGS with cutaneous manifestations related to gluten ingestion. Areas covered: The roles of innate and adaptive immunity in the cutaneous appearance of gluten sensitivity will be discussed.

[Humoral immune diseases: Cutaneous vasculitis and auto-immune bullous dermatoses]

Humoral immunity is the cause of multiple diseases related to antibodies (IgA, IgG, IgM) produced by the patient. Two groups of diseases are identified. The first group is related to circulating antigen-antibody complexes. The antigens are various. They are often unknown. These immune complexes cause a vascular inflammation due to the complement fixation. Consequently, this group is dominated by inflammatory vasculitis. In the second group, the pathology is due to the fixation in situ of antibodies to a target antigen of the skin that is no more recognized by the patient. This group is represented by the auto-immune bullous dermatoses.

Patients with a new variant of endemic pemphigus foliaceus have autoantibodies against arrector pili muscle, colocalizing with MYZAP, p0071, desmoplakins 1 and 2 and ARVCF

BACKGROUND

We identified a new variant of endemic pemphigus foliaceus in El Bagre, Colombia, South America, which we term El Bagre-EPF, and observed reactivity to arrector pili muscle (APM), thus we tested for autoimmunity to APM.

METHODS

We took skin biopsies from 30 patients with El Bagre-EPF and 30 healthy controls (HCs) matched by age, sex and occupation, who were all from the endemic area, and tested these using direct immunofluorescence (DIF), confocal microscopy, immunohistochemistry and immunoblotting (IB).

RESULTS

Of the 30 patients with El Bagre-EPF, 27 had autoantibodies to APM that colocalized with commercial antibodies to myocardium-enriched zonula occludens-1-associated protein (MYZAP), desmoplakin (DP)1 and DP2, plakophilin 4, and Armadillo repeat gene deleted in velo-cardio-facial syndrome (ARVCF) (P < 0.001, Fisher exact test). The positive staining also colocalized with Junctional Adhesion Molecule 1 (JAM-A), a control antibody for gap cell junctions. No HC samples were positive. In 27 of the 30 patients, serum that was APM-positive also displayed IB colocalization of their autoantibody molecular weights with the Progen antibodies (P < 0.001, Fisher exact test).

CONCLUSIONS

Patients affected by El Bagre-EPF have autoantibodies to APM, colocalizing with the antibodies MYZAP, ARVCF, p0071, DP1 and DP2, suggesting that these molecules are El Bagre-EPF antigens. Further, all of these antigens represent components of cell junctions, indicating that the immune response is directed, at least partially, against cell junctions. The immune response in patients affected by El Bagre-EPF is polyclonal, and it includes B and T lymphocytes, mast cells, IgG, IgA, IgM, IgD, IgE, fibrinogen, albumin, complement/C1q, C3c and C4.