Dermatitis herpetiformis: from the genetics to the development of skin lesions

Serum reactivity in dermatitis herpetiformis: an international multicentre study

BACKGROUND

Dermatitis herpetiformis (DH) is a rare gluten-induced skin disorder characterized predominantly by IgA autoantibodies against endomysium, tissue transglutaminase (TG2/tTG), epidermal transglutaminase (TG3/eTG) and deamidated gliadin. To date, circulating autoantibody reactivity has not been systematically described.

OBJECTIVES

Characterization of serum reactivities in DH.

METHODS

This multicentre international study analysed sera from 242 patients with DH taken at the time of initial diagnosis. DH-specific IgA and IgG serum autoantibodies were analysed by indirect immunofluorescence (IF) on monkey oesophagus, and by enzyme-linked immunosorbent assay (ELISA) based on recombinant TG2/tTG, TG3/eTG and deamidated gliadin (GAF3X).

RESULTS

IgA indirect IF microscopy on monkey oesophagus revealed the highest reactivity (84.3%; specificity 100%) followed by IgA TG2/tTG ELISA (78.5%, specificity 99.0%), IgA TG3/eTG ELISA (72.7%, specificity 95.0%) and IgA GAF3X ELISA (69.0%, specificity 98.5%).

CONCLUSIONS

Serum IgA and IgG autoantibodies against endomysium, TG2/tTG, TG3/eTG and deamidated gliadin are highly prevalent in DH. Indirect IF microscopy on monkey oesophagus (IgA) provides the highest diagnostic accuracy that can be further enhanced by 4.5% when combined with IgA TG2/tTG ELISA.

Role of Human Leukocyte Antigen Class II in Antibody-Mediated Skin Disorders

HLA class II molecules are key factors determining susceptibility to autoimmune disorders, and their role in immune-mediated skin conditions such as psoriasis has been extensively investigated. However, there is currently little understanding of their role in antibody-mediated skin diseases such as autoimmune blistering disorders. We researched the available literature using PubMed to narratively review the current knowledge on HLA associations in antibody-mediated blistering skin pathologies. Our results summarized the risk alleles that are identified in the literature, together with certain known protective alleles: in the pemphigus group, alleles HLA-DQB1*0503 and HLA-DRB1*0402 are most commonly associated with disease; in the pemphigoid group, the most studied allele is HLA-DQB1*0301; in epidermolysis bullosa acquisita, few genetic studies are available; in dermatitis herpetiformis, the association with haplotypes HLA-DQ2 and HLA-DQ8 is strongly established; finally, in linear IgA bullous disease, specific HLA alleles may be responsible for pediatric presentations. Our current pathogenic understanding of this group of disorders assigns a key role to predisposing HLA class II alleles that are able to bind disease autoantigens and therefore stimulate antigen-specific autoreactive T cells. The latter engage B lymphocytes that will produce pathogenic autoantibodies. The distribution of HLA alleles and their disease associations are variable across demographics, and an in-depth pathogenetic understanding is needed to support associations between HLA alleles and disease phenotypes. Additionally, in a personalized medicine approach, the identification of HLA alleles associated with the risk of disease may become clinically relevant in identifying susceptible subjects that should avoid exposure to known triggers, such as medication, when possible.

Clinicopathological Profile of Dermatitis Herpetiformis Patients in Saudi Arabia

Objectives The aim of this study was to describe the clinical, serological, and histopathological features of patients with dermatitis herpetiformis (DH) in Saudi Arabia. Methods We retrospectively reviewed the medical charts of all patients diagnosed with DH in the dermatology departments of National Guard Health Affairs (NGHA) hospitals in five different cities, from 2016 to 2022. We included patients who had been diagnosed by a dermatologist and had a combination of typical DH skin lesions, positive immunoglobulin A (IgA) on direct immunofluorescence (DIF), and/or positive tissue transglutaminase (tTG) IgA. Results A total of 11 patients were included. Their average age was 43.6 ± 12.5 years, and the ratio of females: males was 2.7: 1. Among the eight skin biopsies performed, IgA was detected on DIF in five patients. Seven out of nine patients (77.8%) had positive tTG IgA. Nine patients were managed with dapsone and a gluten-free diet (GFD); they had excellent responses within months. Conclusion The profiles of Saudi patients with DH were similar to those of Caucasian patients, but DH appears to be less common in Saudi Arabia. The high positive rates of tTG IgA make it an important tool for diagnosis in unclear cases. Dermatitis herpetiformis is likely associated with underlying gluten-sensitive enteropathy in Saudi patients.

Skin gluten-related disorders: new and old cutaneous manifestations to be considered

The term gluten-related disorders (GRD) refer to a spectrum of different clinical manifestations triggered by the ingestion of gluten in genetically susceptible individuals, including coeliac disease (CD), wheat allergy and non-celiac gluten sensitivity (NCGS). GRD are characterized by a large variety of clinical presentations with both intestinal and extra-intestinal manifestations. The latter may affect almost every organ of the body, including the skin. Besides the well-known association between CD and dermatitis herpetiformis, considered as the cutaneous specific manifestation of CD, many other muco-cutaneous disorders have been associated to GRD. In this review, we analyzed the main features of dermatological diseases with a proven association with GRD and those that improve after a gluten-free diet, focusing on the newly described cutaneous manifestations associated with NCGS. Our main hypothesis is that a "cutaneous-gluten sensitivity," as specific cutaneous manifestation of NCGS, may exist and could represent a diagnostic marker of NCGS.

Primate liver tissue substrate in indirect immunofluorescence diagnostics for patients with dermatitis herpetiformis and celiac disease

Introduction

Dermatitis herpetiformis (DH) is a rare autoimmune, polymorphous blistering disorder, characterized by severe itch or burning sensation, which represents the cutaneous manifestation of celiac disease (CD). The current estimation of DH versus CD is around 1:8 and the affected individuals have a genetic predisposition. Pathogenetically, IgA autoantibodies against the epidermal transglutaminase, an essential constituent of the epidermis, cause DH and are reported to develop through cross-reaction with the tissue transglutaminase, with IgA auto-antibodies causing CD. Immunofluorescence techniques allow for a rapid diagnostics of the disease using patient sera. Evaluation of IgA endomysial deposition with indirect immunofluorescence on monkey oesophagus is highly specific, but moderately sensitive, with some operator-dependent variability. Recently, indirect immunofluorescence with monkey liver as a substrate has been proposed as an alternative, well-functioning diagnostic approach with higher sensitivity in CD.

Methods

The objective of our study was to evaluate whether monkey oesophagus or liver tissue shows advantage for diagnostics in patients with DH, compared to CD. To that end, sera of 103 patients with DH (n=16), CD (n=67) and 20 controls ere compared by 4 blinded experienced raters.

Results

For DH, we found a sensitivity of 94.2% for monkey liver (ML) compared to 96.2% in monkey oesophagus (ME), while specificity in ML was superior (91.6% versus 75%) to ME. In CD, ML had a sensitivity of 76.9% (ME 89.1%) and specificity of 98.3% (ME 94.1%).

Discussion

Our data show that ML substrate is well suitable for DH diagnostics.

Doubtful Justification of the Gluten-Free Diet in the Course of Hashimoto's Disease

The popularization of the gluten-free diet brings with it a fashion for its use, which can harm the treatment of Hashimoto's disease. The few studies in this regard do not confirm positive changes resulting from a gluten-free diet. At the same time, the presence of other comorbid autoimmune diseases in this group of patients is increasing. This may have important implications for the interpretation of test results and the need for a gluten-free diet in some patients. In this review, the PubMed database was searched for links between a gluten-free diet, Hashimoto's disease, and autoimmune diseases. When analyzing the available literature, we found no basis for introducing a gluten-free diet for the standard management of Hashimoto patients. The recommended diet is instead an anti-inflammatory diet that levels the supply (to compensate for deficiencies) of vitamin D, iodine, and selenium, which are found in plant products rich in polyphenols, antioxidants, and omega-3 fatty acids, as illustrated in this article.

Dermatitis Herpetiformis: An Update on Diagnosis, Disease Monitoring, and Management

Dermatitis herpetiformis (DH), Duhring disease, is caused by gluten sensitivity and affects 11.2 to 75.3 per 100,000 people in the United States and Europe with an incidence of 0.4 to 3.5 per 100,000 people per year. DH is characterized by a symmetrical blistering rash on the extensor surfaces with severe pruritus. The diagnosis continues to be made primarily by pathognomonic findings on histopathology, especially direct immunofluorescence (DIF). Recently, anti-epidermal transglutaminase (TG3) antibodies have shown to be a primary diagnostic serology, while anti-tissue transglutaminase (TG2) and other autoantibodies may be used to support the diagnosis and for disease monitoring. Newly diagnosed patients with DH should be screened and assessed for associated diseases and complications. A gluten-free diet (GFD) and dapsone are still mainstays of treatment, but other medications may be necessary for recalcitrant cases. Well-controlled DH patients, managed by a dermatologist, a gastroenterologist, and a dietician, have an excellent prognosis. Our review comprehensively details the current diagnostic methods, as well as methods used to monitor its disease course. We also describe both the traditional and novel management options reported in the literature.

Evaluation of a Bi-Analyte Immunoblot as a Useful Tool for Diagnosing Dermatitis Herpetiformis

Immune responses to tissue transglutaminase (tTG) and nonapeptides of gliadin (npG) are associated with dermatitis herpetiformis (DH), a gluten-related dermatosis. Recently, a bi-analyte immunoblot (b-aIB) was introduced to detect IgA antibodies in response to tTG and npG. We compared the utility of ELISA and b-aIB with tTG in serological diagnoses of DH and their agreement with direct immunofluorescence (DIF). In total, 55 sera (27 DIF-positive DH patients, 4 DIF-negative DH patients and 24 healthy controls) were examined. ELISA for anti-tTG IgA, b-aIB for anti-npG and anti-tTG IgA, and statistical analysis were performed. The b-aIB with tTG showed 78% sensitivity, 100% specificity, 100% positive predictive value, and 82% negative predictive value in relation to ELISA. A better rate of agreement (Cohen’s kappa values) in IgA detection was observed in the pair tTG ELISA and b-aIB with npG (0.85) than in pairs tTG ELISA and b-aIB with tTG (0.78) or b-aIB with tTG and b-aIB with npG (0.78). No degree of agreement was found between serological tests and DIF. Both serological tests may be used to detect the anti-tTG IgA in DH patients. Still, DH diagnosing requires careful consideration of clinical data as well as results of tissue imaging (crucial DIF) and immunoserological techniques detecting DH-type features.

T Cell Response Toward Tissue-and Epidermal-Transglutaminases in Coeliac Disease Patients Developing Dermatitis Herpetiformis

The reason why only few coeliac patients develop the cutaneous manifestation of the disease, named dermatitis herpetiformis (DH), is still unknown. Epidermal transglutaminase (TG3) has been described as the main autoantigen of humoral immunity in DH but the mechanisms leading to this autoimmune response remain obscure. Here we characterized T cells from skin, gut and peripheral blood of DH and coeliac disease (CD) patients, evaluated the impact of the gluten-free diet on circulating T lymphocytes’ phenotype and investigated antigen specific T cell response toward epidermal and tissue transglutaminase (TG2). DH patients showed an increased frequency of skin-derived T cells producing TNFα when compared to CD patients. Moreover, circulating T cells producing TNFα and IL-17A positively correlated with clinical score of skin disease activity and decreased after gluten-free diet. Finally, TG2 and TG3-specific T cells resulted more reactive to antigens stimulation in DH patients and showed cross reactivity toward the two autoantigens in both the group of patients. Our data suggest a role of TNFα and IL-17A producing cells in the development of DH and, for the first time, show the existence of a crossed T cell response toward the two transglutaminases isoforms, thus suggesting new insights on T cells role in skin damage.

The Gluten Gene: Unlocking the Understanding of Gluten Sensitivity and Intolerance

Wheat flour is one of the most important food ingredients containing several essential nutrients including proteins. Gluten is one of the major protein components of wheat consisted of glutenin (encoded on chromosome 1) and gliadin (encoded on chromosome 1 and 6) and there are around hundred genes encoding it in wheat. Gluten proteins have the ability of eliciting the pathogenic immune responses and hypersensitivity reactions in susceptible individuals called “gluten-related disorders (GRDs)”, which include celiac disease (CD), wheat allergy (WA), and non-celiac gluten sensitivity (NCGS). Currently removing gluten from the diet is the only effective treatment for mentioned GRDs and studies for the appropriate and alternative therapeutic approaches are ongoing. Accordingly, several genetic studies have focused on breeding wheat with low immunological properties through gene editing methods. The present review considers genetic characteristics of gluten protein components, focusing on their role in the incidence of gluten-related diseases, and genetic modifications conducted to produce wheat with less immunological properties.

Gut microbiota and aging

Aging is characterized by the functional decline of tissues and organs and increased risk of aging-associated disorders, which pose major societal challenges and are a public health priority. Despite extensive human genetics studies, limited progress has been made linking genetics with aging. There is a growing realization that the altered assembly, structure and dynamics of the gut microbiota actively participate in the aging process. Age-related microbial dysbiosis is involved in reshaping immune responses during aging, which manifest as immunosenescence (insufficiency) and inflammaging (over-reaction) that accompany many age-associated enteric and extraenteric diseases. The gut microbiota can be regulated, suggesting a potential target for aging interventions. This review summarizes recent findings on the physiological succession of gut microbiota across the life-cycle, the roles and mechanisms of gut microbiota in healthy aging, alterations of gut microbiota and aging-associated diseases, and the gut microbiota-targeted anti-aging strategies.

An updated overview of spectrum of gluten-related disorders: clinical and diagnostic aspects

The incidence of gluten-related disorders (GRDs) continues to increase and its global prevalence is estimated at approximately 5% of the population. Celiac disease (CD), dermatitis herpetiformis (DH), gluten ataxia (GA), wheat allergy (WA), and non-celiac gluten sensitivity (NCGS) are the five major GRDs that present with a wide range of clinical manifestations. The diagnosis of GRDs can be challenging because the typical and atypical clinical manifestations of the GRDs overlap. In this review, the current definitions of gluten-related disorders, focusing on their clinical features, diagnostic and therapeutic approaches are presented. We concluded that GRDs are usually diagnosed using a combination of clinical features, serological tests, and histopathological findings. Treatment usually involves dietary modification.

Celiac-Related Autoantibodies and IL-17A in Bulgarian Patients with Dermatitis Herpetiformis: A Cross-Sectional Study

Background and objectives: Dermatitis herpetiformis (DH) is a blistering dermatosis, which shares common immunologic features with celiac disease (CD). The aim of the present study was to explore the performance of a panel of CD-related antibodies and IL-17A in Bulgarian patients with DH. Materials and Methods: Serum samples from 26 DH patients at mean age 53 ± 15 years and 20 healthy controls were assessed for anti-tissue transglutaminase (anti-tTG), anti-deamidated gliadin peptides (anti-DGP), anti-actin antibodies (AAA), and IL-17A by enzyme linked immuno-sorbent assay (ELISA), as well as anti-tTG, anti-gliadin (AGA), and anti-Saccharomyces cerevisiae antibodies (ASCA) using immunoblot. Results: The average serum levels of anti-tTG, anti-DGP, AGA, AAA, and the cytokine IL-17A were at significantly higher levels in patients with DH compared to the average levels in healthy persons which stayed below the cut-off value (p < 0.05). Anti-DGP and anti-tTG antibodies showed the highest diagnostic sensitivity and specificity, as well as acceptable positive and negative predictive value. None of the healthy individuals was found positive for the tested antibodies, as well as for ASCA within the DH group. All tests showed good to excellent correlations (r = 0.5 ÷ 0.9, p < 0.01). Conclusions: Although the diagnosis of DH relies on skin biopsy for histology and DIF, serologic testing of a panel of celiac-related antibodies could be employed with advantages in the diagnosing process of DH patients. Furthermore, DH patients who are positive for the investigated serologic parameters could have routine monitoring for gastrointestinal complications typical for the gluten-sensitive enteropathy.

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.

A subset of patients with pemphigoid (herpes) gestationis has serological evidence of celiac disease

BACKGROUND

Pemphigoid (herpes) gestationis (PG) is an uncommon, self-limited disease with other autoimmune associations; however, celiac disease (CD) is not recognized as one.

METHODS

From 71 patients' sera submitted for herpes gestationis factor (HGF) testing over a 5-year period, 12 were consistent with PG demonstrating HGF and increased IgG BP180 antibody levels; these sera were tested for IgA and IgG endomysial antibodies (EMA), epithelial basement membrane zone and cell surface antibodies by indirect immunofluorescence, and for IgA and IgG tissue transglutaminase (transglutaminase 2 or TG2) antibodies, IgA epidermal transglutaminase (transglutaminase 3 or TG3) antibodies, IgG BP230, and IgG desmoglein 1 and desmoglein 3 antibodies by enzyme-linked immunosorbent assays (ELISAs).

RESULTS

Three of 12 patients' sera with PG (25%) had CD antibodies with positive IgA EMA and increased IgA TG2 antibody levels; two of these had positive IgG EMA, and one other had an increased IgA TG3 antibody level.

CONCLUSIONS

A subset of patients with serological findings of PG also has serological evidence of CD, which may have implications in the etiopathogenesis of PG and which reveals important information about the mother's, and possibly her infant's, health.

Importance of serological tests in diagnosis of autoimmune blistering diseases

Autoimmune blistering diseases are organ-specific autoimmune diseases characterized by autoantibodies against structural proteins that maintain cell-cell (pemphigus diseases) and cell-matrix adhesions (pemphigoid diseases) in the skin and mucous membranes. Over the last few decades, identification of autoantigens and extensive characterization of autoantibodies have improved understanding of the pathogenesis of these diseases. In addition, the development of new sensitive and specific immunoassays enabled accurate diagnosis and proper evaluation of disease activity in autoimmune blistering diseases. In this review, we describe practical updates for molecular diagnostic tests for autoimmune blistering diseases and the basis for interpreting the results of the assays.

Retrospective Study on Autoimmune Blistering Disease in Paediatric Patients

BACKGROUND

Autoimmune blistering diseases (AIBDs) are rare in children and their prevalence in Singapore is unclear. We aimed to investigate the clinical and immunopathologic characteristics of children diagnosed with AIBDs in Singapore.

MATERIALS AND METHODS

The clinical and histology databases at the National Skin Centre in Singapore were searched to identify patients younger than 18 years old diagnosed with an AIBD from January 1, 1998, through December 31, 2012. Patient demographic characteristics, presentation, triggers, investigations, treatments, and disease course were analyzed.

RESULTS

Twelve patients with AIBDs were identified; five (41.7%) had linear immunoglobulin A disease (LAD); two (16.7%) each had pemphigus vulgaris (PV), bullous pemphigoid, and bullous systemic lupus erythematosus; and one (8.3%) had pemphigus foliaceus. Four (33.3%) were female and eight (66.7%) male. The mean age of onset was 8.7 years (range 2-17 years). Most patients were treated with steroids and adjuvant immunosuppressants. Intravenous rituximab was used effectively in a patient with recalcitrant PV. The mean follow-up was 2.35 years (range 0.17-7.33 years). As of the last follow-up, four (33.3%) patients were in complete remission off therapy, two (16.7%) were in complete remission on therapy, four (33.3%) were in partial remission on therapy, and two (16.7%) were lost to follow-up.

CONCLUSION

Consistent with the existing literature, our study shows that LAD is the most common cause of AIBDs in children. Although common in the West, dermatitis herpetiformis was not identified in the current study. Intravenous rituximab may be considered in recalcitrant childhood PV, but vigilant monitoring for side effects is crucial. Immunohistopathologic evaluation is important and repeat biopsies may be of value in patients with atypical disease courses.

Dermatitis herpetiformis: pathophysiology, clinical presentation, diagnosis and treatment

Researches on DH have shown that it is not just a bullous skin disease, but a cutaneous-intestinal disorder caused by hypersensitivity to gluten. Exposure to gluten is the starting point of an inflammatory cascade capable of forming autoantibodies that are brought to the skin, where they are deposited, culminating in the formation of skin lesions. These lesions are vesico-bullous, pruritic, and localized especially on elbows, knees and buttocks, although atypical presentations can occur. Immunofluorescence of perilesional area is considered the gold standard for diagnosis, but serological tests help in cases where it is negative. Patients who follow glutenfree diets have better control of symptoms on the skin and intestine, as well as lower risks of progression to lymphoma. Dapsone remains the main drug for treatment, but it requires monitoring of possible side effects, some potentially lethal.

Genome-wide association study of celiac disease in North America confirms FRMD4B as new celiac locus

We performed a genome-wide association study (GWAS) of 1550 North American celiac disease cases and 3084 controls. Twelve SNPs, distributed across four regions (3p21.31, 4q27, 6q15, 6q25), were significantly associated with disease (p-value <1.0×10⁻⁷), and a further seven SNPs, across four additional regions (1q24.3, 10p15.1, 6q22.31, 17q21.32) had suggestive evidence (1.0×10⁻⁷ < p-value < 1.0×10⁻⁶). This study replicated a previous suggestive association within FRMD4B (3p14.1), confirming it as a celiac disease locus. All four regions with significant associations and two regions with suggestive results (1q24.3, 10p15.1) were known disease loci. The 6q22.31 and 10p11.23 regions were not replicated. A total of 410 SNPs distributed across the eight significant and suggestive regions were tested for association with dermatitis herpetiformis and microscopic colitis. Preliminary, suggestive statistical evidence for association with the two traits was found at chromosomes 3p21.31, 6q15, 6q25, 1q24.3 and 10p11.23, with future studies being required to validate the reported associations.

Low prevalence of IgA anti-transglutaminase 1, 2, and 3 autoantibodies in children with atopic dermatitis

Background

Atopic dermatitis (AD) is a multifactorial chronic inflammatory skin disease presenting with a relapsing clinical pattern similar to chronic autoimmune disease. Several human transglutaminases have been defined and keratinocyte transglutaminase (TG1) and epidermal transglutaminase (TG3) expressed in the epidermis are associated with epidermal barrier dysfunction. Since impairments to the epidermal barrier represent an important factor in AD, we hypothesized that IgA autoantibodies specific for TG1 (IgA-anti-TG1) and TG3 (IgA-anti-TG3) may affect AD development during childhood.

Methods

Active AD patients (n = 304), 28 patients with biopsy-confirmed coeliac disease (CD), 5 patients with active AD and CD, and 55 control patients without CD and skin diseases were enrolled into the study. IgA-anti-TG1 and IgA-anti-TG3 reactivity was determined using an enzyme-linked immunosorbent assay. IgA-anti-TG2 were defined using a fluoroenzyme immunoassay.

Results

IgA-anti-TG1 antibodies were found in 2% and IgA-anti-TG3 antibodies in 3% of patients with active AD. Two out of the 5 patients with AD and concomitant CD had IgA-anti-TG1 and IgA-anti-TG2 antibodies. In CD patients, 36% of individuals presented with elevated IgA-anti-TG1 antibodies and 18% presented with elevated IgA-anti-TG3 antibodies and all CD patients presented with IgA-anti-TG2 antibodies (significantly different from AD patients and controls, p < 0.05). In CD patients, IgA-anti-TG1 and/or IgA-anti-TG3 seropositivity tended to appear concurrently, whereas only one patient with AD had both types of autoantibodies.

Conclusions

IgA-anti-TG1 and IgA-anti-TG3 seropositivity was rare in active AD but frequent in CD patients. The level of circulating antibodies related to skin lesions could be studied by determining the levels of IgA-anti-TG1 and IgA-anti-TG3 in skin biopsies of AD patients.