Class II MHC typing in pemphigoid gestationis

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.

Autoimmune bullous diseases in pregnancy: an overview of pathogenesis, clinical presentations, diagnostics and available therapies

Autoimmune bullous diseases (AIBDs) are rare organ-specific diseases characterized by the appearance of blisters and erosions on the skin and mucous membranes. These dermatoses are marked by the development of autoantibodies targeting the autoantigens located in intercellular junctions, i.e., between keratinocytes or in the basement membrane area. Therefore, the fundamental division of AIBDs into the pemphigus and pemphigoid groups exists. Although AIBDs are uncommon in the general population, their overall incidence is somewhat higher in women of all ages, for which a pregnant women can be likely affected too. While the pemphigoid gestationis is exclusive bullous dermatosis of pregnancy, the other AIBDs can also start or worsen during this period. The appearance of AIBDs in childbearing women is a particularly sensitive situation requiring exceptional clinicians' caution due to the possibility of pregnancy complications with adverse effects and risks to the mother and the child. Also, there are numerous management difficulties in the period of pregnancy and lactation related to the drugs' choice and safety. This paper aimed to outline the pathophysiologic mechanisms, clinical manifestations, diagnostic approach and therapy of the most commonly recognized AIBDs in pregnancy.

Molecular Basis for Global Incidence of Pemphigoid Diseases and Differences in Phenotypes

Pemphigoid (Pg) diseases are a group of potentially fatal autoimmune mucocutaneous diseases. They have different clinical phenotypes, involving only the skin or multiple mucous membranes. They occur globally and frequently affect the elderly. The common marker among all variants is the presence of autoantibodies targeting the dermal-epidermal or mucosal-submucosal junctions, or basement membrane zone (BMZ). Four target antigens in the BMZ were studied. These included BPAG1, BPAG2 and subunits of α6 and β4 human integrins. Our objective was to find a molecular basis for the global incidence of Pg diseases and a mechanism that will explain the vast differences in clinical phenotypes and outcomes. All the variants of Pg that were analyzed had a statistically significant association with HLA-DQβ1*03:01 in ten countries on four continents. This explains the reason for global incidence. Prediction models discovered multiple peptides in each of the four antigens that serve as T cell epitopes. These T cell epitopes were shown to bind to HLA-DQβ1*03:01. In addition, structure modelling demonstrated the peptide-HLA complex bound to the T cell receptor. These autoreactive T cells would stimulate B cells to produce specific anti-BMZ autoantibodies. Anti-BMZ autoantibodies with different specificities will produce different phenotypes, which will account for involvement of different tissues and organs in different molecules. The contribution this study makes is that it provides a molecular basis of why a similar disease occurs in different racial groups. Furthermore, it provides the basis for the production of autoantibodies with different specificities, which resultantly produces different phenotypes.

Influence of pemphigoid gestationis on pregnancy outcome: A case report and review of the literature

Pemphigoid gestationis is considered to be a rare pregnancy exclusive bullous disease, which modifies the course of the pregnancy, with difficulties in the management of the pruritus and skin lesions as well as a possible change in the neonatal outcome. Differential diagnosis of skin lesions and pruritus in pregnancy is challenging, and complementary investigations such as skin biopsy or laboratory tests are indispensable. The correct diagnosis and proper treatment could change the natural course of a pregnancy at risk and could improve maternal and fetal morbidity. We present the case of a patient with pemfigoid gestationis with the aim to highlight: i) the management of this pregnancy-associated skin disorder which transfers this pregnancy into a category of high obstetrical risk pregnancy; ii) the particularities of the course of the pregnancy; and iii) the importance in the differential diagnosis of pregnancy dermatoses. The particularity of this case of pemphigoid gestationis was the acute fetal distress in the absence of intrauterine growth restriction that is frequently found in this pathology, and the management of a rare pregnancy skin condition that currently has no standard treatment.

Subepidermal autoimmune bullous diseases: overview, epidemiology, and associations

Subepidermal autoimmune bullous diseases of the skin and mucosae comprise a large group of chronic diseases, including bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. These diseases are characterized by an antibody response toward structural components of the basement membrane zone, resulting in subepidermal blistering. The epidemiological features of these diseases vary substantially in different regions of the world. Observational studies investigating comorbidities and associations among patients with these diseases are inconsistent and sometimes inconclusive. This review provides a brief overview regarding each one of the subepidermal autoimmune bullous diseases. In addition, it summarizes the most recent understanding of the epidemiological features and associations of this group of organ-specific autoimmune diseases.

Association of anti-RNP with HLADR4 and its prevalence in rheumatoid arthritis patients

BACKGROUND

Autoantibodies are useful diagnostic tools for a variety of rheumatic autoimmune disorders.

OBJECTIVE

The aim of the present study was to investigate autoantibodies against the 70-kD polypeptide of U1 ribonucleoprotein antibodies (RNP) in patients with rheumatoid arthritis (RA) and to investigate the relationship between anti-RNP and HLARD4 in RA patients.

PATIENTS AND METHODS

In this prospective study, we studied 80 RA patients. The patients were classified according to 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria. The patients were 66 females and 14 males. Patients were classified according to activity, duration of disease, and rheumatoid factor. Thirty healthy individuals were included in the study as a control group. Anti-RNP were determined by enzyme-linked immunosorbent assay and HLADR4 was investigated by gel electrophoresis polymerase chain reaction.

RESULTS

Anti-RNP were positive in 32 patients from 80 patients and negative in all control patients. HLADR4 was positive in 53 RA patients from 80 patients and was positive in 6 controls from 30 controls. There was a positive correlation between HLADR4 and anti-RNP (r = 0.368) (P < 0.01). Anti-RNP levels in rheumatoid patients were higher than anti-RNP levels in control patients. Also, there was a positive correlation between anti-RNP and HLADR4 in rheumatoid patients.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

A case of chronic herpes gestationis: persistent disease or conversion to bullous pemphigoid?

We report the case of a 38-year-old woman with herpes gestationis (HG) persistent for 26 months postpartum with typical erythematous-edematous grouped lesions associated with vesicles, blisters, and scaled crusts on most parts of her body. Despite high doses of oral prednisolone, azathioprine, and dapsone, and a trial of 5 plasmaphereses, the disease has persisted to date. Histopathologic examination of lesional skin showed subepidermal blisters, focal basal cell necrosis, and a dermal inflammatory infiltrate including many eosinophils. Direct immunofluorescence showed linear C3 staining in the basement membrane zone and the complement fixation test demonstrated circulating antibasement membrane zone antibodies at a low titer (1:80). HLA typing demonstrated an A2, A24, B35, B52, DR4,5, DR13,15, DRW52,53 phenotype. We present this case as chronic persistent HG and discuss the differential diagnosis between chronic persistent HG and HG evolving to bullous pemphigoid, together with a careful examination of similar cases reported in literature.

Clinicopathological features and HLA tissue typing in pemphigoid gestationis patients in Kuwait

Pemphigoid gestationis (PG) is a rare autoimmune disease of pregnancy. We report a series of 22 cases of PG in Kuwait. They constituted 18% of all the autoimmune bullous diseases registered in our centre over a span of 11 years. PG was observed to be the third most common bullous disease in our region. Ninety-five per cent of the patients were of Arab ethnicity. The clinical features observed in our patients were comparable to those reported elsewhere. Systemic steroids (prednisolone 20-60 mg daily) remained the mainstay of treatment to control the active disease and an optimal dose of 20 mg of prednisolone was maintained throughout the pregnancy and immediate postpartum period. We observed a favourable outcome of pregnancies complicated by PG without any associated maternal or foetal morbidity. Kuwaiti patients with PG were observed to have a predominance of HLA-DR3 and DQ2 antigens. No predominance of HLA-DR4 antigen was observed.

Polymorphic eruption of pregnancy developing in the puerperium

Polymorphic eruption of pregnancy is an uncommon disorder, usually developing in the third trimester and rapidly resolving in the first few weeks postpartum. It has been suggested that multiple pregnancy and excessive weight gain are associated features. We report a patient with the clinical and histological features of polymorphic eruption of pregnancy, whose rash developed 4 weeks after delivery of a singleton pregnancy. An unusual feature of this case was the occurrence of the rash on the face. We discuss this case with respect to the recent literature.

Epitopes targeted by bullous pemphigoid T lymphocytes and autoantibodies map to the same sites on the bullous pemphigoid 180 ectodomain

Bullous pemphigoid is a blistering skin disease characterized by autoantibodies directed against the NC16A domain of bullous pemphigoid 180 (collagen XVII), a transmembrane protein of epidermal basal cells. Passive transfer studies in mice have shown that antibodies that bind to this immunodominant region of bullous pemphigoid 180 are capable of inducing a skin disease that closely mimics bullous pemphigoid, supporting the hypothesis that epitopes within NC16A are involved in the pathogenesis of bullous pemphigoid. In this study, we examined the autoimmune T cell response in bullous pemphigoid patients. T cells from eight of 12 bullous pemphigoid patients, all of whom had circulating anti-bullous pemphigoid 180 autoantibodies, showed a specific proliferative response to recombinant forms of NC16A. T cell lines and clones developed from four of these patients recognize the same NC16A peptides as those targeted by autoantibodies from the corresponding individuals. These NC16A-responding T lymphocytes express alpha/beta T cell receptors and CD4 memory T cell surface markers and exhibited a Th1/Th2 mixed cytokine profile that may support the production of antibodies. This new information will aid in defining the key steps involved in the development of the autoimmune response in bullous pemphigoid.

Polymorphisms of HLA-DR and -DQ genes in Japanese patients with bullous pemphigoid

Bullous pemphigoid (BP), an autoimmune skin disease of the elderly, is mediated by autoantibodies that bind to hemidesmosomes of epidermal basal cells. This study investigated BP-associated HLA-DR and -DQ genes among Japanese patients. We analyzed HLA-DR and -DQ genes among 23 Japanese BP patients based on the polymerase chain reaction-restriction fragment length polymorphism. Eighteen of these 23 patients (78%) carried at least one allele of HLA-DRB1*04 or DRB1*1101, with significant increases in HLA-DRB1*04 (*0403, *0406)/DQA1*0301/DQB1*0302 and DRB1*1101/DQA1*0505/DQB1*0302 haplotypes as well as the individual alleles DRB1*1101 and DQB1*0302 (corrected p < 0.05 for each comparison), when compared to control subjects. These data differ from the accepted DQB1*0301 (DQ7) association with the same disease among Caucasians. These findings indicate that different HLA class II haplotypes genetically influence susceptibility to BP among different ethnic groups. Our findings, together with previous reports on Caucasian patients with the pemphigoid group of bullous diseases, suggest that HLA-DRB1 molecules might participate in the regulation of autoimmune responses to BP antigens.

Adult linear IgA disease and chronic bullous disease of childhood: the association with human lymphocyte antigens Cw7, B8, DR3 and tumour necrosis factor influences disease expression

Linear IgA disease and chronic bullous disease of childhood are both subepidermal autoimmune blistering diseases. Class I and II major histocompatibility locus (MHC) antigen typing was performed on 60 patients (26 chronic bullous disease of childhood, 34 adult linear IgA disease), and the findings were correlated with the clinical course. The typing was performed using a lymphocyte microcytotoxicity assay, and the results were compared with a reference population of U.K. organ donors. Analysis of the tumour necrosis factor (TNF) locus was performed using sequence-specific oligonucleotides on a dot blot in 51 patients and compared with a random control population and human lymphocyte antigen (HLA) DR3 matched controls. The disease was found to be significantly associated with HLA Cw7 (chi2 = 19.24, P = 0.001), B8 (chi2 = 9.89, P = 0.04) and DR3 (chi2 = 10.47, P = 0.014), all components of the common Caucasian haplotype. There was also a close association between the disease and possession of HLA DR2 or 3 (chi2 = 16.34, P = 0.001). A reduction in the incidence of DR1 and DR4 (alleles carrying the rheumatoid motif) was observed, which is more marked in the children (chi2 = 8.34, P = 0.039). In the childhood group there was an increased frequency of B8, DR3 and DQ2 compared with the adults which included five of 26 who were homozygous for these antigens, a feature not seen in the adults, which may account for the differences seen between the two groups. Possession of HLA B8, DR3 and DQ2 probably facilitates earlier presentation of the disease as there is no evidence from our results that the adults and children differ fundamentally in their MHC associations. The rare TNF2 allele was found in 29 of 51 patients (expected 8.2, chi2 = 18. 3, P = 0.0001). This was more marked in the children (19 of 26). Patients with the TNF2 allele had a longer disease duration (5.3 years TNF2, 3.0 years TNF1).

Human leucocyte antigen class II associations in chronic idiopathic urticaria

The major histocompatibility complex (MHC) acts as a marker for self during T-cell ontogeny and is associated with the pathogenesis of many autoimmune diseases. Recent investigations have shown about 30% of patients with chronic idiopathic urticaria (CIU) have IgG autoantibodies against the high-affinity IgE receptor, FcepsilonRI, or IgE. A link between MHC class II alleles and CIU has not been reported previously. DNA was extracted from blood of 100 Caucasian patients with CIU, and the MHC class II type determined using the polymerase chain reaction with sequence-specific primers, testing for DRB and DQB1 alleles. The frequency of alleles in CIU patients was compared with that found in 603 controls. Further human leucocyte antigen (HLA) typing on patient subsets, classified by the patients' responses to intradermal injection of autologous serum and their serum-induced histamine release from basophil leucocytes of healthy donors, was undertaken. HLA DRB1*04 (DR4) and its associated allele, DQB1*0302 (DQ8), are raised in CIU patients compared with a control population (P = 2 x 10-5 and P = 2 x 10-4, respectively). HLA DRB1*15 (DR15) and its associated allele, DQB1*06 (DQ6), are significantly less frequently associated with CIU. The HLA DRB1*04 association is particularly strong (corrected P = 3.6 x 10-6) for patients whose serum has in vivo and in vitro histamine-releasing activity. HLA class II typing is consistent with the concept that CIU is a heterogeneous disease, and supports an autoimmune pathogenesis in a subset of patients.

Identification and Characterization of Epitopes Recognized by T Lymphocytes and Autoantibodies from Patients with Herpes Gestationis

Autoantibodies associated with herpes gestationis (HG), a pregnancy-associated autoimmune skin disease, target the hemidesmosomal protein BP180. It was shown that the major noncollagenous stretch of the BP180 ectodomain (NC16A) harbors epitopes recognized by HG sera. Furthermore, Abs reactive with the homologous domain of murine BP180 are known to trigger a cutaneous blistering disease in mice by passive transfer experiments. The present study was aimed at characterizing the T cell responses and specificities of autoantibodies from two HG patients. Using immunoblotting and T cell proliferation assays, we have identified a 14-amino-acid stretch of the BP180 ectodomain (MCW-1; aa 507–520) that is recognized by both T cells and autoantibodies produced by the HG patients. The neonate born to one of these HG patients showed no signs of skin disease and had no detectable T cell response to the BP180 Ag, but did have a low titer of circulating anti-BP180 autoantibodies, presumably of maternal origin. BP180-specific T cell lines and clones developed from an HG patient specifically reacted with the MCW-1 epitope. The proliferative responses of these clones were restricted to HLA-DR, but not -DQ or -DP. These Ag-specific T cells expressed α/β TCRs and a CD4 memory T cell phenotype and secreted IFN-γ and IL-2, but not IL-4 or IL-6, suggesting that they are Th1-type lymphocytes. Further characterization of these Ag-specific T cells and autoantibodies will aid in elucidating the autoimmune mechanism(s) leading to the development of HG.

Class II major histocompatibility complex typing across the ethnic barrier in pemphigoid gestationis. A study in Mexicans

BACKGROUND

Pemphigoid gestationis (PG), also called herpes gestationis, is a rare autoimmune disease of pregnancy or puerperium (estimated 1 out of 50,000 pregnancies among Caucasians). A previous series has demonstrated an association of PG with human leukocyte antigen (HLA)-DR3 or HLA-DR4 haplotypes. While these haplotypes are most commonly found in individuals of European ancestry, they have also been found in African-American patients affected with PG. PG has rarely been reported in other ethnic groups, and the HLA association in non-Europeans has not been examined.

METHODS

We have characterized eight patients of Mexican ancestry who have PG by clinical, histologic, and immunofluorescence criteria. Class I and class II major histocompatibility complex (MHC) antigens were studied by standard microlymphocytotoxicity assays. Class II MHC antigens were further studied by polymerase chain reaction (PCR) amplification of HLA-DRB1, DQA, and DQB genes and allele-specific oligonucleotide hybridization. For comparison purposes, we used results obtained from a group of 100 ethnically matched healthy individuals.

RESULTS

We found that all eight patients had the HLA-DR3/DR4 phenotype; all HLA-DR3 haplotypes were HLA-DRB1*0301, DQA1*0501, and DQB1*0201, whereas half of the HLA-DR4 haplotypes were from the DRB1*0401 subtype and the other half were DRB1 *0407.

CONCLUSIONS

These results suggest that, in Mexicans, the genetic susceptibility for the development of PG is strongly influenced by the genetic admixture of Caucasian origin, and the role of class II MHC antigens in the pathophysiology of this disease is confirmed.

Dermatoses of pregnancy

Several reported dermatoses of pregnancy have not survived the scrutiny of time and thus including them in current classification schemes does not serve any useful purpose. This review resolves issues in the existing conflicting literature.