HLA type in bullous pemphigoid, cicatricial pemphigoid and linear IgA disease

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.

Bullous Pemphigoid: Trigger and Predisposing Factors

Bullous pemphigoid (BP) is the most frequent autoimmune subepidermal blistering disease provoked by autoantibodies directed against two hemidesmosomal proteins: BP180 and BP230. Its pathogenesis depends on the interaction between predisposing factors, such as human leukocyte antigen (HLA) genes, comorbidities, aging, and trigger factors. Several trigger factors, such as drugs, thermal or electrical burns, surgical procedures, trauma, ultraviolet irradiation, radiotherapy, chemical preparations, transplants, and infections may induce or exacerbate BP disease. Identification of predisposing and trigger factors can increase the understanding of BP pathogenesis. Furthermore, an accurate anamnesis focused on the recognition of a possible trigger factor can improve prognosis by promptly removing it.

Association of HLA class I and class II alleles with bullous pemphigoid in Chinese Hans

BACKGROUND

Bullous pemphigoid (BP) is one of the most common autoimmune skin diseases. Associations of genes, especially human leukocyte antigen (HLA)-DQ alleles, with BP indicate that genetic predisposition contributes to the disease.

OBJECTIVES

To evaluate the association of HLA class I and HLA class II alleles with susceptibility to BP in the northern Chinese Han population.

METHODS

We performed genotype for HLA-A, -B, -C, -G, -DPA1, -DPB1, -DQA1, -DQB1 and -DRB1 loci in 105 patients with BP by Sanger sequence-based typing (SBT) method. These data were compared with a local control cohort of 420 age- and sex-matched cases.

RESULTS

Among the HLA alleles described herein, the susceptibility alleles associated with a high prevalence of BP were A*11:01 (OR = 1.9 Pc = 0.017); B*37:01 (OR = 8, Pc = 1.811 × 10^-6); G*01:01 (OR = 3.61, Pc = 2.839 × 10^-15) and G*01:06 (OR = 2.22, Pc = 0.025); DQA1*01:05 (OR = 4.87, Pc = 5.822 × 10^-5), DQA1*05:05 (OR = 2.64, Pc = 9.114 × 10^-4), and DQA1*05:08 (OR = 10.2, Pc = 0.016); DQB1*03:01 (OR = 1.69, Pc = 0.048) and DQB1*05:01 (OR = 3.42, Pc = 7.28 × 10^-6); and DRB1*10:01 (OR = 6.85, Pc = 2.63 × 10^-6). To the contrary, HLA-DQA1*01:02 (OR = 0.46, Pc = 8.603 × 10^-4) and DQA1*01:03 (OR = 0.38, Pc = 0.048); DQB1*02:02 (OR = 0.28, Pc = 0.016); and DRB1*07:01 (OR = 0.26, Pc = 0.004) had significant associations with protection against BP. In addition, the frequency of haplotype HLA-DRB1*13-DQA1*05-DQB1*03 (OR = 12.32, Pc = 0.026) in BP patients was significantly higher than those in controls.

CONCLUSION

Our data demonstrated that the alleles and haplotypes found in this study may be important differential genetic markers for susceptibility to or protection against BP in individuals of northern Chinese Han population.

A multi-hit hypothesis of bullous pemphigoid and associated neurological disease: Is HLA-DQB1*03:01, a potential link between immune privileged antigen exposure and epitope spreading?

Bullous pemphigoid (BP) is the most common autoimmune blistering disease and is linked to IgG recognition of 2 hemidesmosomal antigens, that is, BP230 (BP antigen 1) and BP180 (BP antigen 2, collagen XVII). The association of BP with other systemic diseases, particularly neurocognitive diseases, provides a potential clue in the underlying pathogenesis of BP. The role of HLA-DQB1*03:01 binding to the immunogenic portion of BP180 provides a potential mechanism by which exposure to neuronal collagen BP180 may lead to cutaneous disease. In our proposed multi-hit hypothesis, patients with underlying neuronal disease are exposed to previously sequestered self-antigen, most importantly BP180. Patients with the HLA-DQB1*03:01 allele show an increased T-cell avidity to several epitopes of BP180, particularly the BP180-NC16a domain. Thus, they have a genetic susceptibility to developing BP upon exposure to the target antigen. In a patient with dysregulation of Th1/Th2 balance, anergy is lost and T-cells are subsequently primed resulting in the development of functional autoimmunity against the BP180-NC16a domain leading to clinically overt disease.

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.

Bullous pemphigoid antigen II (BP180) and its soluble extracellular domains are major autoantigens in mucous membrane pemphigoid: the pathogenic relevance to HLA class II alleles and disease severity

BACKGROUND

Mucous membrane pemphigoid (MMP), a chronic autoimmune subepithelial blistering disease, is associated with circulating IgG and/or IgA autoantibodies against several basement membrane zone antigens. The heterogeneity of clinical presentation and diversity of target autoantigens have contributed to difficulties in characterizing this condition immunologically.

OBJECTIVES

To analyse serum autoantibody profile and HLA class II alleles in MMP patients and to correlate this with the clinical presentation of disease.

METHODS

Well-defined subgroups consisting of 124 patients with MMP were examined for IgG and IgA reactivity with immunoblotting using human epidermal, dermal and placental amnion proteins. The results were further analysed on the basis of detailed clinical (sites of involvement and disease severity) and immunopathological criteria (immunofluorescence study and HLA class II alleles).

RESULTS

Immunoblot assay revealed that the majority of MMP patients had IgG (93 of 124, 75%) and/or IgA autoantibodies (63 of 124, 51%) to BP180 (including its soluble ectodomains, 120-kDa LAD-1 and 97-kDa LABD97 antigens). Other antigens targeted predominantly by IgG autoantibodies included: BP230 in 34 (27%), beta4 integrin in 26 (21%), and laminin 5 in three (2%). All the BP230+ sera and 23 (88%) beta4 integrin+ sera also reacted with at least one of the BP180 antigens. Over 85% of patients with reactivity to beta4 integrin had ocular involvement. In most cases of MMP, more severe clinical features were associated with antibody reactivity to multiple basement membrane zone antigens, as well as reactivity to multiple BP180 component antigens. Dual BP180/LAD-1 reactivity with IgG and IgA was associated with a more severe phenotype. In addition, the subset-dependent autoantibody reactivity correlated well with specific HLA class II alleles, DQB1*0301, DRB1*04 and DRB1*11.

CONCLUSIONS

Our results confirmed that BP180 is a major autoantigen targeted by the sera of patients with MMP. The disease-prevalent HLA class II alleles and humoral autoimmune response against the particular subsets of antigenic epitope(s) within BP180 ectodomain may contribute to the clinicopathological significance and disease severity of MMP.

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).

Three different autoimmune bullous diseases in one family: is there a common genetic base?

We report an unusual familial occurrence of autoimmune bullous diseases. Three members of a family suffered from three different autoimmune bullous diseases: pemphigus vulgaris (PV), linear IgA disease (LAD) and cicatricial pemphigoid (CP). The HLA type was determined in five family members: all were positive for HLA-DQ5/DR6, which is reported to be associated with susceptibility to PV. The CP patient was DQ7(3) positive, which is in concordance with enhanced susceptibility to ocular CP and CP. The LAD patient was B8 and DR3 negative but positive for HLA-A1. Our study supports the hypothesis that there is a genetically transmitted susceptibility to autoimmune bullous diseases but that additional factors seem necessary actually to develop a particular disease.

Desquamative gingivitis and balanitis--linear IgA disease or cicatricial pemphigoid?

A 38-year-old man presented with gingival inflammation together with erosions of the penis. Direct immunofluorescence demonstrated linear deposits of IgA at the basement membrane zone; indirect immunofluorescence and immunoblotting were negative. Linear IgA disease (LAD) was therefore suspected and treatment with dapsone initiated but this was changed to sulfamethoxy-pyridazine and systemic corticosteroids because of methaemoglobinaemia. During 1-year follow-up the lesions continued to wax and wane although they were never as extensive as before. Eighteen months after disease onset there was scarring of the penis together with suspected fibrosis of the inflamed gingival region. In addition the patient was HLA DQ7(3) positive, a haplotype thought to be increased in patients with cicatricial pemphigoid (CP); LAD with scarring or CP with solely linear IgA deposits are possible diagnoses of his condition.

The association of HLA-DQ7 with bullous pemphigoid is restricted to men

This study examines in detail the HLA associations of 74 patients (40 women and 34 men) with bullous pemphigoid (BP) and compares their immunogenetic profile with that of 604 unrelated control subjects (238 women and 366 men). Correlations were sought between HLA antigens and the various BP disease parameters investigated. The presence of milia was the only clinical or laboratory finding which was linked with a specific HLA antigen, HLA-DQ6, in both men and women with BP (P < 0.01). BP has previously been linked with the HLA-DQ7 antigen and this association was confirmed in 39 of our patients (14 women and 25 men). Twelve of these patients (four women and eight men) were homozygous for HLA-DQ7. The association of HLA-DQ7 with BP was gender-restricted and only significant for men (P < 0.01). No equivalent HLA disease susceptibility risk factor could be identified for our female BP patients. This difference in HLA association between men and women with BP has not been reported previously, and its significance for disease pathogenesis is not known. No specific link could be found between HLA-DQ7 and BP for any of the clinical, immunofluorescence, western blotting, treatment or prognostic disease factors studied.

Bullous pemphigoid and multiple sclerosis: a report of three cases and review of the literature

Three patients with longstanding multiple sclerosis (MS) who developed bullous pemphigoid (BP) are reported. All patients had immunological features of typical BP as determined by immunofluorescence and Western immunoblotting studies. The clinical features, however, differed from those observed in typical BP. In two the BP started near an indwelling catheter and two had striking involvement of the soles. None of our patients, or a further nine cases reported in the literature, had mucous membrane involvement. In MS patients BP appears to develop at a younger age. Multiple drugs were taken by the MS patients; these, however, appear not to play a role in triggering their BP. The course of BP in patients with MS is moderate, although the majority require systemic treatment.

Lack of predictive factors for the clinical course of bullous pemphigoid

BACKGROUND

Bullous pemphigoid is a clinically heterogeneous disease although little is known of the factors affecting its course and outcome.

OBJECTIVE

Our purpose was to document the clinical course, outcomes, and causes of death in treated bullous pemphigoid and to determine the predictive factors affecting outcome.

METHODS

The clinical course was documented in 82 patients with immunologically proven bullous pemphigoid (mean follow-up 3 years 2 months). To identify factors predictive of outcome, 16 patients with "good prognosis bullous pemphigoid" (no systemic treatment or in remission within 2 years) were compared with 12 patients with recurrent disease requiring maintenance therapy who still needed treatment after 3 years or longer. Remission was defined as 3 months free of lesions, without systemic treatment.

RESULTS

The disease duration varied from 9 weeks to 17 years (estimated median treatment time 2 years 1 month). Of patients followed up for at least 2 years, 30% achieved remission and by 3 years the remission rate was 50%. Two patients had a subsequent relapse (9%). The mortality rate at 1 year was 19%, and treatment was believed to be contributory in seven deaths. No clinical, immunologic, or immunogenetic factors were predictive of disease duration.

CONCLUSION

Despite the heterogeneity of the clinical course and duration of bullous pemphigoid, no predictive factors are recognized.

The clinical expression of bullous pemphigoid is not determined by the specificity of the target antigen

The major bullous pemphigoid (BP) antigen is a 220-240-kDa polypeptide, although some BP sera recognize bands of 180-200 kDa or lower molecular weight. We have investigated to what extent this heterogeneity of the target antigen accounts for the clinical diversity of BP. Immunoblotting studies against extracts of salt-separated epidermis were performed on sera from 39 patients with BP. The blotting patters obtained were correlated with the clinical findings, with particular reference to prodromal itching, lesion morphology and severity, mucosal involvement, presence of milia, dapsone responsiveness and disease duration. The results confirm that the major BP antigen is a 220-kDa polypeptide, and that the 180-kDa polypeptide is a second and sometimes the sole BP antigen identified in immunoblots. Rarely, multiple bands of lower molecular weight were found. There was no correlation between the pattern of BP antigens detected in immunoblots and the clinical presentation and course of BP. There was considerable clinical diversity even among the nine patients showing specificity for a single 220-kDa target antigen. Although two patients with a single 180-kDa antigen specificity had a disease of unusually long duration, factors other than antigen specificity must determine the clinical expression of BP.

Vesiculo-bullous mucocutaneous disease: benign mucous membrane and bullous pemphigoid

Bullous pemphigoid (BP) and benign mucous membrane pemphigoid (BMMP) are autoimmune diseases characterised by subepithelial bulla formation and showing substantial overlap in clinical signs and symptoms. BP principally involves skin and BMMP the oral mucosa and eyes. The gingiva are affected in 90% of cases of BMMP and buccal mucosa and palate in up to 30%. Lesions may heal with scarring. Extension into the pharynx and esophagus causes sore throat and dysphagia. Severe ocular involvement may cause blindness. Bulla formation is attributed to complement activation, following IgG binding to the basement membrane zone, with subsequent polymorphonuclear leukocyte accumulation. The target antigen in BP is a 180-230 kD protein associated with the basilar membrane of basal keratinocytes. The gene encoding the BP antigen has been partially cloned. It is likely that the same antigen is involved in BMMP, but the mechanism of scarring is not understood. Treatment of BP and BMMP includes systemic steroid and azathioprine therapy and topical steroids.