Association of DQw7 (DQB1*0301) with ocular cicatricial pemphigoid

A spontaneous canine model of mucous membrane (cicatricial) pemphigoid, an autoimmune blistering disease affecting mucosae and mucocutaneous junctions

Mucous membrane pemphigoid (MMP) is a rare autoimmune blistering dermatosis of humans that was previously known as cicatricial pemphigoid. It is characterized by vesicles, ulcers and scarring that affect predominantly mucosae and mucocutaneous junctions. Circulating autoantibodies recognize epitopes on basement membrane proteins such as collagen XVII or laminin-5/6. Herein, we describe the clinico-pathological and immunological characteristics of 17 dogs afflicted with a dermatosis homologous to MMP of humans. Patients exhibited vesicles and erosions predominantly on mucous membranes or mucocutaneous junctions of the mouth, nose, eyes, genitalia or anus. Histopathology revealed subepithelial vesicles with variable dermal inflammation. Direct immunofluorescence demonstrated IgG or complement at the dermoepithelial junction. Indirect immunofluorescence using salt-split epithelia permitted the detection of circulating basement membrane-specific IgG autoantibodies in 15 cases. In 11 patients, autoantibodies recognized the NC16A segment of collagen XVII, as determined by salt-split indirect immunofluorescence, immunoblotting using canine keratinocytes and ELISA with synthetic canine peptides. In one dog, autoantiodies bound to the dermal side of salt-split epithelia and recognized epitopes within the 30 kDa carboxy-terminal segment of human collagen XVII. Canine MMP, like its human counterpart, exhibits distinctive clinical signs and histopathological lesions, yet circulating autoantibodies target different antigenic epitopes. This spontaneous canine model of MMP could prove useful for studies on the pathogenesis or therapy of this human disease.

Cicatricial pemphigoid

Cicatricial pemphigoid (CP) is a heterogeneous group of rare, chronic, subepithelial blistering disorders of the mucous membranes and, occasionally, the skin, which can have serious and rarely fatal consequences. The most common clinical features are desquamative gingivitis, oral erosions, and conjunctival fibrosis. Skin lesions occur less frequently and may present as widespread vesicles and bullae, as in bullous pemphigoid (BP). In some patients, the scarring can be a source of significant morbidity because it can result in odynophagia, strictures of the upper aerodigestive tract, or corneal opacities leading to eventual blindness. This article is a comprehensive review and discusses clinical, pathologic, and pathophysiologic aspects of this group of disorders collectively known as CP. (J Am Acad Dermatol 2000;43:571-91.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the clinical spectrum of CP, the histopathologic and immunopathologic characteristics, the differential diagnosis, the treatment, and the natural history of the disease. Furthermore, this learning activity should facilitate early diagnosis of CP and should promote the idea that the involvement of other specialists, including ophthalmologists, otolaryngologists, gastroenterologists, and oral medicine specialists, as appropriate, will aid in providing these patients with the highest quality of care.

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.

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.

Eosinophil granule proteins expressed in ocular cicatricial pemphigoid

BACKGROUND

Blister formation and tissue damage in bullous pemphigoid have been attributed to the release of eosinophil granule proteins--namely, to eosinophil derived cationic protein (ECP) and major basic protein (MBP). In the present investigation these eosinophil granule proteins were studied in the conjunctiva of patients with ocular cicatricial pemphigoid (OCP).

METHODS

Conjunctival biopsy specimens obtained from patients with subacute (n = 8) or chronic conjunctival disease (n = 13) were analysed histologically and immunohistochemically using antibodies directed against EG1 (stored and secreted ECP), EG2 (secreted ECP), MBP, CD45 (common leucocyte antigen), CD3 (pan T cell marker), and HLA-DR (class II antigen).

RESULTS

Subepithelial mononuclear cells, mast cells, and neutrophils were detected in all specimens. The number of mononuclear cells, neutrophils, CD45+ cells, CD3+ cells, and the HLA-DR expression were significantly higher in the subacute than in the chronic disease group. Some eosinophils were found in specimens from five of eight patients with subacute OCP, but in none of the patients with chronic disease. The eosinophil granule proteins (ECP and MBP) were found in the epithelium and substantia propria in patients with subacute conjunctivitis.

CONCLUSIONS

Subepithelial cell infiltration in the conjunctiva greatly differs between subacute and chronic ocular cicatricial pemphigoid specimens. The findings suggest that eosinophil granule proteins may participate in tissue damage in acute phase of inflammation in OCP.

Epitope spreading: lessons from autoimmune skin diseases

Autoimmune diseases are initiated when patients develop aberrant T and/or B cell responses against self proteins. These responses presumably are directed to single immunogenic epitopes on these proteins. Recent data in animal models of autoimmune diseases suggest that the targets of immune responses in autoimmunity do not remain fixed, but can be extended to include other epitopes on the same protein or other proteins in the same tissue, a phenomenon termed "epitope spreading." The "epitope spreading" phenomenon also applies to situations in which tissue damage from a primary inflammatory process causes the release and exposure of a previously "sequestered" antigen, leading to a secondary autoimmune response against the newly released antigen. In experimental autoimmune animal diseases, "epitope spreading" seems to have significant physiologic importance in determining the course and duration of disease. In this paper, we review the current concepts in animal models of autoimmune diseases in order to define the "epitope spreading" phenomenon, and we then propose how this phenomenon might play a significant role in the development and the course of autoimmune skin diseases. Hopefully, an understanding of "epitope spreading" will help the dermatology community to better understand the pathogenesis of autoimmune skin diseases and to rationally fashion disease-specific immune therapy in the future.

Significantly increased occurrence of HLA-DQB1*0301 allele in patients with ocular cicatricial pemphigoid

To determine the immunogenetic characteristics of patients with immune-mediated subepithelial blistering diseases of mucous membranes, we performed HLA-typing for the class II MHC gene DQB1*0301 allele using a direct method. Genomic DNA extracted from Caucasian patients was amplified by polymerase chain reaction using primer pairs specific for the DQB loci followed by Southern blotting with a peroxidase-conjugated sequence-specific oligonucleotide probe. Seventy-six percent (16/21) of patients with ocular mucosal disease (with or without oral mucosal and skin diseases) carried the DQB1*0301 allele; by contrast, only 33% (14/42) of race-, age-, and geography-matched normal individuals carried the DQB1*0301 allele (p < 0.005). The relative risk for ocular disease if DQB1*0301 allele is present is 6.4, similar to the relative risk of 8 for patients with ocular but no oral disease (pure ocular cicatricial pemphigoid, p < 0.025). In patients with oral mucosal disease (with or without ocular mucosal and skin diseases), 68% (15/22) carried the DQB1*0301 allele (p < 0.025). When patients with ocular disease were excluded, however, the increased occurrence of the DQB1*0301 allele in patients with oral disease was not statistically significant (64%, 7/11, p < 0.25). In patients with subepidermal blistering skin disease but no oral or ocular disease, there was no increase in the occurrence of the DQB1*0301 allele (38%, 5/13, p > 0.5). The significantly increased occurrence of the DQB1*0301 allele in patients with ocular mucosal disease may point to a distinct immunogenetic factor that predisposes patients to develop an ocular scarring process.

Ocular cicatricial pemphigoid antigen: partial sequence and biochemical characterization

Ocular cicatricial pemphigoid (OCP) is an autoimmune disease that affects mainly conjunctiva and other squamous epithelia. OCP is histologically characterized by a separation of the epithelium from underlying tissues within the basement membrane zone. Immunopathological studies demonstrate the deposition of anti-basement membrane zone autoantibodies in vivo. Purified IgG from sera of patients with active OCP identified a cDNA clone from a human keratinocyte cDNA library that had complete homology with the cytoplasmic domain of beta 4-integrin. The sera recognized a 205-kDa protein in human epidermal, human conjunctiva, and tumor cell lysates that was identified as beta 4-integrin by its reaction with polyclonal and monoclonal antibodies to human beta 4-integrin. Sera from patients with bullous pemphigoid, pemphigus vulgaris, and cicatricial pemphigoid-like diseases did not recognize the 205-kDa protein, indicating the specificity of the binding. These data strongly implicate a role for human beta 4-integrin in the pathogenesis of OCP. It should be emphasized that multiple antigens in the basement membrane zone of squamous epithelia may serve as targets for a wide spectrum of autoantibodies observed in vesiculobullous diseases. Molecular definition of these autoantigens will facilitate the classification and characterization of subsets of cicatricial pemphigoid and help distinguishing them from bullous pemphigoid. This study highlights the function and importance of beta 4-integrin in maintaining the attachment of epithelial cells to the basement membrane.

A common major histocompatibility complex class II allele HLA-DQB1* 0301 is present in clinical variants of pemphigoid

Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease seen primarily in elderly persons. It is characterized clinically by the development of tense bullae and by the presence of an antibasement membrane antibody. In BP, the antigens involved in the autoimmunity are epidermal basement membrane peptides BPAg1 and BPAg2. We have compared high resolution typing of major histocompatibility complex class II loci (HLA-DRB1, DQB1) in 21 patients with BP, 17 with ocular cicatricial pemphigoid (OCP), and 22 with oral pemphigoid (OP) to a panel of 218 haplotypes of normal individuals. We found that the three diseases (BP, OCP, and OP) have significant association with DQB1*0301 (P = 0.005, P < 0.0001, and P = 0.001, respectively). The frequencies of alleles DQB1*0302, 0303, and 06, which share a specific amino acid sequence from position 71 to 77 (Thr-Arg-Ala-Glu-Leu-Val-Thr) were also increased (P = 0.01). We suggest that an identical major histocompatibility complex class II allele (DQB1*0301) is a common marker for enhanced susceptibility and that the same amino acid residues in positions 71-77 (DQB1*0301, -0302, -0305, -0602, -0603 alleles) are found in patients with BP, OCP and OP. Our findings propose that the autoimmune response in the three different clinical variants of pemphigoid, involves the recognition by T cells of a class II region of DQB1, bound to a peptide from the basement membrane of conjunctiva, oral mucosa, and skin.

Differences in the anti-basement membrane zone antibodies in ocular and pseudo-ocular cicatricial pemphigoid

PURPOSE

Ocular cicatricial pemphigoid (OCP) is a chronic autoimmune cicatrizing disease which affects the conjunctiva and other squamous epithelium, resulting in a scarring process. A similar process, limited only to the conjunctiva, observed in some patients using eye drops for the treatment of glaucoma, is called pseudo-ocular cicatricial pemphigoid (P-OCP). Immunofluorescence studies demonstrate deposition of immunoglobulins and complement components in the basement membrane zone (BMZ) of the conjunctiva and an anti-basement membrane zone antibody in the serum of patients. A striking association between OCP and MHC class II gene DQB1*0301 has been observed. The purpose of this study was to determine some of the differences in the binding of OCP and P-OCP sera to different lysate in an immunoblot assay, in an attempt to partially characterize the OCP and P-OCP antigens. Furthermore, we wanted to determine if the MHC class II gene association of P-OCP is similar to that of OCP.

METHODS

We studied sera from 11 patients with active ocular cicatricial pemphigoid and seven patients with pseudo-ocular cicatricial pemphigoid and controls. Indirect immunofluorescence (IIF) studies were done using monkey esophagus and salt split normal human skin as substrate. A sensitive immunoblot assay (IBA) was developed using normal human epidermis, dermis and conjunctiva as substrate. Typing for MHC class II genes was performed on eight pseudo-ocular cicatricial pemphigoid patients by dot-blot analysis and compared to 38 matched controls.

RESULTS

Weak staining of the basement membrane zone was observed in nine of ten ocular cicatricial pemphigoid sera and five of seven pseudo-ocular cicatricial pemphigoid sera in the IIF assay using monkey esophagus. Using salt split human skin as substrate, ten of eleven ocular cicatricial pemphigoid sera demonstrated low titer weak binding to the epidermal side of the split. No consistent pattern of staining was seen with pseudo-ocular cicatricial pemphigoid sera. Ten of the 11 ocular cicatricial pemphigoid sera demonstrated binding to 230, 205, 160 and 85 kDa proteins in the IBA using normal human epidermis and conjunctiva lysates. When the lysates were first reacted with BP sera and then immunoblotted with ocular cicatricial pemphigoid sera, the 230, 160, and 86 kDa bands disappeared, and only the 205 kDa band persisted. The sera of five of seven pseudo-ocular cicatricial pemphigoid patients bound to 290, 230, 205, 180, 97, and 85 kDa proteins in the epidermis and conjunctiva. However, the 230, 205, 180, and 85 kDa proteins are depleted when the lysates are first reacted with BP and ocular cicatricial pemphigoid sera. In the dermal lysate, the pseudo-ocular cicatricial pemphigoid sera recognize 400, 290, 150 and 45 kDa proteins. None of these are absorbed by BP, ocular cicatricial pemphigoid or pemphigus vulgaris or epidermolysis bullosa acquisita sera. The 290 kDa proteins identified in the dermis and epidermis are distinct from each other. No binding was seen with control sera with the 3 lysates. Statistically, dot-blot analysis did not demonstrate a significant increase in the frequency of the MHC DQB1*0301 gene.

CONCLUSIONS

Patients with ocular cicatricial pemphigoid and pseudo-ocular cicatricial pemphigoid produce several autoantibodies. However, there are similarities and differences between them. The MHC class II genes associated with pseudo-ocular cicatricial pemphigoid are different from those with ocular cicatricial pemphigoid. This provides a new model system to study the immune abnormalities in idiopathic and drug-related organ specific autoimmunity.

HLA-DQB1*0301 association with increased cutaneous melanoma risk

Susceptibility to a variety of malignancies has been linked to human leukocyte antigen (HLA) genes, including the HLA class II allele DQB1*0301. To determine whether melanoma risk is associated with HLA class II alleles, molecular oligotyping of HLA class II-DRB1, -DQA1 and -DQB1 genes was performed for 45 patients with melanoma. The DQB1*0301 allele was present in 56% of melanoma patients vs. 27% of 200 local Caucasian controls. This difference was highly significant (Bonferroni's-corrected chi-square p = 0.003, OR = 3.4). No other class II allele tested was present at significantly increased or decreased frequency in melanoma patients. Furthermore, presence of DQB1*0301 in melanoma patients was associated with advanced disease. Melanoma patients carrying the DQB1*0301 allele presented on average with thicker primary tumors (mean 3.7 mm vs. 1.8 mm, 2-tailed p = 0.02) and were more likely to present with regional or distant metastatic disease (stages III-IV, 44% vs. 5%, chi-square p = 0.003), compared to melanoma patients without DQB1*0301. Risk of melanoma incidence or progression may be influenced by DQB1*0301 or a closely linked gene.

Common major histocompatibility complex class II markers in clinical variants of cicatricial pemphigoid

Cicatricial pemphigoid (CP) is a chronic autoimmune blistering disease affecting multiple mucous membranes derived from stratified squamous epithelium and occasionally the skin. CP has a wide spectrum of disease manifestations. Patients with oral pemphigoid (OP) have a benign self-limited disease in which pathological changes are restricted to the oral mucosa. On the other hand, patients with ocular cicatricial pemphigoid (OCP), a chronic condition marked with relapses and remissions, have ocular involvement and also perhaps involvement of other mucous membranes. All clinical subsets are characterized by the presence of a similar anti-basement zone autoantibody. The factors that determine the development of one form of CP or the other are not known. In a previous study, we described the association between OCP and the DQB1*0301 allele (P = 0.006). In this study, we have analyzed 22 Caucasian patients with OP and their family members for major histocompatibility complex DRB generic, DQA1, and DQB1 allele associations by PCR-sequence-specific oligonucleotide probe hybridization. The results were compared to those obtained from 17 Caucasian patients with OCP and to control Caucasian alleles and haplotypes. The DQB1*0301 allele frequency was 38.6% in OP, 52.9% in OCP, and 17.8% in controls. Statistically significant associations were detected between the DQB1*0301 allele and both OP (P = 0.0047) and OCP (P < 0.0001). In addition, DRB1*04 showed a statistically significant association (P = 0.005) with OCP when compared to controls. Analysis of major histocompatibility complex class II haplotypes showed significant statistical associations between both OCP and OP and the HLA-DRB1*04, DRB4*0101, DQA1*03, DQB1*0301 haplotype (P < 0.0001 and P = 0.0012, respectively). Our results indicate that DQB1*0301 is a marker of both oral and ocular forms of CP. The analysis of the amino acid sequence of the DQB1 alleles present in both OP and OCP suggested that amino acid residues at position 57 and positions 71-77 may also be markers of CP.

The immunological features and pathophysiology of ocular cicatricial pemphigoid

Ocular cicatricial pemphigoid is an uncommon but severe and potentially blinding systemic disease. It shares many pathophysiological features with the other bullous skin diseases such as dermatitis herpetiformis, bullous pemphigoid and pemphigus vulgaris. All of these diseases have circulating antibodies that bind to the basement membrane of mucous membranes. The individual diseases differ by each having a specific component of the basement membrane complex as its antigen. In acute ocular cicatricial pemphigoid, the conjunctiva is infiltrated with neutrophils, macrophages, Langerhans cells and CD8+ and CD4+ T-cells while in the chronic disease the conjunctiva is infiltrated mainly by CD8+ T-cells. There is evidence of activation of these T-cells as CD4+ cells as shown by expression of the interleukin-2 receptor and increased expression of major histocompatibility class II antigens within the tissue. The aetiology of the fibrosis is unknown but increased amounts of several fibrogenic growth factors are demonstrable by immunohistochemistry.

Report on the sequence of DQB1*0301 gene in ocular cicatricial pemphigoid patients

Ocular cicatricial pemphigoid (OCP) is an autoimmune disease that affects the conjunctiva and other mucous membranes. Major histocompatibility complex (MHC) class II genes are important in autoimmunity because the antigen is presented to the T cell receptor in association with these molecules. A highly statistically significant association has been observed between patients with OCP and DQw7 (DQB1*0301) gene. DNA sequences of the second and third exons of the DQB1*0301 gene were determined in three OCP patients and compared with a control homozygous cell line for DQw7 from the Tenth International Histocompatibility Workshop. The sequences were identical in the patients studied and reference cell line. This data indicates that DQB1*0301 may only partly provide the enhanced susceptibility to get OCP and that another gene(s) in linkage disequilibrium with it and other factors may play an important role in the pathogenesis.