A Review Comparing International Guidelines for the Management of Bullous Pemphigoid, Pemphigoid Gestationis, Mucous Membrane Pemphigoid, and Epidermolysis Bullosa Acquisita

Autoimmune blistering disease management can be challenging as treatment modalities vary greatly and no single standard of care exists. We consolidated the recommendations of international management guidelines in order to provide optimal management suggestions to physicians. A comprehensive literature search in PubMed/MEDLINE for published blistering disease management guidelines and consensus statements was conducted in November 2019. Search terms included "guideline or guidelines" or "consensus" and "pemphigoid" or "autoimmune blistering disease" or "epidermolysis bullosa acquisita". We included guidelines from established dermatologic societies and expert consensus groups. We excluded literature reviews, guidelines established by an association without dermatologists, or those specific to a single treatment. Guidelines in all languages were considered. Eleven guidelines from dermatologic associations and consensus groups meeting our inclusion criteria were selected. Several differences between recommendations, most notably when to introduce adjuvants for refractory disease, were found in bullous pemphigoid. In mucous membrane pemphigoid, treatment was directed to the sites involved and managed with systemic corticosteroids and immunosuppressants/biologics. There was no universal consensus on the first-line treatment for epidermolysis bullosa acquisita, but a combination of immunosuppressive, anti-inflammatory, and anti-neutrophil therapy was utilized. Comparison of the management guidelines revealed underrepresentation of guidelines from developing nations and key differences between the management styles among dermatologists from Europe and Asia. We attribute these discrepancies to the time elapsed between guidelines, regional differences, and demands of the local healthcare systems.

Itch in Pregnancy Management

Pruritus is common in pregnancy. It deserves an elaborated work-up of the patient. It is frequently a symptom of a dermatosis that coincides by chance with pregnancy or a preexisting dermatosis that can flare during pregnancy. In some cases, it is due to the group of pregnancy-specific dermatoses. Work-up requires a prudent consideration of the diagnostic tests as well as the choice of treatment because of the potential effects on the fetus. This chapter will focus on the specific dermatoses of pregnancy and the local and systemic treatment of pruritus in general during pregnancy.

Cyclosporine treatment in severe gestational pemphigoid

Gestational pemphigoid, a rare autoimmune skin disease typically occurring during pregnancy, is caused by autoantibodies against collagen XVII. Clinically it is characterised by severe itching followed by erythematous and bullous lesions of the skin. Topical or oral glucocorticoids usually relieve symptoms, but in more severe cases systemic immunosuppressive treatments are needed. Data on immunosuppressive medication controlling gestational pemphigoid are sparse. We report 3 intractable cases of gestational pemphigoid treated with cyclosporine.

Skin disease in pregnancy

Skin manifestations during pregnancy are common and diversified. This review will focus on the most important entities to be recognized by obstetricians. These are, on the one hand, physiological changes, where unnecessary investigations should be avoided, and on the other, the specific dermatoses of pregnancy. These develop electively in pregnancy, and they are currently grouped into three disorders: polymorphic eruption of pregnancy, atopic eczema of pregnancy, and pemphigoid gestationis. Arguments for recognition of these are presented including detection of anti-BP180 antibodies. Follow-up and treatment depend on the precise diagnosis. Risks in fetal prognosis may occur in rare pemphigoid gestationis cases.

A case of pemphigoid gestationis with concurrent IgG antibodies to BP180, BP230 and type VII collagen

A 22-year-old primigravida had a pruritic, erythematous, bullous eruption on the skin during the 26th week of gestation. After delivery the eruption flared up. The diagnosis of pemphigoid gestationis was confirmed based on histopathological and immunofluorescence findings. The result of immunoblotting showed IgG autoantibodies which reacted against BP230 in epidermal extracts and 290 kDa type VII collagen in dermal extracts. The BP180 antibodies were also detected by an enzyme-linked immunosorbent assay BP180NC16a diagnosis kit. Pulsed corticosteroid and cyclophosphamide resulted in a favourable response at the acute stage. The patient was cured in 2 years. The analysis of the patient's autoantibodies provides strong evidence for the involvement of epitope spreading in her autoimmune disease.

[Choriocarcinoma: a hidden face of pemphigoid gestationis]

Gestationis pemphigoid is an autoimmune subepidermal blistering dermatosis occurring predominantly in pregnancy, more seldom in early puerperium, and exceptionally in post-abortion. The association of gestationis pemphigoid with choriocarcinoma is extremely rare. We report this association in a patient of 35 years in which the diagnosis of gestationis pemphigoid was made on clinical, histological and immunological criteria, and the one of choriocarcinoma was made on clinical, biological radiological and histological criteria. Through this article, we put the item on this association reported for the first time in post-abortion.

Pemphigoid gestationis

We present a 21-year-old primigravida woman with a several-week history of pruritic, edematous, targetoid plaques that appeared initially on the abdomen, flanks, and legs and that progressed to involve the inner aspects of the upper arms and lateral aspects of the chest. The histopathologic findings showed perivascular and interstitial dermatitis with eosinophils and vacuolar changes with linear C3 deposition at the basement-membrane zone on direct immunofluorescence study. A diagnosis of pemphigoid gestationis was made. Pemphigoid gestationis is a rare, bullous dermatosis of pregnancy that may be associated with prematurity and small-for-gestational age birth weights. The diagnosis is often made with direct immunofluorescence studies of perilesional skin. Oral glucocorticoids remain the gold standard of therapy in moderate-to-severe cases. The edematous papules and plaques of pemphigoid gestationis may be particularly difficult to distinguish from polymorphic eruption of pregnancy; therefore, immunofluorescence studies are prudent. Prompt recognition and appropriate management may reduce morbidity of this disease, which often recurs with subsequent pregnancies.

Pemphigoid gestationis: a retrospective study in southwest Iran

Pemphigoid gestationis (PG) is a rare autoimmune bullous dermatosis of pregnancy usually presents in the second or third trimester. It is characterized by pruritic, urticarial plaques with the development of tense vesicles and bullae within the lesions. Pathogenesis of PG is not fully established, however, most patients develop circulating autoantibodies targeting the bullous pemphigoid (BP) 180 antigen. The aim of this work is to draw a profile of the epidemiology, clinical aspects, treatment and evolution of the disease by studying hospital series. We retrospectively investigated the 13 patients who were diagnosed with PG based on hospital data at the Referral Center of Southwest Iran located in Ahvaz city between March 2002 and March 2011. The age of onset was 21 to 40 years (mean age: 27.5 years). The onset of the disease occurred in the second trimester of pregnancy in 6 patients and in the third trimester of pregnancy in 4 patients. One patient had a flare up of disease during the first trimester and two out of cases in puerperium period. In all cases, pruritus was the first symptom, followed by an erythematous vesiculobullous eruption.  The diagnosis of PG was confirmed by skin biopsy. Ten out of the patients treated with oral corticosteroids (0.5-1 mg/kg/day), one of the patients underwent oral corticosteroids plus topical glucocorticoid and the last patient treated with topical glucocorticoid. PG remains a rare dermatosis of pregnancy. Our series had two particularities compared to other studies: high frequency in primigravida and the frequent involvement of the face. Additionally our study demonstrated that improvement could occur faster and provide acceptable management if the treatment of the patients would be implemented sooner.

[Gestational pemphigoid]

Gestational pemphigoid is a rare pruritic bullous pregnancy associated dermatosis caused by autoantibodies against placental and dermal collagen XVII. Clinically, it is characterized by severe pruritus and blisters on abdominal skin and extremities. Immunofluorescence analysis of perilesional skin is used in the diagnostics and maternal serum BP180-levels reflect the disease activity. Topical steroids and antihistamins usually relieve mild symptoms, but in severe cases oral corticosteroid is the drug-of-choice. Spontaneous recovery is common after parturition but this disease typically recurs in the following pregnancies. Due to the associated risk of prematurity and fetal growth restriction, prenatal monitoring jointly by a dermatologist and an obstetrician is recommended.

[Rituximab (Mabthera) for treatment of rare autoimmune bullous skin disorders]

Autoimmune bullous skin disorders are characterized by a severe and potentially lethal course and may require aggressive long-term treatment with systemic corticosteroids and other immunosuppressive drugs, which can lead to serious adverse events. Recently, anti-CD20 antibody, Rituximab, was reported to be beneficial as an adjuvant therapy in these diseases. Herein, we present 2 case reports of patients suffering from resistant rare diseases from the aforementioned spectrum: linear IgA dermatosis and Pemphigoid gestationis. The patients were successfully treated with Rituximab (Mabthera). This is one of the first reports of this kind of treatment for these rare life-threatening diseases. These case reports emphasize the role of Rituximab as a crisis therapy in autoimmune blistering diseases.

Glucocorticosteroid-resistant pemphigoid gestationis: successful treatment with adjuvant immunoadsorption

A 40-year old prima para presented with multiple urticaria-like plaques and severe pruritus 2 weeks prior to giving birth by cesarean section. Three days after birth, the disease flared up and tense blisters appeared on hands, lower arms and feet. Based on the clinical presentation, direct immunofluorescence microscopy, complement binding test and detection of high levels of circulating anti-BP180 antibodies, the diagnosis of pemphigoid gestationis was established. Despite treatment with class IV topical corticosteroid and prednisolone p.o. up to 60 mg/day, both skin lesions and severe pruritus progressed accompanied by increasing anti-BP180 antibody serum levels. In order to continue breast feeding, the prednisolone dose could not be further increased and 10 immunoadsorptions over 4 weeks were performed. During this period, skin lesions cleared rapidly, pruritus subsided and BP180-specific serum autoantibodies decreased by 99.5% allowing the reduction of prednisolone to 7.5 mg/day. We conclude that immunoadsorption is an effective and safe adjuvant therapeutic option for severe pemphigoid gestationis.

[Pemphigoid gestationis: a review]

BACKGROUND

Pemphigoid gestationis (PG) is a rare auto-immune bullous disease occurring in one pregnant woman over 20,000 to 50,000.

OBJECTIVE

Review of literature about physiopathology, immunological diagnosis and treatment of PG.

METHODS

Research on Medline and Embase database without any time limit until April 2010. Because of the lack of randomized therapeutic trials in PG, retrospective series and case reports have been analyzed.

RESULTS

PG is due to auto-antibodies directed against BP180 secondary to a mother-fetus immunological tolerance breaking. Blister formation results from a complex mechanism involving TH2 lymphocytes, cytokines and polymorphonuclear cells. Clinically, the disease is characterized by a pruritic, more or less extensive erythemato-papulous eruption. The presence of vesicles and/or blisters is inconstant but evocative. Recovery occurs generally in a few weeks after delivery but relapses are frequent in subsequent pregnancies. Combined oral contraception may also trigger flares of the disease. Diagnosis is confirmed by direct immunofluorescence showing linear C3±IgG deposits in the dermal-epidermal junction. ELISA BP180-NC16A method is very sensitive to detect circulating auto-antibodies. Fetal prognosis is good, but early onset in 1(st) or 2(nd) trimester and blister formation are risk factors for prematurity and low birth weight. Rarely the newborn may be affected by very transitory blisters. Efficiency of very potent topical corticosteroids has been showed in several studies, and they may be used as first-intent treatment in moderate forms of PG. Systemic corticosteroids are indicated in extensive forms. In very exceptional chronic or relapsing PG, immunosuppressant agents may be necessary.

CONCLUSION

In the absence of consensus between moderate and severe forms of the disease, precise modalities of the steroid treatment (topical or systemic, duration and rhythm of decrease) are not well defined.

[Long-term response to rituximab in a patient with acquired hemophilia]

A 28 year-old female without history of previous disease. In the seventh month of her first pregnancy she developed hemorrhagic tendency that worsened in the early postpartum period. Activated partial thromboplastin time was 110 sec (control=35.8 sec) with negative tests for lupus anticoagulant. Factor VIII was <1% and a factor VIII inhibitor titer was 84 Bethesda Units/mL (BU). Initial therapy included methylprednisolone, prednisone, and cyclophosphamide. After two weeks of treatment, clinical conditions of the patient improved slightly and she was discharged. Outpatient therapy included azathioprine, and prednisone for a period of 22 months but in-hospital management was several times required. We initiated rituximab 375 mg/m2/week/4 weeks. A clinical improvement and increased levels of factors VIII and XI were observed 10 weeks later and factor VIII inhibitor decreased to undetectable levels. After a 82-month follow-up period (since the first rituximab infusion), she is asymptomatic and factor VIII and factor XI plasma levels are 70% and 94%, respectively FVIII inhibitor level is still undetectable. Rituximab seems an alternative for the treatment of acquired hemophilia refractory to standard treatment.

Pemphigoid gestationis

Pemphigoid gestationis is a rare autoimmune blistering disease of pregnancy. It is characterized by pruritic, urticarial plaques with the development of tense vesicles and bullae within the lesions. Pemphigoid gestationis has been associated with premature delivery, small-for-gestational-age infants. Recurrences with subsequent pregnancies are often more severe. Oral glucocorticoids are the mainstay of therapy. Differentiation of pemphigoid gestationis from pruritic urticarial papules and plaques of pregnancy is essential because management and outcomes differ. In instances in which clinical diagnosis is difficult, direct immunofluorescence tests, immunoblots, or ELISA studies of anti-basement-membrane zone antibodies are useful in establishing the diagnosis.

IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis

BACKGROUND

Patients with bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and pemphigoid gestationis (PG) have IgG antibodies against BP180 and BP230, components of the hemidesmosomes. Patients with linear IgA bullous dermatosis (LABD) have IgA autoantibodies against a 97/120-kDa protein which is highly homologous to a shedded fragment of the BP180-ectodomain.

OBJECTIVES

The aim of our study was to determine the incidence of IgA autoantibodies directed against BP180/BP230 in the pemphigoids and LABD and to determine the antigenic regions that are targeted by IgA autoantibodies.

METHODS

Utilizing baculovirus-expressed recombinant BP180 and BP230 proteins, we performed immunoblot analyses for IgA reactivity of sera from patients with BP (n = 30), MMP (n = 10), PG (n = 6), LABD (n = 6) and from control patients with non-related pruritic dermatoses (n = 8).

RESULTS

IgA reactivity against BP180 and/or BP230 was detected in 19/30 of the BP, in 7/10 of the MMP, in 6/6 of the LABD and in 3/6 of the PG sera, respectively, but not in the control group. In all subgroups, the major antigenic site recognized by IgA antibodies was located within the NH(2)-terminus of the BP180-ectodomain, but only a minority of the sera showed also IgA reactivity against the BP180-NC16a-domain. IgA reactivity against the central domain of BP180 was more frequently seen than against its COOH-terminus. IgA against the COOH- and NH(2)-terminus of BP230, respectively, was detected in 6/30 of the BP, 1/10 of the MMP, 1/6 of the LABD and 0/8 control sera.

CONCLUSION

IgA reactivity against BP180 and/or BP230 is a common finding in the pemphigoids.

Pregnant women have increased incidence of IgE autoantibodies reactive with the skin and placental antigen BP180 (type XVII collagen)

BP180 (type XVII collagen) is a transmembrane protein expressed in a variety of cell types. It is also the target of autoantibodies in cutaneous autoimmune disease including bullous pemphigoid and pemphigoid gestationis, a disease unique to pregnancy. The purpose of this study was to determine the prevalence and specificity of cutaneous autoantibodies in a cohort of pregnant women. De-identified sera were collected from pregnant women (n=299) and from non-pregnant controls (n=134). Sera were analyzed by ELISA for the presence of IgG and IgE autoantibodies directed against several cutaneous autoantigens. IgE antibodies against the NC16A domain of BP180 were detected in 7.7% of pregnant women, compared to 2.2% of healthy controls (p=0.01). No increase in total or cutaneous autoantigen specific IgG was seen. Total serum IgE was within the normal range. Full-length BP180 was detected by western immunoblot in epidermal, keratinocyte, placental and cytotrophoblast (CTB) cell lysates. Furthermore, flow cytometry and indirect immunofluorescence confirmed the expression of BP180 on the surface of cultured CTBs. Finally, it was demonstrated that IgE antibodies in the pregnancy sera labeled not only cultured CTBs, but also the placental amnion and cutaneous basement membrane zone using indirect immunofluorescence. We conclude that some pregnant women develop antibodies specific for BP180, and that these autoantibodies are capable of binding both CTB and the placental amnion, potentially affecting placental function.

[Diagnostic image. A woman in childbed with itch and vesicles]

A 37-year-old woman in childbed developed gestational pemphigoid.

Pemphigoid gestationis: clinical and laboratory evaluation

INTRODUCTION

Pemphigoid gestationis, also known as herpes gestationis, is a rare autoimmune blistering disease associated with pregnancy. It usually occurs during the second or third trimester, but it may be present at any stage of pregnancy or the puerperium. The clinical, histologic, and immunopathological features of pemphigoid gestationis are similar to those of the pemphigoid group of disorders.

METHODS

We hereby report seven patients who were diagnosed with pemphigoid gestationis and followed at the Autoimmune Blistering Disease Clinic in the Department of Dermatology of the University of Sao Paulo Medical School between 1996 and 2008.

DISCUSSION

Demographic and clinical findings, such as median age, sites of involvement, and gestational age of onset or C3 of our patients, coincide with those described in previous reports. The majority of patients (85%) exhibited complement C(3) and immunoglobulin G (IgG) deposition along the basement membrane zone (BMZ) on immunofluorescence. Herpes gestationis factor (HG) factor was postitive in four out of six patients (67%), and three out of five patients recognized the bullous pemphigoid recombinant antigen (BP180) by ELISA.

CONCLUSION

This study revealed a good outcome of the newborns from pemphigoid gestationis affected mothers, based on the absence of pemphigoid gestationis cutaneous lesions, mean birth weight, and normal Apgar scores and gestational age at birth.

Enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence testing in a bullous pemphigoid and pemphigoid gestationis

Enzyme-linked immunosorbent assay (ELISA) is an excellent tool for detection of circulating antibodies against the NC16A portion of BP180 antigen. We compared the sensitivity and specificity of a commercially available BP180-NC16a domain ELISA with that of an indirect immunofluorescence (IIF) testing in the evaluation of bullous pemphigoid (BP) and pemphigoid gestationis (PG), and analyzed the relationship between ELISA results and the presence of IgG deposition, in an epidermal or combined pattern, on direct immunofluorescence (DIF) testing of salt-split skin. ELISA was performed on serum from 28 patients (24 BP, 4 PG) and 50 controls. IIF testing was performed on serum from 27 patients and 98 controls. For the group of 28 patients with BP or PG, ELISA had a sensitivity of 93% and specificity of 96% (P < 0.001), while sensitivity was 74% and specificity 96% (P < 0.001) for IIF testing. In these patients, ELISA has a higher sensitivity than IIF testing, but similar specificity. Evaluation of controls who had IgG deposition on the dermal side of salt-split skin on DIF testing showed specificity for the ELISA of 100% (all four cases negative) and 80% for IIF testing (one of five positive). Positive ELISA correlated with a diagnosis of BP or PG only in patients who had IgG at the basement membrane zone (BMZ) by DIF testing. Overall, ELISA appears to have greater sensitivity and specificity for BP or PG than does IIF testing.

Pemphigoid gestationis autoantigen, transmembrane collagen XVII, promotes the migration of cytotrophoblastic cells of placenta and is a structural component of fetal membranes

In pemphigoid gestationis (PG), autoantibodies target collagen XVII, a hemidesmosomal transmembrane protein, which is an important element in cutaneous epithelial adhesion and signalling. We report that collagen XVII is expressed in the first trimester and term syncytial and cytotrophoblastic cells of normal placenta and in epithelial cells of amniotic membrane. Immunoelectron microscopy confirmed the localization of collagen XVII to the hemidesmosomes of amniotic epithelium. Examination of three PG placentas showed mild villitis, but there were no differences between collagen XVII expression levels or immunostaining signals as compared to normal placenta. Collagen XVII expression was also detected in cultured extravillous trophoblast HTR-8/SVneo cells, where collagen XVII expression was upregulated by PMA and TGF-beta1. Interestingly, the presence of Col15, the cell migration domain of collagen XVII, induced the migration of HTR-8/SVneo cells in transmigration assay. Analysis of amniotic fluid samples at different gestational weeks revealed that a large quantity of collagen XVII ectodomain was shed into amniotic fluid throughout pregnancy. Biochemical and immunoblotting analysis indicated that the ectodomain in amniotic fluid is structurally very similar to the ectodomain produced by cultured keratinocytes. Cultured cells from amniotic fluid samples also expressed collagen XVII. Our results suggest that collagen XVII may contribute to the invasion of extravillous trophoblasts during placental development and is also required for the integrity of amniotic basement membrane. Although the exact pathomechanism of PG is still largely unknown, the clinical symptoms of PG are initiated after the expression of collagen XVII in placenta during the first trimester of pregnancy.

Herpes gestationis in a mother and newborn: immunoclinical perspectives based on a weekly follow-up of the enzyme-linked immunosorbent assay index of a bullous pemphigoid antigen noncollagenous domain

BACKGROUND

Herpes gestationis (HG) is a rare, autoimmune, bullous disease that occurs during the second or third trimester and usually resolves over weeks or months after delivery. Neonates with HG are rare (estimated at 1 per 100,000 cases). Although anti-180-kDa bullous pemphigoid (BP180) autoantibody and transfer of this autoantibody are known as the cause, to our knowledge, no coordinated analysis of clinical symptoms and anti-BP180 antibody enzyme-linked immunosorbent assay titers has been reported in a mother and neonate with HG.

OBSERVATIONS

We describe a 33-year-old woman with HG and her neonate with vesicular erythematous lesions and the weekly follow-up results of the BP180 noncollagenous domain (NC16a) enzyme-linked immunosorbent assay.

CONCLUSIONS

Almost the same titer of pathogenic antibody as that in the mother is transferred to the neonate. The plasma elimination half-life of anti-BP180 antibody is approximately 15 days in mother and neonate. An abrupt twin peak increase in the BP180 enzyme-linked immunosorbent assay index from maternal serum was observed just before and after delivery, possibly explaining why HG usually occurs in the last trimester of pregnancy and exacerbates postpartum. Lesions in the neonate resolve without treatment far before pathogenic antibody disappears, suggesting that factors other than anti-BP180 antibodies may be involved in the generation of eruptions. Frequent testing of the BP180 enzyme-linked immunosorbent assay greatly facilitates therapeutic planning.

Enzyme-linked immunosorbent assay using multimers of the 16th non-collagenous domain of the BP180 antigen for sensitive and specific detection of pemphigoid autoantibodies

Bullous pemphigoid (BP) and pemphigoid gestationis (PG) are acquired autoimmune subepidermal blistering diseases characterized by autoantibodies against the hemidesmosomal proteins BP180/type XVII collagen and BP230. In the vast majority of BP and PG patients, these autoantibodies bind to epitopes clustered within the 16th non-collagenous domain of BP180. An ELISA system for the detection of these autoantibodies was developed and evaluated using 16th non-collagenous domain (NC16A) tetramers instead of monomers. In contrast to antigens fused to large proteins used in the past for the detection of autoantibodies against type XVII collagen, tetrameric antigen fragments bearing a small hexahistidine tag allow for high expression levels without the need to cleave off the fusion partner. Using tetrameric BP180 NC16A, positive reactions were found in 106 (89.8%) of 118 randomly selected BP sera and in all of 20 (100%) randomly selected PG sera, whereas only 2.2% of a large cohort of control subjects were positive in this assay, including patients with rheumatoid arthritis (two of 107), progressive systemic sclerosis (two of 50), systemic lupus erythematosus (one of 72), and healthy blood donors (10 of 494). Thus, the sensitivity and specificity of the new anti-tetrameric NC16A ELISA were 89.9% and 97.8% respectively. Levels of circulating autoantibodies against BP180 paralleled disease activity in the pemphigoid patients. In conclusion, the use of tetrameric NC16A in ELISA results in a sensitive and specific tool for diagnosis and monitoring of BP and PG.

The intracellular and extracellular domains of BP180 antigen comprise novel epitopes targeted by pemphigoid gestationis autoantibodies

Pemphigoid gestationis (PG) is an autoimmune sub-epidermal bullous dermatosis of pregnancy associated with circulating autoantibodies targeting the extracellular non-collagenous (NC) 16A domain of bullous pemphigoid (BP) 180 antigen. In order to determine whether BP180 regions other than NC16A are recognized by PG autoantibodies, we have analyzed the reactivity of 15 PG patient sera against several BP180 antigenic sites by sensitive methods such as immunological screening and ELISA. Most PG sera tested (13 of 15) reacted with an epitope (amino acid 508-541) mapped in the NC16A domain. Of note, nine of 15 PG patient sera reacted with at least one additional antigenic site other than NC16A. Specifically, two epitopes in the BP180 extracellular domain and five epitopes in the intracellular one were recognized by three and seven PG sera, respectively. In addition, a representative intracellular epitope was recognized by PG autoantibodies as a portion of BP180 antigen both in denaturating and native conditions. Finally, reactivity against epitopes additional to NC16A was also detected at an early stage of the disease. The identification and characterization of hitherto unrecognized epitopes targeted by PG patient autoantibodies provide novel insights into the pathophysiology of humoral immune response to BP180 in PG.

IgG4 as the predominant IgG subclass in pemphigoides gestationis

BACKGROUND

Pemphigoides gestationis (PG) is a blistering disorder of pregnancy caused by antibodies against basement membrane proteins. They are directed against the 180 kD bullous pemphigoid antigen (BPAg2), towards the epitopes within the NC 16A domain. There are many similarities between pemphigoid gestationis and bullous pemphigoid (BP), but the literature so far indicated different immunofluorescence results in regards with C3 and IgG, and IgG subclasses (IgG4 vs. IgG1).

METHODS

We evaluated staining patterns and IgG subclasses, as well as C5b-9 membrane attack complex (MAC) in 10 pregnant patients with PG, using sandwich double antibody immunofluorescence (SDAI) and direct immunofluorescence (DIF).

RESULTS

All ten specimens stained with C3 by DIF, but only five had trace amount of IgG reactants by this method. By SDAI, 100% were positive for the IgG4 and C5b-9 MAC, 70% for IgG2, 50% for IgG1, and 40% for IgG3.

CONCLUSION

IgG4 was the predominant IgG subtype identified. This finding has not been reported for PG, but it mimics results reported for BP. One explanation is prolonged disease course, as well as blocking of antigenic domains by IgG4. Understanding this completely will help develop therapies and prevention strategies for immunobullous and other autoimmune diseases, and perhaps aid in an exact classification.

Immunoadsorption against two distinct epitopes on human type XVII collagen abolishes dermal-epidermal separation induced in vitro by autoantibodies from pemphigoid gestationis patients

Pemphigoid gestationis (PG) is a subepidermal autoimmune blistering disease characterized by self-reactive T and B cells specific for the transmembrane hemidesmosomal protein type XVII collagen/BP180. Major T and B cell epitopes are located within the immunodominant 16th non-collagenous domain A (NC16A) of type XVII collagen. The aim of the present study was to map the pathogenically relevant epitopes targeted by blister-inducing patients' autoantibodies. For this purpose, we used an in vitro model of autoantibody-induced leukocyte-dependent dermal-epidermal separation. Pre-adsorption against a recombinant form of the NC16A region abolished the blister-inducing potential of autoantibodies from all PG patients. Using overlapping synthetic peptides, we demonstrated that PG autoantibodies bind to two defined epitopes within the NC16A region (aa 500-514 and aa 511-523). Importantly, pre-adsorption using an affinity matrix containing these epitopes completely abolished dermal-epidermal separation induced by PG autoantibodies. This study identifies the epitopes relevant for blister induction in PG and should facilitate the development of an antigen-specific immunoadsorption therapy for this disease.

Immunological aspects of pregnancy

Alterations to the immune status of the pregnant woman are necessary to allow mothers to tolerate genetically different fetal tissues during pregnancy. These alterations lead to impaired cell-mediated immunity with increased susceptibility to certain infections such as tuberculosis. During pregnancy, the maternal immune system also shows a relative bias toward T helper type 2 immunity. Several inflammatory dermatoses are either unique to pregnancy or altered by the pregnant state. Immunologists are now beginning to understand the various factors that contribute to the maternal immune tolerance and, in particular, the role of classic (human leukocyte antigen [HLA]-A, HLA-B, HLA-C, and HLA-D) and non-classic (HLA-E, HLA-F, and HLA-G) major histocompatability antigens in this process. Human leukocyte antigen-G, in particular, seems to be important in protecting HLA mismatched tissue from the innate immune system, and investigation of HLA-G expression may help to explain how pregnancy affects inflammatory skin disease. Immunologists are now beginning to understand the alterations to the immune status of the pregnant woman that are necessary to allow mothers to tolerate genetically different fetal tissues during pregnancy. These alterations may help to explain how pregnancy effects inflammatory skin disease.

Pemphigoid gestationis with predominant involvement of oral mucous membranes and IgA autoantibodies targeting the C-terminus of BP180

Pemphigoid gestationis (PG) is an autoimmune pregnancy-associated subepidermal blistering disease. It usually affects skin and, rarely, mucous membranes. In the vast majority of patients with PG, the autoimmune response is directed to the membrane-proximal NC16A domain of the 180-kd bullous pemphigoid (BP) antigen (BP180) and is mediated by IgG1 and IgG3 autoantibodies. We report the case of a patient with PG associated with extensive lesions on oral mucous membranes. Immunoblotting studies demonstrated the presence of circulating IgA autoantibodies in the patient's serum that were exclusively directed to a 49 amino acid stretch on the C-terminal portion of the BP180 ectodomain located 800 amino acids downstream from NC16A. This C-terminal stretch of BP180 has previously been demonstrated to localize to the lamina lucida/lamina densa interface and to be recognized by IgG and IgA antibodies in a subgroup of patients with cicatricial pemphigoid as well as by IgG autoantibodies in some BP sera. Our patient's lesions healed without scarring within 6 weeks after delivery of a healthy child. The findings in this patient extend the clinical and immunopathologic spectrum of PG.

Cicatricial pemphigoid differs from bullous pemphigoid and pemphigoid gestationis regarding the fine specificity of autoantibodies to the BP180 NC16A domain

Bullous pemphigoid (BP), pemphigoid (herpes) gestationis (PG), cicatricial pemphigoid (CP), and lichen planus pemphigoides (LPP) are autoimmune subepidermal bullous diseases that are characterized by circulating autoantibodies to the transmembrane hemidesmosomal protein BP180/type XVII collagen. Previous studies demonstrated that the majority of patients with BP, PG, and LPP show antibodies to an immunodominant, membrane-proximal non-collagenous domain (NC16A) on the extracellular portion of BP180. By the use of non-overlapping peptides of the NC16A domain, we previously demonstrated that autoantibodies from BP and PG patients mainly react with epitopes clustered within the N-terminus of this immunodominant site of BP180; antibodies from patients with LPP also recognized the C-terminal portion of NC16A. However, some of these results had been obtained indirectly by preadsorption studies. The aim of the present study was to analyze the fine specificity of IgG autoantibodies to NC16A in sera from patients with CP and to compare their reactivity with antibodies from BP, PG, and LPP patients using a series of new overlapping fragments covering the entire NC16A domain. We confirm that BP and PG sera mainly react with N-terminal epitopes of NC16A, whereas sera from patients with LPP also bind to C-terminal portions, of this domain. Interestingly, out of ten patients with CP, the sera of seven reacted with NC16A; within NC16A, these sera bound to both C-terminal fragments and an N-terminal epitope right next to the cell membrane. Our data demonstrate a heterogeneous binding pattern of autoantibodies to BP180 NC16A in patients with CP.

Molecular mapping of the major epitopes of BP180 recognized by herpes gestationis autoantibodies

Herpes gestationis (HG) is an autoantibody-mediated subepidermal bullous dermatosis associated with pregnancy. The primary target of HG autoantibodies is BP180, a 180-kDa hemidesmosomal glycoprotein. We previously showed that autoantibodies and autoimmune T lymphocytes from HG patients recognize the MCW-1 antigenic site (AA 507-520), which is located in the membrane-proximal noncollagenous domain (NC16A) of BP180. Here, we analyzed the sera of 37 HG patients to further define the sites on BP180 that are targeted by autoantibodies. All of the HG sera, but none of the control sera, were immunoreactive with sec180e, a 120-kDa recombinant protein encompassing the entire BP180 extracellular domain. HG sera depleted of reactivity to NC16A no longer reacted with sec180e, indicating that the major HG-associated epitopes on BP180 are restricted to the NC16A domain. The vast majority of the HG sera (34 of 37) reacted with a 7 amino acid peptide corresponding to the N-terminal half of MCW-1 (MCW-1A). Eleven HG sera (including the 3 that failed to react with MCW-1A) recognized one or more of three antigenic sites located within a 15 amino acid stretch immediately downstream of MCW-1A. In summary, we have identified four major HG-associated epitopes clustered within a 22 amino acid region of the BP180 ectodomain. These findings support the hypothesis that an autoimmune response to the BP180 NC16A domain is a crucial step in the pathogenesis of HG.

Severe subepidermal blistering disorder with features of bullous pemphigoid and herpes gestationis

Herpes gestationis (HG) and bullous pemphigoid (BP) are blistering disorders with similar features, including urticarial lesions that progress to blisters and immunodeposition of C3 in a linear pattern at the basement membrane zone. Among their differences, HG is distinguished by its association with pregnancy, the puerperium, or hormonal perturbation. We describe the immunopathologic findings and clinical course in a multiparous woman with a severe blistering eruption. The patient was not pregnant. Malignancy evaluation was negative, and hormonal testing was normal. Histologic examination demonstrated a subepidermal bulla with eosinophils. Direct immunofluorescence showed C3 in a strong linear band at the dermal-epidermal junction. Indirect immunofluorescence demonstrated circulating IgG and IgG3 antibodies to basement membrane zone (epidermal component on salt-split skin), and complement-fixing IgG. Immunoprecipitation demonstrated antibodies to a 180-kd keratinocyte protein antigen. By clinical definition, this patient has BP. However, her disease presentation demonstrated features of both BP and HG.

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 alpha/beta TCRs and a CD4 memory T cell phenotype and secreted IFN-gamma 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.