Overlapping IgG4 Responses to Self- and Environmental Antigens in Endemic Pemphigus Foliaceus.

The etiology of human autoimmune diseases in general remains largely unknown, although the genetic and environmental interplay may be relevant. This applies to the autoimmune diseases of the skin such as the pemphigus phenotypes and others. In this group, there is an endemic form of pemphigus foliaceus (also known as fogo selvagem [FS]) in which the pathogenic IgG4 autoantibody response to the self-antigen desmoglein 1 (Dsg1) cross-reacts with the LJM11 sand fly salivary gland Ag. In this investigation, we dissected the IgG4 autoantibody repertoires used by FS patients in response to endogenous self-Dsg1 and exogenous LJM11 sand fly Ag. Based on analyses of the genetic clonal signatures of these Abs, our results indicate that there is a significant overlap between these two responses, as all identified IgG4 mAbs cross-react to both Dsg1 and LJM11 Ags. Germline H- and L-chain V gene Abs generated according to mutated cross-reactive mAbs preserved their reactivity to both Ags. Our findings suggest that both Dsg1 autoantigen and LJM11 environmental Ag could be the initial antigenic stimulants for the IgG4 autoimmune responses in FS. These results support our hypothesis that LJM11 Ag plays a substantial role in triggering the IgG4 autoantibody development in FS and provide new insights on how noninfectious environmental Ag(s) may drive the generation of autoantibodies in IgG4-related autoimmune diseases.

Cutting Edge: Brazilian pemphigus foliaceus anti-desmoglein 1 autoantibodies cross-react with sand fly salivary LJM11 antigen.

The environmental factors that contribute to the development of autoimmune diseases are largely unknown. Endemic pemphigus foliaceus in humans, known as Fogo Selvagem (FS) in Brazil, is mediated by pathogenic IgG4 autoantibodies against desmoglein 1 (Dsg1). Clusters of FS overlap with those of leishmaniasis, a disease transmitted by sand fly (Lutzomyia longipalpis) bites. In this study, we show that salivary Ags from the sand fly, and specifically the LJM11 salivary protein, are recognized by FS Abs. Anti-Dsg1 monoclonal autoantibodies derived from FS patients also cross-react with LJM11. Mice immunized with LJM11 generate anti-Dsg1 Abs. Thus, insect bites may deliver salivary Ags that initiate a cross-reactive IgG4 Ab response in genetically susceptible individuals and lead to subsequent FS. Our findings establish a clear relationship between an environmental, noninfectious Ag and the development of potentially pathogenic autoantibodies in an autoimmune disease.

The role of intramolecular epitope spreading in the pathogenesis of endemic pemphigus foliaceus (fogo selvagem).

We report here a relationship between intramolecular epitope spreading and the clinical onset of the endemic form of pemphigus foliaceus in a Brazilian community with a high prevalence and incidence of the disease. Also known as Fogo Selvagem (FS), this disease is characterized by severe skin blistering and pathogenic anti-desmoglein-1 (Dsg1) autoantibodies. These autoantibodies bind the Dsg1 ectodomain and trigger keratinocyte cell detachment, the hallmark of FS. We show that (a) sera from FS patients in the preclinical stage recognized epitopes on the COOH-terminal EC5 domain of Dsg1, (b) disease onset was associated with the emergence of antibodies specific for epitopes on the NH2-terminal EC1 and EC2 domains, (c) all sera from FS patients with active disease recognized the EC1 and/or EC2 domains, and (d) sera from FS patients in remission showed reactivity restricted to EC5. These results suggest that anti-Dsg1 autoantibodies in FS are initially raised against the COOH-terminal EC5 domain of Dsg1 in individuals without skin disease; in genetically predisposed subjects the autoimmune response may then undergo intramolecular epitope spreading toward epitopes on the NH2-terminal EC1 and EC2 domains of Dsg1 leading to disease onset. Moreover, intramolecular epitope spreading may also modulate remissions and relapses of FS.

A Lutzomyia longipalpis Salivary Protein Induces Cross-Reactive Antibodies to Pemphigus Autoantigen Desmoglein 1.

Fogo selvagem (FS) is a blistering skin disease caused by pathogenic IgG4 autoantibodies to desmoglein 1 (DSG1). Preclinical FS and leishmaniasis are endemic to certain regions of Brazil and exhibit nonpathogenic anti-DSG1 antibodies. Recurring bites from Lutzomyia longipalpis, the sand fly vector of leishmaniasis, immunize individuals with L. longipalpis salivary antigens LJM17 and LJM11. We measured the antibody responses to LJM17, LJM11, and DSG1 in normal settlers and patients with FS from an endemic focus of FS and nonendemic control populations. We also immunized mice with these antigens and assessed the IgG response. Healthy individuals and patients with FS from endemic areas had significantly higher values of IgG4 anti-LJM17 antibodies than nonendemic controls (P < 0.001 for both). The levels of IgG anti-DSG1 and IgG4 anti-LJM17 and anti-LJM11 antibodies correlated positively in normal settlers and patients with FS. Mice immunized with recombinant LJM17 produced IgG1 antibodies (human IgG4 homolog) that strongly cross-reacted with recombinant DSG1; these IgG1 antibodies were inhibited by LJM17, LJM11, and DSG1 in a dose-dependent manner. However, they did not bind human or mouse epidermis by indirect immunofluorescence. Lastly, we identified short-sequence homologies of surface-exposed residues within the human DSG1 ectodomain and LJM17. Inoculation by LJM17 from L. longipalpis-elicited DSG1-cross-reactive IgG4 antibodies may lead to FS in genetically predisposed individuals.

Endemic pemphigus vulgaris.

BACKGROUND: Investigators from Brasilia, Brazil, observed several patients with a mucocutaneous disease that resembles pemphigus vulgaris clinically and histologically but with epidemiological features of fogo selvagem. Our objective was to characterize antidesmoglein 3 and antidesmoglein 1 autoantibody profiles in these unique patients who reside in Goiânia and Brasilia, Brazil, known endemic regions of fogo selvagem. OBSERVATIONS: We performed serological evaluation of 8 patients with a mucocutaneous disease clinically and histologically consistent with pemphigus vulgaris, as well as 27 healthy relatives of patients with fogo selvagem who reside in these endemic areas. Serum samples from all 8 patients bound desmoglein 3 by cold immunoprecipitation and from 6 patients by enzyme-linked immunosorbent assay, while serum samples from 4 patients bound desmoglein 1 by cold immunoprecipitation and by enzyme-linked immunosorbent assay. Antidesmoglein 3 autoantibodies were detected in 4 of 27 healthy donors by cold immunoprecipitation and by enzyme-linked immunosorbent assay, whereas antidesmoglein 1 autoantibodies were detected in 6 individuals by cold immunoprecipitation and in 3 individuals by enzyme-linked immunosorbent assay. CONCLUSION: These findings provide serological evidence of a new endemic variant of pemphigus vulgaris.

Divergent Specificity Development of IgG1 and IgG4 Autoantibodies in Endemic Pemphigus Foliaceus (Fogo Selvagem).

We have shown that although the IgG response in fogo selvagem (FS) is mainly restricted to desmoglein (Dsg) 1, other keratinocyte cadherins are also targeted by FS patients and healthy control subjects living in the endemic region of Limão Verde, Brazil (endemic controls). Evaluating nonpathogenic IgG1 and pathogenic IgG4 subclass responses to desmosomal proteins may reveal important differences between pathogenic and nonpathogenic responses, and how these differences relate to the pathogenic IgG4 response and resultant FS. In this study, we tested by ELISA >100 sera from each FS patient, endemic control, and nonendemic control for IgG1 and IgG4 autoantibodies to keratinocyte cadherins besides Dsg1. IgG1 and IgG4 subclass responses in endemic controls are highly correlated between Dsg1 and other keratinocyte cadherins. This correlation persists in the IgG1 response among FS patients, but diminishes in IgG4 response, suggesting that IgG1 binds highly conserved linear epitopes among cadherins, whereas IgG4 binds mainly specific conformational epitopes on Dsg1. A confirmatory test comparing serum samples of 11 individuals before and after their FS onset substantiated our findings that IgG1 recognizes primarily linear epitopes on Dsg1 both before and after disease onset, whereas IgG4 recognizes primarily linear epitopes before disease onset, but recognizes more conformational epitopes on Dsg1 after the onset of disease. This study may provide a mechanism by which a specificity convergence of the IgG4 response to unique Dsg1 epitopes, most likely conformational pathogenic epitopes, leads to the onset of FS disease.

Prevalence of anti-desmoglein-3 antibodies in endemic regions of Fogo selvagem in Brazil.

Fogo selvagem (FS), the endemic form of pemphigus foliaceus (PF), is an autoimmune blistering disease characterized by autoantibodies against desmoglein 1. The Terena reservation of Limao Verde in Mato Grosso do Sul, Brazil, is a previously identified focus of disease. Autoantibodies against desmoglein 3 (Dsg3) have also been detected in sera from patients with FS. In an effort to further characterize the serological, geographical, and clinical epidemiology of the disease, we sought to determine the prevalence of anti-Dsg3 autoantibodies in sera from normal subjects living outside of and in an endemic area using an ELISA. Anti-Dsg3 antibodies were detected in 53 of 146 normal subjects from Limao Verde (36%), and in eight of 140 normal subjects from surrounding areas (6%). A significant trend was observed in the proportion of positive tests relative to distance from the endemic area (P < 0.001). Our seroepidemiological observations support the concept that the likely environmental trigger of the antibody response in FS is located in this endemic area, and that the population at risk to develop FS may also be at risk to develop an endemic form of pemphigus vulgaris as reported by our co-investigators from Brasilia.

Paraneoplastic pemphigus associated with pelvic inflammatory fibrosarcoma: a case report.

A 36-year-old African-American woman presented with an extensive stomatitis and pigmented cutaneous macules on the neck, axillae and hands. Subsequently she developed violaceus papules on the dorsa of the hands, histologically consistent with an interface dermatitis. After 18 months of progressive disease, paraneoplastic pemphigus was suspected and a search for an underlying neoplasm was initiated. An exploratory laparotomy revealed a pelvic mass and the histologic examination showed an inflammatory fibrosarcoma. The evidence of acantholysis on new cutaneous lesions and the positivity of indirect immunofluorescence with rodent urinary bladder epithelium reinforced the diagnostic criteria for paraneoplastic pemphigus, which is confirmed by the identification of strong protein bands at 210, 190 and 170 kd by immunoprecipitation. Paraneoplastic pemphigus should be considered when investigating atypical mucocutaneous manifestations of pemphigus vulgaris and lichen planus. Diagnostic screening for paraneoplastic pemphigus and a search for an underlying tumor should be performed.

Update on fogo selvagem, an endemic form of pemphigus foliaceus.

Pemphigus are organ-specific autoimmune diseases, where autoantibodies (mainly immunoglobulin [Ig]G) directed against epidermal targets (glycoproteins of the desmosomal core) are detected. Endemic pemphigus foliaceus or fogo selvagem (FS) is one of the variants of pemphigus foliaceus pemphigus foliaceus that shares the same clinical and immunopathological features of the classic non-endemic pemphigus foliaceus form, including pathogenic IgG (mainly IgG4) autoantibodies directed against the ectodomain of desmoglein 1 (Dsg1), that lead to acantholysis. Pathogenesis of FS is complex, involving genetic, environmental and immunological factors. Human leukocyte antigen (HLA)-DRB1 alleles DRB1*0404, *1402, *1406 or *0102 have been previously identified as risk factors for FS (relative risk, >14). Individuals exposed to hematophagous insects are more susceptible to develop the disease. Non-pathogenic anti-Dsg1 antibodies of the IgG1 subclass, directed against the extracellular 5 domain of Dsg1, are detected in patients in the preclinical stage of the disease, and also in healthy controls living in endemic areas. In counterpart, patients with FS show pathogenic anti-Dsg1 IgG4 autoantibodies that bind the pathogenic extracellular 1 and 2 domains of Dsg1, emphasizing the intramolecular epitope-spreading hypothesis. A possible explanation for the development of the autoimmune process would be antigenic mimicry, initiated by environmental stimuli in those genetically predisposed individuals. Characterization of the pathogenesis of FS will allow the development of specific therapeutic targets, and the elucidation of other autoimmune processes.

Anti-desmoglein-1 antibodies in onchocerciasis, leishmaniasis and Chagas disease suggest a possible etiological link to Fogo selvagem.

Pemphigus foliaceus (PF) and the endemic form Fogo Selvagem (FS) are mediated by pathogenic antibodies to the EC1-2 domains of desmoglein-1. There is a preclinical phase with antibodies to only EC5. Based on geographic clustering of cases, FS is thought to have an, as yet unidentified, environmental trigger. In this study we have searched for anti-desmoglein-1 antibodies in sera from parasitic (leishmaniasis, Chagas, and onchocerciasis), and infectious diseases (leprosy and South American (SA) blastomycosis), which are prevalent in the same geographic regions of Brazil as FS. A specific and sensitive desmoglein-1 ELISA detected antibodies in 34 of 41 onchocerciasis (83%), 38 of 88 leishmaniasis (43%), 18 of 31 Chagas disease (58%), 7 of 28 SA blastomycosis (25%), and 14 of 83 leprosy sera (17%). These sera recognized epitopes restricted to the EC5 domain. These findings identify several etiological factors for FS. It is hypothesized that a component of insect vector saliva, rather than the parasite itself may trigger an antibody response to EC-5. In persons with the known HLA susceptibility alleles and living in endemic areas, a response to the EC1-2 domains may subsequently develop by epitope spreading with associated clinical signs of FS.

Pemphigus foliaceus with neutrophilic spongiosis evolving to an atypical pemphigus phenotype.

A 46-year-old Brazilian man, with initial pustular lesions, neutrophilic spongiosis and subcorneal cleavage evolved to an atypical pemphigus phenotype, with suprabasal acantholysis. Interestingly, his autoantibody profile, tested by immunofluorescence, immunoblotting, enzyme-linked immunosorbent assay, and immunoprecipitation revealed exclusive IgG anti-desmoglein 1 antibodies in all phases of the disease.

Two Brazilian cases of IgA pemphigus.

IgA pemphigus is a rare, neutrophilic, acantholytic skin disorder with approximately 70 cases described in the literature. We report two patients with the subcorneal pustular dermatosis (SPD) type of IgA pemphigus. Initially, both patients were misdiagnosed as subcorneal pustular dermatosis of Sneddon and Wilkinson. The correct diagnosis was only made after detecting intercellular IgA depositions in the epidermis by direct immunofluorescence. Immunoblotting (IB) of normal human epidermal extracts, performed on both sera, was negative for Dsg 1, Dsg 3, BP 230, BP 180, 210 kDa envoplakin, and 190 kDa periplakin. ELISA for desmogleins (Dsg 1 and Dsg 3) showed that neither of the cases had IgA antibodies to Dsg. The c-DNA transfection test for desmocollins (Dsc) revealed that the IgA antibodies of both patients reacted with desmocollin 1. This result supports the hypothesis that the autoantigen in SPD type IgA pemphigus is desmocollin 1.

Epidermolysis bullosa acquisita in childhood.

Epidermolysis bullosa acquisita (EBA) is a subepidermal autoimmune blistering disease that is rarely reported in childhood. We describe a nine-month-old mulatto boy presenting with multiple, annular, widespread, tense blisters and oral lesions. The diagnosis of EBA was confirmed by histopathology, immunofluorescence, and immunoblotting analysis. The patient was successfully treated with systemic steroids (prednisone) and dapsone. After 20 months of initial treatment, clinical remission was observed, and dapsone remains as the current treatment. This case report emphasizes the rarity of EBA in childhood and the difficulties in reaching the final diagnosis.

Disseminated cytomegalovirus disease as a cause of prolonged fever in a bullous pemphigoid patient under systemic steroid therapy.

We present the first reported case of disseminated cytomegalovirus (CMV) in association with prednisone therapy in bullous pemphigoid (BP). A 66-year-old black male patient was admitted to our hospital presenting cutaneous pruritic lesions represented by tense blisters, with serous content on the arms, abdomen and legs. Laboratory findings confirmed the diagnosis of BP. After two weeks of prednisone therapy, the patient developed prolonged fever, which was caused by CMV disseminated disease, with prompt clinical recovery after ganciclovir administration.

Analysis of Anti-desmoglein 1 Autoantibodies in 68 Healthy Mother/Neonate Pairs from a Highly Endemic Region of Fogo Selvagem in Brazil.

OBJECTIVES: Fogo Selvagem (FS) in Limao Verde (LV), Brazil shows clinical and histological features of pemphigus foliaceus (PF) and shares pathogenic IgG4 anti-desmoglein 1 (Dsg1) autoantibodies. Previously, our group reported that mothers with active FS deliver babies with normal skin and low/negative titers of IgG4 autoantibodies by indirect immunofluorescence. It was postulated that maternal pathogenic IgG4 autoantibodies do not cross the placenta due to differential receptor mediated transplacental passage of IgG subclasses. It was also thought that placental Dsg1 may immunoadsorb pathogenic autoantibodies from the mother; hence pathogenic IgG4 autoantibodies do not reach the baby. In this study we use a Dsg1-specific ELISA to test anti-Dsg1 autoantibodies of the IgM, IgG and the IgG subclasses in the sera of 68 pairs of normal mothers and their neonates living in a highly endemic area of FS. Determination of these baseline anti-Dsg1 autoantibodies will allow us to follow and predict in this and other cohorts the appearance of preclinical serological markers of FS. METHODS: The sera of mothers and neonates living in the endemic region were tested by ELISA for IgM, IgG and IgG subclasses using recombinant Dsg1 and anti-IgG subclass-specific monoclonal antibodies. RESULTS: The index values of anti-Dsg1 IgG1, IgG2 and IgG3 are similar in mothers and neonates (all p>0.18), while the index values of IgM, total IgG and IgG4 are higher in mothers (all p<0.001). CONCLUSIONS: Narrowing the IgM, IgG and IgG subclasses of mothers and neonates to autoantibodies against Dsg1, we found, as expected, that IgM remains only in maternal circulation. In three mothers and two neonates we detected IgG4 anti-Dsg1 autoantibodies above the normal range. The remaining IgG subclasses show low values. The results of the neonatal sera will serve as a baseline for ongoing seroepidemiological studies of children and adults in the endemic regions of FS.

Atopic dermatitis: correlation between non-damaged skin barrier function and disease activity.

BACKGROUND: Atopic dermatitis (AD) is a chronic dermatosis, predominant in childhood, characterized by pruritus and eczematous-type lesions with xerosis as the prominent clinical sign. OBJECTIVES: To analyze the correlation between biophysical measurements of skin barrier function and other assessment criteria of clinical severity according to Rajka and Langeland's criteria. METHODS: Biophysical measurements [transepidermal water loss (TEWL) and corneometry] were obtained from 120 patients with the diagnosis of AD. Serum levels of IgE were also evaluated. RESULTS: A significant correlation between corneometry, TEWL, and clinical severity of AD was found. Data showed an inverse correlation between corneometry, TEWL, and AD severity, and a significant difference (P < 0.001) between mean of corneometry and TEWL and AD severity (mild, moderate, and severe). As for IgE levels, corneometry had significant negative correlation, in contrast with TEWL, which showed a significant positive correlation (P < 0.001). CONCLUSION: Biophysical measurements of skin barrier in non-lesional skin of AD may work as an evaluation factor for AD severity.

IgG autoantibody response against keratinocyte cadherins in endemic pemphigus foliaceus (fogo selvagem).

It is well established that autoantibodies against desmoglein 3 and desmoglein 1 (Dsg1) are relevant in the pathogenesis of pemphigus vulgaris and pemphigus foliaceus, including its endemic form fogo selvagem (FS). Isolated reports have shown that in certain patients with these diseases, autoantibodies against other desmosomal cadherins and E-cadherin may also be present. The goal of this investigation was to determine whether FS patients and normal individuals living in endemic areas possess autoantibodies against other desmosomal cadherins and E-cadherin. By testing a large number of FS and endemic control sera by ELISA, we found a consistent and specific autoantibody response against Dsg1 and other keratinocyte cadherins in these individuals, which is quite different from healthy individuals from the United States (US controls). Overall, the highest correlations among the autoantibody responses tested were in the endemic controls, followed by FS patients, and lowest in the US controls. These findings suggest that multiple, perhaps cross-reactive, keratinocyte cadherins are recognized by FS patients and endemic controls.

An insight into the sialotranscriptome of Triatoma matogrossensis, a kissing bug associated with fogo selvagem in South America.

Triatoma matogrossensis is a Hemiptera that belongs to the oliveirai complex, a vector of Chagas' disease that feeds on vertebrate blood in all life stages. Hematophagous insects' salivary glands (SGs) produce potent pharmacologic compounds that counteract host hemostasis, including anticlotting, antiplatelet, and vasodilatory molecules. Exposure to T. matogrossensis was also found to be a risk factor associated with the endemic form of the autoimmune skin disease pemphigus foliaceus, which is described in the same regions where Chagas' disease is observed in Brazil. To obtain a further insight into the salivary biochemical and pharmacologic diversity of this kissing bug and to identify possible allergens that might be associated with this autoimmune disease, a cDNA library from its SGs was randomly sequenced. We present the analysis of a set of 2,230 (SG) cDNA sequences, 1,182 of which coded for proteins of a putative secretory nature.

Profile of Trypanosoma cruzi reactivity in a population at high risk for endemic pemphigus foliaceus (Fogo selvagem).

Fogo selvagem (FS) is an autoimmune bullous disease with pathogenic IgG autoantibodies recognizing desmoglein 1 (Dsg1), a desmosomal glycoprotein. In certain settlements of Brazil, a high prevalence of FS (3%) is reported, suggesting environmental factors as triggers of the autoimmune response. Healthy individuals from endemic areas recognize nonpathogenic epitopes of Dsg1, and exposure to hematophagous insects is a risk factor for FS. Fogo selvagem and Chagas disease share some geographic sites, and anti-Dsg1 has been detected in Chagas patients. Indeterminate Chagas disease was identified in a Brazilian Amerindian population of high risk for FS. In counterpart, none of the FS patients living in the same geographic region showed reactivity against Trypanosoma cruzi. The profile of anti-Dsg1 antibodies showed positive results in 15 of 40 FS sera and in 33 of 150 sera from healthy individuals from endemic FS sites, and no cross-reactivity between Chagas disease and FS was observed.

Extensive long-standing chromomycosis due to Fonsecaea pedrosoi: three cases with relevant improvement under voriconazole therapy.

OBJECTIVE: To evaluate voriconazole in the treatment of extensive cases of chromomycosis. Chromomycosis is a chronic infection, which is extremely difficult to eradicate, and is caused by dematiaceous (dark-colored) fungi which affect the skin and subcutaneous tissues, with Fonsecaea pedrosoi being the major etiologic agent. Drugs such as itraconazole, terbinafine, posaconazole and amphotericin B have been employed with variable results. METHODS: We treated three Caucasian male patients (ages 44, 57 and 77 years), two were farmers and one a trash collector, with long-standing (20, 10 and 21 years of disease, respectively) and extensive chromomycosis (one lower limb affected, at least) due to Fonsecaea pedrosoi. All patients had received previous therapy with the formerly indicated drugs itraconazole and terbinafine for several months either without or with incomplete response. After that, we started treatment with voriconazole per os 200 mg twice a day. RESULTS: The patients were treated with voriconazole for 12 months until there was clinical and mycological improvement. Clinical response was evident after 30-50 days. One patient developed visual abnormalities and tremors, and the voriconazole was reduced to 200 mg/day without impairment of the clinical and mycological response. The same patient presented photosensitive dermatitis after 12 months of therapy and the voriconazole was stopped. All patients showed elevations of serum gamma-glutamyl transpeptidase (GGT) during the treatment without clinical relevance. Moreover, our three patients obtained partial response with this therapy. CONCLUSIONS: This is the first report with a case series of chromomycosis treated with voriconazole. Despite its high cost, voriconazole is a safe and possibly promising drug for use on extensive chromomycosis refractory to conventional treatment.