Genetic Associations and Differential mRNA Expression Levels of Host Genes Suggest a Viral Trigger for Endemic Pemphigus Foliaceus

The long search for the environmental trigger of the endemic pemphigus foliaceus (EPF, fogo selvagem) has not yet resulted in any tangible findings. Here, we searched for genetic associations and the differential expression of host genes involved in early viral infections and innate antiviral defense. Genetic variants could alter the structure, expression sites, or levels of the gene products, impacting their functions. By analyzing 3063 variants of 166 candidate genes in 227 EPF patients and 194 controls, we found 12 variants within 11 genes associated with differential susceptibility (p < 0.005) to EPF. The products of genes TRIM5, TPCN2, EIF4E, EIF4E3, NUP37, NUP50, NUP88, TPR, USP15, IRF8, and JAK1 are involved in different mechanisms of viral control, for example, the regulation of viral entry into the host cell or recognition of viral nucleic acids and proteins. Only two of nine variants were also associated in an independent German cohort of sporadic PF (75 patients, 150 controls), aligning with our hypothesis that antiviral host genes play a major role in EPF due to a specific virus−human interaction in the endemic region. Moreover, CCL5, P4HB, and APOBEC3G mRNA levels were increased (p < 0.001) in CD4+ T lymphocytes of EPF patients. Because there is limited or no evidence that these genes are involved in autoimmunity, their crucial role in antiviral responses and the associations that we observed support the hypothesis of a viral trigger for EPF, presumably a still unnoticed flavivirus. This work opens new frontiers in searching for the trigger of EPF, with the potential to advance translational research that aims for disease prevention and treatment.

Involvement of the Areae Compositae of the Heart in Endemic Pemphigus Foliaceus

Background

A new variant of endemic pemphigus foliaceus in El Bagre (El Bagre-EPF), Colombia, South America, shares features with Senear-Usher syndrome and occurs in an endemic fashion. Patients affected by El Bagre-EPF have heterogeneous antigenic reactivity not only to the skin but to other organs, including the heart. Here we test for autoantibodies to the areae compositae of the heart (structure consisting of typical desmosomal amalgamated fascia adherens molecules) and evaluate any possible clinical correlation.

Methods

A case-control study comparing 45 patients and 45 controls from the endemic area, matched by demographics including age, gender, weight, work activities, and comorbidities, was performed. Direct and indirect immunofluorescence, immunohistochemistry, confocal microscopic studies, and echocardiogram studies were completed.

Results

The main clinical abnormally seen in the El Bagre-EPF patients was left ventricular hypertrophy in 15/45 patients, compared with no such findings in the control population (P < 0.1). Seventy percent of El Bagre-EPF patients and none of the controls displayed polyclonal autoreactivity using different immunoglobulins and complement to the areae compositae of the heart using different methods and antibodies (P < 0.1).

Conclusions

Patients affected by El Bagre-EPF demonstrated autoantibodies to the areae compositae of the heart. This finding was associated with left ventricular hypertrophic cardiomyopathy. The areae compositae may play a role in cell junction tension and the El Bagre-EPF patients' autoantibodies possibly disrupting these junctions and thereby contributing to the left ventricular hypertrophy.

Subclinical oral involvement in patients with endemic pemphigus foliaceus

Background

We have described a variant of endemic pemphigus foliaceus (EPF) in El Bagre area known as pemphigus Abreu-Manu. Our previous study suggested that Colombian EPF seemed to react with various plakin family proteins, such as desmoplakins, envoplakin, periplakin BP230, MYZAP, ARVCF, p0071 as well as desmoglein 1.

Objectives

To explore whether patients affected by a new variant of endemic pemphigus foliaceus (El Bagre-EPF) demonstrated oral involvement.

Materials and Methods

A case-control study was done by searching for oral changes in 45 patients affected by El Bagre-EPF, as well as 45 epidemiologically matched controls from the endemic area matched by demographics, oral hygiene habits, comorbidities, smoking habits, place of residence, age, sex, and work activity. Oral biopsies were taken and evaluated via hematoxylin and eosin staining, direct immunofluorescence, indirect immunofluorescence, confocal microscopy, and immunohistochemistry.

Results

Radicular pieces and loss of teeth were seen in in 43 of the 45 El Bagre-EPF patients and 20 of the 45 controls (P < 0.001) (confidence interval [CI] 98%). Hematoxylin and eosin staining showed 23 of 45 El Bagre-EPF patients had corneal/subcorneal blistering and lymphohistiocytic infiltrates under the basement membrane zone and around the salivary glands, the periodontal ligament, and the neurovascular bundles in all cell junction structures in the oral cavity; these findings were not seen in the controls (P < 0.001) (CI 98%). The direct immunofluorescence, indirect immunofluorescence, confocal microscopy, and microarray staining displayed autoantibodies to the salivary glands, including their serous acini and the excretory duct cell junctions, the periodontal ligament, the neurovascular bundles and their cell junctions, striated muscle and their cell junctions, neuroreceptors, and connective tissue cell junctions. The autoantibodies were polyclonal. IgA autoantibodies were found in neuroreceptors in the glands and were positive in 41 of 45 patients and 3 of 45 controls.

Conclusions

Patients affected by El Bagre-EPF have some oral anomalies and an immune response, primarily to cell junctions. The intrinsic oral mucosal immune system, including IgA and secretory IgA, play an important role in this autoimmunity. Our data contradict the hypothesis that pemphigus foliaceus does not affect the oral mucosa due to the desmoglein 1-desmoglein 3 compensation.

Cell junction protein armadillo repeat gene deleted in velo-cardio-facial syndrome is expressed in the skin and colocalizes with autoantibodies of patients affected by a new variant of endemic pemphigus foliaceus in Colombia

Background

We previously described a new variant of endemic pemphigus foliaceus in El Bagre, Colombia, South America (El Bagre-EPF, or pemphigus Abreu-Manu). El Bagre-EPF differs from other types of EPF clinically, epidemiologically, immunologically and in its target antigens. We reported the presence of patient autoantibodies colocalizing with armadillo repeat gene deleted in velo-cardio-facial syndrome (ARVCF), a catenin cell junction protein colocalizing with El Bagre-EPF autoantibodies in the heart and within pilosebaceous units along their neurovascular supply routes. Here we investigate the presence of ARVCF in skin and its possibility as a cutaneous El Bagre-EPF antigen.

Methods

We used a case-control study, testing sera of 45 patients and 45 controls via direct and indirect immunofluorescence (DIF/IIF), confocal microscopy, immunoelectron microscopy and immunoblotting for the presence of ARVCF and its relationship with El Bagre-EPF autoantibodies in the skin. We also immunoadsorbed samples with desmoglein 1 (Dsg1) ectodomain (El Bagre-EPF antigen) by incubating with the positive ARVCF samples from DIF and IIF.

Results

ARVCF was expressed in all the samples from the cases and controls. Immunoadsorption with Dsg1 on positive ARVCF immunofluorescence DIF/IIF cases showed that the immune response was present against non-desmoglein 1 antigen(s). Overall, 40/45 patients showed colocalization of their autoantibodies with ARVCF in the epidermis; no controls from the endemic area displayed colocalization.

Conclusions

We demonstrate that ARVCF is expressed in many areas of human skin, and colocalizes with the majority of El Bagre-EPF autoantibodies as a putative antigen.

Cardiac autoantibodies from patients affected by a new variant of endemic pemphigus foliaceus in Colombia, South America

Several patients affected by a new variant of endemic pemphigus foliaceus in El Bagre, Colombia (El Bagre-EPF) have experienced a sudden death syndrome, including persons below the age of 50. El Bagre-EPF patients share several autoantigens with paraneoplastic pemphigus patients, such as reactivity to plakins. Further, paraneoplastic pemphigus patients have autoantibodies to the heart. Therefore, we tested 15 El Bagre-EPF patients and 15 controls from the endemic area for autoreactivity to heart tissue using direct and indirect immunofluorescence, confocal microscopy, immunohistochemistry, immunoblotting, and immunoelectron microscopy utilizing heart extracts as antigens. We found that 7 of 15 El Bagre patients exhibited a polyclonal immune response to several cell junctions of the heart, often colocalizing with known markers. These colocalizing markers included those for the area composita of the heart, such as anti-desmoplakins I and II; markers for gap junctions, such as connexin 43; markers for tight junctions, such as ezrin and junctional adhesion molecule A; and adherens junctions, such pan-cadherin. We also detected colocalization of the patient antibodies within blood vessels, Purkinje fibers, and cardiac sarcomeres. We conclude that El Bagre-EPF patients display autoreactivity to multiple cardiac epitopes, that this disease may resemble what is found in patients with rheumatic carditis, and further, that the cardiac pathophysiology of this disorder warrants further evaluation.

Endemic pemphigus over a century: Part II

BACKGROUND

Endemic pemphigus foliaceus (EPF) is an autoimmune disease, classically occurring in a restricted geographic area. Foci of EPF have been described in several Central and South American countries, often affecting young people and Amerindians, with some female predilection. Although most American EPF cases have been documented in Brazil, cases have been reported in Peru, Paraguay, El Salvador and Venezuela. An additional variant of EPF has been described in El Bagre, Colombia, (El Bagre-EPF) affecting older men and a few post-menopausal females. Finally, one additional type of EPF has been described in nomadic tribes affecting females of child bearing age in Tunisia, Africa.

AIMS

The main aim of this review is to summarize current knowledge about autoantigens, and immunologic and genetic studies in EPF.

MATERIAL AND METHODS

We utilized a retrospective review of the literature, aiming to compile and compare the multiple geographic foci of EPF.

RESULTS

The primary autoantigens in EPF are still considered to be desmogleins in the case of the Tunisian and all American cases, in contradistinction to plakins and desmogleins in El Bagre-EPF. Although several autoantigens are been suggested, their biochemical nature needs further elucidation. Current knowledge still supports the concept that an antibody mediated immune response represents the principal pathophysiology in all variants of EPF.

CONCLUSION

A strong genetic susceptibility appears to contribute to disease development in several people affected by these diseases; however, no specific genes have been confirmed at present. We conclude that further investigation is necessary to define these disorders immunologically and genetically.

Endemic pemphigus foliaceus over a century: Part I

BACKGROUND

Endemic pemphigus foliaceus (EPF) is the only known autoimmune disease presenting in circumscribed geographic areas.

AIM

We aim to provide information concerning the natural course of EPF, including systemic compromise in the presteroid era, which has been largely unavailable in the current medical literature. MATERIAL #ENTITYSTARTX00026;

METHODS

By a retrospective review of the literature we aim to compile and compare the focus of EPF and the current knowledge about them. The main aim of this review is to summarize our current knowledge of EPF, including data described almost one century ago; and, to include several unindexed reports, which may have not been available to many current scientists and health care personnel.

RESULTS

Foci of EPF have been described in several Central American and South American countries, affecting predominately young people and Amerindians, with an additional female predilection. Although most cases have occurred in Brazil, some cases have been reported in Peru, Paraguay, El Salvador, and Venezuela. Another variant of EPF has been described in El Bagre, Colombia, affecting older men and a few post-menopausal females. Finally, another type of EPF was described in nomadic tribes affecting females of child bearing age in Tunisia, Africa.

CONCLUSION

Our understanding of EPF has been hampered by a lack of government attention to these diseases, especially in some South and Central American countries. Other factors that have made past studies of EPF difficult include 1) that the disease foci are often located in rural areas bordering the rain forest of underdeveloped countries; and 2) military conflicts in some of these areas.