CD59 polymorphisms are associated with gene expression and different sexual susceptibility to pemphigus foliaceus.

Pemphigus foliaceus (PF) is an autoimmune disease, endemic in Brazilian rural areas, characterized by acantholysis and accompanied by complement activation, with generalized or localized distribution of painful epidermal blisters. CD59 is an essential complement regulator, inhibiting formation of the membrane attack complex, and mediating signal transduction and activation of T lymphocytes. CD59 has different transcripts by alternative splicing, of which only two are widely expressed, suggesting the presence of regulatory sites in their noncoding regions. To date, there is no association study with polymorphisms in CD59 noncoding regions and susceptibility to autoimmune diseases. In this study, we aimed to evaluate if CD59 polymorphisms have a possible regulatory effect on gene expression and susceptibility to PF. Six noncoding polymorphisms were haplotyped in 157 patients and 215 controls by sequence-specific PCR, and CD59 mRNA levels were measured in 82 subjects, by qPCR. The rs861256-allele-G (rs861256*G) was associated with increased mRNA expression (p = .0113) and PF susceptibility in women (OR = 4.11, p = .0001), which were also more prone to develop generalized lesions (OR = 4.3, p = .009) and to resist disease remission (OR = 3.69, p = .045). Associations were also observed for rs831625*G (OR = 3.1, p = .007) and rs704697*A (OR = 3.4, p = .006) in Euro-Brazilian women, and for rs704701*C (OR = 2.33, p = .037) in Afro-Brazilians. These alleles constitute the GGCCAA haplotype, which also increases PF susceptibility (OR = 4.9, p = .045) and marks higher mRNA expression (p = .0025). In conclusion, higher CD59 transcriptional levels may be related with PF susceptibility (especially in women), probably due to the effect of genetic polymorphism and to the CD59 role in T cell signal transduction.

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.

HLA-DRB1*0402 haplotypes without DQB1*0302 in Venezuelan patients with pemphigus vulgaris.

The two basic forms of autoimmune intraepidermal blistering diseases, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), affect different layers of the skin, have different symptoms and target different antigens. We have defined human leukocyte antigen (HLA)-DRB1-DQB1 alleles and haplotypes in a case-control study of 66 non-Jewish patients attending a public reference Hospital over the past 10 years. The control group consisted of 101 matched individuals tested also by medium to high-resolution polymerase chain reaction-sequence-specific oligonucleotide with primers and probes from the 12th and 13th International Histocompatibility Workshop. Patients and controls were descendants of three-generation individuals born in the country. Among the patients, 49 had PV, 50% showed predominantly mucosal involvement, 50% showed predominantly the cutaneous clinical phenotype and 17 had PF. Statistically significant HLA-DR frequency differences between patients with PV and controls were found only for DRB1*0402 and DRB1*1401 [odds ratio (OR) = 27.22, confidence interval (CI) 94.7-7.82, P= 1.1 x 10(-14) and OR = 46.56, CI 801.4-2.70 P= 7.5 x 10(-6), respectively]. Both alleles were also increased in the patients with PF compared with the controls (OR = 7.0, P= 0.038 and OR = 21.64, P= 0.009, respectively), but the significance of the difference did not resist Bonferroni correction. Haplotype analysis showed that DRB1*0402 was always present with DQB1*0302 and DRB1*1401 with DQB1*0503, but no independent effect of the DQB1*0302 in the former haplotype was evident. Our results support the hypothesis that the DRB1*0402 without DQB1*0302 is the most relevant HLA-DRB1 allele responsible for the pathogenesis of pemphigus in Venezuelan patients with PV and discard the DQB1*0302 influence observed in other populations.

Environmental risk factors in endemic pemphigus foliaceus (fogo selvagem).

An ongoing sero-epidemiological study of the Terena reservation of Limao Verde, known to have a high prevalence and incidence of FS, has revealed important information about this autoimmune disease. During surveillance of this population of approximately 1,200, which began in 1994, we documented 43 FS cases and studied the transition from the normal state to the disease state in several of these individuals. Furthermore, we established that FS patients as well as a large number of normal individuals on the reservation possess anti-dsg1 autoantibodies. The following interesting observations were made: (1) the ectodomain of dsg1 contains epitopes recognized by both autoantibodies and T cells from FS patients; (2) pathogenic anti-dsg1 autoantibodies in FS belong to the IgG4 subclass; (3) nonpathogenic anti-dsg1 autoantibodies of the IgG1 subclass were detected in normal individuals from Limao Verde and in patients in the preclinical stage of the disease; (4) anti-dsg1 autoantibodies from normal individuals and patients in the preclinical stage of FS recognize the EC5 domain of dsg1, whereas pathogenic anti-dsg1 autoantibodies bind the EC1/EC2 domains; (5) houses of FS patients are rustic, with thatched roofs and walls and dirt floors; (6) there was a high frequency of hematophagous insects (bedbugs and kissing bugs) in the houses of FS patients; (7) previous studies revealed that the predominant black fly on this reservation belongs to the species Simunlium nigrimanum. These findings suggest that the environmental antigen(s) triggering the autoimmune response in FS may be linked to exposure to hematophagous insects.

Endemic pemphigus foliaceus (fogo selvagem) in native Americans from Brazil.

BACKGROUND: Fogo selvagem (FS) is an autoimmune disease that is endemic in certain regions of Brazil and appears to be precipitated by an environmental factor. OBJECTIVE: Our purpose was to confirm the occurrence and prevalence of FS in a population of Xavante Indians living in an endemic region of central Brazil. METHODS: Clinical, anthropologic, and immunologic studies were carried out in patients and in normal inhabitants of the Pimentel Barbosa Indian Reservation, Mato Grosso, Brazil. RESULTS: FS was identified and confirmed in 10 patients from a patient pool of 295 with various skin diseases. The Xavante settlement has a total population of 746. Anti-desmoglein 1 autoantibodies were detected in all patients with FS and were absent from more than 300 serum samples collected from randomly selected unaffected persons. CONCLUSION: FS is strongly linked to outdoor activities and is largely restricted to immunogenetically predisposed persons. FS appears to have been endemic in certain regions of South America for several centuries.