H. Turki

Anti-desmoglein 1 antibodies in Tunisian healthy subjects: arguments for the role of environmental factors in the occurrence of Tunisian pemphigus foliaceus

Pemphigus foliaceus is an autoimmune blistering skin disease mediated by autoantibodies directed against desmoglein 1 and occurs as a sporadic form throughout the world, or as an endemic form called fogo selvagem in Brazil. Healthy subjects living in Brazilian endemic areas produce antidesmoglein 1 antibodies, suggesting the role of environmental factors in the initiation of the autoimmune response. Tunisia was described recently as an endemic area where the disease is characterized by its high rate among young people, especially women. An enzyme‐linked immunosorbent assay using recombinant desmoglein 1 as antigen was used to detect antibodies against desmoglein 1 and calibrated with sera from 67 French healthy blood donors, 20 French pemphigus foliaceus patients and patients with other bullous skin diseases. When sera from 179 healthy Tunisian blood donors were tested, 31 (17%) were found positive. The desmoglein 1 binding activity of these 31 sera was confirmed in 10 cases by indirect immunofluorescence analysis and/or immunoblotting using human epidermal extract. Subclass analysis of antidesmoglein 1 antibodies showed that they were almost exclusively of the IgG2 subclass in positive normal sera and of IgG4 subclass in patients with PF. Thus, antibodies against desmoglein 1 are prevalent in normal subjects living in Tunisia which, along with their IgG2 isotype, suggests the role of the environment in the pathogenesis of this endemic type of pemphigus foliaceus and the need for additional factors to switch from a subclinical to a clinical form of the disease.

Tunisian endemic pemphigus foliaceus is associated with the HLA-DR3 gene: anti-desmoglein 1 antibody-positive healthy subjects bear protective alleles.

Background  Pemphigus foliaceus is an autoimmune blistering skin disease that partly results from genetic factors, especially human leucocyte antigen (HLA) class II genes.

Anti‐desmoglein 1 antibodies in healthy related and unrelated subjects and patients with pemphigus foliaceus in endemic and non‐endemic areas from Tunisia

Background  Pemphigus foliaceus is an autoimmune blistering skin disease characterized by the production of pathogenic IgG autoantibodies directed against desmoglein 1.

Tunisian endemic pemphigus foliaceus is associated with desmoglein 1 gene polymorphism.

Desmoglein 1 is the target antigen and probably the initiating immunogen of the autoantibody response in pemphigus foliaceus (PF), a blistering autoimmune skin disease. We previously showed that the desmoglein 1 gene (DSG1) is polymorphic and that one of its variants is associated with the sporadic form of PF observed in France. Herewith, we report, based on a case–control analysis, that the same DSG1 polymorphism participates in susceptibility to the endemic form of PF seen in Tunisia and, thus, show that common genetic factors govern the breakage of tolerance to desmoglein 1 in different epidemiological and environmental situations.

Anti-desmoglein-1 antibodies are prevalent in Tunisian patients with hydatidosis and leishmaniasis.

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Polymorphisms of HLA microsatellite marker in Tunisian pemphigus foliaceus.

Pemphigus foliaceus (PF) is an autoimmune blistering skin disease that partly results from genetic factors, especially from human leucocyte antigen (HLA) class II genes. Several data have reported the involvement of microsatellite (STR) markers across different regions of the HLA in many auto-immune diseases. To test the hypothesis of the existence of a major HLA haplotype predisposing to PF, we analyzed six polymorphisms of microsatellite loci at 6p21.3-21.4 spanning HLA: D6S291, D6S273, TNFa, MICA, D6S265 and D6S276 in 81 PF patients compared to 123 healthy individuals recruited from the south of Tunisia. In this study, after Bonferronis correction, 3 STR alleles from the TNFa locus were associated with the disease: the allele TNFa(∗)2 (p(c) = 4.2×10(-6)) and, at a lower level, the TNFa(∗)5 (p(c) = 0.014) as susceptibility alleles and TNFa(∗)6 (p(c) = 0.014) as protective ones. Furthermore, the expression of the TNFa(∗)2/TNFa(∗)5 genotype seem to confer susceptibility to PF (p = 0.00001, OR = 11.25). Interestingly, no significant LD was found between TNFa2/TNFa5 alleles and DRB1(∗)03/DRB1(∗)04 alleles. However, the multivariant regression analysis indicates that both the HLA class II and the TNFa alleles remained significant (p < 0.001). Although, these findings rejected our hypothesis on the existence of HLA susceptibility haplotype, they assessed the role of TNFa loci. Accordingly, TNFa seem to contribute to the aethiopathogenesis of Tunisian endemic PF may be by the induction of a high TNFα production which is known to enhance the autoimmune cascade of the disease.

The familial feature of Tunisian endemic pemphigus foliaceus

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Biomarkers of oxidative stress in epidermis of Tunisian pemphigus foliaceus patients

Background  Reactive oxygen species play a key role in the development of many dermatological disorders.

Pemphigus is not associated with allotypic markers of immunoglobulin kappa

The kappa light chain constant region of immunoglobulins bears polymorphic markers involved in susceptibility to various autoimmune diseases. To determine whether it also contributes to the occurrence of pemphigus, a group of autoimmune blistering skin diseases owing to pathogenic autoantibodies, the genotypic frequencies of Km allotypes were evaluated in patients with pemphigus foliaceus or pemphigus vulgaris and ethnically-matched healthy controls in both Tunisia and France. No difference in the distribution of Km genotype or allele frequencies was observed between patients and controls in either countries. Therefore, Km allotypes do not appear to constitute a genetic factor contributing to pemphigus.

Spectrum of autoantibodies other than anti-desmoglein in pemphigus patients

Background  Pemphigus is a life‐threatening autoimmune blistering disease mediated by autoantibodies against adhesion molecule of the skin. Its concurrence with systemic and organ‐specific autoimmune disease was described in case reports.