ROLE OF THE AUTOIMMUNE REGULATOR (AIRE) GENE IN SYSTEMIC SCLEROSIS ASSOCIATED WITH OTHER AUTOIMMUNE DISEASES

Background: The autoimmune regulator (AIRE) gene has been shown to be involved in the genesis of autoimmunity in subjects affected by the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), and more recently in the pathogenesis of alopecia. Considering that SSc, object of the present study, has a deep cutaneous involvement, and is frequently associated with other autoimmune diseases, we hypothesize that mutations and/or polymorphisms in the AIRE gene might be involved in the complex pathogenesis of the disease, when associated with other autoimmune failures common to APECED. Objectives: The proposed study aims to evaluate mutations/polymorphisms of AIRE gene in patients affected by Systemic Sclerosis (SSc) associated with other autoimmune diseases such as autoimmune thyroiditis and/or vitiligo. Methods: Patients and controls: A case-control study was performed in 20 patients affected by Ssc and autoimmune thyroiditis, and 40 healthy control subjects. Genetic Analysis: Genomic DNA of all the 20 patients was extracted from 300 ul of peripheral blood. Primers were designed within the introns flanking each of the 14 exons of the AIRE sequence (GeneBank accession number: AB006684).PCR products were then purified from agarose gel and automatically sequenced using ABI 377 machine (Applied Biosystems, Foster City, CA). To evaluate genotype distribution of AIRE polymorphisms, a PCR-RFLP was performed on genomic DNA from healthy controls.Allelic discrimination was performed by 2% agarose electrophoresis. Statistical Analysis. Disease and control population were compared using 2X2 chi-square test. Results: Twenty patients affected by SSc and autoimmune thyroiditis have been analyzed against 40 healthy controls. Among patients DNA, they have been identified 10 variants of the AIRE gene: 9 polimorfisms, of which one lead to an amino acid change S278R, and 1 mutation V301M. S278R has been shown to be associated with alopecia aereata, while V301M has been observed once in a female with Addison''s desease, autoimmune thyroiditis, and gonad failure. S278R belongs to the SAND domain of the protein, which is responsible for DNA binding, V301M is in the PH1 domain responsible for protein to protein interaction. Conclusion: Data collected so far do not show a significant correlation of those two variants with the pathogenesis SSc associated with others autoimmune deseases. On the other side in none of the healthy controls V301M has been found. This data suggests that the implementation of number of SSc cases could lead to a significative result. Finding genetic variants statistically significant in the AIRE gene, could lead to better understand the genesis of broad autoimmune manifestations in a selected group of SSc affected patients. Influence of AIRE gene in SSc will be add precious information on the development of organ specific autoimmune diseases during the evolvement of the disease.