Background Systemic lupus erythematosus (SLE) is an autoimmune chronic inflammatory disease that presents a variety of clinical manifestationsand immunological abnormalities.There is evidence that immunological, environmental, hormonal and genetic factors may contribute to the occurrence of the disease. Genes and proteins involved in metabolism/detoxification of xenobiotics are often used as markers of susceptibility to the development of diseases whose etiology is related to exposure to environmental risk factors. Cytochrome P450 (CYP) enzymes are primarily responsible for phase I detoxification, in which activate the xenobiotic, making it more electrophilic and thus more reactive. The Glutathione S-transferases (GST) are phase II detoxifying enzymesand usually conjugate reduced glutathione with a variety of electrophilic compounds, such as reactive oxygen species, facilitating the excretion of toxic products. Polymorphismsin the CYP and GST genes can alter the expression and catalytic activity of enzymes, being responsible for interindividual differences regarding the capacity of xenobiotics biotransformation.
Objectives To evaluate the influence of three GST polymorphisms (GSTM1 null, GSTT1 null and GSTP1*Val) and two CYP polymorphisms (CYP1A1*2C and CYP2E1*5B) in SLE predisposition.
Methods This study included 370 SLE patients who were followed at the Division of Rheumatology of Hospital de Clínicas de Porto Alegre, and 329 healthy blood donors, both groups from Southern Brazil. The CYP polymorphisms were genotyped by PCR-RFLP, while the GST polymorphisms were genotyped by multiplex PCR and PCR-RFLP for GSTP1.
Results Analyses were performed subdividing the individuals according to their ethnic origin. Among European-derived individuals, it was observed a lower frequency of GSTP1*Val heterozygous genotypes in SLE patients compared to controls (36% vs. 48%, p=0.0047; OR 0.63 CI 95% 0.43 - 0.93 in relation to GSTP1*Ile/Ile and OR 0.49 95% CI 0.26 - 0.92 in relation to GSTP1*Val/Val). In African-derived group, the CYP2E1*5B allele was significantly more frequent in patients than in matched controls (11% vs. 5%, p=0.038, OR 2.69 95% CI 1.00 - 8.42). We did not observe any association of the CYP and GST polymorphisms with the SLE clinical manifestations.
Conclusions Our data suggest a protective role of the GSTP1*105Ile/Val heterozygous genotype in European-derived and a possible influence of the CYP2E1*5B allele in SLE susceptibility among African-derived. These findings may indicate new mechanisms of interaction among environment, genetics and the triggering of SLE.
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Disclosure of Interest None Declared