Interleukin-1 gene cluster polymorphism in chagas disease in a Colombian case-control study

The aim of this study was to assess the possible association between the IL1A, IL1B and IL1RN gene polymorphisms and Chagas disease. Our study population consisted of 130 serologically positive cardiomyopathic patients and 130 seropositive and asymptomatic individuals from a Colombian population where Trypanosoma cruzi infection is endemic. Genotyping of the IL1A (-889C/T, +4845G/T), IL1B (-511C/T, -31T/C, +3954T/C, +5810G/A) and IL1RN (+8006T/C, +8061C/T, +11100T/C) polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction sequence-specific primer methods. Statistically significant differences in the distribution of the IL1B +5810 genotypes were observed comparing cardiomyopathic patients and asymptomatic individuals (p = 0.036). Frequency of the GG genotype was higher in the cardiomyopathic patient group than in the asymptomatic group (13% versus 5%, p = 0.03, odds ratio [OR] = 2.64, 95% confidence interval [CI] = 0.99-7.33). Differences in the distribution of the allele frequencies were also observed, being the +5810G allele overrepresented in patients with cardiomyopathy (37% versus 27%, p = 0.014, OR = 1.59, 95% CI = 1.08-2.36). Examination of markers in the IL1A (-889 and +4845), IL1B (-511, -31, and +3954) and IL1RN (+11100) genes revealed that the overall distribution of alleles and genotypes in patients with chagasic cardiomyopathy and asymptomatic were not significantly different. Our results show that in Colombian population the IL1B+5810G allele was associated with an increased risk chagasic cardiomyopathy. In addition, we demonstrated that homozygosity for the IL1B +5810G risk allele increased significantly the susceptibility to cardiomyopathy. This implies that the effect of IL1B gene on chagasic cardiomyopathy predisposition is dose dependent. We found that the haplotype CT of IL1B -31 and +3954 polymorphisms showed higher association with risk to chagasic cardiomyopathy (p(c) = 0.008, OR = 12.53) and the extended haplotype (CCTCATT) was significantly more frequent in asymptomatic than in cardiomyopathic patients (p = 0.0014, p(c) = 0.011, OR = 0.17). Therefore this study suggests that IL1 gene cluster polymorphisms may play a relevant role in the susceptibility to development of chagasic chronic cardiomyopathy.