Association of interleukin-1β and interleukin-1 receptor antagonist polymorphisms with bacterial vaginosis in non-pregnant Italian women

Bacterial vaginosis (BV) is the most prevalent alteration of vaginal microflora worldwide. BV is a polymicrobial disorder, and its etiology is elusive. Factors predisposing to this recurrent condition are not fully characterized. We aimed to investigate whether interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1ra) polymorphisms are associated with BV in non-pregnant white Italian women. Genomic DNA was obtained from 164 BV positive, and 406 control women. Two diallelic polymorphisms in the IL-1 beta gene (IL-1B) representing C/T base transitions at -511 and +3954 positions and a variable number tandem repeats (VNTR) in intron 2 of the IL-1ra gene (IL-1RN) were assessed. We demonstrated that women who were homozygous for -511 CC or +3954 TT of the IL-1B gene were at increased risk for BV with an odds ratio (OR) = 1.5 [95% confidence interval (CI) = 1.03-2.14, P = 0.032], and OR = 2.8 (95% CI = 1.37-5.88, P = 0.004), respectively. The haplotype -511/+3954 T-C was protective for BV, with an OR = 0.7 (95% CI = 0.49-0.90, P = 0.009). The IL-1RN VNTR genotype was not associated with BV, although the rare allele 3 showed a trend towards protection (P = 0.049). These data show that host genetic variants at the IL-1 beta locus predispose to BV among Caucasian non-pregnant women. Further studies will determine whether these genetic polymorphisms modulate the risk for BV recurrence, and/or BV associated severe adverse outcomes as preterm birth and human immunodeficiency virus transmission.