The association between the genetic polymorphisms of LMP2/LMP7 and the outcomes of HCV infection among drug users.

Objective: To investigate a possible association of LMP2/LMP7 genes with chronic hepatitis C virus (HCV) infection, and to assess whether LMP2/LMP7 genes could influence the outcomes of HCV infection among drug users.

Methods: Genomic DNAs of 362 anti-HCV sero-positive drug users and 225 control drug users were extracted from the peripheral blood leukocytes. The sero-positive patients were divided into those who had persistent infection and those who had spontaneously cleared the infection. Polymorphisms of LMP genes were determined by PCR combined with restriction fragment length polymorphism (RFLP).

Results: The distribution of LMP2 genotypes among the control, persistent infection and spontaneous clearance groups were not different. However, the LMP7 codon 145 Gln/Lys, Lys/Lys, and Gln/Lys+Lys/Lys genotypes were found significantly more frequent in the persistent infection group than in control group (OR=1.75, 95%CI=1.06∼2.90; OR=3.16, 95%CI=1.23-8.12; OR = 1.94, 95%CI=1.21-3.12, respectively). Similarly, the frequencies of the codon 145 Gln/Lys, Lys/Lys, and Gln/Lys+Lys/Lys genotypes were found significantly more frequent in the persistent infection group than in the spontaneous clearance group (OR=1.64, 95%CI=1.04-2.57; OR=2.40, 95%CI=1.09-5.28; OR=1.76, 95%CI=1.15-2.69, respectively). Stratified analysis indicated that combined genotype Gln/Lys + Lys/Lys of the LMP7 gene was related to an increasing susceptibility to HCV infection (OR=1.91, 95%CI=1.02-3.55; OR=2.19, 95%CI=1.24-3.89; OR=1.91, 95%CI=1.05-3.48, OR=2.86, 95%CI=1.41-5.78, respectively) and the risk of persistent HCV infection (OR=1.94, 95%CI=1.12-3.34; OR=2.02, 95%CI=1.21-3.38; OR=1.78, 95%CI=1.12-2.85, OR=2.23, 95%CI=1.09-4.58, respectively) among > 30-year-old, males, the injection drug user (IDU) subjects and/or the shorter duration drug users (≤5 y).

Conclusion: These results suggest that polymorphism of the LMP7 gene may have an influence on the outcomes of HCV infection, and is one of the factors accounting for the genetic susceptibility to HCV infection among drug users.