LMP2/LMP7 gene variant: a risk factor for intestinal Mycobacterium tuberculosis infection in the Chinese population

Low molecular mass protein-2 (LMP2) and low molecular mass protein-7 (LMP7) genes play a critical role in foreign antigen processing on the major histocompatibility complex-I CD8(+) cytotoxic T-lymphocyte pathway. This study was designed to investigate whether the sequence variants in the LMP2/LMP7 coding region were associated with intestinal Mycobacterium tuberculosis (M. tuberculosis) infection or with the co-infection of pulmonary tuberculosis.

A total of 168 patients with intestinal tuberculosis and 235 normal controls were recruited for this study. Two polymorphisms of LMP2 (Arg60-His) and LMP7 (Gln145-Lys) were identified by polymerase chain reaction-restriction fragment length polymorphism method. The associations of the LMP2/LMP7 genotype and haplotype with intestinal M. tuberculosis infection were assessed by using logistic regression analysis.

The results revealed that LMP7 position codon 145 Lys/Lys and Gln/Lys alleles in the coding region were associated with the infection of intestinal M. tuberculosis (P=0.003, odds ratio [OR]= 3.86 and P < 0.001, OR = 2.28, respectively). Meanwhile, the Arg-Lys and Cys-Lys haplotypes exhibited significant relation to the intestinal M. tuberculosis infection (P= 0.006, OR=1.87; P=0.021, OR=1.83, respectively). No significant associations were observed for any of the single-nucleotide polymorphism genotypes or haplotypes with the co-infection of pulmonary tuberculosis (P > 0.05).

The results indicated that the genetic variant within the LMP2/LMP7 gene would increase the risk of intestinal M. tuberculosis infection.