Polymorphisms in ERAP1 and ERAP2 Genes Are Associated With Tuberculosis in the Han Chinese

Variation in ERAP2 has opposing effects on severe respiratory infection and autoimmune disease

ERAP2 is an aminopeptidase involved in immunological antigen presentation. Genotype data in human samples from before and after the Black Death, an epidemic due to Yersinia pestis, have marked changes in allele frequency of the single-nucleotide polymorphism (SNP) rs2549794, with the T allele suggested to be deleterious during this period, while ERAP2 is also implicated in autoimmune diseases. This study explored the association between variation at ERAP2 and (1) infection, (2) autoimmune disease, and (3) parental longevity. Genome-wide association studies (GWASs) of these outcomes were identified in contemporary cohorts (UK Biobank, FinnGen, and GenOMICC). Effect estimates were extracted for rs2549794 and rs2248374, a haplotype tagging SNP. Additionally, cis expression and protein quantitative trait loci (QTLs) for ERAP2 were used in Mendelian randomization (MR) analyses. Consistent with decreased survival in the Black Death, the T allele of rs2549794 showed evidence of association with respiratory infection (odds ratio; OR for pneumonia 1.03; 95% CI 1.01-1.05). Effect estimates were larger for more severe phenotypes (OR for critical care admission with pneumonia 1.08; 95% CI 1.02-1.14). In contrast, opposing effects were identified for Crohn disease (OR 0.86; 95% CI 0.82-0.90). This allele was shown to associate with decreased ERAP2 expression and protein levels, independent of haplotype. MR analyses suggest that ERAP2 expression may be mediating disease associations. Decreased ERAP2 expression is associated with severe respiratory infection with an opposing association with autoimmune diseases. These data support the hypothesis of balancing selection at this locus driven by autoimmune and infectious disease.

Transporter Associated with Antigen Processing 1 Gene Polymorphisms Increase the Susceptibility to Tuberculosis

Purpose

Tuberculosis (TB) is known to result from a complex interaction between the host immune response and Mycobacterium infection. The transporter associated with antigen processing (TAP) plays an important role in the processing and presentation pathways for the Mycobacterium tuberculosis (M. tb) antigen. To investigate the possible association of the TAP1 and TAP2 genes with TB.

Patients and Methods

A total of 449 TB patients and 435 control subjects were included in this study, and single nucleotide polymorphisms (SNPs) in the TAP gene, as well as TAP1 and TAP2 alleles, were genotyped.

Results

TAP gene association analysis of TB diseases showed that rs41551515-T in the TAP1 gene was significantly associated with susceptibility to TB (P=7.96E-04, OR=4.124, 95% CI: 1.683-10.102), especially pulmonary TB (PTB, P=6.84E-04, OR=4.350, 95% CI: 1.727-10.945), and the combination of rs1057141-T-rs1135216-C in the TAP1 gene significantly increased the risk of TB susceptibility (P=5.51E-05, OR=10.899, 95% CI: 2.555-46.493). Five novel TAP1 alleles were detected in Yunnan Han people, and the allele frequency of TAP1*unknown_3 (rs41555220-rs41549617-rs1057141-rs1135216-rs1057149-rs41551515: C-A-T-C-C-T) was notably increased in all TB patients, including in the PTB and EPTB subgroups, and was significantly associated with the risk of susceptibility to TB. However, no association between the TAP2 gene and TB was found in this study.

Conclusion

Host genetic variants of rs41551515-T and the combination rs1057141-T-rs1135216-C, as well as TAP1*unknown_3 may play a critical role in susceptibility to TB disease.