Background. Unlike tuberculosis, few studies have evaluated a host genetic basis for variability in susceptibility to latent Mycobacterium tuberculosis infection (LTBI). We performed a candidate gene association study of autophagy-related genes and LTBI.
Methods. We enrolled close contacts of individuals with pulmonary tuberculosis, assessed LTBI status, and determined clinical and sociodemographic risk factors for LTBI. In participants who self-identified as Asian or black, we compared haplotype-tagging single-nucleotide polymorphisms (SNPs) in ULK1 and GABARAP between cases (n = 143) and controls (n = 106). Using CRISPR/Cas9 in U937 monocytes, we investigated the effect of ULK1 deficiency on cytokine expression, autophagy, and M. tuberculosis replication.
Results. In Asian participants, we identified 2 ULK1 SNPs (rs12297124 and rs7300908) associated with LTBI. After adjustment for population admixture and clinical risk for LTBI, each rs12297124 minor allele conferred 80% reduction in LTBI risk (odds ratio, 0.18; 95% confidence interval, .07–.46). Compared with controls, ULK1-deficient cells exhibited decreased tumor necrosis factor secretion after stimulation with Toll-like receptor ligands and M. tuberculosis whole-cell lysate, increased M. tuberculosis replication, and decreased selective autophagy.
Conclusions. These results demonstrate a strong association of rs12297124, a noncoding ULK1 SNP, with LTBI and a role for ULK1 regulation of TNF secretion, nonspecific and M. tuberculosis–induced autophagy, and M. tuberculosis replication in monocytes.