Evaluation of IFIT3 and ORM1 as Biomarkers for Discriminating Active Tuberculosis from Latent Infection.

OBJECTIVE: Current commercially available immunological tests cannot be used for discriminating active tuberculosis (TB) from latent TB infection. To evaluate the value of biomarker candidates in the diagnosis of active TB, this study aimed to identify differentially expressed genes in peripheral blood mononuclear cells (PBMCs) between patients with active TB and individuals with latent TB infection by transcriptome sequencing. METHODS: The differentially expressed genes in unstimulated PBMCs and in Mycobacterium tuberculosis (Mtb) antigen-stimulated PBMCs from patients with active TB and individuals with latent TB infection were identified by transcriptome sequencing. Selected candidate genes were evaluated in cohorts consisting of 110 patients with TB, 30 individuals with latent TB infections, and 50 healthy controls by quantitative real-time RT-PCR. Receiver operating characteristic (ROC) curve analysis was performed to calculate the diagnostic value of the biomarker candidates. RESULTS: Among the differentially expressed genes in PBMCs without Mtb antigen stimulation, interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) had the highest area under curve (AUC) value (0.918, 95% CI: 0.852-0.984, P<0.0001) in discriminating patients with active TB from individuals with latent TB infection, with a sensitivity of 91.86% and a specificity of 84.00%. In Mtb antigen-stimulated PBMCs, orosomucoid 1 (ORM1) had a high AUC value (0.833, 95% CI: 0.752-0.915, P<0.0001), with a sensitivity of 81.94% and a specificity of 70.00%. CONCLUSION: IFIT3 and ORM1 might be potential biomarkers for discriminating active TB from latent TB infection.

Mesenchymal-epithelial Transition Factor Regulates Monocyte Function during Mycobacterial Infection via Indoleamine 2,3-dioxygenase.

OBJECTIVE: Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), causes an estimated 1.6 million human deaths annually, but the pathogenesis of TB remains unclear. Immunity plays a critical role in the onset and outcome of TB. This study aimed to uncover the roles of innate and adaptive immunity in TB. METHODS: The gene expression profiles generated by RNA sequencing from human peripheral blood mononuclear cells (PBMCs) stimulated with or without Mtb strain H37Rv antigens were analyzed. A total of 973 differentially expressed mRNAs were identified. RESULTS: The differentially expressed genes were enriched in innate immunity signaling functions. The mesenchymal-epithelial transition factor (MET) gene was significantly upregulated in CD14+ monocytes. A MET inhibitor improved the uptake of the BCG strain by monocytes and macrophages as well as inhibited the expression of indoleamine 2,3-dioxygenase (IDO). The expression of IDO was increased in PBMCs stimulated with Mtb antigens, and the IDO inhibitor promoted the expression of CD40, CD83, and CD86. CONCLUSION: Our results might provide clues regarding the immunomodulatory mechanisms used by Mtb to evade the host defense system.