Mycobacterium tuberculosis-derived circulating cell-free DNA in patients with pulmonary tuberculosis and persons with latent tuberculosis infection.

OBJECTIVES: The timely diagnosis of pulmonary tuberculosis (PTB) is challenging. Although pathogen-derived circulating cell-free DNA (cfDNA) has been detected in humans, the significance of Mycobacterium tuberculosis (MTB)-cfDNA detection in patients with PTB remains unclear. METHODS: This study enrolled patients with PTB and persons with latent tuberculosis infection (LTBI) as the study and control groups, respectively, from 2018 to 2020. We measured interferon-γ levels and calculated blood monocyte-to-lymphocyte ratio (MLR). We conducted plasma cfDNA extraction, quantitative polymerase chain reaction (qPCR), and droplet digital PCR targeting the IS6110 gene of MTB. We calculated the sensitivity and specificity of using MTB-cfDNA to identify PTB and analyzed the factors associated with PTB diagnosis and MTB-cfDNA positivity. RESULTS: We enrolled 24 patients with PTB and 57 LTBI controls. The sensitivity of using MTB-cfDNA to identify PTB was 54.2%(13/24) in total and 46.2%(6/13) in smear-negative cases. Two LTBI controls (3.5%) tested positive for MTB-cfDNA, indicating a specificity of 96.5%(55/57). By using MTB-cfDNA positivity and an MLR ≥0.42 to identify PTB, sensitivity increased to 79.2%(19/24). Among patients with PTB, MTB-specific interferon-γ levels were higher in MTB-cfDNA positive participants than in those who tested negative (7.0 ±2.7 vs 2.7±3.0 IU/mL, p<0.001). MTB-cfDNA levels declined after 2 months of anti-tuberculosis therapy (p<0.001). CONCLUSION: The sensitivity of using MTB-cfDNA to identify PTB in participants was 54.2%, which increased to 79.2% after incorporating an MLR ≥0.42 into the analysis. MTB-cfDNA positivity was associated with MTB-specific immune response, and MTB-cfDNA levels declined after treatment. The clinical value of MTB-cfDNA in PTB management necessitates further investigation.

TREM-1 enhances Mycobacterium tuberculosis-induced inflammatory responses in macrophages.

Triggering receptor expressed on myeloid cells 1 (TREM-1) extensively interacts with toll-like receptors and amplifies pro-inflammatory responses. The effect of TREM-1 on Mycobacterium tuberculosis (MTB)-related immune responses remains to be elucidated. We isolated bone marrow-derived macrophages (BMDMs) from wild-type mice and Trem-1 KO mice and treated them with MTB whole cell lysate and EsxA (ESAT-6). Cytokine production and mRNA expression, including Trem-1, following stimulation were evaluated. Intratracheal instillation of heat-killed MTB (HKMTB) in mice was performed and the presence of TREM-1-positive macrophages was investigated by immunohistochemistry analysis. In our study, BMDMs isolated from wild-type mice produced more pro-inflammatory cytokines and demonstrated higher inflammatory gene expression levels compared with those isolated from Trem-1 KO mice when stimulated with MTB whole cell lysate. EsxA had a synergistic effect with MTB whole cell lysate on the induction of pro-inflammatory responses. The gene expression of Trem-1 was upregulated when treated with MTB-related proteins. TREM-1-positive macrophages were identified in the lung tissues from patients with active TB and from wild-type mice treated with intratracheal instillation of HKMTB. In conclusion, in mouse macrophages, TREM-1 could enhance pro-inflammatory immune responses when stimulated with MTB-related proteins. The gene expression of Trem-1 could also be induced by MTB-related stimulation.

Depression and recovery of IL-17A secretion in mitogen responses in patients with active tuberculosis-a prospective observational study.

BACKGROUND/PURPOSE: T-helper cell 17 (Th17) is a distinct subset of CD4+ T lymphocytes that is important in the pathogenesis of Mycobacterium tuberculosis infection. This study aims to investigate the characteristics of interleukin (IL)-17A and Th17-related cytokines after stimulation with phytohemagglutinin in patients with active tuberculosis (TB). METHODS: This prospective cohort study enrolled patients with culture-confirmed active TB. QuantiFERON-TB Gold In-Tube (QFT-GIT) assay was performed upon TB diagnosis and at 2 months after TB treatment. Their non-TB-specific secretion of IL-17A and Th17-related cytokines were measured in supernatants of mitogen tubes in QFT-GIT and compared to those of active TB contacts with or without latent TB infection. We analyzed the association between IL-17A secretions and TB presentation and treatment outcomes. RESULTS: A total of 108 patients with TB and 64 non-TB cases were enrolled. The secretion of IL-17A, IL-21, IL-23, and IL-6 were lower in active TB patients upon TB diagnosis. In active TB patients, lower IL-17A secretions were associated with higher grades of sputum smear. In the multivariate analysis, lower IL-17A secretions served as an independent factor associated with 2-month culture non-conversion (odds ratio 23.04, 95% confidence interval [CI] 1.69-84.78) and on-treatment mortality (hazard ratio 28.54, 95% CI 1.30-99.25). The levels of IL-23, and IL-6 significantly increased after 2 months of anti-TB treatment. CONCLUSION: The non-TB-specific IL-17A secretions were lower in active TB patients upon TB diagnosis and associated with higher disease severity and worse treatment outcomes. Trend of recovery of the depressed Th17-related cytokines was noted after effective anti-TB treatment.

Metformin use and post-exposure incident tuberculosis: a nationwide tuberculosis-contact cohort study in Taiwan.

This TB contact cohort study showed that the risk of incident TB, not coprevalent TB, was highest in the diabetes group without metformin use during TB exposure, followed by the nondiabetes population, and was lowest in the diabetes group with metformin use https://bit.ly/3fpJyF0.