The persistent DNA methylation perturbations we have identified are a plausible explanation for why successful TB therapy must be continued for months after M. tuberculosis culture conversion. These data suggest that it is critical to evaluate whether modulating DNA methylation could effectively augment host antimycobacterial immunity.

Interferon-gamma release assays are increasingly used in children to establish evidence of tuberculosis (TB) infection and to assist in the diagnosis of TB disease. The QuantiFERON-TB Gold In-Tube assay is being phased out in favor of a next-generation test, the QuantiFERON-TB Gold Plus (QFT-Plus) assay. The QFT-Plus assay is designed with two antigen tubes to differentially stimulate CD4 + and CD8 + T cells. The performance of this assay has been documented extensively in adults but has not yet been evaluated in children. Here, we compare the performance of the two assays in a cohort of 46 children exposed to TB and 12 children diagnosed with TB disease in Eswatini. The tests demonstrated excellent concordance in both TB disease (100% agreement, Cohen's kappa = 1) and TB infection (96% agreement, Cohen's kappa = 0.91). Most of the children with household exposure tested negative for TB infection by both tests, indicating the ongoing need for new tests for TB infection that can be easily implemented in TB high-burden settings at minimal cost.

BackgroundIn vitro, animal model, and clinical evidence suggests that tuberculosis is not a monomorphic disease, and that host response to tuberculosis is protean with multiple distinct molecular pathways and pathologies (endotypes). We applied unbiased clustering to identify separate tuberculosis endotypes with classifiable gene expression patterns and clinical outcomes.MethodsA cohort comprised of microarray gene expression data from microbiologically confirmed tuberculosis patients were used to identify putative endotypes. One microarray cohort with longitudinal clinical outcomes was reserved for validation, as was two RNA-seq cohorts. Finally, a separate cohort of tuberculosis patients with functional immune responses was evaluated to clarify stimulated from unstimulated immune responses.ResultsA discovery cohort, including 435 tuberculosis patients and 533 asymptomatic controls, identified two tuberculosis endotypes. Endotype A is characterised by increased expression of genes related to inflammation and immunity and decreased metabolism and proliferation; in contrast, endotype B has increased activity of metabolism and proliferation pathways. An independent RNA-seq validation cohort, including 118 tuberculosis patients and 179 controls, validated the discovery results. Gene expression signatures for treatment failure were elevated in endotype A in the discovery cohort, and a separate validation cohort confirmed that endotype A patients had slower time to culture conversion, and a reduced cure rate. These observations suggest that endotypes reflect functional immunity, supported by the observation that tuberculosis patients with a hyperinflammatory endotype have less responsive cytokine production upon stimulation.ConclusionThese findings provide evidence that metabolic and immune profiling could inform optimisation of endotype-specific host-directed therapies for tuberculosis.

Background Stool is an important diagnostic specimen for tuberculosis in populations who struggle to provide sputum, such as children or people living with HIV. However, the culture of Mycobacterium tuberculosis (M. tuberculosis) complex strains from stool perform poorly. This limits the opportunity for phenotypic drug resistance testing with this specimen. Therefore, reliable molecular methods are urgently needed for comprehensive drug resistance testing on stool specimens. Methods We evaluated the performance of targeted next-generation sequencing (tNGS, Deeplex® Myc-TB) for the detection of mutations associated with M. tuberculosis complex drug resistance on DNA isolated from stool specimens provided by participants from a prospective cohort of patients treated for tuberculosis in Eswatini (n = 66; 56 with and 10 participants without M. tuberculosis complex DNA detected in stool by real-time quantitative PCR), and an independent German validation cohort of participants with culture-confirmed tuberculosis (n = 21). Results The tNGS assay detected M. tuberculosis complex DNA in 38 of 56 (68%) samples; for 28 of 38 (74%) samples, a full M. tuberculosis complex drug resistance prediction report was obtained. There was a high degree of concordance with sputum phenotypic drug susceptibility results (κ = 0.82). The ability to predict resistance was concentration-dependent and successful in 7/10 (70%), 18/25 (72%), and 3/21 (14%) of samples with stool PCR concentration thresholds of > 100 femtogram per microliter (fg/μl), 1 to 100 fg/μl, and < 1 fg/μl, respectively (p = 0.0004). The German cohort confirmed these results and demonstrated a similarly high concordance between stool tNGS and sputum phenotypic drug susceptibility results (κ = 0.84). Conclusions tNGS can identify drug resistance from stool provided by tuberculosis patients. This affords the opportunity to obtain critical diagnostic information for tuberculosis patients who struggle to provide respiratory specimens.

TB disease diagnosis in children is difficult due to non-specific symptoms, paucibacillary disease and the need for invasive procedures to obtain diagnostic specimens. In many settings, these specimens are simply not collected and therefore stool, easily obtained, has emerged as a promising specimen for the diagnosis of child TB. In this study, stool from a healthy adult was spiked with known concentrations of bacille Calmette-Guérin vaccine and tested using the Xpert® Ultra assay to determine the relative detection and error rate associated with four different published stool processing methods.

Background: Tuberculosis (TB) is the archetypical chronic infection, with patients having months of symptoms before diagnosis. In the two years after successful therapy, survivors of TB have a three-fold increased risk of death. Methods: Guinea pigs were infected with Mycobacterium tuberculosis (Mtb) for 45 days, followed by RRBS DNA methylation analysis. In humans, network analysis of differentially expressed genes across three TB cohorts were visualized at the pathway-level. Serum levels of inflammation were measured by ELISA. Horvath (DNA methylation) and RNA-seq biological clocks were used to investigate shifts in chronological age among humans with TB. Results: Guinea pigs with TB demonstrated DNA hypermethylation and showed system-level similarity to humans with TB (p-value = 0.002). The transcriptome in TB in multiple cohorts was enriched for DNA methylation and cellular senescence. Senescence associated proteins CXCL9, CXCL10, and TNF were elevated in TB patients compared to healthy controls. Humans with TB demonstrate 12.7 years (95% CI: 7.5, 21.9) and 14.38 years (95% CI: 10.23-18.53) of cellular aging as measured by epigenetic and gene expression based cellular clocks, respectively. Conclusions: In both guinea pigs and humans, TB perturbs epigenetic processes, promoting premature cellular aging and inflammation, a plausible means to explain the long-term detrimental health outcomes after TB.

Rationale: Host response is a critical factor determining susceptibility to tuberculosis (TB). A delicate balance should be maintained between intracellular immunity against Mycobacterium tuberculosis (Mtb) and minimizing detrimental immunopathology. Studies have identified incongruous immune responses that can lead to a similar TB disease phenotype. Instead of envisioning that susceptibility to TB follows a singular path, we propose the hypothesis that varied host endotypes exist within the TB clinical phenotype. Methods and Results: Unbiased clustering analysis from 12 publicly available gene expression datasets consisting of data from 717 TB patients and 527 controls, identified 4 TB patient endotypes with distinct immune responses. The two largest endotypes exhibit divergent metabolic, epigenetic and immune pathways. TB patient endotype A, comprising 333 TB patients (46.4%), is characterized by increased expression of genes important for i) glycolysis, ii) IL-2-STAT5, IL-6-STAT3, Type I and II Interferon IFN-γ and TNF signaling and iii) epigenetic-modifying genes. In contrast, TB patient endotype B, comprising 313 TB patients (43.6%), is characterized by i) upregulated NFAT and hormone metabolism, and ii) decreased glycolysis, IFN-γ and TNF signaling. In silico evaluation suggests therapies beneficial for endotype A could be detrimental to endotype B, and vice versa. Multiplex ELISA completed from an external validation cohort confirmed a TB patient sub-group with decreased immune upregulation. Conclusions: Host immunity to TB is heterogenous. Unbiased clustering analysis identified distinct TB endotypes with divergent metabolic, epigenetic and immune gene expression profiles that may enable stratified or personalized treatment management in the future.

Mycobacterium tuberculosis (Mtb) has co-evolved with humans for millennia and developed multiple mechanisms to evade host immunity. Restoring host immunity in order to shorten existing therapy and improve outcomes will require identifying the full complement by which host immunity is inhibited. Perturbing host DNA methylation is a mechanism induced by chronic infections such as HIV, HPV, LCMV and schistosomiasis to evade host immunity.Here, we evaluated the DNA methylation status of TB patients and their asymptomatic household contacts demonstrating that TB patients have DNA hyper-methylation of the IL-2-STAT5, TNF-NF-ϰB and IFN-γ signaling pathways. By MSRE-qPCR, multiple genes of the IL-12-IFN-γ signaling pathway (IL12B, IL12RB2, TYK2, IFNGR1, JAK1 and JAK2) were hypermethylated in TB patients. The DNA hyper-methylation of these pathways is associated with decreased immune responsiveness with decreased mitogen induced upregulation of IFN-γ, TNF, IL-6 and IL-1β production. The DNA hyper-methylation of the IL-12-IFN-γ pathway was associated with decreased IFN-γ induced gene expression and decreased IL-12 inducible upregulation of IFN-γ. This work demonstrates that immune cells from TB patients are characterized by DNA hyper-methylation of genes critical to mycobacterial immunity resulting in decreased mycobacteria-specific and non-specific immune responsiveness.