We investigated whether the pro-inflammatory T cell cytokines interleukin-17 (IL-17) and IL-22 are induced by human mycobacterial infection. Remarkably, >20% of specific cytokine-producing CD4+ T cells in peripheral blood of healthy, mycobacteria-exposed adults expressed IL-17 or IL-22. Specific IL-17 and IL-22 producing CD4+ T cells were distinct from each other and from Th1 cytokine-producing cells. These cells had phenotypic characteristics of long-lived central memory cells. In patients with tuberculosis disease, peripheral blood frequencies of these cells were reduced, while bronchoalveolar lavage fluid (BALF) contained higher levels of IL-22 protein, compared with healthy controls. IL-17 was not detected in this fluid, which may be due to suppression by Th1 cytokines, as PBMC IL-17 production was inhibited by IFN-γ in vitro. However, Th1 cytokines had no effect on IL-22 production in vitro. Our results imply that the magnitude and complexity of the anti-mycobacterial immune response have historically been underestimated. IL-17 and IL-22-producing CD4+ T cells may play important roles in the human immune response to mycobacteria.

Tuberculosis (TB) remains the top killer from an infectious globally causing an estimated 1.674.000 million deaths worldwide. In 2016, WHO estimates 600.000 cases of rifampicin-resistant TB of which 490.000 had multidrug-resistant (MDR) and less than half of them survive after receiving currently recommended WHO treatment regimens, illustrating weaknesses in current treatment approaches. We review progress and advances in the development of new and repurposed TB drugs, treatment trials and host-directed therapies. Updates are provided on phase 3 trials of the new compounds bedaquiline, delamanid, pretomanid; phase 2 trials of sutezolid, SQ-109, LCB01-0371, PBTZ-169; and five new drugs in phase 1 development. Approved or repurposed drugs undergoing further testing are rifampicin, rifapentine, clofazimine, and linezolid. Update on ongoing clinical trials, which aim to shorten TB treatment and improve treatment outcome is given. Several new or repurposed antimicrobial drugs are in advanced trial stages for MDR-TB, and five antimicrobial drug candidates are in phase 1 (Q203, TBI-166, OPC-167832, GSK 070, TBA-7371) and 5 in pre-clinical studies. Specific issues of safety and toxicity; drug-drug interactions; Therapeutic Drug Monitoring are reviewed. A wide range of candidate host-directed therapies (HDTs) and immune-based treatments are being investigated to accelerate the eradication of M.tb infection and for use as adjunctive therapy in shortening duration of treatment, preventing permanent lung injury and improving treatment outcomes of MDR-TB. Ongoing clinical trials of HDTs for TB treatment, the current HDT development pipeline and translational research efforts for advancing further HDT options are presented. Ongoing clinical trials of HDTs for TB treatment, the current HDT development pipeline and translational research efforts for advancing further HDT options are presented.5

Rationale: Contacts of patients with tuberculosis (TB) constitute an important target population for preventive measures because they are at high risk of infection with Mycobacterium tuberculosis and progression to disease.Objectives: We investigated biosignatures with predictive ability for incident TB.Methods: In a case-control study nested within the Grand Challenges 6-74 longitudinal HIV-negative African cohort of exposed household contacts, we employed RNA sequencing, PCR, and the pair ratio algorithm in a training/test set approach. Overall, 79 progressors who developed TB between 3 and 24 months after diagnosis of index case and 328 matched nonprogressors who remained healthy during 24 months of follow-up were investigated. Measurements and Main Results:A four-transcript signature derived from samples in a South African and Gambian training set predicted progression up to two years before onset of disease in blinded test set samples from South Africa, the Gambia, and Ethiopia with little population-associated variability, and it was also validated in an external cohort of South African adolescents with latent M. tuberculosis infection. By contrast, published diagnostic or prognostic TB signatures were predicted in samples from some but not all three countries, indicating site-specific variability. Post hoc meta-analysis identified a single gene pair, C1QC/TRAV27 (complement C1q C-chain / T-cell receptor-a variable gene 27) that would consistently predict TB progression in household contacts from multiple African sites but not in infected adolescents without known recent exposure events.Conclusions: Collectively, we developed a simple whole blood-based PCR test to predict TB in recently exposed household contacts from diverse African populations. This test has potential for implementation in national TB contact investigation programs.