The W-Beijing strain family is globally distributed and is associated with multidrug-resistant tuberculosis (TB) and treatment failure. Therefore, in this study, we examined the contribution of Toll-like receptor 2 (TLR2) to host resistance against Mycobacterium tuberculosis HN878, a clinical isolate belonging to the W-Beijing family. We show that TLR2 knockout (TLR2KO) mice infected with M. tuberculosis HN878 exhibit increased bacterial burden and are unable to control tissue-damaging, pulmonary neutrophilic inflammation. Consistent with a critical role for CXCL5 in regulating neutrophil influx, expression of epithelial cell-derived CXCL5 is significantly enhanced in TLR2KO mice prior to their divergence from wild-type (WT) mice in M. tuberculosis replication and neutrophilic inflammation. Depletion of neutrophils in TLR2KO mice by targeting Ly6G reverts lung inflammation and bacterial burden to levels comparable to those of WT mice. Together, the results establish that TLR2 controls neutrophil-driven immunopathology during infection with M. tuberculosis HN878 infection, likely by curtailing CXCL5 production.

Mycobacterium tuberculosis (Mtb) secretes extracellular vesicles (EVs) containing a variety of proteins, lipoproteins, and lipoglycans. While emerging evidence suggests that EVs contribute to tuberculosis pathogenesis, the factors and molecular mechanisms involved in mycobacterial EV production have not been identified. In this study, we use a genetic approach to identify Mtb proteins that mediate vesicle release in response to iron limitation and antibiotic exposure. We uncover a critical role for the isoniazid‐induced, dynamin‐like proteins, IniA and IniC, in mycobacterial EV biogenesis. Further characterization of a Mtb iniA mutant shows that the production of EVs enables intracellular Mtb to export bacterial components into the extracellular environment to communicate with host cells and potentially modulate the immune response. The findings advance our understanding of the biogenesis and functions of mycobacterial EVs and provide an avenue for targeting vesicle production in vivo.

In this study we employed C3HeB/FeJ mice as an experimental model to investigate the potential role of rapamycin, an mTOR inhibitor, as an adjunctive therapy candidate during the treatment of Mycobacterium tuberculosis infection with moxifloxacin. We report that administration of rapamycin with or without moxifloxacin reduced infection-induced lung inflammation, and the number and size of caseating necrotic granulomas. Results from this study strengthen the potential use of rapamycin and its analogs as adjunct TB therapy and importantly underscore the utility of the C3HeB/FeJ mouse model as a pre-clinical tool to evaluate HDT candidates in TB treatment.

SUMMARY SETTING: Accurate testing and treatment for latent tuberculosis infection is necessary for tuberculosis elimination. Certain parasite infections are associated with increased tuberculin skin test positivity; species-specific effects on QuantiFERON-TB Gold In-Tube (QGIT) are not yet described. OBJECTIVE: We sought to determine whether infection with helminths or protozoa affects QGIT results. DESIGN: We retrospectively analyzed QGIT and parasite testing results for immigrants screened in Boston from 2012–2017. We also prospectively measured cytokines in QGIT supernatants for a subset (n=68) with 1) helminths, 2) Blastocystis hominis, 3) other protozoa, and 4) no parasites. RESULTS: Of 527 immigrants screened, 141 (26.8%) had a positive QGIT and 229 (43.4%) had parasites detected: 27/527 (5.1%) helminths and 202/527 (38.3%) protozoa. Cytokine analysis revealed increased IL-10 concentrations with protozoa (p=0.04), and non-significantly higher Th2 concentrations with helminths compared to no parasites. No significant differences emerged in QGIT positivity or interferon-gamma concentrations in any group. CONCLUSION: This study supports use of QGITs in parasite-endemic settings.