Among respiratory infections, tuberculosis was the second deadliest infectious disease in 2020 behind COVID-19. Inhalable nanocarriers offer the possibility of actively targeting anti-tuberculosis drugs to the lungs, especially to alveolar macrophages (cellular reservoirs of the Mycobacterium tuberculosis). Our strategy was based on the development of a mannose-decorated micellar nanoformulation based in Soluplus^® to co-encapsulate rifampicin and curcumin. The former is one of the most effective anti-tuberculosis first-line drugs, while curcumin has demonstrated potential anti-mycobacterial properties. Mannose-coated rifampicin (10 mg/mL)–curcumin (5 mg/mL)-loaded polymeric micelles (10% w/v) demonstrated excellent colloidal properties with micellar size ~108 ± 1 nm after freeze-drying, and they remain stable under dilution in simulated interstitial lung fluid. Drug-loaded polymeric micelles were suitable for drug delivery to the deep lung with lung accumulation, according to the in vitro nebulization studies and the in vivo biodistribution assays of radiolabeled (99mTc) polymeric micelles, respectively. Hence, the nanoformulation did not exhibit hemolytic potential. Interestingly, the addition of mannose significantly improved (5.2-fold) the microbicidal efficacy against Mycobacterium tuberculosis H37Rv of the drug-co-loaded systems in comparison with their counterpart mannose-free polymeric micelles. Thus, this novel inhaled nanoformulation has demonstrated its potential for active drug delivery in pulmonary tuberculosis therapy.

Interferon gamma (IFNG) plays a key role during Mycobacterium tuberculosis (Mtb) infection, and several polymorphisms located in its gene are associated with risk of tuberculosis in diverse populations. Nevertheless, the genetic resistance/susceptibility to tuberculosis in Argentina is unknown. The IFNG rs1861494 polymorphism (G→A) was reported to alter the binding of transcription factors to this region, influencing IFNG production. Using a case-control study, we found an association between the AA and AG genotypes and tuberculosis resistance (AA vs. GG: odds ratio (OR) = 0.235, p-value = 0.012; AG vs. GG: OR = 0.303, p-value = 0.044; AA vs. AG: OR = 0.776, p-value = 0.427; AA + AG vs. GG: OR = 0.270, p-value = 0.022). Moreover, Mtb-antigen stimulated peripheral blood mononuclear cells (PBMCs) from healthy donors and AA carriers secreted the highest amounts of IFNG in culture supernatants (p-value = 0.034) and presented the greatest percentage of CD4⁺IFNG⁺ lymphocytes (p-value = 0.035), in comparison with GG carriers. No association between the polymorphism and clinical parameters of tuberculosis severity was detected. However, our findings indicate that the rs1861494 single nucleotide polymorphism (SNP) could be considered as a biomarker of tuberculosis resistance in the Argentinean population.

Alterations of myeloid cell populations have been reported in patients with tuberculosis (TB). In this work, we studied the relationship between myeloid-derived suppressor cells (MDSC) and monocytes subsets with the immunological responsiveness of TB patients. Individuals with active TB were classified as low responders (LR-TB) or high responders (HR-TB) according to their T cell responses against a cell lysate of Mycobacterium tuberculosis (Mtb-Ag). Thus, LR-TB, individuals with severe disease, display a weaker immune response to Mtb compare to HR-TB, subjects with strong immunity against the bacteria. We observed that LR-TB presented higher percentages of CD16 positive monocytes as compared to HR-TB and healthy donors. Moreover, monocyte-like (M-MDSC) and polymorphonuclear-like (PMN-MDSC) MDSC were increased in patients and the proportion of M-MDSC inversely correlated with IFN-γ levels released after Mtb-Ag stimulation in HR-TB. We also found that LR-TB displayed the highest percentages of circulating M-MDSC. These results demonstrate that CD16 positive monocytes and M-MDSC frequencies could be used as another immunological classification parameter. Interestingly, in LR-TB, frequencies of CD16 positive monocytes and M-MDSC were restored after only three weeks of anti-TB treatment. Together, our findings show a link between the immunological status of TB patients and the levels of different circulating myeloid cell populations.

Mycobacterium tuberculosis (Mtb), the etiologic agent of tuberculosis (TB), has killed nearly one billion people in the last two centuries. Nowadays, TB remains a major global health problem, ranking among the thirteen leading causes of death worldwide. Human TB infection spans different levels of stages: incipient, subclinical, latent and active TB, all of them with varying symptoms, microbiological characteristics, immune responses and pathologies profiles. After infection, Mtb interacts with diverse cells of both innate and adaptive immune compartments, playing a crucial role in the modulation and development of the pathology. Underlying TB clinical manifestations, individual immunological profiles can be identified in patients with active TB according to the strength of their immune responses to Mtb infection, defining diverse endotypes. Those different endotypes are regulated by a complex interaction of the patient’s cellular metabolism, genetic background, epigenetics, and gene transcriptional regulation. Here, we review immunological categorizations of TB patients based on the activation of different cellular populations (both myeloid and lymphocytic subsets) and humoral mediators (such as cytokines and lipid mediators). The analysis of the participating factors that operate during active Mtb infection shaping the immunological status or immune endotypes of TB patients could contribute to the development of Host Directed Therapy.

Introduction: Mycobacterium tuberculosis , the etiologic agent of tuberculosis (TB), has killed nearly one billion people during the last two centuries. Nowadays, TB remains a major global health problem ranked among the top 10 causes of death worldwide. One of the main challenges in developing new strategies to fight TB is focused on reducing the duration and complexity of drug regimens. Cannabidiol (CBD) is the main nonpsychoactive ingredient extracted from the Cannabis sativa L . plant, which has been shown to be biologically active against bacteria. The purpose of this work was to investigate the antimicrobial effect of CBD on M. tuberculosis intracellular infection. Materials and Methods: To assess the minimum inhibitory concentration (MIC) of CBD on mycobacterial strains, the MTT assay was performed on Mycobacterium smegmatis , and the Colony-Forming Unit (CFU) assay was conducted on Mtb H37Rv. Additionally, the cytotoxic effect of CBD on THP-1 cells was assessed by MTT assay. Moreover, macrophages derived from the THP-1 cell were infected with Mtb H37Rv (multiplicity of infection 1:10) to evaluate the intracellular activity of CBD by determining the CFU/mL. Results: Antimicrobial activity against M. smegmatis (MIC=100 μM) and Mtb H37Rv (MIC=25 μM) cultures was exhibited by CBD. Furthermore, the effect of CBD was also evaluated on Mtb H37Rv infected macrophage cells. Interestingly, a reduction in viable intracellular Mtb H37Rv bacteria was observed after 24 h of treatment. Moreover, CBD exhibited a safe profile toward human THP-1 cells, since it showed no toxicity (CC ₅₀ =1075 μM) at a concentration of antibacterial effect (selectivity index 43). Conclusion: These results extend the knowledge regarding the antimicrobial activity of CBD and demonstrate its ability to kill the human intracellular pathogen M. tuberculosis.

Prostaglandin E2 (PGE2), an active lipid compound derived from arachidonic acid, regulates different stages of the immune response of the host during several pathologies such as chronic infections or cancer. Manipulation of PGE2 levels was proposed as an approach for countering the Type I IFN signature of tuberculosis (TB), but very limited information exists about this pathway in patients with active TB. Here, we demonstrated that PGE2 exerts a potent immunosuppressive action during the immune response of the human host against M. tuberculosis . Thus, we showed that PGE2 inhibited both lymphoproliferation and cytokine production of proinflammatory cytokines, together with a significant reduction of the surface expression of several immunological receptors in human cells. However, PGE2 promoted the autophagic flux of antigen-stimulated monocytes, even in the presence of IFNα. In this way, the attenuation of inflammation and immunopathology caused by an excessive immune response emerges as an attractive therapeutic target. Together, our findings contribute to the knowledge of Mtb -resistance mediated by PGE2 and highlight the potential of this lipid mediator as a tool to improve anti-TB treatment.