Some proteins of M. tuberculosis that localise to the nucleus of THP-1-derived macrophages.

Host-pathogen dialectics in tuberculosis (TB) via DNA-protein interactions are emerging. We investigated whether proteins produced by Mycobacterium tuberculosis (Mtb) could translocate to the host nucleus. Using lysates of nuclei purified from Mtb-infected THP-1-derived macrophages, we identified at least 15 proteins of Mtb-origin by electrophoretic and chromatographic separation and mass spectrometry. Western blotting confirmed time-dependent accumulation of Mtb EF-Tu, GroEL, GroES and MtrA in the host nucleus. MtrA could pull down at least 16 host proteins. Mtb proteins may have moonlighting functions that affect host gene expression.

Particulate pulmonary delivery systems containing anti-tuberculosis agents.

There is renewed interest in delivering anti-tuberculosis (TB) drugs to the lungs by inhalation. Several groups have investigated particulate pulmonary drug delivery formulations containing anti-TB agents, prepared using a variety of design approaches and processes. This review summarizes trends that indicate feasibility and translation of research efforts aimed at developing inhaled therapies for TB. Whereas formulations intended for reconstitution as solutions prior to nebulization can be produced with relative ease, particle engineering for powder formulations is more specialized. Spray drying and emulsion methods used to prepare particulate pulmonary delivery systems of anti-TB agents are compared. Pharmaceutical characterization is outlined. Administration of repeated inhalations to laboratory animals, especially under Animal Biosafety Level-3 (ABSL-3) containment as required for TB research, is another major challenge. Techniques employed by different groups are reviewed in the context of suitability for drug delivery and amenability towards use in ABSL-3 settings. It is concluded that spray drying is suitable for production of inhalable particles, rigorous physicochemical characterization is necessary for developing inhaled therapies as drug products, and pulmonary delivery of formulations containing anti-TB drugs to animals infected with Mycobacterium tuberculosis can best be carried out using handheld devices.

Inhalable microparticles of nitric oxide donors induce phagosome maturation and kill Mycobacterium tuberculosis.

Nitric oxide (NO) kills Mycobacterium tuberculosis (Mtb) in vitro, but gaseous NO is difficult to administer to patients. We evaluated the consequences of intracellular delivery of NO using inhalable microparticles (MP) containing NO donors. MP containing 10% w/w of NO donors alone, or in addition to 25% each of isoniazid (INH) and rifabutin (RFB) in a polylactide-co-glycolide (PLGA) matrix were prepared by spray drying. THP-1-derived macrophages infected with Mtb H37Rv were exposed to MP or soluble NO donors. Phagosome-lysosome fusion (PLF) and bacterial killing were monitored. Colony forming units (cfu) in lungs and spleen of mice infected with a low-dose aerosol and administered inhalations of MP were enumerated. Bacterial DNA in these tissues was estimated by real-time PCR. In vitro studies indicated a bacteriostatic effect of NO donors despite significant enhancement of PLF. Daily inhalation of MP containing 10% diethylenetriamine nitric oxide adduct (DETA/NO) alone reduced log10 cfu in the lungs from 6.1 to 4.4 at the highest dose in four weeks, but did not significantly affect cfu in the spleen. Inhalations of MP containing DETA/NO in combination with INH and RFB significantly (P < 10(-5), ANOVA) reduced cfu in lungs and spleens by 4 log. Gross morphology and histology of the lungs and spleen indicated that inhaled particles were well-tolerated. Inhalable MP containing NO donors need further investigation as an adjunct to standard anti-tuberculosis chemotherapy.

Inhaled microparticles containing clofazimine are efficacious in treatment of experimental tuberculosis in mice.

Inhalable clofazimine-containing dry powder microparticles (CFM-DPI) and native clofazimine (CFM) were evaluated for activity against Mycobacterium tuberculosis in human monocyte-derived macrophage cultures and in mice infected with a low-dose aerosol. Both formulations resulted in 99% killing at 2.5 µg/ml in vitro. In mice, 480 µg and 720 µg CFM-DPI inhaled twice per week over 4 weeks reduced numbers of CFU in the lung by as much as log(10) 2.6; 500 µg oral CFM achieved a log(10) 0.7 reduction.

Inhaled therapies for tuberculosis and the relevance of activation of lung macrophages by particulate drug-delivery systems.

Pathogenic strains of Mycobacterium tuberculosis (Mtb) induce 'alternative activation' of lung macrophages that they colonize, in order to create conditions that promote the establishment and progression of infection. There is some evidence to indicate that such macrophages may be rescued from alternative activation by inhalable microparticles containing a variety of drugs. This review summarizes the experience of various groups of researchers, relating to observations of induction of a number of classical macrophage activation pathways. Restoration of a 'respiratory burst' and upregulation of reactive oxygen species and nitrogen intermediates through the phagocyte oxidase and nitric oxide synthetase enzyme systems; induction of proinflammatory macrophage cytokines; and finally induction of apoptosis rather than necrosis of the infected macrophage are discussed. It is suggested that there is scope to co-opt host responses in the management of tuberculosis, through the route of pulmonary drug delivery.