Doxycycline and HIV infection suppress tuberculosis-induced matrix metalloproteinases.

RATIONALE: Tuberculosis kills more than 1.5 million people per year, and standard treatment has remained unchanged for more than 30 years. Tuberculosis (TB) drives matrix metalloproteinase (MMP) activity to cause immunopathology. In advanced HIV infection, tissue destruction is reduced, but underlying mechanisms are poorly defined and no current antituberculous therapy reduces host tissue damage. OBJECTIVES: To investigate MMP activity in patients with TB with and without HIV coinfection and to determine the potential of doxycycline to inhibit MMPs and decrease pathology. METHODS: Concentrations of MMPs and cytokines were analyzed by Luminex array in a prospectively recruited cohort of patients. Modulation of MMP secretion and Mycobacterium tuberculosis growth by doxycycline was studied in primary human cells and TB-infected guinea pigs. MEASUREMENTS AND MAIN RESULTS: HIV coinfection decreased MMP concentrations in induced sputum of patients with TB. MMPs correlated with clinical markers of tissue damage, further implicating dysregulated protease activity in TB-driven pathology. In contrast, cytokine concentrations were no different. Doxycycline, a licensed MMP inhibitor, suppressed TB-dependent MMP-1 and -9 secretion from primary human macrophages and epithelial cells by inhibiting promoter activation. In the guinea pig model, doxycycline reduced lung TB colony forming units after 8 weeks in a dose-dependent manner compared with untreated animals, and in vitro doxycycline inhibited mycobacterial proliferation. CONCLUSIONS: HIV coinfection in patients with TB reduces concentrations of immunopathogenic MMPs. Doxycycline decreases MMP activity in a cellular model and suppresses mycobacterial growth in vitro and in guinea pigs. Adjunctive doxycycline therapy may reduce morbidity and mortality in TB.

Oral delivery of BCG Moreau Rio de Janeiro gives equivalent protection against tuberculosis but with reduced pathology compared to parenteral BCG Danish vaccination.

There is a need for an improved vaccine to better control human tuberculosis (TB), as the only currently available TB vaccine, bacillus Calmette-Guerin (BCG) delivered parenterally, offers variable levels of efficacy. Therefore, recombinant strains expressing additional antigens are being developed alongside alternative routes to parenteral delivery. There is strong evidence that BCG Moreau (RdJ) is a safe and effective vaccine in humans when given by the oral route. This study compared the efficacy of a single oral dose of wild type BCG Moreau Rio de Janeiro (RdJ), or a recombinant RdJ strain expressing Ag85B-ESAT6 fusion protein, formulated with and without lipid to enhance oral delivery, with subcutaneous BCG Danish 1331 and saline control groups in a guinea pig aerosol infection model of pulmonary tuberculosis. Protection was measured as survival at 30 weeks post-challenge and reduced bacterial load and histopathology in lungs and spleen. Results showed that a single oral dose of BCG Moreau (RdJ) or recombinant BCG Moreau (RdJ)-Ag85B-ESAT6, formulated with or without lipid, gave protection equivalent to subcutaneously delivered BCG Danish in the 30 weeks post-challenge survival study. The orally delivered vaccines gave reduced pathology scores in the lungs (three of the four formulations) and spleens (all four formulations) compared to subcutaneously delivered BCG Danish. The oral wild type BCG Moreau (RdJ) in lipid and the unformulated oral wild type BCG Moreau (RdJ) vaccine also gave statistically lower bacterial loads in the lungs and spleens, respectively, compared to subcutaneously delivered BCG Danish. This study provides further evidence to show that lipid formulation does not impair vaccine efficacy and may enhance the delivery and stability of oral vaccines intended for use in countries with poor health infrastructure. Oral delivery also avoids needles (and associated cross-infection risks) and immunisation without the need for specially trained medical professional staff.

Characterisation of a live Salmonella vaccine stably expressing the Mycobacterium tuberculosis Ag85B-ESAT6 fusion protein.

A recombinant Salmonella enterica serovar Typhimurium (S. Typhimurium) vaccine strain was constructed that stably expressed the Mycobacterium tuberculosis fusion antigen Ag85B-ESAT6 from the chromosome. Live oral vaccination of mice with the Salmonella/Ag85B-ESAT6 strain generated a potent anti-Ag85B-ESAT6 T(H)1 response with high antibody titres with a IgG2a-bias and significant IFN-gamma production lasting over a 120-day period. When mice primed with the Salmonella/Ag85B-ESAT6 vaccine were mucosally boosted with the Ag85B-ESAT6 antigen and adjuvant the IFN-gamma responses increased markedly. To determine the protective efficacy of this vaccine strain, guinea pigs were immunised and followed for a 30-week period after aerosol challenge with M. tuberculosis. The heterologous prime-boost strategy of live Salmonella vaccine followed by a systemic boost of antigen and adjuvant reduced the levels of M. tuberculosis bacteria in the lungs and spleen to the same extent as BCG. Additionally, this vaccination regimen was observed to be statistically equivalent in terms of protection to immunisation with BCG. Thus, live oral priming with the recombinant Salmonella/Ag85B-ESAT6 and boosting with Ag85B-ESAT6 plus the adjuvant LTK63 represents an effective mucosal vaccination regimen.