Immunological options for the treatment of tuberculosis: evaluation of novel therapeutic approaches

Immunogenicity and protection conferred by Mycobacterium habana in a murine model of pulmonary tuberculosis

Mycobacterium habana was isolated in Cuba in 1971. Later, was demonstrated its protection capacity in mycobacterial infection. Here we determined the level of virulence, immunogenicity and the efficacy of three different M. habana strains as attenuated live vaccines. Intratracheal infection of BALB/c mice with high dose M. habana TMC 5135 or IPK-337 strains permitted 100% survival and limited tissue damage. Mice infected with M. habana IPK-220 showed lower attenuation, so it was discarded for the vaccination experiments. Strains IPK-337 and TMC 5135 were used as subcutaneous vaccine and compared with BCG. Nude mice vaccinated with strain 5135 showed longer but non-significant survival than BCG vaccinated animals. Cell suspensions from M. habana vaccinated mice produced higher IFNγ after stimulation with mycobacterial antigens than BCG recipients. After four months of challenge with Mycobacterium tuberculosis strain H37Rv, mice vaccinated with BCG substrain Phipps or strain TMC 5135 showed total survival, while 60% survival was exhibited by animals vaccinated with M. habana IPK-337. Both M. habana strains do not prevent the infection with M. tuberculosis but avoided the progression of the experimental disease; strain TMC 5135 showed similar level of protection than BCG.

Independent association of younger age with hemoptysis in adults with pulmonary tuberculosis

BACKGROUND

The risk factors for mild to moderate hemoptysis in patients with pulmonary tuberculosis (PTB) are not entirely clear.

OBJECTIVE

To evaluate the independent association of risk factors with the occurrence of hemoptysis in PTB patients.

DESIGN

Cross-sectional study of adult patients newly diagnosed with microbiologically proven PTB in a New York City hospital. Patients were categorized into subjects with and without hemoptysis and compared using univariate analysis. Independent associations of variables with hemoptysis were estimated using multivariate logistic regression.

RESULTS

Of 194 subjects with PTB, 44 (23%) had hemoptysis. In univariate analysis, subjects with hemoptysis were significantly younger (P = 0.003), and more likely to be undocumented foreign-born (P = 0.038) compared to subjects without hemoptysis. In multivariate analysis, only younger age was independently associated with hemoptysis. This association was significant for a continuous decrease in age per year, or per decade (adjusted OR 1.59, P = 0.003).

CONCLUSIONS

Younger age is an independent risk factor for hemoptysis in PTB. It is conceivable that a stronger inflammatory response in younger than in older age could contribute to pulmonary pathogenesis and injury in PTB.

Incipient and subclinical tuberculosis: defining early disease states in the context of host immune response

Latent Mycobacterium tuberculosis infection (LTBI) and active tuberculosis (TB) are 2 ends of a spectrum of states ranging from asymptomatic infection to overt disease. While progressing from LTBI to TB, patients often undergo asymptomatic states with detectable manifestations indicative of disease. Such asymptomatic disease states frequently remain undiagnosed, and their manifestations and duration are mostly dependent on host immune response. Various terms referring to such states are used in the literature, often interchangeably and without explicit definitions. Defining these intermediate states in concrete terms is important for pragmatic reasons, as they might impact upon the diagnostic performance of TB biomarkers and could also present targets for therapeutic interventions. We here propose definitions for 2 commonly used terms, "incipient" and "subclinical" TB, to describe asymptomatic disease states occurring at opposite ends of the host response spectrum. We propose using the term "incipient TB" when referring to early, contained disease in asymptomatic, relatively immunocompetent persons. In contrast, we propose using the term "subclinical TB" to refer to disease in asymptomatic, immunocompromised individuals in whom it is largely associated with loss of effective containment. The rationale for this article is to facilitate the discussion of such early disease states, especially in relation to their impact on TB biomarker discovery and assessment of new diagnostics, and with regard to treatment decisions and ultimately outcome.

Correlation between serum and plasma antibody titers to mycobacterial antigens

The ability to utilize serum or plasma samples interchangeably is useful for tuberculosis (TB) serology. We demonstrate a strong correlation between antibody titers to several mycobacterial antigens in serum versus plasma from HIV-infected and non-HIV-infected TB and non-TB patients (r = 0.99 to 0.89; P < 0.0001). Plasma and serum can be used interchangeably in the same antibody detection assays.