Effects of cigarette smoke on the administration of isoniazid and rifampicin to macrophages infected with Mycobacterium tuberculosis

Abstract

Background

Smoking is a cause behind many diseases, including tuberculosis, and it is a risk factor for tuberculosis infection and mortality. Moreover, smoking is associated with a poor tuberculosis treatment outcome.

Objectives

In this study, we focus on the effects of cigarette smoke on an infected cell culture treated with anti-tuberculosis drugs.

Materials and methods

Cytotoxicity on THP-1, J774A.1 and MH-S cell lines and growth of Mycobacterium tuberculosis exposed to a reference or a commercial cigarette was evaluated. THP-1 cell line was exposed to cigarette smoke, infected with Mycobacterium tuberculosis and treated with anti-tuberculosis drugs. Apoptosis and death cell were also tested on M. bovis BCG infected cells. Minimal inhibitory concentrations of anti-tuberculosis drugs were analyzed.

Results

All cells lines showed viability values higher than 80% when exposed to cigarette smoke extract. However, THP-1 cell line infected with M. bovis BCG and exposed to Marlboro cigarette smoke showed up to a 54% reduction of apoptotic cells than cells unexposed to smoke. M. tuberculosis exposed to Marlboro cigarette smoke for 11 days had an optical density 16% lower than unexposed bacteria. When cells were infected with M. tuberculosis, the intracellular recovery of CFUs showed up to a 0.66 log reduction in cells exposed to cigarette smoke extract because of a potential impairment in the phagocytosis. Macrophages treated with drugs showed up to a 2.55 log reduction in the intracellular load burden compared with non-treated ones. Despite poor treatment outcome on TB smoker patients, minimal inhibitory concentration of rifampicin increased only 2-fold in M. tuberculosis exposed to cigarette smoke.

Conclusion

Smoking interferes with tuberculosis treatment impairing the immunity of the host.

Keywords:

• Cigarette smoke
• phagocytosis
• Mycobacterium tuberculosis
• drugs

Acknowledgments

José Domínguez is an investigator of the Program Miguel Servet from Instituto de Salud Carlos III and Pablo Rodríguez-Fernández is the recipient of a fellowship from the Spanish Ministry of Science, Innovation and Universities, as a part of the Program Training of University Staff (FPU14/01854). We are also grateful to Bárbara Molina for her technical support, Juan Camilo Nieto for his comments on the manuscript and the Servei de Cultius Cel·lulars, Producció d’Anticossos I Citometria (UAB) for cell culture facilities, use of flux cytometry and assistance.

Additional information

Funding

This work was supported by: SEPAR (Spanish Society for Pulmonology and Thoracic Surgery; Extraordinary Call for Research PII Smoking, Research Project no.: 16/024); European Respiratory Society Long-Term Research Fellowship (LTRF-2015-5934); Instituto de Salud Carlos III (PI16/1912 y PI17/01139 projects, integrated in the National Plan R + D + I and funded by the ISCIII and the European Regional Development Fund) and the CERCA Programme/Generalitat de Catalunya.