N-acetyl-cysteine exhibits potent anti-mycobacterial activity in addition to its known anti-oxidative functions

Author(s)

Amaral, Eduardo P. ; Conceicao, Elisabete L. ; Costa, Diego L. ; Rocha, Michael S. ; Marinho, Jamocyr M. ; Cordeiro-Santos, Marcelo ; D'Imperio-Lima, Maria Regina ; Barbosa, Theolis ; Sher, Alan ; Andrade, Bruno B.

• Document type: Journal article
• Source: BMC Microbiology; v. 16, OCT 28 2016.
• Web of Science Citations: 14

Abstract

Background: Mycobacterium tuberculosis infection is thought to induce oxidative stress. N-acetyl-cysteine (NAC) is widely used in patients with chronic pulmonary diseases including tuberculosis due to its mucolytic and anti-oxidant activities. Here, we tested whether NAC exerts a direct antibiotic activity against mycobacteria. Methods: Oxidative stress status in plasma was compared between pulmonary TB (PTB) patients and those with latent M. tuberculosis infection (LTBI) or healthy uninfected individuals. Lipid peroxidation, DNA oxidation and cell death, as well as accumulation of reactive oxygen species (ROS) were measured in cultures of primary human monocyte-derived macrophages infected with M. tuberculosis and treated or not with NAC. M. tuberculosis, M. avium and M. bovis BCG cultures were also exposed to different doses of NAC with or without medium pH adjustment to control for acidity. The anti-mycobacterial effect of NAC was assessed in M. tuberculosis infected human THP-1 cells and bone marrow-derived macrophages from mice lacking a fully functional NADPH oxidase system. The capacity of NAC to control M. tuberculosis infection was further tested in vivo in a mouse (C57BL/6) model. Results: PTB patients exhibited elevated levels of oxidation products and a reduction of anti-oxidants compared with LTBI cases or uninfected controls. NAC treatment in M. tuberculosis-infected human macrophages resulted in a decrease of oxidative stress and cell death evoked by mycobacteria. Importantly, we observed a dose-dependent reduction in metabolic activity and in vitro growth of NAC treated M. tuberculosis, M. avium and M. bovis BCG. Furthermore, anti-mycobacterial activity in infected macrophages was shown to be independent of the effects of NAC on the host NADPH oxidase system in vitro. Short-term NAC treatment of M. tuberculosis infected mice in vivo resulted in a significant reduction of mycobacterial loads in the lungs. Conclusions: NAC exhibits potent anti-mycobacterial effects and may limit M. tuberculosis infection and disease both through suppression of the host oxidative response and through direct antimicrobial activity. (AU)

• FAPESP's process: 13/07298-5 - Evaluation of the involvement of lysosomal cathepsins in the NLRP3-inflammasome activation induced by recombinant ESAT-6 from Mycobacterium tuberculosis
• Grantee: Eduardo Pinheiro Amaral
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 10/51150-4 - Animal model for analysis of the pathogenicity of Mycobacterium bovis strains and evaluation of cellular and humoral immune responses against pathogenic isolates
• Grantee: Maria Regina D'Império Lima
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/19126-0 - Evaluation of the role of P2X7 receptor for pulmonary macrophage activation and cell death during aggressive forms of Tuberculosis.
• Grantee: Eduardo Pinheiro Amaral
• Support Opportunities: Scholarships in Brazil - Post-Doctoral