Effect of N-acetylcysteine on apoptosis and autophagy of macrophages infected with Mycobacterium tuberculosis

The purpose of this study was to observe the effect of N-acetylcysteine (NAC) on oxidative stress (OS), intracellular Mycobacterium tuberculosis (MTB) load, apoptosis, and autophagy of macrophages infected with H37Rv MTB. In addition, we explored the possible mechanism of action, to provide a rationale for the use of NAC in the treatment of tuberculosis. We divided THP-1 macrophages into four groups: control, control + NAC, H37Rv, and H37Rv + NAC. OS, apoptosis, autophagy and intracellular MTB colony-forming unit (CFU) indexes were measured at 0, 4, 24, and 48 hours, respectively. Then, various indicator changes were systematically compared. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), apoptosis rate, and LC3II/ β-actin ratio in the H37Rv group increased at 4 hours and reached their peak at 48 hours. The ROS and MDA in the H37Rv + NAC group were lower than those in the H37Rv group. CFU in the H37Rv + NAC group increased at 24 hours and decreased at 48 hours after treatment with NAC, relative to the H37Rv group. In addition, the H37Rv + NAC group showed a decrease in LC3II/β-actin ratio 48 hours after NAC treatment, compared to the H37Rv group. MTB infection can lead to an increase in macrophage OS, apoptosis, and autophagy levels. However, after treatment with NAC, the growth of MTB in macrophages is inhibited, and OS and autophagy levels are reduced. The antioxidant effect and inhibitory effect of NAC on MTB are related to MTB-mediated macrophage OS and autophagy.