Mycobacterium tuberculosis reside only inside phagosomes in alveolar macrophages of tuberculosis patients

M. tuberculosis (Mtb), the causative agent of tuberculosis (TB), is spread through aerosols and taken up by alveolar macrophages, where pathogen is internalized in phagosomes for survival and persistence. It had been recently reported that Mtb vacuole-to-cytosol escape is required for Mtb replication and dissemination in TB disease progress. We isolated alveolar macrophages from the resected lungs of patients with pulmonary TB and found the large number of viable cells with Mtb as single and in colonies, including with cord morphology (Ufimtseva, E. et al. PLOS ONE 2018; 13:e0191918).For detecting the location of Mtb in TB patients’ alveolar macrophages we applied fluorescence microscopy assay of phagosomal integrity, based on the use of digitonin to label Mtb (primary antibodies to Mtb lipoarabinomannan) that are in cytosol or within disrupted phagosomes, and, then, microscopy assay of same macrophages as in fluorescent images re-stained for acid-fast Mtb by the Ziehl-Neelsen method.Our results document that Mtb with different virulence, as single and in colonies, including with cord morphology, are exclusively intravacuolar pathogens in healthy alveolar macrophages of studied TB patients (Fig. 1).Fig. 1. The lack of Mtb (white arrow) in left image and the presence of Mtb (black arrow) in the same host cell in right image indicate the phagosomal location of Mtb in alveolar macrophage of patient 6.
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: Tuberculosis Source Type: research