Mycobacterium tuberculosis programs mesenchymal stem cells to establish dormancy and persistence
Samreen Fatima, … , Sujata Mohanty, Gobardhan Das
Samreen Fatima, … , Sujata Mohanty, Gobardhan Das
Published October 24, 2019
Citation Information: J Clin Invest. 2020;130(2):655-661. https://doi.org/10.1172/JCI128043.
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Concise Communication Infectious disease

Mycobacterium tuberculosis programs mesenchymal stem cells to establish dormancy and persistence

Abstract

Tuberculosis (TB) remains a major infectious disease worldwide. TB treatment displays a biphasic bacterial clearance, in which the majority of bacteria clear within the first month of treatment, but residual bacteria remain nonresponsive to treatment and eventually may become resistant. Here, we have shown that Mycobacterium tuberculosis was taken up by mesenchymal stem cells (MSCs), where it established dormancy and became highly nonresponsive to isoniazid, a major constituent of directly observed treatment short course (DOTS). Dormant M. tuberculosis induced quiescence in MSCs and promoted their long-term survival. Unlike macrophages, where M. tuberculosis resides in early-phagosomal compartments, in MSCs the majority of bacilli were found in the cytosol, where they promoted rapid lipid synthesis, hiding within lipid droplets. Inhibition of lipid synthesis prevented dormancy and sensitized the organisms to isoniazid. Thus, we have established that M. tuberculosis gains dormancy in MSCs, which serve as a long-term natural reservoir of dormant M. tuberculosis. Interestingly, in the murine model of TB, induction of autophagy eliminated M. tuberculosis from MSCs, and consequently, the addition of rapamycin to an isoniazid treatment regimen successfully attained sterile clearance and prevented disease reactivation.

Authors

Samreen Fatima, Shashank Shivaji Kamble, Ved Prakash Dwivedi, Debapriya Bhattacharya, Santosh Kumar, Anand Ranganathan, Luc Van Kaer, Sujata Mohanty, Gobardhan Das

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Figure 1

M.tuberculosis enters dormancy within MSCs through upregulation of the dosR regulon while promoting quiescence in MSCs.

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M.tuberculosis enters dormancy within MSCs through upregulation of the ...
(A) CFU of M. tuberculosis (M.tb) in MSCs and PBMC-derived macrophages. (B) Confocal microscopy images of macrophages and MSCs infected with M. tuberculosis–GFP at 72 hours after infection. Scale bars: 5 μm. Original magnification, ×40. (C) Relative expression of dormancy genes of M. tuberculosis within human MSCs (derived from 5 donors) at 72 hours after infection as compared with log-phase bacteria. (D) Relative expression of replicative genes of M. tuberculosis in human MSCs and human macrophages (derived from PBMCs, from 5 donors) at 72 hours after infection. (E) Relative expression of dormancy genes of M. tuberculosis in CD45–Sca1+ MSCs sorted from bone marrow of infected mice as compared with log-phase bacteria. (F) Relative expression of replicative genes of M. tuberculosis in CD45+CD11b+ macrophages sorted from lungs of infected mice as compared with MSCs. (G) Heatmap showing the relative expression of cell proliferation and quiescence genes in uninfected and M. tuberculosis–infected human MSCs at 48 and 96 hours. (H) Validation of relative expression of cell proliferation and quiescence genes in human MSCs and macrophages (THP-1) as compared with uninfected control at 72 hours. (I) Western blots showing forkhead signaling pathway from uninfected and M. tuberculosis–infected human MSCs at 96 hours. These experiments are representative of 3 independent experiments with triplicate samples (n = 3). Statistical analyses were conducted using 2-way ANOVA followed by Bonferroni’s post hoc test. Error bars represent SEM. ***P < 0.001, **P < 0.01, *P < 0.05. NS, P > 0.05.