Lymphatic endothelial cells are a replicative niche for Mycobacterium tuberculosis
Thomas R. Lerner, … , Gareth Griffiths, Maximiliano G. Gutierrez
Thomas R. Lerner, … , Gareth Griffiths, Maximiliano G. Gutierrez
Published February 22, 2016
Citation Information: J Clin Invest. 2016;126(3):1093-1108. https://doi.org/10.1172/JCI83379.
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Research Article Cell biology Infectious disease

Lymphatic endothelial cells are a replicative niche for Mycobacterium tuberculosis

Abstract

In extrapulmonary tuberculosis, the most common site of infection is within the lymphatic system, and there is growing recognition that lymphatic endothelial cells (LECs) are involved in immune function. Here, we identified LECs, which line the lymphatic vessels, as a niche for Mycobacterium tuberculosis in the lymph nodes of patients with tuberculosis. In cultured primary human LECs (hLECs), we determined that M. tuberculosis replicates both in the cytosol and within autophagosomes, but the bacteria failed to replicate when the virulence locus RD1 was deleted. Activation by IFN-γ induced a cell-autonomous response in hLECs via autophagy and NO production that restricted M. tuberculosis growth. Thus, depending on the activation status of LECs, autophagy can both promote and restrict replication. Together, these findings reveal a previously unrecognized role for hLECs and autophagy in tuberculosis pathogenesis and suggest that hLECs are a potential niche for M. tuberculosis that allows establishment of persistent infection in lymph nodes.

Authors

Thomas R. Lerner, Cristiane de Souza Carvalho-Wodarz, Urska Repnik, Matthew R.G. Russell, Sophie Borel, Collin R. Diedrich, Manfred Rohde, Helen Wainwright, Lucy M. Collinson, Robert J. Wilkinson, Gareth Griffiths, Maximiliano G. Gutierrez

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Figure 4

Autophagy induction by M. tuberculosis and localization in autophagosomes is RD1 dependent.

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Autophagy induction by M. tuberculosis and localization in autophagosome...
(A) Western blot and quantification of whole-cell total protein levels of LC3-II at 48 hours after infection (normalized to actin) in uninfected, M. tuberculosis WT, M. tuberculosis ΔRD1, or M. tuberculosis ΔRD1:comp infected hLEC samples in the presence (red bars) or absence (blue bars) of IFN-γ. Data represent mean ± SEM of at least 3 biological replicates. (B) Same as in A, but p62 levels were measured. (C) Representative images of hLECs infected with M. tuberculosis WT, M. tuberculosis ΔRD1, or M. tuberculosis ΔRD1:comp at 48 hours after infection in the presence or absence of IFN-γ. Images show bacteria expressing EGFP, endogenous LC3-Cy3, F-actin labeled with Alexa Fluor 633–phalloidin, and DNA labeled with DAPI. Scale bar: 10 μm. Original magnification, ×5 (inset). (D) Quantification of the association of LC3 with M. tuberculosis WT, M. tuberculosis ΔRD1, or M. tuberculosis ΔRD1:comp from images such as those in D at 48 hours after infection. N is the total number of individual bacterial entities measured in each condition, and the percentages refer to the proportion of the LC3+ population (i.e., the population within each dotted box). Error bars represent mean ± SEM from 3 biological replicates. ***P < 0.001, 1-way ANOVA with Tukey’s post-hoc test.