Lymphatic endothelial cells are a replicative niche for Mycobacterium tuberculosis
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
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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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 5

Autophagy promotes M. tuberculosis growth in resting hLEC.

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Autophagy promotes M. tuberculosis growth in resting hLEC. (A) The growt...
(A) The growth (GFP fluorescence per cell) of M. tuberculosis WT, M. tuberculosis ΔRD1, or M. tuberculosis ΔRD1:comp after 48 hours of infection in hLECs treated or not (control) with 10 mM 3-MA in activated (red symbols) or resting (blue symbols) cells. Error bars represent mean ± SEM of at least 3 biological replicates. (B) The growth (EGFP fluorescence per cell) of M. tuberculosis WT after 48 hours of infection in control cells (SCRAMBLED) or cells with reduced ATG5 protein level (ATG5 KD) in resting (blue symbols) or activating (red symbols) conditions. Error bars represent mean ± SEM of 3 biological replicates. (C) The growth (EGFP fluorescence per cell) of M. tuberculosis WT after 48 hours of infection in control cells (–Rapa) or cells treated with 500 nM rapamycin (+Rapa) in resting (blue symbols) or activating (red symbols) conditions. Error bars represent mean ± SEM of 3 biological replicates. NS = P > 0.05; *P < 0.05, **P < 0.01, ***P < 0.001, 1-way ANOVA with Tukey’s post-hoc test. (D) Images taken from live-cell imaging of LC3-RFP–expressing hLECs infected with M. tuberculosis WT over 5 days in resting conditions. Scale bar: 10 μm. GFP fluorescence was plotted to show growth of the bacteria in an LC3+ compartment. The structure was relocated for serial block-face SEM analysis using a correlative workflow, and the serial electron images were manually segmented and rendered to create a 3D model of the bacteria (green) and the limiting membrane (red). Scale bar: 2.5 μm. See also Supplemental Videos 2 and 3.