FIB/SEM-based analysis of Borrelia intracellular processing by human macrophages

TY - JOUR

T1 - FIB/SEM-based analysis of Borrelia intracellular processing by human macrophages

AU - Klose, Matthias

AU - Scheungrab, Maximilian

AU - Luckner, Manja

AU - Wanner, Gerhard

AU - Linder, Stefan

N1 - © 2020. Published by The Company of Biologists Ltd.

PY - 2021/2/11

Y1 - 2021/2/11

N2 - Borrelia burgdorferi is the causative agent of Lyme disease, a multisystemic disorder affecting primarily skin, joints and nervous system. Successful internalization and intracellular processing of borreliae by immune cells like macrophages is decisive for the outcome of a respective infection. Here, we use for the first time focused ion beam scanning electron microscopy tomography (FIB/SEM tomography) to visualize the interaction of borreliae with primary human macrophages with high resolution. We report that interaction between macrophages and the elongated and highly motile borreliae can lead to formation of membrane tunnels that extend deeper into the host cytoplasm than the actual phagosome, most probably as a result of partial extrication of captured borreliae. We also show that membrane tubulation at borreliae-containing phagosomes, a process suggested earlier as a mechanism leading to phagosome compaction, but hard to visualize in live cell imaging, is apparently a frequent phenomenon. Finally, we demonstrate that the endoplasmic reticulum (ER) forms multiple STIM1-positive contact sites with both membrane tunnels and phagosome tubulations, confirming the important role of the ER during uptake and intracellular processing of borreliae.

AB - Borrelia burgdorferi is the causative agent of Lyme disease, a multisystemic disorder affecting primarily skin, joints and nervous system. Successful internalization and intracellular processing of borreliae by immune cells like macrophages is decisive for the outcome of a respective infection. Here, we use for the first time focused ion beam scanning electron microscopy tomography (FIB/SEM tomography) to visualize the interaction of borreliae with primary human macrophages with high resolution. We report that interaction between macrophages and the elongated and highly motile borreliae can lead to formation of membrane tunnels that extend deeper into the host cytoplasm than the actual phagosome, most probably as a result of partial extrication of captured borreliae. We also show that membrane tubulation at borreliae-containing phagosomes, a process suggested earlier as a mechanism leading to phagosome compaction, but hard to visualize in live cell imaging, is apparently a frequent phenomenon. Finally, we demonstrate that the endoplasmic reticulum (ER) forms multiple STIM1-positive contact sites with both membrane tunnels and phagosome tubulations, confirming the important role of the ER during uptake and intracellular processing of borreliae.

U2 - 10.1242/jcs.252320

DO - 10.1242/jcs.252320

M3 - SCORING: Journal article

C2 - 33380490

VL - 134

JO - J CELL SCI

JF - J CELL SCI

SN - 0021-9533

IS - 5

M1 - jcs252320

ER -