Cholesterol depletion in Mycobacterium avium-infected macrophages overcomes the block in phagosome maturation and leads to the reversible sequestration of viable mycobacteria in phagolysosome-derived autophagic vacuoles
Cholesterol depletion in Mycobacterium avium-infected macrophages overcomes the block in phagosome maturation and leads to the reversible sequestration of viable mycobacteria in phagolysosome-derived autophagic vacuoles
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DOI：
10.1111/j.1462-5822.2005.00617.x
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Thilo, L
中科院分区：
文献类型：
--
作者：
de Chastellier, C;Thilo, L
分枝杆菌吞噬进入巨噬细胞需要质膜中存在胆固醇。这表明病原分枝杆菌可能需要胆固醇才能在非成熟吞噬体中随后在细胞内生存。在这里，我们报告了胆固醇消耗对感染鸟分枝杆菌的小鼠骨髓来源的巨噬细胞中预先存在的吞噬体的影响。用甲基-β-环糊精消耗胆固醇导致吞噬体膜和分枝杆菌表面之间的紧密结合松弛，随后与溶酶体融合。由此产生的吞噬溶酶体随后自主执行自噬，不涉及内质网。消耗 5 小时后，完整的分枝杆菌在大型自噬溶酶体中积累。自噬对于含有分枝杆菌的吞噬溶酶体具有特异性，因为它不涉及受感染细胞中含有乳胶珠的吞噬体。补充胆固醇后，分枝杆菌变得越来越与溶酶体膜对齐，从那里它们被单独隔离在具有全方位紧密贴合的吞噬体膜的吞噬体中，并且不再与溶酶体融合。这些观察结果表明，胆固醇消耗（i）导致吞噬体成熟并与溶酶体融合，并且（ii）导致含有分枝杆菌的吞噬溶酶体自主地进行自噬。此外，（iii）分枝杆菌在自噬溶酶体中没有被杀死，并且（iv）胆固醇补充使分枝杆菌能够从自噬吞噬溶酶体中拯救自己，并再次单独驻留在不再与溶酶体融合的吞噬体中。
Phagocytic entry of mycobacteria into macrophages requires the presence of cholesterol in the plasma membrane. This suggests that pathogenic mycobacteria may require cholesterol for their subsequent intra-cellular survival in non-maturing phagosomes. Here we report on the effect of cholesterol depletion on pre-existing phagosomes in mouse bone marrow-derived macrophages infected with Mycobacterium avium. Cholesterol depletion with methyl-beta-cyclodextrin resulted in a loosening of the close apposition between the phagosome membrane and the mycobacterial surface, followed by fusion with lysosomes. The resulting phagolysosomes then autonomously executed autophagy, which did not involve the endoplasmic reticulum. After 5 h of depletion, intact mycobacteria had accumulated in large auto-phagolysosomes. Autophagy was specific for phagolysosomes that contained mycobacteria, as it did not involve latex bead-containing phagosomes in infected cells. Upon replenishment of cholesterol, mycobacteria became increasingly aligned to the lysosomal membrane, from where they were individually sequestered in phagosomes with an all-around closely apposed phagosome membrane and which no longer fused with lysosomes. These observations indicate that, cholesterol depletion (i) resulted in phagosome maturation and fusion with lysosomes and (ii) caused mycobacterium-containing phagolysosomes to autonomously undergo autophagy. Furthermore, (iii) mycobacteria were not killed in auto-phagolysosomes, and (iv) cholesterol replenishment enabled mycobacterium to rescue itself from autophagic phagolysosomes to again reside individually in phagosomes which no longer fused with lysosomes.