Functional vulnerability of liver macrophages to capsules defines virulence of blood-borne bacteria.

Many encapsulated bacteria use capsules to cause invasive diseases. However, it remains largely unknown how the capsules enhance bacterial virulence under in vivo infection conditions. Here we show that the capsules primarily target the liver to enhance bacterial survival at the onset of blood-borne infections. In a mouse sepsis model, the capsules enabled human pathogens Streptococcus pneumoniae and Escherichia coli to circumvent the recognition of liver-resident macrophage Kupffer cells (KCs) in a capsular serotype-dependent manner. In contrast to effective capture of acapsular bacteria by KCs, the encapsulated bacteria are partially (low-virulence types) or completely (high-virulence types) "untouchable" for KCs. We finally identified the asialoglycoprotein receptor (ASGR) as the first known capsule receptor on KCs to recognize the low-virulence serotype-7F and -14 pneumococcal capsules. Our data identify the molecular interplay between the capsules and KCs as a master controller of the fate and virulence of encapsulated bacteria, and suggest that the interplay is targetable for therapeutic control of septic infections. © 2022 An et al.

Citation

Haoran An, Chenyun Qian, Yijia Huang, Jing Li, Xianbin Tian, Jiaying Feng, Jiao Hu, Yujie Fang, Fangfang Jiao, Yuna Zeng, Xueting Huang, Xianbin Meng, Xue Liu, Xin Lin, Zhutian Zeng, Martin Guilliams, Alain Beschin, Yongwen Chen, Yuzhang Wu, Jing Wang, Marco Rinaldo Oggioni, John Leong, Jan-Willem Veening, Haiteng Deng, Rong Zhang, Hui Wang, Jiang Wu, Yan Cui, Jing-Ren Zhang. Functional vulnerability of liver macrophages to capsules defines virulence of blood-borne bacteria. The Journal of experimental medicine. 2022 Mar 08;219(4)

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PMID: 35258552

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