P66 is a bacterial mimic of CD47 that binds the anti-phagocytic receptor SIRPα and facilitates macrophage evasion by Borrelia burgdorferi, 2024

Abstract
Innate immunity, the first line of defense against pathogens, relies on efficient elimination of invading agents by phagocytes. In the co-evolution of host and pathogen, pathogens developed mechanisms to dampen and evade phagocytic clearance.

Here, we report that bacterial pathogens can evade clearance by macrophages through mimicry at the mammalian anti-phagocytic signaling axis between CD47 (ligand) and SIRPα (receptor). We identified a protein, P66, on the surface of Borrelia burgdorferi that, like CD47, is necessary and sufficient to bind the macrophage receptor SIRPα. Expression of the gene encoding the protein is required for bacteria to bind SIRPα or a high-affinity CD47 reagent. Genetic deletion of p66 increases phagocytosis by macrophages. Blockade of P66 during infection promotes clearance of the bacteria.

This study demonstrates that mimicry of the mammalian anti-phagocytic protein CD47 by B. burgdorferi inhibits macrophage-mediated bacterial clearance. Such a mechanism has broad implications for understanding of host-pathogen interactions and expands the function of the established innate immune checkpoint receptor SIRPα.

Moreover, this report reveals P66 as a novel therapeutic target in the treatment of Lyme Disease.

https://www.biorxiv.org/content/10.1101/2024.04.29.591704v1

 

How thrilling to see this online after 8 years in the works!!! We showed that #Lyme bacteria mimic our own“don’t eat me” signal with their P66 protein to hide in plain sight!!! This tricks our SIRPa protein to trigger the breaks on immune clearance!
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