SUMMARY
Similar to circulating tumour and immune cells, many blood-borne microbes preferentially “home” to specific vascular sites and tissues during hematogenous dissemination 1–5. For many pathogens, the “postal codes” and mechanisms responsible for tissue-specific vascular tropism are unknown and have been challenging to unravel. Members of the Lyme disease Borreliella burgdorferi species complex infect a broad range of mammalian tissues and exhibit complex strain-, species- and host-specific tissue tropism patterns. Intravenous perfusion experiments and intravital microscopy studies suggest that heterogeneous tissue tropism properties may depend on tissue-specific differences in host and microbial molecules supporting vascular interaction and extravasation. However, interpreting these studies can be complicated because of the immune-protective moonlighting (multitasking) properties of many B. burgdorferi adhesins. Here, we investigated whether B. burgdorferi vascular interaction properties measured by live cell imaging and particle tracking in aorta, bladder, brain, joint and skin microvascular flow chamber models predict strain- and tissue-specific dissemination patterns in vivo These studies identified strain- and endothelial cell type-specific interaction properties that accurately predicted in vivo dissemination of B. burgdorferi to bladder, brain, joint and skin but not aorta, and indicated that dissemination mechanisms in all of these tissues are distinct. Thus, the ability to interact with vascular surfaces under physiological shear stress is a key determinant of tissue-specific tropism for Lyme disease bacteria. The methods and model systems reported here will be invaluable for identifying and characterizing the diverse, largely undefined molecules and mechanisms supporting dissemination of Lyme disease bacteria. These methods and models may be useful for studying tissue tropism and vascular dissemination mechanisms of other blood-borne microbes.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Competing interests. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest The authors declare no competing interests.
Funding Information. Canadian Institutes of Health Research (CIHR) (MOP-119598, CPG-127788, PJT-159466-S); Natural Sciences and Engineering Research Council (NSERC) (RGPIN 401938-11, RGPIN-2017-06403, CHRPJ 446650-13); Canada Foundation for Innovation (27881, IOF 27881). Scholarships: Queen Elizabeth II Graduate Scholarship in Science and Technology (AB), Harron Fellowship (RE), Ontario Graduate Scholarship (RE), University of Toronto Graduate Fellowship (AB, AL, RE)