Visualization of the Dynamics of Invasion and Intravasation of the Bacterium That Causes Lyme Disease in a Tissue Engineered Dermal Microvessel Model

Lyme disease is a tick-borne disease prevalent in North America, Europe, and Asia. Despite the accumulated knowledge from epidemiological, in vitro, and in animal studies, the understanding of dissemination of vector-borne pathogens, such as Borrelia burgdorferi (Bb), remains incomplete with several important knowledge gaps, especially related to invasion and intravasation into circulation. To elucidate the mechanistic details of these processes a tissue-engineered human dermal microvessel model is developed. Fluorescently labeled Bb are injected into the extracellular matrix (ECM) to mimic tick inoculation. High resolution, confocal imaging is performed to visualize the sub-acute phase of infection. From analysis of migration paths no evidence to support adhesin-mediated interactions between Bb and ECM components is found, suggesting that collagen fibers serve as inert obstacles to migration. Intravasation occurs at cell-cell junctions and is relatively fast, consistent with Bb swimming in ECM. In addition, it is found that Bb alone can induce endothelium activation, resulting in increased immune cell adhesion but no changes in global or local permeability. Together these results provide new insight into the minimum requirements for Bb dissemination and highlight how tissue-engineered models are complementary to animal models in visualizing dynamic processes associated with vector-borne pathogens.

Automated summary

This study investigated the dissemination mechanism of Borrelia burgdorferi using a tissue-engineered human dermal microvessel model. The results showed that collagen fibers acted as inert obstacles to the migration of B. burgdorferi, and intravasation occurred at cell-cell junctions. The study also found that B. burgdorferi alone could induce endothelium activation. These findings provide new insights into the dissemination of B. burgdorferi and the use of tissue-engineered models in studying vector-borne pathogens.