Evidence for the Presence of Borrelia burgdorferi Biofilm in Infected Mouse Tissues

Borrelia burgdorferi, the causative agent of Lyme disease (LD) has been previously shown to form an antimicrobial-resistant aggregation, called biofilm, a structure known to protect the microorganisms from unfavorable conditions. B. burgdorferi biofilms were found in vitro and in vivo with inflammatory markers which are the most common clinical sign of LD. The potential association between Borrelia biofilms and inflammation is yet to be further studied and for that, there is a need for a suitable model organism. To date B. burgdorferi biofilms were only shown in human tissues, therefore, the goal of this thesis was to investigate the connection B. burgdorferi biofilms on the host tissue physiology using a mouse model. Archived B. burgdorferi infected mouse tissues were evaluated for the presence of biofilms using immunohistochemistry (IHC), combined in situ/IHC, and atomic force microscopy techniques. The obtained results showed that in certain tissues, such as brain, heart and kidney, B. burgdorferi indeed forms aggregates with a known biofilm marker. The potential connection of B. burgdorferi biofilms and inflammation was further studied in the infected heart tissues by using C-reactive protein-specific IHC methods The results showed that the C-reactive protein expressed in proximity to Borrelia biofilms, suggesting a potential role of biofilms in promoting inflammatory responses. In summary, this research demonstrated that B. burgdorferi can form biofilms in various mouse tissues and induce inflammatory processes, therefore mouse model can be used for future biofilm research.