EastBio: Dissecting the host-pathogen interactions of Burkholderia using modular three-dimensional models of the human lung

Bacterial pathogens have evolved a diverse range of strategies to infect, survive, and replicate within a host. Investigating these host-pathogen interactions can help us to both understand the fundamental biology of how pathogens manipulate and subvert host cells and inform the development of new tools to fight deadly diseases. However, exploring the host-pathogen relationship at a mechanistic level requires model systems that allow us to manipulate both sides of this equation. This is difficult to achieve in vivo, but traditional in vitro models often fail to accurately represent the complexities of a living system. In recent years, three-dimensional microtissue models such as organoids and organ-on-chip systems have revolutionized the way we study health and disease and have been particularly successful at elucidating aspects of biology that are difficult to recapitulate in other model systems, such as the dissemination of virulent bacteria from localized infections to cause severe systemic disease1,2.

We have recently developed simple air-liquid interface models of the human lung to investigate the pathogenesis and systemic dissemination of the emerging tropical disease melioidosis, which is caused by the understudied pathogen Burkholderia pseudomallei. Disseminated melioidosis infections are associated with particularly high morbidity and mortality, but the mechanism of systemic spread remains poorly understood. We propose to enhance and customize our models to make them fully modular and genetically modifiable to investigate the mechanisms of bacterial dissemination. 

This PhD project will use the model organism B. thailandensis to address the following research questions:

1) Do patrolling immune cells play a role in Burkholderia dissemination? Phagocytes including macrophages and dendritic cells have been proposed to play a role in the systemic spread of B. pseudomallei by acting as “trojan horses”. We will construct modular models of the human lung, swapping in and out different host cell types to determine if they contribute to breaching the lung epithelial barrier

2) What host factors are involved in the systemic spread of Burkholderia? We will perform CRISPR/Cas9 mutagenesis to confirm the roles of host genes predicted to contribute to dissemination such as the transmembrane receptor PAR-1 and the scaffold protein IQGAP1

3) How do Burkholderia virulence factors mediate systemic dissemination? Using a panel of bacterial mutants that are attenuated for systemic dissemination, we will apply our modular models to identify which host cells and pathways are subverted by the virulence factors required for dissemination and elucidate the molecular mechanisms of systemic spread