Development and validation of a 3D cell culture model of the tuberculosis granuloma that can be applied for drug discovery and host cellular studies in the context of a latent infection and multicellular immunologic response

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis (Mtb) that latently infects one-quarter of the human population. The lack of an effective vaccine, the lack of reliable biomarkers for latent infection and fast diagnosis, and the limited number of effective antimicrobial drugs, together with the evolution of multi-drug resistant Mtb strains, continue to challenge and delay the achievement of global TB control goals. Granulomas constitute the hallmark of latent TB and a major challenge for TB treatment and the development of new therapies. These stratified multicellular structures that contain the infection constitute a physical barrier for drug delivery and a physiologic limitation since inside the granuloma, bacteria undergo a low to no-replication program, rendering them non-responsive and more resistant to current antibiotics. A greater understanding of granuloma biology will aid the discovery of novel therapeutics or repurposed drugs active in this environment. With this proposal, we aim to generate a 3D model of the TB granuloma that mimics those conditions. We will use primary human cells and microspheres to generate a stratified granuloma model. We will validate this artificial granuloma, showing that its environment replicates human granulomas, that the bacteria are in a state of dormancy and that the host cells are producing a controlled inflammatory response. Finally, we shall demonstrate the utility of the proposed model by testing current drugs used in TB therapeutic. The expected result of this project will be the generation and validation of a new model for the TB granuloma that can be used as a platform for drug discovery and host immune response studies.