To examine the macrophage response to M. avium, I compared inflammasome and cytosolic sensor expression and activation. My result demonstrated that virulent strains of M. avium (A5 and 104) suppress IL-1β production and induce IFN-β production in macrophages. M. avium mutants deficient at DNA export in the biofilm exhibited reduced intracellular survival and significantly higher IL-1β production than wildtype. IFN-β production appeared to be related to DNA export capability. To further characterize MGCs, we developed a novel in vitro model which is comprised of a human-derived cell line (THP-1) and cytokine stimulation (IFN-γ and TNF-α). Examination of MGCs with transmission electron microscopy uncovered increased lipid droplets and elevated autophagy. My results showed that M. avium survived and replicated in MGCs and that host lipids play a role in intracellular replication. MGC-passaged bacteria were readily phagocytosed and exhibited normal intracellular replication. The mechanism of cell exit is still unclear. The data presented in this dissertation significantly advance our understanding of the macrophage response to M. avium, and the features of MGCs, and how they interact with M. avium. Understanding these host-pathogen interactions has implications for NTM treatment. The idea that eDNA influences intracellular survival and anti-inflammatory signaling needs further study. However, DNA export genes could be a useful target for future therapies
