Asthma affects 1 in 8 Canadian children and is the leading cause of pediatric hospitalizations with costs to Canadian health caresystems estimated to exceed 4.2Billion/year by 2030. While the causes are still debated, infant prematurity is a strong predictor forasthma. The altered gut bacterial community (microbiome) in preemies is suspected to contribute to asthma susceptibility bymiscommunicating with regions of the brain that control stress and inflammation in the body, including microglia immune cells.Malfunctioning microglia may thus contribute to stress and inflammation that leads to asthma.Our project will examine the contributing role of microglia in controlling stress activity, immune development and functioning andasthma susceptibility of newborn mice, by altering their microbiome using early-life chronic stress, antibiotics and preemie fecal transplant exposures. Microglia will also be genetically target-eliminated to verify their critical function in stress-mediated asthmaactivation. Finally, we will also examine the therapeutic potential for probiotics developed by Lallemand Health Solutions to repairmicroglia and prevent asthma by normalizing the microbiome and the communication pathways to the brain.Our results will provide Lallemand with important therapeutic information about their probiotics to ameliorate stress pathways andasthma, which will help them improve and develop targeted probiotic formulations.