PROJECT SUMMARY/ABSTRACT A severe asthma endotype involving neutrophils infiltrating the airways with a Th17 dominant milieu, and excessive airway remodeling and resistance to conventional therapies, has emerged in patients in the past years. In a transcriptomic screen, we found that the TNF Superfamily member LIGHT, was highly enriched in a murine model of severe asthma mimicking the human disease, in addition to being enriched in the sputum of patients. This proposal will evaluate the contribution of LIGHT signaling in 1) neutrophils to promote airway neutrophilia, 2) stromal cells to promote pathological remodeling and steroid resistance, and 3) it will evaluate the pathogenic role of Th17 cells as drivers of airway remodeling compared to Th2 cells, through LIGHT production. Furthermore, we have evidence that the TNF Superfamily LIGHT decreases airway remodeling and will address how LIGHT blockade compares to neutrophilic depletion, or IL17 neutralization, in decreasing NA symptoms: airway resistance, epithelial damage, fibroblasts activation, and neutrophil recruitment. Lastly, this project will address whether the combinatorial blockade of LIGHT and steroid treatment, can abrogate airway remodeling in severe asthma, in the mouse model and the human lung-in-a-dish model we established.