The observed downregulation of HLA-DRB5 in both Type II Alveolar Epithelial Cells and Microvascular Endothelial Cells during their developmental trajectories, along with the reduced expression of CPED1 in Fibroblasts, is consistent with their overall reduced expression in cancer tissues, highlighting their potential significance in LUAD pathogenesis. The gene discussed is HLA-DRB5; the disease is cancer.