C3AR1 and chronic obstructive pulmonary disease: Top downregulated genes include vascular gene Apold1, neurotransmitter GAL, and integerin gene Itgad. In CS-exposed mice, 490 DEGs were upregulated, including COPD susceptible gene Mmp12, smoking related gene Npy, apolipoprotein Apol7c, and complement component C3a C3ar1. Extracellular matrix gene Ecm2, and stress related heat shock proteins genes (Hspa1a, Hspa1b), and growth hormone receptor Ghr were amongst the top down-regulated genes.