More importantly, among the signals sent by macrophages, SPP1-CD44, SPP1-(ITGA4+ITGB1), LGALS9-P4HB, LGALS9-CD45, and LGALS9-CD44 were upregulated in COPD compared to HS (Figure 7H). The gene discussed is ITGA4; the disease is chronic obstructive pulmonary disease.