The mean emphysema score increased as TLR4 expression decreased; the mean emphysema scores of the high, intermediate, and low expressers were 3.63 ± 4.77, 4.92 ± 4.60, and 8.33 ± 5.26, respectively (P = 0.02, Figure3A). Here, TLR4 is linked to pulmonary emphysema.