The expression of cytoplasmic protein TLR4 and IκB decreased significantly in the COPD model rats compared to the normal rats (P = 0.003, P = 0.007), while the expression of cytoplasmic protein p-IκB and nuclear protein p65 increased significantly (P = 0.008, P = 0.008) (Fig. 8). Here, TLR4 is linked to chronic obstructive pulmonary disease.