By co-treatment of inhibitors of TLR4, Syk, PKC, and NF-κB p65 with the PLE respectively, an additive inhibition of inflammatory mediators, such as NO, IL-6, and TNF-α, was exhibited, indicating that TLR4, Syk, PKC, and NF-κB p65 can contribute to PLE treatment alleviating COPD airway inflammatory mediator generation. Here, TLR4 is linked to chronic obstructive pulmonary disease.