TLR4 and chronic obstructive pulmonary disease: Our results showed that the surface protein expression of TLR4, but not of TLR2, was increased in AMs as a response to CS, accompanied with increased inflammatory cytokins secretion in vivo and in vitro, confirming the results of several reports that have demonstrated changes in the expression of TLR4 in the epithelial cells and monocytes of COPD patients [35-37].