ABCA1, by changing the cholesterol level, ensures the stability of lipid rafts and leads to the activation or deactivation of related proteins, for example, Toll-like receptor TLR4, which regulates the inflammatory response to lipopolysaccharide (LPS) of Gram-negative bacteria and plays an important role in the pathogenesis of COPD. This evidence concerns the gene TLR4 and chronic obstructive pulmonary disease.