TLR4 and inflammation: The makeup of gut microbiota has a significant impact on the development of COPD caused by cigarette smoke, and fecal microbiota transplantation can reverse the progression of COPD. Pg was isolated and found to improve COPD by reducing inflammation in the intestines, boosting mitochondrial and ribosomal functions in the colon, correcting abnormal host amino acid metabolism in the blood, and mitigating lung inflammation. The lipopolysaccharides (LPS) from Pg have anti-inflammatory effects and greatly improve COPD by inhibiting the toll-like receptor 4 (TLR4) signaling pathway.