Abstract: Objective To investigate the characteristics of immune cell subsets in the lung tissues of patients with chronic obstructive pulmonary disease (COPD) and the mechanism of Liuwei Buqi capsule in modulating immune and inflammatory imbalance in COPD. Methods We downloaded COPD-related single-cell RNA sequencing data from Gene Expression Omnibus (GEO) and identified COPD immune cell subsets using the Seurat package in the R software to construct an immune cell subsets-differential genes network. The target genes and active ingredients of Liuwei Buqi capsule were obtained from the Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP), and the Liuwei Buqi capsule-immune cell subsets-target genes network was constructed by mapping the target genes to the differentially expressed genes in each immune cell subset. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed to analyze significantly enriched pathways of the target genes, and the key genes involved in the top 20 pathways were identified. In a rat model of COPD, we investigated the effects of Liuwei Buqi capsule on pulmonary function, lung tissue pathology, serum levels of IL-1β, NF-κB, and TNF-α, and expressions of IKBα, JNK, c-JUN, and c-FOS proteins in the lung tissue. Results A total of 18 immune-related cell subsets, including macrophages and alveolar macrophages, were identified in both COPD patients and healthy control subjects, and the patients with COPD showed significant changes the percentages of macrophages, cDC1, pDC, mast cells, T cells, and mature dendritic cells (P<0.05). Liuwei Buqi capsules targeted multiple immune cell subsets, and the identified target genes were enriched mostly in such immune and inflammation-related signaling pathways as lipids and atherosclerosis, IL-17 signaling pathway, Toll-like receptor signaling pathway, and TNF signaling pathway; the genes CXCL8, IL1B, JUN, NFKBIA, MAPK8, and FOS were the key genes involved in the significantly enriched pathways. In the rat models of COPD, treatment with Liuwei Buqi capsule significantly improved pulmonary function, alleviated lung pathologies, reduced serum levels of IL-1β, TNF-α, and NF-κB (P<0.05) and pulmonary expressions of JNK, c-JUN, and c-FOS (P<0.01) protein, and increased pulmonary expression of IκBα (P<0.01). Conclusion Liuwei Buqi capsule may play an immunomodulatory role by targeting multiple immune cell subsets in the lung tissue of COPD patients.

Key words: chronic obstructive pulmonary disease, Liuwei Buqi capsule, immune and inflammation, single-cell RNA sequencing