Single cell transcriptomics in blood of patients with chronic obstructive pulmonary disease.

Background: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Single-cell RNA sequencing (scRNA-seq) provides gene expression profiles at the single-cell level. Hence, we evaluated gene expression in the peripheral blood of patients with COPD.

Methods: Peripheral blood samples from seven healthy controls and eight patients with COPD were obtained in this study. The 10X Genomics Chromium Instrument and cDNA synthesis kit were utilized to generate a barcoded cDNA library for single cell RNA-sequencing. We compared the scRNA-seq data between the COPD and control groups using computational analysis. Functional analyses were performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses.

Results: scRNA-seq was used to analyze the transcriptome of peripheral blood mononuclear cells from seven normal controls and eight patients with COPD. We found an increased number of monocyte/macrophages in the COPD group compared to the normal control group. Among the differentially expressed genes (DEGs) in monocyte/macrophages, we identified 15 upregulated genes (EGR1, NR4A1, CCL3, CXCL8, PTGS2, CD83, BCL2A1, SGK1, IL1B, BTG2, NFKBIZ, DUSP2, MAFB, PLAUR and CCL3L1) and 7 downregulated genes (FOLR3, RPS4Y1, HLA-DRB5, NAMPT, CD52, TMEM176A and TMEM176B) in the COPD group compared to the normal control group.

Conclusions: Using scRNA-seq, we found differences in cell type distribution, especially in monocyte/ macrophages. Several upregulated and downregulated genes were found in the monocyte/macrophages of the COPD group.