Objective: To analyze the differentially expressed gene (DEG) in rats with sepsis-induced exogenous acute respiratory distress syndrome (ARDS) and explore the early diagnosis and protective mechanism of sepsis-induced ARDS at the transcriptome level.
Methods: Twelve 6 to 8 weeks old male Sprague-Dawley (SD) rats were randomly divided into lipopolysaccharide (LPS) induced sepsis-induced ARDS model group (model group, intraperitoneal injection of LPS 15 mg/kg) and control group (intraperitoneal injection of the same volume of normal saline), with 6 rats in each group. RNA was extracted from the left lung tissue of the two groups, and the paired-end sequencing mode of the illumina Hiseq sequencing platform was used for high-throughput sequencing. The DESeq2 software was used to screen DEG with |log2 (fold change, FC)| ≥ 3 and P < 0.001. Gene ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed on DEG. STRING and CytoScape software were used to construct a protein-protein interaction (PPI) network and screen key genes. The peripheral blood mononuclear cell (PBMC) of 20 septic patients admitted to the emergency and critical care medical department of Lianyungang First People's Hospital from March to November 2021 and 20 age-matched healthy people in the same period were isolated and extracted, and the key genes were verified by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR).
Results: A total of 286 DEG were screened, including 202 up-regulated genes and 84 down-regulated genes. GO enrichment analysis showed that DEG was mainly involved in biological processes such as neutrophil chemotaxis migration, antibacterial humoral response, host immune response, and humoral immune response. KEGG analysis showed that DEG mainly played a biological role through interleukin-17 (IL-17) signaling pathway, tumor necrosis factor (TNF) signaling pathway, and chemokine signaling pathway. In PPI analysis, a total of 262 node proteins were screened, and the interaction relationship was 852 edges. The first 15 key genes were IL-6, TNF, IL-10, IL-1β, chemokine ligand 1 (CXCL1), CXCL10, chemokine receptor 3 (CXCR3), CXCR2, CXCL9, chemokine ligand 7 (CCL7), CXCL11, CCL1, CXCL13, CCL12, and CCL22. Five representative key genes were performed on PBMC of blood samples from septic ARDS patients and healthy controls by RT-qPCR. The results showed that their expression was significantly higher than that in the healthy controls [IL-6 mRNA (2-ΔΔCt): 2.803±1.081 vs. 0.951±0.359, TNF mRNA (2-ΔΔCt): 2.376±0.799 vs. 1.150±0.504, CXCL10 mRNA (2-ΔΔCt): 2.500±0.815 vs. 1.107±0.515, CXCR3 mRNA (2-ΔΔCt): 1.655±0.628 vs. 0.720±0.388, CCL22 mRNA (2-ΔΔCt): 1.804±0.878 vs. 1.010±0.850, all P < 0.05], and the trends were consistent with the RNA-Seq results.
Conclusions: Biological processes such as chemotactic migration and degranulation of inflammatory cells, cytokine immune response, and signal pathways such as CXCL10/CXCR3 and IL-17 play important roles in the occurrence and development of sepsis-related exogenous ARDS, which would provide new ideas and targets for further study of lung injury mechanisms and clinical prevention and treatment.