[Bioinformatics analysis and key gene verification of sepsis myocardial macrophage microarray data based on GEO database].

Bioinformatics analysis was used to screen differentially expressed genes (DEGs) in macrophages of sepsis myocardial injury and to verify key genes. Experiment 1 (gene chip and bioinformatics analysis): The gene chip data GSE104342 of cardiac macrophages in septic mice was downloaded from Gene Expression Omnibus database. DEGs were obtained by R language analysis. DAVID online database was used to obtain gene ontology and kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of DEGs. STRING online database was used for protein-protein interaction network analysis of DEGs, and then key genes were screened by using Cytoscape software and molecular complex detection (MCODE) plug-ins. Experiment 2 (sepsis model construction and related protein verification): Ten male C57BL/6 mice, aged 8-14 weeks. Five mice were randomly selected as control group, and 5 mice were selected as the sepsis group by building a mice sepsis model . Echocardiography was used to detect the cardiac function. Hematoxylin-eosin staining was used to assess the cardiac morphology. TUNEL staining was used to evaluate cardiomyocyte apoptosis. Immunofluorescence staining was used to detect the expression of differentiation antigen cluster 206 (CD206),inducible nitric oxide synthases (iNOS),F4/80,suppressor of cytokine signaling 3 (Socs3) ,interleukin 1 receptor antagonist (Il1rn) and chemokine C-C motif ligand 7 (Ccl7) protein. RAW264.7 macrophages were cultured and divided into 2 groups: LPS groupstimulated by lipopolysaccharide (LPS, 1 mg/L) and blank control group treated with equal-volume phosphate buffer solution. Reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the expression of Socs3, Il1rn and Ccl7 . Experiment 1: 24 647 genes were screened in GSE104342 dataset and 177 genes (0.72%) were differential expression, including 120 up-regulated genes and 57 down-regulated genes. Gene ontology enrichment analysis showed that DEGs were mainly involved in inflammatory response, immune response, apoptosis regulation and antigen processing and presentation. KEGG signaling pathway analysis showed that DEGs in cardiac macrophages of septic mice were mainly enriched in cytokine-cytokine receptor interaction, tumor necrosis factor signaling pathway, NOD like receptor signaling pathway. Three hub genes were obtained by STRING and Cytoscape analysis, including Socs3, Il1rn and Ccl7. Experiment 2: In vivo, it was found that compared with the control group, the cardiac function of the sepsis mice decreased significantly, the myocardial cells were significantly edema, inflammatory cell infiltration, myocardial fiber rupture, some myocardial nuclei dissolved and disappeared, and the cardiomyocyte apoptosis increased, suggesting that the sepsis myocardial injury model of mice was successfully constructed. Compared with the control group, the expression of CD206 in the myocardium of septic mice was down-regulated, the expression of iNOS, F4/80, Socs3, Il1rn and Ccl7 were up-regulated. In addition, there was co-localization between Socs3, Il1rn, Ccl7 and F4/80 protein. Compared with the blank control group, the expression of Socs3, Il1rn and Ccl7 significantly upregulated after LPS intervention by RT-PCR. The selected key genes Socs3, Il1rn and Ccl7 were up-regulated in myocardial macrophages of septic mice. Socs3, Il1rn and Ccl7 are expected to become new targets for the diagnosis and treatment of sepsis cardiac injury.