Single-Cell Sequencing Revealed Pivotal Genes Related to Prognosis of Myocardial Infarction Patients

Abstract

Objectives: Myocardial infarction (MI) is a common cardiovascular disease. Histopathology is a main molecular characteristic of MI, but often, differences between various cell subsets have been neglected. Under this premise, MI-related molecular biomarkers were screened using single-cell sequencing.

Methods: This work examined immune cell abundance in normal and MI samples from GSE109048 and determined differences in the activated mast cells and activated CD4 memory T cells, resting mast cells. Weighted gene coexpression network analysis (WGCNA) demonstrated that activated CD4 memory T cells were the most closely related to the turquoise module, and 10 hub genes were screened. Single-cell sequencing data (scRNA-seq) of MI were examined. We used t-distributed stochastic neighbor embedding (t-SNE) for cell clustering.

Results: We obtained 8 cell subpopulations, each of which had different marker genes. 7 out of the 10 hub genes were detected by single-cell sequencing analysis. The expression quantity and proportion of the 7 genes were different in 8 cell clusters.

Conclusion: In general, our study revealed the immune characteristics and determined 7 prognostic markers for MI at the single-cell level, providing a new understanding of the molecular characteristics and mechanism of MI.

Figure 1

Screening of modules associated with immune cells. (a) Wilcoxon's test compared the abundance of 22 types of immune cells between normal and myocardial infarction samples. (b) Average connectivity of selected β and different β values when R² reaches 0.7 for the first time. (c) Clustering dendrogram of comethylation modules from GSE109048. (d) Correlation analysis of 13 modules with resting mast cells, activated mast cells, and activated CD4 memory T cells.

Figure 2

The function of the turquoise module and the interaction of hub gene. (a) The GO analysis of genes in the turquoise module includes three aspects: molecular function, cellular component, and biological process. (b) The KEGG pathway enrichment analysis on the turquoise module genes. (c) Scatter plot of turquoise-GS-MM distribution. (d) The turquoise module gene-gene interaction network diagram. (e) The differential expression of 10 hub genes in normal and myocardial infarction samples was analyzed. (f) Pearson's correlation analysis among 10 hub genes.

Figure 3

scRNA-seq data analysis of human myocardial infarction. (a) The cell samples were divided into 8 subgroups by the t-SNE algorithm. (b) Eight cell subpopulations were annotated according to the marker. (c) The violin picture showed the expression patterns of specific genes in two kinds of smooth muscle cells. (d) The cell development trajectories of 8 subpopulations were predicted by the monocle. Each point represents a cell and is marked with pseudotime (right) and the cell state (left).

Figure 4

Expression heat maps of the first five marker genes in each cell subpopulation in different cell clusters.

Figure 5

Expression distribution of Hub gene and chemokines in 8 cell subpopulations. (a) Bubble map of 7 hub genes expressed in 8 cell subpopulations. (b) The expression level of chemokines and their receptors in each cell cluster. The dot color demonstrates the average intensity of expression, and the dot size shows the quantity of cells expressing the gene.

Figure 6

Characteristics of enrichment pathways in different cell subpopulations. (a) Enrichment activity of each cell subpopulation in the first 10 pathways. (b) Specific enrichment scores of 8 kinds of cell subpopulations on the 10 pathways with the greatest difference.