Single-cell RNA-seq reveals changes in cell subsets in the intraperitoneal lavage fluid during severe heat stroke mice
Authors: Li Li , Fu Jiahui , Liu Jiazhuo , Li Qin , Zou Zhimin , Lu Yin , Su Lei , Gu Zhengtao 
Published: April 2024

Background: Prolonged exposure to high temperatures and high humidity can cause a number of harmful stress reactions, including severe heat stroke and multiple organ dysfunction syndrome (MODS), which constitute a direct threat to people's lives. The pathophysiological response to severe heat stroke is more likely to be due to systemic inflammatory response syndrome (SIRS) secondary to heat injury. Consequently, in order to find more effective preventative and therapeutic strategies, it is worthwhile to begin with a research of the mechanism of severe heat stroke. Applying single-cell RNA sequencing (scRNA-seq) technology to further understand the biological functions of various cell types in severe heat stroke will facilitate the intervention of severe heat stroke.
Methods: In this experiment, mice severe heat stroke model were constructed and peritoneal lavage fluid was collected. Single-cell RNA sequencing (scRNA-seq) was used, combined with cluster analysis, Uniform Manifold Approximation and Projection (UMAP) visualization, and other bioinformatics methods to distinguish cell subgroups while using gene set variation analysis (GSVA), gene ontology (GO) function enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment to reveal the biological function of each cell subgroup.
Results: This study identified 17-cell clusters with cell type-specific gene expression patterns and cell subpopulations in the intraperitoneal lavage fluid, and these 17-cell clusters were divided into 5 major cell lineages: T-NK cells (clusters 6,7,11,17), myeloid cells (clusters 1,5,8,10,12,14), B cells (clusters 2,3,4,9,15), mast cells (clusters 13), erythroid cells (clusters 16). Simultaneously, the data demonstrated that, in comparison to other cell lineages, the rise in myeloid cells was the most notable; The subpopulation of myeloid cells is primarily composed of two cell types and twelve cell clusters: macrophages and dendritic cells (DC). The macrophages comprise clusters 1, 2, 3, 5, 6, 7, 9, 10, and the DCs include clusters 8, 11, and 12. Meanwhile given the presence of a majority of macrophages in the myeloid cells subpopulation, the number of cells in each cell cluster of of macrophages was analyzed , and it was found that the number of cells in clusters 1,3,8,10 significantly decreased, while the number of cluster 2,4,5,6 cells significantly increased after severe heat stroke. Additionally, the top 20 differentially expressed genes (DEGs) in recruited and resident macrophages were screened, and the top 20 DEGs with substantial changes were subjected to KEGG and GO analyses. Furthermore, cluster7 was a newly emerging a cell subpopulation after severe heat stroke, then GO and KEGG analyses were then conducted on the top 200 DEGs that showed significant alterations. These findings suggest that distinct cell subpopulations are impacted by biological processes and signaling pathways.
Conclusions: ScRNA-seq analysis of the intraperitoneal lavage fluid from mice suffering from severe heat stroke demonstrated the diversity of cell differentiation and the distinct characteristics of cell subpopulations, offering new insights into the pathogenic mechanism and the development of potential treatments for severe heat stroke.