AUTHOR=Sun Zhongyi , Hu Yanan , Qu Jiachen , Zhao Qiuyue , Gao Han , Peng Zhiyong 

TITLE=Identification of apoptosis-immune-related gene signature and construction of diagnostic model for sepsis based on single-cell sequencing and bulk transcriptome analysis

JOURNAL=Frontiers in Genetics

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2024.1389630

DOI=10.3389/fgene.2024.1389630

ISSN=1664-8021

ABSTRACT=<sec><title>Introduction</title><p>Sepsis leads to multi-organ dysfunction due to disorders of the host response to infections, which makes diagnosis and prognosis challenging. Apoptosis, a classic programmed cell death, contributes to the pathogenesis of various diseases. However, there is much uncertainty about its mechanism in sepsis.</p></sec><sec><title>Methods</title><p>Three sepsis gene expression profiles (GSE65682, GSE13904, and GSE26378) were downloaded from the Gene Expression Omnibus database. Apoptosis-related genes were obtained from the Kyoto Encyclopedia of Genes and Genomes Pathway database. We utilized LASSO regression and SVM-RFE algorithms to identify characteristic genes associated with sepsis. CIBERSORT and single cell sequencing analysis were employed to explore the potential relationship between hub genes and immune cell infiltration. The diagnostic capability of hub genes was validated across multiple external datasets. Subsequently, the animal sepsis model was established to assess the expression levels of hub genes in distinct target organs through RT-qPCR and Immunohistochemistry analysis.</p></sec><sec><title>Results</title><p>We identified 11 apoptosis-related genes as characteristic diagnostic markers for sepsis: <italic>CASP8</italic>, <italic>VDAC2</italic>, <italic>CHMP1A</italic>, <italic>CHMP5</italic>, <italic>FASLG</italic>, <italic>IFNAR1</italic>, <italic>JAK1</italic>, <italic>JAK3</italic>, <italic>STAT4</italic>, <italic>IRF9</italic>, and <italic>BCL2</italic>. Subsequently, a prognostic model was constructed using LASSO regression with <italic>BCL2</italic>, <italic>FASLG</italic>, <italic>IRF9</italic> and <italic>JAK3</italic> identified as hub genes. Apoptosis-related genes were closely associated with the immune response during the sepsis process. Furthermore, in the validation datasets, aside from <italic>IRF9</italic>, other hub genes demonstrated similar expression patterns and diagnostic abilities as observed in GSE65682 dataset. In the mouse model, the expression differences of hub genes between sepsis and control group revealed the potential impacts on sepsis-induced organ injury.</p></sec><sec><title>Conclusion</title><p>The current findings indicated the participant of apoptosis in sepsis, and apoptosis-related differentially expressed genes could be used for diagnosis biomarkers. <italic>BCL2</italic>, <italic>FASLG</italic>, <italic>IRF9</italic> and <italic>JAK3</italic> might be key regulatory genes affecting apoptosis in sepsis. Our findings provided a novel aspect for further exploration of the pathological mechanisms in sepsis.</p></sec>