Transcriptomic profiling of Csf3r^hiCD14^hi neutrophils in lung tissue of mice before and after irradiation

To investigate the transcription of neutrophils (Neu) expressing high levels of Csf3r^hiCD14^hiNeu in C3H/HeN mouse lung tissues before and after irradiation.

Twelve C3H/HeN mice were randomly divided into an irradiation group and a control group before being exposed to a single dose of 20 Gy chest irradiation. Twenty-four weeks after irradiation, two Neu subsets, Csf3r^hiCD14^hiNeu and Csf3r^lowCD14^hiNeu, were selected from lung tissues of irradiated and non-irradiated mice by flow cytometry. Transcriptomic sequencing (RNA-Seq) was performed on the two types of cells. Differentially expressed genes (DEGs) were identified using the DESeq2 package. Functional enrichment analysis and gene set enrichment analysis (GSEA) were performed using the gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases.

At 24 weeks post-irradiation, the alveolar space was significantly reduced, collagen deposition increased, and fibrosis localized in C3H/HeN mice. RNA-seq analysis suggested that there were 1499 DEGs in Csf3r^hiCD14^hiNeu compared with Csf3r^lowCD14^hiNeu in the irradiated group, 179 of which were upregulated and 1320 downregulated. In the control group, there were 701 significantly upregulated and 431 downregulated genes in Csf3r^hiCD14^hiNeu compared with Csf3r^lowCD14^hiNeu. Compared with non-irradiated Csf3r^lowCD14^hiNeu, there were 1319 upregulated and 219 downregulated genes in the irradiated group. Compared with non-irradiated Csf3r^hiCD14^hiNeu, the irradiated group had 202 upregulated and 540 downregulated genes. GO enrichment analysis indicated that these DEGs were involved in immune response, Wnt signaling pathway, and cytokine production. KEGG pathway analysis pointed to significant enrichment in the TGF-β signaling pathway, cytokine-cytokine receptor interactions, and Jak-STAT signaling pathway. GSEA revealed significant alterations in non-canonical NF-κB signaling, PD-1 signaling, and laminin interaction-related pathways.

Thoracic γ-ray irradiation can cause pulmonary fibrosis in C3H/HeN mice, with marked transcriptomic differences between Csf3r^hiCD14^hi and Csf3r^lowCD14^hiNeu subsets in lung tissue post-irradiation.