ESTRO 2024 - Abstract Book

S5249 ESTRO 2024 cells to proliferate and form a layer after irradiation. Interestingly, ECs from lung mice six months after irradiation showed an inability to proliferate in contrast to cells from control mice, possibly reflecting a functional alteration caused by irradiation. Enrichment of ICs suspensions was around 60%. Flow cytometry revealed no significant difference in the number of ICs, normalized by lung weight, between irradiated and control mice. In contrast, the number of ECs decreased significantly in irradiated mice six months after irradiation compared with control mice. This suggests a loss of cells in favor of fibrosis formation. We then performed scRNA-seq on 48 samples (24 samples enriched in ECs and 24 samples enriched in ICs) from 24 mice (4 control mice and 4 mice irradiated at 7 days, 3 months and 6 months post-irradiation), allowing the analysis of an average of 10,000 cells per sample, each cell expressing around 1,800 genes. For the bioinformatics analysis, we merged scRNA-seq data from EC and IC enriched suspensions for each mouse, representing a total of around 500,000 cells. Analysis of the dataset with Seurat led to the identification of five clusters of ECs and eight clusters of ICs, and revealed changes in gene expression and molecular pathways in the different clusters in response to irradiation. To investigate the effect of irradiation on EC-IC interactions, we used ICELLNET and CellChat to quantitatively infer and analyze intercellular communication networks from the scRNA-seq dataset. The results suggest several modifications in the interactions between ECs and ICs, particularly monocytes and macrophages, in response to irradiation and highlight some interesting molecular pathways of interaction. Radiobiology - Normal tissue radiobiology

Conclusion:

We set up and used a murine model of radiation-induced lung fibrosis to study the molecular response of ECs and ICs in vivo over time by scRNA-seq. The dataset is very comprehensive, allowing in-depth analysis of gene expression, molecular pathways and cell-cell interactions of the different lung cell types. We found molecular pathways differentially expressed in ECs, but also changes in interactions with ICs after irradiation. These results will help us to better understand how ECs respond to irradiation in vivo, and how they orchestrate the recruitment of ICs after irradiation.

Keywords:

Endothelium,

Immune

response,

ScRNA-seq

References:

[1] O. Guipaud, C. Jaillet, K. Clément-Colmou, A. François, S. Supiot, and F. Milliat, “The importance of the vascular endothelial barrier in the immune-inflammatory response induced by radiotherapy,” Br. J. Radiol., vol. 91, no. 1089, p. 20170762, Sep. 2018, doi: 10.1259/bjr.20170762.

[2] J. Amersfoort, G. Eelen, and P. Carmeliet, “Immunomodulation by endothelial cells — partnering up with the immune system?,” Nat. Rev. Immunol., vol. 22, no. 9, pp. 576–588, 2022, doi: 10.1038/s41577-022-00694-4.

[3] F. Noël et al., “Dissection of intercellular communication using the transcriptome-based framework ICELLNET,” Nat. Commun., vol. 12, no. 1, Art. no. 1, Feb. 2021, doi: 10.1038/s41467-021-21244-x.

[4] S. Jin et al., “Inference and analysis of cell-cell communication using CellChat,” Nat. Commun., vol. 12, no. 1, Art. no. 1, Feb. 2021, doi: 10.1038/s41467-021-21246-9.

1056

Digital Poster

Combining ultrasound-induced blood-brain barrier opening and FLASH radiation: safety and feasibility

Jia-Ling Ruan 1 , Michael Gray 2 , Iain Tullis 1 , Eleanor Stride 2,3 , Kristoffer Petersson 1