Deciphering the age-dependent changes of pulmonary fibroblasts in mice by single-cell transcriptomics

Rundong Wu; Xiaowei Zhang; Xinyuan Zhang; Lixiang Sun; Tian Xia; Ling-Juan Zhang

doi:10.3389/fcell.2023.1287133

Deciphering the age-dependent changes of pulmonary fibroblasts in mice by single-cell transcriptomics

Front Cell Dev Biol. 2023 Nov 29:11:1287133. doi: 10.3389/fcell.2023.1287133. eCollection 2023.

Authors

Rundong Wu^#¹, Xiaowei Zhang^#¹, Xinyuan Zhang¹, Lixiang Sun¹, Tian Xia¹, Ling-Juan Zhang¹

Affiliation

¹ State Key Laboratory of Cellular Stress Biology, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China.

^# Contributed equally.

Abstract

Background and objectives: The heterogeneity of pulmonary fibroblasts, a critical aspect of both murine and human models under physiological and pathological conditions, is well-documented. Yet, consensus remains elusive on the subtypes, lineage, biological attributes, signal transduction pathways, and plasticity of these fibroblasts. This ambiguity significantly impedes our understanding of the fibrotic processes that transpire in lung tissue during aging. This study aims to elucidate the transcriptional profiles, differentiation pathways, and potential roles of fibroblasts within aging pulmonary tissue. Methods: We employed single-cell transcriptomic sequencing via the 10x Genomics platform. The downstream data were processed and analyzed using R packages, including Seurat. Trajectory and stemness of differentiation analyses were conducted using the Monocle2 and CytoTRACE R packages, respectively. Cell interactions were deciphered using the CellChat R package, and the formation of collagen and muscle fibers was identified through Masson and Van Geison staining techniques. Results: Our analysis captured a total of 22,826 cells, leading to the identification of fibroblasts and various immune cells. We observed a shift in fibroblasts from lipogenic and immune-competent to fibrotic and myofibroblast-like phenotype during the aging process. In the aged stage, fibroblasts exhibited a diminished capacity to express chemokines for immune cells. Experimental validation confirmed an increase of collagen and muscle fiber in the aged compared to young lung tissues. Furthermore, we showed that TGFβ treatment induced a fibrotic, immunodeficient and lipodystrophic transcriptional phenotype in young pulmonary fibroblasts. Conclusion: We present a comprehensive single-cell transcriptomic landscape of lung tissue from aging mice at various stages, revealing the differentiation trajectory of fibroblasts during aging. Our findings underscore the pivotal role of fibroblasts in the regulation of immune cells, and provide insights into why age increases the risk of pulmonary fibrosis.

Keywords: aging; cell interaction; lung fibrosis; myofibroblasts; pulmonary fibroblasts; single-cell transcriptomics.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work is supported by the Fundamental Research Funds for the Central Universities (20720220003) and Xiamen University fund (20720200022).