1. Integrin α8 is a useful cell surface marker of alveolar lipofibroblasts.
- Author
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Fukada A, Enomoto Y, Horiguchi R, Aoshima Y, Meguro S, Kawasaki H, Kosugi I, Fujisawa T, Enomoto N, Inui N, Suda T, and Iwashita T
- Subjects
- Animals, Mice, Pulmonary Alveoli metabolism, Pulmonary Alveoli cytology, Biomarkers metabolism, Cells, Cultured, Alveolar Epithelial Cells metabolism, Fibroblasts metabolism, Mice, Inbred C57BL, Integrin alpha Chains metabolism, Integrin alpha Chains genetics
- Abstract
Background: Recent advances in comprehensive gene analysis revealed the heterogeneity of mouse lung fibroblasts. However, direct comparisons between these subpopulations are limited due to challenges in isolating target subpopulations without gene-specific reporter mouse lines. In addition, the properties of lung lipofibroblasts remain unclear, particularly regarding the appropriate cell surface marker and the niche capacity for alveolar epithelial cell type 2 (AT2), an alveolar tissue stem cell., Methods and Results: Using cell surface markers applicable even into wild-type mouse lungs, we could classify PDGFRα
+ total lung resident fibroblasts into at least two major distinct subpopulations: integrin α8 (ITGA8)+ and SCA-1+ fibroblasts. We analyzed their characteristics, including lipid content, transcriptome profiles, and alveolar stem cell niche capacity. ITGA8+ fibroblasts showed higher positivity of intracellular lipid droplets compared to SCA-1+ fibroblasts (91.0 ± 1.5% vs. 5.0 ± 0.5% in LipidTOX staining; 91.3 ± 1.4% vs. 7.1 ± 1.7% in Oil Red O staining). The fluorescence intensity of LipidTOX in the ITGA8+ fibroblasts was highest in newborn compared to adult or aged lungs. The transcriptome profile of ITGA8+ fibroblasts in adult mouse lungs, evaluated through two independent single-cell RNA-seq datasets, consistently showed higher expression of Tcf21 and Plin2, which are canonical markers of lipofibroblasts. ITGA8+ fibroblasts were primarily located in the alveolar area, particularly in the neighborhood of AT2. Compared to SCA-1+ fibroblasts, ITGA8+ fibroblasts showed higher mRNA expression of potential AT2-supportive factors, Fgf10, Fgf7, and Wnt2, but unexpectedly, exhibited lower efficiency in alveolar organoid formation., Conclusions: ITGA8+ lung fibroblasts correspond to alveolar lipofibroblasts, but the alveolar niche capacity may be lower than SCA-1+ lung fibroblasts. Further studies are necessary for the functional distinction between lung fibroblast subpopulations., Competing Interests: Declarations. Ethics approval and consent to participate: We handled the mice in accordance with the ethics guidelines of the institute. All the experiments in this study have been approved by Hamamatsu University School of Medicine (Approved numbers: 14–365, 22 − 021, 23–066, and 2023042). Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)- Published
- 2025
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