Hagey Laboratory for Pediatric Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.
Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
Radiat Oncol. 2024 Jun 26;19(1):82. doi: 10.1186/s13014-024-02472-z.
Radiation-induced fibrosis (RIF) is an important late complication of radiation therapy, and the resulting damaging effects of RIF can significantly impact reconstructive outcomes. There is currently a paucity of effective treatment options available, likely due to the continuing knowledge gap surrounding the cellular mechanisms involved. In this study, detailed analyses of irradiated and non-irradiated human skin samples were performed incorporating histological and single-cell transcriptional analysis to identify novel features guiding development of skin fibrosis following radiation injury.
Paired irradiated and contralateral non-irradiated skin samples were obtained from six female patients undergoing post-oncologic breast reconstruction. Skin samples underwent histological evaluation, immunohistochemistry, and biomechanical testing. Single-cell RNA sequencing was performed using the 10X single cell platform. Cells were separated into clusters using Seurat in R. The SingleR classifier was applied to ascribe cell type identities to each cluster. Differentially expressed genes characteristic to each cluster were then determined using non-parametric testing.
Comparing irradiated and non-irradiated skin, epidermal atrophy, dermal thickening, and evidence of thick, disorganized collagen deposition within the extracellular matrix of irradiated skin were readily appreciated on histology. These histologic features were associated with stiffness that was higher in irradiated skin. Single-cell RNA sequencing revealed six predominant cell types. Focusing on fibroblasts/stromal lineage cells, five distinct transcriptional clusters (Clusters 0-4) were identified. Interestingly, while all clusters were noted to express Cav1, Cluster 2 was the only one to also express Cav2. Immunohistochemistry demonstrated increased expression of Cav2 in irradiated skin, whereas Cav1 was more readily identified in non-irradiated skin, suggesting Cav1 and Cav2 may act antagonistically to modulate fibrotic cellular responses.
In response to radiation therapy, specific changes to fibroblast subpopulations and enhanced Cav2 expression may contribute to fibrosis. Altogether, this study introduces a novel pathway of caveolin involvement which may contribute to fibrotic development following radiation injury.
辐射诱导纤维化（RIF）是放射治疗的一种重要的晚期并发症，RIF 的破坏性影响会显著影响重建效果。目前，有效的治疗选择非常有限，这可能是由于对涉及的细胞机制的持续知识差距。在这项研究中，对接受过放射治疗和未接受过放射治疗的人类皮肤样本进行了详细分析，结合组织学和单细胞转录组分析，以确定在放射损伤后皮肤纤维化发展的新特征。
从 6 名接受过肿瘤后乳房重建的女性患者中获得接受过放射治疗和对侧未接受过放射治疗的配对皮肤样本。对皮肤样本进行组织学评估、免疫组织化学和生物力学测试。使用 10X 单细胞平台进行单细胞 RNA 测序。在 R 中使用 Seurat 将细胞分离成簇。使用 SingleR 分类器将细胞类型身份分配给每个簇。然后使用非参数检验确定每个簇特有的差异表达基因。
比较放射治疗和未放射治疗的皮肤，在组织学上很容易观察到放射治疗皮肤的表皮萎缩、真皮增厚和细胞外基质中厚而紊乱的胶原沉积的证据。这些组织学特征与放射治疗皮肤的硬度增加有关。单细胞 RNA 测序显示了六种主要的细胞类型。聚焦于成纤维细胞/基质谱系细胞，鉴定出五个不同的转录簇（簇 0-4）。有趣的是，虽然所有簇都被发现表达 Cav1，但只有簇 2 也表达 Cav2。免疫组织化学显示放射治疗皮肤中 Cav2 的表达增加，而 Cav1 在未放射治疗皮肤中更容易识别，这表明 Cav1 和 Cav2 可能拮抗作用以调节纤维化的细胞反应。
对纤维母细胞亚群的特定改变和 Cav2 表达的增加可能是辐射治疗后纤维化的原因。总的来说，这项研究介绍了一种新的 Cavlin 参与途径，它可能有助于放射损伤后纤维化的发展。
