Establishment and characterization of mouse lymph node fibrosis models

Abstract Background Lymph node (LN) fibrosis occurs in a variety of pathological conditions, including HIV infection, obesity, cancer, and tissue injury. Fibroblastic reticular cells (FRCs) play a critical role in maintaining LN architecture and immune homeostasis, whereas their dysregulation promotes extracellular matrix (ECM) deposition and immune dysfunction. Transforming growth factor‐β1 (TGF‐β1) is a key profibrotic cytokine. However, reliable and convenient animal models for investigating LN fibrosis remain limited. Methods This study comprehensively compared four induction methods: footpad injection of TGF‐β1, lymphatic vessel ligation, inguinal subcutaneous injection of TGF‐β1, and direct intra‐LN injection of TGF‐β1. Histological analysis, transcriptomic profiling, flow cytometric analysis, and safety evaluation were performed to assess fibrosis and immune alterations. Results Among the four approaches, inguinal subcutaneous and intra‐LN injection of TGF‐β1 successfully induced LN fibrosis without causing significant injury to major organs. Notably, the intra‐LN injection model induced fibrosis in both cortical and medullary regions of LNs. Comparing the transcriptomic data of fibrotic and non‐fibrotic LNs demonstrated marked changes in fibrosis‐related genes, including pro‐fibrogenic mediators, collagens and basement membrane‐related genes, and TGF‐β1‐associated signaling pathways. In two fibrotic models, we also noticed increased macrophage infiltration and a drop in CD8 + T cells, suggesting an immune suppressive microenvironment. Furthermore, inhibition of collagen cross‐linking partially alleviated fibrotic remodeling in fibrotic LNs. Conclusion We established and characterized two mouse models of LN fibrosis induced by TGF‐β1 administration. These models provide valuable tools for investigating the mechanisms of LN fibrosis and its impact on local immune regulation, and may facilitate the development of therapeutic strategies targeting fibrotic LNs.