Establishment and characterization of mouse lymph node fibrosis models.

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.