Dynamics of Immune Cell Infiltration and Fibroblast-Derived IL-33/ST2 Axis Induction in a Mouse Model of...

Lymphedema is an intractable disease most commonly associated with lymph node dissection for cancer treatment and can lead to a decreased quality of life. Type 2 T helper (Th2) lymphocytes have been shown to be important in the progression of lymphedema. The activation of IL-33 and its receptor, the suppression of tumorigenicity 2 (ST2) signaling pathway, induces the differentiation of Th2 cells, but its involvement in lymphedema remains unclear. In the present study, we analyzed the dynamics of immune cell infiltration, including the IL-33/ST2 axis, in a mouse tail lymphedema model. Neutrophil infiltration was first detected in the lymphedema tissue on postoperative day (POD) 2. Macrophage infiltration increased from POD 2 to 5. The number of CD4⁺ T cells, including 50% Tregs, gradually increased from POD 14. The mRNA expression of ll13 and Ifng increased on POD 21. The expression of IL-33 was induced in fibroblast nuclei within dermal and subcutaneous tissues from POD 2, and the expression of the Il1rl1 gene encoding ST2 increased from POD 7. We demonstrated the infiltration process from innate to acquired immune cells through the development of a mouse tail lymphedema. The IL-33/ST2 axis was found to be induced during the transition from innate to acquired immunity.