Canonical Wnt Signaling Promotes Macrophage Proliferation during Kidney Fibrosis.

Background: Wnt/β-catenin, an evolutionary conserved signaling pathway, plays an essential role in modulating kidney injury and repair. Our previous studies demonstrated that Wnt/β-catenin signaling could stimulate macrophage M2 polarization and contribute to kidney fibrosis. However, whether canonical Wnt signaling activation leads to macrophage proliferation during kidney fibrosis remains to be determined.

Methods: In this study, a mouse model with macrophage-specific β-catenin gene deletion was generated and a unilateral ureter obstruction (UUO) model was created.

Results: In a mouse model with UUO nephropathy, deletion of β-catenin in macrophages attenuated macrophage proliferation and accumulation in kidney tissue. Wnt3a, a well-known canonical Wnt signaling stimulator, could markedly promote macrophage proliferation, whereas blocking canonical Wnt signaling with ICG-001 or ablating β-catenin could largely inhibit macrophage colony-stimulating factor-stimulated macrophage proliferation. Wnt3a treatment could time-dependently upregulate cyclin D1 protein expression and blocking β-catenin signaling could downregulate it.

Conclusion: These results demonstrate that Wnt/ β-catenin signaling is essential for promoting macrophage proliferation during kidney fibrosis.