Wnt/β -catenin signalling shapes macrophage behaviour during injury and repair in the mouse submandibular gland

Xerostomia, the subjective sensation of dry mouth, is a debilitating consequence of head and neck radiotherapy and autoimmune disorders such as Sjögren’s syndrome. It severely impairs oral health and quality of life by promoting mucosal ulceration, infection, malnutrition, and speech difficulties, yet effective regenerative treatments remain limited. Macrophages have recently emerged as critical regulators of salivary gland repair through their roles in coordinating inflammation, fibrosis, and epithelial regeneration; however, the molecular mechanisms governing macrophage activation and function in the injured salivary gland remain poorly defined. The Wnt/β-catenin signalling pathway is a key regulator of inflammation and tissue homeostasis across multiple organs, but its role in salivary gland macrophages has not been well characterised. Here, we investigated canonical Wnt/β-catenin signalling following murine submandibular gland injury induced by main excretory duct ligation, with deligation used in selected experiments to model repair. Using Axin2CreERT2/+;R26mTmG/+ reporter mice, we observed an increase in Axin2⁺ cells and substantial recruitment of F4/80⁺ macrophages exhibiting active Wnt/β-catenin signalling within the injured, ligated gland. qPCR-based gene expression analysis revealed increased expression of Axin2, F4/80, and several Wnt genes, including Wnt2 and Wnt2b, at days 3 and 6 post-injury, and identified Wnt2 and Wnt2b as macrophage-secreted ligands. Notably, despite the injury-associated increase in Wnt/β-catenin signalling, Axin2⁺ cells did not give rise to acinar cells following deligation. Finally, conditional depletion of Wntless (Wls) using pCAGCreERT2/+;Wlsfl/fl. and Axin2CreERT2/+;Wlsfl/fl mice increased the number of CD206⁺ macrophages and reduced fibrosis, indicating a potential association between Wnt signalling, macrophage polarisation, and fibrotic repair. Together, these findings identify Wnt/β-catenin signalling as a regulator of macrophage phenotype and tissue repair in the injured salivary gland, suggesting that targeted modulation of Wnt activity may promote regeneration and enhance functional recovery.