Fibrotic remodeling in the NOD/ShiLtJ mouse model of Sjögren's disease: insights from single-cell transcriptomics and AI-driven ECM quantification.

Sjögren's Disease (SjD) is an autoimmune disorder characterized by salivary gland hypofunction and lymphocytic infiltration, yet the contribution of fibrosis to glandular dysfunction remains unclear. We evaluated the NOD/ShiLtJ mouse as a model for salivary gland fibrosis and used it to examine the impact of antifibrotic therapy on extracellular matrix (ECM) remodeling. To assess therapeutic potential, we treated NOD/ShiLtJ female mice with nintedanib, an FDA-approved antifibrotic agent used to treat chronic fibrosing interstitial lung disease. Fibrosis was assessed using single-cell RNA sequencing combined with Picrosirius red staining and AI-assisted digital pathology quantification of collagen I patterning with FibroNest. Single-cell RNA sequencing revealed that fibroblast populations in the submandibular and sublingual salivary glands of the female NOD/ShiLtJ mouse exhibited increased levels of ECM genes, including Col1a1, Col1a2, and Col3a1, relative to control mice. Consistent with these transcriptional changes, Picrosirius Red staining, combined with AI-assisted fibrosis quantification of collagen I patterns, demonstrated significant fibrotic remodeling in the periacinar ECM in submandibular glands of female NOD/ShiLtJ mice relative to controls. Notably, fibrosis severity strongly correlated with the diabetic phenotype characteristic of this strain, and both periductal and periacinar fibrosis progressed with age. An 8-week nintedanib treatment resulted in modest but measurable reductions across multiple fibrotic indices. Collectively, these findings establish the NOD/ShiLtJ strain as a model of SjD-associated salivary gland fibrosis and provide proof-of-concept evidence supporting antifibrotic strategies as a potential therapeutic avenue for salivary gland dysfunction in SjD.