A Bioluminescence Reporter Mouse Strain for In Vivo Imaging of <scp>IFNγ</scp> Cell Localization and Function

Interferon gamma (IFNγ) is a pivotal inflammatory mediator and immune regulator, but its in vivo spatiotemporal dynamics and functional roles in inflammation and carcinogenesis remain incompletely understood. Here, we developed a C57BL/6J- Ifng-2A-luciferase knock-in mouse strain using CRISPR/Cas9-mediated homology-directed repair, enabling real-time bioluminescence imaging (BLI) of IFNγ-expressing cells by inserting a luciferase cassette under the endogenous Ifng promoter. The validation confirmed that this model is capable of directly detecting Poly(I:C) -induced transient IFNγ, enhancing intratumoral IFNγ signals upon anti-PD-1/CTLA-4 therapy, and dynamically tracking IFNγ expression during imiquimod-induced psoriasis. This transgenic mouse model provides a powerful tool for non-invasive, longitudinal tracking of IFNγ-expressing cells, offering novel insights into IFNγ-mediated immune regulation in inflammation and cancer. It holds promise for identifying IFNγ-related therapeutic targets and predicting responses to immunotherapies.