Monitoring Atsttrin-Mediated Inhibition of TNFα/NF-κβ Activation Through In Vivo Bioluminescence Imaging.

The NF-κβ transcription factor is a molecular mediator crucial to many biological functions and a central regulator of inflammatory and immune responses. NF-κβ is activated by multiple immunologically relevant stimuli, including members of the tumor necrosis factor (TNF) superfamily, and targeting TNF/NFκβ activity is a therapeutic objective in many inflammatory and autoimmune conditions. Here, we describe the generation of a transgenic reporter mouse model, expressing the human tumor necrosis factor α (TNF-α) transgene (TNF-tg) and carrying the luciferase gene under control of the NFκB-responsive element (NF-κB-Luc). Bioluminescence imaging shows that overexpression of TNF-α effectively activates NF-κB luciferase in vivo. To evaluate this system as a screen for potential therapeutics targeting the TNF/NFκβ signaling pathway, we treated double mutant mice with PGRN-derived Atsttrin, an engineered molecule comprising the minimal progranulin (PGRN):TNFR binding fragments previously demonstrated as therapeutic in multiple models of TNF/NFκβ-driven disease. Administration of Atsttrin could effectively inhibit luciferase activity in TNF-tg:NF-κB-Luc double mutant mice and demonstrates that this transgenic model can be used to non-invasively monitor the in vivo efficacy of modulators of TNF-activated NF-κB signaling pathway.