Immune checkpoint inhibitors amplify type 2 immune mediated repair by pro-regenerative scaffolds

Extracellular matrix (ECM) scaffolds induce type 2 immunity to promote repair. Here, we show that immune cells recruited to ECM-treated murine muscle injuries and clinical soft tissue defects express immune checkpoints. Specifically, T H 2 cells and regulatory T cells (Tregs) increase LAG3 expression, while macrophages express PDL2. TCR analysis and a triple-reporter strain for interleukin (IL)-13 and Treg fate-mapping suggest that Tregs in ECM-treated wounds transition into T H 2-like exTregs that express LAG3. Immune checkpoint inhibition (ICI) significantly stimulated type 2 immunity in ECM-treated wounds, including increased T H 2 cells, Treg transition to T H 2-like exTregs, and pro-regenerative macrophages. Moreover, ICI enhanced muscle repair and reduced fibrosis in ECM-treated wounds. Collectively, these findings show Treg/T H 2 plasticity in wound healing and introduce a novel ICI application to enhance immune-mediated regeneration.