Degradomic and Transcriptomic Profiling Reveals Pleiotropic Roles of Extracellular Granzyme B in Scarring and Fibrosis.

Granzyme B (GzmB) is a serine protease traditionally recognized for its role in lymphocyte-mediated apoptosis. In specific conditions, GzmB accumulates in the extracellular milieu and retains its proteolytic activity, cleaving extracellular proteins thereby contributing to disease progression. Nevertheless, pathological roles of extracellular GzmB are still not fully understood. In the current study, a systems biology approach combining N-terminomic, transcriptomic and in vivo validation was applied to further delineate the mechanism(s) of action for extracellular GzmB. Multi-omic analysis revealed that GzmB cleaves major structural and non-structural extracellular matrix (ECM) molecules produced by primary human dermal fibroblasts (including type I collagen, type VI collagen and Tenascin-X), releasing matrikines and activating TGF-β alongside numerous pro-inflammatory pathways. Using bioinformatic analyses, we demonstrated that GzmB degradomic and transcriptomic signatures independently converge towards potential roles in scarring and fibrosis. Targets of interest derived from GzmB signatures were further validated at the protein level in human hypertrophic scars and keloids, as well as in a mouse model of thermal injury. Together, these findings establish new synergistic roles for GzmB in scarring and fibrosis, supporting its extracellular inhibition as a therapeutic strategy.