CTSG and infection: This response is initiated by the innate immune system, where neutrophils play a pivotal role by selectively infiltrating the site of infection and releasing granules containing serine proteases, including neutrophil elastase (NE), cathepsin G (CatG), protease 3 (PR3), and neutrophil serine protease 4 (NSP4), collectively classified as neutrophil serine proteases (NSPs) [1].