CTSB and metabolic dysfunction-associated steatohepatitis: CTSB knockout NASH mice (FPC-fed mice) demonstrated higher expression of the anti-inflammatory phenotype macrophage “M2” marker Arg1 and decreased expression of the proinflammatory phenotype macrophage “M1” markers iNOS and F4/80 compared to NASH mice with normal CTSB expression, suggesting that in NASH mice, cathepsins induce proinflammatory M1 macrophages [54].