MPO and colitis: Levels of pro-inflammatory factors such as IL-1β, IL-6, and TNF-α were significantly decreased in serum, IL-6 and TNF-α levels were significantly decreased in colon, and the activity of MPO, an oxidative stress-related enzyme, was significantly increased in TS–FMT-treated colitis mice compared with the other three groups (Fig. 5B) (p < 0.05).