HMOX1 and chronic kidney disease: As shown in an in vitro study on intestinal epithelial cells, pro-inflammatory stimuli, such as LPS or IS, are able to influence antioxidant defense cell systems, such as HO-1, NAD(P)H quinone oxidoreductase 1 (NQO1), and SOD, causing a state of oxidative stress not only at the renal level but also at the systemic level and particularly in the gut, which is considered a primary source of inflammation in CKD [103].