Cyp7b1, a cytochrome P450 enzyme, hydroxylates carbons 6 and 7 of the B ring of oxysterols and steroids. This action reduces substrate biological activity and aids their conversion to excretable end products. It is involved in cholesterol metabolism, with its activity in the liver crucial for oxysterol inactivation and bile salt conversion [2].

In KO/CKO mouse models, Cyp7b1 has been found to play significant roles in multiple diseases. In osteoarthritis, adenoviral overexpression of Cyp7b1 in mouse joint tissues led to experimental osteoarthritis, while knockout or knockdown abrogated its pathogenesis, indicating its role in the CH25H-CYP7B1-RORα axis regulating osteoarthritis [1]. In the central nervous system autoimmune disease, CYP7B1 deficiency in mice significantly attenuated experimental autoimmune encephalomyelitis severity, reducing leukocyte infiltration, suppressing pathogenic CD4+ T cell proliferation, and decreasing myeloid cell activation [3]. In mesenchymal stem cells, BM-MSCs from CYP7B1 conditional knockout mice had impaired activation abilities, relating to delayed bone defect healing [4].

In conclusion, Cyp7B1 is essential for cholesterol metabolism, with its inactivation affecting multiple disease processes. Studies using KO/CKO mouse models have revealed its roles in osteoarthritis, central nervous system autoimmune diseases, and mesenchymal stem cell activation, providing potential therapeutic targets for these conditions.