APOE and keratoconus: And MMP2 expressed in CSCs was associated with ImC-derived APOE and MMP9. MMP3 was associated with ImC-derived MMP9 and CEC-derived LGALS3. Importantly, the metallopeptidase inhibitor gene TIMP2 was associated with ImC-derived APOE and POMC. These results indicated that the balance of MMPs and TIMPs, a critical determinant of ECM integrity and function in corneal stroma, was potentially regulated by communications between CSCs and ImCs/CECs during keratoconus progression.