KLF2 Inhibits Ferroptosis and Improves Mitochondrial Dysfunction in Chondrocyte Through SIRT1/GPX4 Signaling to Improve Osteoarthritis

Osteoarthritis (OA), a disease of articular joints, is the leading cause of disability in the elderly. Repressing ferroptosis and improving mitochondrial function can delay the progression of OA. Kruppel-like factor 2 (KLF2) exerts a protective effect on OA. However, whether KLF2 affects ferroptosis and mitochondrial function during OA remains unknown. The OA in vivo and in vitro models were constructed in this work. The structural damage of knee joint in OA mice was evaluated through Micro-CT scanning. H&E, SOFG, TB, and TUNEL staining were applied for pathological examination of cartilage tissues. ELISA was employed to examine the contents of inflammatory factors. Additionally, iron deposition in cartilage tissues was measured by Prussian blue staining, and the levels of proteins related to ferroptosis were assessed by immunoblotting. Besides, mitochondrial morphology and function were estimated using a transmission electron microscope and JC-1 staining. In interleukin (IL)-1β-treated C28/I2 cells, the levels of inflammatory factors, intracellular ROS, mitochondrial ROS, lipid ROS, and Fe²⁺ were measured. Mitochondrial function was evaluated by detecting the levels of mitochondrial membrane potential (MMP), ATP, mPTP, and OCR. KLF2 overexpression ameliorated the structural damage of knee cartilage in OA mice. KLF2 upregulation inhibited ferroptosis and alleviated mitochondrial damage in knee cartilage of OA mice and IL-1β-treated C28/I2 cells. Moreover, KLF2 overexpression activated SIRT1/GPX4 signaling in vivo and in vitro. EX527 addition blocked the influences of KLF2 upregulation on ferroptosis and mitochondrial dysfunction in IL-1β-treated C28/I2 cells. Altogether KLF2 inhibits ferroptosis and improves mitochondrial dysfunction in chondrocytes through SIRT1/GPX4 signaling to improve OA.