YKL-40 Knockdown Decreases Oxidative Stress Damage in Ovarian Granulosa Cells

Oxidative stress has been implicated in the pathogenesis of polycystic ovarian syndrome (PCOS). To develop novel antioxidant drugs, it is necessary to explore the key regulatory molecules involved in oxidative stress in PCOS. Plasma YKL-40 levels are elevated in patients with PCOS; however, its role remains unclear. The follicular fluids of 20 women with PCOS and 12 control subjects with normal ovarian function were collected, and YKL-40 in follicular fluids was measured by enzyme-linked immunosorbent assay. A letrozole-induced PCOS rat model was established and the expression level of YKL-40 in the ovaries was detected by immunohistochemistry. KGN cells were treated with H₂O₂ to generate an ovarian granulosa cell (OGC) model of oxidative stress. The siRNA was transfected into the cells for knockdown. The effect of YKL-40 knockdown on H₂O₂-treated KGN cells was evaluated by measuring proliferation, apoptosis, activities of T-SOD, GSH-Px, and CAT, levels of MDA, IL-1β, IL-6, IL-8, and TNF-α, and the PI3K/AKT/NF-κB signaling pathway. YKL-40 levels were elevated in the follicular fluids of women with PCOS compared with control subjects with normal ovarian function. The expression level of YKL-40 in the ovaries of rats with PCOS is obviously higher than that in the ovaries of the control group rats. H₂O₂ treatment enhanced YKL-40 mRNA expression and protein secretion. YKL-40 knockdown enhanced cell proliferation and antioxidant capacity while decreasing apoptosis and inflammatory factor levels in KGN cells following H₂O₂ treatment. The knockdown activated the PI3K/AKT signaling pathway and suppressed NF-κB nuclear translocation from the cytoplasm. YKL-40 levels were elevated in the follicular fluids of women with PCOS and the ovaries of rats with PCOS. YKL-40 expression can be induced by oxidative stress, and YKL-40 knockdown can decrease oxidative stress damage in OGCs.