High mobility group box-1 regulates expression of EGFR, VEGF, StAR and TIMP1/2 in bovine granulosa cells through a mechanism involving TLR2/NF-κB

Innate immunity is involved in ovarian activity through aseptic inflammation and tissue repair. High-mobility group box-1 (HMGB1) is related to placental inflammation and a driver of inflammation throughout pregnancy. The aim of this study was to investigate the interaction of HMGB1 with TLR2 in bovine ovarian granulosa cells, and the effects of HMGB1 on bovine ovarian granulosa cells in vitro. The viability of granulosa cells were not affected by HMGB1 with the concentration less than 5 μg/mL. The mRNA levels of TLR2, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), the steroidogenic acute regulatory protein (StAR), tissue inhibitors of matrix (TIMP1/2) of ovarian granulosa cells were upregulated by HMGB1(P < 0.05). The protein levels of TLR2, TLR1 and phosphorylation-NF-κB (p-NF-κB) p65 in ovarian granulosa cells increased in 5 μg/mL HMGB1 group (P < 0.05), and TLR2 decreased in siRNA-2 group (P < 0.05). IL-6 of ovarian granulosa cells was increased by 1 μg/mL and 5 μg/mL HMGB1 (P < 0.05). These results implicate that HMGB1 has interaction with TLR2, TLR1 and p-NF-κB p65 in ovarian granulosa cells, which lead to nuclear translocation of NF-κB p65 and the secretion of interleukin-6 (IL-6). HMGB1 regulates the expression of EGFR, VEGF, StAR, TIMP1/2 and the secretion of IL-6 in ovarian granulosa cells of dairy cows through activating the TLR2/NF-κB signaling pathway, which may be interfere with ovarian physiological activity.