TLR4 and intervertebral disk degenerative disorder: In intervertebral disc degeneration (IDD) model, by inhibiting the TLR4 pathway and activating the PI3K/AKT signaling pathway, H-sEVs miR-17-5p enhanced the proliferation of human nucleus pulposus cells (HNPCs) and promoted ECM synthesis, contributing to the alleviation of IDD by facilitating the proliferation and synthesis of the HNPCs’ matrix (Zhou et al., 2022).