Abstract
Oxidative stress mediated apoptotic and pyroptotic cell death contributes to intervertebral disc (IVD) degeneration, and platelet-rich plasma (PRP) exerts protective effects to attenuate IVD degeneration. Hence, the present study aimed to validate this issue and uncover the potential underlying mechanisms. The mice and cellular models for IVD degeneration were established by using puncture method and H2O2 exposure, respectively, and we evidenced that NLRP3-mediated cell pyroptosis, apoptosis and inflammatory responses occurred during IVD degeneration progression in vitro and in vivo. Then, the PRP-derived exosomes (PRP-exo) were isolated and purified, and we noticed that both PRP-exo and ROS scavenger (NAC) reversed the detrimental effects of H2O2 treatment on the nucleus pulposus (NP) cells. Further results supported that PRP-exo exerted its protective effects on H2O2 treated NP cells by modulating the Keap1-Nrf2 pathway. Mechanistically, PRP-exo downregulated Keap1, resulting in the release of Nrf2 from the Keap1-Nrf2 complex, which further translocated from cytoplasm to nucleus to achieve its anti-oxidant biological functions, and H2O2 treated NP cells with Nrf2-deficiency did not respond to PRP-exo treatment. In addition, miR-141-3p was enriched in PRP-exo, and miR-141-3p targeted the 3' untranslated region (3'UTR) of Keap1 mRNA for its degradation, leading to Nrf2 translocation. Furthermore, overexpression of miR-141-3p ameliorated the cytotoxic effects of H2O2 on NP cells, which were abrogated by upregulating Keap1 and silencing Nrf2. Taken together, we concluded that PRP secreted exosomal miR-141-3p to activate the Keap1-Nrf2 pathway, which helped to slow down IVD degeneration.