Inhibition of OLR1 reduces SASP of nucleus pulposus cells by targeting autophagy-GATA4 axis

Targeting cellular senescence and Senescence Associated Secretory Phenotype (SASP) through autophagy has emerged as a promising intervertebral disc (IVD) degeneration (IDD) treatment strategy in recent years. This study aimed to clarify the role and mechanism of autophagy in preventing IVD SASP. Methods involved in vitro experiments with nucleus pulposus (NP) tissues from normal and IDD patients, as well as an in vivo IDD animal model. GATA4's regulatory role in SASP was validated both in vitro and in vivo, while autophagy modulators were employed to assess their impact on GATA4 and SASP. Transcriptomic sequencing identified Oxidized low-density lipoprotein receptor 1 (OLR1) as a key regulator of autophagy and GATA4. A series of experiments manipulated OLR1 expression to investigate associated effects. Results demonstrated significantly increased senescent NP cells (NPCs) and compromised autophagy in IDD patients and animal models, with SASP closely linked to IDD progression. The aged disc milieu impeded autophagic GATA4 degradation, leading to elevated SASP expression in senescent NPCs. Restoring autophagy reversed senescence by degrading GATA4, hence disrupting the SASP cascade. Moreover, OLR1 was identified for its regulation of autophagy and GATA4 in senescent NPCs. Silencing OLR1 enhanced autophagic activity, suppressing GATA4-induced senescence and SASP expression in senescent NPCs. In conclusion, OLR1 was found to control autophagy-GATA4 and SASP, with targeted OLR1 inhibition holding promise in alleviating GATA4-induced senescence and SASP expression while delaying extracellular matrix degradation, offering a novel therapeutic approach for IDD management.