Rapamycin‐nanoliposomes target the mTORC1‐mediated autophagy–lysosomal and NLRP3/Caspase‐1 pathways to inhibit nucleus pulposus cell senescence in intervertebral discs

Abstract

Abstract Nucleus pulposus (NP) cell quiescence maintains intervertebral disc homeostasis, while mTORC1 regulates autophagy–lysosomal function and inflammatory secretion to preserve quiescence—rapamycin specifically targets mTORC1. Herein, we fabricated rapamycin‐nanoliposomes (rapa‐lipos) via ultrasonic dispersion, thin‐film dispersion, and filtration to improve rapamycin bioavailability, investigating their role in inhibiting the senescence phenotype of NP cells through β‐gal staining, lysosomal staining, transmission electron microscopy, ELISA, and cell cycle inhibitors. The mechanistic effects of rapa‐lipos on mTORC1, NLRP3/Caspase‐1 pathway (NCP) and autophagy–lysosomal pathway (ALP) were also analyzed by western blotting, immunofluorescence (IF), Si‐RNA (raptor), and PCR. In vivo, rapa‐lipos were injected into rat intervertebral disc with IL‐1β‐induced degeneration, assessed via HE staining, x‐ray, MRI, and IF. Rapa‐lipos exhibited high encapsulation efficiency, favorable drug loading, uniform particle size, and controlled release, suppressing NP cell senescence‐related phenotypes (morphological changes, elevated IL‐1β/TNF‐α secretion, increased β‐gal activity, lysosomal dysfunction, upregulated P21/P16 and reduced P27 expression). Mechanistically, rapa‐lipos targeted‐inhibited mTORC1, then blocked NCP and activated ALP to maintain NP cell quiescence. In vivo, x‐ray, MRI and histological evaluation confirmed rapa‐lipos mitigated intervertebral disc degeneration. Collectively, rapa‐lipos target mTORC1‐mediated NCP and ALP to inhibit NP cell senescence, offering a promising strategy for intervertebral disc degeneration prevention.