OA29 Epigenetic regulation of IL-4 promoter targeting p300 attenuating intervertebral disc degeneration and pain by inhibiting IL-1β

Abstract Background/Aims Low back pain (LBP) is a prevalent condition primarily caused by intervertebral disc degeneration (IVDD), which imposes a substantial social and medical burden. Effective targeted treatments to prevent the progression of IVDD and alleviate LBP are still lacking. p300, a critical member of the histone acetyltransferase (HAT) family, is involved in the regulation of inflammation. This study aims to investigate the role of p300/IL-4 in IVDD and pain and elucidate the underlying molecular mechanism. Methods Human intervertebral disc samples were collected and graded based on the Pfirrmann grading scheme. A rat model of IVDD was established through posterior disc puncture, and various treatments were administered. Human nucleus pulposus cells (NPCs) were isolated and cultured, followed by assessments including qRT-PCR, Western blotting, immunofluorescence, and histopathological analyses. The mechanical and thermal hyperalgesia were assessed using von Frey hair tests and the plantar test, respectively. Chromatin immunoprecipitation (ChIP) and ChIP-qPCR were performed, and lentivirus transduction was used for p300 knockdown. Results We investigated the role of CREB binding protein (CBP)/p300 in IVDD. Degenerated nucleus pulposus (NP) tissues from IVDD patients exhibited a significant downregulation of p300 at both nucleic acid and protein levels, while CBP levels remained unchanged. Manipulating p300 expression in NPCs regulated matrix production, with p300 overexpression enhancing aggrecan and collagen II expression and knockdown leading to increased matrix-degrading proteins. In a rat IVDD model, activating p300 function with CTPB (p300-specific activator) alleviated IVDD and pain, while inhibiting p300 with C646 exacerbated IVDD and pain. Transcriptome analysis implicated IL-4 as a downstream effector of p300, and IL-4 demonstrated protective effects against IVDD and pain. Mechanistically, p300 was found to acetylate H3K27 at the IL-4 promoter, promoting its expression. Conclusion The novel findings of this study suggest that the p300/IL-4/IL-1β axis may represent a promising therapeutic target for IVDD and LBP. These results propose a hypothesis that, early in the inflammatory phase, NPCs may initiate a self-protective mechanism through p300, aiding itself in preserving a favourable metabolic microenvironment. This mechanism is primarily mediated by the expression of IL-4, which has the capacity to counteract IL-1β, rather than TNF-α. Disclosure H. Cui: None. Z. Zheng: None.