Research Paper Volume 15, Issue 10 pp 4288—4303

DNMT1 regulates polarization of macrophage-induced intervertebral disc degeneration by modulating SIRT6 expression and promoting pyroptosis in vivo

Yang Hou1, , Jiangang Shi1, , Yongfei Guo1, , Guodong Shi1, &, ,

  • 1 Department of Orthopaedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
& This corresponding author has a verified history of publications using a personal email address for correspondence.

Received: February 22, 2023       Accepted: April 24, 2023       Published: May 17, 2023
How to Cite

Copyright: © 2023 Hou et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Background: Intervertebral disc degeneration (IDD) is a complex phenomenon and a multifactorial degenerative disease that creates a heavy economic burden on health systems globally. Currently, there is no specific treatment proven to be effective in reversing and delaying the progression of IDD.

Method: This study consisted of animal and cell culture experiments. The role of DNA methyltransferase 1 (DNMT1) on regulating the M1/M2 macrophages polarization and pyroptosis, as well as its effect on Sirtuin 6 (SIRT6) expression in an IDD rat model and in tert-butyl hydroperoxide (TBHP)-treated nucleus pulposus cells (NPCs) were explored. Rat models were constructed, followed by transfection with lentiviral vector to inhibit DNMT1 or overexpress SIRT6. The NPCs were treated with THP-1-cells conditioned medium, and their pyroptosis, apoptosis, and viability were evaluated. Western blot, histological and immunohistochemistry staining, ELISA, PCR, and flow cytometry were all used to evaluate the role of DNMT1/ SIRT6 on macrophage polarization.

Results: Silencing DNMT1 inhibited apoptosis, the expression of related inflammatory mediators (e.g., iNOS) and inflammatory cytokines (e.g., IL6 and TNF-α). Moreover, silencing DNMT1 significantly inhibited the expression of pyroptosis markers IL- 1β, IL-6, and IL-18 and decreased the NLRP3, ASC, and caspase-1 expression. On the other hand, M2 macrophage specific markers CD163, Arg-1, and MR were overexpressed upon silencing DNMT1 or SIRT6 overexpression. At the same time, silencing DNMT1 exerted a regulatory effect on increasing the SIRT6 expression.

Conclusions: DNMT1 may be a promising potential target for IDD treatment due to its ability to ameliorate the progression of the disease.


IDD: Intervertebral disc degeneration; TBHP: Tert-butyl hydroperoxide; NPCs: Nucleus pulposus cells; DNMT1: DNA methyltransferase 1; SD: Sprague-Dawley; PBS: Phosphate-buffered saline; H&E: Hematoxylin and eosin; BSA: Bovine serum albumin; THP-1: Human monocyte cell line; PMA: Phorbol 12-myristate 13-acetate; CCK-8: Cell Counting kit-8; TUNEL: Terminal deoxynucleotidyl transferase dUTP nick-end labeling; Co-IP: Co-immunoprecipitation; PVDF: Polyvinylidene difluoride; ELISA: Enzyme-linked immunosorbent assay; BER: Base excision repair.