Search

Glucocorticoids (GCs) are widely prescribed for various medical conditions, but prolonged use can result in osteonecrosis of the femoral head (ONFH), a serious condition characterized by bone tissue death due to reduced blood flow. Alpha-2-macroglobulin (A2M) is known to regulate oxidative stress and has been implicated in numerous biological processes. However, its role in GCs-induced ONFH has not been fully elucidated. This study investigates the involvement of A2M in ONFH by examining its activation of the Keap1/Nrf2 signaling pathway. Transcriptomic and proteomic analyses of patient samples with GCs-induced ONFH revealed a significant downregulation of A2M. A rat model of GCs-induced ONFH was then used to overexpress A2M, with subsequent evaluation through histopathological staining. Single-cell RNA sequencing and proteomic analysis indicated that A2M overexpression promotes the proliferation of anti-inflammatory macrophage clusters. Both in vivo and in vitro experiments demonstrated that A2M overexpression significantly alleviated ONFH symptoms by modulating oxidative stress and apoptosis via the Keap1/Nrf2 pathway. These findings underscore the critical role of A2M in mitigating GCs-induced ONFH, providing new therapeutic strategies and targets for future research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Our study investigated the possible molecular mechanism of glucocorticoid in steroid-induced osteonecrosis of the femoral head (SINFH) through regulating serum alpha-2-macroglobulin and SIRT2-mediated BMP2 deacetylation. Essential genes involved in glucocorticoid-induced SINFH were screened by transcriptome sequencing and analyzed by bioinformatics, followed by identifying downstream regulatory targets. Rat bone marrow mesenchymal stem cells were isolated and treated with methylprednisolone (MP) for in vitro cell experiments. Besides, a glucocorticoid-induced rat ONFH was established using the treatment of MP and LPS. ChIP-PCR detected the enrichment of SIRT2 in the promoter region of BMP2, and the deacetylation modification of SIRT2 on BMP2 was determined. Bioinformatics analysis revealed that glucocorticoids may induce ONFH through the SIRT2/BMP2 axis. In vitro cell experiments showed that glucocorticoids up-regulated SIRT2 expression in BMSCs by inducing oxidative stress, thereby promoting cell apoptosis. The up-regulation of SIRT2 expression may be due to the decreased ability of α2 macroglobulin to inhibit oxidative stress, and the addition of NOX protein inhibitor DPI could significantly inhibit SIRT2 expression. SIRT2 could promote histone deacetylation of the BMP2 promoter and inhibit its expression. In vitro cell experiments further indicated that knocking down SIRT2 could protect BMSC from oxidative stress and cell apoptosis induced by glucocorticoids by promoting BMP2 expression. In addition, animal experiments conducted also demonstrated that the knockdown of SIRT2 could improve glucocorticoid-induced ONFH through up-regulating BMP2 expression. Glucocorticoids could induce oxidative stress by down-regulating serum α2M to promote SIRT2-mediated BMP2 deacetylation, leading to ONFH., Competing Interests: Declaration of competing interest The author declares no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)