Timosaponin AIII attenuates inflammatory injury in AGEs-induced osteoblast and alloxan-induced diabetic osteoporosis zebrafish by modulating the RAGE/MAPK signaling pathways

Nani Wang; Pingcui Xu; Xuping Wang; Weixuan Yao; Binjie Wang; Yuanzhao Wu; Dan Shou

doi:10.1016/j.phymed.2020.153247

Timosaponin AIII attenuates inflammatory injury in AGEs-induced osteoblast and alloxan-induced diabetic osteoporosis zebrafish by modulating the RAGE/MAPK signaling pathways

Phytomedicine. 2020 May 24:75:153247. doi: 10.1016/j.phymed.2020.153247. Online ahead of print.

Authors

Nani Wang¹, Pingcui Xu², Xuping Wang², Weixuan Yao³, Binjie Wang³, Yuanzhao Wu³, Dan Shou⁴

Affiliations

¹ Department of Medicine, Zhejiang Academy of Traditional Chinese Medicine, Hangzhou, Zhejiang, 310007, China.. Electronic address: wnn8511@163.com.
² Department of Medicine, Zhejiang Academy of Traditional Chinese Medicine, Hangzhou, Zhejiang, 310007, China.
³ The Department of Criminal Science and Technology, Zhejiang Police College, Hangzhou 310053, China.
⁴ Department of Medicine, Zhejiang Academy of Traditional Chinese Medicine, Hangzhou, Zhejiang, 310007, China.. Electronic address: shoudanok@163.com.

PMID: 32502823
DOI: 10.1016/j.phymed.2020.153247

Abstract

Background: Advanced glycation end products (AGEs) deposition causes inflammatory injury in osteoblasts and contributes to diabetic osteoporosis. The receptor for advanced glycation end product/mitogen-activated protein kinase pathway (RAGE/MAPK) signaling pathway is closely linked to the pathogenesis of diabetic osteoporosis. Timosaponin AIII, a steroidal saponin isolated from Anemarrhena asphodeloides Bunge (Asparagaceae), shows anti-inflammatory and anti-osteoporosis effects.

Purpose: The present study was aimed to investigate the therapeutic effects of timosaponin AIII on diabetic osteoporosis and whether its effect is dependent on protecting osteoblasts against AGEs-induced injury via RAGE/MAPK signaling suppression.

Methods: An alloxan-induced diabetic osteoporosis zebrafish model was applied to investigate the effects of timosaponin AIII in vivo, and alendronate was used as a positive control. Moreover, related mechanisms were explored in primary rat osteoblasts. Molecular docking was applied to investigate the interactions between timosaponin AIII and RAGE.

Results: Timosaponin AIII treatment reversed alloxan-induced reduction in the mineralized area of the larvae head skeleton, accompanied by a decreased level of triglyceride and total cholesterol in the zebrafish. Additionally, AGEs significantly influenced RAGE expression, alkaline phosphatase activity, interleukin 1β expression, interleukin 6 expression, and tumor necrosis factor-α expression, and increased cell apoptosis. Timosaponin AIII significantly downregulated AGEs-induced interleukin 1β, interleukin 6, and tumor necrosis factor-α levels, and upregulated alkaline phosphatase and osteocalcin levels. Timosaponin AIII also significantly reduced the expression of RAGE and had additive effects on downstream P38, extracellular signal-regulated kinase and c-Jun N-terminal kinase in AGEs-induced osteoblast. Molecular docking predicted that hydrogen and hydrophobic interactions occurred between timosaponin AIII and RAGE.

Conclusion: These data clarified that timosaponin AIII attenuates diabetic osteoporosis via a novel mechanism involved suppressing the RAGE/MAPK signaling pathway. Our finding highlights the potential value of timosaponin AIII as an anti-diabetic osteoporosis agent.

Keywords: RAGE; Timosaponin AIII; diabetic osteoporosis; osteoblast.