The Role of IL-6 and TMEM100 in Lumbar Discogenic Pain and the Mechanism of the Glycine-Serine-Threonine Metabolic Axis: A Metabolomic and Molecular Biology Study

Abstract

Background

It is well established that discogenic low back pain (DLBP) is often caused by the inflammatory response during intervertebral disc degeneration (IDD). However, it remains unclear how inflammatory mediators such as Interleukin-6 (IL-6) are involved in discogenic pain caused by degeneration and intervertebral disc (IVD) metabolism. The purpose of this study is to study the relationship between IL-6 and Transmembrane protein 100 (TMEM100), and to analyze the different metabolites and metabolic pathways in various rat intervertebral discs by metabonomics.

Methods

We established a rat model of IDD-DLBP by disc punctures and PBS infusion to examine the rat pain behaviors. Intervertebral disc tissues were harvested for molecular biology experiments to explore the relationship between IL-6 and TMEM100. High-resolution mass spectrometry (HRMS) was performed for untargeted metabolomics, and nuclear magnetic resonance spectroscopy metabolomics (MRS) for differential metabolites and metabolic pathways.

Results

The results showed a significant decrease in vonFrey test, hot plate test and acetone test (P < 0.05). The expression of IL-6 and TMEM100 in DLBP model was significantly higher than that in sham control group and IDD discs without PBS infusion group (P < 0.05). There were 15 major contributing metabolites identified in the DLBP intervertebral discs through metabolomic studies, involving 6 major metabolic pathways. The main differential metabolites included nitric oxide (NO), ammonia, and lactic acid as the metabolic endpoints; and the differential metabolic pathways included the glycine-serine-threonine (Gly-Ser-Thr), which is gradually weakened with the progression of inflammation.

Conclusion

The change of TMEM100 expression mediated by il-6 is related to the Gly-Ser-Thr metabolic axis and plays an important role in the relief of discogenic pain.

Keywords:

• metabolomics
• DLBP
• IDD
• IL-6
• TMEM100
• inflammatory mediators

Data Sharing Statement

The datasets used and/or analyzed during the current study are available from the authors Zhaoyang Guo and Xiaolin Wu on reasonable request.

Acknowledgments

We thank Zuoran Fan, Youfu Zhu, Master Huifei Cui (Qingdao University Affiliated Hospital) for generously sharing their experiences.

Disclosure

The authors declare no potential conflicts of interest.

Additional information

Funding

This work was supported by Shandong Provincial Natural Science Foundation (ZR2022MH218); Youth Research Fund of Affiliated Hospital of Qingdao University in 2021 (QDFYQN202101012). The National Natural Science Foundation of China (82172478); National Key Research and Development Project (2019YFC0121404); Shandong Higher Education Young Science and Technology Support Program (2021KJ048); Innovation Fund of National Orthopedics and Sports Rehabilitation Clinical Medicine Research Center (2021-NCRC-CXJJ-ZH-02); The Young Taishan Scholars Program (tsqn201909190); Postdoctoral Science Foundation of China (2021M701813); Qingdao Postdoctoral Applied Research Project (2020).