Background & Aims

Polyneuropathy (PNP) is a term to describe diseases of the peripheral nervous system (PNS), which in approximately 50 % of the cases are associated with pain. In PNP, activation of inflammatory pathways in peripheral nerves may lead to a pro-inflammatory environment that could modulate nerve degeneration and pain. Schwann cells are the glia cells that accompany nerve fibers and support them. Schwann cells can respond to endogenous and exogenous stimuli and participate in the development of the local inflammatory conditions present in patients with PNP.

In this study, we investigated in vitro responses of control and patient-derived human Schwann cells to pro- and anti-inflammatory stimuli. We aimed to elucidate the role of Schwann cells in the local inflammatory environment and their potential involvement in neuropathic pain development in patients with PNP.

Methods

PNP patients with neuropathic pain were recruited at the Department of Neurology, University Hospital of Würzburg. As part of their diagnostic work-up, sural nerve biopsies were collected and patient-derived Schwann cells (pdSC) were isolated. In parallel, commercial human Schwann cells were purchased as controls (chSC). Schwann cells were stimulated with potential pro- and anti-inflammatory stimuli, such as lipopolysaccharide (LPS) and resveratrol (RSV), and samples were collected at the defined time points: 2, 4, 8 and 12 hours. To measure the responses towards the stimuli, we analyzed selected pro- and anti-inflammatory markers through RT-qPCR, RNA sequencing, new generation ELISAs (ELLA) and Western blots. The targets included nuclear factor ? B (NF?B), p38 mitogen-activated protein kinases (p38 MAPK), signal transducer and activator of transcription 3 (STAT3), interleukin 6 (IL-6), IL-8, and chemokine CC ligand 2 (CCL2).

Results

Our data showed that stimulation of chSC with LPS caused an activation of the NF?B, p38, and STAT3 pro-inflammatory pathways (p < 0.05), leading to the upregulation and release of IL-6 and IL-8 (p < 0.0001). Treatment with RSV reduced the activation of these pathways and the cytokine release (p < 0.05). In addition, we demonstrated that pdSC released higher levels of IL-6 (p < 0.01), IL-8 (p < 0.05), and CCL2 (p < 0.01) upon stimulation with LPS, in comparison to chSC. This suggested that Schwann cell contribute to the local inflammatory environment involved in neurodegeneration and pain in patients with painful PNP. pdSC inflammatory response to stimuli could be reduced by treatment with RSV (p < 0.05).

Conclusions

This study confirms the contribution of Schwann cells to the creation of a pro-inflammatory environment upon stimulation and postulates about their potential role in the sural nerve of patients with painful PNP. In addition, we describe the anti-inflammatory properties of resveratrol and highlight its potential as a therapeutic compound against neurodegeneration and neuropathic pain.

References

•Sommer C, et al. “Inflammation in the pathophysiology of neuropathic pain.” Pain. 2018;159(3):595-602. doi:10.1097/j.pain.0000000000001122
•Üçeyler, Nurcan et al. “Differential gene expression of cytokines and neurotrophic factors in nerve and skin of patients with peripheral neuropathies.” Journal of neurology vol. 262,1 (2015): 203-12. doi:10.1007/s00415-014-7556-8
•Thakur, Krishan K et al. “Therapeutic implications of toll-like receptors in peripheral neuropathic pain.” Pharmacological research vol. 115 (2017): 224-232. doi:10.1016/j.phrs.2016.11.019
•Hu, Zhongsheng et al. “CNTF-STAT3-IL-6 Axis Mediates Neuroinflammatory Cascade across Schwann Cell-Neuron-Microglia.” Cell reports vol. 31,7 (2020): 107657. doi:10.1016/j.celrep.2020.107657
•Kaewkhaw, Rossukon et al. “Integrated culture and purification of rat Schwann cells from freshly isolated adult tissue.” Nature protocols vol. 7,11 (2012): 1996-2004. doi:10.1038/nprot.2012.118

Presenting Author

Patricia García-Fernández

Poster Authors

Patricia Garcia Fernandez

MSc

University Hospital of Wurzburg

Lead Author

E-mail

Kristina Krause

Lead Author

E-mail

Christian König

PhD

Lead Author

E-mail

Andrea Ebersberger

PhD

Lead Author

E-mail

Nurcan Üçeyler

MD

Department of Neurology, University of Würzburg, Germany

Lead Author

E-mail

Claudia Prof. Dr. Sommer

University Hospital Würzburg

Lead Author

E-mail

Topics

  • Mechanisms: Biological-Molecular and Cell Biology