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Inhibition of S100A8/A9 Ameliorates Neuroinflammation by Blocking NET Formation Following Traumatic Brain Injury

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Journal Redox Biol
Date 2025 Feb 10
PMID 39929053
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Abstract

Traumatic brain injury (TBI) triggers a robust inflammatory response that is closely linked to worsened clinical outcomes. S100A8/A9, also known as calprotectin or myeloid-related protein-8/14 (MRP8/14), is an alarmin primarily secreted by activated neutrophils with potent pro-inflammatory property. In this study, we explored the roles of S100A8/A9 in modulating neuroinflammation and influencing TBI outcomes, delving into the underlying mechanisms. S100A8/A9-enriched neutrophils were present in the injured brain tissue of TBI patients, and elevated plasma levels of S100A8/A9 were correlated with poorer neurological function. Furthermore, using a TBI mouse model, we demonstrated that treatment with the selective S100A8/A9 inhibitor Paquinimod significantly mitigated neuroinflammation and neuronal death, thereby improving the prognosis of TBI mice. Mechanistically, we found that S100A8/A9, in conjunction with neutrophil activation and infiltration into the brain, enhances reactive oxygen species (ROS) production within neutrophils, accelerating PAD4-mediated neutrophil extracellular trap (NET) formation, which in turn exacerbates neuroinflammation. These findings suggest that S100A8/A9 amplifies neuroinflammatory responses by promoting NET formation in neutrophils. Inhibition of S100A8/A9 effectively attenuated NET-mediated neuroinflammation; however, when PAD4 was overexpressed in the brain using adenovirus, leading to an increased formation of NET in the brain, the anti-inflammatory effects of S100A8/A9 inhibition were markedly diminished. Further experiments with PAD4 knockout mice confirmed that the reduction of NETs could substantially alleviate S100A8/A9-driven neuroinflammation. Finally, we established that the suppression of NET formation by S100A8/A9 inhibition is primarily mediated through the AMPK/Nrf2/HO-1 signaling pathway. These findings underscore the critical pathological role of S100A8/A9 in TBI and emphasize the need for further exploration of S100A8/A9 inhibitor Paquinimod as a potential therapeutic strategy for TBI.

References
1.
Morganti-Kossmann M, Semple B, Hellewell S, Bye N, Ziebell J . The complexity of neuroinflammation consequent to traumatic brain injury: from research evidence to potential treatments. Acta Neuropathol. 2018; 137(5):731-755. DOI: 10.1007/s00401-018-1944-6. View

2.
Liao X, Xie R, Zheng S, Fan C, Zuo M, Chen S . Bioinformatics and molecular docking reveal Cryptotanshinone as the active anti-inflammation component of Qu-Shi-Xie-Zhuo decoction by inhibiting S100A8/A9-NLRP3-IL-1β signaling. Phytomedicine. 2024; 136():156257. DOI: 10.1016/j.phymed.2024.156257. View

3.
Zhai Y, Ye S, Wang Q, Xiong R, Fu S, Du H . Overexpressed ski efficiently promotes neurorestoration, increases neuronal regeneration, and reduces astrogliosis after traumatic brain injury. Gene Ther. 2022; 30(1-2):75-87. DOI: 10.1038/s41434-022-00320-x. View

4.
Papayannopoulos V . Neutrophil extracellular traps in immunity and disease. Nat Rev Immunol. 2017; 18(2):134-147. DOI: 10.1038/nri.2017.105. View

5.
Yan L, Bjork P, Butuc R, Gawdzik J, Earley J, Kim G . Beneficial effects of quinoline-3-carboxamide (ABR-215757) on atherosclerotic plaque morphology in S100A12 transgenic ApoE null mice. Atherosclerosis. 2013; 228(1):69-79. PMC: 3640742. DOI: 10.1016/j.atherosclerosis.2013.02.023. View