TREM1 promotes neuroinflammation after traumatic brain injury in rats: Possible involvement of ERK/cPLA2 signalling pathway

• Published in: Neuroscience Vol. 561; pp. 74 - 86
• Main Authors: Zhang, Chunyan, Jiang, Feng, Liu, Shengqing, Ni, Haibo, Feng, Zhanchun, Huang, Minye, Lu, Yunwei, Qian, Yinwei, Shao, Jianfeng, Rui, Qin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 22.11.2024
• Subjects: Microglial polarization; Neuroinflammation; TBI; TREM1; MWM; Microglial polarization; DMSO; cPLA2; Neuroinflammation; CNS; TREM1; ICH; mNSS; TUNEL; TBI; SAH; RT-qPCR; microglial polarization; neuroinflammation
• ISSN: 0306-4522; 1873-7544; 1873-7544
• DOI: 10.1016/j.neuroscience.2024.09.036

[Display omitted] •TBI induced increased expression of TREM1 in microglia.•TREM1 inhibitor LP17 could alleviate neuroinflammation after TBI.•LP17 could reduce neuronal apoptosis and ameliorate nerve dysfunction after TBI.•Inhibtion TREM1 by LP17 could block the ERK/cPLA2 signalling pathway after TBI. The neuroinflammatory response promotes secondary brain injury after traumatic brain injury (TBI). Triggering receptor expressed on myeloid cells 1 (TREM1) is a key regulator of inflammation. However, the role of TREM1 in TBI is poorly studied. The purpose of this study was to investigate the role of TREM1 in TBI and the possible underlying mechanism. We found that the protein expression of TREM1 significantly increased after TBI in rats, and the TREM1 protein localized to microglia. Inhibition of the TREM1 protein with LP17 significantly blocked ERK phosphorylation and reduced cytoplasmic phospholipase A2 (cPLA2) protein expression and phosphorylation. In addition, LP17-mediated TREM1 inhibition significantly reduced the protein expression of iNOS and increased the protein expression of Arg1. Moreover, after TREM1 was inhibited, the secretion of the proinflammatory factors TNF-α and IL-1β was significantly reduced, while the secretion of the anti-inflammatory factors IL-4 and IL-10 was significantly increased. Additionally, inhibition of TREM1 by LP17 significantly reduced neuronal apoptosis and ameliorated nerve dysfunction in TBI model rats. In conclusion, our findings suggest that TREM1 enhances neuroinflammation and promotes neuronal apoptosis after TBI, and these effects may be partly mediated via the ERK/cPLA2 signalling pathway.