Neural Regeneration Research ›› 2023, Vol. 18 ›› Issue (2): 434-438.doi: 10.4103/1673-5374.346468

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The Alzheimer’s disease-associated gene TREML2 modulates inflammation by regulating microglia polarization and NLRP3 inflammasome activation

Si-Yu Wang1, #, Xin-Xin Fu2, #, Rui Duan1, Bin Wei1, Hai-Ming Cao1, Yan E1, Shuai-Yu Chen1, Ying-Dong Zhang1, 2, *, Teng Jiang1, *   

  1. 1Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China; 2Department of Clinical Pharmacy, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu Province, China
  • Online:2023-02-15 Published:2022-08-09
  • Contact: Teng Jiang, MD, PhD, jiang_teng@njmu.edu.cn; Ying-Dong Zhang, MD, PhD, zhangyingdong@njmu.edu.cn.
  • Supported by:
    This work was supported by the National Natural Science Foundation of China, No. 81974156 (to TJ) and the Natural Science Foundation of Jiangsu Province, No. BK20201117 (to YDZ).

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Abstract: Triggering receptor expressed on myeloid cells-like 2 (TREML2) is a newly identified susceptibility gene for Alzheimer’s disease (AD). It encodes a microglial inflammation-associated receptor. To date, the potential role of microglial TREML2 in neuroinflammation in the context of AD remains unclear. In this study, APP/PS1 mice were used to investigate the dynamic changes of TREML2 levels in brain during AD progression. In addition, lipopolysaccharide (LPS)  stimulation of primary microglia as well as a lentivirus-mediated TREML2 overexpression and knockdown were employed to explore the role of TREML2 in neuroinflammation in the context of AD. Our results show that TREML2 levels gradually increased in the brains of APP/PS1 mice during disease progression. LPS stimulation of primary microglia led to the release of inflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor-α in the culture medium. The LPS-induced microglial release of inflammatory cytokines was enhanced by TREML2 overexpression and was attenuated by TREML2 knockdown. LPS increased the levels of microglial M1-type polarization marker inducible nitric oxide synthase. This effect was enhanced by TREML2 overexpression and ameliorated by TREML2 knockdown. Furthermore, the levels of microglial M2-type polarization markers CD206 and ARG1 in the primary microglia were reduced by TREML2 overexpression and elevated by TREML2 knockdown. LPS stimulation increased the levels of NLRP3 in primary microglia. The LPS-induced increase in NLRP3 was further elevated by TREML2 overexpression and alleviated by TREML2 knockdown. In summary, this study provides the first evidence that TREML2 modulates inflammation by regulating microglial polarization and NLRP3 inflammasome activation. These findings reveal the mechanisms by which TREML2 regulates microglial inflammation and suggest that TREML2 inhibition may represent a novel therapeutic strategy for AD. 

Key words: Alzheimer’s disease, APP/PS1 mice, inflammatory cytokine, lipopolysaccharide, microglia, neuroinflammation, NLRP3 inflammasome, polarization, susceptibility gene, TREML2