Background: TREM2 expressed on microglia plays an important role in modulating inflammation in neurodegenerative diseases. It remains unknown whether TREM2 modulates hyperglycemia-induced microglial inflammation. Methods: We investigated the molecular function of TREM2 in high glucose-induced microglial inflammation using western blotting, qPCR, ELISA, pulldown, and co-IP methods. Results: Our data showed that in high glucose-induced BV2 cells, TREM2 was increased, and the proinflammatory cytokine IL-1β was increased. TREM2 knockout (KO) attenuated the proinflammatory cytokine IL-1β; conversely, TREM2 overexpression (OE) exacerbated IL-1β expression. Furthermore, we found that high glucose promoted the interaction of TREM2 with NLRP3. TREM2 KO abolished the interaction of TREM2 with NLRP3, while TREM2 OE enhanced the interaction. Moreover, TREM2 KO reduced high glucose-induced NLRP3 inflammasome activation, and TREM2 OE augmented high glucose-induced NLRP3 inflammasome activation, indicating that high glucose enhances the expression of TREM2, which activates the NLRP3 inflammasome. To further clarify whether the NLRP3 signaling pathway mediates the TREM2-regulated inflammatory response, we blocked the NLRP3 inflammasome by knocking out NLRP3 and treating cells with a caspase1 inhibitor, which decreased the levels of the IL-1β proinflammatory cytokine but did not affect the high glucose-induced expression of TREM2. Conclusions: TREM2 modulates high glucose-induced microglial inflammation via the NLRP3 signaling pathway.

Golgi stress has been observed in various neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. Whether Golgi stress participates in hyperglycemia-induced neuroinflammation, and how it is regulated remain unclear. First, we found that high glucose (HG) could induce dispersed Golgi apparatus (GA) in BV2 cells, which can be reversed by knockout of NLRP3. Next, we discovered that HG could promote the interaction of NLRP3 and VPS35 and then enhances the interaction of VPS35 and Golph3; knockout of NLRP3 suppressed the expression of VPS35 and Golph3; knockout of VPS35 reduced the expression of Golph3 but not NLRP3, indicating that HG induced the activation of NLRP3/VPS35/Golph3 pathway in BV2 cells. Further, we elucidated the signaling pathway that Golph3 mediated GA stress in HG condition. We used GST-pulldown and Co-IP experiments methods to show that HG promoted the interaction of Golph3 and Vimentin, knockout of Golph3 alleviated the expression of Vimentin. Knockout out of Golph3 and Vimentin both ameliorated HG induced dispersed Golgi apparatus. Collectively, our study demonstrated that HG regulates GA stress through NLRP3/VPS35/Golph3/Vimentin pathway. At last, we found that a combination of small molecular inhibitors targeting NLRP3 and Golph3 selected by molecular docking could alleviate HG-induced neuroinflammation in vitro and in vivo. Therefore, the molecular inhibitors targeting NLRP3 and Golph3 have great potential for use in the development of anti-diabetes neuroinflammatory therapies.