Mitochondrial Electron Transport Chain Inhibition Suppresses LPS-Induced Inflammatory Responses via TREM1/STAT3 Pathway in BV2 Microglia

Mitochondrial damage and neuroinflammation belong to two of the most important pathological factors in multiple neurological disorders. However, the effect of mitochondrial damage of microglia on microglial activation under pathological conditions has remained unclear. In our current study, we used BV2 microglia as a cellular model to determine the effects of mitochondrial electron transport chain (ETC) inhibitors on LPS-induced inflammatory responses of microglia. We found that all of the three mitochondrial ETC inhibitors, including rotenone, sodium azide and antimycin A, significantly inhibited LPS-induced inflammatory responses of the microglia, assessed by determinations of the protein or mRNA levels of IL-1{beta}, IL-6, TNF-, iNOS and COX2. Nuclear translocation of NF-{kappa}B p65 subunit does not appear to play an important role in the mitochondrial ETC inhibition-produced suppression of microglial activation. Instead, our study found that the mitochondrial ETC inhibitors significantly attenuated not only the LPS-induced increase in the TREM1 levels - an amplifier of inflammatory process, but also the LPS-induced increase in the ratio of phosphorylated STAT3 / STAT3. In summary, our study has suggested that mitochondrial ETC inhibition of microglia can lead to suppression of LPS-induced microglial activation, which may be mediated by the inhibitory effects of mitochondrial ETC inhibition on the LPS-induced increases in the level of TREM1 and the ratio of p-STAT3 / STAT3. These findings have provided valuable information for elucidating the relationships between mitochondrial damage and neuroinflammation in multiple neurological diseases.