miR-146a-5p Antagonized AGEs- and P.g-LPS-Induced ABCA1 and ABCG1 Dysregulation in Macrophages via IRAK-1 Downregulation

The miR-146-mediated IL-1 receptor-associated kinase 1 (IRAK-1) feedback circuit has been shown to inhibit inflammatory response in macrophages against lipopolysaccharide (LPS). The aim of this study is to compare the antagonized effects of miR-146a-5p on Porphyromonas gingivalis (P.g) lipolysaccharide (LPS)- and advanced glycation end products (AGEs)-triggered ABCA1 and ABCG1 dysregulation and explore the underlying mechanism. THP-1-derived macrophages transfected with miRNA mimics or not were treated with P.g LPS or AGE-BSA, respectively. The mechanism of endotoxin tolerance was mimicked. miR-146a-5p levels and protein levels of IRAK-1, LXRα/β, ABCA1, and ABCG1 were detected by stem–loop reverse transcription followed by TaqMan PCR analysis and Western blotting. Our results showed that miR-146a-5p levels were significantly increased in macrophages after 24 h of stimulation with high dose of P.g LPS or AGE-BSA. Macrophages transfected with miR-146a-5p mimics attenuated the dysregulation of ABCA1/G1 induced by P.g LPS and AGEs through IRAK-1 downregulation. In low-dose LPS-tolerized cells, elevated miR-146a-5p antagonized the increase of ABCA1, ABCG1, and IRAK-1. However, low-dose AGE-BSA did not increase miR-146a-5p levels. In conclusion, the model of endotoxin tolerance is suitable for the antagonistic effects on the dysregulation of ABCA1/G1 induced by high dose of P.g LPS. Conversely, low-dose AGEs did not induce the model of P.g LPS-mediated tolerance.