The activation of mTOR is required for monocyte pro-inflammatory response in patients with coronary artery disease

Nuclear factor-kappa B (NF-kappa B) is a key regulator of systematic inflammation in atherosclerosis (AS). The mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, has emerged as an important regulator of chronic inflammation. However, the relationship between mTOR and NF-kappa B remains poorly defined. The aim of the present study was to investigate the role of mTOR in the pro-inflammatory pathway of human monocytes (HMCs) in patients with coronary artery disease (CAD) and to determine the interaction between mTOR and NF-kappa B signalling in the inflammatory state. HMCs were isolated from fasting blood samples of 68 patients with CAD and 59 subjects without CAD (non-CAD) to test the activity of NF-kappa B, p65 nuclear translocation and mTOR phosphorylation, which were all significantly elevated in the CAD group compared with those in the non-CAD group. The concentrations of serum interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha were higher in the CAD group than in the non-CAD group. In an in vitro experiment, HMCs isolated from non-CAD subjects were used as culture model and were treated with sera extracted from CAD patients (CAD sera) or non-CAD subjects (con sera). CAD sera induced time-dependent phosphorylation of mTOR, aberrant NF-kappa B activation, as well as up-regulation of inflammatory factors. Moreover, inhibition of mTOR by pharmacological or genetic means abolished the CAD sera-triggered NF-kappa B activation and pro-inflammatory response. Furthermore, lipid-lowering drug statins partly blocked the CAD sera-activated mTOR and pro-inflammatory response. Our results show that CAD patients are in the pro-inflammatory state with increased NF-kappa B binding activity and enhanced mTOR phosphorylation. We also found that the activation of mTOR is required for the pro-inflammatory response via NF-kappa B-dependent pathway in HMCs, which unveils the underlying mechanism of AS and potential strategies to attenuate AS in clinical practice.