Role of the mTOR Signalling Pathway in Human Sepsis-Induced Myocardial Dysfunction

Background: Sepsis-induced myocardial dysfunction (SIMD) is a life-threatening complication of sepsis. Mammalian target of rapamycin (mTOR) signalling pathway is significantly associated with SIMD in an animal model; however, there have been no clinical studies of the association in humans. Methods: We enrolled 88 patients with sepsis who were admitted to the intensive care unit (ICU) between April 2017, and April 2018. Biochemical indexes, hemodynamic parameters, and bedside echo-cardiographic parameters were recorded. Serum levels of mTOR, phosphorylated ribosome S6 protein kinase (PS6K), microtubule-associated protein light chain 3 type II (LC3B), Bcl-2-interacting mediator of cell death (BIM), interleukin 6, interleukin 10, and interferon-gamma were examined. Results: Compared with non-SIMD patients, patients with SIMD had higher ICU and 28-day mortality, PS6K and BIM levels, but lower LC3B levels. Serum PS6K levels in patients with SIMD were significantly negatively and positively correlated with LC3B and BIM, respectively. Multivariate regression analysis revealed that PS6K concentration at admission was an independent predictor of 28-day mortality. Receiver operating characteristic curve analysis indicated that a PS6K concentration cutoff of 42.43 pg/mL at ICU admission could predict the incidence of SIMD with a sensitivity and specificity of 91.7% and 96.2%, whereas a cutoff concentration of 41.17 pg/mL PS6K could predict 28-day mortality with a sensitivity and specificity of 83.3% and 54.3%, respectively. Conclusions: Patients with sepsis and SIMD had higher ICU and 28-day mortality. Higher serum PS6K concentrations were significantly associated with SIMD incidence and 28-day mortality, suggesting that activation of the mTOR pathway may play a major role in SIMD.