Influence of simvastatin treatment on Toll-like receptor 4 in monocytes of peripheral blood in patients with sepsis and severe sepsis

Abstract

To investigate the influence of simvastatin treatment on Toll-like receptor 4 (TLR4) in monocytes of peripheral blood in patients with sepsis and severe sepsis and its significance. A prospective randomized controlled trial was conducted. 106 patients with sepsis and 92 patients with severe sepsis admitted to Department of Critical Care Medicine of Henan Provincial People's Hospital from August 2013 to June 2015 were enrolled. These two groups of patients were randomized into conventional treatment group and simvastatin group. All patients received treatment according to the 2012 International Sepsis Treatment Guidelines, including anti-infection drugs, nutritional support, and palliative treatment, and the patients with severe sepsis were given early goal-directed therapy (EGDT). The patients in simvastatin group received simvastatin 40 mg daily orally for at least 15 days. The peripheral blood was collected and the monocytes were isolated at 1, 5, 10, 15 days after intensive care unit (ICU) admission. TLR4 expression on the surface of TLR4/CD14(+) double positive monocytes was determined by flow cytometry, and adverse reaction was observed during treatment. TLR4 expression on the surface of monocytes showed a tendency of decreasing with prolongation of simvastatin treatment in the simvastatin group in patients with sepsis (n = 59) or severe sepsis (n = 54). However, in patients with sepsis, TLR4 level was significantly decreased from 10 days in simvastatin group as compared with that of conventional therapy group (n = 47), and it was decreased up to 15 days [mean fluorescence intensity (MFI): 21 (19, 28) vs. 27 (25, 33) at 10 days, Z = 2.198, P = 0.021; 16 (15, 21) vs. 26 (23, 34) at 15 days, Z = 4.611, P = 0.002]. In patients with severe sepsis, there was no significant difference in TLR4 level at different time points between simvastatin group and conventional treatment group (n = 38) [MFI: 55 (52, 63) vs. 56 (48, 65) at 1 day, Z = 0.313, P = 0.692; 47 (42, 56) vs. 49 (41, 58) at 5 days, Z = 0.827, P = 0.533; 40 (35, 42) vs. 42 (37, 45) at 10 days, Z = 1.012, P = 0.301; 33 (30, 38) vs. 38 (35, 41) at 15 days, Z = 0.539, P = 0.571]. No adverse reaction related with simvastatin was found during treatment in patients with sepsis or severe sepsis. Statins could significantly down-regulate the TLR4 expression on peripheral blood monocytes in septic patients, while it showed no significant influence on TLR4 expression in patients with severe sepsis. A different effect of statins on TLR4 expression and the downstream inflammation process in sepsis and severe sepsis patients might partially explain the discrepancy in previous reports about the therapeutic effect of statins therapy in sepsis and severe sepsis patients.