Antithrombin III, but not C1 esterase inhibitor reduces inflammatory response in lipopolysaccharide-stimulated human monocytes in an ex-vivo whole blood setting

In order to examine the immunomodulatory effects of antithrombin III (AT-III) and C1 esterase inhibitor (C1-INH) in human monocytes, we investigated the intracellular expression of interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-alpha in an ex-vivo laboratory study in a whole blood setting. Heparinized whole blood samples from 23 healthy male and female volunteers (mean age: 27 +/- 7 years) were pre-incubated with clinically relevant concentrations of AT-III (n = 11) and C1-INH (n = 12), then stimulated with 0.2 ng/mL lipopolysaccharide (LPS) for 3 h. After phenotyping CD14(+) monocytes, intracellular expression of IL-6, IL-8, and TNF-alpha was assessed using flow cytometry. In addition, 12 whole blood samples (AT-III and C1-INH, n = 6 each) were examined using hirudin for anticoagulation; all samples were processed in the same way. To exclude cytotoxicity effects, 7-amino-actinomycin D and Nonidet P40 staining were used to investigate probes. This study is the first to demonstrate the influence of C1-INH and AT-III on the monocytic inflammatory response in a whole blood setting, which mimics the optimal physiological setting. Cells treated with ATIII exhibited significant downregulation of the proportion of gated CD14(+) monocytes for IL-6 and IL-8, in a dose-dependent manner; downregulation for TNF-alpha did not reach statistical significance. There were no significant effects on mean fluorescence intensity (MFI). In contrast, C1-INH did not significantly reduce the proportion of gated CD14(+) monocytes or the MFI regarding IL-6, TNF-alpha, and IL-8. When using hirudin for anticoagulation, no difference in the anti-inflammatory properties of AT-III and C1-INH in monocytes occurs. Taken together, in contrast to TNF-alpha, IL-6 and IL-8 were significantly downregulated in monocytes in an ex-vivo setting of human whole blood when treated with AT-III. This finding implicates monocytes as an important point of action regarding the anti-inflammatory properties of AT-III in sepsis. C1-INH was unable to attenuate the monocytic response, which supports the hypothesis that other cellular components in whole blood (e.g., neutrophils) might be responsible for the known effects of C1-INH in inflammation. (C) 2014 Elsevier Ltd. All rights reserved.