Tigecycline has no effect on cytokine release in an ex vivo endotoxin model of human whole blood

In previous studies, tetracyclines have been shown to decrease the release of cytokines in experimental settings of endotoxaemia. Tigecycline is the first member of the closely related glycylglycines and, due to its broad antimicrobial spectrum, it is considered useful in the treatment of sepsis. We therefore tested its ability to influence the concentrations of the proinflammatory cytokines interleukin (IL)-1β, tumour necrosis factor-alpha (TNFα) and IL-6 in an established ex vivo model of human endotoxaemia. Whole blood from ten healthy volunteers was incubated with either saline (negative control), tigecycline (1 μg/mL [therapeutic concentration] or 100 μg/mL [supratherapeutic concentration]), lipopolysaccharide (LPS; 50 pg/mL, control) or a combination of tigecycline plus LPS (test group). Concentrations of IL-1β, TNFα and IL-6 in the supernatant were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kits. As expected, incubation with LPS significantly increased the cytokine concentrations in whole blood compared with baseline (P < 0.05). The combination of tigecycline plus LPS did not exert any significant effect on the concentrations of IL-1β, IL-6 and TNFα after 2 h and 4 h of incubation compared with LPS alone. These results indicate that proinflammatory cytokines remained unaffected by tigecycline in an established ex vivo model of systemic inflammatory response.