Synthetic leu-enkefalin analogue prevents activation of neutrophils induced by a bacterial component

Abstract

Background: Neutrophil activation is a  mandatory stage and a  sensitive marker of systemic inflammatory response. The development of this condition is associated with subsequent multiple organ failure which is the main indication for the patients stay in the intensive care unit. The search for drugs that could prevent the development of systemic inflammatory response and reduce mortality remains an urgent task of anesthesiology/resuscitation.Aim: To study the anti-inflammatory effect of dalargin, a synthetic analogue of lei-enkephalin, on human neutrophils in vitro.Materials and methods: The study was performed on blood neutrophils isolated from 5 healthy donors. A proportion of neutrophils were activated by 10 mkM formil-Met-Leu-Pro (fMLP) and 100 ng/mL lipopolysaccharide (LPS) with subsequent assessment of their activity by fluorescent antibodies to the degranulation markers CD11b and CD66b. Thereafter intact and activated neutrophils were treated with dalargin solution at concentrations of 50 and 100 mcg/mL.Results: Dalargin at 100 mcg/mL reduced the expression of CD11b molecules on the surface of intact neutrophils by 5.5-fold (p=0.008). On the contrary, LPS at a  dose of 100  ng/mL increased the expression of the same molecules by 46% (p=0.08). The addition of dalargin at 50 mcg/mL to LPS-activated neutrophils reduced the expression of CD11b molecules (p=0.016). The addition of dalargin at 50  mcg/mL to fMLP-activated neutrophils significantly (p=0.008) reduced the expression of CD11b molecules and reversed their expression virtually to the level of the control. The addition of dalargin at 100  mcg/mL to neutrophils activated by fMLP at 10 mkM reduced the expression of CD11b on their surface to a level below the control by 23% (p=0.08).Conclusion: Dalargin at the studied concentrations has an anti-inflammatory effect on both intact and pre-activated bacterial components of neutrophils, thus inhibiting the process of activation and degranulation in a dose-dependent manner.