Cytokine-like protein 1 enhances the pro-inflammatory functions of neutrophils in septic mice / 中华急诊医学杂志

ABSTRACT

Objectives:To analyze the effect of cytokine-like protein 1 (CYTL1) on the pro-inflammatory functions of neutrophils in septic mice.Methods:C57BL/6 mice were randomly (random number)divided into the sepsis group and control group, with 6-12 mice in each group. A septic mouse model was established by the procedure of cecal ligation and puncture (CLP). Neutrophils were isolated from peripheral venous blood 8 h after the procedures according to the density gradient centrifugation method, and the neutrophils were treated with CYTL1 recombinant protein. The Boyden chemotaxis assays were used to detect the activity of CYTL1. fMLF and interleukin-8 were used as positive controls. Phagocytosis was determined by confocal microscopy or on a FACSVerse. Reactive oxygen species generation in neutrophils were monitored with the commercial CellROX Green fluorescent probe.Results:Compared with the control group, CYTL1 showed strong chemotactic activity on neutrophils of septic mice [(10.0 ± 2) vs (66.3 ± 4), t=-21.6, P <0.0001]. CYTL1 has stronger chemotactic activity than IL-8 [(66.3 ± 4.0) vs (21.7 ± 6.5), t = 10.1, P = 0.001]. But the chemotactic activity of fMLF and CYTL1 changed little on neutrophils of septic mice [(66.3 ± 4.0) vs (86.0 ± 13.5), t=-2.4, P = 0.073]. CYTL1 could augment the uptake of E.coli by neutrophils compared with the sepsis group [(7.35 ± 1.66) vs (2.84 ± 0.62), t = 4.4, P = 0.012]. The number of E.coli particles swallowed intracellular by a single cell significantly increased upon the stimulation of CYTL1. CYTL1 could also enhance the intracellular reactive oxygen species production of neutrophils of septic mice [(84340.1 ± 5353.5) vs (351018.7 ± 72291.7), t = 6.4, P = 0.003]. Conclusions:CYTL1 can prompt the pro-inflammatory functions of neutrophils in septic mice. In the early phase of bacterial infection, this protein may play an important role in regulating the inflammation.