BACKGROUND: In response to traumatic injury or infection, human neutrophils are directed to the site of injury or infection by CXC chemokines that signal via 2 receptors, CXCR-1 and CXCR-2. In vitro studies have shown preferential loss of CXCR-2 expression and function after exposure to interleukin 8, N-formyl-methionyl-leucyl-phenylalanine (fMLP), C5a, and tumor necrosis factor alpha. HYPOTHESIS: CXCR-2 expression and function are preferentially down-regulated in severely injured patients. METHODS: We studied 20 patients within 24 hours of admission to the hospital. Patients with head injuries were excluded. Injury Severity Scores (range, 1-50; mean, 35) were calculated for each patient. To determine expression of CXCR-1 and CXCR-2, flow cytometry was used. Intracellular calcium mobilization and neutrophil migration to 10 nmol of interleukin 8, growth-related oncogene alpha, and fMLP was measured to determine receptor function. RESULTS: Compared with CXCR-1, there is a greater loss of CXCR-2 receptor expression in the severely injured group (P = .01). Neutrophils from patients with Injury Severity Scores greater than 16 did not mobilize calcium in response to growth-related oncogene alpha. However, there was no loss of calcium mobilization to interleukin 8 or fMLP. Chemotaxis to various stimulants is decreased in all injury groups. CONCLUSIONS: CXCR-2 expression and function are preferentially down-regulated in severely injured patients. Our data suggest that there are multiple mechanisms, in addition to receptor down-regulation, that play a role in the loss of migration and calcium flux in human neutrophils after injury.
BACKGROUND: In response to traumatic injury or infection, human neutrophils are directed to the site of injury or infection by CXC chemokines that signal via 2 receptors, CXCR-1 and CXCR-2. In vitro studies have shown preferential loss of CXCR-2 expression and function after exposure to interleukin 8, N-formyl-methionyl-leucyl-phenylalanine (fMLP), C5a, and tumor necrosis factor alpha. HYPOTHESIS: CXCR-2 expression and function are preferentially down-regulated in severely injured patients. METHODS: We studied 20 patients within 24 hours of admission to the hospital. Patients with head injuries were excluded. Injury Severity Scores (range, 1-50; mean, 35) were calculated for each patient. To determine expression of CXCR-1 and CXCR-2, flow cytometry was used. Intracellular calcium mobilization and neutrophil migration to 10 nmol of interleukin 8, growth-related oncogene alpha, and fMLP was measured to determine receptor function. RESULTS: Compared with CXCR-1, there is a greater loss of CXCR-2 receptor expression in the severely injured group (P = .01). Neutrophils from patients with Injury Severity Scores greater than 16 did not mobilize calcium in response to growth-related oncogene alpha. However, there was no loss of calcium mobilization to interleukin 8 or fMLP. Chemotaxis to various stimulants is decreased in all injury groups. CONCLUSIONS:CXCR-2 expression and function are preferentially down-regulated in severely injured patients. Our data suggest that there are multiple mechanisms, in addition to receptor down-regulation, that play a role in the loss of migration and calcium flux in human neutrophils after injury.
Authors: Pieter H C Leliefeld; Catharina M Wessels; Luke P H Leenen; Leo Koenderman; Janesh Pillay Journal: Crit Care Date: 2016-03-23 Impact factor: 9.097