Intracellular calcium affects neutrophil chemoattractant expression by macrophages in rats with cerulein-induced pancreatitis

Abstract

Pancreatitis complicated with infection often results in the development of multiple organ failure. We investigated the role of altered intracellular calcium as a priming signal for cytokine-induced neutrophil chemoattractant expression in this process. Agents modulating cytosolic Ca2+ were utilized to study the in vivo and in vitro cytokine-induced neutrophil chemoattractant expression for macrophages in rats with cerulein-induced pancreatitis after intraperitoneal administration of lipopolysaccharide as a septic challenge. Pretreatment with the calcium channel blocker verapamil significantly reduced serum cytokine-induced neutrophil chemoattractant concentrations in rats with cerulein-induced pancreatitis after septic challenge. Lipopolysaccharide-stimulated in vitro cytokine-induced neutrophil chemoattractant (CINC) production by peritoneal macrophages was significantly enhanced by pretreatment with thapsigargin (an inhibitor of the endoplasmic reticulum-resident Ca2+-ATPase), but not by A23187 (a calcium-specific ionophore, extracellular Ca2+ influx). Pretreatment with U73122 (a phospholipase C inhibitor) inhibited lipopolysaccharide-stimulated but not basal cytokine-induced neutrophil chemoattractant production, while verapamil (a calcium channel blocker), TMB-8 (an inhibitor of calcium release from endoplasmic reticulum), and W7 (calmodulin antagonist) completely abrogated the chemoattractant production. Altered intracellular calcium, due to Ca2+ efflux from intracellular stores, may be involved in the "priming" of macrophages to release cytokine-induced neutrophil chemoattractant following triggering with lipopolysaccharide during acute cerulein pancreatitis.