Effects of Granulocyte Colony-Stimulating Factor on Opsonin Receptor Expression and Neutrophil Antibacterial Activity in a Mouse Model of Severe Acute Pancreatitis

Abstract

The antimicrobial function of neutrophils, which is dependent on opsonin receptors, deteriorates in severe acute pancreatitis (SAP). Granulocyte colony-stimulating factor (G-CSF) putatively enhanced levels of the opsonin receptors CD11b and CD32/16 in healthy human subjects, and provided protection against infection in animal models of SAP. A statistically convincing study of the effect of G-CSF on CD32/16 expression in an SAP model is lacking. We used a mouse model of SAP to investigate the association between G-CSF administration and CD32/16 levels on neutrophils and bacterial translocation. G-CSF or saline was subcutaneously injected into SAP-induced mice. The pancreases were histologically examined, and leukocytes were stained to count neutrophils. The expression of CD11b and CD32/16 on neutrophils was measured by flow cytometry, and bacterial translocation was observed by bacterial culture.The numbers of CD11b and CD32/16-positive neutrophils were significantly elevated in the SAP mice treated with G-CSF, and the mean fluorescence intensities of these receptors on neutrophils were significantly elevated. Bacterial translocations to cavity organs were suppressed from 17% to 6% by G-CSF treatment. Our results indicated that the number of neutrophils significantly increased with increasing expression of CD11b and CD32/16 and their mean fluorescence intensities (MFIs). This inhibited bacterial translocation to other organs. These results are in accord with other studies in SAP dogs and SAP mice. Our findings suggest that G-CSF was effective in protecting against bacterial infection in SAP mice.