Integrin Expression on Neutrophils in a Rabbit Model of Group B Streptococcal Meningitis

Products released by polymorphonuclear cells (PMNs) during an acute inflammatory response can result in diffuse tissue injury. Integrins are cell surface adhesion proteins that play a pivotal role in inflammation by allowing PMNs to adhere to the endothelium and migrate through the extracellular matrix. We examined the expression of β1 and β2 integrins on neutrophils from blood and cerebrospinal fluid (CSF) in an animal model of Group B Streptococcal meningitis. We further evaluated whether integrin expression correlates with pathophysiologic markers of central nervous system inflammation. Our data demonstrate that β1 and β2 integrin expression on circulating neutrophils does not significantly increase as a consequence of meningitis. In extravesated CSF neutrophils, a significant increase in expression of both β1 and β2 integrins is noted. Furthermore, a majority of the β1 integrins on extravesated neutrophils have undergone affinity modulation. Using regression analysis, we demonstrated that increasing β1 integrin expression correlates with decreasing CSF glucose concentration and serum/CSF glucose ratio. Regression analysis approached significance when CSF protein was compared to PMN β1 integrin expression. Polymorphonuclear leukocytes β1 integrin expression also showed a direct correlation to myeloperoxidase activity in brain tissue. β2 expression on CSF PMNs did not correlate with these markers of inflammation/sequestration. These data demonstrate integrin expression on extravesated neutrophils markedly increases during meningitis and support a role for β1 integrins on neutrophils in the pathophysiologic consequences of meningitis.