Absence of trauma-induced leukocyte rolling in mice deficient in both P-selectin and intercellular adhesion molecule 1

Neutrophil activation by adhesion: mechanisms and pathophysiological implications

Neutrophil adhesion plays an essential role in the formation of an inflammatory exudate. Moreover, adhesion activates selective neutrophil functions and regulates the cell response to additional stimuli. In this review we summarize the information available on adhesion molecules involved in neutrophil adhesion to endothelial cells and extracellular matrix proteins and the experimental approaches which have been developed to block neutrophil adhesion and neutrophil mediated tissue damage. We also address the mechanisms of activation of selective neutrophil functions by adhesion molecules and, in particular the mechanisms of signal transduction by neutrophil integrins. On the basis of recent results obtained in our and other laboratories we propose a model hypothesizing mechanisms of signaling by neutrophil integrins involved in regulation of selective functions.

Critical role for beta7 integrins in formation of the gut-associated lymphoid tissue

Immune defence against pathogens entering the gut is accomplished by lymphocytes in the gut-associated lymphoid tissue (GALT), a major compartment of the immune system. The GALT, comprising Peyer's patches, lamina propria lymphocytes and intra-epithelial lymphocytes of the intestine, is populated by lymphocytes that migrate there from the vasculature. Here we report that, in mice deficient for the beta7 integrin subfamily of adhesion molecules, the formation of the GALT is severely impaired. This is probably due to a failure of beta7-/- lymphocytes to arrest and adhere to the vasculature at the site of transmigration into the GALT.

Infectious susceptibility and severe deficiency of leukocyte rolling and recruitment in E-selectin and P-selectin double mutant mice

During the initial phase of the inflammatory response, leukocytes marginate and roll along the endothelial surface, a process mediated largely by the selectins and their ligands. Mice with mutations in individual selectins show no spontaneous disease and have mild or negligible deficiencies of inflammatory responses. In contrast, we find that mice with null mutations in both endothelial selectins (P and E) develop a phenotype of leukocyte adhesion deficiency characterized by mucocutaneous infections, plasma cell proliferation, hypergammaglobulinemia, severe deficiencies of leukocyte rolling in cremaster venules with or without addition of TNF-alpha, and an absence of neutrophil emigration at 4 h in response to intraperitoneal Streptococcus pneumoniae peritonitis. These mice provide strong evidence for the functional importance of selectins in vivo.