Potential role of IL-8, platelet-activating factor and TNF-α in the sequestration of neutrophils in the lung: effects on neutrophil deformability, adhesion receptor expression, and chemotaxis
✍ Scribed by Ellen M. Drost; William MacNee
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 159 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
The microvasculature of the normal lung contains a pool of sequestered neutrophils, which is markedly enhanced in acute lung inflammation. Lung neutrophil sequestration is determined by the cells' deformability and adhesivity to capillary endothelium, and is a prerequisite for emigration into the airspaces. We assessed the effect of several proinflammatory mediators associated with acute lung inflammation on these factors. Plateletactivating factor, IL-8 and formyl-Met-Leu-Phe (fMLP) induced a marked, but transient reduction in neutrophil deformability. Also, increased surface expression of the g 2 -integrin and CD11b, and shedding of L-selectin (CD62L) was observed for these stimuli. TNF- § in contrast caused a small decrease in cell deformability only after 30 min, and shedding of L- selectin, but no change in CD11b levels. However, TNF- § -pretreatment markedly enhanced the fMLP response for cell deformability, CD11b expression and CD62L loss. Moreover, all pre-treatments were found to induce chemokinesis, and all except fMLP, enhanced fMLPdirected chemotaxis. We were able to demonstrate, using specific TNF- § receptor antagonists, that the TNF- § -induced changes in chemotaxis were mediated through the 55-kDa receptor. Also, inhibitors of the mitogen activated protein (MAP) kinase signaling pathway showed that the p38 MAP kinase pathway was involved for fMLP-directed chemotaxis of TNF-pretreated neutrophils, although activation of the extracellular signal-regulated kinase (ERK) pathway was also seen. These data demonstrate the differential role of proinflammatory mediators in controlling neutrophil sequestration and migration, which may orchestrate the severity of the inflammatory response in such respiratory diseases as chronic obstructive pulmonary disease and asthma.