Surfactant protein A stimulates release of neutrophil chemotactic factors by alveolar type II pneumocytes.

Mucosal immunity is an important mechanism in the response to injury. Our hypothesis is that surfactant protein A (SP-A) is an autocrine factor that stimulates alveolar type II epithelial cell release of neutrophil chemotactic factors by binding to the SP-A receptor expressed by these cells. We examined (1) the effect of SP-A (20 μg/ml) or IL-1β (10 ng/ml) on release of neutrophil chemotactic factors by primary cultures of type II cells or alveolar macrophages, and (2) the effect of intratracheal instillation of the blocking antibody to the SP-A receptor on the response to oleic acid-induced lung injury in vivo.

Protein kinase Calpha and sphingosine 1-phosphate-dependent signaling in endothelial cell.

Protein kinase C (PKC)-mediated signal transduction pathways convert extracellular stimulation into a variety of cellular functions. However, the role of various PKC isoforms in sphingosine 1-phosphate (S1P)-stimulated endothelial cells is not well understood. PKCalpha and PKCepsilon activity are increased in endothelial cell cultures, and S1P receptor transfection studies indicate S1P(3) stimulates PKCalpha and S1P1 leads to PKCepsilon activity.

Measurements of phospholipases A2, C, and D (PLA2, PLC, and PLD). In vitro microassays, analysis of enzyme isoforms, and intact-cell assays.

In order to be properly divisible, the cell membrane has to be remodeled and intracellular membranes must be converted into a vesiculated state prior to mitosis. Phospholipases A2, C, and D (PLA2, PLC, and PLD) are involved in regulatory events of intracellular mitogen signaling pathways. We describe here three methods for comprehensively assaying those phospholipases: 1) in vitro microassays, in which a radiolabeled substrate is exogenously added to cell lysates to measure the enzyme activity(ies); 2) immunocomplex assays, in which immunoprecipitation with a specific antibody is performed in order to study the contribution of a particular isoform within a family of enzymes; and 3) intact-cell or in vivo assays, in which cells are labeled with a radioactive substrate until steady state is reached.

Neutrophil beta2-integrin upregulation is blocked by a p38 MAP kinase inhibitor.

Tumor necrosis factor-alpha is known to upregulate the expression of surface adhesion molecules on polymorphonuclear leukocytes (PMNs). The purpose of this investigation was to study possible intracellular signaling pathways responsible for the upregulation of beta2 integrins on normal human PMNs induced by TNF. We report that treatment with TNF (10 ng/ml) for 30 min resulted in a significant increase in CD18 and MAC-1 surface expression (P < 0.