An in vitro model of cell migration: evaluation of vascular endothelial cell migration.

In vivo vascular endothelial cell (VEC) migration is thought to play a central role in the development of new capillaries as well as the resurfacing of large vessels. Recently, we have developed an in vitro VEC migration assay system based on the ability of VEC to migrate off of tissue culture microcarrier beads. For these studies, bovine pulmonary artery VEC were grown to confluence on Cytodex 3 microcarrier beads (MCB). Next, the confluent VEC covered microcarrier beads were pipetted into 4-cm2 wells of a tissue culture plate and incubated at 37 degrees C/5% CO2. At various time intervals, the movement of the VEC off of the MCB onto the tissue culture surface was evaluated microscopically. Using this assay, we have studied the effect of endothelial cell growth supplement and various matrices (i.e., fibronectin, gelatin, and Matrigel) on VEC migration. These studies demonstrated that: (i) gelatin had no effect on normal or mitomycin C-pretreated VEC migration; (ii) fibronectin had no effect on normal VEC migration, but stimulated the relative migration of mitomycin pretreated VEC; and (iii) Matrigel significantly suppressed both normal and mitomycin C-pretreated VEC migration. Endothelial cell growth supplement (ECGS) stimulated both normal and mitomycin C-pretreated VEC migration on fibronectin at concentrations of 10 micrograms/ml ECGS. Pretreatment with ECGS had no effect of normal or mitomycin C VEC migration on gelatin. Finally, ECGS stimulated a statistically significant increase in the migration of normal and mitomycin C-pretreated VEC migration on Matrigel.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine regulation of C3 and C5 production by the human type II pneumocyte cell line, A549.

A growing body of literature suggests that a variety of cell products (e.g., cytokines, C components, etc.) likely play an important role during inflammation and host defense by locally regulating the diverse functions of recruited (i.e., immunologic cells) as well as tissue cells. Previously, a number of investigations have demonstrated the ability of immunologic cells to produce C components in vitro, and further studies have identified a variety of cytokines that can regulate C component production by these cells. Recently, we have demonstrated the ability of lung tissue cells, including epithelial cells and fibroblasts, to synthesize and secrete numerous C components and complement regulatory proteins in vitro. Additionally, we have demonstrated that C component production can be modulated by a variety of factors including endotoxin and serum. In our studies we investigated the effects of specific cytokines, i.e., IL and IFN, on the production of the third (C3) and fifth (C5) C components by the continuous cell line of human type II pneumocytes (A549). Specifically, using sensitive ELISA we demonstrated that A549 pneumocytes exposed to IL-1 alpha, IL-1 beta, or IL-2 induced a dose-dependent, more than twofold, increase in C3 production and a 50% decrease in C5 production when compared to control (untreated) A549 cells. Interestingly, IFN-alpha significantly decreased both C3 and C5 production, i.e., 38 and 71%, respectively, in a dose-dependent manner. IFN-gamma had no effect on C3 production, but significantly decreased C5 production by A549 pneumocytes by 84%. These data not only demonstrate that cytokines have the capability to modulate C3 and C5 production by human type II pneumocytes in vitro, but that C3 and C5 production by these cells can be regulated independently by different cytokines. In vivo, cytokine modulation of C component production by local tissue cells likely plays an important role in the regulation of inflammation and host defense within the lung.

Elevation of serum chemotactic factor inactivator activity in rabbits induced by inflammation and chemotactic factor.

Inflammatory mediators such as the vasoactive and chemotactic factors, which are formed during the activation of serum complement, are extremely potent biologic peptides and are thought to be under the rigid control of specific serum-derived regulators or inactivators, including the anaphylatoxin inactivator (AI) and the chemotactic factor inactivator (CFI). Our understanding of the biologic importance and implication of these regulators in inflammatory reactions is primarily based on in vitro observations, and there is only limited data on their in vivo importance. Previously, alterations in CFI and AI levels were detected in chronic inflammatory disease states, but no data on their activity or role during acute inflammatory reactions have been demonstrated. Here we demonstrate the elevation of serum CFI activity during acute inflammatory reactions in rabbits. Specifically, inflammatory reactions were induced in rabbits by intraperitoneal injections of 0.1% oyster glycogen. Rabbit serum CFI levels rose rapidly over the first 4 hours after glycogen injection, reaching levels 4-8 times higher than the preglycogen serum CFI levels. Additional studies demonstrated that acute elevations of serum CFI levels could also be induced in rabbits by intravenous infusion of activated rabbit serum or C5-derived chemotactic factors. Infusion of saline, albumin, or the synthetic chemotactic peptide f-Met-Leu-Phe did not cause elevation of the serum CFI levels in rabbits. Thus, we take these data to support our hypothesis that 1) CFI is a "hyperacute phase reactant" that is elevated during inflammatory reactions, and 2) that this elevation of serum CFI activity is probably triggered by the appearance of specific C5-derived chemotactic factors within the vasculature. These studies not only provide exciting new insights into the regulatory mechanisms involved in acute inflammatory reactions but suggest that novel approaches to antiinflammatory therapy may be forthcoming.