The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization

Oxygen radical production in neutrophils interacting with platelets and surface-immobilized plasma proteins: Role of tyrosine phosphorylation

The interaction between neutrophil granulocytes and platelets is considered to play an important role in the inflammatory process induced by an implanted foreign material. However, the cellular mechanisms involved remain incompletely understood. We used a luminol-dependent chemiluminescence (CL) technique to analyze the generation of reactive oxygen species (ROS) in human neutrophils interacting with different plasma protein-coated surfaces in the presence or absence of unstimulated or stimulated platelets. The role of tyrosine phosphorylation in the regulation of NADPH oxidase activity was evaluated with quantitative fluorescence microscopy and the specific tyrosine kinase inhibitor genistein. We found that the ROS-production is 2 to 3 times higher in neutrophils on immunoglobulin G (IgG)-coated surfaces than in cells interacting with albumin- or fibrinogen-coated surfaces. Incubation with superoxide dismutase and catalase revealed that about 45% of the ROS was released extracellularly on IgG surfaces whereas corresponding values were 90% and 85% in neutrophils interacting with albumin and fibrinogen, respectively. The presence of platelets markedly increased the extracellular generation of ROS, mainly in neutrophils interacting with IgG- or fibrinogen-coated surfaces whereas the intracellular production was only modestly affected. Quantitative fluorescence microscopy of neutrophils stained with FITC-conjugated anti-phosphotyrosine antibodies showed a correlation between tyrosine phosphorylation, cell spreading, and ROS production. Platelets markedly amplified the anti-phosphotyrosine staining on both fibrinogen- and IgG-coated surfaces whereas the low level of tyrosine phosphorylation in neutrophils on albumin-coated surfaces was not further elevated by platelets. Furthermore, the tyrosine kinase inhibitor genistein inhibited both extra- and intracellular ROS production in neutrophils regardless of the presence of platelets. We demonstrate that plasma protein coating and the presence of platelets are crucial for the inflammatory response of adhering neutrophils and that the oxidative response correlates with the extent of tyrosine phosphorylation of proteins in focal contacts.

The influence of plasma proteins and platelets on oxygen radical production and F-actin distribution in neutrophils adhering to polymer surfaces

It is well known that blood cell interactions with artificial surfaces might have deleterious effects on host tissue, however, the mechanisms involved are far from understood. In this study, neutrophil-platelet interaction on uncoated or protein-coated polymer surfaces was investigated. Cell spreading, reorganization of actin filaments and release of oxygen metabolites (measured as luminol-amplified chemiluminescence) were used as criteria for cell activation on positively charged, hydrophilic 1,2-diaminocyclohexane, and negatively charged, hydrophobic hexamethylene-disiloxane. The model surfaces were made by radio frequency plasma discharge polymerization. Neutrophil contact with the uncoated polymers induced a prolonged generation of oxygen radicals. Precoating of the polymer surfaces with human serum albumin (HSA) or fibrinogen, markedly reduced neutrophil activation, whereas coating with human immunoglobulin G (IgG), a well-known opsonin, resulted in significantly higher levels of cell activation. Consequently, protein coating overruled the activating effects of the polymer surfaces. The presence of unstimulated or thrombin-stimulated platelets markedly increased the reactivity of neutrophils against fibrinogen- and IgG-coated surfaces. However, neutrophils remained relatively unreactive in the presence of platelets on HSA-treated surfaces. Comparison of the different types of surfaces used, reveals a correlation between the degree of cell spreading, reorganization of the actin cytoskeleton and the amount of oxygen radicals produced. Our results suggest that the acute inflammatory reaction on a biomaterial surface is highly dependent on the nature and composition of the first adsorbed protein layer and the extent of platelet activation.

In vivo cell recruitment, cytokine release and chemiluminescence response at gold, and thiol functionalized surfaces

Hydroxylated and methylated surfaces were prepared by the self-assembled monolayer technique (SAM) of alkane thiols on gold. The surfaces were used to evaluate the influence of implant surface chemistry on protein deposition and inflammatory cell response. Implants were inserted subcutaneously in the rat for 3 and 24 h. The surface chemical properties influenced the in vitro rat plasma protein adsorption (ellipsometry/antibody) with few exceptions (albumin not found and fibrinogen always found). The number of recruited cells and their distribution (DNA from implant versus from exudate) was influenced by the different chemistries at 24 h, but not at 3 h. HIS48+, ED1+, ED2+ and small numbers of CD5+ cells were present in the exudate at both time periods (flow cytometry). The cellular oxidative metabolism was low, although cells on -OH surfaces responded with the highest phorbol ester-stimulated chemiluminescence (CL)/DNA. The levels of cytokines IL-1alpha, IL-1beta and TNFalpha (ELISA) were not influenced by material surface chemistry. Sham operated sites had a higher cytokine concentration/DNA compared with exudates from an implant milieu. The results of this study show that surface chemical functionalization modifies specific events in the inflammatory response around implants in soft tissues.