| 1. |
- Nimeri, G, et al.
(författare)
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Oxygen radical production in neutrophils interacting with platelets and surface-immobilized plasma proteins : role of tyrosine phosphorylation
- 2003
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Ingår i: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636 .- 1549-3296. ; 67A:2, s. 439-447
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Tidskriftsartikel (refereegranskat)abstract
- 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. (C) 2003 Wiley Periodicals, Inc.
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| 2. |
- Nimeri, G, et al.
(författare)
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The influence of plasma proteins and platelets on oxygen radical production and F-actin distribution in neutrophils adhering to polymer surfaces
- 2002
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Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:8, s. 1785-1795
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Wetterö, Jonas, 1972-
(författare)
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Acute inflammation on model biomaterial surfaces : studies on proteins, neutrophils and platelets
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although most biomedical devices are non-toxic, disturbed acute and chronic inflammation and the lack of integration in tissues is a concern. At the time of biomaterial insertion, protein adsorption onto material surfaces precedes cell adhesion and is believed to alter unfavorably the acute inflammatory response and the subsequent tissue healing. The wound healing may encapsulate the biomaterial in a fibrous tissue. The process depends probably on the surface physical and chemical characteristics, and the accumulation of blood plasma proteins such as fibrinogen, immunoglobulins (Ig:s) and complement. Platelets and neutrophil granulocytes, which both possess inflammatory capabilities, are the first cells to appear at a surface during contact with blood. In the present thesis, model biomaterial surfaces were prepared, and the in vitro deposition of plasma proteins and the subsequent behavior of neutrophils and platelets evaluated.Complement activation at artificial surfaces during contact with blood is generally believed to proceed via the alternative pathway, i.e. through a direct covalent binding of the factor 3 (C3) thioester to nucleophilic surface groups (e.g. -OH and -NH2). The serum protein deposition onto a hydroxylated potent complement activator surface, mercaptoglycerol on gold, was studied by a combination of null-ellipsometry and polyclonal antibodies. It was observed that deposited C3 did not withstand elution with sodium dodecyl sulfate (SDS), and the binding was unaffected by reduction with hydroxylamine. Opposite results have been reported for biological surfaces and our findings call for a revision of the current activation model at artificial surfaces where instead the classical pathway of complement may be highly relevant.The effects of immobilized and partially denatured IgG on the neutrophil respiratory burst at hydrophilic and hydrophobic model surfaces were studied by lurninol-arnplitied chemiluminescence in serum containing media. IgG supported frustrated phagocytosis and generation of extracellular reactive oxygen species (ROS) on both types of surfaces, although the kinetics were different. The response was particularly potent on IgG at hydrophobic surfaces, and the finding that the respiratory burst was only moderately quenched by the blocking of complement receptors (CR:s) or Fcγ (IgG) receptors, indicates a role for intracellular cross-talk. The IgG-triggered response depended on the presence of both C3 and C1q in serum and was inhibited by disruption of the intracellular actin dynamics. Classical complement activation may also be initiated by immobilized IgM. When the activation by spontaneously adsorbed IgG and IgM on methylated hydrophobic silicon was compared, both Ig:s deposited C3 from serum, but only the activation at IgG was C1q- and Ca2+-dependent. Depletion of C1q from serum lowered the neutrophil respiratory burst and the formation of intracellular filamentous (F) actin upon adhesion to IgG-surfaces. Hence, IgG- but not IgM-coated hydrophobic surfaces activate the classical pathway via the C1 complex.Surface-bound IgG is also a potent platelet agonist via the Fcγ receptor. Neutrophil and platdet ROS generation, aggregation, and release of adenosine triphosphate in response to spontaneously adsorbed and covalendy immobilized IgG show that platelets enhance the neutrophil respiratory burst under both stirred and non-stirred serum free conditions. Blocking of the neutrophil Fcγ receptors was not sufficient to inhibit the amplification. Platelets supported neutrophil adhesion in a contact-dependent way, and the effect was mediated by intact platelets or platelet-derived fragments/microparticles. The response was, in contrast to complement dependent activation in serum, unaffected by the disruption of the actin cytoskeleton, or by blocking of neutrophil CR3 or platelet glycoprotein IIb/IIIa, suggesting an integrin- and fibrinogen-independent mechanism. Antibodies against platelet P-selectin (CD62) and P-selectin glycoprotein ligand-1 (PSGL-1 or CD162), but not L-selectin (CD62L), inhibited partly the neutrophil-platelet interaction, especially under shear. Accordingly, we suggest that during stimulation of the cells with immobilized IgG, platdet P-selectin interacts with neutrophil PSGL-1.The majority of previous adsorption studies has dealt with blood plasma proteins. However, the concentration of released cytosolic proteins may locally reach high levels upon a tissue injury. Actin is one of the most abundant proteins in the eukaryotic cytoplasm, and may tentatively accumulate at interfaces. Actin was immobilized to gold and aminated silicon surfaces and polymerized into F-actin by adjusting the osmotic conditions. Upon incubation in human serum, the actin surfaces adsorbed serum proteins, amongst them C3 and C1q. However, the complement deposition was apparendy not a result of true or prolonged complement activation, and immobilized actin evoked only a low ROS-generation, aggregation, spreading and adhesion of neutrophils and platelets (similar to low-activating albumin-surfaces). Yet, F-actin on gold recruited platelets in a C1q-dependent manner, indicating an immunoregulatory capacity of surface-bound actin.The results in the present thesis are relevant for a better understanding of the basic mechanisms that determine the fate of artificial devices in contact with human body fluids.
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| 4. |
- Wetterö, Jonas, 1972-, et al.
(författare)
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C1q-independent activation of neutrophils by immunoglobulin M-coated surfaces
- 2001
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Ingår i: Journal of Biomedical Materials Research. - 0021-9304 .- 1097-4636. ; 57:4, s. 550-558
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil granulocytes are known to rapidly adhere and undergo frustrated phagocytosis upon contact with immunoglobulin and/or complement protein opsonized artificial surfaces. In this study, we examined the relation between serum protein deposition and human neutrophil activation on hydrophobic glass and silicon model surfaces that were coated with immunoglobulin G or M (IgG/IgM), both initiators of the classical complement pathway. Protein adsorption from normal human serum (NHS) was quantified with null-ellipsometry combined with antibody techniques. The neutrophil oxygen radical production was registered by luminol-amplified chemiluminescence (CL) and the morphology, as well as changes in the content of filamentous actin (F-actin), were documented by fluorescence microscopy. Complement factor 3 (C3) bound to both IgG- and IgM-coated surfaces, but surprisingly C1q was found only on IgG-coated surfaces. Both immunoglobulins triggered complement dependent neutrophil activation. However, CL and F-actin accumulation were found sensitive to the presence of C1q in the serum only at the IgG-coated surface. We suggest that spontaneously adsorbed IgM activates the complement system and interacts with neutrophils by C1q-independent mechanisms.
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| 5. |
- Wetterö, Jonas, 1972-, et al.
(författare)
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Complement activation on immunoglobulin G-coated hydrophobic surfaces enhances the release of oxygen radicals from neutrophils through an actin-dependent mechanism
- 2000
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Ingår i: Journal of Biomedical Materials Research. - 0021-9304 .- 1097-4636. ; 51:4, s. 742-751
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophil granulocytes are among the first cells to encounter a plasma protein-coated implant and may through frustrated phagocytosis release toxic oxidative species. We used two model surfaces, hydrophobic and hydrophilic glass, to investigate the effects of plasma immunoglobulin G (IgG)-complement interactions for neutrophil adhesion and respiratory burst. The respiratory burst was measured with luminol-amplified chemiluminescence and cell adhesion was determined by labeling neutrophils with 2′, 7′-bis-(carboxy-ethyl)-5(6)-carboxyfluorescein. We demonstrate that the IgG-triggered neutrophil adhesion and oxygen radical production is augmented in the presence of normal human serum, in particular on hydrophobic surfaces, indicating that complement factors enhance the neutrophil activation. We propose that the complement factors C3, C5a, and C1q are especially important for this amplification, but factor B is probably not. Disturbance of the actin filament dynamics with cytochalasin B or jasplakinolide blocked the neutrophil radical generation on all surfaces. However, these drugs did not affect the number of adherent neutrophils. We suggest that there is a synergistic interaction between adsorbed IgG, and the complement system, which amplifies the neutrophil acute inflammatory responses through a dynamic actin cytoskeleton on synthetic surfaces.
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| 6. |
- Wetterö, Jonas, et al.
(författare)
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Interactions between surface-bound actin and complement, platelets, and neutrophils
- 2003
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Ingår i: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636 .- 1549-3296. ; 66A:1, s. 162-175
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Tidskriftsartikel (refereegranskat)abstract
- Actin exists as globular (G) monomers or polymeric filaments (F) in the cytoplasm of eukaryotic cells, mediating cell morphologic changes and motility. Large amounts of this protein may be released out to the extracellular compartment during tissue injury, but little is known about its role in biomaterial-related inflammation. We immobilized actin to methylated glass, methylated and aminated silicon, and gold model surfaces and studied the subsequent blood serum deposition and complement activation, generation of reactive oxygen species (ROS), and adhesion and aggregation of neutrophils and platelets. Null ellipsometry showed that approximately one monolayer of G-actin can be immobilized onto the model surfaces and that actin in buffer polymerized on top of this by the addition of K+ and Mg2+ ions to form a thicker layer of firmly bound F-actin. After serum incubation, F-actin bound low amounts of anti-complement factor 1q (anti-C1q). Cell responses upon contact with actin-coated surfaces were analyzed by luminol-amplified chemiluminescence, lumi-aggregometry, and fluorescence microscopy. It was shown that surface-triggered aggregation, spreading, and generation of ROS are down-regulated and comparable to the response by adsorbed albumin. However, F-actin on gold surfaces recruited platelets in a C1q-dependent manner. We conclude that in vitro adsorbed actin is a weak complement, platelet, and neutrophil activator, but that F-actin associates with both C1q and platelets. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 162–175, 2003
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| 7. |
- Wetterö, Jonas, 1972-, et al.
(författare)
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On the binding of complement to solid artificial surfaces in vitro
- 2002
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Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:4, s. 981-991
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Tidskriftsartikel (refereegranskat)abstract
- Since the realization of a complement activation capacity by artificial surfaces upon contact with blood, a common belief has evolved that charged nucleophilic surface groups such as amine (–NH2) and hydroxyl (–OH) react with and eventually bind to the internal thioester in complement factor 3 (C3). A covalent amide or ester linkage is thereby supposed to form between C3b and the surface itself. In this report, we present complement surface binding data by null-ellipsometry for two nucleophilic surfaces (–NH2 and –OH), for surfaces with immunoglobulin G (IgG) covalently bound, and for IgG spontaneously pre-adsorbed to hydrophobic silicon. The results reveal that the plasma proteins that were deposited during complement activation became eluted by sodium dodecyl sulfate. Hence the direct covalent binding between C3 and solid nucleophilic surfaces seems to be only of moderate importance, at least during shorter serum incubations. This strongly suggests that the prevalent covalent linkage model between solid artificial surfaces and C3b is not accurate. Instead we suggest a more pronounced role for C3 associations to other adsorbed proteins and/or electrostatic and hydrophobic protein–surface interactions.
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| 8. |
- Wetterö, Jonas, 1972-, et al.
(författare)
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Platelets stimulated by IgG-coated surfaces bind and activate neutrophils through a selectin-dependent pathway
- 2003
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Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 24:9, s. 1559-1573
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Tidskriftsartikel (refereegranskat)abstract
- Blood platelets bind rapidly to foreign surfaces and interact with adsorbed proteins and neutrophil granulocytes. We demonstrate by use of luminol-amplified chemiluminescence under stirred and non-stirred conditions that platelets at IgG-coated surfaces amplify the neutrophil extracellular release of reactive oxygen species (ROS). The neutrophil response involved tyrosine phosphorylation, but was only in part induced by neutrophil Fcγ-receptor stimulation. The platelet mediated effects were contact-dependent since the respiratory burst was inhibited when the IgG-stimulated platelets were removed by filtration, but not when they were fixed in paraformaldehyde. Bodipyphallacidin-staining of filamentous actin (F-actin) revealed that an actin-dependent platelet adhesion supported the subsequent adhesion and spreading of neutrophils. The neutrophil ROS-response was lowered when the interaction between platelet P-selectin (CD62P) and neutrophil P-selectin glycoprotein ligand-l (PSGL-1 or CD162) was inhibited. The blocking of L-selectin (CD62L) or blocking of the interaction between platelet glycoprotein (Gp) IIb/IIIa and neutrophil complement receptor 3 (CR3) showed no effect. We conclude that platelet activation on immobilized IgG trigger a contact-dependent “frustrated” phagocytosis by neutrophils, associated with a release of toxic ROS.
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