1. Figure 4 Cascade system activation on a biomaterial surface
Figure 4 | Cascade system activation on a biomaterial surface. On contact with blood, the surface of a biomaterial is immediately covered with a layer of plasma proteins by passive adsorption. Recognition of the surface occurs via two different mechanisms. Negatively charged surfaces tend to bind factor XII (FXII), which induces activation of the contact system, and C1q and properdin, which initiate or modulate complement activation via the classical and alternative pathway, respectively. On hydrophilic surfaces, certain proteins bind in altered, surface-activated conformations. These proteins include FXII, which activates the contact system; C3 (Ref. 112), which in the form of C3(H2O) can activate the alternative pathway of complement; and non-antigen bound IgG, which activates the classical pathway of complement. Activation and amplification of the complement system generates anaphylatoxins that recruit and activate polymorphonuclear cells (PMNs) and monocytes, thereby inducing an inflammatory response, whereas activation of the coagulation system generates thrombin, which recruits platelets and catalyses fibrin formation. Substantial crosstalk between the activated components of the cascade systems leads to further amplification of inflammatory and pro-thrombotic processes. Ab, antibody; Bb, activated factor B; C5aR, C5a anaphylatoxin chemotactic receptor 1; FcγR, Fcγ receptor; HK, high molecular weight kininogen; PAR1/4, proteinase-activated receptor 1/4; P2Y1/12, P2Y purinoceptor 1/12.
Ekdahl, K. N. et al. (2017) Cardiovascular disease in haemodialysis: role of the intravascular innate immune system
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