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Biomaterials Research - Manfred Maitz
The Complement Systemand Kinin System
Manfred Maitz
www.manfred.maitz-online.de
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
Background• Evolutionary old system• Non specific defence system
– Constitutive • Very fast
– Selectivity and self-tolerance– Activation by antibodies possible
• Interaction with the specific immune system
• Functions– Lysis of cells/ bacteria and viruses– Opsonization for phagocytes– Immune Clearance
• Similarities and crosstalks with the clotting cascade– Cascade of serine proteases, which activate each other– Two (three) pathways of activation – Factor XIIa (Hageman-Factor) activates both the clotting cascade
and the complement cascade
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
The Membrane Attack Complex
C6 C7C8
C9
C9
C9 C9 C
9
C9 C
9 C9 C9
C9
C9
C5
C5b
C5a
70-100 Å
Biomaterials Research - Manfred Maitz
The Complement Cascade
C5
C5a
Ba Properidin
D
C3 P C3a
B
The Alternative Pathway
C3b C3bB C3bBb C3bBbP C3bBb3b
B
C3C3iC3iB
Ba
C3iBb
C3
C3a
The Tick-over Activation
C5b
C4
C4aC2 C2b C3 C3a
The Classical Pathway
Antibody + C1qrs
C4b C4b2a C4b2a3b
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
Regulation of the Complement Cascade• Short half-time of
– C3b– C3bBb– C5b
• C1 inhibitor– Inhibits the C1s activity
• Protein S in Serum– Binds to C5b67 Inhibits Formation of the Membrane Attack Complex
• HRF or CD59– Bind to C8– Inhibits C9 binding
• Factor H– Binds to C3b Facilitates binding of Factor I
cleaves C3b to inactive iC3b cleaves C4b to inactive fragments
• Decay Accelerating Factor– Increased dissociation of C3 convertase (both pathways)
Biomaterials Research - Manfred Maitz
Complement ActivationGeneral
– Hydrophobic surfaces– Oxides– Strong binding of C3(b) to nucleophilic groups (-NH2, -OH)– Higher absorption of C3 to crystalline TiO2 than to amorphous– Kallikrein directly activates C5– Plasmin directly activates C5
Classical Pathway– Antibodies IgM, IgG1, IgG2, IgG3– Lectin via the mannan binding protein (MBP) “Lectin Pathway”– Hageman Factor (F XIIa)
• Rough surfaces– C-reactive protein (CRP)– (Zirkonium, transiently)
Alternative Pathway– PE debries– Acetylated chitosan
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
Complement ReceptorsReceptor Ligand Cellular distribution
CR1 (CD35) C3b>iC3bC4b
B-CellsPhagocytesRBCfollicular dendritic cells
CR2 (CD21) iC3bC3dg
B cellsepithelial cells
CR3 (CD18/11b) iC3bZymosanICAM-1
PhagocytesNK Cellsfollicular dendritic cells
CR4 (CD18/11c) iC3b Phagocytes
Biomaterials Research - Manfred Maitz
Anaphylatoxins
Fragments C5a, C3a, C4a
• Degranulation of Phagocytes– Reactive oxygen species– Prostaglandins– Monocytes
IL-1, IL-6– Mast cells
Histamine
• Chemotaxis– Only C5a
Biomaterials Research - Manfred Maitz
Consequences in vitro
• Lysis of “innocent” neighbour cells– Red blood cells
• Activation of phagocytic cells– Release of reactive oxygen species– Release of mediators
Biomaterials Research - Manfred Maitz
Consequences in vivo• Factors of complement activation at revised hip implants
• One single study (Tang L. et al. J Biomed Mater Res 41: 333-340 (1998))
Au-Mercaptoglycerol induces strong inflammatory response in control animals.
No reaction in Complement-depleted animals.
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
The Complement Cascade
C5
C5a
Ba Properidin
D
C3 P C3a
B
The Alternative Pathway
C3b C3bB C3bBb C3bBbP C3bBb3b
B
C3C3iC3iB
Ba
C3iBb
C3
C3a
The Tick-over Activation
C5b
C4
C4aC2 C2b C3 C3a
The Classical Pathway
Antibody + C1qrs
C4b C4b2a C4b2a3b
Biomaterials Research - Manfred Maitz
Methods for Investigation
General/Common pathway– Lysis of sheep red blood cells– Solid phase methods (ELISA, RIA)
• Products: C3a, C5a, sC5b-9• Consumption of C3
– Ellipsometry
Classical Pathway– Measurement of C1qrs– Measurement of C2b or C4b2a
Alternative Pathway– Measurement of Ba or C3bBb– Measurement of Properidin
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
Biomaterials Consequences
• Testing for complement activation included in standard test programs
• Covalent binding of Factor H to the surface of a blood contacting implant– Reduced C3a, sC5b-9
• Inhibition of FXII activation by Heparin-ATIII
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
The Clotting Cascade
FibrinogenFibrinmonomers
Prothrombin I Thrombin
Factor F XaFactor F X Factor F X
F VIIF VIIa
F IXaF IX
F XIaF XI
Surface ContactCollagen
FXII activator
F XIIaF XII
F III (Tissue Thromboplastin)
Tissue/Cell Defect
Intrinsic Pathway Extrinsic Pathway
Platelet Factor 3
Ca2+
Ca2+
Ca2+
Ca2+ Ca2+
Fibrinpolymers
CrosslinkedFibrin Meshwork
F XIIIa F XIII
F VF Va
F VIIIaF VIII
Ca2+
Biomaterials Research - Manfred Maitz
The Kinin System
Effects• vascular smooth muscle relaxation• Increased permeability of blood vessels Oedema• Pain• Interaction with clotting cascade• Interaction with fibrinolytic cascade• Interaction with complement cascade
Pre-Kallikrein Kallikrein
KininogenHMWK, LMWK
Kinine.g. Bradykinin
F XIIaF XII
Surface Fibrinolytic Pathway
Plasminogen
PlasminComplement Activation
Clotting Cascade (intrinsic pathway)
Biomaterials Research - Manfred Maitz
Outline
Complement System• Background• Reactions of the complement cascade• Regulation and activation of the complement cascade• Effects of Complement activation• Evaluation methods• Consequences for biomaterials
Kinin System• Reactions and interactions with other systems
Summary and Conclusions
Biomaterials Research - Manfred Maitz
Conclusions• The blood plasma has four cascade systems
– Clotting cascade– Fibrinolytic cascade– Complement system– Kinin system
• All four systems are proteolytic cascades• Besides the main streams there are many cross connections with
minor importance– Common activators and cross activation– Common inhibitors/ regulators
• C1 Esterase Inhibitor
• Hageman Factor (F XII)– Effective in all systems– Directly activated by surfaces (esp. negatively charged)– 1-3% people have deficiencies without clinical syndromes
• Plasmin – Directly effective in three systems– Indirectly also effective on the clotting cascade
Biomaterials Research - Manfred Maitz
General ConclusionsBiomaterials research is an interdisciplinary field• Physics/Materials science
– Modification and check of physical surface properties• Roughness• Surface free energy• Hardness, tribological properties• Surface charges, electrical and electronic properties
– Bulk properties
• Chemistry– Corrosion– Polymers– Chemical surface modification– Chemical reactions of the biomolecules with the biomaterial
• Life science– Knowledge about the normal biochemical situation– Knowledge about changes at certain diseases– Check of influences due to the biomaterial– Support of the physiological situation