Biomaterials ResearchBiomaterials Research - Manfred Maitz The Complement System and Kinin System...

Biomaterials Research - Manfred Maitz

The Complement Systemand Kinin System

Manfred Maitz

www.manfred.maitz-online.de

http://www.fz-rossendorf.de/


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



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



Outline






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



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



Outline






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)



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



Outline






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



Anaphylatoxins

Fragments C5a, C3a, C4a

• Degranulation of Phagocytes– Reactive oxygen species– Prostaglandins– Monocytes

IL-1, IL-6– Mast cells

Histamine

• Chemotaxis– Only C5a



Consequences in vitro

• Lysis of “innocent” neighbour cells– Red blood cells

• Activation of phagocytic cells– Release of reactive oxygen species– Release of mediators



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.



Outline






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



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



Outline






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



Outline






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+



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)



Outline






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





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


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