Pathophysiology of the interaction between complement and non-complement proteases

The role of complement in biomaterial-induced inflammation

Biomaterials are regularly used in various types of artificial tissues and organs, such as oxygenators, plasmapheresis equipment, hemodialysers, catheters, prostheses, stents, vascular grafts, miniature pumps, sensors and heart aids. Although progress has been made regarding bioincompatibility, many materials and procedures are associated with side effects, in particular bioincompatibility-induced inflammation, infections and subsequent loss of function. After cardiopulmonary bypass, coagulopathies can occur and lead to cognitive disturbances, stroke and extended hospitalization. Hemodialysis is associated with anaphylatoid reactions that cause whole-body inflammation and may contribute to accelerated arteriosclerosis. Stents cause restenosis and, in severe cases, thrombotic reactions. This situation indicates that there is still a need to try to understand the mechanisms involved in these incompatibility reactions in order to be able to improve the biomaterials and to develop treatments that attenuate the reactions and thereby reduce patients' discomfort, treatment time and cost. This overview deals with the role of complement in the incompatibility reactions that occur when biomaterials come in contact with blood and other body fluids.

Effects on peritoneal proteolysis and hemodynamics of prophylactic infusion with C1 inhibitor in experimental acute pancreatitis

Acute pancreatitis was induced in pigs by manual retrograde injection of Na-taurocholate into the pancreatic duct. Chromogenic peptide substrate assays showed increased trypsin (TRY) and plasma kallikrein activities (KK), parallel with a reduction of prekallikrein (PKK) levels and functional plasma kallikrein inhibition (KKI), in the peritoneal exudate in untreated animals. Pretreatment with C1 inhibitor (C1 INH) concentrate significantly increased the KKI capacity, parallel with unchanged KK and TRY activities in the peritoneal exudate. Furthermore, C1 INH pretreatment significantly improved the hemodynamic performance and the survival rate during a 6-h observation period. The study underlines the pathophysiological importance of trypsin and the plasma kallikrein-kinin system during acute pancreatitis. C1 INH concentrates given intravenously prevent activation of this system locally in the peritoneal exudate during experimental acute pancreatitis.