Cathepsin B activates human trypsinogen 1 but not proelastase 2 or procarboxypeptidase B

• Background/Aims: Activation of trypsinogen to trypsin is a crucial step in the development of acute pancreatitis. The cause of this activation is not known although suggested explanations include autoactivation, cathepsin B-mediated activation and activation by mast cell tryptase. The aim of this study was to investigate cathepsin B and tryptase activation of pancreatic zymogens. Methods: Trypsinogen-1, proelastase, and procarboxypeptidase B were purified from human pancreatic juice. Human cathepsin B and beta I- tryptase are commercial products. Activation and degradation of zymogens were measured by activity towards specific substrates for trypsin and pancreatic elastase, ELISAs for procarboxypeptidase B and its activation peptide, and a radioimmunoassay for the trypsinogen activation peptide. Results: Cathepsin B caused activation of trypsinogen-1 with a trypsin yield of about 30% of that produced by enterokinase. Proelastase and procarboxypeptidase B was not activated by cathepsin B. None of the zymogens were inactivated by cathepsin B. Neither monomeric nor tetrameric tryptase could activate any of the examined zymogens. Conclusion: Cathepsin B is a competent activator of trypsinogen-1, although not as efficient as enterokinase. If cathepsin B is to play a role in protease activation in acute pancreatitis, this most probably occurs by activation of trypsinogen.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

Nyckelord

procarboxypeptidase B

proelastase

trypsinogen

cathepsin B

acute pancreatitis

tryptase

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)