Proteolytic Cleavage of Bioactive Peptides and Protease-Activated Receptors in Acute and Post-Colitis

Area of Science:

• Gastroenterology
• Biochemistry
• Proteomics

Background:

• Inflammatory bowel disease (IBD) involves complex protease dysregulation.
• Previous studies utilized synthetic substrates, limiting insights into bioactive peptide processing.
• Understanding protease activity in IBD pathogenesis is crucial for therapeutic development.

Purpose of the Study:

• To investigate protease activity in colonic tissue from a rat model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis.
• To identify specific bioactive peptides cleaved by proteases during acute and post-inflammatory phases of colitis.
• To correlate protease activity with specific enzyme classes and potential therapeutic targets in IBD.

Main Methods:

• Utilized a TNBS-induced colitis rat model.
• Analyzed colonic tissue proteases by incubating them with relevant bioactive peptides.
• Identified peptide cleavage patterns using mass spectrometry.
• Correlated observed cleavages with specific protease activities (thrombin, chymotrypsin-like, trypsin-like).

Main Results:

• Increased cleavage of several bioactive peptides was observed in acute colitis samples.
• Tethered ligand (TL) sequences of protease-activated receptors (PAR) 1 and 4 were significantly unmasked, correlating with thrombin activity.
• Increased cleavage of β-endorphin and altered PAR3-based peptide processing were linked to chymotrypsin-like activity.
• Enkephalin processing suggested involvement of proteases beyond trypsin- or chymotrypsin-like enzymes.

Conclusions:

• Protease activity, particularly involving thrombin, chymotrypsin-like enzymes, and other specific proteases, is significantly altered during acute colitis.
• These identified proteases represent potential therapeutic targets for managing inflammatory bowel disease.