Introduction

Most current approaches for therapy for Inflammatory Bowel Disease (IBD) focus on inhibition of excessive inflammation. However, with clinical remission rates for IBD plateauing, new approaches, are needed. The protease, Activated Protein C (APC), can exert a broad range of cytoprotective actions including inhibition of inflammation, stabilization of endothelial and epithelial barriers and suppression of apoptosis. APC shows therapeutic effects in various inflammatory diseases, and its cytoprotective functions often require biased cleavage of protease-activated receptor (PAR)1 and PAR3. Biparetide is a bivalent PAR1:PAR3-derived peptide formed by covalent linkage of PAR1-residues 47-55 to PAR3-residues 51-65 via a 10-mer oligo-Gly peptide. Biparetide in vitro mimics APC’s anti-inflammatory activity.

Aims & Methods

Aim: Our objective was to assess the in vivo therapeutic benefits of intrarectal and intraperitoneal administration of biparetide in a murine preclinical 40kDa dextran sulfate sodium (DSS) model of colitis.
Methods: Eight-week-old female C57Bl/6N mice were given 2% (weight/volume) DSS in drinking water for three 7-day cycles followed by 7 days of regular drinking water to induce colitis. Both biparetide (1, 10 and 50 mg/kg) and scrambled biparetide (peptide with randomized amino acid sequence) were given daily from day 18 to day 41 by concomitant intrarectal (half volume) and intraperitoneal (IP) injection (half volume). Anti-TNFa was administered IP 15mg/kg 3 times per week from day 18 to day 41. Prednisolone was administered IP (1mg/kg) once daily from day 18 to day 42. Control groups included healthy mice and DSS-treated animals receiving only vehicle. Colitis severity was monitored using a disease activity score (DAI) based on daily evaluation of weight, stool consistency, and presence of blood; at study end, endoscopic scoring was performed. Colon length and weight were measured, and histological analysis on formalin-fixed paraffin sections was performed by a blinded pathologist.

Results

DSS effectively induced chronic colitis. Biparetide dose-dependently reduced body weight loss compared to vehicle-dosed DSS-treated mice from day 24 (p<0.01). Biparetide at both 10 and 50 mg/kg significantly improved body weight loss compared to prednisolone (p<0.01) and anti-TNF-a from day 31 (p<0.01), and it was associated with a dose-dependent, significant reduction in DAI score compared with vehicle-dosed DSS-treated mice, e.g., from day 24 (for 10 mg/kg, p<0.01). Biparetide significantly reduced DAI compared with prednisolone (p<0.01) and reduced DAI similar to anti-TNF-a. The peptide’s protective effects against chronic colitis observed at both 10 and 50 mg/kg were accompanied by improvements in colon length shortening and in colon weight/length ratio (p<0.01), with effects comparable to anti-TNF-a. Amelioration of histological and endoscopic parameters of colitis was seen with anti-TNF-a and biparetide (10 and 50mg/kg) treatments.

Conclusion

In this DSS-induced colitis model, biparetide gave dose-dependent improvement in clinical signs and symptoms, reducing body weight loss and improving DAI score. These significant improvements were seen at 10mg/kg and 50mg/kg peptide. Similar improvements were observed during endoscopy and upon histological assessment. Here we demonstrate proof of concept that biparetide is a novel anti-inflammatory peptide that mimics APC’s previously reported in vivo benefits for DSS-induced colitis. Moreover, these data suggest that biparetide merits further evaluation for clinical translation for inflammatory pathologies.