Purified PEGylated porcine glucagon-like peptide-2 reduces the severity of colonic injury in a murine model of experimental colitis

The rapid degradation of porcine glucagon-like peptide-2 (pGLP-2) by the enzyme dipeptidyl peptidase-IV (DPP-IV) is the main impediment in the development of pGLP-2 as a potential therapeutic agent for intestinal dysfunction and damage. In this study, one mono-modified Lys30-polyethylene glycol (PEG)-pGLP-2 was prepared using mPEG-succinimidyl propionate. To determine the optimized condition for PEGylation, the reactions were monitored by RP-HPLC and MALDI-TOF-MS. Stability was tested in purified DPP-IV in vitro. In vivo, the protective effects for colonic injury were measured in dextran sulfate sodium (DSS)-induced colitis in mice. The monoPEGylated products reached the maximum yield at 4:1 ratio of mPEG5k-SPA to pGLP-2. An effective method of successfully separating PEGylated pGLP-2 from mPEG-SPA5kD using CM Sepharose Fast Flow resin was established. The half-life of Lys30-PEG-pGLP-2 was 16-fold longer than that of pGLP-2 in DPP-IV. The DSS mice exhibited marked weight loss), which was significantly reduced by Lys30-PEG-pGLP-2 therapy. DSS treatment significantly increased colonic damage score, which was significantly reduced by administration of Lys30-PEG-pGLP-2 in DSS-mice. DSS-induced colitis clearly induced Myeloperoxidase activity in the colon, which was significantly reduced by treatments with 3% DSS-pGLP-2 or 3% DSS-PEG-pGLP-2. These results showed that site-specific Lys30-PEG-GLP-2 was resistant to degradation and reduced the severity of colonic injury in murine colitis. The enhanced biological potency of this product highlighted its potential as a therapeutic agent for intestinal diseases.