Protective Effects of Pegylated Choline Acetyltransferase in a Murine Model of DSS Colitis.

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, affects up to 3 million people in the United States alone, significantly worsens a patient's quality of life, and is associated with a high financial burden. Current treatments for IBD are mainly biologicals that have significant side effects. No efficient pharmacological treatments are currently available for IBD. Previous studies established that activation of the vagus nerve-based inflammatory reflex inhibits cytokine production and regulates immune responses through cholinergic signaling. Acetylcholine released by a T cell subset expressing choline acetyltransferase (ChAT), the enzyme that catalyzes the biosynthesis of acetylcholine, inhibits cytokine production via signaling through α7 nicotinic acetylcholine receptors (α7nAChR). However, the possibility of controlling inflammation by systemic administration of ChAT is unexplored. Here we examined the efficacy of ChAT in improving disease activity in a preclinical model of colitis. To prolong the half-life of circulating ChAT, the protein was modified by covalently attaching repeating units of polyethylene glycol (PEG), resulting in enzymatically active PEG-ChAT. We utilized a well-established model of colitis - dextran sulfate sodium induced colitis. Wild type C57/black 6 mice were exposed to 4% DSS (M.W 36 000-50 000) in drinking water for 7 days prior to administration of PEG-ChAT. Starting on day 8, animals received PEG-ChAT or vehicle intraperitoneally twice per day for 7 days. PEG- ChAT treated mice showed a significantly lower disease activity index as compared with vehicle treated controls with the disease (d11 p=0.006 ChAT mice: 0.17DAI±0.05, n=9 versus vehicle mice: 0.66DAI±0.13, n=10). The decreased severity of colitis in PEG-ChAT-treated mice as compared with vehicle-treated controls is further demonstrated by a significant improvement in body weight gain (d14 p=0.01 ChAT mice: -5.1%±1.1, n=10 versus vehicle mice: -15.5%±2.9, n=10) and colon length (p=0.006 ChAT mice: 7.15cm±0.2, n=10 versus vehicle mice: 6.2cm±0.2, n=10). In conclusion, PEG-ChAT reduces disease activity in a preclinical model of colitis. Together these studies provide new insights into the role of PEG-ChAT as an experimental anti-inflammatory therapeutic modality for the treatment of IBD.