Local Colonic Administration of a Serine Protease Inhibitor Improves Post-Inflammatory Visceral Hypersensitivity in Rats

Abstract

Dysregulation of the protease–antiprotease balance in the gastrointestinal tract has been suggested as a mechanism underlying visceral hypersensitivity in conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). We aimed to study the potential therapeutic role of an intracolonically administered serine protease inhibitor for the treatment of abdominal pain in a post-inflammatory rat model for IBS. An enema containing 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in male Sprague–Dawley rats, whereas controls received a saline solution. Colonoscopies were performed to confirm colitis and follow-up mucosal healing. In the post-inflammatory phase, the serine protease inhibitor UAMC-00050 (0.1–5 mg/kg) or its vehicle alone (5% DMSO in H2O) was administered in the colon. Thirty minutes later, visceral mechanosensitivity to colorectal distensions was quantified by visceromotor responses (VMRs) and local effects on colonic compliance and inflammatory parameters were assessed. Specific proteolytic activities in fecal and colonic samples were measured using fluorogenic substrates. Pharmacokinetic parameters were evaluated using bioanalytical measurements with liquid chromatography–tandem mass spectrometry. Post-inflammatory rats had increased trypsin-like activity in colonic tissue and elevated elastase-like activity in fecal samples compared to controls. Treatment with UAMC-00050 decreased trypsin-like activity in colonic tissue of post-colitis animals. Pharmacokinetic experiments revealed that UAMC-00050 acted locally, being taken up in the bloodstream only minimally after administration. Local administration of UAMC-00050 normalized visceral hypersensitivity. These results support the role of serine proteases in the pathophysiology of visceral pain and the potential of locally administered serine protease inhibitors as clinically relevant therapeutics for the treatment of IBS patients with abdominal pain.

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

“…To date, the underlying pathophysiology of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) is not entirely elucidated, but a key role for proteases has been described [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. The involvement of these proteases in IBS and IBD has been studied by evaluating their expression and activity in rodent models and patients.…”

“…Likewise, it was shown that colonic samples from animal models of dextran sulfate sodium (DSS) and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in the acute phase, as a model for IBD, and in colonic samples during the post-inflammatory (post-colitis) phase, as a model for IBS, showed increased trypsin-like activity as well. This activity was measured with small fluorogenic and chromogenic substrates [ 10 , 12 , 13 ].…”

“…Furthermore, fecal supernatant from IBS patients showed increased trypsin-like, chymotrypsin-like, neutrophil elastase, proteinase-3 and cathepsin G activity [ 9 , 16 ]. Fecal samples from a TNBS-induced post-colitis rat model also showed an increased elastase-like activity [ 13 ].…”

The Effect of a Novel Serine Protease Inhibitor on Inflammation and Intestinal Permeability in a Murine Colitis Transfer Model

“…A method to influence the protease signaling pathways is to directly alter protease activity by using selective inhibitors ( Vergnolle, 2016 ). In this respect, we previously developed selective serine protease inhibitors (patents WO/2007/045496, WO/2017/198753) ( Joossens et al, 2007 ) and recently showed their in vivo therapeutic potential in inflammation-induced visceral hypersensitivity ( Ceuleers et al, 2018 ; Hanning et al, 2021b ) and dry eye derived ocular inflammation ( Joossen et al, 2020 ). Besides, UAMC-00050 displays a favorable inhibitory profile with a good inhibition of the serine protease tryptase, together with a limited inhibition of proteases involved in the coagulation cascade ( Ceuleers et al, 2018 ).…”

“…Besides, UAMC-00050 displays a favorable inhibitory profile with a good inhibition of the serine protease tryptase, together with a limited inhibition of proteases involved in the coagulation cascade ( Ceuleers et al, 2018 ). Furthermore, we recently demonstrated that the pharmacokinetic properties of UAMC-00050 are suitable for translation to a clinical setting, since the compound is only minimally detected in blood samples after local colonic administration ( Hanning et al, 2021b ). These promising results formed the basis of this study aiming at investigating the effect of the trypsin-like serine protease inhibitor UAMC-00050 on intestinal permeability and intestinal inflammation in a mouse model of chronic colitis.…”