Increased Mucosal Thrombin is Associated with Crohn’s Disease and Causes Inflammatory Damage through Protease-activated Receptors Activation

Abstract

Background and Aims Thrombin levels in the colon of Crohn’s disease patients have recently been found to be elevated 100-fold compared to healthy controls. Our aim was to determine whether and how dysregulated thrombin activity could contribute to local tissue malfunctions associated with Crohn’s disease. Methods Thrombin activity was studied in tissues from Crohn’s disease patients and healthy controls. Intracolonic administration of thrombin to wild-type or protease-activated receptor-deficient mice was used to assess the effects and mechanisms of local thrombin upregulation. Colitis was induced in rats and mice by the intracolonic administration of trinitrobenzene sulfonic acid. Results Active forms of thrombin were increased in Crohn’s disease patient tissues. Elevated thrombin expression and activity were associated with intestinal epithelial cells. Increased thrombin activity and expression were also a feature of experimental colitis in rats. Colonic exposure to doses of active thrombin comparable to what is found in inflammatory bowel disease tissues caused mucosal damage and tissue dysfunctions in mice, through a mechanism involving both Protease-Activated Receptors-1 and -4. Intracolonic administration of the thrombin inhibitor Dabigatran, as well as inhibition of protease-activated receptor-1, prevented trinitrobenzene sulfonic acid-induced colitis in rodent models. Conclusions Our data demonstrated that increased local thrombin activity, as it occurs in the colon of patients with inflammatory bowel disease, causes mucosal damage and inflammation. Colonic thrombin and protease-activated receptor-1 appear as possible mechanisms involved in mucosal damage and loss of function and therefore represent potential therapeutic targets for treating inflammatory bowel disease.

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

“…An increased thrombin activity was measured in colonic samples from patients with Crohn’s disease. This increased activity and an increased thrombin expression were also observed in colonic tissue from TNBS-induced acute colitis rats [ 11 ]. A second trypsin-like protease reported to be involved in both IBD and IBS is tryptase [ 2 , 3 , 4 , 14 ].…”

“…There is ample evidence in literature for the involvement of proteases in IBS and IBD [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Most studies rely on the use of synthetic substrates for trypsin-like and elastase-like enzymes that are often not capable of making further refinements towards the specific proteases involved [ 4 , 8 , 9 , 10 , 11 , 12 , 13 , 16 ].…”

“…There is ample evidence in literature for the involvement of proteases in IBS and IBD [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Most studies rely on the use of synthetic substrates for trypsin-like and elastase-like enzymes that are often not capable of making further refinements towards the specific proteases involved [ 4 , 8 , 9 , 10 , 11 , 12 , 13 , 16 ]. We used the cleavage patterns of peptides based on in vivo occurring substrates to further identify specific proteases pointing to a set of proteases as potential targets for therapy in the acute and post-inflammatory phase of a TNBS-induced colitis rat model.…”

“…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.…”

Gut Serpinome: Emerging Evidence in IBD

“…Such deregulated proteolytic activity was shown to participate in the inflammatory response and to cause structural and functional alterations in the gut epithelium through (i) the activation of protease-activated receptor (PAR), (ii) the cleavage of junctional protein and (iii) the processing of cytokines and chemokines. A recent study demonstrated that the pro-inflammatory effects of colonic thrombin, whose activity showed a 100-fold increase in the biopsies of IBD patients [ 60 ], are mediated through the activation of PAR1 and PAR4 [ 61 ]. Only PAR1 inhibition prevents 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats.…”