Proteasome inhibitors exacerbate interleukin-8 production induced by protease-activated receptor 2 in intestinal epithelial cells

Mechanisms and prevention of intestinal barrier function damage in traumatic hemorrhagic shock

The intestinal barrier is composed of mechanical barrier, chemical barrier, immune barrier, and microbial barrier, which has an important role in defense against microbial invasion. The components of intestinal barrier coordinate with each other under physiological conditions to maintain the homeostasis of intestinal internal and external environment. In traumatic hemorrhagic shock, intestinal barrier function is prone to be impaired by intestinal hypoperfusion, intestinal ischemia-reperfusion injury, and many other factors. Bacterial translocation and endotoxin entry into the blood may occur, leading to enterogenic infection, multiple organ dysfunction, and even death. At present, there are many conceptual updates and technical progress on the mechanisms, prevention, and treatment of intestinal barrier function injury in traumatic hemorrhagic shock both at home and abroad. This paper intends to make a literature review in this field based on the previous research of our team, in order to provide a systematic and comprehensive theoretical system for the clinical prevention and treatment of post-traumatic intestinal dysfunction related diseases.

PAR-1 Antagonism to Promote Gut Mucosa Healing in Crohn's Disease Patients: A New Avenue for CVT120165

A new paradigm has been added for the treatment of inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. In addition to resolving symptoms and inflammatory cell activation, the objective of tissue repair and mucosal healing is also now considered a primary goal. In the search of mediators that would be responsible for delayed mucosal healing, protease-activated receptor-1 (PAR-1) has emerged as a most interesting target. Indeed, in Crohn's disease, the endogenous PAR-1 agonist thrombin is drastically activated. Activation of PAR-1 is known to be associated with epithelial dysfunctions that hamper mucosal homeostasis. This review gathers the scientific evidences of a potential role for PAR-1 in mucosal damage and mucosal dysfunctions associated with chronic intestinal inflammation. The potential clinical benefits of PAR-1 antagonism to promote mucosal repair in CD patients are discussed. Targeted local delivery of a PAR-1 antagonist molecule such as CVT120165, a formulated version of the FDA-approved PAR-1 antagonist vorapaxar, at the mucosa of Crohn's disease patients could be proposed as a new indication for IBD that could be rapidly tested in clinical trials.

Expression of Proteinase-Activated Receptor 2 During Colon Volvulus in the Horse

Large colon volvulus in horses is associated with a poor prognosis, especially when ischemic-reperfusion injury of the affected intestinal tract develops. Proteinase-activated receptor 2 (PAR₂) plays an important role in the pathogenesis of inflammation in the gastrointestinal tract. The aim of this study was to evaluate the distribution and expression of PAR₂ in colonic pelvic flexure of horses spontaneously affected by large colon volvulus (CVH group). Eight horses admitted for severe abdominal colon volvolus and which underwent surgery were included. Colon samples were collected after enterotomy. Data previously obtained from healthy horses were used as a control group. Histologic evaluation was carried out to grade the severity of the colon lesions. Immunofluorescence, western blot and quantitative polymerase chain reaction (RT-qPCR) were carried out on colon samples to evaluate PAR₂ expression. In addition, the transcriptional profile of cytokines and chemokines was evaluated using RT² Profiler™ PCR Array Horse Cytokines & Chemokines. Three out of the eight patients were euthanised due to clinical deterioration. Immunostaining for PAR² was observed in the enterocytes, intestinal glands and neurons of the submucosal and myenteric plexi. In the CVH horses, the expression of PAR₂ mesenger RNA (mRNA) did not differ significantly from that of the healthy animals; western blots of the mucosa of the colon tracts showed a clear band of the expected molecular weight for PAR₂ (~44 kDa) and a band smaller than the expected molecular weight for PAR₂ (25kDa), suggesting its activation. The gene expressions for C-X-C motif ligand 1 (CXCL1); interleukin 8 (IL8), macrophage inflammatory protein 2 beta (MIP-2BETA) were upregulated in the colic horses as compared with the colons of the healthy horses. Therefore, in the present study, the expression and activation of PAR₂ in the colons of horses in the presence of an inflammatory reaction like that occurring in those with spontaneous colon volvulus was confirmed.

Increased protease activated receptors in the colon of patients with Hirschsprung's disease

PURPOSE

The pathophysiology of Hirschsprung's associated enterocolitis (HAEC) is not understood. Abnormal intestinal motility and altered intestinal epithelial barrier function have been suggested to play a key role in the causation of HAEC. Protease-activated receptors (PARs) 1 and 2, have been implicated in inflammatory reactions, intestinal permeability and modulation of motility in the gut.

METHODS

We investigated PAR-1 and PAR-2 protein expression in aganglionic and ganglionic regions of patients with Hirschsprung's Disease (HSCR) (n = 10) versus normal control colon (n = 10). Protein distribution was assessed by using immunofluorescence and confocal microscopy. Gene and protein expression were quantified using quantitative real-time polymerase chain reaction (qPCR), western blot analysis, and densitometry.

RESULTS

qPCR and Western blot analysis revealed that PAR-1 and PAR-2 expression was significantly increased in ganglionic and aganglionic bowel in HSCR compared to controls (p < 0.003). Confocal microscopy revealed strong PAR-1 and PAR-2 expression in smooth muscles, interstitial cells of Cajal (ICCs), platelet-derived growth factor-alpha receptor-positive (PDGFRα⁺) cells, enteric neurons and epithelium in the ganglionic and aganglionic bowel compared to controls.

CONCLUSION

Increased PAR-1 and PAR-2 expression in the colon of patients with HSCR suggests that excessive local release of PAR activating proteases may trigger inflammatory responses leading to HAEC.

Proteasome inhibitor-induced gastrointestinal toxicity

PURPOSE OF REVIEW

Gastrointestinal toxicities are commonly reported following treatment with proteasome inhibitors. The first-generation proteasome inhibitor, bortezomib, induces significant gastrointestinal side effects including nausea, vomiting, diarrhoea, and constipation, occurring in up to 84% of patients. Despite the development of safer proteasome inhibitors, such as carfilzomib, gastrointestinal toxicities remain some of the most common side effects. This review aims to summarize the previous literature on proteasome inhibitor-induced gastrointestinal toxicities, report on recent updates in the field, and investigate possible mechanisms of this toxicity.

RECENT FINDINGS

Updates in the literature have included a direct comparison of the safety of approved proteasome inhibitors, bortezomib and carfilzomib, reporting less neurotoxicity and similar gastrointestinal toxicity, from carfilzomib when compared with bortezomib. Many recent studies have investigated the safety of orally bioavailable proteasome inhibitors, such as ixazomib and oprozomib. However, little progress has been made in understanding the possible mechanisms of proteasome inhibitor-induced gastrointestinal toxicities.

SUMMARY

Although recent studies have continued to report gastrointestinal toxicities resulting from proteasome inhibitor treatment, particularly when combined with other agents or when administered orally, the mechanisms of proteasome inhibitor-induced gut toxicity remain largely unexplored. Further studies are needed to investigate the pathophysiology of this toxicity to improve the safety of existing and novel proteasome inhibitors.