Comparative efficacies of 2 cysteine prodrugs and a glutathione delivery agent in a colitis model

Abstract

Oxidant-mediated injury plays an important role in the pathophysiology of inflammatory bowel disease (IBD). Recently, antioxidants were shown to modulate colitis in mice. In this study, the protective effects of L-cysteine and glutathione (GSH) prodrugs are further evaluated against progression of colitis in a murine model. ICR mice were fed compounds incorporated into chow as follows: Group (A) received chow supplemented with vehicle. Group (B) was provided 2-(RS)-npropylthiazolidine-4(R)-carboxylic-acid (PTCA), a cysteine prodrug. Group (C) received D-ribose-L-cysteine (RibCys), another cysteine prodrug that releases L-cysteine. Group (D) was fed Lcysteine-glutathione mixed sulfide (CySSG), a ubiquitous GSH derivative present in mammalian cells. After 3 days, the animals were further provided with normal drinking water or water supplemented with dextran sodium sulfate (DSS). Mice administered DSS developed severe colitis and suffered weight loss. Colonic lesions significantly improved in animals treated with PTCA and RibCys and, to a lesser extent, with CySSG therapy. Hepatic GSH levels were depleted in colitis animals (control vs DSS, P < 0.001), and normalized with prodrug therapies (control vs treatments, P > 0.05). Protein expressions of serum amyloid A and inflammatory cytokines [interleukin (IL)-6, IL-12, tumor necrosis factor-alpha (TNF-α), osteopontin (OPN)] were significantly increased in colitis animals and improved with therapies. Immunohistochemistry and Western blot analyses showed significant upregulation of the macrophage-specific markers, COX-2 and CD68, which suggests macrophage activation and infiltration in the colonic lamina propria in colitis animals. These abnormalities were attenuated in prodrug-treated mice. In conclusion, these data strongly support the novel action of the PTCA against colitis, which further supports a possible therapeutic application for IBD patients.Inflamed gut from ulcerative colitis and Crohn's disease patients is rich in activated macrophages and neutrophils. These inflammatory cells generate excess amounts of reactive oxygen species (ROS) with subsequent increased oxidative stress. 1 The increased generation of highly toxic ROS exceeds the limited intestinal antioxidant defense system, thereby contributing to intestinal oxidative injury in ulcerative colitis patients. 2 Excessive production of ROS has been demonstrated in circulating phagocytic and polymorphonu-clear leukocytes cells in inflammatory bowel disease (IBD) patients, using a chemiluminescence assay 3 and after stimulation with the bacterial chemotactic peptide, N-formyl-methionyl-leucylphenylalanine. 4 Thus, oxidant-mediated injury plays an important role in the pathophysiology of IBD. The endogenous tripeptide, glutathione (GSH), is the most important intracellular defense agent in mammalian organs, including the gut. GSH is involved in protein folding and protein synthesis as well as in intracellular signaling. 5 GSH may be depleted during inflammatory insults, and GSH-deficient mice show s...

Osteopontin expression by CD103−dendritic cells drives intestinal inflammation

“…Opn expression is up-regulated in peripheral blood and intestinal mucosa of patients (24)(25)(26)(27)(28)(29) and mice with IBD (14,15,27,30). We found that Opn protein and mRNA (Spp1) levels were also significantly higher in MLN cells (MLNCs) from mice with acute colitis (∼fourfold and ∼46-fold, respectively) compared with healthy mice (Fig.…”

“…Opn is expressed by DCs and other immune cell types, such as lymphocytes, during autoimmune responses (16)(17)(18)(19)(20)(21)(22), and its expression by DCs during autoimmunity contributes to disease severity (17-19, 21, 23). In addition, Opn expression is highly up-regulated in intestinal immune and nonimmune cells and in the plasma of patients with CD and UC (24)(25)(26)(27)(28)(29), as well as in the colon and plasma of mice with experimental colitis (14,15,27,30). Increased plasma Opn levels are related to the severity of CD inflammation (29), and certain Opn gene (Spp1) haplotypes are modifiers of CD susceptibility (31), indicating that Opn could be used as an IBD biomarker (27).…”

Impaired Thiol-Disulfide Balance in Acute Brucellosis

“…Cysteine has been reported to show anti-inflammatory effects (14). Drugs that contain cysteine have been used to cure intestinal inflammation and have created promising outcomes (13). In a recent study, the free amino acid form, L-cysteine, was deployed against inflammatory bowel disease (37).…”

“…For example, proteins that include sulfhydryl groups and glutathione are accepted as endogenous anti-inflammatory mediators against the reactive oxygen species produced by activation of NADPH oxidase within polymorph nuclear neutrophils in inflammation and tissue damage (13). Thiol antioxidants such as glutathione and N-acetylcysteine inhibit cytokine production (14).…”

Osteopontin Biomarker in Inflammatory Bowel Disease, Animal Models and Target for Drug Discovery

“…On the basis of these findings, several researchers described animal models that can mimic the OPN-induced colitis in vivo as well as block OPN-induced inflammation [20][21][22][23].…”