metallothionein and Inflammatory-Bowel-Diseases

Immunological disorders, increased oxidative stress, and damage to the epithelial barrier play an important role in the pathogenesis of inflammatory bowel diseases (IBDs). In the treatment of patients with Crohn's disease (CD) and ulcerative colitis (UC), it is increasingly common to use biological drugs that selectively affect individual components of the inflammatory cascade. However, administering the medicines currently available does not always result in obtaining and maintaining remission, and it may also lead to the development of resistance to a given agent over time. Metallothioneins (MTs) belong to the group of low molecular weight proteins, which, among others, regulate the inflammation and homeostasis of heavy metals as well as participating in the regulation of the intensity of oxidative stress. The results of the studies conducted so far do not clearly indicate the role of MTs in the process of inflammation in patients with IBD. However, there are reports that suggest the possibility of using MTs as a potential target in the treatment of this group of patients.

Topics: Colitis, Ulcerative; Crohn Disease; Humans; Inflammatory Bowel Diseases; Metallothionein; Oxidative Stress

Inflammatory bowel disease (IBD) is a group of disorders characterized by chronic inflammation within the gastrointestinal tract. It is a multifactorial disease associated with immune-cell mediated oxidative damage to the intestinal mucosa. There is no cure for IBD, but anti-cytokine therapy can limit target inflammation and disease progression. Unfortunately, many patients are nonresponsive or develop resistance to anti-cytokine therapy over time creating a need for new therapeutic agents. Metallothionein (MT) is a small, highly conserved stress response protein that has been shown to modulate the immune response as a pro-inflammatory agent, regulates divalent heavy metal homeostasis, and acts as a reactive metabolite scavenger. Our research, as well as other groups studying MT, has described MT induction and release during IBD inflammatory stress response. The release of MT results in activation of inflammatory responses leading to progressive inflammation and subsequent expansion of MT synthesis. A monoclonal antibody specific for MT has been used in murine models of IBD and should only target the extracellular pool of MT, thus representing a novel therapeutic approach to this disease.

Topics: Animals; Antibodies, Monoclonal; Humans; Immunotherapy; Inflammatory Bowel Diseases; Metallothionein

Inflammatory bowel diseases (IBDs) are a group of chronic, relapsing, immune-mediated disorders of the intestine, including Crohn's disease and ulcerative colitis. Recent studies underscore the importance of the damaged epithelial barrier and the dysregulated innate immune system in their pathogenesis. Metallothioneins (MTs) are a family of small proteins with a high and conserved cysteine content that are rapidly upregulated in response to an inflammatory stimulus. Herein, we review the current knowledge regarding the expression and potential role of MTs in IBD. MTs exert a central position in zinc homeostasis, modulate the activation of the transcription factor nuclear factor (NF)-kappaB, and serve as antioxidants. In addition, MTs could be involved in IBD through their antiapoptotic effects or through specific immunomodulating extracellular effects. Reports on MT expression in IBD are contradictory but clearly demonstrate a deviant MT expression supporting the idea that these aberrations in IBD require further clarification.

Topics: Animals; Colitis; Disease Models, Animal; Humans; Inflammatory Bowel Diseases; Metallothionein; Models, Biological

A positive-feedback mechanism between hypoxia-inducible factor 1 alpha (HIF-1α) and metallothioneins (MTs) has been identified in different diseases. Both proteins have been independently proposed in the pathogenesis of inflammatory bowel disease (IBD); however, their relation has never been studied in the gut. In this study, we investigated the interaction between HIF-1α and MTs in colonic epithelial cells and during experimental colitis. Dimethyloxalylglycine (DMOG) was used to subject colonocytes to hydroxylase inhibition and HIF-1α stabilization in three experimental models (in vitro, in vivo and ex vivo). Small interfering RNA targeting HIF-1α (siRNA-HIF) and MT (siRNA-MT) together with zinc-mediated MT induction were used to study the interaction between HIF-1α and MT in HT29 cells. Acute colitis was induced in C57BL/6 mice using dextran sulphate sodium. MT expression and HIF-1α protein levels were measured using quantitative real-time PCR and ELISA, respectively. Vascular endothelial growth factor (VEGF) expression was quantified as an indirect measure of HIF-1 transcriptional activity. DMOG down-regulated MT expression in HT29 cells, in freshly isolated human colonocytes and in colonocytes isolated from mice treated with DMOG (p<0.05). SiRNA-HIF-treated cells displayed significant higher basal MT levels (p<0.05) and an attenuated MT down-regulation after DMOG treatment. In turn, HIF-1α stabilization was significantly lower in zinc-treated control cells, displaying high MT levels, compared to siRNA-MT cells treated with DMOG (p<0.05). In the course of experimental colitis, MT and VEGF mRNA expression were inversely related. MTs were induced in the acute phase and down-regulated during recovery. Opposing results were observed for VEGF expression levels (p<0.05). The present study underscores the inverse relation between HIF-1α and MT expression in colonocytes and during experimental colitis. The manipulation of MTs may represent a novel therapeutic strategy for patients suffering from IBD.

Topics: Amino Acids, Dicarboxylic; Animals; Colitis; Colon; Down-Regulation; HT29 Cells; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Inflammatory Bowel Diseases; Metallothionein; Mice; Mice, Inbred C57BL; Models, Animal; RNA, Small Interfering; Vascular Endothelial Growth Factor A; Zinc

We evaluated whether modulation of metallothionein (MT, and subsequent oxidative stress) would influence the development and progression of colitis.. MT-transgenic (MT-TG), MT-knockout (MT-KO), and wild-type (WT) mice were treated with Dextran Sodium Sulfate (DSS) to induce colitis compared to controls (no DSS).. The DSS treated MT-TG and MT-KO mice responded in a manner similar to that of DSS treated WT mice, with all groups developing severe colitis. The colonic MT content in DSS treated animals increased drastically when compared to controls. The colonic and blood levels of the antioxidant, glutathione (GSH), were significantly reduced in DSS treated MT-TG and MT-KO mice. Howevei there was no significant difference in the cysteine levels in these mice. The subeellular level of MT was highest in intestinal crypts loci of MT-TG mice and was not observed in MT-KO mice as well as in the inflammatory lesions.. We conclude that MT does not appear to influence the development or progression of intestinal pathology in the DSS animal model of IBD.

Topics: Animals; Colitis; Colon; Dextran Sulfate; Disease Models, Animal; Gene Expression; Humans; Immunohistochemistry; Inflammatory Bowel Diseases; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic

Metallothionein (MT) expression in intestinal resection specimens from 41 patients with ulcerative colitis (UC) and 10 patients with Crohn's disease (CD ) was immunohistochemically studied by the avidin-biotin (ABC) method. In addition, the possible relationship of its expression with HLA-DR antigen expression, lymphocyte subpopulations and proliferation-associated indices was studied in order to elucidate the role of this molecule in inflammatory bowel disease (IBD). The MT immunoreactivity was recorded by staining and intensity-distribution scores. MT staining varied in and was mainly localized in the cytoplasm, although a combined nuclear/cytoplasmic reactive pattern was also seen in epithelial cells. MT expression was decreased in UC, and CD compared with normal mucosa. No difference in MT expression between UC and CD was noted. In UC, a gradually decreased expression from remission, to resolving and to active phase was observed. An inverse correlation of MT expression with HLA-DR antigen expression was detected (p = 0.018) in the cases of UC. The data suggest that a low level of MT expression in inflammatory bowel disease and particularly in active phase of UC may indicate a decreased endogenous intestinal protection and it may be implicated in the pathogenesis of the disease.

Topics: Antigens, CD; Antigens, Differentiation, Myelomonocytic; Cell Division; Epithelium; Female; HLA-DR Antigens; Humans; Immunohistochemistry; Inflammatory Bowel Diseases; Intestine, Large; Lymphocyte Subsets; Male; Metallothionein; Middle Aged

Intestinal mucosal damage in the inflammatory bowel diseases (IBD) Crohn's disease (CD) and ulcerative colitis (UC) involves reactive oxygen metabolites (ROMs). ROMs are neutralized by endogenous antioxidant enzymes in a carefully balanced two-step pathway. Superoxide dismutases (SODs) convert superoxide anion to hydrogen peroxide (H(2)O(2)), which is subsequently neutralized to water by catalase (CAT) or glutathione peroxidase (GPO). Remarkably changed expression levels of the three isoforms of SOD in paired non-inflamed and inflamed mucosae from CD and UC patients have been previously reported in comparison to normal control mucosa. Most notable was the strong up-regulation of Mn-SOD in inflamed epithelium. It was hypothesized that in order to provide optimal protection against ROM-mediated damage, these changes should be coordinately counterbalanced by an increased H(2)O(2)-neutralizing capacity. Therefore, the same tissue samples were used to assess the levels, activities, and/or localization of the most prominent mucosal H(2)O(2)-related antioxidants CAT, GPO, glutathione (GSH), myeloperoxidase (MPO), and metallothionein (MT). Quantitative measurements showed that in both CD and UC patients, intestinal inflammation was associated with increased activities of CAT, GPO, and MPO, whereas the mucosal GSH content was unaffected and the concentration of MT was decreased. Despite this overall increase in mucosal H(2)O(2)-metabolizing enzyme capacity, immunohistochemical analysis revealed a differentially disturbed antioxidant balance in IBD epithelium and lamina propria. In the lamina propria, the risk of direct H(2)O(2)-mediated damage seemed to be restrained by the increasing numbers of CAT- and MPO-positive monocytes/macrophages and neutrophils that infiltrated the inflamed areas. On the other hand, MPO overexpression might increase the lamina propria levels of hypochlorous acid, a stable ROM with multiple pro-inflammatory effects. In the epithelium, the number of cells that expressed CAT remained unchanged during inflammation and GPO was found in only a very low and constant number of epithelial cells. In addition, the inflamed epithelium displayed decreased expression of the hydroxyl radical (OH(*)) scavenger MT. In view of the high epithelial SOD levels in inflamed IBD epithelium, it is speculated that the efficient removal of excess H(2)O(2) is hampered in these cells, thereby increasing not only the risk of detrimental effects of H(2)O(2) directly,

Topics: Adult; Aged; Aged, 80 and over; Antioxidants; Catalase; Female; Glutathione; Glutathione Peroxidase; Humans; Immunoenzyme Techniques; Inflammatory Bowel Diseases; Intestinal Mucosa; Male; Metallothionein; Middle Aged; Oxidative Stress; Peroxidase

Metallothioneins (MT) are cytoprotective against the damaging effects of oxygen-derived free radicals. Therefore MT may be involved in defence mechanisms to counter Crohn's disease (CD) and ulcerative colitis (UC).. 107 routinely processed tissue samples from 22 patients with CD and 48 patients with UC were tested with the monoclonal anti-MT antibody E9.. Immunohistochemistry was used to assess MT staining in a semiquantitative manner. Chi-square test was used for statistical analysis.. MT overexpression was found in the fibroblasts of all ulcerative and/or fissural lesions in UC and CD. MT overexpression in intestinal epithelial cells of 40% of UC and CD lesions correlated significantly with the grade of inflammation.. MT-immunoreactivity in fibroblasts supports a protective role for MT in inflammatory bowel disease. It remains unclear whether MT overexpression in epithelial cells is also important in this protection.

Topics: Humans; Immunohistochemistry; Inflammatory Bowel Diseases; Metallothionein