metallothionein and Crohn-Disease

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

Metallothioneins (MTs) are ubiquitous metal-binding proteins that have been highly conserved throughout evolution. Although their physiological function is not completely understood, they are involved in diverse processes including metal homeostasis and detoxification, the oxidative stress response, inflammation, and cell proliferation. Te human MT gene family consists of at least 18 isoforms, containing pseudogenes as well as genes encoding functional proteins. Most of the MT isoforms can be induced by a wide variety of substances, such as metals, cytokines, and hormones. Different cell types express discrete MT isoforms, which reflects the specifically adapted functions of MTs and a divergence in their regulation. Te aberrant expression of MTs has been described in a number of diseases, including Crohn's disease, cancer, Alzheimer's disease, amyotrophic lateral sclerosis, Menkes disease, and Wilson's disease. Therefore, a thorough understanding of MT gene regulation is imperative. To date, the transcriptional regulation of MTs has primarily been studied in mice. While only four murine MT isoforms exist, the homology between murine and human MTs allows for the evaluation of the regulatory regions in their respective promoters. Here, we review the aberrant expression of MTs in human diseases and the mechanisms that regulate MT1 expression based on an in silico evaluation of transcription factor binding sites.

Topics: Alzheimer Disease; Animals; Crohn Disease; Gene Expression Regulation; Hepatolenticular Degeneration; Humans; Menkes Kinky Hair Syndrome; Metallothionein; Mice; Neoplasms; Phylogeny; Promoter Regions, Genetic

Metallothioneins (MTs) are excellent candidate genes for Inflammatory Bowel Disease (IBD) and have previously been shown to have altered expression in both animal and human studies of IBD. This is the first study to examine genetic variants within the MT genes and aims to determine whether such genetic variants have an important role in this disease. 28 tag SNPs in genes MT1 (subtypes A, B, E, F, G, H, M, X), MT2, MT3 and MT4 were selected for genotyping in a well-characterized New Zealand dataset consisting of 406 patients with Crohn's Disease and 638 controls. We did not find any evidence of association for MT genetic variation with CD. The lack of association indicates that genetic variants in the MT genes do not play a significant role in predisposing to CD in the New Zealand population.

Topics: Adolescent; Adult; Case-Control Studies; Crohn Disease; Female; Gene Frequency; Genetic Predisposition to Disease; Humans; Linkage Disequilibrium; Male; Metallothionein; Middle Aged; New Zealand

Oxygen derived radicals contribute to tissue injury in inflammatory bowel disease. We measured the content of superoxide dismutase and metallothionein (two endogenous copper and zinc containing proteins involved in radical scavenging) in intestinal resection specimens from 29 patients with Crohn's disease and 12 patients with ulcerative colitis and compared the concentrations with those obtained in the normal mucosa of a control group of 18 patients with colorectal cancer. The superoxide dismutase content was similar in control mucosa and non-inflamed mucosa from patients with inflammatory bowel disease (mean (SEM) 2.13 (0.10) and 2.24 (0.10) mg/g protein, respectively) but was decreased in inflamed mucosa (1.87 (0.08) mg/g protein, p less than 0.005 v non-inflamed mucosa). The metallothionein content was decreased in non-inflamed inflammatory bowel disease mucosa compared with control mucosa (0.23 (0.03) and 0.36 (0.04) mg/g protein, respectively, p less than 0.02) and a further decrease was found in inflamed mucosa (0.17 (0.02) mg/g protein, p less than 0.001 v control mucosa). No differences were found between Crohn's disease and ulcerative colitis and no significant effect of medication or tissue localisation was noted. These findings might indicate a decreased endogenous intestinal protection against oxygen derived radicals in inflammatory bowel disease which could contribute to the pathogenesis of the disease.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Colitis, Ulcerative; Colon; Crohn Disease; Female; Humans; Ileum; Intestinal Mucosa; Male; Metallothionein; Middle Aged; Oxidation-Reduction; Superoxide Dismutase

Antibody to rat liver metallothionein prepared by the method of Brady and Kafka (1979) was used to localise immunoreactive metallothionein using a sensitive DNP hapten sandwich technique applied to formalin fixed wax embedded tissues. Rat tissues examined were liver, kidney and small intestine, taken from normal animals, from animals fasted after receiving either an oral dose of water, or 1 ml zinc acetate solution either orally or by intraperitoneal injection, (3-4 mg Zn++/Kg body weight). Human tissues examined were 6 histologically normal liver biopsies and small intestine including histologically normal jejunal biopsies and samples of ileum obtained at operation. Pathological tissue including liver from cases of Indian childhood cirrhosis with copper retention and ileum from cases of inflammatory bowel disease were also examined. Immunoreactive metallothionein (IMT) was found in both rat and human liver localised in the hepatocyte cytoplasm, nucleus, sinusoids and canaliculi. In some livers IMT was found in the portal and hepatic veins. In the small intestine the IMT was localised consistently in the enterocyte cytoplasm and nucleus, and in the basement membrane region. The rat kidney IMT was localised in the cytoplasm of the distal convoluted tubules the collecting tubules and the ducts of Bellini. The distribution of IMT in rat tissues showed changes associated with fasting, stress and zinc administration. In man, inflammatory bowel disease appeared to decrease the intestinal IMT and no significant difference was seen when patients had received steroid therapy. The greatest amounts of IMT were seen in the control group of patients. The distribution of IMT in human liver in Indian childhood cirrhosis did not correspond with that of copper associated protein.

Topics: Animals; Basement Membrane; Cell Nucleus; Crohn Disease; Cytoplasm; Dinitrophenols; Fasting; Histocytochemistry; Humans; Immunoenzyme Techniques; Intestinal Diseases; Intestinal Neoplasms; Intestine, Small; Kidney; Liver; Liver Cirrhosis; Metallothionein; Rats; Tissue Distribution

Topics: Adult; Carcinoma; Cell Compartmentation; Child; Crohn Disease; Humans; Immunoenzyme Techniques; Intestinal Mucosa; Intestine, Small; Liver; Liver Cirrhosis; Metallothionein; Steroids