Brian T. Cooper

A role for iron in Wnt signalling

There is an emerging body of evidence implicating iron in carcinogenesis and in particular colorectal cancer, but whether this involves Wnt signalling, a major oncogenic signalling pathway has not been studied. We aimed to determine the effect of iron loading on Wnt signalling using mutant APC (Caco-2 and SW480) and wild-type APC (HEK-293 and human primary fibroblasts) containing cell lines. Elevating cellular iron levels in Caco-2 and SW480 cells caused increased Wnt signalling as indicated by increased TOPFLASH reporter activity, increased mRNA expression of two known targets, c-myc and Nkd1, and increased cellular proliferation. In contrast wild-type APC and β-catenin-containing lines, HEK 293 and human primary fibroblasts were not responsive to iron loading. This was verified in SW480 cells that no longer induced iron-mediated Wnt signalling when transfected with wild-type APC. The cell line LS174T, wild type for APC but mutant for β-catenin, was also responsive suggesting that the role of iron is to regulate β-catenin. Furthermore, we show that E-cadherin status has no influence on iron-mediated Wnt signalling. We thus speculate that excess iron could exacerbate tumorigenesis in the background of APC loss, a common finding in cancers.

A role for tumour necrosis factor α in human small bowel iron transport

Cytokines are integral to the development of anaemia of chronic inflammation. Cytokines modulate hepcidin expression and iron sequestration by the reticuloendothelial system but their direct effects on small bowel iron transport are not well characterized. The aim of the present study was to examine the local effects of TNFalpha (tumour necrosis factor alpha) on small bowel iron transport and on iron transporter expression in the absence of hepcidin. The effects of TNFalpha on iron transport were determined using radiolabelled iron in an established Caco-2 cell model. The effect of TNFalpha on the expression and localization of the enterocyte iron transporters DMT-1 (divalent metal transporter 1), IREG-1 (iron-regulated transporter 1) and ferritin was determined utilizing Caco-2 cells and in a human ex vivo small bowel culture system. TNFalpha mediated an early induction in both iron import and iron export, which were associated with increased DMT-1 and IREG-1 mRNA and protein expression (P<0.05). However, by 24 h, both iron import and iron export were significantly inhibited, coinciding with an induction of ferritin heavy chain (P<0.05) and a decrease in DMT-1 and IREG-1 to baseline levels. In addition, there was a relocalization of IREG-1 away from the basolateral cell border and increased iron deposition in villous enterocytes. In conclusion, TNFalpha has a direct effect on small bowel iron transporter expression and function, leading to an inhibition of iron transport.

An analytical method for the quantitation of mannitol and disaccharides in serum: a potentially useful technique in measuring small intestinal permeability in vivo

An electrochemical-HPLC method for the determination of mannitol and lactulose is presented which may facilitate routine testing of intestinal permeability by requiring only a single blood sample instead of a 6-hour urine collection. Chromatographic conditions are described which allow separation of the closely related sugars lactulose and the dietary disaccharides lactose and sucrose. Preliminary results in normal controls and patients with untreated coeliac disease are presented.

The Emerging Role of the Liver in Iron Metabolism

Iron is essential in health and well-being and its dysregulation is a common theme in disease. Recent advances in our understanding of the molecular biology underlying hemochromatosis and anemia has provided insight into the complex mechanisms implicated in iron metabolism. The proximal small bowel is the major site of iron absorption and, it is becoming increasingly clear that the regulation of this process involves the liver and, in particular, the hepatic antimicrobial peptide hepcidin. A number of studies have shown hepcidin to have an inhibitory function at the level of small bowel iron absorption, although its exact site of action remains to be elucidated. Clearly, identifying the target of hepcidin is of importance and is likely to lead to the development of therapeutic agents in the treatment of iron disorders.

Barrett's oesophagus: an audit of surveillance over a 17-year period.

Objective To audit whether our patients with Barretts oesophagus (BO) enter into our endoscopic surveillance programme and whether they continue with it after entry. We have determined the incidence of oesophageal adenocarcinoma among our surveyed patients. Design We retrospectively audited prospectively collected data from our BO surveillance programme over the years 1987–2003. Setting An inner city teaching hospital. Results During these years, 466 patients with BO were diagnosed (392 long segment, ≥3 cm), 29 had oesophageal adenocarcinoma at diagnosis, 232 [195 with intestinal metaplasia (IM) on biopsy] had at least one follow-up endoscopy, and 205 have not been re-endoscoped. In 27 out of 205 no IM was present. Of the remaining 178 out of 205 with IM, 30 were within 2 years of diagnosis and 148 have not been re-endoscoped for the following reasons: age (51), non-attendance (35), not referred back by general practitioner (30), non-oesophageal cancer (14), severe concurrent illness (12), death (three), refused follow-up (two), left the area (one). The 195 patients with IM who entered endoscopic surveillance consisted of 108 men and 87 women (aged 62.9 years, range 31–96), were followed for a total of 1068 patient-years (average 5.5 years), and had 556 endoscopies (average 2.9 per patient). Ninety-seven out of 195 patients remain under active endoscopic surveillance but 98 discontinued for the following reasons: age (31), non attendance (21), death (21 including one from oesophageal adenocarcinoma), refused follow up (seven), concurrent illness (six), left the area (four), no IM on repeat biopsies (three). Of the 195 patients with IM, four developed low-grade dysplasia, two high-grade dysplasia and four adenocarcinoma (incidence 0.37%); 178 out of 195 have been maintained on proton pump inhibitor (PPI) therapy. Conclusions The majority of patients with BO either do not enter or do not continue in an endoscopic surveillance programme. This needs to be acknowledged when the workload and cost of BO surveillance programmes are considered. The incidence of adenocarcinoma was low compared with many published series, and we speculate whether this is the result of maintenance PPI therapy.

Outcome of Surgical Fundoplication for Extraesophageal (Atypical) Manifestations of Gastroesophageal Reflux Disease in Adults: A Systematic Review

BACKGROUND A significant proportion of patients with gastroesophageal reflux disease (GERD) present with atypical symptoms (extraesophageal reflux; EER). The effectiveness of surgical fundoplication in treating classical reflux symptoms is well documented, but the role of surgery in alleviating EER symptoms is less clear. The aim of this study was to review the published literature to determine whether surgical fundoplication is effective in controlling EER. MATERIALS AND METHODS A Medline, PubMed, and Cochrane database search was done to find articles on surgery for extraesophageal reflux (1991-2006). Articles on pediatric patients were excluded. The parameters looked at were patient selection, resolution of symptoms, change in the quality of life, and any adverse outcomes. RESULTS In 25 studies, a variable proportion (15-95%) of patients with various symptoms of EOR improved after surgical fundoplication. The percentage of patients with EER responding to surgery was less than that reported for classical GERD. CONCLUSIONS The majority of patients in most studies seem to improve symptomatically after surgery. However, a small percentage remains unchanged or worsens. The reported studies are so disparate in their methodology that firm conclusions on the role of surgery are difficult. Further studies are needed. These should be large, multicenter, prospective trials comparing medical and surgical treatment with standardized diagnostic criteria for EER. Pre- and post-treatment assessment, the type of surgery performed, and follow-up should be standardized.

Ethnic differences in gastro-oesophageal reflux disease.

OBJECTIVES To see whether the anecdotal statement that gastro-oesophageal reflux disease is less common in blacks than in white Caucasians is true. DESIGN Study of the racial origin of adult patients who, at endoscopy, have oesophageal damage due to gastro-oesophageal reflux. SETTING Gastroenterology unit of a teaching hospital in inner city Birmingham, UK. MAIN OUTCOME MEASURE Ethnicity and endoscopic grade of oesophageal damage (reflux oesophagitis) were recorded in every patient in whom oesophageal damage due to gastro-oesophageal reflux was diagnosed. RESULTS Over the eight-year period 1989-1996, 1101 patients with endoscopically diagnosed grades I-V reflux oesophagitis have been seen, of whom 893 (81.9%) were white, 156 (14%) were Indian and 52 (5%) were Afro-Caribbeans. There were fewer patients with reflux oesophagitis from the two non-white ethnic groups than would be expected from their prevalence in the catchment population, and severe reflux oesophagitis was less common than expected in the two non-white groups. In all groups, patients with grades III, IV and V reflux oesophagitis were older than patients with grades I and II disease. Whites tended to be older than Afro-Caribbeans or Indians. CONCLUSION There were fewer non-whites with reflux oesophagitis than would be expected but the reasons for this are unclear. This study has been useful as a pilot but further studies are needed in ethnically mixed non-migrant populations both in hospital, primary care and the community to clarify racial differences in reflux oesophagitis.

Coeliac disease in South Asians resident in Britain: comparison with white Caucasian coeliac patients

Background The catchment population of our hospital is ethnically diverse and we have seen a number of patients of South Asian origin with coeliac disease. We have suspected that there are differences compared with white Caucasian coeliacs, especially with respect to iron-deficiency anaemia and vitamin D deficiency at presentation. Aims To compare the clinical and laboratory features of South Asian adult coeliac patients with adult white Caucasian coeliacs. Methods We reviewed the notes of patients attending the adult coeliac clinic over the past 10 years. All patients were older than 16 years at diagnosis. There were 40 South Asians and 90 white Caucasians. Symptoms, haematology, biochemistry, endomysial antibody status, HLA alleles and small bowel histology at presentation were compared between the two racial groups. Results There were significant differences between the racial groups. South Asians were younger at presentation than the Caucasian patients (mean age 27 years compared with 47 years respectively, P<0.0001); they were less likely to have ‘irritable bowel syndrome’ symptoms (P<0.01), but more likely to have features of vitamin D deficiency (P<0.03). Their haemoglobin (P<0.05), mean cell volume (P<0.0004), serum iron (P<0.01), transferrin saturation (P<0.05), serum 1,25-dihydroxyvitamin D3 (P<0.002), and levels were lower, while serum alkaline phosphatase levels were higher (P<0.04) than in white Caucasian coeliac patients. There were no differences with respect to serum folate, vitamin B12, serum calcium, alanine aminotransferase and small bowel histology. IgA class endomysial antibody positivity was similar in the two groups (88.5% for South Asians compared with 73.5% for white Caucasians). White Caucasian patients were significantly more likely to be DQ2-positive than the South Asian patients (97.2% compared with 83.3%, P=0.02). Conclusion South Asians with coeliac disease are less likely to present with ‘irritable bowel syndrome’ symptoms, but more likely to have features of vitamin D deficiency and iron deficiency, and have a higher alkaline phosphatase than white Caucasians. The differences in HLA alleles seen in South Asians with coeliac disease compared with white Caucasian patients suggests that among the South Asians, non-HLA regions may play a stronger role in disease susceptibility and presentation.

Differential ferritin expression is associated with iron deficiency in coeliac disease.

Background Sixty percent of people with coeliac disease (CD) are iron deficient. Many, however, remain iron replete despite the disease. Aims (i) To characterize the changes in duodenal iron transport proteins in CD with and without iron deficiency. (ii) To examine if iron-activated gut lymphocytes can inhibit iron export in an enterocyte cell model. Methods Endoscopic duodenal biopsies were collected from patients with normal duodenum with and without iron deficiency anaemia and untreated CD sufferers with iron deficiency (n=10 each group). mRNA expression of iron transport proteins was determined by quantitative real time PCR. Protein localization and expression was determined from histology sections in patients with normal duodenum (n=20), and patients with untreated CD with and without iron deficiency (n=20). In addition, CaCo2 cells were cocultured with iron-activated lymphocytes 55Fe was used to determine the effect on CaCo2 cell iron transport. Results The expression of divalent metal transporter 1 and ferroportin was increased in CD with or without iron deficiency. Ferritin expression was increased in CD but only in those with associated iron deficiency. TNF-&agr; produced by activated lymphocytes inhibited iron export from CaCo2 cells. Conclusion Increased enterocyte ferritin expression may promote iron deficiency in CD and this effect seems to be dependent upon TNF-&agr; expression in gut lymphocytes.

Small intestinal lactase status, frequency distribution of enzyme activity and milk intake in a multi-ethnic population

The aims of the study were to investigate the prevalence of primary lactase deficiency, frequency distribution of lactase activity and the relationship between lactose intake and lactase activity in three ethnic groups resident in Birmingham. Seventy-two white, 103 Indian and 58 Afro-Caribbean adult dyspeptic patients had distal duodenal biopsies taken for disaccharidase assay at endoscopy. Ten percent of whites, 51% Indians and 81% Afro-Caribbeans had primary lactase deficiency (sucrase/lactase ratio > 4). There was a generalized unexplained depression of disaccharidase activities in the Indians. Frequency distribution of lactase activity for the whole population showed a negative skew without evidence of trimodality. Lactose intake and symptoms attributed to lactose were assessed in a subgroup of 20 whites, 20 Indians and 18 Afro-Caribbeans by questionnaire. Lactose intake did not differ between lactase persistent and deficient subjects both within each racial group and between the groups. Diarrhoea, bloating and cramps were not significantly more common in lactase deficient than lactase persistent individuals.