Original Contribution

The American Journal of Gastroenterology (2005) 100, 1491–1497; doi:10.1111/j.1572-0241.2005.41859.x

The Diurnal Rhythm of the Cytoprotective Human Trefoil Protein TFF2 Is Reduced by Factors Associated with Gastric Mucosal Damage: Ageing, Helicobacter pylori Infection, and Sleep Deprivation

C Emma Johns MD1,5, Julia L Newton PhD3,4, Bruce R Westley PhD1,2 and Felicity E B May DPhil1,2

  1. 1Department of Pathology, University of Newcastle upon Tyne, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne;
  2. 2Northern Institute for Cancer Research, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, UK;
  3. 3Clinical Medical Sciences-Geriatric Medicine, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, UK;
  4. 4Institute for Ageing and Health. University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom;
  5. 5James Cook University Hospital, Marton Road, Middlesbrough, UK

Correspondence: Felicity E B May, Northern Institute for Cancer Research, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, UK

Received 25 November 2004; Revised  0000; Accepted 18 January 2005.

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Abstract

OBJECTIVES:

 

To determine if the normal TFF2 diurnal rhythm is disrupted in those with increased risk of gastric morbidity. Trefoil proteins protect the gastrointestinal mucosa from damage and aid its repair. TFF2 is considered the major cytoprotective gastric trefoil protein. There is a marked circadian variation in gastric luminal TFF2 in young healthy volunteers with peak levels present during the night.

METHODS:

 

Gastric juice was aspirated at two hourly intervals over a 24-h period via a nasogastric tube. TFF2 was measured by quantitative western transfer analysis. Helicobacter pylori (H. pylori) status was measured by C13 urea breath test and by serology. The effects of H. pylori infection, sleep deprivation, and ageing, which cause increased gastric morbidity, on the TFF2 circadian rhythm were tested.

RESULTS:

 

H. pylori infection attenuated the increase in TFF2 that occurs during the night. The TFF2 diurnal rhythm was reduced in older people and both the TFF2 level reached and the time at which the maximum TFF2 concentration occurs were associated inversely with age (p < 0.005). Sleep deprivation delayed the normal night time increase in gastric TFF2 and resulted in an overall reduction in TFF2 secretion.

CONCLUSIONS:

 

H. pylori infection, ageing, and sleep deprivation cause a reduction in the TFF2 diurnal rhythm. The demonstration that the TFF2 rhythm is impaired in cohorts of individuals known to suffer gastric symptoms suggests that interventions to restore the normal TFF2 rhythm in those with poor mucosal protection could reduce morbidity.

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INTRODUCTION

Damage to and Protection of the Gastric Mucosa

Acid and pepsin, together with ingested agents and physical abrasion continually damage the gastric mucosa (1). The mucus:bicarbonate barrier provides the first line of defense for the mucosa, acting both as a physical barrier and by maintaining a pH gradient within the adherent gel layer (1). The second mode of defense is repair of superficial damage to the mucosa by a process called restitution. During restitution, epithelial cells adjacent to the damaged area flatten, extend lamellipodia, and migrate to reform an intact epithelial barrier. Pharmacological agents such as nonsteroidal antiinflammatory drugs (NSAIDs) cause erosion of the mucosa resulting in mucosal hemorrhage and, in severe cases, ulceration. Overt peptic ulceration affects 1 in 10 people during their lifetime (2,3). Shift workers and others with disturbed sleep patterns have an increased incidence of peptic ulcers.

Helicobacter Pylori

The human gastric mucosa is frequently colonized by the gram-negative bacterium Helicobacter pylori (H. pylori) (4). H. pylori colonizes the mucosa within and beneath the adherent mucus layer of the gastric pits (5). In vitro studies have demonstrated that binding to gastric epithelial cells induces intracellular signaling (6) and adherence of H. pylori to epithelial cells induces the production of inflammatory cytokines (7). Gastritis always develops in response to H. pylori infection. Some individuals manifest markedly increased acid secretion that is accompanied by antral predominant or nonatrophic gastritis and duodenal ulceration. Others have a modest increase in acid output with pan gastritis that can progress to gastric atrophy and subsequently to gastric ulceration or cancer. Gastroduodenal disease develops in approx10–20% of infected people (2). Eradication of H. pylori infection is associated with ulcer healing.

Reduced Gastrointestinal Function in Older People

Diseases associated with damage of the gastrointestinal tract such as gastritis, gastric atrophy, peptic ulceration, and gastric cancer increase in prevalence and severity with advancing age (3). Gastrointestinal disease causes considerable morbidity, reduces ability to tolerate medication, and impacts profoundly upon quality of life. Gastric atrophy is accompanied by hypochlorhydia and reduced production of intrinsic factor, which cause inefficient nutrient absorption. Upper gastrointestinal symptoms occur in 40% of older people (8).

Trefoil Proteins are Involved in Protection and Repair of the Gastrointestinal Tract

Trefoil proteins are small, secreted proteins that share homology within a stretch of 42–43 amino acids called the trefoil domain (9,10,11,12). The trefoil domain is characterized by well-conserved features and is stabilized by three disulphide bonds formed between six cysteine residues. There are three human trefoil proteins; TFF1 and TFF3 contain one trefoil domain whereas TFF2 contains two domains and is 106 amino acids in length.

Trefoil proteins are thought to protect the mucosal surfaces in two ways (9,10,11,12). The first is to strengthen the adherent mucus gel layer. TFF1-null mice are devoid of mucus in the gastric antrum (13), and we have shown that human TFF1 is associated with soluble gastric mucins, present in large amounts in adherent mucus (14) and is bound to MUC5AC (15). The second is in stimulating restitution. TFF1 (16,17), TFF2 (18,19), and TFF3 (19) all stimulate the movement of epithelial cells. Experiments in which mice were given recombinant trefoil proteins (16,18) or with transgenic mice (20) have demonstrated that trefoil proteins protect the gastrointestinal tract from damage in vivo. TFF1 dimer is more effective than TFF1 monomer (16) and glycosylated TFF2 is more effective than the nonglycosylated protein (18). Importantly, trefoil proteins prevent (16), and TFF2-null mice are more sensitive to (21), NSAID-induced gastric damage.

TFF2 is considered to be the major cytoprotective trefoil protein (22). Human TFF2 is found in mucus neck cells and in the deeper regions of the gastric glands in the antrum and in Brunner's glands of the duodenum. Significant amounts of 12 kDa TFF2 and much larger quantities of the N-glycosylated form are detected in human gastric juice (23). We have shown previously that there is a dramatic diurnal variation in the gastric luminal concentration of TFF2. Concentrations were lowest in the early evening and rise sharply during the night (24). The increase in TFF2 appears to be due to active secretion of TFF2 as total protein, pepsin, and hydrogen ion concentrations remain constant over 24 h. The timing of the peak in TFF2 levels suggests that the cytoprotective effects of TFF2 occur mainly during sleep. In this context, it is noteworthy that a diurnal rhythm has been observed for hospital admissions due to acute peptic ulcer symptoms with a marked trough in admissions during the night (25). The circadian peak in TFF2 coincides with the trough in acute ulcer presentation (25).

Disruption of the normal TFF2 diurnal rhythm should affect mucosal protection and thereby cause increased gastric morbidity. The effects of H. pylori infection, sleep deprivation, and ageing, all of which cause increased gastric morbidity, were therefore tested on the TFF2 circadian rhythm.

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METHODS

Volunteer Recruitment and Measurement of H. pylori Infection

Volunteers were recruited from the general population and were not attending hospital at the time of the study. All volunteers gave written informed consent. Ethical permission for the study was obtained from the Joint Newcastle Health Hospitals/University of Newcastle upon Tyne Ethical Committee.

To study the effects of H. pylori infection on TFF2 levels, active H. pylori infection was determined by C13 urea breath test ("HP plus," Espire Healthcare Ltd., Rainham, UK). Evidence of previous H. pylori infection was assessed by serology. The levels of IgG against H. pylori were measured by the hospital laboratories in blood taken from the volunteers using the Premier Platinum HpSA ELISA kit (Meridian Diagnostics, Cincinnati, OH). Individuals were classified as H. pylori negative when both tests were negative. Twelve H. pylori negative individuals were recruited for the study on the effects of H. pylori infection on TFF2 levels. The age range of the H. pylori negative individuals was 16–73 yr and the mean age was 38.1 yr. Five H. pylori positive individuals were recruited for the study on the effects of H. pylori infection on TFF2 levels. The age range of the H. pylori positive individuals was 20–69 yr and the mean age was 38.8 yr. H. pylori eradication was deemed to have been successful when the C13 urea test was negative.

Eighteen volunteers were recruited for the study on the effects of age on TFF2 levels. The age range of the volunteers was 16–80 yr and the mean age was 45.8 yr. None of these volunteers was H. pylori positive. Five H. pylori negative individuals were recruited for the study on the effects of sleep deprivation on TFF2 levels. The age range of the individuals was 20–21 yr and the mean age was 20.6 yr.

Collection of Gastric Juice Samples

The volunteers fasted for 12 h prior to initiation of the collection of gastric juice. They attended the observation unit for 26 h. The regimen was designed to resemble the natural situation with normal stimulation of gastric secretion in response to food intake (24). Each individual had a 12F Ryles nasogastric tube (RT 2012, Pennine Healthcare, UK) inserted via the anterior nares without lubrication at 8 A.M. The position of the tube in the dependent part of the stomach was determined by the water recovery method (26). Volunteers drank 20 ml of water that was then recovered by aspiration. Samples of gastric juice were aspirated via the nasogastric tube using a 20-ml sterile syringe at two hourly intervals. The first sample was collected at 9 A.M., 45 min after correct positioning of the tube. A total of 13 samples of gastric juice were collected; the first at 9 A.M. and the last at 9 A.M. the following day. Sleep-deprived volunteers were kept in a light environment, were not permitted to lie down, and were entertained to keep them alert. Gastric juice samples were frozen immediately. The nasogastric tube was removed at 9 A.M. Meals were standardized to ensure comparable intake of protein and were taken at 1 P.M. and 5 P.M., immediately after aspiration of the preceding sample. The volunteers were allowed to drink clear fluids during the 30 min following aspiration of each sample. No alcohol consumption was permitted.

Measurement of TFF2

Aliquots of 1 ml of gastric juice were centrifuged at 10,000 g to remove particulate matter. Aliquots of the supernatant were electrophoresed on polyacrylamide gels that contained 0.1% SDS as described previously (27). The stacking gels contained 10% (w/v) acrylamide, the separating gels contained 20% (w/v) acrylamide, and both contained 10% glycerol. Samples to be fractionated were brought to 62.5 mM Tris HCl pH 6.8, 12.5 mM EDTA, 100 mM beta-mercaptoethanol, and 0.005% bromophenol blue and boiled for 5 min prior to loading. Molecular weight markers and recombinant TFF2 were included in all gels (23,24).

The separated proteins were transferred from the gels to 0.2 mum pore size PVDF membrane (Schleicher and Schuell, Dassel, Germany) and processed for detection of TFF2 as described previously (23,24). The intensities of the TFF2 immuno-reactive protein bands were measured using Labworks 4 software (Ultraviolet Products, Cambridge, UK). The amount of TFF2 protein in the gastric juice samples was determined by comparison with the reaction of standards of known amounts of recombinant TFF2 included on the gel as described previously (24).

The first 9 A.M. sample is affected by the method of positioning of the nasogastric tube (26). This means that samples taken at this time point have an abnormally high pH (24). TFF2 values measured were consistently low at this time point and we have therefore omitted these samples from the analysis. The mean pH of the 11 A.M. samples does not differ significantly from subsequent samples (24). It would have been preferable to collect samples for more than 24 h but this option would have affected recruitment to what is already a demanding regimen.

Statistical Analysis

Individual values were correlated using Pearson's correlation coefficient and differences between groups were tested using the student's t-test. The area under the curve was calculated as a measure of the overall TFF2 concentration during 24 h.

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RESULTS

Helicobacter Pylori Infection Attenuates the Rise in TFF2 Levels

To compare the effect of H. pylori infection on the diurnal rhythm of TFF2, TFF2 was measured in gastric juice collected from volunteers who had never been infected with or who had an active H. pylori infection as described in the methods. Two examples of the results obtained are shown in Figure 1. As reported previously, two forms of TFF2 are detected, the major form is glycosylated TFF2 and the less abundant form is the nonglycosylated protein (23). In samples from a young, 22 yr old, healthy, uninfected individual, a dramatic diurnal rhythm in TFF2 was seen; clearly detectable levels of TFF2 are present at 11 A.M. and are gradually reduced to reach very low levels by 5 p.m. TFF2 levels rose consistently during the night to reach a maximum concentration of 11.8 mug/ml (Fig. 1A). The second young, 20 yr old, healthy but H. pylori positive individual had a clear TFF2 diurnal rhythm, but the amplitude of the rhythm and the maximum levels of TFF2 were lower (Fig. 1B).

Figure 1.
Figure 1 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Detection of gastric luminal TFF2 protein in H. pylori negative (A) and H. pylori positive (B) individuals over 24 h. Human gastric juice was collected from young volunteers at two hourly intervals over a 24-h time course. Aliquots were subjected to electrophoresis on denaturing polyacrylamide gels, transferred to PVDF membrane, and reacted with TFF2 antisera as described in the "Methods" section. The positions of glycosylated TFF2 (gTFF2) and nonglycosylated TFF2 (TFF2) are indicated on the right hand side.

Full figure and legend (59K)

The amounts of TFF2 in the gastric juice samples of 12 uninfected individuals and 5 individuals with an active H. pylori infection were quantified by comparison with known amounts of recombinant TFF2 (24). Mean (SEM) concentrations are shown in Figure 2A. In uninfected individuals, TFF2 levels declined during the day to reach the lowest levels at 5 p.m. and then rose to reach near maximal levels by 3 a.m. Thereafter, TFF2 remained high with the mean level increasing slightly by 9 a.m. The diurnal rhythm of TFF2 in those infected with H. pylori was similar to the rhythm in uninfected individuals between 11 a.m. and 1 a.m. After 1 a.m., the TFF2 level rose but less dramatically and the maximum level reached was lower than in the uninfected group. The TFF2 concentration in those infected with H. pylori was less than half the amount in the uninfected group at 9 a.m.(p= 0.03).

Figure 2.
Figure 2 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author
Figure 2 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Effect of H. pylori infection on the diurnal profile of gastric TFF2. Gastric juice was collected at two hourly intervals for 24 h from 12 H. pylori negative and 5 H. pylori positive individuals and the concentrations of TFF2 were measured as described in the "Methods" section. Mean (SEM) concentrations of TFF2 are shown (A). Mean (SEM) TFF2 at 9 a.m. in H. pylori negative (n = 12) and H. pylori positive individuals (n = 12) and in individuals who have had successful eradication of H. pylori infection (n = 5) are shown (B).

Full figure and legend (20K)

Gastrointestinal symptoms decline in patients after eradication of H. pylori infection. We therefore measured TFF2 in 5 volunteers who had previously been infected with H. pylori and had had successful eradication of the infection. The TFF2 level was intermediate between the levels in the uninfected group and the H. pylori positive group and at 9 a.m., the TFF2 level in the eradicated group was not significantly different from the level in the negative group (Fig. 2B).

The Magnitude of the TFF2 Diurnal Rhythm Decreases with Advancing Age

Individuals over a wide age range were recruited to investigate the effects of advancing age on the TFF2 diurnal rhythm. The results are illustrated after dichotomization above and below the median age of 48 yr as shown in Figure 3. The TFF2 profiles were similar in the two groups from 11 a.m. until 3 a.m. the following day but in the younger group, TFF2 levels continued to rise after 3 a.m. whereas in the older group TFF2 levels were essentially maximal by 3 a.m. and had declined by 9 a.m. This suggests that older people are unable to maintain the production of the high level of gastric TFF2 found in younger people and that therefore both the time at which maximum TFF2 levels occurs and the maximum level attained is altered with ageing.

Figure 3.
Figure 3 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Effect of ageing on gastric luminal TFF2 concentrations over 24 h. Gastric juice was collected at two hourly intervals for 24 h from 18 volunteers and the concentrations of TFF2 were measured as described in the "Methods" section. Mean (SEM) concentrations of TFF2 are shown.

Full figure and legend (14K)

The association between the time at which peak TFF2 levels were reached and age is illustrated in Figure 4. As predicted the time of the TFF2 peak is inversely correlated with age; Pearson's correlation coefficient -0.59, p= 0.002. The association between maximum TFF2 and age is shown in Figure 5. There is a significant inverse correlation; Pearson's correlation coefficient -0.64, p= 0.006.

Figure 4.
Figure 4 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Relationship between the time at which maximum TFF2 levels are reached and age. Gastric juice was collected and TFF2 concentrations in the gastric juice were measured as described in the "Methods" section. The times at which the TFF2 concentration is maximal for each individual are shown plotted against their age.

Full figure and legend (13K)

Figure 5.
Figure 5 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Relationship between maximum TFF2 levels reached and age. Gastric juice was collected and TFF2 concentrations in the gastric juice were measured as described in the "Methods" section. The maximum TFF2 concentrations for each individual are shown plotted against their age.

Full figure and legend (13K)

The TFF2 Diurnal Rhythm is Dependent on Normal Sleep

Highest levels of TFF2 are reached during the night when volunteers are asleep. To investigate if the TFF2 diurnal rhythm is dependent on normal sleep patterns, a group of volunteers were recruited for a study in which they were denied sleep. TFF2 was measured as described in the "Methods" section and the results obtained compared to those for individuals who slept normally (Fig. 6). The two TFF2 diurnal profiles are as expected near identical until after 11 p.m. when the volunteers in the normal sleep pattern arm of the study went to sleep. As shown previously, TFF2 levels rose in the sleeping volunteers to reach maximal levels by 5 a.m. In the sleep-deprived volunteers there was no increase in TFF2 levels by 1 a.m. or 3 a.m. TFF2 was increased in the sleep-deprived volunteers by 5 a.m. but was still 3-fold lower than in the volunteers who were asleep. The amount of secreted TFF2 measured in gastric juice over 24 h was significantly higher in those who slept than in those who did not sleep (p= 0.02). This shows that the normal diurnal rhythm of TFF2 is dependent on sleep.

Figure 6.
Figure 6 - Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Effect of sleep on gastric luminal TFF2 concentrations. Gastric juice was collected from volunteers who slept normally and from 5 volunteers who remained awake during the study. The concentrations of TFF2 were measured as described in the "Methods" section. Mean (SEM) concentrations of TFF2 are shown.

Full figure and legend (19K)

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DISCUSSION

The data presented in this study confirm our previous observation that gastric luminal TFF2 has a dramatic diurnal variation and that the level is at its highest at night during sleep (24). As in the previous study, eating caused a reduction in TFF2 levels. After eating lunch the reduction was up to 19-fold (p= 0.02). We have now shown that the normal TFF2 circadian rhythm is dependent on sleep and not merely concurrent with it. This may contribute to the increased incidence of gastrointestinal symptoms experienced by shift workers and the discomfort felt by others with disturbed sleep patterns such as those traveling between time zones.

H. pylori infection attenuated the nocturnal rise in TFF2 and after successful eradication therapy the TFF2 diurnal rhythm returned to normal. Whether the decrease in TFF2 levels caused by H. pylori infection is a specific regulatory effect or is secondary to gastric atrophy remains to be determined. H. pylori binds specifically to TFF1 in adherent gastric mucus (28), which suggests that H. pylori may exploit the specific concentration of TFF1 in gastric mucus and its binding to MUC5AC (14,15), as a receptor by which to anchor itself in gastric mucus (28). The binding of H. pylori is specific for the TFF1 dimer that is the molecular form that binds MUC5AC (15) and is not observed with the TFF1 monomer (28,27). It is not known if H. pylori interacts with TFF2, but whereas TFF1 colocalizes with H. pylori in mucus secretory cells on the surface of the gastric mucosa and in adherent mucus (28,14,15), TFF2 is reported deeper in the mucus neck cells and antral glands (28,29). In addition, the structures of TFF2 and the TFF1 dimer are remarkably different (30,31,32). Clearly, the interaction of H. pylori with trefoil proteins and the effects of H. pylori infection on trefoil protein expression are an important facet of the pathology of H. pylori infection.

Overall, TFF2 concentrations were reduced in older people and there was an inverse association of maximum TFF2 levels with age. This shows that older people have reduced exposure to the major cytoprotective trefoil protein. The increased incidence of gastric morbidity experienced by older people is well documented but understanding of the underlying causes is poor. The decrease in the TFF2 diurnal rhythm observed with normal ageing provides a potentially important explanation for the clinical observations.

The present study was designed to investigate if factors that are known to reduce effective gastric mucosal protection impact on the TFF2 diurnal rhythm. In all cases the magnitude of the TFF2 rhythm was reduced. This supports the hypothesis that the concentration of TFF2 in the gastric lumen, particularly at night is important for maintenance of a healthy mucosa. If the reduction in TFF2 produced by H. pylori infection, ageing, and sleep disruption could be reversed then the reduction in mucosal protection may be prevented and the occurrence of gastric symptoms avoided. H. pylori infection is usually amenable to eradication therapy but ageing and sleep disruption is unavoidable. Manipulating TFF2 levels either by increasing endogenous expression or by ingestion of exogenous protein may prove a useful intervention in older people, shift workers, or other sleep-deprived people who develop gastric symptoms. Targeting TFF2 levels may also be an effective means to allow more people with arthritis to tolerate the effective NSAIDs that cause gastric damage (33). In this context, it is known that TFF2-deficient mice show increased susceptibility to the effects of damage caused by NSAIDs (21). Such intervention could also have a place in allowing older people to benefit from the cardio- and cerebrovascular protective effects of taking aspirin prophylactically by reducing the associated gastric symptoms (34).

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WHAT IS ACCEPTED AND WHAT THIS RESEARCH ADDS

  • TFF2 is a cytoprotective trefoil protein important in maintenance and repair of the gastric mucosa.
  • There is a dramatic diurnal rhythm in human gastric luminal TFF2 with very high levels present during the night and early morning
  • Reduction in TFF2, particularly at night when gastric mucosal repair is thought to occur, might predispose to increased gastric morbidity
  • Helicobacter pylori infection, sleep deprivation, and advancing age all disrupted the normal TFF2 rhythm.
  • This research demonstrates that there is an attenuation in the TFF2 diurnal rhythm in three cohorts of individuals known to have increased gastric morbidity.
  • Interventions to restore the normal TFF2 rhythm in those with poor mucosal protection could reduce morbidity.
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References

  1. Allen, A, Flemstrom, G. Gastroduodenal mucus bicarbonate barrier: Protection against acid and pepsin. Am J Physiol Cell Physiol 2005;288: C1–C19. | PubMed | ChemPort |
  2. Blaser, MJ. The role of Helicobacter pylori in gastritis and its progression to peptic ulcer disease. Aliment Pharmacol Ther 1995;9: 27–30.
  3. Rockall, T, Logan, RFA, Devlin, HB. Incidence of and mortality from acute upper gastrointestinal haemorrhage in the United Kingdom. Steering Committee and members of the National Audit of Acute Upper Gastrointestinal Haemorrhage. BMJ 1995;311: 222–226. | PubMed | ChemPort |
  4. Marshall, BJ, Warren, JR. Unidentified curved bacilli in the stomach of patients with gastritis and peptic ulceration. Lancet 1984;i: 1311–1315.
  5. Hazell, SL, Lee, A, Brady, L, Hennessy, W. Campylobacter pyloridis and gastritis: Association with intercellular spaces and adaptation to an environment of mucus as important factors in colonization of the gastric epithelium. J Infect Dis 1986;153: 658–663. | PubMed | ChemPort |
  6. Odenbreit, S, Puls, J, Sedlmaier, B, et al. Translocation of Helicobacter pylori CagA into gastric epithelial cells by type IV secretion. Science 2000;287: 1497–1500. | Article | PubMed | ISI | ChemPort |
  7. Rieder, G, Hatz, RA, Moran, AP, et al. Role of adherence in interleukin-8 induction in Helicobacter pylori-associated gastritis. Infect Immun 1997;65: 3622–3630.
  8. Kay, L. Prevalence, incidence and prognosis of gastrointestinal symptoms in a random sample of an elderly population. Age Ageing 1994;94: 146–9.
  9. Poulsom, R, Wright, NA. Trefoil peptides: A newly recognized family of epithelial mucin-associated molecules. Am J Physiol 1993;265: G205–13. | PubMed | ISI | ChemPort |
  10. May, FEB, Westley, BR. Trefoil proteins: Their role in normal and malignant cells. J Pathol 1997;183: 4–7.
  11. Thim, L. Trefoil peptides: From structure to function. Cell Mol Life Sci 1997;53: 888–903. | Article | PubMed | ChemPort |
  12. Taupin, D, Podolsky, DK. Trefoil factors: Initiators of mucosal healing. Nat Rev Mol Cell Biol 2003;4: 721–32. | Article | PubMed | ChemPort |
  13. Lefebvre, O, Chenard, MP, Masson, R, et al. Gastric mucosa abnormalities and tumorigenesis in mice lacking the pS2 trefoil protein. Science 1996;274: 259–62. | Article | PubMed | ISI | ChemPort |
  14. Newton, JL, Allen, A, Westley, BR, et al. The human trefoil peptide, TFF1, is present in different molecular forms that are intimately associated with mucus in normal stomach. Gut 2000;46: 312–20. | Article | PubMed | ChemPort |
  15. Ruchaud-Sparagano, MH, Westley, BR, May, FEB. The trefoil protein TFF1 is bound to MUC5AC in human gastric mucosa. Cell Mol Life Sci 2004;61: 1946–54.
  16. Marchbank, T, Westley, BR, May, FEB, et al. Dimerization of human pS2 (TFF1) plays a key role in its protective/healing effects. J Pathol 1998;185: 153–8. | Article | PubMed | ISI | ChemPort |
  17. Prest, SJ, May, FEB, Westley, BR. The estrogen-regulated protein, TFF1, stimulates migration of human breast cancer cells. FASEB J 2002;16: 592–4. | PubMed | ChemPort |
  18. Playford, RJ, Marchbank, T, Chinery, R, et al. Human spasmolytic polypeptide is a cytoprotective agent that stimulates cell migration. Gastroenterology 1995;108: 108–16. | Article | PubMed | ISI | ChemPort |
  19. Dignass, AU, Lynch-Devaney, K, Kindon, H, et al. Trefoil peptides promote epithelial migration through a transforming growth factor beta-independent pathway. J Clin Invest 1994;94: 376–83. | Article | PubMed | ISI | ChemPort |
  20. Playford, RJ, Marchbank, T, Goodlad, RA, et al. Transgenic mice that overexpress the human trefoil peptide pS2 have an increased resistance to intestinal damage. Proc Natl Acad Sci USA 1996;93: 2137–42. | Article | PubMed | ChemPort |
  21. Farrell, JJ, Taupin, D, Koh, TJ, et al. TFF2/SP-deficient mice show decreased gastric proliferation, increased acid secretion, and increased susceptibility to NSAID injury. J Clin Invest 2002;109: 193–204. | Article | PubMed | ISI | ChemPort |
  22. Alison, MR, Chinery, R, Poulsom, R, et al. Experimental ulceration leads to sequential expression of spasmolytic polypeptide, intestinal trefoil factor, epidermal growth factor, and transforming growth factor alpha mRNAs in rat stomach. J Pathol 1995;175: 405–14. | Article | PubMed | ISI | ChemPort |
  23. May, FEB, Semple, JI, Newton, JL, et al. The human two domain trefoil protein, TFF2, is glycosylated in vivo in the stomach. Gut 2000;46: 454–9.
  24. Semple, JI, Newton, JL, Westley, BR, et al. Dramatic diurnal variation in the concentration of the human trefoil peptide TFF2 in gastric juice. Gut 2001;48: 648–55.
  25. Svanes, C, Sothern, RB, Sørbye, H. Rhythmic patterns in incidence of peptic ulcer perforation over 5.5 decades in Norway. Chronobiol Int 1998;15: 241–64.
  26. Baron, JH. History, methodology and interpretation. Clinical tests of gastric secretion. Macmillan: London, 1978.
  27. Chadwick, MP, Westley, BR, May, FEB. Homodimerization and hetero-oligomerization of the single-domain trefoil protein pNR-2/pS2 through cysteine 58. Biochem J 1997;327: 117–23. | PubMed | ISI | ChemPort |
  28. Clyne, M, Dillon, P, Daly, S, et al. Helicobacter pylori interacts with the human single-domain trefoil protein TFF1. Proc Natl Acad Sci USA 2004;101: 7409–14.
  29. Longman, RJ, Douthwaite, J, Sylvester, PA, et al. Coordinated localisation of mucins and trefoil peptides in the ulcer associated cell lineage and the gastrointestinal mucosa. Gut 2000;47: 792–800. | Article | PubMed | ISI | ChemPort |
  30. Gajhede, M, Petersen, TN, Henriksen, A, et al. Pancreatic spasmolytic polypeptide: First three-dimensional structure of a member of the mammalian trefoil family of peptides. Structure 1993;1: 253–62.
  31. Williams, MA, Westley, BR, May, FEB, et al. The solution structure of the disulphide-linked homodimer of the human trefoil protein TFF1. Pancreatic spasmolytic polypeptide: First three-dimensional structure of a member of the mammalian trefoil family of peptides. FEBS Lett 2001;493: 70–4.
  32. Muskett, FW, May, FEB, Westley, BR, et al. Solution structure of the disulfide-linked dimer of human intestinal trefoil factor (TFF3): The intermolecular orientation and interactions are markedly different from those of other dimeric trefoil proteins. Biochemistry 2003;42: 15139–47.
  33. Somerville, K, Faulkner, G, Langman, M. Non-steroidal anti-inflammatory drugs and bleeding peptic ulcer. Lancet 1986;1(8479):462–4.
  34. Newton, JL, Johns, CE, May, FEB. Review article: The ageing bowel and intolerance to aspirin. Aliment Pharmacol Ther 2004;19: 39–45.
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Acknowledgements

C. Emma Johns was the recipient of a training fellowship funded jointly by Research into Ageing and the Digestive Diseases Foundation. This work was supported by the Newcastle University Hospitals' Special Trustees, the Wellcome Trust and Cancer Research, UK.

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