Do infiltrating leukocytes contribute to the adaptation of human gastric mucosa to continued aspirin administration?

Insights into the mechanisms of gastric adaptation to aspirin-induced injury: a role for regenerating protein but not trefoil peptides

The phenomenon of reduced gastric mucosal injury despite repeated doses of a damaging agent is termed adaptation. Adaptation to nonsteroidal anti-inflammatory drug-induced injury has been clearly demonstrated in both humans and experimental animals; however, the precise mechanisms remain unclear. We hypothesized that mediators of adaptation might be the regenerating protein (RegI) and the trefoil peptides TFF1 and TFF2, because these proteins play pivotal roles in gastric mucosal protection and repair. The gene expression and the protein levels of these proteins were measured and compared in normal, aspirin-injured, and aspirin-adapted rat stomachs. TFF gene and protein expression levels were similar in all three groups, whereas RegI gene expression and protein levels in adapted stomach were increased. A time course analysis of RegI expression during the onset and offset of adaptation showed that mucosal RegI increased during the development of adaptation, was maintained during subsequent aspirin dosing, and returned to baseline levels once dosing had ceased and adaptation was lost-indicative of a causal role in the adaptation process. Colocalization of increased RegI with gastric epithelial areas showing increased proliferation also suggests that RegI may be an important mediator of the resolution of mucosal injury that is characteristic of gastric adaptation to aspirin.

Resistance to apoptosis is a mechanism of adaptation of rat stomach to aspirin

Adaptation of the gastric mucosa to nonsteroidal anti-inflammatory drug-induced injury is a well-documented phenomenon, but the mechanisms are not known. We investigated whether changes in stress protein expression and apoptosis play roles in adaptation of rat stomach to aspirin. RT-PCR and Western blotting techniques were used to analyze mRNA and protein expression of HSP72 and HSP90 and cleavage of caspase 3 protein. Apoptosis was detected by the TUNEL method and quantified. HSP72 mRNA and protein expression was unchanged in adapted mucosa, whereas HSP90 mRNA and protein levels decreased. Caspase 3 protein was activated, and the number of apoptotic cells increased in mucosa after one aspirin dose. However, in adapted mucosa after aspirin, activated caspase 3 and the number of apoptotic cells had returned to basal levels. Induction of the stress response was found not to be a mechanism of mucosal adaptation against multiple doses of aspirin. Our results lead us to propose instead that resistance to aspirin-induced apoptosis plays a role in the protective phenomenon of adaptation.

Rebamipide prevents occurrence of gastric lesions following transcatheter arterial embolization in the hepatic artery

BACKGROUND

Transcatheter arterial embolization (TAE) of the hepatic artery is a common treatment method for hepatocellular carcinoma (HCC), but it often induces gastric mucosal injury. We examined whether or not rebamipide administration, beginning 1 week before and ending 2 weeks afterTAE, can prevent worsening of gastric mucosal disorders.

METHODS

The subjects were 73 chronic hepatitis C or type C liver cirrhosis patients who concomitantly had HCC and received TAE in our hospital. The patients were randomly allocated to the rebamipide group (oral, 300 mg/day for 3 weeks starting 1 week before TAE) or the non-rebamipide group. Gastric endoscopy was performed 1 week before and 2 weeks afterTAE and the presence of erythema, erosion and/or submucosal haemorrhagic spots was monitored. Based on the findings, gastric mucosal disorder before and after TAE was quantitatively evaluated using the modified Lanza score (MLS).

RESULTS

Overall, MLS after TAE increased significantly (P< 0.05). However, in the rebamipide group, MLS did not change. The MLS after TAE increased significantly in patients who had either liver cirrhosis, oesophageal varices or gastropathy (P< 0.01 or < 0.05). In the non-rebamipide group, a significant increase in MLS after TAE was observed in patients who had one of the above-mentioned three diseases (P< 0.01 or < 0.05).

CONCLUSIONS

Gastric lesions which were present before TAE were significantly worsened after TAE. Rebamipide administration prevents TAE-induced aggravation of gastric lesions.

Aspirin-induced gastritis, like Helicobacter pylori-induced gastritis disinhibits acid secretion in humans: relation to cytokine expression

BACKGROUND

Helicobacter pylori infection contributes to hypergastrinemia and hypersecretion of acid by blocking inhibitory reflex pathways to gastrin and parietal cells normally activated by antral distention. Our aim was to investigate whether a similar blockade of inhibitory responses could be provoked by inducing gastritis with aspirin, thus implicating a common inflammatory component, possibly a proinflammatory cytokine(s).

METHODS

We studied the effects of antral distention on stimulated acid secretion and gastrin release in H. pylori-negative volunteers, before and after 3 days of aspirin therapy (2 g daily). Immediately before the examinations, the severity of gastric mucosal injury was evaluated macroscopically and histologically, and the production of interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor (TNF)-alpha, and interferon (IFN)-gamma was determined by immunohistochemistry.

RESULTS

Most subjects had severe gastric injury after aspirin therapy, resulting in a substantially increased production of IL-1beta, IL-6, and IL-8 but not of TNF-alpha and IFN-gamma in the antral mucosa. In these subjects the acid-inhibitory response was abolished or markedly reduced. Conversely, aspirin therapy failed to affect the gastrin release in all subjects studied.

CONCLUSIONS

The disinhibition of acid secretion in response to antral distention is a joint feature of the gastritis induced by aspirin and H. pylori infection, possibly related to the increased production of IL-1beta, IL-6, and IL-8. The H. pylori-related hypergastrinemia apparently has a different background.

Growth markers in the human gastric mucosa during adaptation to continued aspirin administration

The mechanism of gastric mucosal adaptation to continued aspirin (ASA) administration is unknown. We have investigated growth and proliferation markers in healthy subjects under prolonged ASA treatment. In eight healthy volunteers, ASA treatment (2 g/day) was continued for 14 days. Endoscopy was performed before medication; at days 3, 7, and 14 of ASA treatment; and at days 16 and 18 (2 and 4 days, respectively, after medication was ceased). Gastric biopsies from oxyntic and antral mucosa were studied by histology and by histochemistry for proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGFr). ASA treatment did not change the expression of EGF and EGFr significantly. The PCNA index showed local inconsistent variations. However, increased TGF-alpha expression after ASA was noted, particularly in hyperplastic surface epithelium. Edema and teleangiectases were common in gastric mucosa after ASA. An increasing incidence of foveolar hyperplasia was also noted in the antral mucosa. Healthy subjects on prolonged ASA treatment gradually develop parameters of chronic reactive gastritis accompanied by increased TGF-alpha expression in gastric surface epithelial cells, especially in hyperplastic areas.