Abstract
A close association has been established between climate and peptic ulcer bleeding (PUB). The incidence of PUB in cold climates is significantly higher than that in hot climates. In this study, gastric mucosal damage and its barrier function (through associated barrier factors) in extreme climate conditions were examined to investigate the pathogenesis of PUB in extreme cold climates. Gastric juice and biopsy specimens were collected from 176 patients with peptic ulcer. Conventional hematoxylin and eosin staining was used to exclude malignant ulcers. Helicobacter pylori infections were detected by modified Giemsa staining. pH values of the gastric juice samples were obtained on-site by precise pH dipstick readings. The protein expression levels of heat shock protein (HSP) 70, occludin, nitric oxide synthase (NOS), epidermal growth factor (EGF) and EGF receptor (EGFR) in the gastric mucosa were detected by immunohistochemistry. No significant differences were identified between the high and low bleeding risk groups in the rates of H. pylori infection and the pH values of the gastric juices in the extreme hot or cold climates. Furthermore, no statistically significant differences were identified in the protein expression levels of occludin, NOS, EGF and EGFR between the high and low bleeding risk groups. In the extreme cold climate, the expression of HSP70 and the mucus thickness of the gastric antrum in the high bleeding risk group were significantly lower than those in the low bleeding risk group. The protein expression levels of occludin, HSP70, NOS and EGFR in the extreme cold climate were significantly lower than those in the extreme hot climate, whereas the gastric acid secretion was significantly higher in the extreme cold climate than that in the extreme hot climate. In conclusion, low expression of HSP70 in the gastric mucosa and reduced gastric mucus thickness may play key roles in the mechanism of PUB in extreme cold climates. The significant decrease in barrier factors and increase in damage in extreme cold climates may be associated with the seasonal pattern of peptic ulcers.
Highlights
In recent years, meteorological disasters, including droughts and severe winter weather, have occurred frequently in the world
The pH value of the gastric juice was lower in the high bleeding risk group (1.93±1.04) than that in the low bleeding risk group (2.05±1.27) in the extreme hot climate, but the difference was not statistically significant. This was consistent with the results for the extreme cold climate, in which no significant difference was identified in the pH values of the gastric juice between the high (1.00±0.81) and low (1.35±0.93) bleeding risk groups (Table II)
Peptic ulcers are caused by defects in the gastro‐duodenal mucosal barrier that result from epithelial cell damage, which is evoked by caustic agents, including gastric acid and pepsin [4]
Summary
Meteorological disasters, including droughts and severe winter weather, have occurred frequently in the world. Extreme climates seriously affect health and have resulted in the increased morbidity of a number of diseases, including gastrointestinal bleeding [1], which exhibit a higher frequency in the winter than in the summer. Peptic ulcer bleeding (PUB) is the most common cause of upper gastrointestinal bleeding, including gastric ulcers (GU) and duodenal ulcers(DU). Certain studies have indicated that the incidence of peptic ulcers in cold climates is significantly higher than that in hot climates [2,3]. Cold climate and rapid climate change may induce PUB [2,3], but little is known regarding its specific pathogenesis. Gastric mucosal damage and barrier factors were examined in extreme climates to clarify the pathogenesis of PUB under extreme climate conditions
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