Cơ chế dẫn đến loét nào sau đây không do Hélicobacter pylori gây ra:

Helicobacter pylori (H. pylori) causes duodenal ulcers through several mechanisms: * **Metaplasia of the duodenal mucosa:** H. pylori causes inflammation, leading to gastric metaplasia in the duodenum, creating conditions for acid to attack the duodenal mucosa, causing ulcers. * **Inhibition of H+ feedback mechanism:** H. pylori reduces the number of D cells (secreting somatostatin) in the antrum. Somatostatin inhibits G cells (secreting gastrin). Therefore, H. pylori indirectly increases gastrin and acid secretion. * **Facilitating H+ back diffusion:** H. pylori damages the mucosal barrier, creating conditions for H+ to back diffuse into the mucosa, causing damage. * **Prolonged increase in blood gastrin increases acid secretion:** H. pylori causes inflammation of the gastric antrum, reducing the number of D cells (secreting somatostatin). Somatostatin inhibits G cells (secreting gastrin). Therefore, H. pylori indirectly increases gastrin and acid secretion. However, the *prolonged increase in blood gastrin* is not the *only* mechanism caused by H. pylori, but also due to many other factors. Therefore, the correct answer is: Prolonged increase in blood gastrin increases acid secretion.