Helicobacter pylori infection stimulates intestinalization of endocrine cells in glandular stomach of Mongolian gerbils

Abstract

Intestinal metaplasia has been investigated extensively as a possible premalignant condition for stomach cancer but its pathogenesis is still not fully understood. In the present study, we examined the relationship between endocrine and mucous cell marker expression periodically after Helicobacter pylori infection in the Mongolian gerbil model. The numbers of chromogranin A (CgA)-positive, gastrin-positive and gastric inhibitory polypeptide (GIP)-positive cells in H. pylori-infected groups was increased significantly compared with the non-infected case. However, CgA-positive and gastrin-positive cells then decreased from 50 through 100 experimental weeks after H. pylori infection, whereas GIP-positive cells increased. Coexistence of gastrin-positive and GIP-positive cells was detected in the same gastric and intestinal mixed phenotypic glandular-type glands. In conclusion, the endocrine cell phenotype is in line with that of the mucous counterpart in the glands of H. pylori-infected Mongolian gerbil stomach, supporting the concept that development of intestinal metaplasia is due to the abnormal differentiation of a stem cell.

Figure 1

Experimental design. Hp, Helicobacter pylori.

Figure 2

The average numbers (mean ± SD) of (A) glandular (G)‐type, (B) gastric and intestinal mixed (GI)‐type and (C) intestinal (I)‐type glandular ducts in Hp(–)‐50‐week (n = 8), Hp(+)‐50‐week (n = 10), Hp(+)‐75‐week (n = 6), and Hp(+)‐100‐week (n = 9) cases. *P < 0.05, **P < 0.005 vs the average Hp(–)‐50‐week number.

Figure 3

Immunohistochemical staining of chromogranin A (CgA), gastrin and gastric inhibitory polypeptide (GIP) in (A–D) normal fundic and (E–H) pyloric regions, (I–L) duodenum, (M–P) small intestines and (R–U) large intestines of Mongolian gerbils. Expression of CgA was observed in the bottom of (B) normal fundic, (F) pyloric, (J) duodenal, (N) small intestinal and (S) colonic glandular ducts. (C,D) No gastrin or GIP was observed in the fundic glands. In the pyloric glands, (G) expression of gastrin was detected clearly, but (H) no GIP expression was observed. In the duodenum and small intestine, (L,P) GIP expression was detected, but (K,O) no gastrin expression was observed. Neither (T) gastrin nor (U) GIP were detected in the large intestine. Original magnification: (A) ×100; (B–U) ×400.

Figure 4

Immunohistochemical analysis of chromogranin A (CgA)‐, gastrin‐ and gastric inhibitory polypeptide (GIP)‐positive cells. (A) Normal gastrointestinal tract. (B) Helicobacter pylori‐infected Mongolian gerbils. *P < 0.01, **P < 0.005, ***P < 0.0005 compared with each control group.

Figure 5

Real‐time reverse transcription–polymerase chain reaction analysis of chromogranin A (CgA), gastrin and gastric inhibitory polypeptide (GIP) in the pyloric region of Mongolian gerbils. (A) Normal alimentary tract. (B) Isolated pyloric glands from Helicobacter pylori‐infected stomachs.

Figure 6

Expression of gastrin and gastric inhibitory polypeptide (GIP) in (A) glandular (G)‐type, (B) gastric and intestinal mixed (GI)‐type and (C) intestinal (I)‐type glands. (A) In the G‐type glands, gastrin‐positive cells were identified by brown cytoplasmic staining (red arrow), but no GIP expression was observed. (B) In the GI‐type glands, gastrin‐ and GIP‐positive cells were identified by brown (red arrow) and dark purple (blue arrow) cytoplasmic staining. (C) In the I‐type glands, GIP expression was detected by dark purple staining (blue arrow), but no gastrin expression was apparent. Original magnification: (A–C) ×500.

Figure 7

Expression of gastrin and gastric inhibitory polypeptide (GIP) in glandular (G)‐type, gastric and intestinal mixed (GI)‐type and intestinal (I)‐type glands. The number of gastrin‐positive cells decreased gradually from G‐type through GI‐type to I‐type glands (P < 0.0001), correlating inversely with the number of GIP‐positive cells (P < 0.0001).