IL-11 is a parietal cell cytokine that induces atrophic gastritis

Abstract

Background and aims: IL-is important in gastric damage, mucosal repair and gastric cancer progression. We analysed IL-11 expression in H.pylori infected mouse stomach, the site of gastric IL-11 expression in mice and humans, and the effect of exogenous IL-11 on gastric mucosal homeostasis.

Methods: IL-11 protein was localised in mouse and human stomach. The impact of chronic, exogenous IL-11 on normal mouse stomach was examined histologically and transcriptionally by microarray, confirmed by mRNA and protein analysis. Functional impact of IL-11 on gastric acid secretion was determined.

Results: In mice infected with H.pylori, IL-11 was increased in fundic mucosa with temporal expression similar to IL-1b. IL-11 protein was localised predominantly to parietal cells in mouse and human stomach. Application of exogenous IL-11 to resulted in fundic parietal and chief cell loss, hyperplasia, mucous cell metaplasia and inflammation. Coincident with cellular changes were an increased gastric pH, altered parietal cell ultrastructure and altered gene expression, particularly genes involved in immune response and ion transport which could result in compromised acid secretion. We confirmed that a single dose of IL-11 effectively ablated the gastric response to histamine.

Conclusions: IL-11 is a parietal cell cytokine that blocks gastric acid secretion, likely via reducing expression of parietal cell ion transport genes, CCKb and histamine H2 receptors. IL-11 expression is increased in H. pylori infected mouse stomach and treatment of wild type mice with IL-11 induced changes in the gastric fundic mucosa reminiscent of chronic atrophic gastritis, a precursor to gastric cancer.

Figure 1

mRNA for IL-11 (Ai) and IL-1β (Aii) in stomachs of H pylori SS1-infected or control mice, killed at 3 or 12 months post-infection, standardized against rL32 and expressed as fold change compared to controls (ΔΔCt method). Immunolocalisation of IL-11 in fundic mucosa from wild-type (WT) mice (Bi-iii), human (iv) and H/K-ATPase β subunit deficient (H/Kβ^−/−) mice (v). To confirm antibody specificity, antibody was adsorbed with rhIL-11 (Bii) or peptide was substituted (Biii). Immunolocalisation of IL-11 (green) and the parietal cell lectin, DBA (red) in WT mouse (Bvi) and human (Bvii) tissue. Immunoblotting for IL-11 and GAPDH was performed on gastric fundic tissue from WT and H/Kβ^−/− mice and compared with rhIL-11 (19.05 kDa) (C), quantitative densitometry was performed of IL-11/GAPDH. Immunolocalisation of IL-11 (green) and pSTAT3 (red) (phosphorylated STAT3) in the fundus of WT (Di and ii) and IL-11 treated mice (Diii and iv). Bars refer to mean±SEM; *p≤0.05.

Figure 2

Wild-type (WT) mice treated with IL-11 or saline. pSTAT3 and STAT3 in fundus were measured by immunoblotting on duplicate blots. Quantitative densitometry was performed of pSTAT3/STAT3 (A). pSTAT3 (red) and H/K-ATPase (green) were immunolocalised in fundus from WT mice (B) treated with saline (i), IL-11 for 3 h (ii) or IL-11 every 6 h for 24 h (iii), 5 days (iv) or 7 days (v). The proportion of H/K-ATPase and pSTAT3-positive parietal cells was quantified (C). Bars refer to mean±SEM; *p≤0.05.

Figure 3

Parietal (A), zymogenic (B), proliferating (Ci-vi) and apoptotic (Cvii) cells were immunolocalised in saline control mice (i) and each of the IL-11 treatment groups (ii–v) using antibodies for H/KATPase, intrinsic factor, Ki-67 and activated caspase 3, respectively. Stained cells were expressed relative to control. Saline (Di) or IL-11-treated (Dii) sections were stained with Ki-67 and periodic acid Schiff reagent. Proliferating zone cells from fundus of saline (Ei) or IL-11-treated (Eii) mice were examined by electron microscopy. Arrows in 3Eii indicate the presence of electron dense granules. Bars refer to mean±SEM; *p≤0.05.

Figure 4

mRNA levels of antral gastrin (Ai) and fundic cholecystokinin B (CCKB) receptor (Aiii) and histamine H2 receptor (Aiv) were measured following IL-11 or saline treatment by quantitative PCR, standardised against rL32 and expressed as fold change compared with controls (ΔΔCt method). G cells (Aii) were localised in control mice and treatment groups. Stained cells/mm were quantified. Gastric content pH was measured from wild-type (WT) mice treated with IL-11 or saline (B). Electron microscopic analysis of parietal cells from saline (Ci–ii) or IL-11-treated mice (Ciii–iv). Gastric acid secretion (D) was measured at 15 min intervals in mice treated with (i) IL-11, (ii) histamine, (ii) histamine plus IL-11, 15 min later (iii) IL-11 plus histamine 15 min later. Acid secretion was expressed as percentage change from baseline. Bars refer to mean±SEM; *p≤0.05.

Figure 5

mRNA expression of potassium channels (KCN) (A), sodium-bicarbonate transporters (SLC26) (B) and miscellaneous transporters (C) were measured in the fundus of mice treated with IL-11 by quantitative PCR, standardised against rL32 and expressed as fold change compared with control mice (ΔΔCt method). Model of ion transport in the parietal cell (D). Bars refer to mean±SEM; *p≤0.05.

Figure 6

Polymorphonuclear cells were quantitated on stomach sections of mice treated with saline (Ai) or IL-11 (Aii) (B). IL-1β (Ci) and IL-33 (Cii) mRNA from gastric fundus of mice treated with IL-11 by quantitative PCR, standardised against the rL32 and expressed as fold change compared with controls (ΔΔCt method). IL-33 (Ciii) protein measured by immunoblotting and compared with GAPDH. mRNA levels of IL-4 (Di), IL-13 (Dii) and IFNγ (Diii) were measured as above. Bars refer to mean±SEM; *p≤0.05.